EX-96.2 26 exhibit962.htm EX-96.2
Technical Report Summary of the material Tailings Storage
Facilities
i
Technical
Report
Summary
of the
Material
Tailings
Storage
Facilities
Effective Date: 30 June 2022
Qualified Persons:
Mpfariseni Mudau Pr.Sci.Nat.
Steven Rupprecht FSAIMM
Prepared for:
Technical Report Summary of the material Tailings Storage
Facilities
ii
Date and Signature Page
This report entitled ‘Technical
Report Summary of the Material
Tailings Storage Facilities’, with
an effective
date
of
30
June
2022
was
prepared
for
Ergo
Mining
Proprietary
Limited
by
the
Qualified
Persons:
Mr Mpfariseni Mudau and Professor Steven Rupprecht
.
Dated at Johannesburg, 28 October 2022.
/s/ Mpfariseni Mudau
Mpfariseni Mudau (Pr.Sci.Nat.)
Resource Geology Manager
The RVN Group
/s/ Steven Rupprecht
Steven Rupprecht (FSAIMM)
Associate Principal Mining Engineer
The RVN Group
Technical Report Summary of the material Tailings Storage
Facilities
iii
1
EXECUTIVE SUMMARY
1
1.1
I
NTRODUCTION
1
1.2
P
ROPERTY
D
ESCRIPTION
1
1.3
M
INERAL
R
IGHTS AND
O
WNERSHIP
1
1.4
G
EOLOGY AND
M
INERALIZATION
2
1.5
E
VALUATION
D
RILLING AND
S
AMPLING
2
1.6
S
AMPLE
P
REPARATION
3
1.7
A
SSAYS
3
1.8
Q
UALITY
A
SSURANCE AND
Q
UALITY
C
ONTROL
4
1.9
M
ETALLURGICAL
S
AMPLING AND
T
ESTING
4
1.10
M
INERAL
R
ESOURCE
E
STIMATE
5
1.11
M
INERAL
R
ESERVE
E
STIMATE
6
1.12
P
ERMITTING
R
EQUIREMENTS
9
1.13
C
ONCLUSION AND
R
ECOMMENDATIONS
9
2
INTRODUCTION
11
2.1
P
ROJECT
B
ACKGROUND
11
2.2
T
ERMS OF
R
EFERENCE AND
P
URPOSE OF THE
T
ECHNICAL
R
EPORT
12
2.3
P
ARTICIPANTS AND
A
REAS OF
R
ESPONSIBILITIES
12
2.4
S
OURCES OF
I
NFORMATION
13
2.5
S
ITE
I
NSPECTION
13
2.6
U
NITS
,
C
URRENCIES AND
S
URVEY
C
OORDINATE
S
YSTEM
14
2.7
I
NDEPENDENCE
16
3
PROPERTY DESCRIPTION
17
3.1
L
OCATION AND
O
PERATIONS
O
VERVIEW
17
3.2
M
INERAL
R
IGHTS
C
ONDITIONS
21
3.3
M
INERAL
T
ITLE
21
3.4
V
IOLATION AND
F
INES
23
3.5
R
OYALTIES
23
3.6
L
EGAL
P
ROCEEDINGS AND
S
IGNIFICANT
E
NCUMBRANCES TO THE
P
ROPERTY
23
4
ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE
AND PHYSIOGRAPHY
24
4.1
T
OPOGRAPHY
,
E
LEVATION AND
V
EGETATION
24
4.2
A
CCESS
,
T
OWNS AND
R
EGIONAL
I
NFRASTRUCTURE
24
4.3
C
LIMATE
25
4.4
I
NFRASTRUCTURE AND
B
ULK
S
ERVICE
S
UPPLIES
25
4.5
P
ERSONNEL
S
OURCES
25
5
HISTORY
26
5.1
O
WNERSHIP
26
5.1.1
Crown Complex
26
5.1.2
City Deep complex
26
5.1.3
Knight Complex
26
Technical Report Summary of the material Tailings Storage
Facilities
iv
5.1.4
Ergo Complex
26
5.1.5
Marievale Complex
26
5.1.6
Grootvlei Complex
27
5.1.7
5A10/5L27
27
5.1.8
Daggafontein TSF
27
5.2
C
ONSTRUCTION OF THE
TSF
S AND
S
AND
D
UMPS
27
5.3
P
REVIOUS
E
XPLORATION AND
M
INE
D
EVELOPMENT
28
5.3.1
Previous Evaluation Drilling
28
5.3.2
Previous Development
28
6
GEOLOGICAL SETTING, MINERALIZATION AND DEPOSIT
30
6.1
R
EGIONAL
G
EOLOGY
30
6.2
M
INERALIZATION
,
L
OCAL AND
P
ROPERTY
G
EOLOGY
30
6.3
S
TRATIGRAPHY AND
C
ROSS
-
SECTIONS
31
6.4
D
EPOSIT
T
YPE
33
7
EXPLORATION
34
7.1
E
XPLORATION
34
7.2
T
OPOGRAPHIC
S
URVEYS
34
7.3
E
VALUATION
D
RILLING
34
7.4
D
RILLING
M
ETHODOLOGY
34
7.4.1
Auger Drilling
36
7.4.2
Reverse Circulation
36
7.5
C
ROWN
37
7.6
C
ITY
D
EEP
38
7.7
K
NIGHTS
39
7.7.1
4L14
39
7.7.2
4L50
40
7.8
E
RGO
41
7.8.1
7L15
41
7.8.2
Rooikraal
42
7.9
M
ARIEVALE
43
7.10
G
ROOTVLEI
C
OMPLEX
44
7.11
5A10/5L27
47
7.12
D
AGGAFONTEIN
TSF
48
7.13
L
OGGING AND
S
AMPLING
48
7.13.1
Logging
49
7.13.2
Sampling
49
7.14
S
AMPLE
R
ECOVERY
49
7.15
O
N
-
SITE
S
ECURITY
M
EASURES
49
7.16
C
OLLAR
S
URVEY
D
ATA
49
7.17
D
ENSITY
D
ETERMINATION
50
7.18
H
YDROLOGICAL
D
RILLING AND
T
EST
W
ORK
52
7.18.1
Crown Complex
52
7.18.2
City Deep Complex
53
7.18.3
Knights Complex
53
Technical Report Summary of the material Tailings Storage
Facilities
v
7.18.4
Ergo Complex
54
7.18.5
Marievale Complex
54
7.18.6
Grootvlei Complex
55
7.18.7
5A10/5L27
56
7.18.8
Daggafontein TSF
56
7.19
G
EOTECHNICAL
D
ATA
,
T
ESTING AND
A
NALYSIS
57
8
SAMPLE PREPARATION, ANALYSES AND SECURITY
58
8.1
S
AMPLING
G
OVERNANCE AND
Q
UALITY
A
SSURANCE
58
8.2
S
AMPLE
P
REPARATION AND
A
NALYSIS
58
8.2.1
On-site Sample Preparation
58
8.2.2
Laboratories, Sample Preparation and Analyses
59
8.2.3
QP Opinion
61
8.3
A
NALYTICAL
Q
UALITY
C
ONTROL
61
8.3.1
Nature and Extent of the Quality Control Procedures
61
8.3.2
Quality Control Results
62
8.3.3
QP Opinion
62
8.4
S
AMPLE
S
TORAGE AND
S
ECURITY
62
8.5
D
ATA
S
TORAGE AND
D
ATABASE
M
ANAGEMENT
62
9
DATA VERIFICATION
64
10
MINERAL PROCESSING AND METALLURGICAL TESTIN
G
65
10.1
N
ATURE AND
E
XTENT OF THE
M
ETALLURGICAL
T
ESTING
M
ETHOD
65
10.2
P
ROCEDURE
65
10.2.1
Slime Material
65
10.2.2
Sand Material
65
10.3
R
EPRESENTATIVE OF THE
S
AMPLES
66
10.4
D
ETAILS OF THE
L
ABORATORIES
66
10.5
R
ESULTS
66
10.6
I
NTERPRETATION OF THE
R
ESULTS
67
10.7
QP
O
PINION
68
11
MINERAL RESOURCE ESTIMATES
69
11.1
V
OLUME
M
ODELLING
70
11.2
B
ULK
D
RY
D
ENSITY
70
11.3
E
XPLORATORY
D
ATA
A
NALYSIS
70
11.4
E
STIMATION
T
ECHNIQUES
70
11.5
M
ODELLING AND
E
STIMATION
P
ARAMETERS
71
11.6
M
ODEL
V
ALIDATION
71
11.7
T
ECHNICAL AND
F
INANCIAL
P
ARAMETERS
72
11.8
U
NCERTAINTIES AND
C
LASSIFICATION
C
RITERIA
74
11.9
C
ROWN
C
OMPLEX
74
11.9.1
Exploratory Data Analysis
74
11.9.2
Modelling and Estimation Parameters
79
11.9.3
Technical and Economic Factors
80
11.9.4
Mineral Resource Classification Criteria
81
Technical Report Summary of the material Tailings Storage
Facilities
vi
11.9.5
Mineral Resource Statement
82
11.9.6
Mineral Resource Changes
82
11.9.7
Mineral Resource Risks and Uncertainty
82
11.10
C
ITY
D
EEP
C
OMPLEX
83
11.10.1
Exploratory Data Analysis
83
11.10.2
Modelling and Estimation Parameters
86
11.10.3
Technical and Economic Factors
87
11.10.4
Mineral Resource Classification Criteria
87
11.10.5
Mineral Resource Statement
87
11.10.6
Mineral Resource Changes
88
11.10.7
Mineral Resource Risks and Uncertainty
88
11.11
K
NIGHTS
C
OMPLEX
89
11.11.1
Exploratory Data Analysis
89
11.11.2
Modelling and Estimation Parameters
96
11.11.3
Technical and Economic Factors
98
11.11.4
Mineral Resource Classification Criteria
98
11.11.5
Mineral Resource Statement
99
11.11.6
Mineral Resource Changes
100
11.11.7
Mineral Resource Risks and Uncertainty
100
11.12
E
RGO
C
OMPLEX
100
11.12.1
Exploratory Data Analysis
100
11.12.2
Modelling and Estimation Parameters
108
11.12.3
Technical and Economic Factors
108
11.12.4
Mineral Resource Classification Criteria
109
11.12.5
Mineral Resource Statement
110
11.12.6
Mineral Resource Changes
110
11.12.7
Mineral Resource Risks and Uncertainty
111
11.13
M
ARIEVALE
C
OMPLEX
111
11.13.1
Exploratory Data Analysis
111
11.13.2
Modelling and Estimation Parameters
116
11.13.3
Technical and Economic Factors
116
11.13.4
Mineral Resource Classification Criteria
116
11.13.5
Mineral Resource Statement
117
11.13.6
Mineral Resource Changes
118
11.13.7
Mineral Resource Risks and Uncertainty
118
11.14
G
ROOTVLEI
C
OMPLEX
119
11.14.1
Exploratory Data Analysis
119
11.14.2
Modelling and Estimation Parameters
123
11.14.3
Technical and Economic Factors
123
11.14.4
Mineral Resource Classification Criteria
124
11.14.5
Mineral Resource Statement
125
11.14.6
Mineral Resource Changes
126
11.14.7
Mineral Resource Risks and Uncertainty
126
11.15
5A10/5L27
S
AND
D
UMPS
126
11.15.1
Exploratory Data Analysis
126
Technical Report Summary of the material Tailings Storage
Facilities
vii
11.15.2
Modelling and Estimation Parameters
128
11.15.3
Technical and Economic Factors
128
11.15.4
Mineral Resource Classification Criteria
128
11.15.5
Mineral Resource Statement
130
11.15.6
Mineral Resource Changes
130
11.15.7
Mineral Resource Risks and Uncertainty
131
11.16
D
AGGAFONTEIN
TSF
131
11.16.1
Exploratory Data Analysis
131
11.16.2
Modelling and Estimation Parameters
132
11.16.3
Technical and Economic Factors
133
11.16.4
Mineral Resource Classification Criteria
133
11.16.5
Mineral Resource Statement
134
11.16.6
Mineral Resource Changes
135
11.16.7
Mineral Resource Risks and Uncertainty
135
11.17
S
UMMARY
M
INERAL
R
ESOURCE
E
STIMATES
136
11.18
QP’
S
O
PINION
139
12
MINERAL RESERVE ESTIMATES
140
12.1
G
RADE
C
ONTROL AND
R
ECONCILIATION
140
12.2
C
UT
-
OFF
G
RADE
E
STIMATION
141
12.3
E
STIMATION AND
M
ODELLING
T
ECHNIQUES
142
12.4
M
INERAL
R
ESERVE
C
LASSIFICATION
C
RITERIA
142
12.5
M
INERAL
R
ESERVES
S
TATEMENT
142
12.6
QP
S
TATEMENT ON THE
M
INERAL
R
ESERVE
E
STIMATION
144
13
MINING METHODS
145
13.1
M
INING
M
ETHOD
145
13.1.1
Hydraulic Mining
146
13.1.2
Conventional Load, Haul and Slurry
149
13.2
M
INING
S
ECTIONS
152
13.2.1
West Rand
155
13.2.2
Central Rand Section – City Section
155
13.2.3
East Rand Section
156
13.3
M
INE
D
ESIGN AND
S
CHEDULE
157
13.4
G
EOTECHNICAL AND
G
EOHYDROLOGY
160
13.5
R
EQUIREMENTS FOR
S
TRIPPING
161
13.6
M
INING
E
QUIPMENT AND
P
ERSONNEL
R
EQUIREMENTS
162
13.7
M
INE
P
LANS
162
13.7.1
Introduction
162
13.7.2
Central Rand
162
13.7.3
East Rand (Ergo)
162
14
PROCESSING AND RECOVERY METHODS
165
14.1
I
NTRODUCTION
165
14.2
P
LANT
F
EED
G
RADE AND
M
ETALLURGICAL
T
EST
W
ORK
165
14.3
M
INERAL
P
ROCESS AND
E
QUIPMENT
C
HARACTERISTICS
168
Technical Report Summary of the material Tailings Storage
Facilities
viii
14.3.1
Reception
168
14.3.2
De-sanding Section
168
14.3.3
Carbon-in-Leach
168
14.3.4
Carbon Treatment
168
14.3.5
Plant Services
169
14.4
P
ERSONNEL
R
EQUIREMENTS
169
14.5
E
NERGY AND
W
ATER
R
EQUIREMENTS
169
14.6
P
ROCESS
M
ATERIALS
R
EQUIREMENTS
169
15
INFRASTRUCTURE
170
15.1
R
OADS
170
15.2
S
ITE
O
FFICES AND
W
ORKSHOPS
170
15.3
P
OWER
170
15.4
P
UMPS AND
P
IPELINES
171
15.5
W
ATER
172
15.6
I
NFRASTRUCTURE
172
15.7
T
AILINGS
D
ISPOSAL
174
15.8
C
ONCLUSION
176
16
MARKET STUDIES
177
16.1
M
ARKETS
177
16.2
G
OLD
P
RICE
177
16.3
E
XCHANGE
R
ATE
T
RENDS
178
16.4
G
LOBAL
D
EMAND
179
16.5
G
LOBAL
S
UPPLY
180
16.6
C
ONCLUDING
C
OMMENTS
181
17
ENVIRONMENTAL STUDIES
182
17.1
R
ESULTS OF
E
NVIRONMENTAL
S
TUDIES
182
17.2
R
EQUIREMENTS FOR
T
AILINGS
D
ISPOSAL
,
S
ITE
M
ONITORING AND
W
ATER
M
ANAGEMENT
182
17.2.1
Site Monitoring
183
17.2.2
Water Management
183
17.2.3
Vegetation Monitoring
183
17.2.4
Vegetation Maintenance
183
17.2.5
Water Monitoring
183
17.2.6
Legal and Permitting
184
17.3
P
LAN
N
EGOTIATIONS
,
OR
A
GREEMENTS WITH
L
OCAL
I
NDIVIDUALS OR
G
ROUPS
184
17.4
M
INE
C
LOSURE
P
LANS
R
EMEDIATION
P
LANS
,
AND
A
SSOCIATED
C
OSTS
185
17.5
QP
S
TATEMENT ON THE
E
NVIRONMENTAL
S
TUDIES
,
P
ERMITTING
,
P
LANS
,
N
EGOTIATIONS
,
WITH
L
OCAL
I
NDIVIDUALS OR
G
ROUPS
186
18
CAPITAL AND OPERATION COSTS
187
18.1
C
APITAL
E
XPENDITURE
187
18.1.1
Ergo Section Capital Expenditure
187
18.1.2
City Capital Expenditure
190
18.1.3
Knights Capital Expenditure
190
Technical Report Summary of the material Tailings Storage
Facilities
ix
18.1.4
QP commentary
190
18.2
O
PERATING
C
OSTS
191
19
ECONOMIC ANALYSIS
192
19.1
E
CONOMIC
A
NALYSIS
192
19.2
S
ENSITIVITY
A
NALYSIS
195
19.3
R
ISK
A
SSESSMENT
195
19.3.1
Rising Electricity Prices and Eskom Supply Distribution
195
19.3.2
Tailings Storage Facility Capacity
196
19.3.3
Social Unrest
196
19.3.4
Increased Crime
196
19.3.5
Depletion of Ergo’s Mineral Reserves
197
19.3.6
Social Licenses to Operate
197
19.3.7
Fluctuations in the Gold Price and Exchange Rate
197
19.3.8
Supply and Cost of Water
198
20
ADJACENT PROPERTIES
199
21
OTHER RELEVANT DATA AND INFORMATION
199
22
INTERPRETATION AND CONCLUSIONS
200
23
RECOMMENDATIONS
200
24
REFERENCES
201
25
RELIANCE ON INFORMATION PROVIDED BY REGISTRANT
201
26
QUALIFIED PERSONS DISCLOSURE CONSENT
202
Technical Report Summary of the material Tailings Storage
Facilities
x
Figure 3.1:
Location of the
Material TSFs
and Infrastructure (the
material properties of
Ergo)
................................
................................
................................
............................ 19
Figure 3.2:
Location of the
Material Properties
in Relation to
the Smaller TSFs
and Clean-
up Operations
................................
................................
................................
............
20
Figure 6.1:
A Typical Stratigraphy for Ergo’s TSFs ................................
................................
..
32
Figure 6.2:
Grootvlei Complex (6L17) Map showing Location of
Cross-section
...................... 32
Figure 6.3:
Cross-section of the Grootvlei Complex (6L17)
................................
....................... 33
Figure 7.1:
Crown Complex: Map showing drill hole Locations
................................
..........
37
Figure 7.2:
City Deep Complex: Map showing Drill Hole Locations
................................
........
38
Figure 7.3:
Knights Complex - 4L14: Map showing Drill Hole Locations
................................
....
39
Figure 7.4:
Knights Complex - 4L50: Map showing Drill Hole Locations
................................
....
40
Figure 7.5:
Ergo Complex - 7L15: Map showing Drill Hole Locations
................................
........
41
Figure 7.6:
Ergo Complex - Rooikraal: Map showing Drill Hole Locations
................................ 42
Figure 7.7:
Marievale Complex: Map showing Drill Hole Locations
................................
.........
43
Figure 7.8:
Grootvlei Complex - 6L16: Map showing Drill Hole Locations
................................ 44
Figure 7.9:
Grootvlei Complex
- 6L17: Map showing Drill Hole Locations
................................ 45
Figure 7.10: Grootvlei Complex - 6L17A: Map showing Drill
Hole Locations
........................... 46
Figure 7.11:
5A10/5L27: Map showing Drill Hole Locations
................................
................. 47
Figure 7.12:
Daggafontein
Complex
-
Daggafontein
TSF:
Map
showing
Drill
Hole
Locations ................................................................
................................
.................... 48
Figure 8.1:
Cone and Quartering Method
................................
................................
................. 58
Figure 11.1:
3L7 (Mooifontein): Distribution of Raw Gold Capped Data
.......................... 75
Figure 11.2:
3L7 (Mooifontein): Distribution of Composited Gold Data
............................ 76
Figure 11.3:
3L8 (GMTS): Distribution of Raw Gold Capped Data
................................
.....
76
Figure 11.4:
3L8 (GMTS): Distribution of Composited Gold Data
................................
.......
77
Figure 11.5:
3L5 (Diepkloof: Diepkloof): Distribution of Raw Gold Capped
Data ............
77
Figure 11.6:
3L5 (Diepkloof: Diepkloof): Distribution of Composited Gold
Data
...............
78
Figure 11.7:
3L5 (Diepkloof: Homestead): Distribution of Raw Gold Capped
Data
.........
78
Figure 11.8:
3L5 (Diepkloof: Homestead): Distribution of Composited Gold
Data
...........
79
Figure 11.9:
4L3: Distribution of Raw Gold Capped Data ................................
.................. 83
Figure 11.10:
4L3: Distribution of Composited Gold Data................................
..................... 84
Figure 11.11:
4L4: Distribution of Raw Gold Capped Data ................................
.................. 84
Figure 11.12:
4L4: Distribution of Composited Gold Data................................
..................... 85
Figure 11.13:
4L6:
Distribution of Raw Gold Capped Data
................................
......................... 85
Technical Report Summary of the material Tailings Storage
Facilities
xi
Figure 11.14:
4L6: Distribution of Composited Gold Data................................
..................... 86
Figure 11.15:
4L14: Distribution of Slime Raw Data
................................
................................ 89
Figure 11.16:
4L14: Log Distribution of Slime Raw Data
................................
......................... 90
Figure 11.17:
4L14: Distribution of Slime 6m Composited Data
................................
............
90
Figure 11.18:
4L14: Log Distribution of Slime 6m Composited Data
................................
.....
91
Figure 11.19:
4L14: Distribution of Soil Raw Data
................................
................................
...
91
Figure 11.20:
4L14: Log Distribution of Soil Raw Data
................................
............................ 92
Figure 11.21:
4L14: Distribution of Soil Raw Capped Data................................
.................... 92
Figure 11.22:
4L14: Log Distribution of Soil Raw Capped Data
................................
............
93
Figure 11.23:
4L50: Log Distribution of Raw Slime Data
................................
......................... 93
Figure 11.24:
4L50: Distribution of Raw Slime Raw Data
................................
........................ 94
Figure 11.25:
4L50: Log Distribution of Raw Capped Slime Data
................................
.........
94
Figure 11.26:
4L50: Distribution of Raw Capped Slime Data
................................
................ 95
Figure 11.27:
4L50: Distribution of 3m Composited Slime Data
................................
............
95
Figure 11.28:
4L50: Log Distribution of 3m Composited Slime Data
................................
.....
96
Figure 11.29:
4L50: Head Grade versus Modelled Average Gold Grade
........................... 99
Figure 11.30:
Rooikraal: Distribution of Raw Gold Data
................................
...................... 101
Figure 11.31:
Rooikraal: Log Distribution of Composited Gold Data
................................
.
102
Figure 11.32:
7L15: Plan showing North and South Domains
................................
.............. 103
Figure 11.33:
7L15: Distribution of 2015 Raw Data - North Domain
................................
....
104
Figure 11.34:
7L15: Log Distribution of 2016 Raw Data - North Domain
............................. 104
Figure 11.35:
7L15: Distribution of 2015 Raw Data - South Domain
................................
....
105
Figure 11.36:
7L15: Log Distribution of 2016 Raw Data - South Domain............................. 105
Figure 11.37:
7L15: Distribution of 3m Composited Slime Data - South Domain
............... 106
Figure 11.38:
7L15: Log Distribution of 3m Composited Slime Data - South
Domain
........
106
Figure 11.39:
7L15: Distribution of 3m Composited Slime Data - North Domain
............... 107
Figure 11.40:
7L15: Log Distribution of 3m Composited Slime Data - North
Domain
........
107
Figure 11.41:
7L4: Distribution of Capped Raw Gold Data ................................
............... 112
Figure 11.42:
Distribution of Composited Raw Gold Data
................................
................. 112
Figure 11.43:
7L5: Distribution of Raw Gold Data
................................
................................ 113
Figure 11.44:
7L5: Distribution of Composited Gold Data................................
................... 113
Figure 11.45:
7L6: Distribution of Raw Gold Data
................................
................................ 114
Figure 11.46: 7L6: Distribution of Composited Gold Data
................................
...................... 114
Technical Report Summary of the material Tailings Storage
Facilities
xii
Figure 11.47:
7L7: Distribution of Raw Capped Gold Data ................................
................ 115
Figure 11.48:
7L7: Distribution of Composited Capped Gold Data
................................
...
115
Figure 11.49:
6L16: Distribution of Raw Capped Gold Data ................................
.............. 120
Figure 11.50:
6L16: Distribution of Composited Gold Data
................................
................. 120
Figure 11.51:
6L17: Distribution of Raw Capped Gold Data ................................
.............. 121
Figure 11.52:
6L17: Distribution of Composited Gold Data
................................
................. 121
Figure 11.53:
6L17A: Distribution of Raw Capped Gold Data
................................
...........
122
Figure 11.54:
6L17A: Distribution of Composited Gold Data
................................
............. 122
Figure 11.55:
5A10/5l27: Distribution of Raw Gold Data
................................
..................... 127
Figure 11.56:
5A10/5l27: Distribution of Composited Gold Data ................................
.......
127
Figure 11.57:
Boxplots for the Different Drilling Campaigns
................................
................ 131
Figure 11.58:
Log Probability Plot
................................
................................
.......................... 132
Figure 11.59:
Mineral Resource Classification................................
................................
......
134
Figure 11.60:
Mineral Resource Reconciliation (Inclusive) ................................
................. 139
Figure 13.1:
Typical Tailing Storage Facility
................................
................................
........
146
Figure 13.2:
Example of Hydraulic Mining
................................
................................
..........
147
Figure 13.3:
Hydraulic Mining Process Diagram
................................
................................ 148
Figure 13.4:
Typical Mining Method for a TSF
................................
................................
.....
149
Figure 13.5:
Example of Loading with a FEL
................................
................................
.......
150
Figure 13.6:
Example of Loading with a FEL into a Hopper
................................
.............. 150
Figure 13.7:
Example of Material on Conveyor
................................
................................
.
151
Figure 13.8:
Slurry Point for Loading
................................
................................
.................... 151
Figure 13.9:
Ergo Sections
................................
................................
................................
....
153
Figure 13.10:
Ergo Operations Overview ................................
................................
............. 154
Figure 13.11:
Hydraulic Mining with Monitor showing Distance and Angle
...................... 161
Figure 13.12:
Daggafontein TSF Top Cut Mining Sequence
................................
............... 163
Figure 13.13:
Daggafontein TSF Middle Cut Mining Sequence
................................
.........
163
Figure 13.14:
Daggafontein TSF Bottom Cut Mining Sequence
................................
.........
164
Figure 14.1:
Process Flow Diagram
................................
................................
..................... 167
Figure 15.1:
Above Ground Pipeline System ................................
................................
.....
171
Figure 15.2:
Rooikraal General Arrangement - Site Layout
................................
.............. 173
Figure 15.3:
Brakpan/Withok TSF
................................
................................
......................... 175
Figure 15.4:
Placement of Tailings Material at Brakpan/Withok TSF
................................ 175
Technical Report Summary of the material Tailings Storage
Facilities
xiii
Figure 19.1:
Ergo LoM Production Tonnage
................................
................................
.......
192
Figure 19.2:
Ergo LoM Gold Production
................................
................................
............. 193
Figure 19.3:
Sensitivity Analysis
................................
................................
............................ 195
Figure 19.4:
30-Year Gold Price in USD/oz (1992 to 2022)
................................
................ 198
Graph 1: Gold Price Historical Trendline
................................
................................
.................. 178
Graph 2: Exchange Rate Historical Trendline
................................
................................
.........
178
Graph 3: Global Gold Demand from 2012 to 2021
................................
................................ 179
Graph 4: Global Gold Supply from 2012 to 2021
................................
................................
....
180
Table 1.1: Ergo’s Mineral Resource Statement as at 30 June 2022 (Inclusive)
......................... 5
Table 1.2: Ergo’s Mineral Resource Statement as at 30 June 2022 (Exclusive)
........................ 6
Table 1.3: Ergo’s Mineral Reserve Statement as at 30 June 2022 ................................
.............
6
Table 1.4: Mineral Reserve Reconciliation ................................
................................
.................. 7
Table 2.1: List of QPs and their Responsibilities
................................
................................
..........
13
Table 2.2: List of Abbreviations
................................
................................
................................
...
14
Table 3.1: Footprint Areas of the Material TSFs................................
................................
..........
18
Table 3.2: Mineral Rights Information as at 30 June 2022 ................................
........................ 22
Table 3.3: Land Tenure Information
................................
................................
........................... 22
Table 5.1: History and Status of the TSFs and Sand Dump
................................
....................... 28
Table 5.2: ERGO Production History
................................
................................
........................... 29
Table 6.1:
Origin of the TSF and Sand Dump Material ................................
............................. 31
Table 7.1:
Survey Details of the Material from the TSFs and Sand Dumps
.............................. 35
Table 7.2:
Bulk Density Information and Statistics
................................
................................
.....
51
Table 7.3:
GMTS (3L8) Moisture Content ................................
................................
................... 52
Table 7.4:
Diepkloof (3L5) Moisture Content
................................
................................
.............
52
Table 7.5:
Mooifontein (3L7) Moisture Content
................................
................................
.........
52
Table 7.6:
4L3 Moisture Content
................................
................................
................................
.
53
Table 7.7:
4L4 Moisture Content
................................
................................
................................
.
53
Table 7.8:
4L6 Moisture Content
................................
................................
................................
.
53
Table 7.9:
4L14 Moisture Content
................................
................................
............................... 53
Technical Report Summary of the material Tailings Storage
Facilities
xiv
Table 7.10:
4L50 Moisture Content
................................
................................
...................... 54
Table 7.11:
Rooikraal Moisture Content
................................
................................
..............
54
Table 7.12:
7L15 Moisture Content
................................
................................
...................... 54
Table 7.13:
7L4: Moisture Content
................................
................................
....................... 54
Table 7.14:
7L5: Moisture Content
................................
................................
....................... 55
Table 7.15:
7L6: Moisture Content
................................
................................
....................... 55
Table 7.16:
7L7: Moisture Content
................................
................................
....................... 55
Table 7.17:
6L16 Moisture Content
................................
................................
...................... 55
Table 7.18:
6L17 Moisture Content
................................
................................
...................... 56
Table 7.19:
6L17A Moisture Content
................................
................................
.................... 56
Table 7.20:
5A10/5L27 Moisture Content
................................
................................
............
56
Table 7.21:
Daggafontein Moisture Content
................................
................................
......
56
Table 8.1:
Laboratories Used
................................
................................
................................
......
60
Table 10.1:
Summary of Predicted Ergo Processing Plant Performance
.......................... 67
Table 11.1:
Financial and Technical Data considered for Mineral Resource
.................. 72
Table 11.2:
Mineral Resource Estimate Cut-off Grades
................................
..................... 73
Table 11.3:
Search Parameters: Inverse Distance Estimation Method
................................ 79
Table 11.4:
Confidence Levels for Key Criteria for Mineral Resource Classification
.......
81
Table 11.5:
Crown Complex Mineral Resource Estimate (Exclusive)
................................
...
82
Table 11.6:
Search Parameters: Inverse Distance Estimation Method
................................ 86
Table 11.7:
Confidence
Levels
of
Key
Criteria
for
Classification
of
the
TSFs
Mineral
Resources ................................
................................
................................
................... 87
Table 11.8:
City Deep Complex Mineral Resource Estimates (Inclusive).............................
88
Table 11.9:
City Deep Complex Mineral Resource Estimates (Exclusive)
............................ 88
Table 11.10:
4L14: Search Parameters: Nearest Neighbor Estimation Method
................. 96
Table 11.11:
4L14: Search Parameters: Inverse Distance Estimation
Method
.................... 96
Table 11.12:
4L50: Search Parameters: Nearest Neighbor Estimation Method
................. 97
Table 11.13:
4L50: Search Parameters: Inverse Distance Estimation
Method
.................... 97
Table 11.14:
Confidence Levels of Key
Criteria for Classification
of the 4L14and 4L50
TSFs Mineral Resources ................................
................................
.............................. 98
Table 11.15:
Knights Complex Mineral Resource Estimates (Inclusive)
............................... 99
Table 11.16:
Knights Complex Mineral Resource Estimates (Exclusive)
............................ 100
Table 11.17:
Rooikraal: Search Parameters: Inverse Distance Estimation
Method .........
108
Table 11.18:
7L15: Search Parameters: Inverse Distance Estimation
Method
.................. 108
Technical Report Summary of the material Tailings Storage
Facilities
xv
Table 11.19:
Ergo:
Confidence
Levels
for
Key
Criteria
for
Mineral
Resource
Classification ................................
................................
................................
............ 109
Table 11.20:
Ergo Mineral Resource Estimates (Inclusive)................................
.................. 110
Table 11.21:
Ergo Mineral Resource Estimates (Exclusive)
................................
................. 110
Table 11.22:
Search Parameters
................................
................................
.......................... 116
Table 11.23:
Confidence Levels for Key Criteria for Mineral Resource Classification
.....
116
Table 11.24:
Marievale Mineral Resource Estimates (Inclusive)
................................
........
117
Table 11.25:
Marievale Resource Estimates (Exclusive)
................................
..................... 118
Table 11.26:
Search Parameters: Inverse Distance Estimation Method
........................... 123
Table 11.27:
Confidence Levels for Key Criteria for Mineral Resource Classification
.....
125
Table 11.28:
Grootvlei Complex Mineral Resource Estimates (Exclusive)
........................ 126
Table
11.29:
Search Parameters: Inverse Distance Estimation Method
................................
.......
128
Table 11.30:
Confidence Levels for Key Criteria for Mineral Resource Classification
.....
129
Table 11.31:
5A10/5L27 Mineral Resource Estimates (Inclusive)
................................
........
130
Table 11.32:
5A10/5L27 Mineral Resource Estimates (Exclusive)
................................
.......
130
Table 11.33:
Search Parameters
................................
................................
.......................... 133
Table
11.34:
Confidence Levels for Key Criteria for Mineral Resource Classification
................... 133
Table 11.35:
Daggafontein TSF Mineral Resource Estimate (Inclusive)
............................ 134
Table 11.36:
Daggafontein TSF Mineral Resource Estimate (Exclusive)
............................ 135
Table 11.37:
Inclusive Mineral Resources of
the 19 Material Properties
as at 30
June
2022
136
Table 11.38:
Exclusive Mineral Resources of the 19 Material Properties as
at 30 June
2022
137
Table 11.39:
Ergo Inclusive Mineral Resources Statement as at 30 June 2022
................ 138
Table
11.40:
Ergo Exclusive Mineral Resources Statement as at 30 June 2022
............................ 138
Table 12.1:
Reconciliation of RoM Head Grade (Au)
................................
......................... 140
Table 12.2:
Reconciliation of RoM Tonnage
................................
................................
.....
140
Table 12.3:
Cut-off Grade and Mineral Reserve Grades
................................
................. 141
Table 12.4:
Ergo TSF Mineral Reserves Statement as at 30 June 2022
............................ 143
Table 12.5:
Mineral Reserve Reconciliation
................................
................................
......
143
Table 13.1:
Historical Ergo Operational Results
................................
................................
.
145
Table 13.2:
Central Rand (City Section)
................................
................................
............ 155
Table 13.3:
Central Rand (Knights Section)
................................
................................
......
156
Table 13.4:
East Rand Section (Ergo Section)
................................
................................
...
157
Technical Report Summary of the material Tailings Storage
Facilities
xvi
Table 13.5:
Summary of Modifying Factors for LoM Plan
................................
................. 158
Table 13.6:
Ergo Forecast Production from July 2021 to June 2034
................................ 159
Table 14.1:
Ergo Process Recoveries ................................
................................
.................... 168
Table 16.1:
Above Ground Gold Stocks in 2021
................................
............................... 177
Table 16.2:
Long Term Consensus Forecasts in Nominal Terms
................................
.......
179
Table 16.3:
Global Gold Production ................................
................................
................. 180
Table 17.1:
Ergo Water Consumption ................................
................................
............... 183
Table 17.2:
SLP Financial Provision Summary
................................
................................
....
185
Table 17.3:
Ergo Rehabilitation Financial Provision Summary
................................
.........
186
Table 18.1:
Capital Expenditure Summary ................................
................................
.......
187
Table 18.2:
Rooikraal Capital Expenditure Estimate
................................
........................ 187
Table 18.3:
Marievale Capital Pump Stations ................................
................................
..
188
Table 18.4:
Marievale Total Capital Expenditure Summary
................................
............ 188
Table 18.5:
Daggafontein Capital Pump Stations ................................
........................... 188
Table 18.6:
Daggafontein Capital Expenditure Summary
................................
.............. 189
Table 18.7:
Non-material TSF Capital Expenditure for the Ergo Section
......................... 189
Table 18.8:
Withok Compartment Capital Expenditure
................................
.................. 189
Table 18.9:
Solar Power Project Capital Estimate ................................
............................ 190
Table 18.10:
City Total Capital Expenditure Summary
................................
....................... 190
Table 18.11:
Average LoM Operating Cost for Ergo
................................
.......................... 191
Table 19.1:
Economic Analysis
................................
................................
........................... 194
Table 26.1:
Qualified Person’s Details................................
................................
................ 202
Technical Report Summary of the material Tailings Storage
Facilities
1
1
Executive Summary
1.1
Introduction
Ergo Mining (Proprietary)
Limited (Ergo) is a
wholly owned subsidiary
of DRDGOLD Limited
(DRDGOLD).
DRDGOLD is domiciled in South
Africa and listed on the
Johannesburg Stock Exchange
(JSE: DRD) and
New York Stock Exchange (NYSE: DRD). DRDGOLD, a South African-based gold mining company, has a
100% share in Ergo. DRDGOLD is a Tailings Storage Facilities
(TSFs) retreatment company.
The TSFs
Mineral
Resource
and
Mineral
Reserve
estimates
declared
in
this
Technical
Report
Summary
(this Report) are 100%
attributable to DRDGOLD.
The TSFs covered are
from Crown, City
Deep, Knights,
Ergo, Marievale and Grootvlei Complexes,
5A10/5L27 sand dump and Daggafontein TSF.
The Mineral Resource
and Mineral
Reserve estimate contained
in this Technical
Report Summary were
compiled
and
reported
by
the
Qualified
Persons
(QPs)
for
DRDGOLD
in
accordance
with
Items
601(b)(96) and 1300 through 1305 of
Regulation S-K (Title 17, Part 229,
Items 601(b)(96) and 1300 through
1305
of
the
Code
of
Federal
Regulations)
promulgated
by
the
Securities
and
Exchange
Commission
(SEC).
This document is
the first submission
of a Technical
Report Summary under
Regulation S-K; thus,
it is not
an update of a previously filed Technical Report Summary.
This
Technical
Report
Summary
is
based
on
information
available
until
30
June
2022.
There
were
no
material changes between the effective and reporting
dates.
1.2
Property Description
Ergo is reclaiming
TSFs and sand
dumps in the
City of Johannesburg
and the City
of Ekurhuleni, Gauteng,
South Africa. The Crown and City Deep Complexes
are in the City of Johannesburg,
while all other TSFs
are located in the City of Ekurhuleni. A total of 19
material properties are discussed in this report.
1.3
Mineral Rights and Ownership
Ergo’s title in
its Mineral Resources
is vested in
common law ownership
and/or contractual arrangements
and
Prospecting
Rights,
and
its
competency
to
mine
the
same
lie
in
various
Mining
Rights
that
were
converted (and
consolidated)
in terms
of the
provisions
of the
MPRDA and
Environmental
Approvals.
Ergo has submitted an
application to renew and
consolidate all their Mining
Rights into a single
Mining
Right;
this
application
is
receiving
attention
from
the
Department
of
Mineral
Resources
and
Energy
(DMRE).
Renewal
applications
have
been
submitted
to
the
DMRE
for
each
expired
Right.
Ergo
has
applied to extend the consolidated Mining Right for 30 years,
which is the maximum allowable renewal
period as detailed in the Mineral and Petroleum Resources Development Act,
2002 (Act No. 28 of 2002)
(MPRDA).
This report has considered section 24(5) of the MPRDA, as
amended:
“
A mining right in respect of which
an application for renewal has
been lodged shall despite its expiry
date remain in force until such time as such application has
been granted or refused.
”
The same applies to the Prospecting Rights through section
18(5) of the MPRDA.
Technical Report Summary of the material Tailings Storage
Facilities
2
1.4
Geology and Mineralization
The
TSFs
are
man-made
features.
The
material
in
the
TSFs
has
been
processed
through
metallurgical
plants
that
generate
residue
(tailings),
which
are
relatively
uniform
in
comparison
with
the
natural
deposit from which the material is derived. The variation between grades is small as the process residue
TSFs were constructed
in layers.
Grade variation
primarily follows
variations in
the processing
and, to
a
lesser extent, the primary deposits characteristic.
The
TSFs
are
the
waste
product
of
the
mineral
recovery
process.
They
took
the
form
of
a
liquid
slurry
made of
fine mineral
particles -
created when
mined ore
was crushed,
milled and
processed. The
tailings
were
pumped
to
TSFs
which
were
constructed
using
the
Upstream
Deposition
Methodology.
Water
contained within
the slurry was
removed via various
drainage systems and
then re-used in
the process
whilst
the
TSF
was
in
operation.
Once
a
TSF
is
decommissioned
and
declared
dormant,
water
is
still
drained
and
recovered
but
evaporation
and
seepage
are
the
main
reasons
for
water
loss.
Rehabilitation
of the
side
slopes and
top surface
of the
TSF, by
way of
vegetation
and irrigation
,
was
previously only implemented once the TSF was declare
d
dormant.
1.5
Evaluation Drilling and Sampling
A qualified
surveyor
surveyed
all evaluation
drill
hole positions
.
Holes were
drilled
into the
TSF at
1.5m
intervals
to
determine
grade
distribution.
The
number
of
samples
(at
1,5m
intervals),
correlated
with
surveying data, provided the height of the TSF and
tonnage based on a bulk solid’s density of 1.42.
The
typical
exploration
programs
(geophysics,
trenching,
mapping,
and
soil
sampling)
were
not
undertaken
on
the
TSFs.
Evaluation
drilling
programs
were
conducted
on
the
TSFs.
No
exploration
is
required to locate TSFs, as their locations are known
and established above the natural ground level.
Two
drilling
techniques
were
followed
by
specialized
drilling
contractors
on
the
TSFs.
The
Reverse
Circulation (RC) method was
used where auger drilling techniques
could not drill to
the base of
the TSFs,
mainly due to the drill hole length and moisture of
the TSFs towards their bases.
With auger drilling, the rotation of a helical screw causes the
blade of the screw to lift the sample to the
surface. This drilling
method does not
require heavy
machinery to drill
to the desired
depth. The auger
method
can
be
used
for
shallow
environmental
drilling,
geotechnical
drilling,
soil
engineering
and
mineral deposits where the formation is soft and the hole does not collapse. This is done by pressing the
spiral rods into the ground using a drilling head
machine which can drill up to a depth of 50m.
Samples were collected through the spiral at 1.5m intervals, and the spiral was cleaned with water and
brushed after every run.
The RC
drilling
technique
was chosen
in preference
to auger
drilling
in certain
locations because
RC
drilling
could
drill
deeper
than
auger
drilling.
In
addition,
because
of
its
higher
power,
RC
can
drill
through wet material and has
better recovery percentages than auger drilling,
which loses wet samples
through its spiral.
The RVN Group (Proprietary)
Limited (The RVN Group) monitored the
drilling and sampling process. The
methods
were
to
an
acceptable
industry
standard,
and
the
results
were
considered
appropriate
for
further evaluation.
Technical Report Summary of the material Tailings Storage
Facilities
3
Logging was carried out as per the
Ergo protocols and the QP considered it appropriate for the deposit
under
consideration.
Drill
holes
were
logged
on-site
by
the
RVN
Geologist.
Samples
of
1.5m
length
intervals were taken for the
entire length of the drill
holes. Samples were classified according to
whether
they were slimes or
soil, moist or wet
and on color. All
drill hole data was
provided to Ergo in
electronic
and hardcopy formats as drill hole logs, sample logs and assay
certificates.
1.6
Sample Preparation
As the samples were moist to wet, all samples were split on-site using
the cone and quartering method.
One set was
prepared for routine exploration analysis
for use in the
Mineral Resource estimation and the
other set for metallurgical process test work. All the
samples were presented to the laboratory in a well-
organized
and
sorted
manner
with
easily
understandable
documentation,
including
fully
completed
Sample Submission Forms.
The samples were sent to the following three laboratories for
further preparation and assaying:
●
MAED
Metallurgical
Laboratories
(Proprietary)
Limited
(MAED)
is
located
at
Ergo’s
processing
plant in Brakpan. The facility is not accredited,
however is used by Ergo for its grade control and
daily sampling.
Although MAED is
not owned
by Ergo,
it is
situated in the
Ergo processing
plant
and was supplied with all routine exploration samples.
●
SGS
South
Africa
(Proprietary)
Limited
(SGS)
is
located
in
Randfontein.
SGS
is
an
accredited
facility
(T0265)
by
the
South
African
National
Accreditation
System
(SANAS)
for
the
selected
analytical method. Randomly selected check samples (approximately 10% of total samples per
TSF) from MAED were sent to SGS for confirmation. SGS is independent
of Ergo;
and
●
AngloGold Ashanti Limited Chemical Laboratory (Anglo Lab),
located in Carletonville,
analyzed
some
check
samples
for
7L15
TSF
in
2016/2017
as
a
secondary
laboratory
to
MAED.
The
laboratory no longer exists
and was not SANAS accredited.
The laboratory was independent
of
Ergo.
The
slime
material
has
been
previously
processed
and
sample
preparation
only
requires
weighing,
drying,
screening,
splitting
and
milling
before assaying.
Screening
removes
potentially
carbonaceous
and other oversized material to represent the material to
be processed through the metallurgical plant.
1.7
Assays
The laboratories weighed the
samples on receipt
before dry screening
them to remove
foreign material.
The
samples
were
then
dried
at
105
˚
C,
crushed
(80%
passing
2mm),
before
being
riffle
split
and
pulverized to 75µm.
The samples
were then analyzed
to determine the
gold content by
fire assay with
gravimetric
finish
by
MAED
and
Atomic
Absorption
Spectroscopy
(AAS)
finish
by
SGS.
The
lower
detection limit for these
methods is 0.01g/t with
no upper detection limit
for the gravimetric method
and
a 10g/t upper limit for AAS. The lower limit
is relevant to the current project
as the TSFs and sand dumps
consist of
processed
materials
and
are
generally
low-grade,
with
grades
slightly
higher
than
10 to
20
times the detection limit.
The laboratories
were instructed
to use
a 100g
aliquot to
analyze for
gold. Through
the experience
of
the QPs, it
is known that analyzing gold
in low-grade slimes, anything less
than a 100g
aliquot may report
inaccurate results.
Technical Report Summary of the material Tailings Storage
Facilities
4
1.8
Quality Assurance and Quality Control
The laboratories used
in analyzing the samples
have robust internal
quality control checks.
They routinely
insert reference
material (standards and
blanks)
and create
duplicates to
internally check the
accuracy
and precision
of their
assaying techniques.
A batch
is re-assayed
if the
quality control
samples do
not
perform as
expected. The
results of
the quality
control checks
were provided
with the
sample assays
and were all found to be acceptable by the QP.
The
RVN
Group
inserted
certified
quality
control
samples
as
an
additional
check
for
contamination,
precision
and
accuracy.
The
RVN
Group
quality
control
samples
results
were
satisfactory
as
they
generally reported values within the expected ranges.
1.9
Metallurgical Sampling and Testing
The TSFs
were portioned
into logical
sections for
metallurgical testing,
based either
on area,
shape or
elevation. The selected intervals for compositing into the metallurgical test
work samples were taken at
different elevations within the TSF to provide sufficient
material for the test work.
The
“
as
received
”
material
was
blended
and
divided
into
2kg
portions
using
cone
and
quarter
splitting.
Leaching of
“
as received
”
material were
done using
the following
parameters, which
simulates the
existing Ergo leach plant:
●
pH = 10.5;
●
precondition with lime for 1 hour or more to maintain
pH at 10.5;
●
Carbon-in-Leach (CIL) with 15g/l carbon;
●
NaCN addition 0,5kg/t;
●
dissolved oxygen in excess of six parts per million (ppm);
●
leach time eight hours; and
●
all samples were submitted to MAED for gold analysis
.
The metallurgical test work confirms that the material tested can be processed to recover residual gold
from the TSFs assessed via the current Ergo metallurgical
plant process.
Predicted
recoveries
from
the
TSFs
tested
vary
between
30%
and
60%
and
are
dependent
on
head
grade and the nature of the material. These values are typical for gold TSF processing. All the TSFs meet
the requirements for processing through the Ergo
plants.
Technical Report Summary of the material Tailings Storage
Facilities
5
1.10
Mineral Resource Estimate
The
Mineral
Resource
Estimate
for
the
TSFs
and
sand
dumps
were
adjusted
for
depletion
as
at
30 June 2022. The Mineral Resource estimate for all
the TSFs and sand dumps are declared as follows:
●
the point of
reference is
in situ
for all TSFs
and sand
dumps. The TSFs
or sand dumps
themselves
are the reference points;
●
no
geological
or
other
loses
were
applied
as
all
material
is
accessible
and
there
are
no
geological structures.
●
the Mineral
Resource Estimate
is stated
as both
inclusive and
exclusive
of Mineral
Reserves as
defined in Subpart 1300 of Regulation S-K; and
●
Mineral Resource is 100% attributable to DRDGOLD
.
The total
Mineral Resource
Estimate for
Ergo is
presented in
Table 1.1
to Table
1.2. The
changes in
the
Mineral Resource
from June
2021 to
June 2022
are due
to the
depletion of
20.51Mt at
0.33g/t Au
and
minor survey adjustments of 2.94Mt at 0.20g/t Au.
Table 1.1:
Ergo’s Mineral Resource Statement as at 30 June
2022 (Inclusive)
Mineral Resource
Classification
Mineral Resource as at 30 June 2021
(Inclusive)
Mineral Resource as at 30 June 2022
(Inclusive)
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Measured Mineral Resource
282.95
0.31
2.81
266.25
0.31
2.64
Indicated Mineral Resource
574.95
0.25
4.61
568.21
0.25
4.55
Sub-total Measured and
Indicated Mineral Resource
857.90
0.27
7.42
834.45
0.27
7.19
Inferred Mineral Resource
21.32
0.24
0.16
21.32
0.24
0.16
Total Mineral Resources
879.22
0.27
7.58
855.77
0.27
7.35
Source: The RVN Group, 2022
Notes:
1.
Mineral Resources are reported inclusive of Mineral Reserves.
2.
Mineral Resources have been reported in accordance
with the classification criteria of Subpart 1300 of
Regulation S-K.
3.
Mineral Resources were estimated using the USD1,823/oz, ZAR15.60/USD, ZAR914,294/kg
financial parameters and recoveries in Table 11.2.
4.
The reference point for the Mineral Resource is in situ
.
5.
Quantities and grades have been rounded to two decimal
places; therefore, minor computational errors may
occur.
6.
No geological losses were applied to the Mineral Resources.
7.
Attributable Mineral Resource is 100% of the total Mineral
Resource.
Technical Report Summary of the material Tailings Storage
Facilities
6
Table 1.2:
Ergo’s Mineral Resource Statement as at 30 June
2022 (Exclusive)
Mineral Resource
Classification
Mineral Resource as at 30 June 2021
(Exclusive)
Mineral Resource as at 30 June 2022
(Exclusive)
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Measured Mineral Resource
-
-
-
66.04
0.26
0.55
Indicated Mineral Resource
574.95
0.25
4.61
375.41
0.25
3.02
Sub-total Measured and
Indicated Mineral Resource
574.95
0.25
4.61
441.45
0.25
3.57
Inferred Mineral Resource
21.32
0.24
0.16
21.32
0.24
0.16
Total Mineral Resources
596.27
0.25
4.77
462.77
0.25
3.73
Source: The RVN Group, 2022
Notes:
1.
Mineral Resources are reported exclusive of Mineral Reserves.
2.
Mineral Resources have been reported in accordance
with the classification criteria of Subpart 1300 of
Regulation S-K.
3.
Mineral Resources were estimated using the USD1,823/oz, ZAR15.60/USD,
914,294ZAR/kg financial parameters and recoveries in Table 11.2.
4.
The reference point for the Mineral Resource is in situ
.
5.
Quantities and grades have been rounded to two decimal
places; therefore, minor computational errors may
occur.
6.
No geological losses were applied to the Mineral Resources.
7.
Attributable Mineral Resource is 100% of the total Mineral
Resource.
1.11
Mineral Reserve Estimate
The total Mineral Reserve estimate for Ergo is presented in Table
1.3. The changes in the Mineral Reserve
from 30 June 2021 to 30 June 2022 is due to the inclusion of
192Mt at 0.24g/t Au from Daggafontein, the
removal
of
66Mt
at
0.26g/t
Au
from
Grootvlei,
the
depletion
of
20Mt
at
0.33g/t
Au
and
the
survey
adjustments of 2.94Mt at 0.20g/t Au.
Table 1.3:
Ergo’s Mineral Reserve Statement as at 30 June 2022
Mineral Reserve
Classification
Mineral Reserve as at 30 June 2021
Mineral Reserve as at 30 June 2022
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Tone
(Mt)
Au
(g/t)
Contents
(Moz)
Proven Mineral Reserve
29.36
0.295
0.28
200.21
0.33
2.09
Probable Mineral Reserve
253.59
0.311
2.53
192.79
0.24
1.49
Total Mineral Reserves
282.95
0.309
2.81
393.00
0.28
3.58
Source: The RVN Group, 2022
Notes:
1.
Tons and grades were rounded and this may result
in minor adding discrepancies.
2.
Mineral Reserve has been reported in accordance with the
classification criteria defined in the classification criteria
of Subpart 1300 of
Regulation S-K
3.
Mineral Reserve is estimated using the USD1,823/oz, ZAR15.60/
USD and ZAR914,294/kg financial parameters.
4.
A cut-off grade of 0.20g/t has been applied.
5.
No mining losses or dilution has been applied
in the conversion process nor has a mine call factor
been applied.
6.
Tons and grade Run-of-Mine (RoM) as delivered
to the plant.
7.
Attributable Mineral Reserve is 100% of the total Mineral
Reserve.
Technical Report Summary of the material Tailings Storage
Facilities
7
Table 1.4 depicts the Mineral Reserve reconciliation
between 30 June 2021 and 30 June 2022.
Table 1.4:
Mineral Reserve Reconciliation
Source
Tons
(Mt)
Au Grade
(g/t)
Content
(Moz)
Total Mineral Reserve as at 30 June 2021
282.95
0.31
2.81
Depletion through Mining
(20.48)
0.33
(0.22)
Survey Adjustments
(2.94)
0.20
(0.01)
Inclusion of Daggafontein TSF in the LoM Plan
192.79
0.24
1.49
Exclusion of a Grootvlei TSF
(66.04)
0.26
(0.55)
Inclusion of 4 TSFs in the LoM Plan
6.72
0.26
0.06
Total Mineral Reserve as at 30 June 2022
393.00
0.28
3.58
Source: The RVN Group, 2022
Note: Quantities and grades have been rounded to two
decimal places therefore minor computational
errors may occur.
The
various
modifying
factors,
i.e.,
mining,
metallurgical,
processing,
infrastructure,
economic,
marketing, legal, environmental,
and governmental factors,
are discussed in
the following Items
of this
report.
The 30
June 2022
Life-of-Mine (LoM)
plan was
developed for
the Ergo
operations and
is based
on the
Mineral Resource Estimate as at 30 June
2022
together with a set of modifying
factors based on recent
historical
results
and
economic
inputs
provided
by
Ergo.
The
assumptions
applied
in
determining
the
modifying
factors
and
economic
inputs
are
reasonable
and
appropriate.
The
LoM
plan
is sufficient
ly
detailed
to
ensure
achievability
and
is
based
on
historical
achievements.
All
the
inputs
used
in
the
estimation of the Mineral
Reserve have been thoroughly
reviewed and can
be considered technically
robust.
The current mining methods applied
by Ergo are suitable for all TSFs.
No selective mining will occur with
the entire TSF being processed (including Inferred Mineral
Resources).
The Ergo processing
plant targets a
Run-of-Mine (RoM) throughput
between 1.8Mtpm to
2.0Mtpm. The
City Deep
plant has
been reconfigured
to operate
as a
milling and
pump station
and feed
the Ergo
processing plant via
a 50km pipeline.
The City Deep plant
processes material from
mining areas of
the
Central Rand areas of Johannesburg and is scheduled to close in 2027. Mining areas of Germiston, and
some areas of Boksburg are
treated via the Knights plant,
with mining operations scheduled to
close in
June 2024.
An
average
processing
plant
recovery
of
40.9%
has
been
estimated
over
the
19-year
LoM.
The
recoveries are based on metallurgical test work for the various TSFs,
slimes and silted wetland areas that
are scheduled to be mined over the 19-year LoM plan.
The
QP
is
of
the
opinion
that
all
significant
infrastructure
and
logistical
requirements
have
been
considered and
costed. It
is notable
that Ergo
has been
operating for
more than
20 years
and has
a
very good understanding of infrastructural and logistical
requirements.
A gold price
of ZAR914,294/kg is
used to support
the 30 June
2022 Mineral Resource
and Mineral Reserve
statements.
A
gold
price
of
USD1,823/oz
and
an
exchange
rate
of
ZAR15.60:1USD
was
used
in
the
estimation process.
Technical Report Summary of the material Tailings Storage
Facilities
8
The
gold
price
and
exchange
rates
were
considered
reasonable
by
the
QPs
to
support
the
Mineral
Resource and Mineral Reserve estimates as at 30 June
2022.
Mining Rights, Environmental Approvals and Prospecting Rights held
are listed under the Ergo
subsidiary.
Ergo has
numerous Surface
and Prospecting
Rights and
the ownership
of the
surface rights
and mine
TSFs vests
in various
legal entities.
Ergo’s Environment
al Management
Plan (EMP)
encompasses all
the
activities
of Ergo’s
operations
and assesses
the environmental
impacts of
mining
at reclamation
sites,
processing
plants,
TSFs
and
sand
dumps.
It
also
outlines
the
closure
process,
including
financial
provisions.
There are competing ownership
claims on the Grootvlei and Marievale
Complexes, as detailed in Item
3.6. On other TSFs,
there are no legal
challenges to Ergo’s
title that would
prevent operations of any
of
the current mineral rights or mining operations.
A
closure
cost
of
ZAR645
million
has
been
estimated
in
June
2022
for
the
Ergo
operations.
The
QP
is
satisfied that funding for rehabilitation and mine closure is adequate. The QP is satisfied that all material
issues relating to Environmental, Social and Governance
have been addressed in this document.
A total capital of ZAR3.22
billion is scheduled to
support the 19-LoM plan,
as depicted. The breakdown
of capital expenditure indicates that the majority of the capital, ZAR3.14 billion,
is allocated to the Ergo
operation over
the duration
of the
LoM plan
with an
additional
ZAR81.9 million
allocated for
the
City
Deep Complex.
As the
mining at
the Knight
section is
scheduled to
be completed
in 2024
there is
no
allocation
of
capital.
The
level
of
accuracy
for
the
capital
expenditure
is
at
least
to
a
preliminary
feasibility study (PFS) level of accuracy, (i.e., +/-25%) with
a maximum level of contingency of 15%.
The planned average operating cost for the Ergo budget
over the 19-year operations is estimated at a
PFS level of accuracy (i.e., +/-25%) and a total working
cost of ZAR90.86/t.
The 30 June
2022 19-year
LoM plan, which
is the basis
of the Mineral
Reserve estimate,
is scheduled
to
mine a total of 410.33Mt
at 0.28g/t and produce
50,658kg of gold over the
same period. The LoM
plan
includes
17.3Mt
of
material
that
is
treated
on
a
third-party
contract
basis
and
is
not
included
in
the
Mineral
Reserve.
The
economic
analysis
is
based
on
a
LoM
plan
that
is
designed
to
a
PFS
level
of
accuracy
(i.e.,
+/-25%).
The
economic
analysis
conducted
by
the
QP
indicates
a
net
present
value
(NPV) of ZAR2.21
billion after capital
expenditure and taxation
utilizing a discount
rate of 9.48%.
As the
Ergo operations are an on-going
operation with an annual positive
cashflow, the internal rate of return
(IRR) and payback period are not applicable.
Technical Report Summary of the material Tailings Storage
Facilities
9
The
sensitivity
analysis
of
the
Ergo
LoM
model
varies
revenue
(price
and
grade),
operating
cost
and
capital expenditure at 5%
increments above and
below the base case.
The analysis indicates that
the
Ergo operations are
very sensitive to
revenue parameters such as
gold price,
exchange rate, grade and
recovery. In addition, the LoM is also very sensitive to changes in operating costs. The sensitivity
analysis
indicates
that
the
LoM
is
not
overly
sensitive
to
capital
and
therefore, capital
expenditure
should
be
considered
if
the
expenditure
will
reduce
operating
costs or
increase
revenue.
The sensitivity
analysis
indicates that
the achievement
of the
LoM Plan
in terms
of tonnage
is critical
in realizing
the planned
operating costs and being able to mine the individual TSFs at
the planned cut-off grade.
1.12
Permitting Requirements
Ergo
is
one
of
only
a
few
surface
operators
that
holds
Mining
Rights
under
the
MPRDA
over
a
large
portion
of
its
reserves.
The
provisions
of
the
MPRDA,
and
the
definition
of
‘mineral’
had
inadvertently
created
a
gap
in
the
Act
placing
the
‘minerals’
in
certain
TSFs
beyond
the
regulatory
reach
of
the
MPRDA and limiting its competency to issue rights
upon application.
However,
in
terms
of
the
transitional
arrangements
of
the
MPRDA,
which
were
peremptory
upon
the
DMRE in the event that the petitioner met the conditions for conversion from ‘old order’ to
‘new order’,
Ergo was
able to
convert its
old order
rights,
thus extending
its “license
to mine”
into the
dispensation
introduced by the MPRDA. Ergo has also submitted applications
to renew all its Mining and Prospecting
Rights with
the DMRE.
The current
Mining and
Prospecting
Rights have
expired (with
the exception
of
7L4 TSF) but remain in force until such time that the renewal applications
have been granted or refused
by the
DMRE. Water use
licenses are
applied for
as and
when required
to remain
compliant with
relevant
legislation.
Ergo
complies
with
all
the
conditions
for
renewal
and
has
no
reason
to
believe
that
the
submitted
renewals
would not be granted. Ergo is in constant communication with
the DMRE and is submitting the
required information as per their requests to finalize these
renewal applications.
There
are
conflicting
ownership
claims
to
certain
Grootvlei
and
Marievale
TSFs
which
are
detailed
in
Item 3.6.
1.13
Conclusion and Recommendations
The
QP
concludes
that
the
protocols
for
drilling,
sampling
preparation
and
analysis,
verification,
and
security meet industry
standard practices
and are appropriate
for the purposes
of a Mineral
Resource
estimate. The studies
have found that
the Ergo TSFs
have reasonable prospects
for economic extraction.
The QP
is satisfied
with the
Quality Assurance (QA)
developed by
The RVN
Group and
the Quality
Control
(QC) programs implemented as there was no significant
bias in reporting data.
The QP
contends that
the assumptions,
parameters, and
methodology
used for
the Mineral
Resource
estimate are appropriate for the style of mineralization and
deposit type.
There
is
sufficient
information
to
allow
for
decision-making
in
the
future.
The
QPs
recommended
no
additional work.
The
QP
considers
the
conversion
of
Mineral
Resources
to
Mineral
Reserves
to
be
appropriate.
TSFs
reported
in
this
document
have
sufficient
information
to
be
used
in
Mineral
Reserve
estimate
and
demonstrate
economic
viability.
The
modifying
factors
applied
are
considered
appropriate
as
they
Technical Report Summary of the material Tailings Storage
Facilities
10
contain sufficient detail to
support at least a
PFS level of accuracy
(i.e., +/-25%); with a
maximum level
of contingency of 15%.
The significant risks that could affect the Mineral Resource
and Mineral Reserve are:
●
rising electricity prices and the continuity of the Eskom supply
distribution;
●
regulatory approval for the Withok compartment of the Brakpan/Withok
TSF final life design;
●
the sensitivity of some of
the TSFs to the increase
in operating costs and the decrease
in the gold
price;
●
social unrest and social license to operate;
●
supply and cost of water;
●
failure to obtain necessary approvals from the DMRE;
●
competing claims to ownership of certain Marievale
and Grootvlei TSFs;
●
global inflation and rising production costs; and
●
extreme weather.
Technical Report Summary of the material Tailings Storage
Facilities
11
2
Introduction
2.1
Project Background
Ergo Mining
(Proprietary)
Limited (Ergo)
is a
subsidiary
of DRDGOLD
Limited
(DRDGOLD).
DRDGOLD
is
domiciled in South
Africa and listed
on the
Johannesburg Stock Exchange (JSE:DRD)and
New York
Stock
Exchange (NYSE:
DRD).
DRDGOLD, a
South African-based
gold mining
company, has
a 100%
share in
Ergo.
The Tailings
Storage Facilities
’
(TSFs’) Mineral
Resource and
Mineral Reserve
estimates declared
in this
Technical Report Summary (this
Report/TRS) are owned
by Ergo and
are 100% attributable
to DRDGOLD.
The TSFs
covered in
the report
are from
the Crown,
City Deep,
Knights, Ergo,
Marievale and
Grootvlei
Complexes,
and 5A10/5L27 sand
dumps and Daggafontein
TSF. A total
of 19 TSFs
were identified by
Ergo
to be material properties and have been
described extensively in this report. Ergo
has a total of 98 TSFs
inclusive of 79 smaller TSFs and clean-up sites.
The Mineral Resource and Mineral Reserve estimates
contained in this Technical Report
Summary were
compiled
and
reported
by
the
Qualified
Persons
(QPs)
for
DRDGOLD
in
accordance
with
Items
601(b)(96) and 1300 through 1305 of
Regulation S-K (Title 17, Part 229,
Items 601(b)(96) and 1300 through
1305
of
the
Code
of
Federal
Regulations)
promulgated
by
the
Securities
and
Exchange
Commission
(SEC).
This document is the first submission of a Technical Report Summary under Subpart
1300 of Regulation S-
K; thus, it is not an update of a previously filed Technical
Report Summary.
The material TSFs are at different mining stages as presented
below:
●
Crown (3L5, 3L7 and 3L8):
The TSFs are at an advanced
exploration stage, with all
TSFs classified
as Indicated Mineral Resources.
●
City Deep (4L3,
4L4 and
4L6):
The Complex is
at a development
stage with
all TSFs declared
as
Measured Mineral Resources and Proven Mineral Reserves.
●
Knights (4L14 and
4L50):
The Complex
is at
a development stage,
with TSFs
reported as Measured
Mineral Resources and Proven Mineral Reserves.
●
Ergo
(Rooikraal
and
7L15):
The
Complex
is
at
a
production
stage
with
Measured/Indicated
Mineral Resources and Proven/Probable Mineral Reserves
declared.
●
Marievale (7L4, 7L5, 7L6 and 7L7):
The Complex is at a development stage
with TSFs reported as
Measured Mineral Resources and Proven Mineral Reserves.
●
Grootvlei (6L16,
6L17 and
6L17A):
The Complex
is at
an advanced
exploration
stage with
two
TSFs
reported
as
Measured
Mineral
Resources
and
one
TSF
reported
as
Indicated
Mineral
Resources.
●
5A10/5L27
Sand
Dumps:
The
two
sand
dumps
are
joined.
Measured
Mineral
Resource
and
Proven Mineral Reserve
were declared. The
sand dump is
a production
stage through trucking
to Ergo Plant.
Technical Report Summary of the material Tailings Storage
Facilities
12
●
Daggafontein
TSF:
The
TSF
is
at
a
development
stage,
with
a
significant
amount
(192.79Mt)
declared
as
Indicated
Mineral
Resource
and
Probable
Mineral
Reserve.
A
smaller
amount
(21.32Mt) of the material is reported as Inferred Mineral Resource due to inaccessibility because
of the presence of surface water.
2.2
Terms of Reference and Purpose of the Technical Report
Ergo commissioned the
QPs from The RVN
Group (Proprietary) Limited
(The RVN Group) to
compile this
Technical Report Summary to report their Mineral Resource
and Mineral Reserve estimates.
This report
details the
results
of the
evaluation
drilling,
sampling,
assaying, bulk
density
determination,
surveying
and
metallurgical
test
work
and
the
resultant
Mineral
Resource
and
Mineral
Reserve
estimations.
This document reports the
Mineral Resource and Mineral
Reserve estimates for the
material TSFs. The TSFs
in
this
report
are
clustered
into
complexes,
with
the
exception
of
the
5A10/5L27
sand
dumps
and
Daggafontein TSF, which are reported separately
due to their size and location:
●
Crown;
●
City Deep;
●
Knights;
●
Ergo;
●
Grootvlei;
●
Marievale;
●
5A10/5L27;
and
●
Daggafontein.
This report is the first Technical Report Summary for DRDGOLD prepared under the SEC's
Subpart 1300 of
Regulation S-K disclosure requirements.
The effective
date of
the Mineral
Resource and
Mineral Reserve
estimates
for the TSFs
is 30 June
2022.
The QPs noted that there had been no material change to
the information between the effective date
and the signature date of the Report.
Ergo is a South African gold producer,
recovering gold from the retreatment of surface
tailings facilities
located in the Central and Eastern areas of the Gauteng
Province.
The RVN Group is a South African-based mining consulting firm that
provides services and advice to the
local
and
international
mineral
industries.
Ergo
has
retained
The
RVN
Group
since
2016
to
manage
drilling activities,
estimate Mineral
Resources and
Mineral Reserves
and compile
technical reports.
The
QPs from The RVN Group prepared this Technical
Report Summary.
Technical Report Summary of the material Tailings Storage
Facilities
13
2.3
Participants and Areas of Responsibilities
The following
personnel were
nominated to
the project
team, and
their specific
areas of responsibility
are shown in Table 2.1. The qualifications and appropriate experience of the authors are summarized in
Table 2.1.
Technical Report Summary of the material Tailings Storage
Facilities
14
Table 2.1:
List of QPs and their Responsibilities
Personnel
Company
Qualifications
Responsibility
Mpfariseni Mudau,
Pr.Sci.Nat.
The RVN Group
B.Sc. (Hons) Geology,
Graduate Diploma in Mining Engineering,
M.Sc. Mining Engineering,
B.Sc. Applied Mathematics and Statistics,
SACNASP Registration No.: 400305/12
Item
1 to 11 and
20 to 25
Steven Rupprecht,
FSAIMM
The RVN Group
B.Sc. Mining Engineering,
Ph.D. Mechanical Engineering
FSAIMM Registration No.: 701013
Item
1 and
12 to 19
Source: The RVN Group, 2022
The
QP
responsible
for
reporting
and
signing
off
on
the
exploration
activities
and
Mineral
Resource
estimates is Mr Mpfariseni Mudau.
Mr Mudau is a Professional Natural Scientist
(with registration number
400305/12) registered
with
the
South African
Council
for Natural
Scientific
Professions
(SACNASP)
with
more
than
five
years
of
experience
relevant
to
the
drilling,
estimation
and
reporting
of
TSF
Mineral
Resources. Mr Mudau works for The RVN Group and
is independent of Ergo and DRDGOLD.
The QP
with responsibility for
reporting and signing
off of
the Mineral Reserve
estimates is Professor
Steven
Rupprecht.
Professor
Rupprecht
is a
Fellow
of
the
Southern
African
Institute
of
Mining
and
Metallurgy
(SAIMM
with
registration
number:
701013)
with
more
than
five
years
of
experience
relevant
to
the
estimation and reporting of TSF Mineral Reserves. Professor
Rupprecht is an associate of The RVN Group
and is independent of Ergo and DRDGOLD.
2.4
Sources of Information
Most of the technical information utilized for
the preparation of this report was obtained from
the drilling
campaigns
that
The RVN
Group
supervised.
Other
technical
information
and
engineering
data were
sourced
from
Ergo,
their
contractors
and
third-party
reports
available
in
the
public
domain.
These
sources are acknowledged in the body of the report and
listed in Item 24.
Information provided by the registrant upon which the
QPs relied is listed in Item 25.
In
preparing
the
report,
the
QPs
have
relied
upon
contributions
from
a
range
of
technical,
financial,
environmental
and
engineering
specialists
for
the
disciplines
outside
their
expertise.
Based
on
the
support
and
advice
from
the
specialists,
the
QPs
consider
it
reasonable
to
rely
upon
the
information/advice provided.
2.5
Site Inspection
Mr
Mpfariseni
Mudau
visited
the
drilling
projects
on
commencement,
during,
and
completion
of
the
drilling
campaigns.
These
visits
were
conducted
in
2016,
2017,
2018,
2019,
2020,
2021
and
2022.
Mr Mudau
further visited
the sample
sorting and
storage facilities
at the
Ergo processing
plant in
Brakpan.
On
several
occasions,
Mr
Mudau
also
visited
MAED
Metallurgical
Laboratories
(Proprietary)
Limited
(MAED)
and
SGS
South
Africa
(Proprietary)
Limited
(SGS)
where
the
samples
were
prepared
and
analyzed.
Mr Mudau also visited the mining sites on several occasions
.
Technical Report Summary of the material Tailings Storage
Facilities
15
The objectives of the site visits were to:
●
familiarize the QP with the TSFs and the general infrastructure
;
●
inspect the drilling and sampling sites;
●
conduct assessment of sampling methodologies, quality
control processes and data validation;
●
provide training and conduct planned task observations
;
●
validate
the geological logging;
●
inspect the sample storage area and the sample preparation
methods;
●
discuss and agree on the analytical method with
the laboratories;
and
●
collection of database and additional technical
information.
Steven Rupprecht conducted site visits to material and
non-material TSFs in 2020, 2021 and 2022.
2.6
Units, Currencies and Survey Coordinate System
Unless otherwise
stated, all
figures included
in this
report are
expressed in
metric units.
All geographic
coordinates are UTM WGS84 system or LO29 Meridian
.
The elevation Datum is the mean sea level.
All
monetary
figures expressed
in
this
report are
in South
African
Rand
(ZAR) and
United
States
Dollar
(USD).
A point is
used as the
decimal marker, and the
comma is used
for the thousand’s
separator (for numbers
larger than 999).
Unless
otherwise
stated,
the
word
‘
tons
’
denotes
a
metric
ton
(1,000kg).
Table
2.2
presents
the
abbreviations used in the report.
Table 2.2:
List of Abbreviations
Units
Description
%
percentage
˚
degrees
˚
C
Degrees Centigrade
‘
minutes
“
seconds
µm
Micron
3D
three-dimensional
AAS
Atomic Absorption Spectroscopy
AMD
acid mine drainage
AMIS
African Mineral Standards
amsl
above mean sea level
Anglo Lab
AngloGold Ashanti Limited Chemical Laboratory
Au
gold
CIL
Carbon-in-Leach
cm
centimeter(s)
CoV
Coefficient of Variation
CRM
Certified Reference Material
Crown Mines
Crown Mines Limited
DMRE
Department of Mineral Resources and Energy
DRDGOLD
DRDGOLD Limited
Technical Report Summary of the material Tailings Storage
Facilities
16
Units
Description
EIA
Environmental Impact Assessment
EMP
Environmental Management Plan
EMPr
Environmental Management Program
Ergo
Ergo Mining (Proprietary) Limited
ERPM
East Rand Proprietary Mines Limited
Eskom
Electricity Supply Commission
g
gram(s)
g/l
grams per liter
g/t
grade grams per ton
Geografix
Geografix Surveys CC
GPS
Global Positioning System
ha
hectares = 100m-by-100m
HRD
Human Resource Development
IDW
Inverse Distance Weighting
InSAR
Interferometric Synthetic Aperture Radar
IRR
internal rate of return
ISO
International Organization for Standardization
JSE
Johannesburg Stock Exchange
kg
kilograms = 1,000 grams
kg/t
kilograms per ton
km
kilometer(s) = 1,000 meters
km
2
square kilometers
koz
kilo ounces= 1,000 ounces (troy)
kt
kilotons
ktpm
kilotons per month
LED
Local Economic Development
liter
Metric unit of volume = 1,000cm
3
LoM
Life-of-Mine
m
meter(s)
m
2
square meters
MAED
MAED Metallurgical Laboratories (Proprietary) Limited
mamsl
meters above mean sea level
mm
millimeter(s) = meter/1000
Moz
Million ounces (troy)
MR
Mining Right
Mt
Million metric tons
Mtpa
Million tons per annum
MWP
Mining Works Program
NaCN
sodium cyanide
NERSA
National Energy Regulator of South Africa
NN
Nearest Neighbor
NNR
National Nuclear Regulator
NPV
net present value
NYSE
New York Stock Exchange
oz
Troy ounces = 31.1034768 grams
pH
quantitative measure of the acidity or basicity of a solution
ppm
parts per million
Technical Report Summary of the material Tailings Storage
Facilities
17
Units
Description
PR
Prospecting Right
PWP
Prospecting Work Program
QA
Quality Assurance
QC
Quality Control
QP
Qualified Persons
RC
Reverse Circulation
RoM
Run-of-Mine
SANAS
South African National Accreditation System
SCADA
supervisory control and data acquisition
SEC
Securities and Exchange Commission
SGS
SGS South Africa (Proprietary) Limited
S-K 1300
Subpart 1300 of Regulation S-K under the U.S. Securities Exchange Act of 1934
SLP
Social and Labor Plan
t
metric ton = 1,000 kilograms
t/m
3
density - ton per cubic meter
TCTA
Trans-Caledon Tunnel Authority
The RVN Group
The RVN Group (Proprietary) Limited
this Report
Technical Report Summary
tons
metric tons = 1,000 kilograms
TPMS
Tailings Performance Management System
USD
United States Dollars
WGS84
World Geographic System 1984
WUL
Water Use License
ZAR
South African Rand
2.7
Independence
The QPs or The RVN Group
received a fee for preparing
this Technical Report Summary in
accordance
with standard professional
consulting practice. The
QPs or The RVN
Group will receive
no other benefit
for the preparation of this report.
Neither QPs, The RVN Group, nor
any of its employees and
associates
employed in the
preparation of
this report has
any pecuniary
or beneficial interest
in Ergo, DRDGOLD
,
or their associates.
The QPs consider
themselves independent.
Technical Report Summary of the material Tailings Storage
Facilities
18
3
Property Description
3.1
Location and Operations Overview
Ergo is
reclaiming
TSFs in
the City
of Johannesburg
and the
City of
Ekurhuleni,
Gauteng, South
Africa.
The Crown and City
Deep Complexes are located
in the City of
Johannesburg while all
other TSFs and
the sand dumps are located in the City of Ekurhuleni,
as shown in Figure 3.1.
This TRS covers a total of 18 material TSFs of varying sizes and
one sand dump.
The smaller TSFs or clean-
up sites (79
in total) are
not extensively
covered in this
report for various
reasons: they are
not material
as most are too small
while others are not part of
an immediate plan to be
included in the Life-of-Mine
plan
by
Ergo
(e.g.,
Fleurhof
Complex).
The
18
material
TSFs
and
one
sand
dump
contribute
approximately 89% of the total Mineral Resource, while the remaining 79 smaller TSFs and clean-up sites
only
contribute
11%
to
the
total
Ergo
Mineral
Resource
estimates.
Of
the
total
Ergo
Mineral
Reserve
declared,
92%
contribution
by
tonnage
is
from
the
material
properties.
Thus,
Ergo
considers
the
79
smaller TSFs and clean-up sites not material (Figure 3.2).
The sand dumps (5A10 and
5L27) are combined to form one
elongated structure of varying heights. The
two small
dumps on
the north
and east
are known
as 5L27
and the
center sand
dump is
5A10. These
dumps are joined and
have similar properties.
They were modelled as 5A10/5L27
but then separated for
reporting Mineral Resource estimate.
Of the
total material
properties,
18 are
slime TSFs
and one
is a
sand dump
(5A10/5L27). Slime
is a
very
fine material, while sand is course-grained.
The
areas
occupied
by
the
18
material
TSFs
and
a
sand
dump
are
shown
in
Table
3.1.
Engineering
parameters and topography determined the size and
shapes of the properties at
the time of deposition
of the waste products from the respective processing
plants.
Technical Report Summary of the material Tailings Storage
Facilities
19
Table 3.1:
Footprint Areas of the Material TSFs
TSF
Centre Coordinates
Area
(ha)
Maximum Height
(m)
Crown
3L5 (Diepkloof)
26
0
13’34.95”S, 27
0
57’09.70”E
130.00
67.50
3L7 (Mooifontein)
26
0
13’35.85”S, 27
0
13’35.85”E
87.00
88.50
3L8 (GMTS)
26
0
14’23.75”S, 27
0
58’07.91”E
147.00
94.50
City Deep
4L3
26°13'51.72"S, 28° 5’50.63”E
36.61
40.50
4L4
26°13’59.91”S, 28° 6’9.99”E
23.81
16.50
4L6
26°13’59.56”S, 28° 7’15.02”E
27.15
19.50
Knights
4L14
26°12'23.76"S, 28° 8'54.38"E
10.27
37.50
4L50
26°15'18.78"S, 28°13'8.60"E
68.03
40.50
Ergo
Rooikraal
26
0
21’48.16” S, 28
0
17’40.88”E
141.04
47.50
7L15
26°19'49.59"S, 28°24'46.01"E
73.28
37.50
Marievale
7L4
26°19'30.94"S, 28°30'5.07"E
133.48
25.00
7L5
26°19'55.08"S, 28°30'3.08"E
26.91
22.50
7L6
26°19'56.20"S, 28°30'22.96"E
46.73
34.50
7L7
26°20'51.49"S, 28°30'5.43"E
47.00
13.50
Grootvlei
6L16
26°14'31.94"S, 28°28'55.51"E
112.13
31.50
6L17
26°13'18.99"S, 28°29'23.20"E
110.02
40.50
6L17A
26°14'0.25"S, 28°29'42.67"E
85.05
25.50
5A10/5L27
5A10/5L27
26°13'9.79"S, 28°23'51.84"E
202.00
68.00*
Daggafontein
Daggafontein TSF
26
0
17’56.48” S, 28
0
31’55.10”E
462.21
64.50
Total Area (ha)
1,969.72
Source: The RVN Group, 2022
Note
:
*estimated height as drilling could not reach the base
of the sand dump, only drilled up to 52.5m
.
Technical Report Summary of the material Tailings Storage
Facilities
20
Figure 3.1: Location of the Material TSFs and
Infrastructure (the material properties of Ergo)
Technical Report Summary of the material Tailings Storage
Facilities
21
Technical Report Summary of the material Tailings Storage
Facilities
22
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
23
Figure 3.2:
Location of the Material Properties in Relation
to the Smaller TSFs and Clean-up Operations
Technical Report Summary of the material Tailings Storage
Facilities
24
Technical Report Summary of the material Tailings Storage
Facilities
25
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
26
Other material properties of Ergo include:
●
Knights
Plant;
●
Ergo Plant;
●
Brakpan/Withok TSF;
●
pump stations;
●
a network of pipelines;
●
City Milling Plant;
●
Central Water Facility;
and
●
solar power project.
3.2
Mineral Rights Conditions
TSFs are in most instances
considered movable, and capable
of being owned under
the common law
separately from land. As such they are
distinguishable from underground minerals, which can no longer
be
individually
owned in
South African
but in
respect
of which
the
Department
of
Mineral
Resources
and Energy (DMRE)
may issue Mining Rights
in terms of the
MPRDA of 2002 (MPRDA),
as amended. The
construct of the MPRDA
caused the minerals in
certain TSFs to therefore
fall outside the regulatory reach
of the
MPRDA.
The transitional
arrangements of
the MPRDA
provided for
existing operations
however,
to convert
old order
rights (Mining
Licenses held
under the
previous dispensation)
to new
order rights.
Ergo successfully
converted its
old order
licenses to
Mining Rights,
and is
seeking to
consolidate them
into
a
single
right.
Now,
in
terms
of
reserves
in
TSFs
over
which
there
were
no
old
order
rights,
Environmental Approvals
are obtained
from the
DMRE for
the retreatment
of such
TSFs –
a somewhat
pragmatic, yet administratively competent means of
overcoming the drafting gap in the MPRDA.
For
an
exploration
project,
a
Prospecting
Right
(PR),
valid
for
five
years,
is
issued,
and
for
a
mining
operation, a Mining Right (MR)
valid for up to 30
years,
is issued. The PR, which
is conducted in terms of
a Prospecting Work Program (PWP), is renewable for a
further three years. The MR is undertaken in
terms
of
the
Mining
Works
Program
(MWP),
Social
and
Labor
Plan
(SLP),
and
an
approved
Environmental
Management
Program
(EMPr)which
can
be
renewed
for
a
further
30
years.
A
PR
or
MR
may
be
cancelled or suspended subject to Section 47 of the
MPRDA.
The
MPRDA
makes
provisions
relating
to
the
ownership
and
Broad-Based
Socio-Economic
Empowerment
Charter.
A
shareholding,
equity,
interest
or
participation
in
the
mining
right
or
joint
venture,
or
a
controlling
interest
in
a
company/joint
venture
may
not
be
encumbered,
ceded,
transferred,
mortgaged,
let,
sublet,
assigned,
alienated,
or
otherwise
disposed
of
without
the
written
consent of the Minister, except in the case of a change
of controlling interest in listed companies.
The SLP is submitted to
the DMRE every five
years for approval, while
the SLP’s annual progress
report is
submitted annually to the DMRE.
The Environmental Management Plan (EMP) and Water Use License (WUL) are assessed for compliance
annually.
Technical Report Summary of the material Tailings Storage
Facilities
27
3.3
Mineral Title
Ergo title in its TSFs is vested
in either common law ownership
or private treaty and it
holds either Mining
and
Prospecting
Rights
as presented
in
Table
3.2 or
Environmental
Approvals
in
respect
of the
same.
Ergo has submitted applications
for the renewal of its mining
rights and prospecting rights. The
renewal
applications
were
made
to
the
DMRE
on
different
dates
per
mining
right.
Ergo
is
in
the
process
of
a
consolidation of
its mining
rights and
as such
has applied
to extend
the mining
period for
a further
30
years
through
its
consolidated
mine
works
program.
The
period
of
30
years
is
the
maximum
period
allowable for a Mining Right renewal as detailed in
the MPRDA, as amended.
This report has considered Section 24(5) of the MPRDA, as amended:
“
A mining right in respect of which
an application for renewal has
been lodged shall despite its expiry
date remain in force until such time as such application has
been granted or refused.
”
The same applies to the prospecting right (section18(5)
of the mentioned Act).
Freehold landowners
are presented
in Table 3.3.
Ergo owns a
significant portion
of freehold where
the
TSFs and sand dumps are located. Where Ergo
does not own the property, use and
access agreements
are in place
with third-party landowners,
with the exception
of the landowner
on which certain
of the
Marievale dumps are situated. Access to the TSFs for Prospecting Right purposes is enabled through the
provisions in the MPRDA.
Table 3.2:
Mineral Rights Information as at 30 June 2022
Complex
Permit
Holder
Permit Type
Reference
Number with
the DMRE
Expiry Date
Renewal
Submission
Application
Date
Renewal
Reference
Number with
the DMRE
Crown
Ergo
Mining Right
GP184MR
20/06/2014
24/03/2014
GP 10022 MR
City Deep
Ergo
Mining Right
GP185MR
20/06/2014
24/03/2014
GP 10023 MR
Knights
Ergo
Mining Right
GP187MR
20/06/2018
13/03/2018
GP 10067 MR
Ergo
Ergo
Mining Right
GP158MR
27/10/2021
23/07/2021
GP 10097 MR
Marievale (7L4)
Ergo
Prospecting Right
GP10348
19/02/2022
Not
applicable
Not
applicable
Marievale (7L5,
7L6 and 7L7)
Ergo
Common Law
Ownership
Not
applicable
Not
applicable
Not
applicable
Not
applicable
Grootvlei
Ergo
Prospecting Right
GP10044PR
21/04/2019
28/03/2019
GP 10592 PR*
5A10/5L27
Ergo
Mining Right
GP158MR
27/10/2021
23/07/2021
GP 10097 MR
Daggafontein TSF
Ergo
Mining Right
GP158MR
27/10/2021
23/07/2021
GP 10097 MR
Source: DRDGOLD, 2022
Table 3.3:
Land Tenure Information
Reclamation Sites
Surface Rights Owner
Crown Complex
Ergo and Innovative Property Solutions(iPROP)
City Deep Complex
Ergo and IPROP
Knights Complex
Ergo, Abland, Living Africa and EMM
Technical Report Summary of the material Tailings Storage
Facilities
28
Ergo Complex
Ergo and Ekurhuleni Metropolitan Municipality
Marievale Complex
Ergo, Ekurhuleni Metropolitan Municipality, Scarlet Sun and STI Consulting
Grootvlei Complex
Ekurhuleni Metropolitan Municipality and various private owners
5A10/5L27 Sand Dump
Marcon Group
Daggafontein TSF
Ergo
Source: DRDGOLD, 2022
3.4
Violation and Fines
Ergo has no fines resulting from violating the mineral rights
conditions.
3.5
Royalties
Ergo is not required to pay
royalties to the State, nor
does it receive royalties
from any other operation.
Royalties
in
South
Africa
are
guided
by
the
Mineral
and
Petroleum
Resources
Royalty
Act,
2002
(Act
No. 28 of 2008) (MPRRA).
Ergo does not pay
royalty on the retreatment of
TSFs and sand dumps as
the treatment of TSFs
and sand
dumps does not trigger the requirement to pay royalties
.
3.6
Legal Proceedings and Significant Encumbrances to the Property
The QP was
advised by Ergo
that there are
no material legal
challenges concerning its
Mineral Resource
and Mineral Reserve, except for Grootvlei and
Marievale Complexes. The QPs find it reasonable
to rely
on the legal opinion provided by Ergo.
From the
documentation reviewed
and input
by the
relevant Technical
Specialists, the
QPs could
not
identify
any
significant
factors
or
risks
with
regards
to
the
title
permitting,
surface
ownership,
environmental
and
community
factors
that
would
prevent
the
evaluation
or economic
extraction
of
the
TSFs.
The
QPs
were
assured
that
Ergo
Mining
complies
with
all
title
and
environmental
permitting
requirements.
The
QPs
were
informed
by
Ergo
Mining
that
no
significant
factors
or
risks
might
affect
access,
title,
or
the
right
or
ability
to
perform
work
on
the
TSFs,
except
for
Grootvlei
and
Marievale
Complexes.
Grootvlei Comp
lex:
Ergo
has submitted
a renewal
application
of its
prospecting
rights over
Grootvlei
dumps
6L16,
6L17
and
6L17A
to
the
DMRE.
During
the
2022
financial
year, an
external
party
raised
a
conflicting claim of
common law ownership of
6L16, 6L17 and
6L17A TSFs.
Although the claim
was based
on common law ownership and
no attempt has been made
to set aside the prospecting
rights over the
TSFs, the Grootvlei
TSFs have been
excluded from the
Mineral Reserves statement
and the Life-of-Mine
(LoM) plan but included in the Mineral Resources statement.
Marievale
Complex:
Ergo
acquired
the
7L5,
7L6
and
7L7
TSFs
in
terms
of
a
written
notarial
executed
deed of sale during
2019 and took
possession of the
TSFs on 8 April
2019. It has since
also obtained the
requisite
National
Environmental
Management
Act,
1998
(Act
No.
107
of
1998)
(NEMA)
regulatory
approvals to
retreat the
said TSFs.
During the
2022 financial
year, the
owner of
the land
on which
7L5,
7L6 and 7L7 are situated, an estimated 36,524t out of the total 54,114t comprising the Marievale cluster,
notified Ergo that in its view, the said TSFs had acceded to the land and that it
had become the owner
of the TSFs. Ergo disputes the claim of legal title and
the matter is to be referred to arbitration.
Technical Report Summary of the material Tailings Storage
Facilities
29
All ownership requirements were met when the TSFs were purchased by Ergo and therefore the TSFs are
still included in the Mineral Reserves. Whilst Ergo has received confident legal advice on the merits of its
claim,
in the
event
that the
arbitration
goes against
Ergo,
its Mineral
Reserves
will
reduce by
35.52Mt
(0.35Moz at
0.29g/t). Inasmuch
as it
then enters
into a
commercial arrangement
with the
land-owner,
the
financial
benefit
of
this
portion
of
the
Marievale
cluster
will
be
reduced
by
whatever
benefit
is
agreed to in favor of the land-owner.
Ergo has
a submitted
renewal application
to the
DMRE for
the prospecting
rights it
holds over
7L4 TSF.
The entity (who
holds common law
ownership rights over
the land on
which the TSF is
situated and the
TSF itself) has agreed to relinquish ownership in favor of Ergo, provided
that Ergo undertakes to:
●
make a notional amount payment;
●
suitably remove the TSF; and
●
rehabilitate the land.
A draft contract stipulating the terms of such agreement is awaiting
final signature.
4
Accessibility, Climate, Local Resources, Infrastructure and Physiography
4.1
Topography, Elevation and Vegetation
The project areas fall
in the Grassland Biome
of South Africa. The
Grassland Biome is
found on the high
central plateau of South Africa and the inland areas of Kwazulu
-Natal and the Eastern Cape.
The topography is mainly flat and elevation ranges between
1,560mamsl and 1,700mamsl.
Natural
vegetation
for
the
project
is
limited
to
areas
outside
the
urban
footprint.
Within
the
urban
environment where most of the TSFs are to be reclaimed
,
little vegetation occurs in its natural state.
The TSFs
and
sand
dumps
are
situated in
highly
urbanized
and
industrialized
areas
with
limited
fauna
and flora. The TSFs are man-made and the trees and grasses on the TSFs have been planted to prevent
dust and erosion from the TSFs.
4.2
Access, Towns and Regional Infrastructure
The TSFs
and sand
dumps
are situated
in the
Gauteng Province
of South
Africa, Gauteng
is the
most
industrialized
province
in
South Africa
and
the
infrastructure is
adequate.
All
the
regional
and
on-site
infrastructure that is required for mining is well established. There
is a good supply chain for all necessary
consumables and equipment in or near the mine sites.
The areas surrounding
the mine sites
have good health
facilities (i.e., public
and private hospitals)
and
education facilities (i.e., ranging from pre-primary
to secondary and tertiary education levels).
A good
road transportation system
can be
found in
the area.
The TSFs
and sand
dumps are
well serviced
by highways, paved
regional roads and a
network of dirt tracks
that the Ergo utilized
to access mining
and project visits. The QPs consider access to the
TSFs to be in good condition. For international supplies
Technical Report Summary of the material Tailings Storage
Facilities
30
or travel, the OR Tambo and Lanseria International Airports, in Kempton
Park and Lanseria respectively,
are well-positioned to service Ergo.
Tele-communication on the
TSFs and sand dumps
is good for all major
network providers. Most parts
of
the
project
areas
are
fully
covered
by
the
third
or
fourth
generation
(3G
or
4G)
wireless
mobile
telecommunications technology. Other areas are
now covered by high-end 5G technology.
Item 15 presents the infrastructure in more detail.
4.3
Climate
A summer rainfall climate prevails
in the areas. Summer rain
occurs mainly in the form of
thunderstorms
with
a
mean
annual
precipitation
of
approximately
680mm,
and
evaporation
is
about
1,800mm
per
year. Winds
are generally
light and
blow predominantly
from the northwest.
Winters are
cold and
dry.
Extreme
weather
conditions
occur
in
the
form
of
frost
(2
to
20
occurrences
per
annum)
and
the
occasional hailstorm.
The
average
annual
temperature
for
the
year
is
approximately
19˚C,
with
average
maximum
temperatures ranging between 22˚C
and 32˚C and average minimum
temperatures ranging between
2˚C
and
18˚C.
The
hottest
months
are
from
December
to
February.
During
April
and
May,
there
is
a
noticeable drop
in temperature,
which signals
the commencement
of winter.
The coldest
months are
June and July. Rains and temperature have minimal effects
on operations.
The area generally has
a high evaporation rate
in the summer months
from November to January.
This
gives rise to
high relative humidity.
Evaporation is greater
in summer than
in winter due
to higher ambient
temperatures.
There are no long-term associated climatic risks, other
than those associated with climate change and
global warming, and the operating season is year-round.
4.4
Infrastructure and Bulk Service Supplies
The TSFs and sand
dumps are situated
in the well-developed
province of Gauteng
and have the
most
major supplies. All the
regional and on-site infrastructure that
is required for mining and
processing is well
established. There is
a good supply
chain for all
necessary consumables and
equipment in or near
the
mine sites. Section 15 of this report details the infrastructure
relevant to Ergo.
The TSFs and sand dumps are located near hospitals
offering basic and advanced medical care.
The project
areas are supplied
with bulk
electricity from the
regional grid supplied
by Eskom,
the national
power supplier, or by the local municipality. Like most parts of South Africa, the operations are affected
by occasional load shedding implemented by Eskom
during periods of constrained power generation.
Water to the TSFs and related infrastructure is supplied by Rand
Water. Ergo recycles most of the water.
4.5
Personnel Sources
Where mining activities take place,
Ergo has commissioned contractors to
conduct mining and secure
the TSFs.
Where there
are no
mining activities,
Ergo has
employed contractors
to maintain
the TSFs
(to
Technical Report Summary of the material Tailings Storage
Facilities
31
minimize dust and monitor water levels on the TSFs and sand dumps) and security companies to secure
the properties.
Ergo employees conduct site inspections
on a regular basis of the project TSFs and sand dumps.
Should additional
employees
be required,
the surrounding
areas have
a large
semi-skilled
and skilled
workforce.
The
cities
of
Johannesburg
and
Ekurhuleni
have
a
large
source
of
talent
for
trades
and
technical management.
The majority of
employees hired
by Ergo are
sourced from Gauteng
Province, where
all the properties
are situated. Contractors and
specialist consultants are also
predominantly based in Gauteng Province.
Technical Report Summary of the material Tailings Storage
Facilities
32
5
History
5.1
Ownership
Anglo American Corporation
commissioned the Ergo
facility (processing plant)
on the
East Rand in
1977.
The objective was to recover gold, uranium and produce sulfuric acid from surface tailings material via
a metallurgical
flotation process.
In 1977
a carbon
in leach
(CIL) plant
was added.
In 1990,
when the
uranium market collapsed, the uranium plant
and the larger of the two acid
plants were closed down.
In 1998
Ergo became
part of
Anglo Gold
Limited (later
Anglo Gold
Ashanti Limited).
In 2005
Ergo was
closed down.
In 2007, Ergo (Pty) Limited was formed as a
joint venture between DRDGOLD and Mintails to re-establish
the tailings
treatment
operations.
A year
later (2008)
re-commissioning
of the
plant
started, and
Ergo
acquired the Mintails’
stake in the
gold recovery phase
of the project.
In 2009 a
second feed line
was
brought into the Ergo plant
from the Elsburg TSFs
and the plant capacity
doubled to 1.2 Mt
per month.
In 2010, DRDGOLD acquired the balance of Mintails
’
interest.
5.1.1
Crown Complex
Crown
Mines
Limited
(Crown
Mines),
previously
known
as
Rand
Mines
(Milling
and
Mining)
Limited,
belonged
to
Rand
Mining
Proprietary
Group,
which
commenced
retreatment
operations
in
1982.
At
least 90% of the
Crown Complex material was deposited onto
the Crown TSF Complex Facility by
Crown
Gold Recoveries,
which retreated
processed material
originally mined
from the
historical mines
in the
area. The Crown complex is situated on the farm
Mooifontein 225-IQ.
5.1.2
City Deep complex
City Deep belonged
to Rand Mines
(Milling and Mining) Limited
and fell under
the same group
as Crown
Gold Recovery. Records indicate
that in 1986 City Deep Complex
belonged to City Deep Rand Mines.
Most
of
City
Deep
TSFs
are
located
on
the
farms
Elandsfontein
107-IR,
Kliprivierfontein
106-IR
and
Doornfontein 92-IR.
5.1.3
Knight Complex
Most
of
the
TSFs
in
the
Knights
complex
were
previously
owned
by
Simmer
and
Jack
dating
back
to
1986. Witwatersrand Gold Mine owned other TSFs.
5.1.4
Ergo Complex
The Ergo
Complex was
created
by East
Rand Proprietary
Mines Limited
(ERPM) around
1958. ERPM
in
Boksburg
was
established
more
than
125
years
ago
as
an
underground
gold
mining
operation
and
produced gold
from 1896
to 2008.
ERPM had
approximately 15
shafts in
the Elsburg
area, which
were
the primary sources of the
tailings material deposited onto TSFs
4L47/48/49 and 50. The Ergo
complex is
situated on the farms Klippoortje 110-IR and 112-IR.
Technical Report Summary of the material Tailings Storage
Facilities
33
5.1.5
Marievale Complex
Marievale
Complex
was
previously
owned
by
Gencor
Limited
(General
Mining
Union
Corporation)
(Gencor) and operated
by Marievale Consolidated
Mines. The primary
commodity was
gold, and the
secondary
commodity
was
silver.
The
first
year
of
production
was
1939.
Mining
stopped
in
1998.
The
Marievale complex is located on the farm Vlakfontein
281-IR.
5.1.6
Grootvlei Complex
Grootvlei was
previously owned
by Gencor
and operated
by Grootvlei
Proprietary Mines
Limited from
1967 to 1981 at
an average grade
of 5g/t of gold.
The registered owner in
1986 was DUMPCO
Limited.
Mining stopped in 2005. Grootvlei is located on the farm Grootvlei
124-IR.
5.1.7
5A10/5L27
The Consolidated Modderfontein Mine deposited mine tailings on the 5A10/5L27 sand dump during
the
1980s. Before then, the sand dump was owned by Government
Gold Mine.
5.1.8
Daggafontein TSF
Daggafontein
TSF
was
previously
owned
by
Daggafontein
Mines.
Tailings
deposition
onto
the
TSF
commenced around 1982
and ceased around
2002 when the mine
ceased operations. Currently,
the
TSF is owned by Ergo.
5.2
Construction of the TSFs and Sand Dumps
The TSFs
were constructed in
accordance with
the then
Chamber of
Mines guidelines and
best practices
at the
time. The
guidelines provided
for a
starter wall,
toe drain
and blanket
drain. Gravity
penstocks
were
provided
on
all
TSFs,
which
were
subsequently
replaced
with
elevated
penstocks
during
their
operations. The final design heights for
a ‘typical’
TSF operated using day-walls were
generally between
30m and 100m.
All the TSFs were constructed as upstream TSFs. Upstream TSFs need to be raised slowly to
allow the solid
tailings time to dry and consolidate enough to support
a new level of the TSF.
The sand dump material was deposited by trucks
or cocopans.
Technical Report Summary of the material Tailings Storage
Facilities
34
Table 5.1
presents the
history and
status of
TSFs and
the sand
dump. The
TSFs and
the sand
dump are
considered old, and the properties have been dormant
for a considerable number of years.
Table 5.1:
History and Status of the TSFs and Sand Dump
TSF/Sand Dump
Commissioned
Date
Decommissioned
Date
Status as at
30 June 2022
Age since becoming
Dormant (Years)
Crown
3L5
+/-1920
2009
Dormant
12
3L7
Dormant
3L8
Dormant
City Deep
4L3
1965
1984
Development
37
4L4
Development
4L6
Development
Knights
4L14
1960
2000
Dormant
21
4L50
1968
1998
Mining
NA
Ergo
Rooikraal
1985
2012
Development
9
7L15
1964
1986
Dormant
35
Marievale
7L4
1964
1998
Dormant
23
7L5
1964
1998
Dormant
23
7L6
1964
1998
Dormant
23
7L7
1964
1998
Dormant
23
Grootvlei
6L16
1964
2005
Dormant
16
6L17
2005
Dormant
16
6L17A
2005
Dormant
16
5A10/5L27
5A10/5L27
1960
1986
Mining
NA
Daggafontein
Daggafontein
1970
2003
Dormant
17
Source: DRDGOLD, 2022
5.3
Previous Exploration and Mine Development
5.3.1
Previous Evaluation Drilling
Previous evaluation drilling
was completed on the
TSFs in the 1970s
by Anglo-American, and
from 2006
to
2008
by
Ergo
and
Mintails
SA
(Proprietary)
Limited.
The
QP
was
made
aware
of
these
activities,
however the
QP did
not use
data acquired
before 2008
in this
report as
data quality
assessment and
validation could not be performed.
5.3.2
Previous Development
In 1976,
the construction
of the processing
plant and
associated infrastructure
commenced and
Ergo
formally came into production on 25 February 1978.
Technical Report Summary of the material Tailings Storage
Facilities
35
Table 5.2 presents Ergo’s production data over the last
five years.
Table 5.2:
ERGO Production History
Date
Tons Mined
(Mt)
Yield Au
(g/t)
Gold Produced
(kg)
Gold Produced
(koz)
30 June 2018
24.3
0.19
4,679
150
30 June 2019
23.2
0.19
4,493
144
30 June 2020
*
20.2
0.20
3,989
128
30 June 2021
23.0
0.19
4,263
137
30 June 2022
22.1
0.19
4,156
134
Source: DRDGOLD, 2022
Note: *production was affected by COVID-19 national
lockdown.
Technical Report Summary of the material Tailings Storage
Facilities
36
6
Geological Setting, Mineralization and Deposit
6.1
Regional Geology
The TSFs are man-made features, and mineral distribution reflects the artificial nature
of the deposit. The
materials are
the waste
products (tailings)
of the
mining and
metallurgical process
recovery from
the
Witwatersrand and Transvaal Supergroups gold deposits.
These
tailings
consist
predominantly
of
quartz,
lesser
amounts
of
mica,
chlorite,
chloritoid,
pyrite
(1% to 2%) and low concentrations of gold, uranium
and sulfur.
Gold was discovered in the conglomerates of the Witwatersrand
sedimentary basin in about 1886.
The Witwatersrand
Supergroup is
aerially and structurally
related to
the underlying Dominion
Reef System
and the
overlying
Ventersdorp
System.
The Supergroup
is an
elongated
sedimentary
basin stretching
some 320km in a north-easterly direction and
160km in a north-westerly direction. The
upper portions of
the Witwatersrand Supergroup contain quartz conglomerates that have been mined for their gold
and
uranium contents.
The Transvaal Supergroup is a
stratigraphic unit consisting of
clastic sediments, carbonates, banded iron
formations and volcanics
younger than the
Witwatersrand Supergroup.
It occasionally
directly overlies
the
gold-bearing
conglomerates
of the
Witwatersrand
Supergroup
where
the
Ventersdorp
Volcanics
have been eroded or were not developed. At the base of
the Transvaal Supergroup is a conglomerate
layer, the Black Reef, that has been mined for gold.
The operations
are situated
in the
Witwatersrand Central
Rand and
East Goldfields.
The East
Goldfield
are linked
to the
Central
basin across
a large
monoclinal
structure, the
Springs
Monocline.
The major
economic
horizons
mined
were
the
South
Reef
together
with
Main
Reef,
Main
Reef
Leader
and
the
Elsburg and Kimberley Reefs. The Black Reef, where
mineralized,
was also mined in the area.
6.2
Mineralization, Local and Property Geology
The TSFs
has been processed
through metallurgical plants
that eject a
residue (tailings) which
is relatively
uniform in terms
of gold mineralization when
compared with the
natural deposit from
which the material
is derived. The variation
between gold grades is
small as the
process residue dump was
constructed in
layers/benches.
Grade
variation
primarily
follows
variations
in
the
processing
and,
to
a
lesser
extent,
primary deposits characteristic. The gold mineralization
is fairly well distributed throughout the TSF.
The TSFs are the by-product
of the mineral recovery
process. They took the
form of a liquid slurry
made
of fine mineral
particles
–
created when mined ore
was crushed,
milled and processed. The
tailings
were
pumped to
the TSFs which
were constructed
using earth dam
s. As the
residue of
the tailings
gradually
drained
and
became
compacted,
grass
and
other
vegetation
were
planted
to
rehabilitate
the
environment.
Technical Report Summary of the material Tailings Storage
Facilities
37
The TSFs and sand dumps evaluated in this report originated from different sources or processing plants,
as shown in Table 6.1.
Table 6.1:
Origin of the TSF and Sand Dump Material
TSF/Sand Dump
Source Mine
Mined Reef
Crown Complex
3L5
Crown Mines
Main Reef
3L7
Crown Mines
Main Reef
3L8
Crown Mines
Main Reef
City Deep Complex
4L3
City Deep Gold Mine (Proprietary) Limited
Kimberley Reef
4L5
City Deep Gold Mine (Proprietary) Limited
Kimberley Reef
4L6
City Deep Gold Mine (Proprietary) Limited
Kimberley Reef
Knights Complex
4L14
Simmer and Jack Gold Mine
Black Reef
4L50
Witwatersrand Gold Mine
Black Reef/Elsburg
Ergo Complex
Rooikraal
Knights Plant
Residue from Knights Plant
7L15
Vlakfontein Mine
Black Reef
Marievale Complex
7L4
Marievale Consolidated Mine
Kimberley Reef, Nigel Reef and Main
7L5
Marievale Consolidated Mine
Kimberley Reef, Nigel Reef and Main
7L6
Marievale Consolidated Mine
Kimberley Reef, Nigel Reef and Main
7L7
Marievale Consolidated Mine
Kimberley Reef, Nigel Reef and Main
Grootvlei Complex
6L16
Grootvlei Proprietary Mines Limited
Kimberley Reef
6L17
Grootvlei Proprietary Mines Limited
Kimberley Reef
6L17A
Grootvlei Proprietary Mines Limited
Kimberley Reef
5A10/5L27 Sand Dumps
5A10/5L27
Modderfontein East Mine
Main Reef Leader
Daggafontein TSF
Daggafontein
Daggafontein Mine
Main Reef
Source: DRDGOLD, 2022
6.3
Stratigraphy and Cross-sections
Unlike the stratigraphy
of the in
situ mineral deposit,
the stratigraphy of
a TSF or
sand dump is
man-made.
A typical stratigraphy
is presented in
Figure 6.1. Slime
was deposited on
soil (original ground
level). The
color of topsoil ranges from red to black.
In some cases, soil is mineralized or enriched.
Technical Report Summary of the material Tailings Storage
Facilities
38
Figure 6.1:
A Typical Stratigraphy for Ergo’s TSFs
Source: The RVN Group, 2022
A typical cross-section of a TSF is shown in Figure 6.2 and
Figure 6.3.
Figure 6.2:
Grootvlei Complex (6L17) Map showing Location of
Cross-section
Technical Report Summary of the material Tailings Storage
Facilities
39
Source: The RVD Group, 2022
Figure 6.3:
Cross-section of the Grootvlei Complex (6L17)
Source: The RVN Group, 2022
6.4
Deposit Type
The
deposits
under
consideration
are
man-made
features
that
are
sometimes
referred
to
as
dumps,
tailing dams, or simply mine dams.
The
TSF
or
sand
dump
generally
lies
above
the
prevailing
ground
level
and
there
is
no
host
rock.
No
geological
or
mineralization
controls
are
relevant
to
the
TSFs
or
sand
dumps
as
they
are
man-made
features.
The engineering design
parameters determine the
size and shape of
the TSF or sand dump
at the time
of the deposition of the waste products from the respective
plants.
Technical Report Summary of the material Tailings Storage
Facilities
40
7
Exploration
7.1
Exploration
The TSFs are man-made engineering features and typical exploration programs (geophysics, trenching,
mapping
and
soil
sampling)
were
not
undertaken
on
the
TSFs.
An
evaluation
drilling
program
was
conducted on the
TSFs. No exploration
work was required
to locate the
TSFs,
as their locations
are well
known, rising well above ground level.
The QP considered non-drilling
exploration to be not material to
the Ergo properties.
7.2
Topographic Surveys
The
topographic
surfaces
of
the
TSFs
were
surveyed
by
Jaco
van
Staden,
a
qualified
surveyor
from
Geografix Surveys CC (Geografix), using a differential Global Positioning System (GPS) unit. The method
has an accuracy
in the range
of 10cm.
The conventional
survey equipment
(total stations,
prisms and
related
equipment)
and
GPS
Real
Time
Kinetic
systems
were
used
to
accurately
determine
the
coordinated positions of the surface features as required
to create a digital terrain model.
Daily calibration
through transformation
was completed
to ensure
the instruments
reported accurate
results. This standard procedure
was performed daily
before surveying. After
surveying was conducted
or when the day’s
work was completed,
the calibration was
rechecked through measurements
of the
benchmark
points
to
confirm
that
the
instruments
measured
the
correct
values.
Data
from
survey
measurements
were
checked
through
repeated
measurements
of
selected
points.
No
bias
was
identified.
Surveys
were
undertaken
on
a
10m
grid
and
measurements
were
also
taken
on
all
breaker
lines.
An
additional 10m to 20m outside the footprint of each
TSF and sand dump was also surveyed.
No additional tailings material was deposited on the TSFs after the surveys were
conducted. For the TSFs
where mining
is taking place
(4L50 and 5A10/5L27),
monthly surveys are
completed, and
the tonnage
is
depleted
from
the
Mineral
Resources
and
Mineral
Reserves
up
to
30
June
2022.
The
details
of
the
survey information are presented in Table 7.1.
The QP was satisfied to rely on the survey measurements as an accurate representation
of the TSFs and
sand dumps.
7.3
Evaluation Drilling
Evaluation
drilling
campaigns
were completed
on the
TSFs and
sand dumps.
The drilling
grid was
not
always regular due
to access issues;
however,
the QP noted
that drill holes
were well spread.
The well-
spread
drill
holes
ensured
that
the
samples
collected
were representative
of the
respective
TSFs
and
sand dumps.
7.4
Drilling Methodology
Two drilling
techniques were
followed by
specialized independent
drilling contractors
on the
TSFs. The
Reverse Circulation (RC) method was implemented where the
auger drilling technique could not drill to
Technical Report Summary of the material Tailings Storage
Facilities
41
the base of the TSF
due to drill hole length exceeding 55m or
areas of high moisture content
at the base
of the TSF.
The QP was satisfied that all measures
were taken to ensure that drilling,
sampling and recoveries were
acceptable and would not
affect the accuracy and
reliability of the
results. The experienced geologists
from The
RVN Group
monitored the
drilling process.
The QP
made ad-hoc
site visits
during drilling
and
sampling. In the
opinion of the
QP, the processes
followed were adequate for
collecting quality samples
and information for use in the interpretation of results and
in the Mineral Resource estimation.
Table 7.1:
Survey Details of the Material from the TSFs and Sand Dumps
TSF/Sand Dump
Area
(ha)*
Date Surveyed**
Coordinate System, Datum
Crown
3L5 (Diepkloof)
158.5
02/09/2013
WGS84 LO27, amsl***
3L7 (Mooifontein)
108.4
15/08/2013
WGS84 LO27, amsl
3L8 (GMTS)
159.3
20/09/2013
WGS84 LO27, amsl
City Deep
4L3
33.9
15/05/2017
WGS84 LO29, amsl
4L4
20.6
08/06/2017
WGS84 LO29, amsl
4L6
44.2
15/06/2017
WGS84 LO29, amsl
Knights
4L14
22.4
13/11/2015
WGS84 LO29, amsl
4L50
55.5
19/05/2017
WGS84 LO29, amsl
Ergo
Rooikraal
136.8
23/05/2018
WGS84 LO29, amsl
7L15
97.6
23/05/2008
WGS84 LO29, amsl
Marievale
7L4
116.3
19/01/2009
WGS84 LO29, amsl
7L5
31.1
08/01/2009
WGS84 LO29, amsl
7L6
62.0
20/01/2009
WGS84 LO29, amsl
7L7
69.1
22/01/2009
WGS84 LO29, amsl
Grootvlei
6L16
127.9
15/05/2015
WGS84 LO29, amsl
6L17
130.7
15/05/2015
WGS84 LO29, amsl
6L17A
85.7
15/05/2015
WGS84 LO29, amsl
5A10/5L27
5A10/5L27
56.7
26/02/2008
WGS84 LO29, amsl
Daggafontein
Daggafontein TSF
476.9
12/08/2016
WGS84 LO29, amsl
Total Area (Ha)
1,993.6
Source: The RVN Group, 2022
Note:
*area includes 10m outside the TSF footprint
**date before mining (4L50 TSF and 5A10/5L27 sand dump
are surveyed monthly for production purpose
s)
***amsl is the abbreviation for above mean sea level
Technical Report Summary of the material Tailings Storage
Facilities
42
7.4.1
Auger Drilling
Auger drilling,
a cost-effective
method, was
commissioned
by Ergo
on most
of their
TSFs for
holes less
than 55m and located within areas of lower moisture content
.
With auger drilling, the rotation of a helical screw causes the
blade of the screw to lift the sample to the
surface. This drilling method does not require heavy machinery in order to drill to the desired depth. This
auger method can
be used for
shallow environmental drilling, geotechnical
drilling, soil engineering
and
mineral deposits where the formation is soft and the hole does not collapse. This is done by pressing the
spiral rods into the ground using a drilling head machine
which can drill up to a depth of 55m.
Samples were collected through the spiral at every 1.5m interval and the spiral was cleaned with water
and brushed clean after every run.
7.4.2
Reverse Circulation
RC drilling,
with better sample
recovery than auger
drilling, is
a method of
drilling which
uses dual wall
drill rods consisting of
an outer drill rod
with an inner tube.
These hollow inner tubes allow
the drill cuttings
to be transported back to the surface in a continuous, steady
flow.
The drilling mechanism is often a pneumatic reciprocating piston called a hammer, which in turn drives
a clay cutter, specifically made to cut soft material
such as tailings and soil.
The clay cutter
is used to
remove samples that
are pushed through
the machine
with compressed air.
When
air
is
blown
down
the
annulus
(ring-shaped
structure)
of
the
rod,
the
pressure
shift
creates
a
reverse circulation,
bringing
the tailings
up the
inner tube.
When the
tailings reach
a deflector
box at
the top of the rig, the material is moved through a
hose attached to the top of the cyclone.
The drill cuttings will travel around the cyclone until they fall
through the bottom opening into a sample
bag. These bags are sorted and marked with the location and depth where the sample was collected.
RC drilling technique can drill up to 1,500m deep. The other benefits
of RC drilling include:
●
more reliable and less contaminated samples than
those from auger drilling;
●
a high drill penetration rate;
●
a larger sample size; and
●
a more cost-effective method than diamond or sonic
drilling.
Samples were collected through the cyclone at 1.5m
intervals and the rods and cyclone were cleaned
with compressed air after every run.
The RC drilling technique was chosen because RC drilling could drill deeper holes than auger drilling. In
addition,
because
of
its
higher
power,
RC
drilling
can
drill
through
wet
material
and
has
a
better
recovery percentage than auger drilling, which is prone to
losing wet samples through its spiral.
Technical Report Summary of the material Tailings Storage
Facilities
43
7.5
Crown
A total
of 44
RC drill
holes at
approximately
200m-by-200m
average grid
were completed
in 2017
on
Crown Complex as shown in Figure 7.1Figure 7.8.
Figure 7.1:
Crown Complex:
Map showing drill hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
44
7.6
City Deep
A total
of 27
auger drill
holes between
100m and
200m spacing
were completed
in 2017
on the
City
Deep Complex, as shown in Figure 7.2.
Figure 7.2:
City Deep Complex:
Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
45
7.7
Knights
7.7.1
4L14
A total
of 17
auger drill
holes were
completed on
4L14. The
average drill
hole spacing
was 100m.
Drill
holes are
well spread
throughout the
TSF as
presented
in Figure
7.3.The TSF
has a
maximum height
of
37.5m.
The
intersected
soil
reported
higher
gold
values;
thus,
the
soil
was
modelled
as
a
separate
domain and added to the TSF’s Mineral Resource.
Figure 7.3:
Knights Complex - 4L14: Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
46
7.7.2
4L50
A total of
22 auger drill
holes were completed
on 4L50. The
average drill hole
spacing is between
50m
and 100m. Drill
holes are
well spread throughout
the TSF (Figure
7.4). The
TSF has a
maximum height
of
40m. The average gold grade is 0.26g/t. Mining is ongoing
on this TSF.
Figure 7.4:
Knights Complex - 4L50: Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
47
7.8
Ergo
7.8.1
7L15
A total of 22 auger
drill holes were completed on 7L15. Some
holes were twin holes to confirm the
results
obtained in
previous drilling
campaigns.
The drill
hole pattern
has an
irregular spacing
averaging
less
than 100m (Figure 7.5).
Figure 7.5:
Ergo Complex - 7L15: Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
48
7.8.2
Rooikraal
A total of 64
RC drill holes were
completed on Rooikraal.
Irregular drill hole
spacing was due to
access
challenges (Figure 7.6). An average drill hole spacing
of less than 100m was achieved.
Figure 7.6:
Ergo Complex - Rooikraal: Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
49
7.9
Marievale
A drill
hole
map
for
the
Marievale
complex
is presented
in
Figure
7.7.
Average
spacing
of 100m
was
followed. Auger drilling was done in 2020.
Figure 7.7:
Marievale Complex:
Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
50
7.10
Grootvlei Complex
A total
of 34,
31 and
39 drill
holes were
completed on
6L16, 6L17
and 6L17A
respectively,
as shown
in
Figure 7.8,
Figure 7.9
and Figure
7.10. Drill
holes completed
in 2016
were a
combination of
auger and
RC
techniques.
All
previous
campaigns
(2008
and
2015)
used
the
auger
drilling
technique.
The
grid
spacing for 6L16 is
approximately 200m-by-200m
while 6L17 and
6L17A have a
closer drill hole
spacing
of approximately 100m-by-100m.
Figure 7.8:
Grootvlei Complex - 6L16: Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
51
Figure 7.9:
Grootvlei Complex - 6L17: Map showing Drill Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
52
Figure 7.10: Grootvlei Complex - 6L17A: Map showing Drill
Hole Locations
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
53
7.11
5A10/5L27
A total of 30 drill holes were completed on the 5A10/5L27 sand dumps
in 2017. All drill holes were drilled
using the auger
drilling technique.
An irregular spacing
of between 50m
and 100m
was followed.
Due
to the high
height of
the sand
dump, all
holes drilled
on top
of the
middle dump
did not
intersect the
base of the TSF (red color in Figure 7.11). Mining is ongoing
on this sand dump.
Figure 7.11:
5A10/5L27: Map showing Drill Hole Locations
Source: The RVN Group, 2022
The deepest
drilled hole
was 52.5m.
This drill
hole did
not intersect
the base
or soil.
The auger
drill machine
could not drill deeper
because the holes collapse
at depths,
due to auger drilling
constraints.
The RVN
Group geologists
stopped drilling
once they noticed
that the hole
had collapsed,
so as to
ensure that
only good-quality representative samples were obtain
ed.
Technical Report Summary of the material Tailings Storage
Facilities
54
7.12
Daggafontein TSF
A total of
55 drill holes
were drilled on
Daggafontein TSF from
2017 to 2021
as shown in
Figure 7.12. The
center of the TSF (outlined with a dotted line) could not be accessed for drilling
due to the presence of
surface water. Figure
7.12 presents the
evaluation drilling information for
the different drilling campaigns.
Only two drill holes were completed in 2017 which were drilled far apart. Drilling campaigns completed
from
2018
to
2021
were
drilled
to
infill
the
drill
space
to
confirm
the
continuity
of
mineralization.
On
average, the drill
holes were spaced
at a nominal
grid of 200m-by-200m
and were well
spread to ensure
that the samples were representative of the TSF.
Figure 7.12:
Daggafontein Complex - Daggafontein TSF: Map showing
Drill Hole Locations
Source: The RVN Group, 2022
7.13
Logging and Sampling
The RVN
Group used
comprehensive logging
and sampling
standard procedures,
including extensive
Quality
Assurance
(QA)and
Quality
Control
(QC)
procedures.
In
addition,
the
geologist
and
drilling
supervisor count
ed the
rods after
each hole
had intersected
the soil
to confirm
the borehole
depths.
Where samples were split, quartering was done by the
geologist on-site to ensure the representativity of
these samples.
The samples were assigned unique sample identification numbers and
tagged before being submitted
to the
laboratory. In
addition, for
each sample
batch, QC
samples were
submitted to
the laboratory.
Technical Report Summary of the material Tailings Storage
Facilities
55
The RVN Group geologists
prepared sample submission sheets that
accompanied the samples. Records
of the sample data were captured in a database.
The RVN Group monitored the
drilling and sampling process. Logging
was qualitative in nature, except
for sample intervals. All drill holes were logged in entirety
from top to bottom on-site.
As drilling progressed, the spiral for auger and rods for RC
drilling were cleaned after every drilling run to
prevent sample contamination.
7.13.1
Logging
Drill
holes
were
logged
on-site
by
The
RVN
Group
geologist
using
the
individual
1.5m
samples
taken
throughout the drill hole. Samples were classified according to whether they were slimes or soil, moist or
wet and on color.
Logging
was
done
on-site
as
hard
copy
handwritten
logs,
then
later
captured
electronically
into
Microsoft Excel.
7.13.2
Sampling
Every
drill
hole
was
sampled
at
1.5m
intervals
for
the
entire
length
of
the
hole.
The
samples
were
immediately
bagged
and
tagged
on
site. Sampling
(plastic)
bags
were labelled
and
tagged
with
a
sample book tag. The drill
log and sample book were
regularly checked against the
drill hole depth as
drilling proceeded so as to ensure compatibility.
Samples were noted as “dry”, “moist” or “wet”
in the drill log and sample book.
The
responsible
geologist
planned
sample
numbers
and
the
QC
samples
in
a
Microsoft
Excel
spreadsheet and assigned them to the appropriate
sample interval.
The RVN Group safely and carefully collected, secured and transported the samples
from the site so as
to avoid contamination and sample loss.
All
the
samples
were
presented
to
the
laboratory
in
a
well-organized
and
sorted
manner
with
easily
understandable documentation, including a fully
completed Sample Submission Form.
7.14
Sample Recovery
Samples
recovered
from
the
TSFs
and
sand
dump
material
were
mostly
moist
and
fine-grained.
The
sample size was visually checked on-site to ensure they were of
a similar size and sufficient quantity. The
gold grade did not show a definable relationship with sample weights.
The QP considered the recovery
and sample quality satisfactory for further evaluation.
7.15
On-site Security Measures
Access to the drill sites
was restricted to the drilling and
The RVN Group teams. Any
unauthorized access
to the drill
sites was prohibited.
Drilling sites were
demarcated by danger
tape and no
visitors could cross
the demarcated area unless
authorized by the QP.
Once samples were packed
and the bags closed,
no one was allowed to open the bags.
Technical Report Summary of the material Tailings Storage
Facilities
56
7.16
Collar Survey Data
A qualified
surveyor from
Geografix surveyed
the drill
hole collar
positions using
total station
surveying
equipment and differential GPS instruments. The accuracy
of the method was within a 10cm range.
Collar positions were plotted on the satellite images to verify positions and collars plots were inspected.
Elevations were compared to the topographic survey.
Collar positions were verified to be accurate.
The QP is satisfied with the surveying methodology followed. The surveys were performed by a qualified
surveyor
who
has
sufficient
experience
to
undertake
the
task.
The
surveys
were
considered
to
be
of
adequate quality for use in the evaluations of the TSFs.
No downhole survey measurements were taken as the drill holes were shallow and vertical,
and the QP
anticipated no deviations.
7.17
Density Determination
Bulk densities on the TSFs were measured in situ by Letsatsi Materials Engineering (Proprietary) Limited (a
South
African
National
Accreditation
System
(SANAS)
accredited
institution
for
engineering
materials
testing)
using
a
Troxler
densitometer
between
September
2020
and
January
2021.
The
bulk
density
measurements
included compaction rates and moisture content. The use of densitometers on TSFs and
sand
dumps
is
common
practice,
as
TSFs
and
sand
dumps
are
engineered
features
with
consistent
physical properties.
The density
of the TSF
is directly
proportional to
the compaction
rate and material
property. As
the moisture
content increases,
density
decreases and
vice
versa. The
compaction
rate
and
material
property
do
not
vary
significantly
with
depth
(TSFs
and
sand
dumps
are
largely
homogeneous);
thus,
measurements
taken
at
any
depth
(>10cm)
are
representative
of
the
TSF
and
sand dump compartments.
Density measurement points were prepared and measurements
were taken per TSF or sand dump. The
points
were
well
spread.
Preparation
of points
involved
removing
the
topmost
5cm
to
10cm
of loose
material and flattening (levelling) the
surface. Measurements were taken at
150mm and 300mm depths
per point. As part of quality control, some points are measured
more than once.
The statistics of the density measurements are presented
in Table 7.2.
The average bulk densities determined
for the TSFs or sand dump were
slightly higher than the
1.42t/m
3
that Ergo uses for the TSFs or sand dump they are mining.
The mean tests showed that the density is more than 1.42t/m
3
with a 95% confidence level. Confidence
intervals for the densities indicated,
with a 95% confidence level, that the mean density applied at Ergo
is within the range. The QP decided to
continue using a lower mean density of 1.42t/m
3
as it is within the
95% confidence and prediction intervals, passed the mean test. In addition,
Ergo has been successfully
applying 1.42t/m
3
in their mining production reconciliation for more than
15 years.
The
QP
is
satisfied
using
a
1.42t/m
3
mean
dry
bulk
density
for
all
the
TSFs
and
sand
dumps
with
the
understanding of the upside potential if the mean
density is later determined to be higher.
Technical Report Summary of the material Tailings Storage
Facilities
57
Table 7.2:
Bulk Density Information and Statistics
Reclamation Site
TSF/Sand Dump
Number
of
Samples
Mean Density
(t/m
3
)
Standard Deviation
(t/m
3
)
Minimum
(t/m
3
)
Maximum
(t/m
3
)
CoV***
Crown Complex
3L5
60
1.479
0.044
1.353
1.567
0.03
3L7
60
1.443
0.020
1.381
1.485
0.01
3L8
32
1.397
0.028
1.331
1.440
0.02
City Deep Complex
4L3
20
1.419
0.078
1.214
1.560
0.05
4L4
20
1.456
0.031
1.410
1.522
0.02
4L6*
-
-
-
-
-
-
Knights Complex
4L14*
-
-
-
-
-
-
4L50
30
1.624
0.040
1.531
1.711
0.02
Ergo Complex
7L15
30
1.513
0.035
1.443
1.591
0.02
Rooikraal
90
1.457
0.051
1.350
1.602
0.04
Marievale Complex
7L4
60
1.457
0.033
1.405
1.526
0.02
7L5
30
1.434
0.047
1.360
1.520
0.03
7L6
60
1.453
0.060
1.335
1.595
0.04
7L7
60
1.461
0.032
1.374
1.548
0.02
Grootvlei Complex
6L16
60
1.543
0.060
1.384
1.643
0.04
6L17
59
1.499
0.038
1.420
1.592
0.03
6L17A
58
1.490
0.044
1.402
1.606
0.03
5A10/5L27 Sand
Dumps
5A10/5L27
30
1.529
0.037
1.468
1.596
0.02
Daggafontein TSF
Daggafontein
58
1.511
0.058
1.394
1.687
0.04
Total
817
1.480**
0.043
1.214
1.711
0.03
Source: The RVN Group, 2022
*no measurements were taken due to access
problems
**weighted average
***CoV is the abbreviation for Coefficient of Variation
Technical Report Summary of the material Tailings Storage
Facilities
58
7.18
Hydrological Drilling and Test Work
No hydrogeological studies were completed.
However, some relevant hydrological data
was captured during
drilling and logging by
The RVN Group.
The RVN Group logs have moisture
content recorded (i.e., dry,
moist, wet or watery). Additionally, Ergo
installed
piezometers
in
some
larger
TSFs
(Crown
Complex
and
Daggafontein
TSF)
to
monitor
water
levels.
Smaller
TSFs
are
considered
low
risks
as
they
are
dormant
and
mostly
moist
to
dry;
thus,
no
piezometers were installed.
7.18.1
Crown Complex
The QP has classified the GMTS TSF as moist
to wet and Diepkloof and Mooifontein TSFs
are classified as
dry to moist (Table 7.3, Table 7.4 and Table 7.5).
Table 7.3:
GMTS (3L8) Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
27.0
Dry
27.0
54.0
Moist
54.0
58.5
Wet
58.5
61.5
Watery
61.5
64.5
Wet
64.5
67.5
Watery
67.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.4:
Diepkloof (3L5) Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
21.0
Dry
21.0
45.0
Moist
45.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.5:
Mooifontein (3L7) Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
30.5
Dry
30.5
36.0
Moist
36.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
59
7.18.2
City Deep Complex
The QP classified the City Deep Complex as moist (Table
7.6, Table 7.7 and Table 7.8).
Table 7.6:
4L3 Moisture Content
Average Depth
Moisture Content Commentary
From (m)
To (m)
0.0
31.5
Moist
31.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.7:
4L4 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
The Base of the TSF
Moist
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.8:
4L6 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
13.5
Moist
13.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
7.18.3
Knights Complex
The QP classified the Knights TSFs as moist (Table
7.9 and Table 7.10).
Table 7.9:
4L14 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
4.5
Dry
4.5
12.0
Moist
12.0
25.0
Wet
25.0
30.0
Moist
30.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
60
Table 7.10:
4L50 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
16.5
Moist
16.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
7.18.4
Ergo Complex
The
QP
classified
the
Rooikraal
TSF
as
moist
to
wet
(Table
7.11
to
Table
7.12).
The
TSF
is
moist
to
wet
because it is situated closer to the wetland. The 7L15 TSF is
moist.
Table 7.11:
Rooikraal Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
12.0
Moist
12.0
13.5
Dry
13.5
22.5
Wet
22.5
The Base of the TSF
Watery
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.12:
7L15 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
19.5
Moist
19.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
7.18.5
Marievale Complex
The QP classified
the Marievale
TSFs as moist
to wet (Table
7.13, Table 7.14,
Table 7.15 and
Table 7.16).
The
TSF
is
moist
to
wet
because
it
is
situated
closer
to
the
Blesbokspruit.
All
TSFs
are
east
of
the
Blesbokspruit.
Table 7.13:
7L4: Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
6.0
Moist
6.0
10.5
Wet
10.5
The Base of the TSF
Watery
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
61
Table 7.14:
7L5: Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
1.5
Dry
1.5
12.0
Moist
12.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.15:
7L6: Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
4.5
Dry
4.5
15.0
Moist
15.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.16:
7L7: Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
6.0
Dry
6.0
10.5
Moist
10.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
7.18.6
Grootvlei Complex
The
QP
classified
the
Grootvlei
TSFs
as
wet
(Table
7.17,
Table
7.18
and
Table
7.19).
The
TSFs
are
wet
because they are situated closer to the Blesbokspruit wetland area. The
6L17 and 6L17A TSFs are east of
the Blesbokspruit,
while the 6L16 TSF is located to the west.
Table 7.17:
6L16 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
7.5
Moist
7.5
24.5
Wet
24.5
The Base of the TSF
Watery
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
62
Table 7.18:
6L17 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
4.5
Dry
4.5
18.0
Moist
18.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Table 7.19:
6L17A Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
13.5
Dry
13.5
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
7.18.7
5A10/5L27
The QP classified
the 5A10/5L27 sand dumps
as moist to
dry sand dumps. This
is because courser
grained
sand does not trap water like the finer grained tailings
slime (Table 7.20).
Table 7.20:
5A10/5L27 Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
The Base of the TSF
Moist
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
7.18.8
Daggafontein TSF
Daggafontein TSF
has water
on the
surface.
The QP
classified
it as
wet. It
was estimated
that at
least
one million cubic meters of water are on top of Daggafontein
TSF (Table 7.21).
Table 7.21:
Daggafontein Moisture Content
Average Depth
Moisture Content Commentary
From
(m)
To
(m)
0.0
12.0
Dry
12.0
16.0
Moist
16.0
19.5
Wet
19.5
30.0
Watery
30.0
The Base of the TSF
Wet
The Base of the TSF
Soil
Moist
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
63
7.19
Geotechnical Data, Testing and Analysis
No geotechnical testing and sampling were completed
on the TSFs and sand dumps.
However,
stability
assessment
studies
were
completed
on
the
TSFs
with
a
greater
than
60Mt
Mineral
Resource. In 2019, stability assessments were conducted on
Daggafontein TSF and Crown Complex TSFs
by Lutails Engineering (Proprietary) Limited. No studies
were completed on other the TSFs
or sand dumps
as they are small, dormant)
and pose a low geotechnical stability risk.
The following were observed on the Daggafontein
TSF:
●
there was no seepage anywhere around the toe of the
TSF;
●
some of the catchment paddocks,
where they still exist, are quite silted and should be cleaned
or re-shaped during a rehabilitation process;
●
the filter drains were mostly open but in need of jet-rodding
to remove sedimentation;
and
●
there was water visible on the top surface.
On the Crown Complex TSFs, the following conclusions
were made:
●
there
are
adequate
controls
on
the
TSFs
to
prevent
stormwater
damage,
with
no
significant
spillages having occurred over the past few years;
●
the potential
for wind-blown
dust has been
ameliorated through
ridge ploughing
of the basins
and due to the presence of well-established vegetation;
●
vegetation has been established on most side slopes thereby reducing water and wind erosion.
There have been
no reports
of significant
spillages from the
Crown Complex
over the past
few
years;
●
most of
the filter
drain
outlets
are no
longer
operational,
and recorded
drain
flow is
therefore
only a fraction
of what it
was. Despite the
outlet pipe losses,
the is very
little evidence of
seepage
from the toe of the TSF; and
●
most of the
standpipe piezometers
are no
longer operational.
Those remaining
show a drop
in
piezometric levels,
albeit it less than reasonably expected.
Hydrogeological
advice
is
obtained
prior
to
mining
activities
as
the
combination
of
high
moisture
content and fine particles could, during mining activities, result in liquefaction and mud
rush conditions.
A risk
assessment is undertaken
when commencing mining
of a
TSFs or
sand dump to
avoid slope failures.
Ergo and their mining contractors have procedures to ensure safe mining and loading of TSFs and sand
dumps which can be as high as 70m.
Ergo had not reported any
significant slope failures associated
with the retreatment operations
of their
TSFs or sand dumps in the past 15 years.
The QP
is satisfied
that the
stability studies
of the
TSFs are
sufficient and
meet the
requirements for
the
intended purpose.
Technical Report Summary of the material Tailings Storage
Facilities
64
8
Sample Preparation, Analyses and Security
8.1
Sampling Governance and Quality Assurance
The RVN
Group
used its
standard
procedures
for
data
collection,
analysis,
validation
and
storage.
In
addition, regular
planned task
observations of
procedures and
their implementations
are undertaken
to
ensure
compliance
and
appropriateness
for
the
drilling
program.
Training
and
planned
task
observations are provided by the QP.
The sample chain of custody is managed by experienced
geologists from The RVN Group.
The QP is satisfied with the QA and QC protocols in
place.
8.2
Sample Preparation and Analysis
8.2.1
On-site Sample Preparation
All samples were
halved on-site by a
geologist through the cone
and quartering method as
the samples
were too
moist or
wet to
use a
riffle splitter,
which has
the potential
to introduce
cross-contamination
and bias. The cone and
quartering method does
not introduce a systematic
bias as it involves pouring
each sample on a clean, flattened bag (1.0m-by-0.5m).
The quartering method is considered appropriate for the TSF material as TSF samples are homogeneous
due
to
the
deposition
procedure.
Figure
8.1
shows
the
cone
and
quartering
methodology
followed.
One half is for the metallurgical test and the other half
is for a routine exploration sample.
Figure 8.1:
Cone and Quartering Method
Source: Modified after Alakangas, 2015
Technical Report Summary of the material Tailings Storage
Facilities
65
Sorting of samples took place on the TSFs and at the
storage site at Ergo.
Where
a
field
duplicate
was
required,
a
selected
routine
exploration
sample
underwent
a
further
quartering process.
To maintain
validity and
integrity of
samples and
as part
of security
measures,
only geologists
worked
on the samples,
and samples were sealed immediately after preparation.
8.2.2
Laboratories, Sample Preparation and Analyses
The samples
were sent
to the
following three
reputable laboratories for
further preparation and
assaying:
●
MAED at
Ergo’s Plant
in
Brakpan:
The facility
is not
accredited
but it
is the
laboratory
used by
Ergo
for
its
grade
control
and
daily
plant
samples.
MAED
is
not
owned
by
Ergo,
although
it
is
situated in the Ergo Plant and was supplied with all routine
exploration samples for analysis;
●
SGS
in
Randfontein:
SGS
is
a
SANAS
accredited
facility
(T0265)
and
has
been
used
for
the
selected analytical method. Randomly selected check samples
(approximately 10% of the total
samples)
from MAED were sent to SGS for confirmation. SGS is independent
of Ergo;
and
●
AngloGold
Ashanti
Limited
Chemical
Laboratory
(Anglo
Lab)
in
Carletonville:
Anglo
Lab
analyzed some check samples
for 7L15 TSF
in 2016 and 2017
as a secondary laboratory
to MAED.
The
laboratory
no
longer
exists
and
it
was
not
SANAS
accredited.
The
laboratory
was
independent of Ergo.
Technical Report Summary of the material Tailings Storage
Facilities
66
Table 8.1 presents information about where the samples
were analyzed.
Table 8.1:
Laboratories Used
TSF/Sand Dump
Primary Laboratory
Secondary Laboratory
Crown Complex
3L5
MAED
3L7
MAED
3L8
MAED
City Deep Complex
4L3
MAED
SGS
4L5
MAED
4L6
MAED
Knights Complex
4L14
MAED
SGS
4L50
MAED
SGS
Ergo Complex
Rooikraal
MAED
SGS
7L15
MAED
SGS and Anglo Lab
Marievale Complex
7L4
MAED
7L5
MAED
7L6
MAED
7L7
MAED
Grootvlei Complex
6L16
MAED
SGS
6L17
MAED
SGS
6L17A
MAED
SGS
5A10/5L27 Sand Dump
5A10/5L27
MAED
Daggafontein Complex
Daggafontein
MAED
SGS
Source: The RVN Group, 2022
The laboratories sorted and weighed samples
on receipts, conducted dry screening to remove
foreign
material.
Subsequently,
the samples
were dried
at 105
˚
C, then
crushed to
80% passing
2mm, riffle
split
and finally pulverized to 75µm before being analyzed.
The selected laboratories follow analytical procedures
that are conventional industry practice.
The samples were
analyzed for gold
by fire
assay with gravimetric
finish by MAED
and Atomic Absorption
Spectroscopy (AAS) finish
by SGS and
Anglo Lab. These
methods are conventional and
have been used
for more than 50 years
with minor adjustments.
The methods have a
lower detection limit
of 0.01g/t Au
and there is no upper detection limit for gravimetric finish.
The AAS has a 10g/t Au upper limit. The lower
limit is relevant to the TSFs and sand dumps.
The TSFs and sand dumps are processed materials
and are
generally low-grade materials
with slightly higher grades than ten times the detection limit.
The
laboratories
were
instructed
to
use
a
100g
aliquot
to
analyze
for
gold.
Through
experience,
it
is
known that
to analyze
for gold
in low-grade
slimes, anything
less than
a 100g
aliquot may
report less
accurate results.
Technical Report Summary of the material Tailings Storage
Facilities
67
8.2.3
QP Opinion
The
QP
is
satisfied
with
the
sample
preparation,
analytical
methods
and
level
of
cleanliness
at
the
analytical laboratories.
The analytical
techniques employed
are suited
to the
mineralization style
and
expected grades. The techniques meet the requirements for
the intended use.
8.3
Analytical Quality Control
8.3.1
Nature and Extent of the Quality Control Procedures
A comprehensive
QC program
comprising
reference material,
duplicates and
commercially
sourced
certified
blanks
were
inserted
by
The
RVN
Group
in
a
random
but
stratified
manner,
at
frequencies
targeting
±
10% coverage
of all samples.
The QC
program identifies
various aspects
of the results
that
could negatively influence the subsequent
evaluation processes. The QC
samples were used to
monitor
the sampling, sample preparation and analytical processes. Analysis of QC data
is performed to assess
the
reliability
of
all
sample
assay
data
and
the
confidence
in
the
data
used
for
Mineral
Resource
estimation.
All QC sample insertions maintained consecutive numerical
order. These control samples were inserted
as part
of a
continuous
sample
number
sequence
and
the
QC samples
were not
obviously
different
from routine samples when
the milled material was
prepared and analyzed.
Applying the QC process,
it
was
possible
to
identify
samples
that
have
been
swapped,
gone
missing
or
incorrectly
labelled
amongst other aspects.
QC
samples
were
sourced
from
African
Mineral
Standards
(AMIS)
based
in
Modderfontein,
Johannesburg.
The
RVN
Group
ensured
that
all
standards
and
blanks
were
stored
in
sealed
containers
and
considerable care
was taken to
ensure that they
were not contaminated
in any manner
(i.e., through
storage in a dusty environment or being placed in
a contaminated sample bag, etc.).
Field duplicates were prepared on-site as the TSF
material was already loose and fine-grained.
The QC set of samples consisted of:
●
the certified silica blanks (AMIS0484) from AMIS;
●
certified
reference
materials
(CRMs)
(AMIS0647
with
0.17g/t
Au,
AMIS0299
with
0.36g/t
Au,
AMIS0515 with 0.51g/t Au) from AMIS;
●
standard
reference
material
L-AU015
and
L-AU16
with
an
average
value
of
0.20g/t
Au
and
0.30g/t Au, respectively
.
Standard reference
materials
with the averages
of 0.22g/t Au,
0.33g/t
Au and 0.74g/t Au were also used; and
●
field duplicates (prepared through the cone and quartering
technique discussed in Item 8.2.1).
From 2021, only CRM
were used and the
use of inhouse standard
reference material was discontinued
as inhouse
standards
performance
was not
always
consistent.
The
QP noted
that
this
does not
imply
that the previous results
were of low quality
as rigorous quality
control assessments were
implemented.
Technical Report Summary of the material Tailings Storage
Facilities
68
The new
procedure
of
using
only
CRM
with
a matched
matrix
was
implemented
because
the
CRMs
come with defined certified values and are easier to monitor.
8.3.2
Quality Control Results
Analytical results for the
blank and standards are analyzed graphically on
control charts to facilitate
the
identification of
anomalous data
points. A
sufficient number
of standards
and blanks
are inserted into
the sample stream. If the standard result is reported outside three standard deviations
of the certificate
value
–
a re-assay would be requested for the whole batch from
the laboratory.
8.3.3
QP Opinion
In the QP’s opinion, the QC samples covered
a reasonable range of grades with respect
to the overall
resource grades
and no
significant bias
was observed.
The laboratories’
analytical data
shows overall
acceptable
precision
and
accuracy
and
no
evidence
of
overwhelming
contamination
by
the
laboratory
that
would
affect
the
integrity
of
the
data.
As
a
result,
the
analytical
data
from
the
laboratories is of acceptable integrity and
can be relied upon
for TSF and sand dump
grade estimation.
8.4
Sample Storage and Security
Samples were
stored at
the Archive
Store at
Ergo’s processing
plant in
Brakpan. The
storage facility
is
always locked and
has an electric
fence to prevent
unauthorized entry. Sample
rejects and pulps
are
stored for six months after all assays are received from the laboratory
and then discarded.
8.5
Data Storage and Database Management
Procedures are in place to ensure the accuracy and security
of the databases.
Laboratories reported results in
Microsoft Excel and .pdf
formats.
The RVN Group
copied and pasted the
results into the database. Spot checks were
randomly performed to identify copying and pasting errors.
The RVN Group created and validated the database on behalf
of Ergo. The database was developed
and validated in Microsoft Excel. The database was sent to
Ergo for further use and storage.
The RVN Group compiled the following key digital
databases:
●
a drill hole database that includes collar location, assay
and geology data;
●
assay quality control data;
●
density data; and
●
process samples information.
The QP is satisfied with
data storage and validation
.
Database management practices
adhere to best
practice. The QP is of the opinion that the databases are a fair and accurate
record of all drill hole and
assay data.
Technical Report Summary of the material Tailings Storage
Facilities
69
The RVN
Group has
saved the
information, including
the databases,
in the
cloud as
a backup,
in line
with the latest technological developments. Additionally,
data is stored on external hard drives placed
in
different
locations.
The
RVN
Group
has
provided
sufficient
provisions
to
ensure
the
security
and
integrity of the data stored in the databases.
Technical Report Summary of the material Tailings Storage
Facilities
70
9
Data Verification
Post-2016:
The QP performed
verifications of the
data collected.
The QP experienced
no limitations
to
the review, analysis and verification of data.
The QP
did compare
a selection
of the
hardcopy logs
with the
drill holes
database and
the logs
and
database match. The
collars were checked by
comparing the collars with
the topography surface from
the surveyor. Collars were also plotted on Google Earth Pro for confirmation. The collars were
accurate.
Logging, surveying
and sampling
were monitored
by the
exploration geologists
and verified
routinely
for
consistency.
The
RVN
Group
geologists
regularly
maintain
and
validate
the
databases
using
validation
routines
and
regularly
check
the
drill
hole
data
visually
on-screen.
A
first
check
consists
of
identifying duplicate sample numbers or lack of
sample information. Paper records are stored in
a safe
location at Ergo’s Offices.
The QP
is of
the opinion
that the
data collection,
import and
validation workflows
are consistent
with
industry standards and are of sufficient quality to support
the Mineral Resource estimation.
The QP has
taken a number of
steps to verify
the Mineral Resource estimates,
including assumptions and
inputs
into
the
estimate
and
the
estimation
process
itself.
The
QP
checked
the
volume,
density
and
grade
with
the
Mineral
Resource
QP
along
with
the
mine
planning
specialist,
noting
that
based
on
historical information, no dilution or mining loss is applied
to the Mineral Resource.
The
QP
conducts
quarterly
reconciliations
of
Run-of-Mine
(RoM)
grade,
tonnage,
recovery
(metallurgical
assumptions)
and
other
modifying
factors
from
the
ongoing
mining
operations
to
demonstrate that
the modifying
factors applied
to the
mine plan
are as
predicted by
the geological
block model.
Actual
performance
for
operational
mining
areas
provides
a
high
level
of
confidence
where
similar
performance
can
be
expected
from
future
mining
areas.
The
current
Mineral
Reserves
have
not
demonstrated any
material differences
in the
planned and
actual modifying
factors. The
QP is
of the
opinion that the data used to estimate the Mineral
Reserve is adequate.
Historical:
Sampling and assaying of the TSFs and sand dumps
prior to 2016 is essentially the same as
the
current work. The only real change noted by the
QP is that the sieve size was
reduced to 850µm in 2016,
where it
was 1,000µm
previously.
Currently,
there is
no apparent
difference between
the results
using
these different sieve sizes.
The analytical
method is fire
assay, a well-established
technique used in
the South African
gold mines.
The methods differed slightly over time and between laboratories, but the results are consistent within a
TSF. Aliquot sizes have been either 100g or 125g, depending
on the laboratory used.
Quality control systems are in place in laboratories
to monitor accuracy and precision.
Technical Report Summary of the material Tailings Storage
Facilities
71
10
Mineral Processing and Metallurgical Testing
10.1
Nature and Extent of the Metallurgical Testing Method
Samples were
received from
the
various drilling
exercises in
1.5m increments
for each
hole.
Typically,
composites were made
over a 15m
horizon as
this corresponds
with the monitoring/mining
depth. The
TSFs and sand dumps were generally divided into a top, middle and bottom horizon, depending on the
height of the TSF or
sand dump. In the plans, the TSFs
were also divided into areas giving distinct domain
samples for metallurgical test work.
10.2
Procedure
10.2.1
Slime Material
The individual
samples were split
in two using
a blending
mat, and cone
and quartering methods.
The
one half
was returned
to the
sample bag
for possible
future use
and for
reference. The
other half
was
composited as per the areas/horizons or
domain alluded to earlier. The composite
was well mixed and
sub-samples
taken
for
test
work
at
Ergo
Metallurgical
Research
or
at
the
Maelgwyn
South
Africa
(Proprietary) Limited’s laboratory.
The proposed
processing
route for
all TSF
and sand
dump material
is hydraulic
mining, cyaniding
in a
Carbon-in-Leach (CIL) circuit, with
the tailings deposited onto
another TSF, and then
carbon eluted for
gold recovery before being recycled back to the
leach.
A standard bottle roll test was done on each composite
using the following leaching parameters:
●
samples slurried to a density of 1.45;
●
screened to remove +850µm discard material;
●
head sample was taken for triplicate fire assay;
●
pre-conditioning with lime for one hour to stable pH of 10.5;
●
cyanide added at 0.35kg/t;
●
activated carbon added at 20g/l;
●
leach terminated after seven hours;
●
solids filtered and washed twice and solutions tested for residual
reagents and gold content;
●
residue assays done in triplicate.
10.2.2
Sand Material
Metallurgical test work
was conducted on
5A10/5L27 sand dump
drilling samples. The
objective of the
test
work
was
to
validate
the
gold
grades
received
from
the
Mineral
Resource
Management
(MRM)
Department,
assess
the
milling
requirements
and
evaluate
the
leach
kinetics/characteristics
of
the
material. The dump was partitioned into four sections. The average gold grade received from the MRM
Department for
Section 1
was 0.62g/t,
Section 2
was 0.30g/t,
Section 3
was 0.51g/t
and Section
4 was
Technical Report Summary of the material Tailings Storage
Facilities
72
0.41g/t.
The
average
gold
grade
obtained
from
metallurgical
research
test
work
for
Section
1
was
0.62g/t, Section 2 was 0.30g/t, Section 3 was 0.51g/t
and Section 4 was 0.39g/t.
The samples
were milled
over varying
durations and
milling curves
plotted to
determine the
optimum
milling time. The milling curves
indicate that the optimum
milling duration achieving
at least 60% -75µm
is 2.5 hours
for Section
1 and
2 hours
for Sections
2, 3 and
4. Leach
tests were
then conducted
on the
milled product and the results confirm that gold yield increases
with increased milling time.
The respective 5A10 material responds well to cyanide leach as desired dissolution of 60% was attained
for all Sections at the above milling durations. Preg-robbing tests were also
conducted on material from
Sections 1 and 3 and the results indicate that there
is no significant preg-robbing.
10.3
Representative of the Samples
Drill holes were drilled on a defined grid down to the soil. The samples
received were correctly split and
composited,
and are considered to be representative of the various volumes
within the TSFs.
10.4
Details of the Laboratories
The
Ergo
Metallurgical
Research
Laboratory,
located
in
Brakpan
inside
the
Ergo
processing
plant,
is
geared
to
perform
bottle
roll
testing
on
a
routine
basis
with
skilled
technicians.
Internal
accounting
checks are undertaken to ensure the accuracy of the work done. The laboratory is not accredited and
is the internal test facility for Ergo. The laboratory is
not independent of Ergo.
The
Maelgwyn
South
Africa
(Proprietary)
Limited
(Maelgwyn)
laboratory,
situated
in
Roodepoort,
is
accredited for International
Organization for Standardization
(ISO 9001:2025)
to perform gold leaching
test work
with their
assays analysis
conducted by
the SGS laboratory
,
in Randfontein.
SGS is
an SANAS
accredited facility (T0265) for gold analysis.
Both the Maelgwyn and SGS laboratories are independent
of Ergo.
10.5
Results
The main assumption was that the laboratory procedure emulates
the processing plant and historically
this has
been shown
to be
a fair
assumption. To
accommodate the
dissolved loss
encountered in
the
processing plant,
an allowance of 0.008g/t
Au is made to
calculate the predicted recovery in
the plant.
Technical Report Summary of the material Tailings Storage
Facilities
73
Table 10.1 presents the results of metallurgical test
work.
Table 10.1:
Summary of Predicted Ergo Processing Plant Performance
TSF/Sand Dump
Head Au
(g/t)
Washed
Residue Au
(g/t)
Dissolution
Loss Au
(g/t)
Recovery
(%)
Analysis Laboratory
Crown Complex
3L8 (GMTS)
0.25
0.14
0.008
41
Ergo
3L7 (Mooifontein)
0.23
0.13
0.008
40
Ergo
3L5 (Diepkloof )
0.23
0.14
0.008
36
Ergo
City Deep Complex
4L3
0.32
0.12
0.008
60
Ergo
4L4
0.37
0.21
0.008
41
Ergo
4L6
0.31
0.12
0.008
58
Ergo
Knights Complex
4L14
0.28
0.15
0.008
44
Maelgwyn/Ergo
Ergo Complex
4L50
0.26
0.16
0.008
35
Maelgwyn/Ergo
Rooikraal
0.25
0.17
0.008
31
Ergo
7L15
0.28
0.14
0.008
47
Maelgwyn/Ergo
Marievale Complex
7L4
0.29
0.13
0.008
52
Ergo
7L5
0.30
0.19
0.008
34
Ergo
7L6
0.24
0.16
0.008
30
Ergo
7L7
0.34
0.2
0.008
39
Ergo
Grootvlei Complex
6L16
0.25
0.17
0.008
33
Maelgwyn/Ergo
6L17
0.26
0.13
0.008
47
Maelgwyn/Ergo
6L17A
0.26
0.15
0.008
39
Maelgwyn/Ergo
5A10/5L27 Sand Dumps
5A10/5L27
0.49
0.21
0.008
60
Ergo
Daggafontein TSF
Daggafontein
0.25
0.16
0.008
35
Ergo
Source: DRDGOLD, 2022
10.6
Interpretation of the Results
Table
10.1
summarizes
the
metallurgical
test
work
that
has
been
done
on
the
various
TSFs
and
sand
dumps. In
the table
under the
‘comments’
column,
an indication
as to
which laboratories
carried out
the test work
is given. The
head grade and
washed residue
are the results
achieved in
the laboratory.
In order
to predict
how the
material would
respond to
treatment in
the Ergo
processing plant,
a dissolved
gold loss
of 0.008g/t
Au has
been applied.
In general,
the head
grades vary
between 0.25g/t
Au and
0.32g/t Au. The response to cyanidation is varied
which could be due to numerous factors.
Technical Report Summary of the material Tailings Storage
Facilities
74
10.7
QP Opinion
In the opinion of
the QP, data derived
from metallurgical test work is
adequate for designing processing
facilities and techniques,
and provides suitable
grade and recovery predictions
for use in
the LoM plans.
Confidence is further increased by processing plant performance demonstrated through reconciliation
for over ten years.
The metallurgical process is well tested and utilized by numerous tailings
retreatment operators in South
Africa and elsewhere. There were no processing factors
or deleterious elements that could significantly
affect potential economic extraction.
Technical Report Summary of the material Tailings Storage
Facilities
75
11
Mineral Resource Estimates
The gold grade estimation was completed using two
modelling techniques: Inverse Distance Weighting
(IDW)
to
the
power
of
2
and
validation
using
the
Nearest
Neighbor
(NN)
technique.
The
techniques
reported a similar average global gold grade with no significant conditional bias.
The Mineral Resource
estimation
was
declared
using
the
IDW
to
the
power
of 2.
The estimation
approach
was
considered
appropriate
based
on the
review
of
several
factors,
including
the
quantity
and
spacing
of available
data, the interpreted
control on miner
alization,
the style and
geometry of the
mineralization as well
as
geological logging
and additional
information recorded
from the drill
holes. TSFs
and sand
dumps are
man-made engineering features which was considered
in the estimation process. Ordinary Kriging was
considered
unnecessary
for
TSF
and
sand
dump
evaluation
as
the
main
aim
was
to
obtain
global
averages rather than local variations considering
the envisaged or applied mining method.
Mineral Resources were
estimated for all
the TSFs, and
the estimation procedures
are similar in
approach
for all the
TSFs and sand
dumps. However,
each TSF and
sand dump is
treated as a
separate entity
as
each has differences due to data distribution and characteristic of the material. Estimation procedures
and parameters are given individually per TSF or sand
dump.
All tailings material
is above the
current land surface
and continuity of
grade within
the TSFs is
defined
based on +/-100m
drill hole spacing.
The tailings material
has been processed
through a metallurgical
treatment plant
that ejects
a waste
residue that
is relatively
uniform when
compared with
the natural
deposit from which the material
is derived. The variation between
samples and drill hole is
small (0.1g/t
to 1.0g/t) in comparison
to in situ gold
deposits. However, the
percentage difference may
be huge as
is the case with trace elements.
Datamine’s
Studio
RM
geological
modelling
software
was
used
as
the
modelling
tool.
Most
of
the
statistical and geostatistical
study was completed
using SAS JMP
Pro and the
RStudio, an open-source
integrated
development
environment
for
“R”,
a
programing
language
for
advanced
statistical
computing and graphics.
Mineral Resource
estimates are not
Mineral Reserves and
do not
have demonstrated
economic viability.
There is no
certainty that all or
any part of
the Mineral Resource will
be converted into
a Mineral Reserve.
The Mineral Resource estimates for all the TSFs and
a sand dump are declared as follows:
●
the point of reference is
in situ
. The TSFs or sand dumps themselves are the reference
points;
●
no
geological
or
other
losses
were
applied
as
all
material
is
accessible
and
there
are
no
geological structures;
●
Mineral
Resource
estimates
are
stated
as
both
inclusive
and
exclusive
of
Mineral
Reserves
as
defined in Subpart 1300 of Regulation S-K; and
●
the Mineral Resource is 100% attributable to Ergo. DRDGOLD,
the registrant, owns 100% of Ergo.
Item 11.1 to Item
11.7 present the methodology followed
a similar methodology for all the
TSFs and sand
dumps. Item 11.9 to Item 11.16 provides detail for
each complex,
TSF or sand dump.
Technical Report Summary of the material Tailings Storage
Facilities
76
The 79 smaller TSFs and clean-up material contribute about 11% of the total Mineral Resource estimates
by
tonnage.
The
Mineral
Resource
estimates
in
these
smaller
dumps
pose
a
less
than
material
risk
to
Ergo. Their Mineral Resource
was estimated from survey information
,
production and/or historical
data,
applying straight arithmetic average
s
as the TSFs or clean-up
sites are too small to be
evaluated by 3D
modelling. The QP considered the inclusion
of the TSFs and
clean-up operations as appropriate and has
conducted verification
checks to
support their
inclusion.
The Mineral
Resource estimates
of these
TSFs
and clean-up operations are not discussed
individually,
but they are part of the total
Mineral Resource
for Ergo.
11.1
Volume Modelling
For all significant TSFs, three-dimensional (3D) modelling
was completed using drill hole information and
survey data. Volumes were
estimated using a top
surface defined by a
ground survey and
associated
digital terrain model. The bases
of the TSFs were
defined by the drill hole
data and the edges of
the TSFs.
All
drill
holes
were drilled
to intersect
soil at
the
base of
the
TSFs. The
block
models were
constructed
inside of this volume. Tonnages and grades were then
extracted from the block models.
11.2
Bulk Dry Density
An average dry bulk density of 1.42t/m
3
described in Item 7.17 was applied to all the
TSFs and the sand
dumps. The tons were reported as dry tons.
11.3
Exploratory Data Analysis
Exploratory data analysis
was done on
raw and composited
gold data. Samples were
collected at 1.5m
intervals.
For
IDW
estimation
method,
the
sample
lengths
were
adequate.
The
samples
were
further
composited to 6m to allow for NN estimation
as the modelled blocks were 6m high
to represent bench
height.
Samples
were
composited
based
on
mean
sea
level
to
mimic
deposition.
This
allowed
for
estimations to be carried out based on the levels.
The requirement for
high-grade capping
was assessed to
ascertain the reliability
and spatial clustering
of
the
high-grade
data.
The
steps
completed
as
part
of
the
high-grade
capping
assessment
are
summarized below:
●
review of the data to identify any
data that deviates from the general
data distribution. This was
completed using histograms and log probability plots;
●
review of plots comparing the
contribution to the mean and
standard deviation of the highest-
grade data; and
●
visual review in 3D to allow assessment of the clustering
of the higher-grade data.
11.4
Estimation Techniques
The estimation was constrained by
the mineralization interpretations. The
statistical characteristics of the
available
sample
information
and
the
spatial
distribution
aided
the
definition
of
the
estimation
parameters, such as search volume and orientation
of the search ellipses.
Technical Report Summary of the material Tailings Storage
Facilities
77
The
IDW
(to
the
power
of
2)
and
NN
method
of
estimation
were
chosen
as
the
most
appropriate
methods for evaluation
of TSFs and
sand dumps,
as the dataset
for each TSF
and sand dump
is generally
homogeneous (laterally), grade variations are small due to deposition technique and the drill holes are
well
spread
and
spacing
is
moderately
wide.
The
methods,
when
applied
appropriately,
retain
the
grade
variation
of
the
deposit,
as
opposed
to
an
arithmetic
average,
and
is
simpler
and
more
appropriate
for
TSF
or
sand
dump
evaluation
than
other
advanced
estimation
techniques
such
as
Ordinary Kriging.
These estimation
techniques have
been found
to be
reliable by
Ergo over
the last
15 years
of mining
TSFs and sand dumps.
Hard
domain
boundaries
were
used
throughout,
preventing
samples
lying
outside
the
domain
from
being
used
for
the
estimation
meaning
slime
and
soil
samples
were
separated
during
the
estimation
process. A
three-pass estimation
strategy was
applied to
each zone,
applying an
expanded and
less
restrictive sample search to the second and subsequent estimation passes
and only considering blocks
not previously assigned
an estimate. However,
more than 80%
of the estimates were
completed in the
first pass.
A record
was
kept
of the
number
of
samples
used
to
estimate
the
grade
into a
block.
The
variance of each block and the search
volume that satisfied the criteria used
to select samples for use
in the estimation of each block.
11.5
Modelling and Estimation Parameters
The parent
block size
for all
the TSFs
and sand
dumps was
largely based
on the
average drill
spacing
and sample compositing interval.
The height of the
original dump benches is
approximately 5m to 6m.
The parent
block size
is selected
to estimate
the deposit
approximates
half the
drill hole
spacing and
maps the bench height. Sub-blocking was allowed for a good
volume definition.
11.6
Model Validation
A
routine
validation
process
was
followed
for
all
the
TSFs
and
sand
dumps.
All
relevant
statistical
information was recorded to enable validation and
review of the estimates.
The recorded information included:
●
the number of samples used per block estimate;
●
average distance to samples per block estimate;
●
estimation flag to determine in which estimation
pass a block was estimated;
and
●
the number of drill holes
from which composite data were used
to complete the block estimate.
Technical Report Summary of the material Tailings Storage
Facilities
78
The estimates were reviewed visually and
statistically prior to being accepted. The review
included the
following activities:
●
comparison of
volume estimates
between the
block model,
the 3D
wireframe model
and the
surveyor's report;
●
check
for global
bias
through
comparison
of the
estimate
versus
the
mean
of the
composite
dataset, including weighting where appropriate to account
for data clustering;
●
histogram comparison of grade block distribution versus composite
grade distribution;
●
visual checks of cross-sections, long-sections and
plans;
and
●
where
production
data
was
available,
reconciliation
was
carried
out
as
part
of
the
model
validation process.
Alternative estimates were
also completed to test
the sensitivity of the
reported model to
the selected
interpolation
parameters.
An
insignificant
amount
of
variation
in
overall
grade
was
noted
in
the
alternate
estimations.
The
results
were
satisfactory
for
the
level
of
accuracy
anticipated
for
TSF
evaluation.
11.7
Technical and Financial Parameters
In determining the cut-off grades of the Mineral Resources, the QP applied the data presented in Table
11.1.
The QP considered
the gold price
,
exchange rate and
working cost per
ton (long-term
prices as at
30
June
2022),
as
applied
reasonable
for
use
in
declaring
the
Mineral
Resources.
Justification
for
the
financial parameters used is detailed in Item 16. Additional technical parameters per TSF or sand dump
are
presented
in
the
relevant
items.
The
QP
considered
both
technical
and
financial
parameters
(infrastructure, mine design and planning,
processing plant, environmental compliance and permitting)
to justify the reasonable prospects for
economic extraction. All complexes except Crown and Grootvlei
Complexes have
studies done
to a
PFS level
of accuracy
(i.e., +/-
25%). For
the Crown
and Grootvlei
Complexes,
initial assessments were completed.
Table 11.1:
Financial and Technical Data considered for Mineral Resource
Element
Unit
Value
Mineral Resource Gold Price
USD/oz
1,823
Mineral Resource Gold Price
ZAR/kg
914,294
Exchange Projection
ZAR/USD
15.60
Working Costs per Ton (slimes)
ZAR/t
70.76
Working Costs per Ton (sand)
ZAR/t
204.46
Source: DRDGOLD, 2022
The QP has considered
that Ergo does not
selectively mine a
TSF. The average grade
of the TSF is used
to determine whether or
not a TSF is mined
in its entirety.
Where the average grade
of the TSF is above
the cut-off grade
,
all the
material in
the TSF or
sand dump
is considered
to be
mined. The
QP applied
no block cut-off.
Technical Report Summary of the material Tailings Storage
Facilities
79
A
cut-off
grade
is
also
determined
per
TSF
or
sand
dump.
A
TSF
may
report
an
average
gold
grade
below a
cut-off grade,
but when
included in
a complex,
the total
complex should
be above
the cut-
off grade. See
Table 11.2 for
the cut-off information.
The QP determined
cut-off grades using
the formula
presented in Item 12.2.
Table 11.2:
Mineral Resource
Estimate Cut-off Grades
TSF/Sand Dump
Recovery
Cut-off Grade
(%)
(g/t)
Crown Complex
3L8 (GMTS)
41
0.189
3L7 (Mooifontein)
40
0.193
3L5 (Diepkloof)
36
0.215
Average for the Complex
0.199
City Deep Complex
4L3
60
0.129
4L4
41
0.189
4L6
58
0.133
Average for the Complex
0.150
Knights Complex
4L14
44
0.176
4L50
35
0.221
Average for the Complex
0.199
Ergo Complex
Rooikraal
33
0.235
7L15
47
0.165
Average for the Complex
0.200
Marievale Complex
7L4
52
0.149
7L5
34
0.228
7L6
30
0.258
7L7
39
0.198
Average for the Complex
0.208
Grootvlei Complex
6L16
33
0.235
6L17
47
0.165
6L17A
39
0.198
Average for the Complex
0.199
5A10/5L27 Sand Dump
5A10/5L27
55
0.407
Daggafontein TSF
Daggafontein
35
0.221
Source: The RVN Group, 2022
The following statements apply
to all Mineral Resources tables:
●
Mineral Resources are not Mineral Reserves;
●
Mineral Resources are reported inclusive and exclusive
of Mineral Reserves;
Technical Report Summary of the material Tailings Storage
Facilities
80
●
Mineral Resources have been reported in accordance
with Subpart 1300 of Regulation S-K;
●
Mineral
Resources
were
estimated
using
the
USD1,823/oz,
ZAR15.60/USD
and
ZAR914,294/kg
financial parameters;
●
the recovery information is presented in Table 11.2;
●
the reference point is
in situ
;
●
a troy ounce = 31.1034768g;
and
●
quantities
and
grades
were
rounded
to
reflect
the
accuracy
of
the
estimates;
any
apparent
errors are insignificant.
11.8
Uncertainties and Classification Criteria
Definitions
for
Mineral
Resource
categories
used
in
this
report
are
those
defined
by
the
Security
and
Exchange
Commission in
Subpart 1300
of Regulation
S-K. Mineral
Resource Estimates
are
classified
to
reflect
the
increased
level
of
geological
confidence
into
Inferred,
Indicated
and
Measured
Mineral
Resource categories.
By
their
nature,
all
Mineral
Resource
estimates
carry
an
inherent
amount
of
risk
and
uncertainty
depending on
various factors,
including interpretation
of data,
drilling data
quality, uncertainty
in the
survey and metallurgical test work data collected and the modelling process.
However, Ergo has been
in operation for more than 20 years treating TSFs and sand
dumps and has sufficiently mitigated Mineral
Resource
risks
through
obtaining
sufficient
sampling
information.
Some
uncertainties
were
resolved
through reconciliations,
process improvement and the use of experienced personnel in data collection
and interpretation.
The
QP
based
the
Mineral
Resource
categorization
on
the
robustness
of
the
various
data
sources
available,
the
confidence
of
the
geological
interpretation
and
various
estimation
parameters
(e.g.,
distance
to
data,
number
of
data,
maximum
search
radii
etc.)
and
reconciliation
data
where
it
is
available.
The QP considers
the Mineral
Resource classification
as a function
of the confidence
of the
whole
process
from
drilling,
sampling,
geological
understanding
and
variables
relationships.
TSFs
and
sand dumps are evaluated
individually and there
are no blanket
classification parameters as
TSFs and
sand dumps
are different
.
However, drill
hole spacing
and data
quality contribute
significantly
to the
classification confidence.
Each TSF or sand dump has its classification criteria
discussed separately.
The Mineral Resource confidence is assessed via internal peer
reviews, with no material issues identified.
Mineral Resources have reasonable prospects for
economic extraction and the QP
considered a range
of mining, processing, infrastructural, social, environmental
and permitting factors.
Technical Report Summary of the material Tailings Storage
Facilities
81
11.9
Crown Complex
11.9.1
Exploratory Data Analysis
Statistical analysis of data was completed as presented in
Figure 11.1 to Figure 11.8. Data was analyzed
as raw, capped and composites. There was
no material changed between the data sets. The
data sets
show positively skewed distribution.
Based on
the high-grade
cap investigations,
high-grade caps
were selected
and applied
to the
raw
dataset:
●
3L7 (Mooifontein): gold grades were capped at 0.60g/t;
●
3L8 (GMTS): gold grades were capped at 0.60g/t;
and
●
3L5
(Diepkloof):
two
domains
(compartments)
were
modelled
and
gold
grades
were
also
capped at 0.60g/t.
Capping was only applied to raw data and its impact
on the mean was immaterial.
3L5
(Diepkloof
TSF)
was
domained
into
two
areas
because
of
physical
separation
between
the
two
compartments (Homestead and Diepkloof).
Figure 11.1:
3L7 (Mooifontein): Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
82
Figure 11.2:
3L7 (Mooifontein): Distribution of Composited Gold Data
Source: The RVN Group, 2022
Figure 11.3:
3L8 (GMTS): Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
83
Figure 11.4:
3L8 (GMTS): Distribution of Composited Gold Data
Source: The RVN Group, 2022
Figure 11.5:
3L5 (Diepkloof:
Diepkloof):
Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
84
Figure 11.6:
3L5 (Diepkloof:
Diepkloof):
Distribution of Composited Gold Data
Source: The RVN Group, 2022
Figure 11.7:
3L5 (Diepkloof:
Homestead):
Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
85
Figure 11.8:
3L5 (Diepkloof:
Homestead):
Distribution of Composited Gold Data
Source: The RVN Group, 2022
11.9.2
Modelling and Estimation Parameters
Half the drill hole spacing
was chosen as the block
size. Block size of 100m-by-100m-by-6m
was chosen
for the TSFs. Sub-celling was allowed for better volume definition.
The sample search parameters are supplied in Table
11.3.
Table 11.3:
Search Parameters: Inverse Distance Estimation
Method
TSF
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
X
(m)
Y
(m)
Z
(m)
3L7 (Mooifontein)
Mooifontein
1
300
300
6
5
20
2
600
600
12
5
20
3
900
900
18
5
20
3L8 (GMTS)
GMTS
1
400
400
10
4
10
2
800
800
20
4
10
3
1,200
1,200
30
4
10
3L5 (Diepkloof)
Homestead
1
400
400
10
4
10
2
800
800
20
4
10
3
1,200
1,200
30
4
10
Diepkloof
1
400
400
10
4
10
2
800
800
20
4
10
3
1,200
1,200
30
4
10
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
86
11.9.3
Technical and Economic Factors
11.9.3.1
Site Infrastructure
Crown Complex is located
in a well-developed area
(Johannesburg) with most mining
infrastructure in
place.
Johannesburg
is
a
megacity
and
is
one
of
the
100
th
largest
urban
cities
in
the
world.
Johannesburg was established in the 1880s following
the discovery of gold.
Roads:
Access
to
the
Crown
Complex
is
via
the
N1
highway
and
a
network
of
the
well-maintained
paved road systems.
Power:
Power requirements
are primarily
for the operation
of pumps
and site
offices. Power
is sourced
from
the
national
supplier,
the
Electricity
Supply
Commission
(Eskom).
There
is
power
supply
from17#
substation to the surrounding areas and the TSFs.
Site
Offices
and
Workshop:
Site
offices
are
typically
established
by
mining
contractors
as
part
of
the
mining
contract.
Workshops
for
maintenance
of
roads,
pumps
and
pipelines
are
based
at
the
Ergo
processing plant and no additional infrastructure is required.
Crown Complex is situated in the City of Johannesburg, so
other specialized services could be sourced
from the private workshops.
Pumps and Pipelines:
Before mining could start, the pump station and pipeline to Ergo processing plant
in Brakpan
should be completed.
A pipeline of
approximately 20km
will be required
to supply
slime to
City Deep. There
is already a pipeline
infrastructure to transport slime
to Ergo Plant from
City Deep; this
may need to be upgraded along with a water supply
pipeline at a later stage.
Water:
Water
is
required
during
mining
as
hydraulic
mining
method
is
suitable
for
Crown
Complex.
A
Mining
Right renewal
application
has been
launched.
Crown Complex
has
the majority
of the
water
uses authorized and
would only require
minor amendments, but this
would only be able
to 100%
defined
when the entire
scope and design
of the project
is finalized. Ergo
is confident that
a water use
license
will be issued.
Tailings Deposition
Site:
Ergo has
sufficient tailings
deposition capacity
at their
Brakpan/Withok tailings
deposition facility
to accommodate
all material
from Crown
Complex,
in addition
to the
tonnages in
the LoM plan if the final design of
the Brakpan/Withok TSF is approved
and implemented. Refer to Item
15.7 and 19.3.2 for more detail on deposition plans.
11.9.3.2
Mine Design and Planning
Hydraulic
mining
is
suitable
for
Crown
Complex.
Hydraulic
mining
can
loosely
be
defined
as
the
excavation
of
material
from
its
in
situ
state
using
water.
A
stream
of
water
is
directed
at
the
tailings
material
with
the
purpose
of
mechanically
breaking
and/or
softening
the
material
so
that
it
can
be
carried away by the
water flow. The
application or effectiveness of the
method is a function
of a variety
of factors
ranging
from
the
size, velocity
and
pressure
of
the
water
stream
to the
location,
hardness,
particle size and moisture content of the material to be mined.
Technical Report Summary of the material Tailings Storage
Facilities
87
Hydraulic mining is
typically undertaken using
100mm or 150mm
monitor guns with
increased production
achieved
by
the
inclusion
of
additional
units.
This
provides
a
high
degree
of
flexibility
that
allows
simultaneous mining at a number of
points over a wide range
of production rates. Consequently, grade
blending is readily achievable.
A production rate of 3 x 600kt/m is assumed from Crown
Complex due to pipeline capacity.
11.9.3.3
Processing Plant
Crown Complex material could be
processed at Ergo’s processing plant
as discussed in Item
10 and the
results
presented
in
Table
10.1.
The
slime
material
is
not
significantly
different
to
the
slimes
material
processed at the Ergo processing plant.
The Ergo processing plant details are in Item 14.
11.9.3.4
Environmental Compliance and Permitting
A
Mining
Right
renewal
application
was
launched
with
the
DMRE.
Compliance
and
permitting
are
discussed in Item 3.2 and 17.
11.9.3.5
Initial Assessment Results
The QP’s opinion is that
there is a reasonable prospect
for economic extraction based on
the total mix
of technical and financial factors discussed. A cut-off grade
is discussed in Item 12.2.11.7
11.9.4
Mineral Resource Classification Criteria
A
list
of
the
criteria
used
to
classify
the
Mineral
Resources
is
given
in
Table
11.4.
Applying
these
confidence
levels,
Mineral
Resource
classification
codes
were
assigned
to
the
block
model.
A
low
confidence
in
one of
the
listed
items
will
mean
classification
is downgraded
to Inferred,
a moderate
confidence in at least one item will mean a property
is Indicated while all highs mean the property is
in
the Measured Mineral Resource category.
Technical Report Summary of the material Tailings Storage
Facilities
88
Table 11.4:
Confidence Levels for Key Criteria for Mineral Resource
Classification
Items
Discussion
Confidence
Drilling Techniques
RC drilling technique to international standards
High
Logging
Detailed logging throughout
High
Drill Sample Recovery
The sample recovery was considered satisfactory and was
acceptable for mineral resource estimation
High
Sub-sampling Techniques
and Sample Preparation
Material has previously been processed and quartering was
applied
High
Quality of Assay Data
Available data is of robust quality however there is a relatively high
variability in the lowest grade assays
High
Verification of Sampling
and Assaying
A comprehensive QC program implemented during exploration
High
Location of Sampling
Points
Survey of all collars and TSFs surfaces
High
Data Density and
Distribution
Data points were well spread, though widely spaced.
Approximately 200m-by-200m spacing was followed
Moderate
Database Integrity
Errors identified and rectified
High
Geological Interpretation
Geometry is known accurately
High
Bulk Density
A mean density of 1.42t/m
3
was considered reasonable
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and Modelling
Techniques
NN and Inverse Distance
High
Source: The RVN Group, 2022
The
drill
hole
spacing
was
approximately
200-by-200m
on
all
the
TSFs.
With
this
grid,
the
grade,
floor
elevation
and
TSF
geometry
were
estimated
with
sufficient
confidence
to
allow
the
application
of
modifying factors in sufficient detail
to support mine planning and
evaluation of the economic viability
of
the
TSFs.
All
TSFs’
material
was
classified
as
Indicated
Mineral
Resources.
No
Measured
Mineral
Resource was
declared
as the
drill
space is
still too
wide to
conclusively
define grade
continuity and
volume. No Inferred was declared as drilling provided
sufficient information.
The data
or supporting
information is
derived
from the
adequately
detailed
and reliable
exploration,
sampling
and testing
and is
sufficient to
assume
geological
and grade
or quality
continuity between
points of observation.
11.9.5
Mineral Resource Statement
As
no
Mineral
Reserve
was
declared,
inclusive
is
equal
to
exclusive
Mineral
Resource
for
the
Crown
Complex (Table 11.5).
Technical Report Summary of the material Tailings Storage
Facilities
89
Table 11.5:
Crown Complex Mineral Resource Estimate (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June
2021 (Exclusive)
Mineral Resources as at 30 June
2022 (Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
Measured Mineral Resources
-
-
-
-
-
-
Mooifontein (3L7)
Indicated
67,559
0.23
499,577
67,559
0.23
499,577
GMTS (3L8)
Indicated
107,450
0.25
863,649
107,450
0.25
863,649
Diepkloof (3L5)
Indicated
97,988
0.23
724,589
97,988
0.23
724,589
Sub-total Indicated Mineral
Resources
272,997
0.24
2,087,815
272,997
0.24
2,087,815
Sub-total Measured and
Indicated Mineral Resources
272,997
0.24
2,087,815
272,997
0.24
2,087,815
Inferred Mineral Resources
-
-
-
-
-
-
Total Mineral Resource
272,997
0.24
2,087,815
272,997
0.24
2,087,815
Source: The RVN Group, 2022
11.9.6
Mineral Resource Changes
There was
no change
in Mineral
Resource as
no drilling,
mining or
additional deposition
was done
on
Crown Complex.
11.9.7
Mineral Resource Risks and Uncertainty
The renewal of the Mining Right
for the Crown Complex is a
risk. The application to renew
was launched
in 2014 and
Ergo has since
been constantly engaging the
DMRE. This report
has considered section
24(5)
of the MPRDA, as amended; as quoted below:
“
A mining right in respect of which
an application for renewal has
been lodged shall despite its expiry
date remain in force until such time as such application has
been granted or refused.
”
The QP classified the overall Mineral Resource risk as medium due
to lower grades and permitting status
of the Crown Complex.
In the opinion of the QP, no further technical work is required as the drilling
program provided sufficient
data to define continuity.
11.10
City Deep Complex
11.10.1
Exploratory Data Analysis
Figure 11.9 to Figure 11.14 show the frequency
distributions
of the gold grades on 4L3, 4L4
and 4L6. Data
was analyzed as
raw, capped and composites.
There was no
material changed between the
data sets.
The data sets show positively skewed distribution.
Based on
the high-grade
cap investigations,
high-grade caps
were selected
and applied
to the
raw
dataset. A little/insignificant reduction in the available
metal is noted.
●
4L3: capped at 0.65g/t Au;
●
4L4: capped at 0.65g/t Au; and
Technical Report Summary of the material Tailings Storage
Facilities
90
●
4L6: capped at 0.50g/t Au.
Figure 11.9:
4L3: Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
91
Figure 11.10:
4L3: Distribution of Composited Gold Data
Source: The RVN Group, 2022
Figure 11.11:
4L4: Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
92
Figure 11.12:
4L4: Distribution of Composited Gold Data
Source: The RVN Group, 2022
Figure 11.13:
4L6:
Distribution of Raw Gold Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
93
Figure 11.14:
4L6: Distribution of Composited Gold Data
Source: The RVN Group, 2022
11.10.2
Modelling and Estimation Parameters
A block
model
with
100m-by-100m
blocks
was constructed
for
4L3, 4L4
and
4L6 inside
the
respective
volumes. Tonnages
and grades
were estimated
into the
block model.
The parent
block sizes
selected
to estimate
the deposit
approximates
the
drill
hole
spacing.
The tailings
bench
heights
are 5m
to
8m
high. The QP selected 6m in the Z direction for the City
Deep Complex to correspond with the average
bench height.
The sample search parameters are supplied in the
Table 11.6.
Table 11.6:
Search Parameters: Inverse Distance Estimation
Method
TSF
Estimation Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
X
(m)
Y
(m)
Z
(m)
4L3
1
400
400
10
4
10
2
800
800
20
4
10
3
1,200
1,200
30
4
10
4L4
1
400
400
10
4
10
2
800
800
20
4
10
3
1,200
1,200
30
4
10
4L6
1
400
400
10
4
10
2
800
800
20
4
10
3
1,200
1,200
30
4
10
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
94
11.10.3
Technical and Economic Factors
Item 13 to Item 19 were considered in declaring the Mineral
Resource estimates.
11.10.4
Mineral Resource Classification Criteria
An additional list of the
criteria used by the
QP to classify the Mineral
Resource estimates in addition
to
the
statistical
parameters
is
given
in
Table
11.7.
Applying
these
confidence
levels,
Mineral
Resource
classification codes were
assigned to the
block model. A
low confidence in
one of the
listed items will
mean classification is downgraded to Inferred, a moderate confidence in at least one item will mean a
property is Indicated while all highs mean the property
is in the Measured Mineral Resource category.
Table 11.7:
Confidence Levels of Key Criteria for Classification
of the TSFs Mineral Resources
Items
Discussion
Confidence
Drilling Techniques
Auger to industry standards
High
Logging
Detailed logging throughout
High
Drill Sample Recovery
The sample recovery is estimated as >90% and was considered
acceptable for Mineral Resource estimation
High
Sub-sampling
Techniques and
Sample Preparation
Material has previously been processed and was submitted directly
for sampling
High
Quality of Assay Data
Available data is of robust quality
High
Verification of
Sampling and
Assaying
A comprehensive QC program was implemented
High
Location of Sampling
Points
Survey of all collars and TSF surfaces
High
Data Density and
Distribution
Approximately 100m-by-100m spacing was followed
high
Geological
Interpretation
Geometry is known accurately
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and
Modelling Techniques
Inverse distance used for resource declaration. NN used for validation
High
Source: The RVN Group, 2022
The QP classified
the Mineral
Resources into the
Measured Mineral
Resource Category
as the drill
hole
spacing
was
tight
enough
(approximately
100m
apart)
to
provide
sufficient
evidence
of
grade
continuity and estimate
tons with high
confidence.
No Indicated and
Inferred Mineral
Resources were
declared.
11.10.5
Mineral Resource Statement
Table 11.8 to Table 11.9 present Mineral Resources
for 4L3, 4L4 and 4L6 as at 30 June 2022.
Table 11.8:
City Deep Complex Mineral Resource Estimates
(Inclusive)
TSF
Mineral Resource
Category
Mineral Resources as at 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
Au
Content
Tons
Au
Content
Technical Report Summary of the material Tailings Storage
Facilities
95
(kt)
(g/t)
(oz)
(kt)
(g/t)
(oz)
4L3
Measured
13,134
0.32
135,126
13,134
0.32
135,126
4L4
Measured
4,738
0.32
48,746
4,738
0.32
48,746
4L6
Measured
2,410
0.31
24,020
2,410
0.31
24,020
Sub-total Measured Mineral
Resources
20,282
0.32
207,891
20,282
0.32
207,891
Indicated Mineral Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral Resources
20,282
0.32
207,891
20,282
0.32
207,891
Inferred Mineral Resources
-
-
-
-
-
-
Total Mineral Resource
20,282
0.32
207,891
20,282
0.32
207,891
Source: The RVN Group, 2022
Table 11.9:
City Deep Complex Mineral Resource Estimates
(Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
4L3
Measured
-
-
-
-
-
-
4L4
Measured
-
-
-
-
-
-
4L6
Measured
-
-
-
-
-
-
Sub-total Measured
Mineral Resources
-
-
-
-
-
-
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
-
-
-
-
-
-
Inferred Mineral
Resources
-
-
-
-
-
-
Total Mineral Resource
-
-
-
-
-
-
Source: The RVN Group, 2022
11.10.6
Mineral Resource Changes
There was no
change in
Mineral Resources
as no drilling,
mining or additional
deposition was done
on
4L3, 4L4
and 4L6 TSFs.
11.10.7
Mineral Resource Risks and Uncertainty
The
QP’s
opinion
is
that
the
overall
grade
and
tonnage
estimates
are
reasonable
for
mine
planning
based on the drill hole data and assay statistics.
The gold price fluctuations present the main risk to the declared
Mineral Resource estimates.
Risks
of
grade,
continuity
of
mineralization
and
tons
were
mitigated
through
the
reasonable
drilling
space, validation procedures, metallurgical testing, advanced statistical
analyses and the use of
robust
modelling techniques.
The QP classified the
overall Mineral Resource
risk as low. In
the opinion of
the QP, no further
technical
work is required as the drilling program provided enough data
to define continuity.
Technical Report Summary of the material Tailings Storage
Facilities
96
11.11
Knights Complex
11.11.1
Exploratory Data Analysis
Statistics of the sample population from raw, capped and composited data are
given in Figure 11.15 to
Figure 11.28. At 4L14, both slime and
soil were mineralized with soil having
a maximum grade of 1.96g/t
Au. The spread of
both the slimes
and soil data
is not large
which indicates that
the grade variability
is
low. The
gold grades for
soil were
capped at 0.94g/t
to reduce the
over-estimation of soil
gold resources.
Capping
reduced
the
mean
by
about
10%;
however,
this
is
due
to
lack
of
data
rather
than
a
large
volume of
high-grade material.
The slimes
grades were
composited into
6m intervals.
The soil
domain
was
not
composited
as
there
was
not
enough
data.
The
6m
composites
were
based
on
numerous
statistical tests and bench height. The bench height is 5m
to 6m high.
Figure 11.15:
4L14: Distribution of Slime Raw Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
97
Figure 11.16:
4L14: Log Distribution of Slime Raw Data
Source: The RVN Group, 2022
Figure 11.17:
4L14: Distribution of Slime 6m Composited Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
98
Figure 11.18:
4L14: Log Distribution of Slime 6m Composited Data
Source: The RVN Group, 2022
Figure 11.19:
4L14: Distribution of Soil Raw Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
99
Figure 11.20:
4L14: Log Distribution of Soil Raw Data
Source: The RVN Group, 2022
Figure 11.21:
4L14: Distribution of Soil Raw Capped Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
100
Figure 11.22:
4L14: Log Distribution of Soil Raw Capped Data
Source: The RVN Group, 2022
Figure 11.23:
4L50: Log Distribution of Raw Slime Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
101
Figure 11.24:
4L50: Distribution of Raw Slime Raw Data
Source: The RVN Group, 2022
Figure 11.25:
4L50: Log Distribution of Raw Capped Slime Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
102
Figure 11.26:
4L50: Distribution of Raw Capped Slime Data
Source: The RVN Group, 2022
Figure 11.27:
4L50: Distribution of 3m Composited Slime Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
103
Figure 11.28:
4L50: Log Distribution of 3m Composited Slime Data
Source: The RVN Group, 2022
11.11.2
Modelling and Estimation Parameters
4L14:
The parent
block sizes for
the TSFs were
mostly based on
the average drill
spacing and compositing
interval. The
height of
the dump
benches is
around 5m
to 6m.
The parent
block sizes selected
to estimate
the
deposit
approximates
half
the
drill
hole
spacing.
Sub-blocking
was
allowed
for
good
volume
definition. Soil was modelled as a
separate domain. Soil was modelled because it
had high gold values,
the QP attributed this high gold value to gold remobilization
from the TSF.
Estimation Parameters for 4L14 are given in Table
11.10 and Table 11.11.
Table 11.10:
4L14: Search Parameters: Nearest Neighbor Estimation Method
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Composites
per Drill Hole
X
(m)
Y
(m)
Z
(m)
Slime
1
400
400
50
1
1
1
2
800
800
100
1
1
1
3
1,200
1,200
150
1
1
1
Soil
1
400
400
50
1
1
1
2
800
800
100
1
1
1
3
1,200
1,200
150
1
1
1
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
104
Table 11.11:
4L14: Search Parameters: Inverse Distance Estimation
Method
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Composites
per Drill Hole
X
(m)
Y
(m)
Z
(m)
Slime
1
500
500
12
5
10
2
2
1,000
1,000
24
5
10
2
3
1,500
1,500
36
5
10
2
Soil
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Source: The RVN Group, 2022
4L50:
The parent block sizes for the 4L50 TSF were mostly based on the average drill spacing and bench
height. The parent block sizes
selected to estimate the deposit approximates the
borehole spacing. The
bench height is 2m to 4m high.
Sub-blocking was allowed to improve volume
representation within the
interpreted wireframe models of the dump top and
bottom surfaces.
A comparison
of the
2008 and
2016 drillhole
information
showed that
the
base of
the
dump was
not
properly defined
in the
2008 drilling.
There appeared
to be
over-drilling
or extra
samples at
the base.
Due
to
this
problem,
it
was
decided
to
map
the
base
of
the
dump
using
the
2016
to
2017
drilling
campaign data only. There is high confidence in the logging
data from the 2016 drilling campaign.
The sample search parameters are supplied in Table
11.12 and Table 11.13.
Table 11.12:
4L50: Search Parameters: Nearest Neighbor Estimation Method
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Composites
per Drill Hole
X
(m)
Y
(m)
Z
(m)
Slime
1
400
400
50
1
1
1
2
800
800
100
1
1
1
3
1,200
1,200
150
1
1
1
Source: The RVN Group, 2022
Table 11.13:
4L50: Search Parameters: Inverse Distance Estimation Method
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Composites
per Drill Hole
X
(m)
Y
(m)
Z
(m)
Slime
1
500
500
6
5
10
2
2
1,000
1,000
12
5
10
2
3
1,500
1,500
24
5
10
2
Source: The RVN Group, 2022
A number of search parameters were tested; optimum parameters
were chosen by the QP.
Technical Report Summary of the material Tailings Storage
Facilities
105
11.11.3
Technical and Economic Factors
Item 13
to Item 19
were considered
in declaring
the Mineral
Resource Estimates.
The technical
studies
were done at a PFS level. As at 30June 2022, 4L50
was being mined.
11.11.4
Mineral Resource Classification Criteria
The
4L14
and
4L50
TSFs
were
classified
using
a
number
of
criteria
including
data
density,
estimation
statistics and
TSF knowledge
and interpretation.
For classification
purpose, blocks
estimated within
the
first search radius were
classified as Measured
Mineral Resources.
The TSFs were
classified as Measured
Mineral Resources.
A list of
the criteria used
to classify the
Mineral Resources in
addition to the
statistical parameters,
is given
in
Table
11.14
below.
Applying
these
confidence
levels,
Mineral
Resource
classification
codes
were
assigned
to
the
block
model.
A
low
confidence
in
one
of
the
listed
items
will
mean
classification
is
downgraded to Inferred, a moderate confidence in at least one item will mean a property is Indicated
while all highs mean the property is in the Measured Mineral
Resource category.
Table 11.14:
Confidence
Levels
of
Key
Criteria
for
Classification
of
the
4L14and
4L50
TSFs
Mineral Resources
Items
Discussion
Confidence
Drilling Techniques
Auger to international standards
High
Logging
Detailed logging throughout
High
Drill Sample Recovery
The
sample
recovery
is
estimated
as
>90%
and
is
considered
acceptable for Mineral Resource estimation
High
Sub-sampling Techniques
and Sample Preparation
Material
has
previously
been
processed
and
can
be
submitted
directly for sampling
High
Quality of Assay Data
Available
data
is
of
robust
quality
however
there
is
a
relatively
high variability in the lowest grade assays
High
Verification of Sampling and
Assaying
A comprehensive QC program implemented during exploration
High
Location of Sampling Points
Survey of all collars and TSFs surfaces
High
Data Density and
Distribution
Drilled with auger drill holes at 100m-by-100m
High
Database Integrity
Errors identified and rectified
High
Geological Interpretation
Geometry is known accurately
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and Modelling
Techniques
NN and Inverse Distance Squared
High
Source: The RVN Group, 2022
Both TSFs were classified
as Measured due to
a tight drill
hole spacing of <100m
and high data
quality.
This
spacing
enabled
the
QP
to
estimate
tonnage
and
grade
continuity
with
high
confidence.
Production
data
from
4L50
matches
well
with
the
estimated
values
(Figure
11.29).
No Indicated
and
Technical Report Summary of the material Tailings Storage
Facilities
106
Inferred Mineral
Resources were declared
as confidence
in the data
and estimation process
followed
were high.
Figure 11.29:
4L50: Head Grade versus Modelled Average Gold Grade
Source: The RVN Group, 2022
11.11.5
Mineral Resource Statement
Table 11.15 and
Table 11.16 present the Mineral Resource for 4L14 and
4L50.
Table 11.15:
Knights Complex Mineral Resource Estimates (Inclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
4L14
Measured
6,638
0.29
61,891
6,638
0.29
60,824
4L50
Measured
6,756
0.26
56,475
3,418
0.26
27,216
Sub-total Measured
Mineral Resources
13,394
0.27
118,366
10,056
0.28
88,040
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
13,394
0.27
118,366
10,056
0.28
88,040
Inferred Mineral
Resources
-
-
-
-
-
-
Total Mineral Resource
13,394
0.27
118,366
10,056
0.28
88,040
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
107
Table 11.16:
Knights Complex Mineral Resource Estimates (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
4L14
Measured
-
-
-
-
-
-
4L50
Measured
-
-
-
-
-
-
Sub-total Measured
Mineral Resource
-
-
-
-
-
-
Indicated Mineral
Resource
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
-
-
-
-
-
-
Inferred Mineral Resource
-
-
-
-
-
-
Total Mineral Resources
-
-
-
-
-
-
Source: The RVN Group, 2022
11.11.6
Mineral Resource Changes
Mining
on
4L50
TSF resulted
in
a
depletion
of
the
Mineral
Resource.
Depletion
and
reconciliation
are
explained
in
13.
The
modeled
average
gold
grade
correlated
well
with
production
data
(Figure 11.29). No mining has taken place on 4L14 TSF.
11.11.7
Mineral Resource Risks and Uncertainty
The
QP’s
opinion
is
that
the
overall
grade
and
tonnage
estimates
are
reasonable
for
mine
planning
based on the drill hole data and assay statistics.
The gold price fluctuations present the main risk to the declared
Mineral Resource estimates.
Risks of grade, continuity of mineralization and tonnage
were mitigated through the reasonable drilling
spacing,
validation
procedures,
metallurgical
testing,
advanced
statistical
analyses
and
the
use
of
robust modelling techniques.
The QP classified the
overall Mineral Resource
risk as low. In
the opinion of
the QP, no further
technical
work is required as the drilling program provided enough data
to define continuity.
11.12
Ergo Complex
11.12.1
Exploratory Data Analysis
11.12.1.1
Rooikraal
Exploratory
data
analysis
was
done
on
raw
and
composited
gold
data
(Figure
11.30
and
Figure 11.31).
The distribution
of the
raw and
composite is
symmetrical with similar
coefficient of
variation
and a low standard deviation.
Technical Report Summary of the material Tailings Storage
Facilities
108
Based on
the high-grade
cap investigations,
the QP
decided not
to apply
high-grade capping
as no
extreme values were noted.
Figure 11.30:
Rooikraal: Distribution of Raw Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
109
Figure 11.31:
Rooikraal: Log Distribution of Composited Gold Data
Source: The RVN Group, 2022
11.12.1.2
7L15
A comprehensive study on the
2015 versus the 2016 to 2017
datasets
was performed. The 2015 dataset
has higher grades than the 2016 to 2017 dataset. The 2015 dataset reported an average gold grade of
0.34g/t and the 2016 to 2017 dataset has an average
gold grade of 0.26g/t.
A decision was
made to re-drill three
drill holes and
compare the 2015
samples against the
2016 samples
in
the
same horizon.
The
2016
samples
were
split
on-site
into
three
subsamples
and
were
sent
to
two
different laboratories. One
batch was sent to
the local mine
laboratory (MAED-Ergo) and
two batches
of same
samples were
sent to
the Anglo
Lab with
completely
different sample
numbers to
avoid
the
laboratory identifying that the samples were
from the same drillholes.
The
results
of
the
re-drilling
showed
that
the
old
7L15
data
(2015)
analyzed
by
the
MAED
(Crown)
laboratory
were
over-reported
and
should
not be
used
in
the
Mineral
Resource
evaluation.
Only
the
2016 to 2017
drilling campaign dataset
could be used
for the estimation.
The MAED laboratory
analyzing
the 2016
samples
is a
new
laboratory
at the
Ergo
processing
plant
and not
the
old laboratory
at
the
Crown processing plant,
which analyzed the 2015 samples.
Domaining:
7L15 has
two physically
visible TSFs
and the
grades of
the TSFs
are different
(Figure 11
.32).
The
layering
in
each
domain
did
not
continue
into
the
other.
The
South
and
North
domains
were
separated
for
Mineral
Resource
evaluation.
The
North
TSF
(Figure
11.33
and
Figure
11.34)
has
lower
grades than the
South TSF (Figure
11.35 and Figure
11.36). The North
domain has
an average grade
of
0.23g/t Au and the South domain reported an average
grade of 0.30g/t Au.
Technical Report Summary of the material Tailings Storage
Facilities
110
Figure 11.32:
7L15: Plan showing North and South Domains
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
111
Figure 11.33:
7L15: Distribution of 2015 Raw Data - North Domain
Source: The RVN Group, 2022
Figure 11.34:
7L15: Log Distribution of 2016
Raw Data - North Domain
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
112
Figure 11.35:
7L15: Distribution of 2015 Raw Data - South Domain
Source: The RVN Group, 2022
Figure 11.36:
7L15: Log Distribution of 2016
Raw Data - South Domain
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
113
The
statistical
characteristics
of
the
North
and
South
domains
are
shown
in
Figure
11.37
to
Figure 11.40. Compositing was completed at 3m interval.
Figure 11.37:
7L15: Distribution of 3m Composited Slime Data -
South Domain
Source: The RVN Group, 2022
Figure 11.38:
7L15: Log Distribution of 3m Composited Slime
Data - South Domain
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
114
Figure 11.39:
7L15: Distribution of 3m Composited Slime Data -
North Domain
Source: The RVN Group, 2022
Figure 11.40:
7L15: Log Distribution of 3m Composited Slime
Data - North Domain
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
115
11.12.2
Modelling and Estimation Parameters
11.12.2.1
Rooikraal
The height of the original dump
benches is approximately 5m
to 6m. The parent block sizes selected
to
estimate the deposit
approximates the drill
hole spacing (at
least a drill
hole in a block)
and maps the
bench height.
A number
of search
parameters
were
tested
and
optimum parameters
were chosen
by
the
QP.
The
sample search parameters are supplied in Table 11.17.
Table 11.17:
Rooikraal: Search Parameters: Inverse Distance Estimation
Method
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Samples
Maximum
Number of
Samples
Maximum
Number of
Samples per
Drill Hole
X
(m)
Y
(m)
Z
(m)
Rooikraal
1
600
600
12
6
18
5
2
1,200
1,200
24
6
18
5
3
1,800
1,800
36
6
18
5
Source: The RVN Group, 2022
11.12.2.2
7L15
The parent block sizes
for the 7L15 TSFs
were mostly based on
the average drill spacing and
compositing
interval.
The
parent
block
sizes
selected
to
estimate
the
deposit
approximates
half
the
borehole
spacing. Sub-blocking
was allowed
for good
volume definition.
The search
parameters are
presented
in Table 11.18.
Table 11.18:
7L15: Search Parameters: Inverse Distance Estimation
Method
Domain
Estimation
Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Composites
per Drill Hole
X
(m)
Y
(m)
Z
(m)
North
1
400
400
6
2
5
-
2
800
800
12
2
5
-
3
1,200
1,200
24
2
5
-
South
1
400
400
6
2
5
-
2
800
800
12
2
5
-
3
1,200
1,200
24
2
5
-
Source: The RVN Group, 2022
11.12.3
Technical and Economic Factors
The QP used
the PFS information
(Item 13 to
Item 19) to
declare that the
Rooikraal and
7L15 TSFs have
reasonable prospects for economic extraction.
The QP opinion is that there is a reasonable prospect for economic extraction based on the total mix of
technical and economic factors discussed.
Technical Report Summary of the material Tailings Storage
Facilities
116
11.12.4
Mineral Resource Classification Criteria
A list of the
criteria used to classify the
Mineral Resources in addition to
the statistical parameters is given
in Table
11.19. Applying
these confidence
levels, Mineral
Resource classification
codes were
assigned
to the block model.
A low confidence in
one of the listed
items will mean classification
is downgraded
to Inferred, a moderate confidence in at least one item will mean a property is Indicated while all highs
mean the property is in the Measured Mineral Resource category.
Table 11.19:
Ergo: Confidence Levels for Key Criteria for Mineral Resource
Classification
Items
Discussion
Confidence
Drilling Techniques
Auger for 7L15 and for Rooikraal TSF, RC and auger drilling
techniques
were used. These methods are industry standard for
drilling TSFs
High
Logging
Detailed logging throughout
High
Drill Sample Recovery
The sample recovery was considered satisfactory and was
acceptable for Mineral Resource estimation
High
Sub-sampling Techniques
and Sample Preparation
Material has previously been processed and quartering was
applied
High
Quality of Assay Data
Available data is of robust quality however there is a relatively high
variability in the lowest grade assays
High
Verification of Sampling
and Assaying
A comprehensive QC program implemented during exploration
High
Location of Sampling
Points
Survey of all collars and TSFs surfaces
High
Data Density and
Distribution
Data points were well spread. Approximately 100m-by-100m
spacing was followed
High
Database Integrity
Errors identified and rectified
High
Geological Interpretation
Geometry is known accurately.
High
Bulk Density
A mean density of 1.42t/m
3
was considered reasonable with a
potential upside
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and Modelling
Techniques
NN and Inverse Distance
High
Source: The RVN Group, 2022
The drillhole spacing was approximately
100m-by-100m. With this grid, the
grade, floor elevation and TSF
geometry
were
estimated
with
sufficient
confidence
to
allow
the
application
of
modifying
factors
in
sufficient
detail
to
support
mine
planning
and
evaluation
of
the
economic
viability
of
the
TSF.
Some
auger drill holes that did not intersect the floor, had the floor defined by the RC drill holes. All the
RC drill
holes intersected the floor or the base. The TSF material was classified as a Measured Mineral
Resource.
Technical Report Summary of the material Tailings Storage
Facilities
117
11.12.5
Mineral Resource Statement
The Mineral Resource in Table 11.20 to Table 11.21
is 100% attributable to DRDGOLD.
Table 11.20:
Ergo Mineral Resource Estimates (Inclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
7L15
Measured
17,646
0.26
147,506
17,646
0.26
147,506
Rooikraal
Measured
56,763
0.26
474,493
56,763
0.26
474,493
Sub-total Measured
Mineral Resources
74,409
0.26
621,999
74,409
0.26
621,999
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
74,409
0.26
621,999
74,409
0.26
621,999
Inferred Mineral
Resources
-
-
-
-
-
-
Total Mineral Resource
74,409
0.26
621,999
74,409
0.26
621,999
Source: The RVN Group, 2022
Table 11.21:
Ergo Mineral Resource Estimates (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
7L15
Measured
-
-
-
-
-
-
Rooikraal
Measured
-
-
-
-
-
-
Sub-total Measured
Mineral Resources
-
-
-
-
-
-
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
-
-
-
-
-
-
Inferred Mineral
Resources
-
-
-
-
-
-
Total Mineral Resource
-
-
-
-
-
-
Source: The RVN Group, 2022
11.12.6
Mineral Resource Changes
There was
no change
in the
Mineral Resource
as no
mining or
additional deposition
was done
on the
Rooikraal and 7L15 TSFs.
Technical Report Summary of the material Tailings Storage
Facilities
118
11.12.7
Mineral Resource Risks and Uncertainty
The QP classified
the overall Mineral
Resource risk for
both the Rooikraal
and 7L15 TSFs
as medium due
to the low-grade margin, gold price, recovery and
working costs.
In the opinion of the QP, no further technical work is required as the drilling
program provided sufficient
data to define continuity.
11.13
Marievale Complex
11.13.1
Exploratory Data Analysis
Exploratory data
analysis
was done
on raw
and composited
gold
data (Figure
11.41 to
Figure 11.48).
Data
was
analyzed
as
raw,
capped
and
composites.
There
was
no
material
changed
between
the
data sets. The data sets distribution is symmetrical.
Based on
the investigation,
cutting or
capping of
the extreme
values was
considered. Lower
extreme
grades were noted and visualized in 3D space. They were
considered part of the population:
●
7L4: capping was
applied at 0.45g/t Au.
All gold grades
greater than 0.45g/t were
set as 0.45g/t;
●
7L5: no capping was applied as no outliers were noted;
●
7L6: no capping was applied as no outliers were noted;
and
●
7L7: capping was applied at 0.70g/t Au to minimize the impact
of extremely high values.
A study on domaining was conducted.
The TSFs were not domained laterally or vertically;
however, the
QP noted
the
vertical
stratification.
This stratification
aided
in
defining
the search
volume (estimation
parameter) in a vertical direction.
The gold distributions are symmetrical and the variability
is low, typical for a TSF.
Technical Report Summary of the material Tailings Storage
Facilities
119
Figure 11.41:
7L4: Distribution of Capped Raw Gold Data
Source: The RVN Group, 2022
Figure 11.42:
Distribution of Composited Raw Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
120
Figure 11.43:
7L5: Distribution of Raw Gold Data
Source: The RVN Group, 2022
Figure 11.44:
7L5: Distribution of Composited Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
121
Figure 11.45:
7L6: Distribution of Raw Gold Data
Source: The RVN Group, 2022
Figure 11.46: 7L6:
Distribution of Composited Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
122
Figure 11.47:
7L7: Distribution of Raw Capped Gold Data
Source: The RVN Group, 2022
Figure 11.48:
7L7: Distribution of Composited Capped Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
123
11.13.2
Modelling and Estimation Parameters
The height of the original dump benches
is approximately 5m to 6m. The
parent block sizes selected to
estimate the deposit
approximates half
the drill
hole spacing and
corresponds to
the bench
height or
multiple thereof. Sub-blocking was allowed for good volume
definition.
The sample search parameters are supplied in Table
11.22.
Table 11.22:
Search Parameters
Domain
Estimation Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Samples Per
Drill Hole
X
(m)
Y
(m)
Z
(m)
Slime
1
400
400
6
3
10
2
2
800
800
12
3
10
2
3
1,200
1,200
18
3
10
2
Source: The RVN Group, 2022
11.13.3
Technical and Economic Factors
The
technical
and
financial
studies
completed
for
the
Marievale
Complex
were
at
the
preliminary
feasibility
study
(PFS)
level
of
accuracy,
(i.e.,
+/-25%)
as
presented
in
Item
13
to
Item
19.
The
QP
concluded that there are reasonable prospects
for economic extraction.
11.13.4
Mineral Resource Classification Criteria
A
list
of
the
criteria
used
to
classify
the
Mineral
Resources
is
given
in
Table
11.23.
Applying
these
confidence
levels,
Mineral
Resource
classification
codes
were
assigned
to
the
block
model.
A
low
confidence
in
one of
the
listed
items will
mean
classification
is downgraded
to Inferred,
a moderate
confidence in at least one item will mean a property
is Indicated while all highs mean the property is
in
the Measured Mineral Resource category.
Technical Report Summary of the material Tailings Storage
Facilities
124
Table 11.23:
Confidence Levels for Key Criteria for Mineral Resource
Classification
Items
Discussion
Confidence
Drilling Techniques
Auger drilling technique to international standards
High
Logging
Detailed logging throughout
High
Sub-sampling Techniques
and Sample Preparation
Material has previously been processed and quartering was
applied
High
Quality of Assay Data
Available data is of robust quality however there is a relatively
high variability in the lowest grade assays
High
Verification of Sampling
and Assaying
A comprehensive QC program implemented during exploration
High
Location of Sampling Points
Survey of all collars and TSFs surfaces
High
Data Density and
Distribution
Data points were well spread
High
Database Integrity
Errors identified and rectified
High
Geological Interpretation
Geometry is known accurately
High
Bulk Density
A mean density of 1.42t/m
3
was considered reasonable
High
Mineralization Type
Mineralization is well known from processing
High
Estimation
and
Modelling
Techniques
NN, and Inverse Distance
High
Source: The RVN Group, 2022
The
material
was
classified
as
a
Measured
Mineral
Resource
as
drill
hole
spacing
was
approximately
100m-by-100m.
No
Indicated
or
Inferred
Mineral
Resources
were
declared
as
the
geological
confidence derived from
exploration, test work and
Mineral Resource estimation
work was conclusive,
and the defined Mineral Resource can be used for mine
planning studies.
11.13.5
Mineral Resource Statement
The Mineral Resource Estimates
are stated as both an
inclusive and exclusive of Mineral Reserve
(Table
11.24 to Table 11.25).
Table 11.24:
Marievale Mineral Resource Estimates (Inclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
7L4
Measured
17,590
0.34
192 281
17,590
0.34
192,281
7L5
Measured
6,980
0.29
65 080
6,980
0.29
65,080
7L6
Measured
12,760
0.26
106 663
12,760
0.26
106,663
7L7
Measured
16,784
0.32
172 678
16,784
0.32
172,678
Sub-total Measured
Mineral Resources
54,114
0.31
536,701
54,114
0.31
536,701
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
54,114
0.31
536,701
54,114
0.31
536,701
Inferred Mineral
Resources
-
-
-
-
-
-
Total Mineral Resource
54,114
0.31
536,701
54,114
0.31
536,701
Technical Report Summary of the material Tailings Storage
Facilities
125
Source: The RVN Group, 2022
Table 11.25:
Marievale Resource Estimates (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as at 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
7L4
Measured
-
-
-
-
-
-
7L5
Measured
-
-
-
-
-
-
7L6
Measured
-
-
-
-
-
-
7L7
Measured
-
-
-
-
-
-
Measured Mineral
Resources
-
-
-
-
-
-
Indicated Mineral Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral Resources
-
-
-
-
-
-
Inferred Mineral Resources
-
-
-
-
-
-
Total Mineral Resources
-
-
-
-
-
-
Source: The RVN Group, 2022
Notes:
1.
Mineral Resources are not Mineral Reserves.
2.
Mineral Resources are reported exclusive of Mineral Reserves.
3.
Mineral Resources have been reported in accordance
with Subpart 1300 of Regulation S-K.
4.
Mineral Resources were
estimated using the USD1,823/oz,
ZAR15.60ZAR/USD and ZAR914,294ZAR/kg financial parameters
and recoveries
in Item 11.13.3.
5.
A troy ounce = 31.1034768g
6.
The quantities and grades have been rounded to two decimal
places;
therefore, minor computational errors may occur.
11.13.6
Mineral Resource Changes
There was
no change
in Mineral
Resource as no
drilling, mining,
or additional
deposition was
done on
Marievale Complex since the latest estimate.
11.13.7
Mineral Resource Risks and Uncertainty
The
QP’s
opinion
is
that
the
overall
grade
and
tonnage
estimates
are
reasonable
for
mine
planning
based
on
the
drill
hole
data
and
assay
statistics.
This
presents
a
low
risk
for
preliminary
feasibility
or
feasibility
mine
planning
work,
as
only
Mineral
Resources
with
the
highest
level
of
geoscientific
knowledge are included in an economic assessment.
The gold price fluctuations present the main risk to the declared
Mineral Resource.
Risks
of
grade
and
continuity
of
mineralization
were
mitigated
through
the
closely
spaced
drilling,
validation
procedures,
metallurgical
testing,
advanced
statistical
analyses
and
the
use
of
robust
geological modelling techniques.
The QP classified the overall Mineral Resource risk as low to medium. In the opinion of the QP, no further
technical work is required as the drilling program provided
enough data to define continuity.
Technical Report Summary of the material Tailings Storage
Facilities
126
11.14
Grootvlei Complex
11.14.1
Exploratory Data Analysis
Analysis
of
data
from
different
campaigns
was
completed
to
check
compatibility.
Tools used
for
this
were
box
plots,
histograms,
PP
and
QQ
plots,
and
ANOVA
table.
Datasets
from
different
campaigns
were then combined.
Based on
the high-grade
cap investigations,
high-grade caps
were selected
and applied
to the
raw
dataset. A little/insignificant reduction in the available
metal was noted.
●
6L16: gold grades were capped at 0.70g/t;
●
6L17: gold grades were capped at 0.69g/t;
and
●
6L17A: gold grades were capped at 0.65g/t.
Capping
was only
applied to
raw data
and its
impact on
the mean
was immaterial
for the
6L17 and
6L17A TSFs. One
sample with 16.10g/t
skewed the results
for the 6L16
TSF. Additional infill
drilling is
required
on 6L16
TSF to
further
test
the
robustness
of
the
high
grade
intersects,
which,
if
confirmed
by
the
infill
drilling, may support a less aggressive capping strategy.
Figure 11.54
to Figure
11.49 presents the
basic statistics data
for 6L16,
6L17 and
6L17A. Data
was analyzed
as raw, capped and composites. There was
no material changed between the data sets. The
data sets
show positively skewed distribution.
Technical Report Summary of the material Tailings Storage
Facilities
127
Figure 11.49:
6L16: Distribution of Raw Capped Gold Data
Source: The RVN Group, 2022
Figure 11.50:
6L16: Distribution of Composited Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
128
Figure 11.51:
6L17: Distribution of Raw Capped Gold Data
Source: The RVN Group, 2022
Figure 11.52:
6L17: Distribution of Composited Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
129
Figure 11.53:
6L17A: Distribution of Raw Capped Gold Data
Source: The RVN Group, 2022
Figure 11.54:
6L17A: Distribution of Composited Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
130
11.14.2
Modelling and Estimation Parameters
The parent
block size for
the TSF
was largely based
on the
average drill spacing
and sample compositing
interval.
The
height
of
the
original
dump
benches
is
approximately
5m
to
6m.
The
parent
block
sizes
selected to estimate the deposit approximates the drill hole spacing for the 6L17 and 6L17 TSFs, half the
drill hole spacing
for 6L16
TSFs and
maps the
bench height. Sub-blocking
was allowed for
a good volume
definition.
The sample search parameters are supplied in Table
11.26.
Table 11.26:
Search Parameters: Inverse Distance Estimation
Method
Domain
Estimation Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
X
(m)
Y
(m)
Z
(m)
Grootvlei
1
400
400
10
5
20
2
800
800
20
5
20
3
1,200
1,200
30
5
20
Source: The RVN Group, 2022
11.14.3
Technical and Economic Factors
The Mineral
Resource Estimates
for the 6L16,
6L17 and
6L17A TSFs
were declared
considering the
initial
assessment completed.
The Grootvlei
TSFs are
not included
in the
LoM plan.
The cut-off
grade details
are presented in Table 11.2.
11.14.3.1
Site Infrastructure
Roads:
Access
to
the
Grootvlei
Complex
is
via
the
N17
highway
and
a
network
of
well-maintained
paved road system. The operation is accessed via
gravel roads.
Power:
Power requirements
are primarily
for the operation
of pumps
and site
offices. Power
is sourced
from the national supplier, Eskom. There is a power
supply near the TSFs.
Site
Offices
and
Workshop:
Site
offices
are
typically
established
by
mining
contractors
as
part
of
the
mining contract.
Workshops for
the maintenanc
e
of roads,
pumps and
pipelines
is based
at the
Ergo
processing plant and no additional infrastructure is required.
The Grootvlei
Complex is
situated in
the City
of Ekurhuleni,
so other
specialized services could
be sourced
from the private workshops.
Pumps
and
Pipelines:
Before
mining
can
start,
the
pump
station
and
pipeline
to
the
Ergo
processing
plant in Brakpan will be required to be completed. As other TSFs in the same vicinity are in the LoM plan
with a detailed pipeline plan, it is the QP’s view
that a shorter (less than 5km) pipeline will be required to
connect the Grootvlei TSFs to the other planned pipeline network (for
Daggafontein TSF in the LoM plan
done at PFS level).
Tailings
Deposition
Site:
Ergo
has
sufficient
tailings
deposition
capacity
at
their
Brakpan/Withok
TSF
to
accommodate all
material from
Grootvlei Complex
,
in addition
to the
tons in
the LoM
plan provided
regulatory approval
for the
Brakpan/Withok TSF
final design
is obtained.
See Item
15.7 and
Item 19.3.2
for more information on the deposition plans.
Technical Report Summary of the material Tailings Storage
Facilities
131
11.14.3.2
Mine Design and Planning
Mine design
and planning will
be similar to
the one
in Item
13.1.1. A
production rate of
600ktpm (200ktpm
per TSF) is assumed due to the pipeline capacity as the TSFs could be mined together
with others in the
same vicinity.
11.14.3.3
Processing Plant
The Grootvlei Complex material could be processed at
the Ergo processing plant (see Item 10.5.).
11.14.3.4
Environmental Compliance and Permitting
Ergo’s Prospecting Rights covering the Grootvlei Complex
are presented in Item 3.3.
Ergo complies with all environmental and
social responsibilities as required by the
MPRDA, as amended.
No known environmental
issues were identified during
the site visit and
documentation review. There
is
an EMP approved
by the DMRE.
There are no
exclusions of material
or area due
to Environmental,
Social
and Governance considerations.
As discussed in Item 3.6, there is a competing ownership
claim over the Grootvlei Complex.
11.14.3.5
Initial Assessment Results
The QP’s opinion is that
there is a reasonable prospect
for economic extraction based on
the total mix
of technical and economic factors discussed.
11.14.4
Mineral Resource Classification Criteria
A
list
of
the
criteria
used
to
classify
the
Mineral
Resources,
in
addition
to
the
statistical
parameters,
is
given
in
Table
11.27.
Applying
these
confidence
levels,
Mineral
Resource
classification
codes
were
assigned
to
the
block
model.
A
low
confidence
in
one
of
the
listed
items
will
mean
classification
is
downgraded to Inferred, a moderate confidence in at least one item will mean a property is Indicated
while all highs mean the property is in the Measured Mineral
Resource category.
Technical Report Summary of the material Tailings Storage
Facilities
132
Table 11.27:
Confidence Levels for Key Criteria for Mineral Resource
Classification
Items
Discussion
Confidence
Drilling Techniques
Auger and RC drilling technique to international standards
High
Logging
Detailed logging throughout
High
Drill Sample Recovery
The sample recovery was considered satisfactory and was
acceptable for Mineral Resource estimation
High
Sub-sampling
Techniques and
Sample Preparation
Material has previously been processed and quartering was applied
High
Quality of Assay Data
Available data is of robust quality however there is a relatively high
variability in the lowest grade assays
High
Verification of
Sampling and
Assaying
Full QC program implemented during exploration
High
Location of Sampling
Points
Survey of all collars and TSFs surfaces
High
Data Density and
Distribution
Data points were well spread, though widely spaced. Approximately
100m-by-100m spacing was followed for 6L17 and 6L17A TSFs. 6L16 TSF
has an average drill hole spacing of 200m-by-200m
High (6L17
and 6L17A)
Moderate for
6L16
Database Integrity
Errors identified and rectified
High
Geological
Interpretation
Geometry is known accurately
High
Bulk Density
A mean density of 1.42t/m
3
was considered reasonable
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and
Modelling
Techniques
NN and Inverse Distance
High
Source: The RVN Group, 2022
The drill
hole
spacing
was
approximately
100-by-100m
on the
6L17
and
6L17A
TSFs. With
this
grid,
the
grade,
floor
elevation
and
TSF
geometry
were
estimated
with
sufficient
confidence
to
allow
the
application
of
modifying
factors
in
sufficient
detail
to
support
mine
planning
and
evaluation
of
the
economic viability of the
TSFs. The 6L17 and
6L17A TSFs were
classified in the Measured
Mineral Resource
category. The 6L16
TSF was declared
as Indicated Mineral
Resource, as the
drill space is
too wide (200m-
by-200m).
The
data
or
supporting
information
is
derived
from
adequately
detailed
and
reliable
exploration,
sampling
and testing
and is
sufficient to
assume
geological
and grade
or quality
continuity between
the points of observation.
11.14.5
Mineral Resource Statement
The Mineral
Resource Estimates for
the Grootvlei
Complex is
presented in
Table 11.28.
No Mineral
Reserve
was declared on the Grootvlei TSFs, so exclusive and
inclusive are equal.
Technical Report Summary of the material Tailings Storage
Facilities
133
Table 11.28:
Grootvlei Complex Mineral Resource Estimates (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
6L17
Measured
49,320
0.26
412,275
49,320
0.26
412,275
6L17A
Measured
16,716
0.26
140,807
16,716
0.26
140,807
Sub-total Measured
Mineral Resources
66,036
0.26
553,082
66,036
0.26
553,082
6L16
Indicated
41,619
0.26
347,901
41,619
0.26
347,901
Sub-total Indicated
Mineral Resources
41,619
0.26
347,901
41,619
0.26
347,901
Sub-total Measured and
Indicated Mineral
Resources
107,655
0.26
900,984
107,655
0.26
900,984
Inferred Mineral
Resources
-
-
-
-
-
-
Total Mineral Resource
107,655
0.26
900,984
107,655
0.26
900,984
Source: The RVN Group, 2022
11.14.6
Mineral Resource Changes
There was no
change in Mineral Resource
as no additional drilling,
mining,
additional deposition or
study
was done on the Grootvlei Complex.
11.14.7
Mineral Resource Risks and Uncertainty
The renewal
of the Prospecting
Right for the
Grootvlei Complex
is a risk.
The application
to renew
was
launched in 2019 and Ergo is awaiting the granting of the Prospecting Permit from the DMRE. This report
has considered section 18(5) of the MPRDA, as ame
nded:
“
A prospecting
right in respect
of which an
application for
renewal has
been lodged
shall despite
its
expiry date remain in force until such time as such application
has been granted or refused.
”
There is an ownership claim as detailed in Item 3.6.
The QP classified the overall Mineral Resource
risk as high.
In the opinion of the QP, no further technical
work is required as the drilling program provided sufficient
data to define continuity.
11.15
5A10/5L27 Sand Dumps
11.15.1
Exploratory Data Analysis
Exploratory data
analysis was
performed on
gold grades.
No capping
was applied
as data
shows no
extreme values.
Samples
were composited
to 6m
interval.
The mean
did not
change
materially
after
compositing into 6m interval.
Figure 11.55 and Figure 11.56 present the basic statistical data
for the 5A10/5L27 sand dumps.
Data was
analysed as raw, capped and composites. There
was no material changed between the
data sets. The
data sets show positively skewed distribution.
Technical Report Summary of the material Tailings Storage
Facilities
134
Figure 11.55:
5A10/5l27:
Distribution of Raw Gold Data
Source: The RVN Group, 2022
Figure 11.56:
5A10/5l27:
Distribution of Composited Gold Data
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
135
11.15.2
Modelling and Estimation Parameters
The parent
block size
for the
sand dumps
was largely
based on
the average
drill spacing
and sample
compositing
interval.
The
height
of
the
original
sand
dump
benches
is
approximately
5m
to
6m.
The
parent block
sizes selected
to estimate
the deposit
approximates the
drill hole
spacing and
maps the
bench height. Sub-blocking was allowed for a good
volume definition.
The sample search parameters are supplied in
Table
11.29
.
Table
11.29:
Search Parameters: Inverse Distance Estimation Method
Domain
Estimation Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
X
(m)
Y
(m)
Z
(m)
5A10/5l27
100
100
50
4
10
100
200
200
100
4
10
200
300
200
200
4
10
300
Source: The RVN Group, 2022
11.15.3
Technical and Economic Factors
The QP
declared the
Mineral Resource
estimate for
the 5A10/5L27
sand dumps
considering technical
and economic studies in Item 13 to Item 19.
11.15.4
Mineral Resource Classification Criteria
A list of the
criteria used to classify the
Mineral Resources in addition to
the statistical parameters is given
in
Table
11.30.
Applying
these
confidence
levels,
the
Mineral
Resource
classification
codes
were
assigned to the block model.
Technical Report Summary of the material Tailings Storage
Facilities
136
Table 11.30:
Confidence Levels for Key Criteria for Mineral Resource
Classification
Items
Discussion
Confidence
Drilling Techniques
Auger and drilling technique to international standards
High
Logging
Detailed logging throughout
High
Drill Sample Recovery
The sample recovery was considered satisfactory and was
acceptable for Mineral Resource estimation
High
Sub-sampling Techniques
and Sample Preparation
Material has previously been processed and quartering was
applied
High
Quality of Assay Data
Available data is of robust quality however there is a relatively
high variability in the lowest grade assays
High
Verification of Sampling
and Assaying
Full QC program implemented during exploration
High
Location of Sampling Points
Survey of all collars and TSFs surfaces
High
Data Density and
Distribution
Data points were well spread, though widely spaced.
Approximately 50m-by-100m spacing was followed. Where drill
holes did not intersect the base, holes were completed on the
edge
High
Database Integrity
Errors identified and rectified
High
Geological Interpretation
Geometry is known accurately
High
Bulk Density
A mean density of 1.42t/m
3
was considered reasonable
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and Modelling
Techniques
NN and Inverse Distance
High
Source: The RVN Group, 2022
The drill hole spacing enabled the QP to define gold grades, floor elevation and sand dump geometry.
This
provide
the
QP
conclusive
confidence
to
allow
the
application
of
modifying
factors
in
sufficient
detail to support mine planning
and evaluation of the economic
viability of the sand
dumps. The sand
dumps were
classified
as
Measured
Mineral
Resources.
The data
or
supporting
information
is derived
from the adequately detailed and reliable exploration, sampling and testing and is sufficient to assume
geological
and
grade
or
quality
continuity
between
points
of
observation.
The
resource
model
and
production
data
reconciled
well
with
less
than
a
1%
grade
difference.
This
was
also
considered
in
classifying the 5A10/5L27 sand dumps as Measured Mineral
Resources.
Technical Report Summary of the material Tailings Storage
Facilities
137
11.15.5
Mineral Resource Statement
The Mineral
Resource
estimates
for
the
5A10/5L27
sand
dumps
are
presented
in
Table
11.28
to
Table
11.32.
Table 11.31:
5A10/5L27 Mineral Resource Estimates (Inclusive)
TSF
Mineral
Resource
Category
Mineral Resources as 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
5L27 (East)
Measured
5,965
0.48
92,054
3,979
0.49
60,467
5L27 (North)
Measured
4,288
0.28
38,601
4,288
0.28
38,601
5A10
Measured
2,117
0.61
41,519
1,595
0.61
31,285
Sub-total Measured Mineral
Resources
12,370
0.43
172,174
9,862
0.42
128,075
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
12,370
0.43
172,174
9,862
0.42
128,075
Inferred Mineral Resources
-
-
-
-
-
-
Total Mineral Resource
12,370
0.43
172,174
9,862
0.42
128,075
Source: The RVN Group, 2022
Table 11.32:
5A10/5L27 Mineral Resource Estimates (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
5L27
Measured
-
-
-
-
-
-
5A10
Measured
-
-
-
-
-
-
Sub-total Measured Mineral
Resources
-
-
-
-
-
-
Indicated Mineral
Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral
Resources
-
-
-
-
-
-
Inferred Mineral Resources
-
-
-
-
-
-
Total Mineral Resource
-
-
-
-
-
-
Source: The RVN Group, 2022
11.15.6
Mineral Resource Changes
Mining took place on the
5A10 sand dump reclaiming
808kt at 0.61g/t Au in the
last financial year. The
mined and modelled tonnage and grades reconciled
well.
Technical Report Summary of the material Tailings Storage
Facilities
138
11.15.7
Mineral Resource Risks and Uncertainty
The
QP’s
opinion
is
that
the
overall
grade
and
tonnage
estimates
are
reasonable
for
mine
planning
based on the borehole
data and assay statistics.
Production data reconciled well with
the block model.
The
gold
price
fluctuations
and
lower
grades
of
sand
material
present
the
main
risk
to
the
declared
Mineral Resource.
The QP classified the overall Mineral Resource risk as low to medium. In the opinion of the QP, no further
technical work is required as the drilling program provided
enough data to define continuity.
11.16
Daggafontein TSF
11.16.1
Exploratory Data Analysis
The QP tested if there
was a material difference
in the gold grades from
the various drilling campaigns
to ascertain if the datasets
from the different campaigns
were compatible. Figure 11.57
shows the box
plots
of
the
different
campaigns.
The
difference
was
considered
minor
by
the
QP.
The
2017
drilling
campaign reported
slightly higher
grades. This
campaign,
however only
comprised two
drill holes
(on
either side of the TSF
–
east and west). Analysis of variance and a Tukey (Honest Significant Differences)
HSD plot showed
that there is
a difference in
sample means
between 2017
and the other
campaigns.
The QP
investigated the
differences and
concluded that
the difference
is due
to the
amount of
data
per campaign and spatial distribution
of the data point.
Accordingly, the QP concluded that
data from
the campaigns could be combined.
Figure 11.57:
Boxplots for the Different Drilling Campaigns
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
139
The
drill
hole
individual
sample
gold
grades
are
positively
skewed.
The
mean
of
the
gold
grades
is
0.24g/t.
Based
on
the
statistical
investigation,
cutting
or
capping
of
the
extreme
values
was
not
considered
(Figure 11.58). Lower
extreme grades were
noted and visualized in
3D space. They
were considered part
of the population.
Figure 11.58:
Log Probability Plot
Source: The RVN Group, 2022
A study on domaining
was conducted. This was
done through analysis
of zones based on
TSF material,
color and
spatial grade analysis.
The TSF
was not
domained laterally or
vertically, however, the
QP noted
the vertical stratification. This stratification aided in
defining the search volume in the vertical direction.
No capping was applied.
11.16.2
Modelling and Estimation Parameters
The parent
block size for
the TSF
was largely based
on the
average drill spacing
and sample compositing
interval.
Technical Report Summary of the material Tailings Storage
Facilities
140
The sample search parameters are supplied in Table
11.33.
Table 11.33:
Search Parameters
Domain
Estimation Pass
Search Distance
Minimum
Number of
Composites
Maximum
Number of
Composites
Maximum
Number of
Samples Per
Drill Hole
X
(m)
Y
(m)
Z
(m)
Slime
1
500
500
6
5
20
4
2
1,000
1,000
12
5
20
4
3
1,500
1,500
18
5
20
4
Source: The RVN Group, 2022
11.16.3
Technical and Economic Factors
The QP
declared the
Mineral Resource
estimates for
the Daggafontein
TSF considering
technical and
economic studies in Item 13 to Item 19.
The Daggafontein
TSF's average
gold grade
is 0.24g/t,
which is
above the
cut-off grade
presented
in
Table 11.2.
Selective mining
of the
TSF is
not practiced
by Ergo,
therefore a
cut-off is
not a
block level
but it is for the entire TSF. If a TSF mean grade is above cut
-off, it is considered for the Mineral Resource.
The QP’s opinion is that
there is a reasonable prospect
for economic extraction based on
the total mix
of technical and economic
factors discussed.
11.16.4
Mineral Resource Classification Criteria
A list of
the criteria used
to classify the
Mineral Resources is
given in Table
11.34 below. Applying
these
confidence levels, Mineral Resource classification codes
were assigned to the block model.
Table
11.34:
Confidence Levels for Key Criteria for Mineral Resource Classification
Items
Discussion
Confidence
Drilling Techniques
RC drilling technique to international standards
High
Logging
Detailed logging throughout
High
Sub-sampling Techniques and
Sample Preparation
Material has previously been processed and quartering
was applied
High
Quality of Assay Data
Available data is of robust quality however there is a
relatively high variability in the lowest grade assays
High
Verification of Sampling and Assaying
Full QC program implemented during exploration
High
Location of Sampling Points
Survey of all collars and TSFs surfaces
High
Data Density and Distribution
Data points were well spread. No drilling under water
Moderate
(low for
underwater
material)
Database Integrity
Errors identified and rectified
High
Geological Interpretation
Geometry is known accurately
High
Bulk Density
A mean density of 1.42t/m
3
was considered reasonable
High
Mineralization Type
Mineralization is well known from processing
High
Estimation and Modelling Techniques
NN, Inverse Distance and Ordinary Kriging
High
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
141
Where drill hole spacing is less than 250m,
the material was classified as an Indicated
Mineral Resource
(Figure 11.59). An
Inferred Mineral Resource
was defined for
the area under
water where drilling
could
not be done and grades were estimated on the second
pass i.e., up to 1,000m drilling space.
Figure 11.59:
Mineral Resource Classification
Source: The RVN Group, 2022
11.16.5
Mineral Resource Statement
The Mineral Resource is stated in Table 11.35 and
Table 11.36.
Table 11.35:
Daggafontein TSF Mineral Resource Estimate (Inclusive)
TSF
Mineral
Resource
Category
Mineral Resources as 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
Measured Mineral Resources
-
-
-
-
-
-
Indicated Mineral Resources
192,793
0.24
1,487,625
192,793
0.24
1,487,625
Sub-total Measured and
Indicated Mineral Resources
192,793
0.24
1,487,625
192,793
0.24
1,487,625
Inferred Mineral Resources
21,318
0.24
164,494
21,318
0.24
164,494
Total Mineral Resources
214,111
0.24
1,652,119
214,111
0.24
1,652,119
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
142
Table 11.36:
Daggafontein TSF Mineral Resource Estimate (Exclusive)
TSF
Mineral
Resource
Category
Mineral Resources as 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
Measured Mineral Resources
-
-
-
-
-
-
Indicated Mineral Resources
-
-
-
-
-
-
Sub-total Measured and
Indicated Mineral Resources
-
-
-
-
-
-
Inferred Mineral Resources
21,318
0.24
164,494
21,318
0.24
164,494
Total Mineral Resources
21,318
0.24
164,494
21,318
0.24
164,494
Source: The RVN Group, 2022
11.16.6
Mineral Resource Changes
There was
no change
in the
Mineral Resource
from June
2021 to
June 2022
as no additional
drilling or
studies were completed on the Daggafontein TSF.
11.16.7
Mineral Resource Risks and Uncertainty
The
QP’s
opinion
is
that
the
overall
grade
and
tonnage
estimates
are
reasonable
for
mine
planning
based on the drill hole data
and assay statistics. The Inferred
portion of the Mineral Resource could
not
be
sufficiently
drilled
as
this
portion
of
the
TSF
remains
saturated
and
its
estimation
was
based
on
extrapolation.
This presents
a low
risk
for preliminary
feasibility
or feasibility
mine
planning
work, as
no
Inferred Resource was included in an economic assessment.
The gold price fluctuations and lower grades present
the main risk to the declared Mineral Resource.
Risks
of
grade
and
continuity
of
mineralization
were
mitigated
through
infill
drilling,
validation
procedures,
metallurgical
testing,
advanced
statistical
analyses
and
the
use
of
robust
geological
modelling techniques.
The QP classified the overall Mineral Resource risk as low to medium. In the opinion of the QP, no further
technical work is
required as the
drilling program provided sufficient
data to define
continuity. No drilling
in the waterlogged area is recommended.
Technical Report Summary of the material Tailings Storage
Facilities
143
11.17
Summary Mineral Resource Estimates
Table 11.37
presents the
summary of the
Mineral Resource
estimates (inclusive)
for the 18
TSFs and
the
one sand
dump. The
Mineral Resource
estimates are
reported as
inclusive of
the Mineral
Reserve and
the reference point is in situ.
Table 11.37:
Inclusive Mineral Resources of the 19 Material Properties
as at 30 June 2022
Complex
TSF/Sand Dump
Category
Mineral Resources as at 30 June
2021 (Inclusive)
Mineral Resources as at 30 June
2022 (Inclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
City Deep
4L3
Measured
13,134
0.32
135,126
13,134
0.32
135,126
4L4
Measured
4,738
0.32
48,746
4,738
0.32
48,746
4L6
Measured
2,410
0.31
24,020
2,410
0.31
24,020
Knights
4L14
Measured
6,638
0.29
61,891
6,638
0.29
60,824
4L50
Measured
6,756
0.26
56,475
3,418
0.26
27,216
Ergo
7L15
Measured
17,646
0.26
147,506
17,646
0.26
147,506
Rooikraal
Measured
56,763
0.26
474,493
56,763
0.26
474,493
Marievale
7L4
Measured
17,590
0.34
192,281
17,590
0.34
192,281
7L5
Measured
6,980
0.29
65,080
6,980
0.29
65,080
7L6
Measured
12,760
0.26
106,663
12,760
0.26
106,663
7L7
Measured
16,784
0.32
172,678
16,784
0.32
172,678
Grootvlei
6L17
Measured
49,320
0.26
412,275
49,320
0.26
412,275
6L17A
Measured
16,716
0.26
140,807
16,716
0.26
139,732
5A10/5L27
5A10/5L27
Measured
11,985
0.43
164,623
9,862
0.42
128,075
Sub-total Measured Mineral Resources
240,220
0.29
2,202,664
234,759
0.28
2,134,715
Grootvlei
6L16
Indicated
41,619
0.26
347,901
41,619
0.26
347,901
Daggafontein
Daggafontein
Indicated
192,793
0.24
1,487,625
192,793
0.24
1,487,625
Crown
Mooifontein
(3L7)
Indicated
67,559
0.23
499,577
67,559
0.23
499,577
GMTS (3L8)
Indicated
107,450
0.25
863,649
107,450
0.25
863,649
Diepkloof (3L5)
Indicated
97,988
0.23
724,589
97,988
0.23
724,589
Sub-total Indicated Mineral Resources
507,409
0.24
3,923,341
507,409
0.24
3,923,341
Sub-total Measured and Indicated Mineral
Resources
747,629
0.25
6,126,005
742,168
0.25
6,058,056
Daggafontein
Daggafontein
Inferred
21,318
0.24
164,494
21,318
0.24
164,494
Sub-total Inferred Mineral Resources
21,318
0.24
164,494
21,318
0.24
164,494
Total Material Mineral Resources
768,947
0.25
6,290,499
763,486
0.25
6,222,550
Source: The RVN Group, 2022
Notes:
i.
Mineral Resources are not Mineral Reserves.
ii.
Mineral Resources are reported inclusive of Mineral Reserves.
iii.
Mineral Resources have been reported in accordance with
Subpart 1300 of Regulation S-K
iv.
Mineral Resources
were estimated
using the
USD1,823/oz, ZAR15.60/USD,
ZAR914,294/kg financial
parameters and
recoveries
in Table 11.2
v.
A troy ounce = 31.1034768g
vi.
Quantities and grades were rounded to reflect the accuracy
of the estimates; and if any apparent errors are insignificant
Technical Report Summary of the material Tailings Storage
Facilities
144
Table 11.38 presents exclusive Mineral Resource estimates
for the material properties.
Table 11.38:
Exclusive Mineral Resources of the 19 Material Properties
as at 30 June 2022
Complex
TSF/Sand
Dump
Category
Mineral Resources as at 30 June
2021 (Exclusive)
Mineral Resources as at 30 June
2022 (Exclusive)
Tons
(kt)
Au
(g/t)
Content
(oz)
Tons
(kt)
Au
(g/t)
Content
(oz)
City Deep
4L3
Measured
-
-
-
-
-
-
4L4
Measured
-
-
-
-
-
-
4L6
Measured
-
-
-
-
-
-
Knights
4L14
Measured
-
-
-
-
-
-
4L50
Measured
-
-
-
-
-
-
Ergo
7L15
Measured
-
-
-
-
-
-
Rooikraal
Measured
-
-
-
-
-
-
Marievale
7L4
Measured
-
-
-
-
-
-
7L5
Measured
-
-
-
-
-
-
7L6
Measured
-
-
-
-
-
-
7L7
Measured
-
-
-
-
-
-
Grootvlei
6L17
Measured
-
-
-
49,320
0.26
412,275
6L17A
Measured
-
-
-
16,716
0.26
140,807
5A10/5L27
5A10/5L27
Measured
-
-
-
-
-
-
Sub-total Measured Mineral Resources
-
-
-
66,036
0.26
553,082
Grootvlei
6L16
Indicated
41,619
0.26
347,901
41,619
0.26
347,901
Daggafontein
Daggafontein
Indicated
192,793
0.24
1,487,625
-
-
-
Crown
Mooifontein
(3L7)
Indicated
67,559
0.23
499,577
67,559
0.23
499,577
GMTS (3L8)
Indicated
107,450
0.25
863,649
107,450
0.25
863,649
Diepkloof
(3L5)
Indicated
97,988
0.23
724,589
97,988
0.23
724,589
Sub-total Indicated Mineral Resources
507,409
0.24
3,923,342
314,616
0.24
2,435,716
Sub-total Measured and Indicated Mineral
Resources
507,409
0.24
3,923,342
380,652
0.24
2,988,798
Daggafontein
Daggafontein
Inferred
21,318
0.24
164,494
21,318
0.24
164,494
Total Inferred Mineral Resources
21,318
0.24
164,494
21,318
0.24
164,494
Total Material Mineral Resource
528,727
0.24
4,087,835
401,970
0.24
3,153,292
Source: The RVN Group, 2022
Notes:
i.
Mineral Resources are not Mineral Reserves.
ii.
Mineral Resources are reported exclusive of Mineral Reserves.
iii.
Mineral Resources have been reported in accordance with
Subpart 1300 of Regulation S-K
iv.
Mineral Resources
were estimated
using the
USD1,823/oz, ZAR15.60/USD,
ZAR914,294/kg financial
parameters and
recoveries
in Table 11.2
v.
A troy ounce = 31.1034768g
vi.
Quantities and grades were rounded to reflect the accuracy
of the estimates; and if any apparent errors are insignificant
Technical Report Summary of the material Tailings Storage
Facilities
145
The total
Mineral
Resource
Estimates
for Ergo
are
presented
in
Table
11.39 and
Table
11.40. The
total
Mineral Resource consisted of 19 material properties
and 79 small TSFs and clean-up sites. The changes
in
Mineral
Resource
from
June
2021
to
June
2022
are
due
to
depletion
of
20.48Mt
at
0.33g/t Au and minor survey adjustments of 2.94Mt at 0.20g/t
Au as presented on Figure 11.60.
Table 11.39:
Ergo Inclusive Mineral Resources Statement as at 30 June
2022
Mineral Resources
Classification
Mineral Resources as at 30 June 2021
(Inclusive)
Mineral Resources as at 30 June 2022
(Inclusive)
Tons
(Mt)
Au
(g/t)
Content
(Moz)
Tons
(Mt)
Au
(g/t)
Content
(Moz)
Measured Mineral Resources
282.95
0.31
2.81
266.25
0.31
2.64
Indicated Mineral Resources
574.95
0.25
4.61
568.21
0.25
4.55
Sub-total Measured and
Indicated Mineral Resources
857.90
0.27
7.42
834.45
0.27
7.19
Inferred Mineral Resources
21.32
0.24
0.16
21.32
0.24
0.16
Total
Mineral Resources
879.22
0.27
7.58
855.77
0.27
7.35
Source: The RVN Group, 2022
Table
11.40:
Ergo Exclusive Mineral Resources Statement as at 30 June 2022
Mineral Resources
Classification
Mineral Resources as at 30 June 2021
(Exclusive)
Mineral Resources as at 30 June 2022
(Exclusive)
Tons
(Mt)
Au
(g/t)
Content
(Moz)
Tons
(Mt)
Au
(g/t)
Content
(Moz)
Measured Mineral Resources
-
-
-
66.04
0.26
0.55
Indicated Mineral Resources
574.95
0.25
4.61
375.41
0.25
3.02
Sub-total Measured and
Indicated Mineral Resources
574.95
0.25
4.61
441.45
0.25
3.57
Inferred Mineral Resources
21.32
0.24
0.16
21.32
0.24
0.16
Total
Mineral Resources
596.27
0.25
4.77
462.77
0.25
3.77
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
146
Figure 11.60:
Mineral Resource Reconciliation (Inclusive)
Source: The RVN Group, 2022
11.18
QP’s Opinion
In the QP’s opinion, all relevant technical and
economic factors that may likely affect the
prospects
of
economic
extraction,
were
adequately
considered
for
the
Mineral
Resources
reported.
The
QP
recommended no further work.
Technical Report Summary of the material Tailings Storage
Facilities
147
12
Mineral Reserve Estimates
This Item includes discussion and
comments on the conversion of
Mineral Resources to Mineral Reserves.
Specifically,
comments
are
provided
on
the
key
assumptions,
parameters
and
methods
(modifying
factors) used to estimate the 30 June 2022 Mineral Reserve.
Mineral Reserves
estimates are affected
by multiple
factors that change
over time. Fluctuations
in the
gold price, exchange rates, legislation in the operating country, other reporting jurisdictions and a wide
range
of
operating
conditions
may
affect
the
Mineral
Reserve
estimates.
Estimates
of
the
Mineral
Reserves should be considered best estimates at the
time of reporting.
The level
of the
study conducted
to support
the declaration of
the 30
June 2022
Mineral Reserve is
based
on a
mine plan
and design
conducted to
a PFS level
of accuracy
(i.e., +/-25%)
with a
maximum level
of contingency
of 15%.
Ergo utilizes
Measured and
Indicated Mineral
Resources incorporated
into the
LoM plan. No Inferred Mineral Resources have been
used in the LoM plan.
12.1
Grade Control and Reconciliation
The
Ergo
LoM
plan
and
schedule
for
the
individual
TSFs
is
based
on
3-D
geological
models,
which
provides
grade,
density,
and
volume
for
each
individual
block.
The
planning
department
takes
this
information and establishes a grade for the
proposed mining cut, typically in the order
of 15m. The mine
plan accounts for each block, resulting in a tonnage and
grade estimate for the entire mining block or
mining cut. The mining cut is then sequenced and scheduled.
Ergo
conducts
grade
and
tonnage
reconciliations
on
a
quarterly
basis
with
no
material
difference
between the planned and actual grade and tonnages
observed.
Table 12.1:
Reconciliation of RoM Head Grade (Au)
Year
Plan RoM Head
Grade
(g/t)
Actual RoM Head
Grade
(g/t)
Head Grade
Difference
(g/t)
Percentage
Difference
(%)
2019/2020
0.358
0.354
-0.003
-1.13%
2020/2021
0.354
0.363
0.009
2.54%
2021/2022
0.347
0.366
0.018
5.19%
Source: The RVN Group, 2022
Table 12.2:
Reconciliation of RoM Tonnage
Year
Measured Survey
Tonnage
(kt)
Processing Plant
Tonnage
(kt)
Tonnage
Difference
(kt)
Percentage
Difference
(%)
2019/2020
20 265
20 086
-179
-0.9%
2020/2021
22 884
22 949
66
0.7%
2021/2022
22 810
21 553
-1 527
-6.7%
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
148
The above results (Table
12.1 and Table 12.2)
indicate no material difference between
the planned and
actual grade and planned
and actual tonnages for years
2019/20 and 2020/21. However,
the 2021/22
reconciliation between planned and actual grade indicates a 5.2% increase in the gold grade (0.35g/t
versus 0.37g/t). Further, the
reconciliation showed a
6.7% decrease in the
planned tonnage during
the
same period. The higher grade
is associated with mining some
mineralized material not in the
mine plan
nor in the
Mineral Reserve,
which was
mined at a
higher grade than
anticipated. The
decrease in
the
tonnage was due to power issues at Knights
section. Knights was negatively affected by load shedding
(scheduled and
unscheduled power
cuts). Ergo
is addressing
this issue
by introducing
back-up power
generators and installing a
power cable from
City Deeps to
supply Knights with
power from Eskom
rather
than City
Power. The
supply
of Eskom
power will
result in
advised power
reduction
rather than
power
cuts without any warning, which was the case with City
Power.
12.2
Cut-off Grade Estimation
The cut-off
grade, for
the purposes
of the
Mineral Reserve
definition, is
defined as
the grade
at which
the value
of the
contained metal
in a
unit quantity
is equivalent
to the
cost of
its production,
i.e., the
breakeven grade.
Cut-off Grade
=
Total On-Mine Production Costs
(Metal Market Price
–
Off-Mine Costs) x Recovery
The gold price
and other operational inputs
are discussed in various
Items of this
Report; plant recoveries
are reviewed in Item
14,
Item 16 reports on
marketing and pricing, and operating costs
are commented
on in Item 18. The cut-off grade and
Mineral Reserve grades for the source
areas are provided in Table
12.3.
Note
that
due
to
the
nature
of
mining
TSFs,
the
cut-off
grade
is
not
based
on
a
block
value
or
individual sections of the
TSF but based on
the total TSF (i.e.,
if the entire TSF
grade is above the
cut-off
grade, the TSF will be mined.
Table 12.3:
Cut-off Grade and Mineral Reserve Grades
Source Area
Plant Recovery
(%)
Cut-off Au Grade
(g/t)
Mineral Reserve Au Grade
(g/t)
Ergo
40,87
0.24
0.28
Source: The RVN Group, 2022
Notes:
1.
The cut-off grade
provided above is
based on the
June 2022 LoM
plan and used
to validate the
30 June 2022
Mineral Resource and
Mineral Reserve estimation.
2.
Gold price ZAR914,294/kg (Item 16).
3.
On-mine cost ZAR90.86/t (Item 18).
4.
Off-mine cost ZAR0.00/t.
The various
modifying factors i.e.,
mining, metallurgical, processing,
infrastructure, economic, marketing,
legal,
environmental,
and governmental factors are discussed in Item 13 to
Item 19
Technical Report Summary of the material Tailings Storage
Facilities
149
12.3
Estimation and Modelling Techniques
Ergo reports its Mineral
Resources and Mineral
Reserves in accordance
with the Regulation S-K
1300. In
no case has Measured Mineral Resources been downgraded
to a Probable Mineral Reserve category.
Other than geological modelling, no other modelling or estimation techniques are used in the
selection
of Mineral Reserves. Selection for inclusion in the Mineral Reserves
is based on the average grade of the
TSF being above the required cut-off grade.
The following comments are relevant in the conversion
of Mineral Resources to Mineral Reserves:
●
there is no mining dilution, as each of the TSFs is to be
mined and processed in their entirety;
●
no allowance has been made for mining losses; and
●
a LoM
plan has
been generated
,
reviewed and
tested for
economic viability
in a
discounted
cash
flow
(DCF)
model.
Cognizance
has
been
taken
of
the
geotechnical
considerations
regarding the
safety of
the operation
and long-term
stability of
the TSF
walls, and
the working
considerations are
based on operational
practices as
provided by Fraser
Alexander (Proprietary)
Limited, a tailings design, management and mining company.
12.4
Mineral Reserve Classification Criteria
The
Mineral
Reserve
classification
of
Proven
and
Probable
is
a
function
of
the
Mineral
Resource
classification
with
due
considerations
of
the
minimum
criteria
for
the
“
modifying
factors
”
as
considered in
the S-K1300.
In no
case has
Measured Mineral Resources
been downgraded to
a Probable
Mineral Reserve Category.
Due to
the length
of approval
times for
the renewal
of permits,
some of
the Mineral
Reserves may
be
based on
permits (approvals)
still in
the process
of being
renewed. At
this time,
there is
no indication
that
these renewals
will
not be
granted
and
therefore
have
been
used
in
the
LoM plan
and
Mineral
Reserve statement.
12.5
Mineral Reserves Statement
Mineral
Reserves
are
based
on
the
30
June
2022,
LoM
plan
and
schedule.
The
Ergo
Mineral
Reserve
statement as at 30 June 2022 is provided in Table 12.4 along with the previous Mineral Reserves as at 30
June 2021.
The QP confirms that the Mineral Reserve statement presented in Table 12.4 is
disclosed in accordance
to the S-K1300 guidelines.
Technical Report Summary of the material Tailings Storage
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150
Table 12.4:
Ergo TSF Mineral Reserves Statement as at 30
June 2022
Mineral Reserve
Classification
Mineral Reserves as at 30 June 2021
Mineral Reserves as at 30 June 2022
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Tons
(Mt)
Au
(g/t)
Contents
(Moz)
Proven
29.36
0.295
0.28
200.21
0.33
2.09
Probable
253.59
0.311
2.53
192.79
0.24
1.49
Total Mineral Reserves
282.95
0.309
2.81
393.00
0.28
3.58
Source: The RVN Group, 2022
Notes:
1.
Tons and grades were rounded, and this may result
in minor adding discrepancies.
2.
The Mineral Reserve has been reported in accordance
with the classification criteria defined in the Regulation
S-K 1300.
3.
The Mineral Reserve is estimated using the USD1,823/oz, ZAR15.60/USD
and ZAR914,294ZAR/kg financial parameters.
4.
No mining losses or dilution has been applied
in the conversion process nor has a mine call factor
been applied.
5.
Tonnage and grade RoM delivered to the processing
plant.
6.
The attributable Mineral Reserve is 100% of the total Mineral
Reserve.
The QP responsible
for the
reporting and
sign-off of
the Mineral
Reserve is
Professor Steven
Rupprecht.
Professor Rupprecht
is a Fellow
of the Southern
African Institute of
Mining and Metallurgy
(SAIMM) with
more than five years of experience relevant to the evaluation and
reporting of TSF Mineral Reserves.
Table 12.5
depicts the
Mineral Reserve
reconciliation between
30 June
2021, and
30 June 2022.
Some
20.48Mt was
depleted through
mining operations;
66.04Mt was
removed from
the Mineral
Reserve by
the removal of the Grootvlei TSFs from the LoM plan;
2.94Mt was subtracted due to survey adjustments,
and a
further 192.79Mt
added to
the LoM
plan with
the inclusion
of the
Daggafontein TSF
and 6.72Mt
for
additional
TSFs
upgraded
from
Indicated
Mineral
Resources
to
the
Probable
Mineral
Reserve
category.
Based
on the
above,
a total
tonnage
of 110.06Mt
has
been
added,
resulting
in
a 30
June
2022 Mineral Reserve of 393.00Mt at a grade of 0.28g/t.
Table 12.5:
Mineral Reserve Reconciliation
Source
Tons
(Mt)
Au Grade
(g/t)
Content
(Moz)
Mineral Reserve as at 30 June 2021
282.95
0.31
2.81
Depletion through Mining Operations
(20.48)
0.33
(0.22)
Survey Adjustment
(2.94)
0,20
(0.01)
Inclusion of Daggafontein TSF in the LoM Plan
192.79
0.24
1.49
Exclusion of a Grootvlei TSF
(66.04)
0.26
(0.55)
Inclusion of 4 TSFs in the LoM Plan
6.72
0.26
0.06
Mineral Reserve as at 30 June 2022
393.00
0.28
3.58
Source: The RVN Group, 2022
Note: Quantities and grades have been rounded to two
decimal places,
therefore minor computational errors may occur.
The
various
modifying
factors,
i.e.,
mining,
metallurgical,
processing,
infrastructure,
economic,
marketing, legal,
environmental,
and governmental
factors, will
be discussed
in the
following Items
of
this Report.
Technical Report Summary of the material Tailings Storage
Facilities
151
12.6
QP Statement on the Mineral Reserve Estimation
The Mineral Reserves declared are estimated from the
30 June 2022 LoM plan which was
developed for
the Ergo operations and is based on the Mineral Resource Estimates as at
30 June 2021, depleted to 30
June 2022 together with a
set of modifying factors based
on recent operational results,
and economic
inputs provided by
Ergo.
The assumptions applied
in determining the
modifying factors and
economic
inputs are reasonable and appropriate. The LoM plan is in sufficient detail to ensure achievability and is
based
on
historical
achievements.
All
the
inputs
used
in
the
estimation
of
the
Mineral
Reserves
have
been thoroughly reviewed and can be considered
technically robust.
Apart from the Marievale Complex (a low to medium risk
due to ownership issues), the QP applies a low
risk
to the
Mineral
Reserves
but acknowledges
there
are
several
external
factors that
can
impact
on
Mineral Reserves, such as
infrastructural, marketing, financial,
environmental,
social and governmental
aspects.
Technical Report Summary of the material Tailings Storage
Facilities
152
13
Mining Methods
Ergo’s
business
is
the
retreatment
of
old
gold
bearing
sand
dumps
and
slimes
dams
(termed
TSFs)
to
recover gold. Consequently, Ergo has acquired an extensive inventory of gold bearing sand and slimes
TSFs spread across the Central
and East Rand goldfields produced from
the historical processing of gold
ores of
the Witwatersrand
Supergroup,
by the
gold
mines that
operated
across the
gold
fields. These
mines are now mostly
defunct and stretch from
the Crown, City
Deep and Knights processing
plants in
the Central Rand to the south of Johannesburg to the Grootvlei Mine in the East Rand over some 70km.
The result of
Ergo’s retreatment
is the creation
of a ‘new’
TSF, which
tailings are deposited
on a mega
TSF (Brakpan/Withok TSF)
designed to modern
standards. In
this way, Ergo
plays a dual
role in creating
value and cleaning up the environment.
Ergo consists of
the processing plant
and pipeline infrastructure,
the mining rights,
licenses and permits
to access
a large
number of
surface Mineral
Resources (old
tailings, slimes
and sand
dumps) and
the
active Brakpan/Withok TSF.
Table 13.1 indicates Ergo’s historical operation
results. The results show that
since 2017 Ergo has declined
from
nearly
25Mtpa
to
21.5Mtpa.
During
the
2020
and
2021
financial
years
(FYs),
production
was
adversely affected by
the Covid-19
pandemic and
in 2022 was
influenced by
power restrictions (load
shedding).
The 2022
tonnage profile
was also
lower due
to a
deliberate decision
by management
to
mine higher grade material as part of a clean-up operation which
in turn sacrificed low grade volume.
Although operational tonnage was lower than planned, operational performances
were boosted by a
higher
gold
price
received
for
FY2022
(ZAR894,409/kg),
FY2021
(ZAR917,996/kg)
and
FY2020
(ZAR768,675/kg) reporting robust
net cashflows. Ergo
has adjusted
the planned RoM
tonnage in the
2022
LoM plan targeting about 22Mtpa in the short to medium term
and 21.6Mtpa in the longer term.
Table 13.1:
Historical Ergo Operational Results
Year
FY2022
FY2021
FY2020
FY2019
FY2018
FY2017
Tonnage (t) ('000)
21,111
22,952
20,228
23,162
24,281
24,958
Gold Produced (kg)
4,156
4,263
3,989
4,493
4,679
4,265
Yield (g/t)
0,188
0,186
0,197
0,194
0,193
0,171
Source: DRDGOLD, 2022
13.1
Mining Method
The current mining methods
applied by Ergo are
suitable for all TSFs (dumps)
(Figure 13.1). No selective
mining will occur with the entire TSF being
processed. No selective mining is the result
of four conditions
inherent in the DRDGOLD operation of reclaiming the dumps:
●
there is nowhere on the mining sites to dump the below cut-off
grade material;
●
the mining method is not conducive to selective
mining;
and
●
the operation is a
rehabilitation exercise, and all mineralized
material must be removed
from the
site, and
it is,
therefore, economically beneficial
to process
all material, even
low-grade material.
●
Concurrent rehabilitation
takes place
which reduces
the environmental
impact as
well as
the
rehabilitation liabilities
Technical Report Summary of the material Tailings Storage
Facilities
153
Figure 13.1:
Typical Tailing Storage Facility
Source: DRDGOLD, 2022
13.1.1
Hydraulic Mining
The
use
of
water
plus
energy
to
mine
unconsolidated
material
has
a
long
history.
Documented
and
physical evidence indicates
widespread and sophisticated
use in the Californian
goldfields in the mid-
19th century. Thousands
of kilometers
of ditches and
flumes were constructed
to gravitate
water from
the mountains
to generate
sufficient
pressure
to “flush”
the
alluvial
gravel
beds into
sluices. In
recent
years,
however,
the
most
popular
techniques
have
been
based
on
hydraulic
mining
used
to
mine
unconsolidated
materials,
alluvial
deposits,
freshly
blasted
ores
and
for
the
recovery
(or
mining)
of
dewatered TSFs.
Hydraulic mining is
loosely defined as excavating
material from its
in situ state
using water. A stream
of
water is directed at the mining face to
mechanically breaking and/or softening the material so that the
water flow
can carry
it away.
The application
or
effectiveness
of the
method is
a function
of various
factors
ranging
from
the
size,
velocity
and
pressure
of
the
water
stream
to
the
location,
hardness,
particle size and moisture content of the material to be mined.
Hydraulic
mining
is
typically
undertaken
using
100mm
or
150mm
monitor
guns
(Figure
13.2),
with
increased production achieved by
including additional units. Hydraulic
mining provides a high degree
of
flexibility
that
allows
simultaneous
mining
at
several
points
over
a
wide
range
of
production
rates.
Consequently, grade blending is readily achievable.
Technical Report Summary of the material Tailings Storage
Facilities
154
Figure 13.2:
Example of Hydraulic Mining
Source: DRDGOLD, 2022
Hydraulic
mining
in
semi
or
near-saturated
conditions
is
possible
and
common
and
has
a
clear
advantage over load-and-haul operations.
Hydraulic mining does
not create,
but rather ameliorate the
airborne
dust
problem
often
associated
with
fine
TSFs
and
dry
mining
techniques.
A
typical
generic
hydraulic mining system is shown in Figure 13.3.
Technical Report Summary of the material Tailings Storage
Facilities
155
Figure 13.3:
Hydraulic Mining Process Diagram
Source: J Engels,
No Date
Note: the pumps have been excluded for clarity
The planning of hydraulic mining considers several
factors:
●
the required production rate;
●
the life of the operation;
●
the type of material to be
mined (including hardness, density,
grading, specific gravity,
degree
of contamination (vegetation));
●
the site topography, shape and form of the TSF;
●
the slurry quality requirements;
●
the pumping distances;
and
●
water, power, equipment and labor availability.
Considering
the
abovementioned
aspects
allows
the
size
and
number
of
monitor
guns
to
be
determined. Essentially, most applications
require 1m
3
of water per dry ton
to be mined aiming for
50%
solids.
A
monitor
gun
can
be
fitted
with
different
diameter
nozzles
(100mm
or
150mm)
that
allow
production rates to be “fine-tuned”.
Technical Report Summary of the material Tailings Storage
Facilities
156
Before the
slurry enters
the pumping
facilities, it
is usually
necessary to
pass the
slurry through
a screen
or
series
of
screens
depending
upon
the
degree
of
contamination
and
oversize.
Satellite
pumps
transport
slime
into
a
thickener
or
header
tank
ahead
of
the
processing
plant
that
accommodates
surges in flow, grading or density.
Hydraulic
mining
provides
slurry
feedstock
to
the
mineral
processing
plant
continuously.
To
maintain
production,
high
pressure
water
must
be
ensured.
Slurry
densities
and
production
rates
will
not
be
achieved
if
the
water
pressure
is
not
maintained.
Critical
to
hydraulic
mining
is
consistent
high
slurry
densities. If densities
drop, less tonnage
is delivered to
the processing plant,
thus increasing the
mining
cost. Figure 13.4 demonstrates a cross-sectional view of mining
a TSF.
Figure 13.4:
Typical Mining Method for a TSF
Source: DRDGOLD, 2018
13.1.2
Conventional Load, Haul and Slurry
A second mining method employed
by Ergo is the
use of front-end loaders
(FEL) to load slimes
and sand
(Figure 13.5). In
these cases, the
FELs load from
the bottom of
the dump and
transport the mineralized
material to a feed hopper which feeds a conveyor.
The conveyor transports (Figure 13.6 to Figure
13.8)
the mineralized
material to the
satellite pump
station where
it is
mixed with
water to form
a slurry
then
pumped to
the processing
plant. In
other cases,
the FELs
load directly
onto trucks
for transport
to the
processing plant.
Technical Report Summary of the material Tailings Storage
Facilities
157
Figure 13.5:
Example of Loading with a FEL
Source: DRDGOLD, 2022
Figure 13.6:
Example of Loading with a FEL into a Hopper
Source: DRDGOLD, 2022
Technical Report Summary of the material Tailings Storage
Facilities
158
Figure 13.7:
Example of Material on Conveyor
Source: DRDGOLD, 2022
Figure 13.8:
Slurry Point for Loading
Source: DRDGOLD, 2022
Technical Report Summary of the material Tailings Storage
Facilities
159
13.2
Mining Sections
Ergo re-treats slimes and
sand dumps from three
sections,
as depicted in Figure
13.9, the West
Section,
Central
Section, and
the
East
Section.
Figure
13.10
provides
an
overview
of the
Ergo
operations
and
pipelines from the West Rand to East Rand.
In terms of the LoM plan and the Mineral Reserve statement, the following
TSFs are considered material
for Ergo:
●
4L3 (13.1Mt);
●
Rooikraal TSF (56.8Mt);
●
7L15 TSF (17.1Mt);
●
Marievale Complex (54.1Mt);
and
●
Daggafontein TSF (192.8Mt).
The following TSFs, excluding
the material TSFs listed
above, are reported on
an aggregate basis, as
they
are included in the LoM plan and cumulatively make
the Ergo operation economically viable.
Technical Report Summary of the material Tailings Storage
Facilities
160
Figure 13.9:
Ergo Sections
Source: DRDGOLD, 2022
Technical Report Summary of the material Tailings Storage
Facilities
161
Figure 13.10:
Ergo Operations Overview
Source: DRDGOLD, 2022
Note: overview purposes only
Technical Report Summary of the material Tailings Storage
Facilities
162
13.2.1
West Rand
No Mineral Reserve was declared.
13.2.2
Central Rand Section – City Section
Mining areas located from
Soweto to City Deep
are planned to be
loaded and hauled to
the City
Deep Basin or alternatively 4L25. Slurry is
pumped from the City Deep Basin via a
600ktpm (500mm
NB pipe)
pipeline to
the Ergo
processing plant.
Operations from
the City
Section are
planned to
be completed in September 2027 and the Knights
Section will be completed in June 2024.
Table 13.2 and Table 13.4
depict the working places
in the Central Rand that
are included in the
LoM
plan
and
include
sites
that
are
being
mined
on
a
contract
basis
and
not
included
in
the
Mineral Reserve.
Table 13.2:
Central Rand (City Section)
Workplace
Tonnage
(kt)
Grade
AU
(g/t)
Recovery
(%)
Steady State
Mining Rate
(ktpm)
Commentary
3L1 Sand and 3A1
201
0.63
64.1
20
Mined in 2026
3L40
204
0.30
46.0
50
Mined in 2022 to 2023
4L42
300
0.30
46.0
75
Mined in 2022
3L43
150
0,45
52.7
50
Mined in 2022
4L2
252
0.30
46.0
100
Mined in 2022 to 2023
4L25 LG
1 518
0.31
46.1
150
Mined in 2022 to 2023
4L3
13,134
0.32
45.9
320
Mined in 2022 to 2026
4L4
4,738
0.31
47.8
140
Mined in 2023 to 2027
4L6
2,410
0.60
44.2
140
Mined in 2023 to 2024
3L30 Rob Deep Slime
216
0.60
73.3
40
Mined in 2022
3L30 Rob Deep Sand
15
1.00
62,5
20
Mined in 2022 to 2023
(Rehabilitation)
Valley Silts
3,760
0.60
64.9
80
Mined in 2022 to 2026
Genesis (3A11)
164
0.42
62.5
50
Contract-Mined in 2022
Cons Dump Cluster
794
0.63
51.4
65
Contract-Mined in 2026
Total
27,856
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
163
Table 13.3:
Central Rand (Knights
Section)
Workplace
Tonnage
(kt)
Grade
Au
(g/t)
Recovery
(%)
Steady State
Mining Rate
(ktpm)
Commentary
4A18 - E
and S Sand
130
0.60
62.2
10
Mined in 2022
4A18 - 4A30 Sand
204
0.50
55.2
17
Mined in 2022
4A18 -4A19 Sand
216
0.60
62.2
18
Mined in 2022
4A18 - 4L13 Sand
46
0.60
62.3
10
Mined in 2022
4A18 - BGM Dumps
Sand
2,256
0.60
62.8
34
Contract - Mined in 2022
4A18 - Benoni Cluster
Sand
1,200
0.56
59.6
60
Mined in 2023 to 2024
Consolidated Dumps
via 5/L/27
645
0.38
41.0
80
Mined in 2024
4L18 -Ezekiel
130
0.40
43.5
20
Mined in 2022
4L18 - 4L19 Slime
292
0.65
65.2
40
Mined in 2022
4L18 - 4L8 Slime
120
0.48
52.9
15
Mined in 2022
4L18 - Primrose Slime
398
0.60
62.3
40
Mined in 2023 to 2024
Cedar and 50/50
350
0.36
37.7
40
Mined in 2023 to 2024
Cason Slime and
Lycast Clean-up
50
0.63
64.2
15
Mined in 2022
Cedar and 50/50
881
0.47
52.3
100
Mined in 2022
Total
6,919
Source: The RVN Group, 2022
13.2.3
East Rand Section
Table
13.4
indicates
the
TSF
planned
working
sites
located
in
the
East
Rand
-
Ergo
Section,
including sites that are being mined on a contract basis,
and not included in the Mineral Reserve.
Technical Report Summary of the material Tailings Storage
Facilities
164
Table 13.4:
East Rand Section (Ergo Section)
Workplace
Tonnage
(kt)
Grade
(g/t)
Recovery
(%)
Steady State
Mining Rate
(ktpm)
Commentary
4L14
6,638
0.28
48.1
270
Mined 2023 to 2025
4L30
3,512
0.33
48.0
270
Mined 2022 to 2024
4L39
9,008
0.42
54.3
360
Contract - Mined 2023 to
2025
4L40
2,281
0.27
44.4
300
Contract -Mined 2025 to
2026
Cons Dump Benoni
1,912
0.48
63.5
50
Contract - Mined 2024 to
2027
4L50 Elsburg
3,418
0.26
39.5
280
Plan Finish in 2023
4L49 Elsburg
290
0.26
41.3
290
Mined 2023
4L47 Elsburg
3,219
0,26
41.3
270
Site clean up
Benoni Slime
500
0.34
43.8
130
Mined 2023
5A10
975
0,61
65.0
70
Completed in 2022
5L27
3,829
0.40
64.9
140
Mining 2022 to 2026
5L27 Sand
4,288
0.28
60.0
140
Mining 2026 to 2028
5L27 Scoops Slime
1,155
0.60
67.9
100
Contract - Mined 2022 to
2023
5L27 Pipeline
1,002
0.60
62.8
90
Mined to 2024 to 2025
5L29 van Dyk
2,355
0.26
42.3
220
Mined to 2023
6L13
2,874
0.60
58.3
240
Mined 2028 to 2029
6L14
6,980
0.32
50.0
291
Mined 2027 to 2029
7L15
17,646
0.26
42.9
600
Mined 2027 to 2033
Rooikraal
56,763
0.26
34.2
380
Mined 2023 to 2034
Marievale 7L4
17,590
0.34
46.0
750
Mined 2025 to 2027
Marievale 7L5
6,980
0.29
47.4
750
Mined 2027 to 2029
Marievale 7L6
12,760
0.26
41.3
350
Mined 2029 to 2031
Marievale 7L7
16,784
0.32
40.9
550
Mined 2028 to 2031
Daggafontein
192,800
0.24
35.0
1,800
Mined 2031 to 2041
Total
375,559
Source: The RVN Group, 2022
13.3
Mine Design and Schedule
The technical work/studies conducted by Ergo to support the conversion of Mineral Resources
to
Mineral
Reserves
and
to
generate
the
on-going
LoM
plan
are
at
least
to
a
PFS
level
of
accuracy (i.e., +/-25%). The LoM schedule mines
approximately 21Mtpa from several TSF sites.
Table 13.5 provides
the modifying
factors used
to convert
the Mineral
Resources to
a Mineral
Reserve used in
the 19-year LoM
plan.
Due to the
nature of mining
tailings and slimes
TSFs, no
mining
loss
or
dilution
is
applied
in
the
conversion
process.
Recovery
factors
are
based
on
actual plant performances, which are reconciled
annually.
Technical Report Summary of the material Tailings Storage
Facilities
165
Table 13.5:
Summary of Modifying Factors for LoM Plan
Source Area/Plant
MCF
(%)
LoM Recovery
(%)
Mining Loss
(%)
Dilution
(%)
Total Ergo Operation
100
40.9
0
0
Source: The RVN Group, 2022
Note: Tailing recoveries vary on a TSF-by-TSF basis
Table 13.6 provides the
30 June 2022 19-year LoM
tonnage and recovered gold schedule
used
to support the declaration of the Mineral Reserve. The LoM plan has a cut-off grade of 0.24g/t
Au, which is below the planned LoM head grade of 0.28g/t Au. The working cost of ZAR90.86/t
is based on the
LoM plan.
The current LoM plan
is very robust. However,
it remains sensitive
to
RoM grade, gold price, exchange rate, recovery and
operating costs.
Technical Report Summary of the material Tailings Storage
Facilities
166
Table 13.6:
Ergo Forecast Production from July 2021 to June
2034
Years
1
2
3
4
5
6
7
2022 to 2023
2023 to 2024
2024 to 2025
2025 to 2026
2026 to 2027
2027 to 2028
2028 to 2029
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Sand
3,409
1,380
4,684
1,767
2,560
1,116
2,450
885
2,615
839
1,549
605
720
466
Slime
19,501
2,760
18,290
2,873
19,020
2,873
18,038
2,437
19,340
2,628
19,479
2,486
20,200
2,479
Total
22,910
4,141
22,974
4,561
21,580
3,988
20,488
3,322
21,955
3,467
21,028
3,091
20,920
2,945
Years
8
9
10
11
12
13
14
2029 to 2030
2030 to 2031
2031 to 2032
2032 to 2033
2033 to 2034
2034 to 2035
2035 to 2036
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Sand
720
466
720
466
720
466
515
333
0
-
0
-
0
-
Slime
21,145
2,727
21,599
2,555
21,585
1,979
21,600
1,852
21,703
1,854
21,600
1,814
21,600
1,814
Total
21,865
3,193
22,319
3,021
22,305
2,445
22,115
2,185
21,703
1,854
21,600
1,814
21,600
1,814
Years
15
16
17
18
19
Total
2036 to 2037
2037 to 2038
2038 to 2039
2039 to 2040
2040 to 2041
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Tons
(kt)
Recovered
Au
(kg)
Sand
0
-
0
-
0
-
0
-
0
-
20,662
8,788
Slime
21,600
1,814
21,600
1,814
21,600
1,814
21,600
1,814
18,572
1,560
389,672
41,870
Total
21,600
1,814
21,600
1,814
21,600
1,814
21,600
1,814
18,572
1,560
410,334
50,658
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
167
13.4
Geotechnical and Geohydrology
The
Witwatersrand
TSFs
have
been
successfully
and
economically
exploited
for
some
time,
and
the
geotechnical and geohydrology characteristics are well understood from practical experience.
A safe
bench
height
is
dependent
upon
the
material
being
mined
and
is
also
influenced
by
the
phreatic
surface within the
dump. No
geotechnical or hydrological risks
surrounding Ergo’s operations
have been
identified that would
impact the declaration of
a Mineral Reserve. As
no open pit
mining is taking
place,
the mine design
does not account
for slope angles
but rather the
natural angle of
repose from hydraulic
mining. To ensure the competency of the wall, an
angle of 45
˚
is used for mining.
No geotechnical or hydrological aspects affecting the surface deposits are significant to the operation
and the QP is unaware of any incidents regarding
unexpected highwall failure.
Mining bench heights are in the order of 15m.
Hydraulic mining provides slurry feedstock to
the processing plant continuously. To maintain
production,
high pressure
water must
be ensured.
Slurry densities
and production
rates will
not be
achieved if
the
water pressure is not maintained. Critical to hydraulic mining is
consistent high slurry densities. If densities
drop, less tonnage is delivered to the processing
plant,
thus increasing the unit mining cost.
The following series of steps offer an overview of the
hydraulic mining process:
●
the water monitor
washes the slime
material between
10m to 15m
high benches
with a mining
width of 15m and a length of 9m or more (“mining
cut”);
●
monitoring will be conducted from the bench of the
TSF (i.e., top-down approach);
●
the
resulting
slurry
stream
is
channeled
in
the
15m
wide
mining
cut,
which
forms
a
trough
to
ensure a good flow of the slurry material to the pumps,
which will then transport the slurry to the
processing plant;
and
●
approximately
6,950t/d
(316tph)
per
water
monitor
is
achievable
equating
to
four
hydraulic
monitors to produce 600ktpm.
The operating position of the monitor will be on the top of the mining cut and operating at a 45
˚
angle,
as seen in Figure 13.11.
The reclamation gun position
and bench angles are
based on experience and
on-site observations.
Technical Report Summary of the material Tailings Storage
Facilities
168
Figure 13.11:
Hydraulic Mining with Monitor showing Distance and Angle
Source: DRDGOLD; and The RVN Group, 2022
When
FELs
are
used,
care
is
taken
to
ensure
that
there
is
no
undermining
of
the
dump
highwall
with
operators being
cognizant
of the
risks related
to
slumping highwalls.
Dozers are
used to
remove
over
hanging
material
where
required.
No
geotechnical
or
hydrological
aspects
affecting
the
surface
deposits are significant to the operation and the QP is unaware of
any incidents regarding unexpected
highwall failure.
13.5
Requirements for Stripping
As
no
underground
mining
is
done,
there
is
no
underground
development
and
backfilling
required.
Other than minimal precleaning with a dozer of the
top of the TSFs no pre-stripping is required at Ergo.
Technical Report Summary of the material Tailings Storage
Facilities
169
13.6
Mining Equipment and Personnel Requirements
The equipment required for hydraulic mining are as follows:
●
track mounted hydraulic monitors;
●
water columns, 250mm diameter pipes to feed water to
the hydraulic monitor;
●
grizzly screen to remove debris from slurry;
●
satellite pump stations (spindle pumps) to pump slurry
to main pump station;
and
●
main transfer pump station.
For
loading
of
sand,
excavators,
dozers,
FELs,
trucks
and
conveyors
are
required
as
shown
in
Item 13.2.2.
Ergo
employs
776
full
time
employees
and
1,628
special
service
providers,
with
service
providers
deployed mostly in security, reclamation,
and tailings deposition.
13.7
Mine Plans
13.7.1
Introduction
The QPs have identified the material TSFs in the Mineral
Resource and Mineral Reserve.
In terms of the
LoM plan and
the Mineral Reserve
statement, the following
TSF are considered material
for Ergo:
●
4L3 (13.1Mt);
●
Rooikraal TSF (56.8Mt);
●
7L15 TSF (17.1Mt);
●
Daggafontein (192.8Mt);
and
●
Marievale Complex (54.1Mt).
13.7.2
Central Rand
The 4L3 TSF accounts for 13.1Mt and is considered material to Ergo. The 4L3 TSF has commenced
mining
operations in 2022 achieving a steady state mining rate
of 3.2Mtpa and is completed in 2026.
13.7.3
East Rand (Ergo)
The Rooikraal
TSF is scheduled
to commence
mining in
2023 and completes
mining operations
in 2034
Rooikraal starts up at
4.5Mt in 2023, with steady
state production of 5.4Mt
between 2027 and 2033.
The
final year produces 4.4Mt as the remnant of the TSF is removed.
Mining of the Marievale Complex is scheduled to commence in 2025,
starting with the mining of the 7L4
TSF, in 2027 the 7L5
TSF embarks with 7L6 and 7L7
TSFs begin mining in 2028. The
Marievale complex starts
production
at 4.7
Mtpa
and
reaching
a steady
state mining
rate of
9.0Mtpa
in
2028 with
production
Technical Report Summary of the material Tailings Storage
Facilities
170
influenced
by
the
various
TSFs
starting-up
or
winding
down
production.
The
mining
of
Marievale
is
conditional
upon
the
successful
resolution
of
the
conflicting
ownership
claim
by
the
owner
of
the
freehold on which a part of the complex is situated.
Mining of the Daggafontein TSF commences in October 2031. The top cut is mined from 2031 until 2033,
the middle
cut of
the TSF
being mined
for four
years, from
2034 until
2037, and
the bottom
cut mined
from
2038
to
2041
(Figure
13.12,
Figure
13.13
and
Figure
13.14).
Over
the
11-year
period
the
Daggafontein TSF produces 192.8Mt at a grade of 0.24g/t
Au.
Figure 13.12:
Daggafontein TSF Top Cut Mining Sequence
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
171
Figure 13.13:
Daggafontein TSF Middle Cut Mining Sequence
Source: The RVN Group, 2022
Figure 13.14:
Daggafontein TSF Bottom Cut Mining Sequence
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings Storage
Facilities
172
14
Processing and Recovery Methods
14.1
Introduction
The
Ergo
processing
plant
located
in
Brakpan,
is
Ergo’s
flagship
metallurgical
plant
which
currently
targets
throughput
between
1.8Mtpm
to
2.0Mtpm.
The
City
Deep
processing
plant
has
been
reconfigured to operate
as a milling and
pump station and feed
the Ergo processing plant
via a 50km
pipeline. The
City Deep processing
plant processes
mineralized material
from TSFs of
the Central
Rand
areas (i.e., Johannesburg, Germiston,
and Boksburg), with mining
operations scheduled to close
in 2027.
Knights Plant treats sand and slime and will operate until
2024.
The Ergo
processing plant
follows the
conventional
method of
extracting
gold. The
plant has
been in
operation for more than 30 years, with minor improvements
conducted on a regular basis.
Ergo
retreats
historical
tailings
and
the
remaining
gold
in
the
TSFs
is
finely
disseminated
within
the
material. The gold
does not respond
to physical recovery
methods. Direct
cyanidation has
been used
for decades to solubilize the gold and then
recover it by hydrometallurgical techniques.
The Carbon in
leach (CIL)
process is
used with
elution and
final recovery
by zinc
precipitation which
produces >85%
bullion quality.
14.2
Plant Feed Grade and Metallurgical Test Work
The Ergo processing plant is fed from at least eight different
mining sites (including sand and slime) that
are being mined
and fed
into the plant
at any
one time. Daily
composites are
submitted to
the assay
laboratory for
grade determination
to assist
with the
management of
the operations.
A sub-sample
is
split
and
composite
samples
over
a
week
for
metallurgical
test
work.
A
bottle
roll
test
is
conducted
utilizing the same parameters
that are used
on the full-scale
plant. Should any
deviations be reported,
further investigations are undertaken.
Prior
to
commencing
reclamation
of
any
mineralized
material,
a
comprehensive
drilling
exercise
is
carried out.
As part
of the
evaluation, sub-samples
are sent
to Ergo’s
in-house
metallurgical
research
laboratory for testing to assess the amenability of the material to cyanidation
and what recoveries can
be expected. Mineralogy work is
not carried out on
a routine basis but
on a needs-basis associated with
the exploration program.
Sand material that
is coarse in
nature, is first
milled prior to
cyanidation, while slimes
material is processed
without pre-milling.
All feed
streams are
combined before
removing extraneous
oversize, which
could
contaminate
the
activated
carbon,
over
linear
screens.
The
material
is
leached
with
cyanide
at
an
elevated
pH
in
mechanically
agitated
tanks.
Carbon
is
then
used
to
adsorb
the
dissolved
gold.
The
loaded carbon is
removed from the
circuit and the
gold eluted off
the carbon.
The gold is
then finally
recovered using zinc precipitation and smelting of bullion
bars.
The tailings are pumped to a
large Mega TSF (Brakpan/Withok TSF) located south of
the Ergo processing
plant.
The
Brakpan/Withok
TSF
as
of
June
2022
has
a
remaining
capacity
of
approximately
(~950Mt)
after
implementation
of
the
facility’s
final
life
design.
The
Ergo
plant
capacity
is
64,000tpd
and
gold
recovery is between 35% and 50%.
A 100% mine call factor is applied at the Ergo processing
plant.
Technical Report Summary of the material Tailings Storage
Facilities
173
For planning purposes, Ergo uses the RoM head grade (i.e., the grade of the RoM material
as delivered
to the processing plant)
and the anticipated residue grade to estimate the recovery which is
the head
grade minus residue grade multiplied by the tonnage treated.
During
the
life
of
each
TSF,
the
mined
grade
is
monitored
and
compared
to
the
estimated
Mineral
Reserve grade. Generally, these grades tend to track each
other. When the TSF is completely mined, a
final reconciliation is conducted.
Metallurgical test work is carried
out routinely using laboratory equipment
and leach conditions, which
closely mimic the full-scale operation.
The test work is considered representative
as historical results are
consistent, and generally
minor deviations are
seen on numerous
tests from the
same source material.
The material differs slightly
in terms of head grade,
particle size and origin, so
different recovery factors
are used for each
source. Due to the consistency of
the exploration and metallurgical test work,
no bulk
sampling or pilot scaling test work is conducted.
No specific
assumptions or allowances
are made
for deleterious
elements in the
material. They are
either
screened out before entering the processing plant or if they cannot be removed,
the metallurgical test
work results will include the impact. If the impact is too great, the
material will not be treated.
Cyanidation of gold bearing material, with elution of gold from the loaded carbon is a tried and tested
process and there is nothing novel about the process.
Technical Report Summary of the material Tailings Storage
Facilities
174
Figure 14.1: Process Flow Diagram
Technical Report Summary of the material Tailings Storage
Facilities
175
Technical Report Summary of the material Tailings Storage
Facilities
176
Technical Report Summary of the material Tailings Storage
Facilities
177
Table 14.1 indicates
the process recoveries
for the various
plants for the
past two years,
and the planned
average recoveries
over the
19-year LoM.
The recoveries
are based
on metallurgical
test work
for the
various tailings dumps, slimes and silted
vleis that are scheduled to
be mined over the 19-year
LoM plan.
Table 14.1:
Ergo Process Recoveries
Description
2020 to 2021
2021 LoM Average
2022 LoM Average
Total Mine
45.9%
48.9%
40.8%
Source: DRDGOLD, 2022
Note: The drop in the 2022 recovery is due to the inclusion
of the Daggafontein TSF which has a recovery of
35%.
14.3
Mineral Process and Equipment Characteristics
The metallurgical
process and
equipment used
at the
Ergo processing
plant is
well tested
and utilised
by numerous tailings retreatment operators in South Africa.
14.3.1
Reception
Material received
from the
various mining
sites is
first sampled
through two
in one
slurry samplers
and
then thickened in four large thickeners to produce an underflow with an SG of 1.45 for leaching and for
recovery of excess water.
14.3.2
De-sanding Section
Thickened
material
from
the
four
large
thickeners
is
pumped
to
a
distribution
box
in
the
de-sanding
section. Here the tailings can be directed to
four linear screens which have an 850µm aperture cloth for
the removal of
debris to prevent
contamination of
the carbon. The
undersize from the
linear screens is
pumped up to a two-way distribution box ahead of the leach.
14.3.3
Carbon-in-Leach
The CIL section
comprises of two
streams of 11
tanks per stream.
Each tank
has a capacity
of 2,000m
3
and at
a throughput
of 1.8Mtpm
gives
a leach
residence time
of about
11.5 hours,
with the
first tank
being used for pre-conditioning with lime and oxygen.
Cyanide is added
to the second and
fourth tank in
the leach train.
Carbon is present
in all but
the first
two tanks
and is
retained by
interstage screens.
Carbon is
moved counter-current
up the
leach using
recessed
impeller
pumps.
The
carbon
concentration
in
the
tanks
is
about
10g/l.
Loaded
carbon
is
transferred
to
the
four
loaded
carbon
hoppers
over
vibrating
screens.
Loaded
carbon
values
vary
between 200g/t and 300g/t.
CIL
tailings
flow
through
residue
samplers
before
passing
over
four
safety
linear
screens.
Screened
material
reports to
a residue
sump from
where it
is pumped
to the
Brakpan/Withok
TSF
through three
tailings pipelines using five of six installed D-frame
pumps.
14.3.4
Carbon Treatment
Loaded carbon
is acid
treated in
8.5t batches
in three
independent acid
wash columns.
The carbon
then reports to
three of the
four elution columns.
The fourth column
is used to
scavenge gold from
the
zinc precipitation tails.
Technical Report Summary of the material Tailings Storage
Facilities
178
Loaded carbon is first washed with dilute hydrochloric acid to remove acid soluble contaminants. Acid
washed carbon
is transferred
to the
elution column
which is
operated at
elevated temperatures
and
pressure to strip gold off the carbon using a cyanide/caustic
solution (eluant).
The
eluate,
which
now
contains
the
gold
in
solution,
is
contacted
with
ultra-fine
zinc
powder
to
precipitate the
gold. This
gold bearing
sludge is
then filtered
in a
plate and
frame filter.
Sludge is
then
calcined at 600
˚
C before being smelted in an arc furnace and cast into
dorè bars.
Eluted
carbon
is
regenerated
in
two
rotating
kilns
at
about
750
˚
C.
In
total,
about
100
elutions
are
conducted monthly.
14.3.5
Plant Services
Instrument Air:
Instrument air
is supplied
to the float
from one compressor
house and
the remainder
of
the processing plant from a centrally located facility.
Process Water:
Process water is made up of thickener overflow and return dam water and
is distributed
throughout the processing plant by a network of pumps and
pipes.
Fresh Water:
The Rand Water
Board water is
received at a
reservoir for use
in the processing
plant and
directly for elution water, fire hydrants and human
consumption.
Power:
Bulk power is supplied to the Ergo processing plant
by the Ekurhuleni Metropolitan Municipality.
Natural Gas:
Natural gas is obtained by a pipeline from Sasol and
used for elution heating purposes.
Assay Laboratory:
All assays are done by the MAED laboratory which is
located on the Ergo processing
plant site but is operated by an independent third party.
14.4
Personnel Requirements
Ergo
employs
776
full
time
employees
and
1,628
special
service
providers,
with
service
providers
deployed mostly in security, reclamation (mining) and tailings deposition. The processing plants employ
376 persons.
14.5
Energy and Water Requirements
Energy and water requirements are discussed in Item
15.3 and 15.5.
14.6
Process Materials Requirements
Ergo has access to all required
process material required through their local or international
suppliers.
Technical Report Summary of the material Tailings Storage
Facilities
179
15
Infrastructure
Ergo
currently
mines
the
existing
gold
TSFs and
sand
dumps in
the
Johannesburg
and
Brakpan
areas
with
slurry
pumped
via
pipelines
from
the
numerous
mining
operations
to
the
Ergo
processing
plant
located in Brakpan.
The
infrastructure
required
to
support
the
LoM
plan
is
essentially
in
place,
with
future
infrastructure
requirements
being
designed
and
estimated
by
Ergo
to
a
PFS
level
of
accuracy
(i.e.,
+/-25%)
with
a
maximum
level
of
contingency
of
15%.
Infrastructure
requirements
and
capital
costs
are
based
on
current mining operations, as the
mining methodology applied
to exploit the TSFs and sand
dumps are
substantially
the
same
throughout
the
LoM
plan
with
no
significant
operational
changes
expected
between current and planned future operations.
The use of railways, port facilities, dams, leach pads and other infrastructure components not discussed
below as they are not material infrastructure components
the Ergo operations.
15.1
Roads
Access to
the mining
sites is
via current
municipal and
regional road
networks with
no construction
or
upgrading of unpaved roads.
15.2
Site Offices and Workshops
The
mining
contractors
establish
site
offices
as
part
of
the
mining
contract.
Workshops
for
the
maintenance of roads, pumps and pipelines are based at the
Ergo processing plant, and no additional
infrastructure is required.
15.3
Power
Bulk
power
is
supplied
to
Ergo
by
Eskom,
City
Power
and
the
Ekurhuleni
Municipality.
The
power
grid
infrastructure
serving
the
East
Rand
is
particularly
extensive,
with
electrical
power
being
received
through several alternative substations on the Eskom grid. Mining sites are supplied via several separate
feeders.
The Eskom power grid
has been negatively affected by poor
power availability and subsequently, it has
at times been unable
to meet power demand.
Some load shedding
has taken place
during 2021 and
2022, affecting the country and Ergo. Electrical
demand is approximately between 60MW and 70MW.
Power
supply
is
viewed
as
a
risk
to
Ergo
operations.
A
risk-mitigating
measure
that
has
been
implemented
by
Ergo
is the
provision
of back
-up
power and
other
engineering
upgrades
to
prevent
plant
choke-up/silt-down
during
power
interruptions.
These
measures
have
enabled
the
processing
plant to
resume full
production without
extensive delay
after each
power interruption.
A 7MVA
diesel
emergency power plant is also available as backup
.
Technical Report Summary of the material Tailings Storage
Facilities
180
Ergo has a curtailment agreement with Eskom
whereby the total consumption is reduced on request by
an
agreed
percentage
during
load-shedding
hours.
This
involves
reducing
the
total
consumption
by
between 4MVA and 8MVA during load-shedding hours. The reduction in the
power consumption results
in the
operations maintaining
an uninterrupted
tonnage
throughput, but
recoveries
are lower
due
to
certain parts of the process plant not operating during
the load reduction periods.
15.4
Pumps and Pipelines
Slurry transport is mainly via pipelines that carry it to the Ergo processing plant
(Figure 15.1).
Ergo uses a
standard
set
of pipes
and
pumps
(500mm
pipes).
Equipment
selection
is
based
on
the
most
suitable
sizes from the standard equipment range.
Figure 15.1:
Above Ground Pipeline System
Source: DRDGOLD, 2022
The pipelines
are
mainly
installed
above
ground,
providing
easy
maintenance
access
and
making
it
easier
to identify
and
rectify
any
failures on
these
pipelines.
Where
necessary, pipe
bridges
are
used
along the pipeline routes to cross streams and rivers.
The existing pumping and
slurry pipeline systems are
managed through a supervisory
control and data
acquisition
(SCADA)
system.
The
SCADA
system
allows
Ergo
to
operate
the
equipment
remotely.
Thereby, Ergo can monitor the entire pipeline system via a centralized system. For example, pumps and
valves
can
be
used
(open/closed
or
on/off),
and
readings
taken
(pressures
and
flows)
from
the
centralized site, with no actual human-machine interface on the actual site. As the pumps are installed
with a
duty and standby
configuration, the operation
of the
existing and planned
pumping and pipeline
systems should be adequate to support the requirements
of the LoM plan.
Technical Report Summary of the material Tailings Storage
Facilities
181
Operations west of the
Ergo processing plant
are serviced by pipeline
and other existing infrastructure.
The
Marievale
and
Daggafontein
mining
areas
east
of
the
processing
plant
have
pipeline
permits/servitudes/surface
rights
in
place.
The
QP
has
not
identified
any
impediments
that
would
prevent the construction of the necessary infrastructur
e
to support the LoM plan.
15.5
Water
The primary uses for water
are in the Ergo processing
plant and for hydraulic
mining of the various
TSFs.
Water used
for hydraulic mining
turns the
dry tailings
into a
slurry, which is
then pumped to
the processing
plant for
processing. Excess
water recovered
at the
thickeners in
the processing
plant is
then returned
to the hydraulic mining sites for re-use.
In 2017,
Ergo completed
the construction
of a
central
water reticulation
plant
to give
it the
ability
to
deliver water to all corners of the operation and return
it through a fully integrated closed system.
Currently
60%
to
70%
of
all
process
water
make
up
at
Ergo
is
drawn
from
the
Brakpan/Withok
TSF
to
various
reclamation
sites
by
way
of
return
water
columns.
A
further
6%
to
11%
of
process
water
top-up needs are
from treated underground acid
mine drainage (AMD),
drawn from a
facility operated
by the Trans-Caledon Tunnel Authority (TCTA) from whom DRDGOLD secured the right to
use up to 30Ml
of AMD water
per day. The Ekurhuleni
City Council’s wastewater treatment
facility at Rondebult supplies
less than 1%, depending on the
rate at which water flows into
the waste facility and another 15% to 20%
is from lakes
and dams in
the region that
captures the
inflow of seasonal
rain and storm
water inflows,
harvested in terms of the requisite extraction licenses. Potable water is used only where the sensitivity of
equipment requires it
and for certain
early stages of
irrigation to settle
in newly established
vegetation
on TSFs.
Given
the
location
of
the
Ergo
operations,
the
QP
does
not
foresee
the
likelihood
of
the
operations
being curtailed
due to a
water shortage. However,
the future increased
reliance on
water purchased
from Rand Water will add materially to the operating costs.
15.6
Infrastructure
General arrangement drawings
are provided for the Rooikraal TSF to demonstrate design work
typical
of a mining site (Figure 15.2). The actual construction
work will vary slightly to account for specific site
conditions,
but generally,
the infrastructure is common from site to site,
with 52 TSFs planned to be
mined over the 19-year LoM plan.
Technical Report Summary of the material Tailings
Storage Facilities
182
Figure 15.2: Rooikraal General Arrangement -
Site Layout
Technical Report Summary of the material Tailings
Storage Facilities
183
Technical Report Summary of the material Tailings
Storage Facilities
184
Source: DRDGOLD, 2022
Technical Report Summary of the material Tailings
Storage Facilities
185
15.7
Tailings Disposal
The
Brakpan/Withok
TSF
(Figure
15.3)
is
a
single
large
tailings
dam
that
covers
700ha
at
its
base
and
500ha at its current elevation and has a
perimeter of around 12km. The Brakpan/Withok TSF was built by
cycloning
the tailings
at the
point of
deposition
out with
the larger
particles from
the tailings,
forming
the dam wall. The annual rate
of rise is between 3m
and 4m. The fines from the
cyclones run out into the
center of the dam. This generates
a more stable wall with
the finer material safely stored inside
the TSF.
With
the
deposition
rate
from
1.8Mtpm
to
2.0Mtpm
the
use
of
cycloning
is
viewed
as
the
most
appropriate method for
disposal of the tailings
material. Track mounted
cyclone units (Figure
15.4) are
used with eight cyclone units connected to the tailings
pipeline system. The TSF was originally designed
by Knight Piésold. Operational activities are currently
under contract by Fraser Alexander.
Immediately
adjacent
and
to
the
south
of
the
Brakpan/Withok
TSF
footprint
lies
the
former
cleared
footprint of an
area licensed for
tailings storage,
spanning an
approximate 400 hectares.
This area, on
which
a
large
portion
of
the
Withok
compartment
stood,
was
retreated
and
cleared
by
the
former
owners
of
Ergo.
Ergo
intends
to
redeposit
residue
tailings
onto
this
compartment
and
has
initiated
a
process
to
obtain
regulatory
approval
for
the
final
design
of
the
Brakpan/Withok
TSF.
The
Brakpan/Withok
TSF final
design is
the engineering
design that
ultimately brings
the tailings
deposition
facility
to
its
finality
in
terms
of
extent,
operation,
rehabilitation
and
management.
The
implemented
final
design
would
result
in
alignments
with
the
Global
Industry
Standard
on
Tailings
Management
(GISTM)
and
regulatory
bodies,
increase
deposition
capacity,
improve
operation/management
and
bring about the sustainable closure of the facility.
The Brakpan/Withok TSF will provide sufficient storage
capacity
to
support
Ergo’s
19-year
LoM
plan.
Ultimately,
when
the
Withok
compartment
of
the
TSF
reaches a suitable height, it will merge with the Brakpan
compartment of the TSF.
The Brakpan/Withok
TSF as of
30 June 2022
has a capacity
of 250.4Mt.
Once regulatory
approvals are
received for its final life design, the TSF will have will
have a joint capacity of over 930Mt.
Technical Report Summary of the material Tailings
Storage Facilities
186
Figure 15.3:
Brakpan/Withok TSF
Source: DRDGOLD, 2022
Figure 15.4:
Placement of Tailings Material at Brakpan/Withok TSF
Technical Report Summary of the material Tailings
Storage Facilities
187
Source: DRDGOLD, 2022
15.8
Conclusion
The
QP
is
of
the
opinion
that
all
significant
infrastructure
and
logistical
requirements
have
been
considered.
It
is
notable
that
Ergo
has
been
operating
for
more
than
20
years
and
has
a
very
good
understanding of infrastructural and logistical requirements.
Technical Report Summary of the material Tailings
Storage Facilities
188
16
Market Studies
16.1
Markets
All gold
produced
is delivered
to
the
Rand
Refinery
for refining
with no
restrictions
on the
quantity
or
time
frame.
DRDGOLD
has
a
long-standing
agreement
with
Rand
Refinery
in
terms
of
which
Rand
Refinery accounts to Ergo at the prevailing spot price. When
applying the 30 June 2022 spot exchange
rate
(ZAR16.29/USD)
to
the
associated
gold
price
of
USD1,819.06/oz
Au,
a
real
gold
price
of
ZAR952,721.20/kg is achieved.
Gold is
a precious
metal, refined
and sold
as bullion
on the
international market.
Aside from
the gold
holdings of
central banks,
current uses
of gold
include jewelry,
private investment,
dentistry, medicine
and technology (Table 16.2).
Table 16.1:
Above Ground Gold Stocks in 2021
Description
Quantity
(t)
Contribution
(%)
Jewelry
94,464.0
46%
Private Investment
45,456.0
22%
Bank Holdings
34,592.3
17%
Other
30,726.0
15%
Source: GoldHub, 2022
The largest use of gold is in jewelry, accounting for approximately
46% of the above-ground gold. Gold
does not follow
the usual supply
and demand logic
because it is virtually
indestructible and can
easily
be recycled. In
addition, gold stored
in the vaults of
banks is relatively
illiquid and subject to
the vagaries
of global economies. These characteristics of the gold market make it challenging
to forecast the gold
price.
16.2
Gold Price
The
gold
price
increased
in
2020
due
to
uncertainties
related
to
the
outbreak
of
Covid-19.
It
then
declined
to
a
spot
price
of
~ZAR945,295/kg
(i.e.,
USD1,806.89/oz
at
ZAR16.27/USD)
as
at
30 June 2022 (Graph 1).
Technical Report Summary of the material Tailings
Storage Facilities
189
800
1,000
1,200
1,400
1,600
1,800
2,000
2,200
2,400
Jun-17
Jun-18
Jun-19
Jun-20
Jun-21
Jun-22
Gold Price (USD/oz)
Gold's Monthly Closing Price
Trendline
Upper and Lower Standard Deviation Bands
10
11
12
13
14
15
16
17
18
19
Jun-17
Jun-18
Jun-19
Jun-20
Jun-21
Jun-22
Exchange Rate (ZAR/USD)
Monthly Closing USD/ZAR Rate
Trendline
Upper and Lower Standard Deviation Bands
Graph 1: Gold Price Historical Trendline
Source: Sound Mining, 2022
The linear trendline indicates robust gold price potential
over the longer-term.
16.3
Exchange Rate Trends
The ZAR to USD exchange rate saw record breaking highs in
the second quarter of 2020 (ZAR19.35/USD)
but has subsequently
dropped back
to ZAR16.27/USD as
at 30 June
2022. A factor
in the deterioration
of the local currency in 2020 was the lockdowns and
economic volatility brought on by Covid-19.
The spot
exchange rate of
ZAR16.27/USD compares well
with the
six-year historical trendline
as displayed
in Graph 2.
Graph 2: Exchange Rate Historical Trendline
Source: Sound Mining, 2022
Technical Report Summary of the material Tailings
Storage Facilities
190
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
Quantity (t)
Year
Various service providers
and financial institutions are
consulted to determine consensus
forecasts of the
gold price (Table 16.2).
Table 16.2:
Long Term Consensus Forecasts in Nominal Terms
Description
Year 1
(FY2023)
Year 2
(FY2024)
Year 3
(FY2025)
Year 4
(FY2026)
Year 5
(LT)
USD/oz
1,823
1,799
1,751
1,724
1,496
ZAR/USD
15.60
15.74
15.77
15.79
15.20
ZAR Price/kg
914,294
910,051
888,083
875,474
731,081
Source: Sound Mining, 2022
The economic assessment
for the Mineral Reserve
estimate relies on a real
price of ZAR914,294/kg (i.e.,
USD1,823/oz
at
ZAR15.60/USD)
as
of
30
June
2022
terms
as
provided
by
DRDGOLD.
The
QP
has
considered
the
consensus
forecasts
supplied
by
DRDGOLD
against
linear
trends
in
the
demand
and
supply of gold
as recorded
over the period
from 2012 to
2021 to examine
whether these forecasts
are
reasonable.
16.4
Global Demand
Graph 3 reveals a gradual reduction in demand (~14.2%)
over the past ten years (2012 to 2021).
Graph 3: Global Gold Demand from 2012 to 2021
Source: GoldHub, 2022
Technical Report Summary of the material Tailings
Storage Facilities
191
4,100
4,200
4,300
4,400
4,500
4,600
4,700
4,800
4,900
5,000
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
Quantity (t)
Year
16.5
Global Supply
The global gold supply from mining and recycling activities over the same period is presented in
Graph
4.
Graph 4: Global Gold Supply from 2012 to 2021
Source: GoldHub, 2022
While
the
graph
suggests
an
overall
upward
trend
from
2012
to
2021
(~2.6%),
the
supply
generally
levelled out over the past five
years. The supply from mining
satisfied some 76% of the demand in
2021,
with the balance met by recycled gold.
Gold supply
from mining
increased
by
approximately
106t during
2021 (3,582t)
when
compared
with
2020 (3,476t) despite
an overall drop
in supply since
2019 (GoldHub, 2022).
Below are the
top ten gold
producing countries in 2021 (Table 16.3).
Table 16.3:
Global Gold Production
Rank
Country
Production
(t)
2016
2017
2018
2019
2020
2021
1
China
464
429
404
383
368
332
2
Russia
262
281
295
330
331
331
3
Australia
288
293
313
325
328
315
4
Canada
163
171
189
183
171
193
5
United States of America
229
236
225
200
190
187
6
Ghana
131
133
149
142
139
129
7
Peru
166
167
163
143
98
127
8
Mexico
131
120
118
109
102
125
9
Indonesia
118
118
153
92
101
118
10
South Africa
163
154
128
111
99
114
Source: GoldHub, 2022
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16.6
Concluding Comments
The
QP
notes
a
short-term
up-tick
despite
the
long-term
reduction
in
demand
together
with
an
essentially constant
supply over
the past
five years.
These trends
are not
inconsistent with
the forecast
price trend
in Table
16.3. The
QP is
satisfied that
a real
30 June
2022 gold
price of
ZAR914,294/kg
is a
reasonable
assumption for examining the economic viability of the Mineral
Reserve estimate.
Technical Report Summary of the material Tailings
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17
Environmental Studies
17.1
Results of Environmental Studies
An
Environmental
Impact
Assessment
(EIA)
has
been
conducted
over
the
Ergo
operation
with
the
findings
of
the
EIA
showing
that
the
operation
would
result
in
certain
negative
impacts
during
the
operational phase to the environment, however, none of the specialist
studies objected to the project.
During
the
mining
operations,
negative
impacts
are
largely
Moderate
to
Insignificant,
and
after
interventions the
impacts are
mitigated to
a Low
significance. During
the decommissioning
and post-
decommissioning
phases,
most
of
the
impacts
will
be
positive
as
the
historical
TSFs
and
associated
environmental impacts of the TSFs are removed.
Social and
community interaction
remains a
key focus
for Ergo.
Stakeholder
engagement is
reported
annually
with
the
SLP
compliant
and
filed
with
the
proper
authorities.
Ergo
appears
to
have
good
relations with surrounding communities and engages
proactively.
The QP
is unaware
of any
material flaws
in terms
Ergo’s social
license to
operate, however,
it is
noted
that in the current South African socio-political issues remain
a risk and require constant monitoring.
Rehabilitation
will
be
carried
out
once
the
reclamation
of
individual
TSF
are
completed,
with
rehabilitation returning the disturbed land to as close to its
original landscape as possible.
The principles for proper rehabilitation are:
●
preparing a comprehensive rehabilitation plan prior to the commencement of any activities on
site;
●
stormwater management must be in place at the site prior
to commencing with any activities;
●
landform design (e.g., shaping, re-grassing, etc.);
●
maintenance management and eradication of invader
species;
●
a plan on how waste will be managed on site; and
●
an emergency preparedness/response plan.
The objective of the site
rehabilitation (in accordance
with the NEMA EIA Regulations
of 2014) must be
measurable, practical and be feasible to implement through:
●
providing the vision, objectives, targets and criteria
for final rehabilitation of the project;
●
outlining the principles for rehabilitation;
●
explaining the
risk assessment
approach and
outcomes and
link decommissioning
activities to
risk;
●
rehabilitation detailing the decommissioning and rehabilitation
actions that clearly indicate the
measures that
will be
taken to
mitigate and/ or
manage identified risks
and describing the
nature
of residual risks that will need to be monitored and managed
post decommissioning;
●
identifying knowledge gaps and how these will be addressed
and filled; and
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●
outlining monitoring, auditing and reporting requirements.
17.2
Requirements for Tailings Disposal, Site Monitoring and Water Management
The general description of the Brakpan/Withok TSF is covered
in Item 15.
17.2.1
Site Monitoring
Site
monitoring
provides
information
on
whether
rehabilitation
methods
employed
are
functioning
correctly or not. The purpose of monitoring is to ensure that the objectives of the rehabilitation program
are met, and that the progressive rehabilitation process is followed
as planned during the LoM.
The
post
closure
monitoring
period
will
begin
once
scheduled
decommissioning
and
rehabilitation
activities for the sites have been completed. The duration of post closure monitoring
will be determined
based on environmental performance
and until it can
be demonstrated that the
rehabilitation work has
achieved the agreed outcomes;
however, at present, it
has been assumed that
post closure monitoring
will not continue
for more than
five years. It
is important that
the data obtained
during monitoring is
used
to gauge the success of rehabilitation. Negative monitoring findings should be
clearly linked to specific
corrective actions.
The following aspects should be monitored during the post-closure
phase.
17.2.2
Water Management
The quality
of groundwater
and
surface
water at
the
various
sites will
be
monitored
quarterly
for five
years
post
closure,
except
for
the
Knights
Mining
Right
which
requires
30
years
monitoring
at
certain
monitoring points as per the approved WULs, to ensure
compliance of the various constituents with the
standards. Samples should be analyzed for particulate and soluble contaminants. Water monitoring will
be taking place at 76 different locations.
17.2.3
Vegetation Monitoring
The following vegetation monitoring is recommended:
●
vegetation cover;
●
species composition;
●
erosion; and
●
alien invasive plants.
17.2.4
Vegetation Maintenance
Vegetation maintenance will specifically focus on fertilizing the rehabilitated areas annually if required,
controlling
alien
invasive plants
where
needed
and
general
maintenance
such as
in-filling
of erosion
gullies. In the case of erosion, the cause should be identified,
and rectified.
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17.2.5
Water Monitoring
Currently, 66% of
all process water
make-up at Ergo
is drawn from
water returned from
the Brakpan as
shown in Table 17.1.
Table 17.1:
Ergo Water Consumption
Description
Total Consumption 2022
Total Consumption 2021
Ml
%
Ml
%
Potable Water Sources Externally
2,460
9
2,813
11
Rondebult Waste Water
27
-
46
-
Surface Water Extracted
4691
18
4,210
17
Water Recycled in Process
16,302
62
17,233
66
TCTA Water (AMD)
2,907
11
1,683
6
Total Water Used
26,387
100
25,985
100
Source: DRDGOLD, 2022
17.2.6
Legal and Permitting
Item 3 of the TRS (Table 3.2) discusses the Mining
Rights and Prospecting Rights details for Ergo’s and the
status thereof.
Ergo’s EMP encompasses all the activities
of Ergo’s operations and assesses
the environmental impacts
of mining
at reclamation
sites, plants
and
TSFs. It
also outlines
the
closure
process, including
financial
provisions.
There are currently no legal challenges to Ergo’s title
to its reserves other than those discussed below.
The QPs are aware of two issues that could impact on Ergo’s current mining rights or mining
operations.
Grootvlei Complex:
Ergo has a
Mining Right over Grootvlei
TSF 6L14 via Mining
Right GP158MR and
has
submitted a renewal application of
its Prospecting Rights over
Grootvlei TSFs 6L16, 6L17
and 6L17A to the
DMRE,
which
application
is
pending.
During
the
2022
financial
year,
an
external
party
raised
a
conflicting claim
of common
law ownership
of TSFs
6L16, 6L17
and 6L17A.
Although the
claim was
on
common law
ownership
and no
challenge
has been
brough against
the Prospecting
Rights
over the
dumps, the
Grootvlei Complex
has been
excluded from
the Mineral
Reserves statement
and the
LoM
plan. However, the Grootvlei Complex has been included in the Mineral Resources statement as Ergo is
of the opinion that the Prospecting Rights will be renewed.
Marievale Complex:
Ergo acquired
the Marievale
TSFs 7L5,
7L6 and
7L7 in
terms of
a written
notarially
executed
deed
of
sale
during
2019
and
took
possession
of
the
TSFs
on
8
April
2019.
It
has
since
also
obtained the requisite
NEMA regulatory approvals
to retreat these
TSFs. During the
2022 financial year,
the owner of the
land on which
7L5, 7L6 and a
portion of 7L7
are situated, an
estimated 36,524t out
of
the
total
54,114t
comprising
the
Marievale
Complex,
notified
Ergo
that
in
its
view,
the
said
TSFs
had
acceded to the land,
and that it had
become the owner of the
TSF. Ergo disputes the claim
of legal title
and the matter is to be referred to arbitration. All ownership requirements were met when the TSFs were
purchased
by
Ergo
and
therefore
these
TSFs
are
still
included
in
the
LoM
plan
and
Mineral
Reserves.
Whilst Ergo has
received confident legal advice
of the merits
of its claim,
in the event that
the arbitration
goes against Ergo, its Mineral Reserves will reduce by 35.52Mt (0.35Moz at 0.29g/t). In so much as it then
enters into
a commercial
arrangement with
the landowner,
the financial
benefit of
this portion
of the
Marievale Complex will be reduced by whatever benefit
is agreed to in favor of the land-owner.
Technical Report Summary of the material Tailings
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Ergo has
submitted a
renewal application
to the DMRE
for the
Prospecting Rights
it holds
over the
7L4
TSF as described more fully under Item 3.6.
17.3
Plan Negotiations, or Agreements with Local Individuals or Groups
Social and
community interaction
remains a
key focus
for Ergo.
Stakeholder
engagement is
reported
annually against the SLP and any complaint is filed with
the proper authorities.
The QP is unaware
of any material
flaws of Ergo’s social
license to operate. However,
it is noted that
in
the current
South African
political environment,
social and
community issues
always remain
a risk
and
require constant monitoring.
The five-year SLP was
submitted by Ergo in
terms of the requirements
of the MPRDA. The development,
submission and
implementation of
an SLP
is a
requirement of
the MPRDA
and the
right to
mine. Table
17.2 indicates
the budget
for the
2018
to 2022
SLP, noting
that the
SLP plan
is conducted
in five-year
segments.
The SLP covers three key elements:
●
Human
Resource
Development
(HRD)
:
which
focuses
on
the
empowerment
of
historically
disadvantaged
South Africans
to progress
to higher
career
levels
within
the
industry.
Ergo
has
various
programs
to
address
this
aspect,
including
skills
development
programs,
career
progression and mentorship employment equity targets
;
●
Local Economic
Development
(LED):
which
focuses
on
the
upliftment
of
both the
surrounding
(affected)
and
labor-providing
communities.
Ergo
has
four
projects,
one
agricultural
development,
a
sewing
project
and
two
projects
to
upgrade
facilities
at
primary
schools.
A
ZAR10 million budget is allocated to these LED projects
;
and
●
Program
for
Management
of
Downscaling
and
Retrenchment:
which
focuses
on
minimizing
negative impact
due
to
either job
losses
through
retrenchment
and
mine
closure in
the long-
term.
Table 17.2:
SLP Financial Provision Summary
Description
2018
2019
2020
2021
2022
Total
(ZAR million)
HRD Total
7.08
7.53
5.69
5.91
7.08
33.29
LED Total
3.40
5.80
2.60
2.20
1.50
15.50
Downscaling Retrenchment
13.00*
SLP Budget
10.48
13.33
8.29
8.11
8.58
61.79
Source: DRDGOLD, 2022
Note: *This amount has already been accrued and
is available for reskilling should the mine prematurely
be forced to close.
17.4
Mine Closure Plans Remediation Plans, and Associated Costs
In accordance
with South African
mining legislation,
all mining
companies are required
to rehabilitate
the land on which
they work to
a determined standard for alternative use.
Ergo has spent ZAR198 million
on various rehabilitation activities in the three years between 2020
and 2022.
A community consortium,
consisting of
nine local companies
that represent areas
including Langlaagte,
Diepkloof,
Meadowlands,
Orlando
West,
Orlando
East,
Riverlea,
Pennyville
and
Ormonde,
has
been
Technical Report Summary of the material Tailings
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established to
conduct certain
rehabilitation work
for Ergo
as part
of its
small enterprise
development
initiatives.
It currently
employs 27
community members
from the
abovementioned
areas. Their
current
project entails the establishment of
new side slope vegetation on
the Crown TSFs and to
irrigate until the
vegetation is self-sustainable.
Ergo is on track to complete this vegetation program
by 2026.
In
2016,
a
decision
was
taken
to
complete
the
recovery
of
mine
waste
materials
from
a
number
of
legacy
reclamation
sites
and
to
close
the
Crown
plant.
The
clean-up
of
the
legacy
sites
has
proven
difficult
and
costly
and
requires
the
use
of
earthmoving
equipment
to
mechanically
lift
and
move
residual material.
Steady progress is being made on the clean-up and closure
of these legacy sites.
As clean-up work on former
reclamation sites is completed, applications
are submitted to the National
Nuclear
Regulator
(NNR)
for
land
clearance
certificates.
In
2019,
Ergo
received
land
clearance
certificates for an area
covering approximately 135.5ha
from NNR, releasing
land located close to
the
Benoni central business district for development.
In 2019, applications were lodged with the NNR in respect of 136ha of rehabilitated land for clearance.
In 2020,
applications were
lodged for
a further
27ha of
rehabilitated land
,
in 2021,
for a
further 87.6ha
and in 2022, for a further 23.6ha.
Ergo’s decommissioning and restoration liabilities
are funded by
a combination of funds
that have been
set aside for environmental rehabilitation. ZAR132.7 million is currently held in the Guardrisk Cell Captive
under
a
ring-fenced
environmental
insurance
policy.
Further
environmental
guarantees
of
ZAR377.8
million
have
been
issued
by
Guardrisk
Insurance
Company
Limited
to
the
DMRE.
In
total,
Ergo
has
ZAR510.5 million in environmental rehabilitation
and closure cover.
The calculated costs for rehabilitation and closure of the Ergo Operations estimated by Digby Wells are
ZAR639
million
(Table
17.3).
Ergo
systematically
audits
and
monitors
progress
on
rehabilitation
and
closure
and
adjusts
its
provision
accordingly.
Required
audits
are
undertaken
and
submitted
to
the
DMRE annually.
Table 17.3:
Ergo Rehabilitation Financial Provision Summary
Area and Mining Right
Closure Cost 2022
(ZAR)
CMR - GP186MR
11,845,711
Crown - GP184MR
125,160,690
City Deep - GP185MR
41,802,525
Knights - GP187MR
46,318,600
ERPM - GP150 and 151MR
10,240,493
Ergo - GP158MR
403,565,361
Total (excluding VAT)
638,933,381
Source: Digby Wells, 2022
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17.5
QP Statement on the Environmental Studies, Permitting, Plans,
Negotiations, with Local
Individuals or Groups
The QP is satisfied that all
material issues relating to Environmental,
Social and Governance have
been
addressed in this document.
The above statement
is borne out
by the fact
that Ergo incurred
no fines of
monetary value or
significant
non-monetary sanctions for non-compliance with environmental laws and regulations were imposed
in
the past four years (2019, 2020, 2021 and 2022).
The QP
finds the
funding
mechanism
appropriate
for mine
rehabilitation
and mine
closure, but
notes
that
there
is
a
shortfall
between
the
reclamation
funding
and
the
July
2022
Digby
Wells
closure
cost
estimate.
Technical Report Summary of the material Tailings
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18
Capital and Operation Costs
The capital expenditure and operating costs provided take cognizance of the requirements
to support
the
LoM
plan.
The
capital
expenditure
takes
into
account
the
ongoing
requirements
of
starting
new
operating sites as current
TSFs Mineral Reserves are
depleted. This capital expenditure
schedule is based
on the
LoM production schedule
with the
capital expenditure based
on mining and
engineering designs
conducted to a PFS level of accuracy (i.e., +/-25%) with a maximum
level of contingency of 15% being
applied.
The operating
costs support
the planned
LoM production
profile taking
into consideration whether
slimes
or
sand
material
is
mined
and
the
method
and
distance
in
which
the
mineralized
material
is
transported(i.e., pumped
or trucked). Operating
costs are activity-based
costs accounting for
surface
mining costs (extraction
and transportation); processing
costs (including tailings
disposal costs), cost
of
maintaining
key
mine
infrastructure
and
general
and
administrative
costs.
The
estimate
of
operating
costs are based on historical operating cost data, which is well understood as Ergo is
a well-established
mining operation.
Operating costs
are estimated
to at least
a PFS
level of
accuracy (i.e.,
+/-25%)
with
no contingency applied due to the understanding
of the cost to mine and process the RoM material
.
18.1
Capital Expenditure
A total capital
of ZAR3.22 billion
is scheduled
to support the
Ergo LoM
plan.
The breakdown
of capital
expenditure indicates
the majority
of the
capital, ZAR3.14
billion,
is allocated
to the
Ergo Section
over
the duration of the LoM plan with an additional ZAR81.9 million allocated in
2022 for the City Section.
As
the mining at the Knights
Section is completed in 2024 there is no allocation
of capital.
The
capital
expenditure
summary
as
proposed
in
the
30
June
2022
LoM
plan
is
presented
in
Table
18.1.
The
level
of
accuracy
for
the
capital
expenditure
is
to
at
least
a
PFS
level
of
accuracy
(i.e., +/-25%) with a maximum level of contingency
of 15%.
Table 18.1:
Capital Expenditure Summary
Area
Budgeted Capital
Expenditure
(ZAR)
Ergo Section
3,137,603,000
City Section
81,923,000
Knights Section
0
Total (excluding VAT)
3,219,526,000
Source: DRDGOLD, 2022
18.1.1
Ergo Section Capital Expenditure
This
section
depicts
the
capital
expenditure
estimate
for
the
Ergo
Section.
Table
18.2
indicates
the
Rooikraal capital expenditure estimate planned in January
2022.
Table 18.2:
Rooikraal Capital Expenditure Estimate
Discipline
Capital Expenditure
(ZAR)
Consultancies
324,000
Civil
15,100,835
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Structural Steel
14,591,639
Mechanical
18,783,480
Piping
99,680,396
Electrical
28,471,978
Instrumentation
1,599,218
Security
415,634
Other
2,824,000
Total
181,791,181
Source: DRDGOLD, 2022
Note: ZAR 91.759 million spent in 2021/22 financial
year
Table 18.3
indicate the capital
expenditure estimate for
the Marievale pump
station and
total Marievale
capital expenditure estimate respectively.
Table 18.3:
Marievale Capital Pump Stations
Area
Budgeted Capital
Expenditure
(ZAR)
Consultants
294,000
Civil engineering
29,793,240
Structural steelwork
30,583,013
Mechanical
36,020,706
Electrical
66,507,688
Instrumentation
4,471,908
Security
1,525,297
Other
7,568,000
Total (excluding VAT)
176,763,853
Source: DRDGOLD, 2022
Table 18.4:
Marievale Total Capital Expenditure Summary
Area
Budgeted Capital
Expenditure
(ZAR)
Pump Station
176,763,853
Slurry Pipeline
65,628,130
Water Pipeline
56,328,874
Water Transfer
41,343,778
total (excluding VAT)
345,590,778
Source: DRDGOLD, 2022
Table 18.5
shows the
estimated capital
expenditure for
the Daggafontein
pump station,
inclusive of
a
ZAR4.6 million contingency (4.2%). Table
18.6 indicates the Daggafontein capital expenditure summary.
Table 18.5:
Daggafontein Capital Pump Stations
Description
Budgeted Capital
Expenditure
(ZAR)
Consultants
294,000
Civil Engineering
17,611,703
Structural Steelwork
18,279,748
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Mechanical
20,300,199
Electrical
41,446,040
Instrumentation
4,471,908
Security
415,634
Other
7,568,000
Total (excluding VAT)
110,387,234
Source: DRDGOLD, 2022
Table 18.6:
Daggafontein Capital Expenditure Summary
Area
Budgeted Capital
Expenditure
(ZAR)
Pump Stations
110,387,234
Slurry Pipeline
36,981,310
Water Pipeline
33,161,400
Daggafontein Plant Upgrades
86,149,055
Total (excluding VAT)
266,679,000
Source: DRDGOLD, 2022
Table 18.7shows the non-material TSF Capital Expenditure for
the Ergo Section.
Table 18.7:
Non-material TSF Capital Expenditure for the Ergo
Section
Area
Budgeted Capital
Expenditure
(ZAR)
4L14
50,157,000
7L15
60,000,000
4L39
69,927,000
5L27
59,852,000
Sustaining
1
and Small Capital Projects
837,085,000
Total (excluding VAT)
1,077,021,000
Source: DRDGOLD, 2022
Note:
1.
Sustaining capital of ZAR30 million between years 3 to 18 (ZAR480 million); ZAR221.4 million
and ZAR105.6 million allocated in year 1 and
year 2 to complete numerous small capital programs
The Withok compartment design is based on
upstream cyclone system and a scavenger well system
for
environmental
containment.
The
Brakpan/Withok
TSF
has
been
digitally
modelled
which
model
has
been
used
to
inform
the
various
quantities
of
the
various
infrastructure
aspects.
The
capital
costs
to
implement
the
Withok
compartment
has
been
estimated
upon
typical
contractor
tender
methodologies
by
Beric
Robinson
Tailings
(Proprietary)
Limited.
Table
18.8
indicates
the
capital
expenditure budget for the proposed Withok compartment
.
The Withok compartment design work has
been conducted to a PFS level of accuracy with
a 15% contingency applied to the capital estimate.
Table 18.8:
Withok Compartment Capital Expenditure
Area
Budgeted Capital
Expenditure
(ZAR)
Construction Contract
456,056,963
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Material Supply
76,009,494
Engineering Design and Oversight
3,648,456
Scavenger Boreholes
12,161,519
Pumps, Power Reticulation and Other
60,807,595
Sub-total
608,684,026
Contingency 14%
91,302,604
Total (excluding VAT)
699,986,630
Source: DRDGOLD, 2022
The capital budget for the solar power project is shown
in Table 18.9.
Table 18.9:
Solar Power Project Capital Estimate
Area
Budgeted Capital
Expenditure
(ZAR)
Solar MW Works
69,579,000
Solar 20MW
338,084,000
Solar 88kV (15% contingency)
239,660,000
Total (excluding VAT)
646,323,000
Source: DRDGOLD, 2022
18.1.2
City Capital Expenditure
A capital of ZAR81.9 million has been allocated to the City
section in 2022 (Table 18.10).
Table 18.10:
City Total Capital Expenditure Summary
Area
Budgeted Capital
Expenditure
(ZAR)
4/L/4 TSF
19,527,000
Valley Silts
62,396,000
Total (excluding VAT)
81,923,000
Source: DRDGOLD, 2022
18.1.3
Knights Capital Expenditure
Due to the short life of the Knights Section,
no capital expenditure has been planned
or budgeted.
18.1.4
QP commentary
The QP associates
a low risk
to the engineering
capital expenditure
for the mining
associated projects
as the design and
construction of pump stations
and pipelines have
been conducted numerous times
by
Ergo.
The QP
notes
the
level
of accuracy
for
the
capital
expenditure
estimates
are
to a
PFS level
accuracy (i.e.,
+/-25%). Contingency
varies between
0% to
15% with
contingency typically
applied to
civil work, structural steelwork and
electrical and instrumentation. In
no case is the contingency
above
15%.
The QP is
of the opinion
that the risk
associated with the Withok
compartment capital estimate and
solar
plant and storage facility is Low to Medium and typical
of a PFS level of accuracy (i.e., +/-25%).
Technical Report Summary of the material Tailings
Storage Facilities
203
18.2
Operating Costs
Mining related operating costs are
assigned to the Ergo processing plant
and the mining of the various
TSFs. A different operational cost is applied to each deposit, depending on its composition, proximity to
the processing plant and the
reclamation method. Sand dumps have a
higher cost than slimes, as sand
must be milled down to 80% less than 75µm while the
slime can be treated in the CIL tanks directly.
Mining related operating
costs are assigned
to the planned
TSFs to be
mined and the
Ergo processing
plant. The planned average
operating cost for the Ergo
19-year LoM plan is estimated
at a PFS level of
accuracy
(i.e.,
+/-25%)
with
a
maximum
level
of
contingency
of
15%
with
a
total
working
cost
of
ZAR90.86/t (Table 18.11).
Table 18.11:
Average LoM Operating Cost for Ergo
Operating Cost
Average LoM
Operating Cost
(ZAR 000’s)
Labor
375,733
Consumables
663,822
Electricity
81,735
Water
28,557
Contractors
350,715
Other
262,710
Sub-total Cash Cost
1,863,272
Rehabilitation Cost
25,349
Other Operation Cost
24,572
Retrenchment Cost
6,215
Corporate Cost
42,916
Sub-total Other Cost
99,052
Total Working Cost
1,962,324
Source: The RVN Group, 2022
The
development
of
the
annual
operating
costs
is
based
on
historical
cost
data
as
Ergo
has
been
operational for numerous years. The
QP associates a Low
risk with many of
the operating costs, however
a Medium
risk is
associated
with consumables,
electricity
and water
due
to the
volatile nature
of the
market of these items. Ergo is attempting to mitigate the volatility with the installation of the solar power
project and reuse of water where possible. Refer to Item 19.3
for more details on risk.
Technical Report Summary of the material Tailings
Storage Facilities
204
19
Economic Analysis
19.1
Economic Analysis
The 30
June 2022
19-year LoM
plan, which
is the
basis of
the Mineral
Reserve, is
scheduled to
mine a
total
of
410.33Mt
at
0.28g/t
Au
and
produce
50,658kg
of
gold
over
the
same
period.
The
economic
analysis is based on a LoM plan that is designed to a PFS level of accuracy (i.e., +/-25%). The economic
analysis
conducted
by
the
QP
indicates
a
net
present
value
(NPV)
of
ZAR2.2
billion
after
capital
expenditure and
taxation
utilizing a
discount rate
of 9.48%
(real terms).
As the
Ergo operations
are an
on-going with an annual positive cashflow, the internal rate of return (IRR) and payback period are not
applicable.
Figure 19.1:
Ergo LoM Production Tonnage
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings
Storage Facilities
205
Figure 19.2:
Ergo LoM Gold Production
Source: The RVN Group, 2022
Table 19.1 presents the
Ergo cashflow model over
the 19-year LoM Plan.
The NPV has been
calculated
by
discounting
the
positive
cashflows
at
the
appropriate
rate
and
subtracting
the
required
capital
expenditure. The QP has made the assumptions listed below to derive a realistic base case operational
cashflow model:
●
the
production
schedule
is
sourced
from
the
Ergo
LoM
plan.
The
mining
tonnage
schedule
is
shown in Figure 19.1, which varies between 23.0Mtpa
and 18.2Mtpa;
●
plant feed grade as per the LoM schedule (Figure 19.2)
with an average grade of 0.28g/t Au;
●
the average metallurgical recovery over the LoM schedule
is 40.9%;
●
total
working
costs
estimated
at
ZAR90.86/t
RoM
are
inclusive
of
mining,
metallurgical
and
general and administration costs (working costs);
●
the gold market
price is
set at ZAR914,294/kg
(see Item
16 for further
information for
gold price
in USD/oz and exchange rate);
●
capital expenditure of ZAR3.219 billion is inclusive of contingency
;
●
no salvage value of assets has been assumed;
●
a tax rate of 27%;
●
a discount rate of 9.48% in real (no inflation) terms;
●
no
royalty
payment
is
applicable
to
Ergo,
as
the
operation
is
not
subject
to
royalties
on
the
retreatment of TSFs;
●
capital expenditure was fully written-off against operating
profit, with no time constraint; and
Technical Report Summary of the material Tailings
Storage Facilities
206
●
no escalation
or inflationary
effects have
been included
in the
economic evaluation,
which is
based on constant money value (real terms).
The NPV of the Ergo
LoM plan as at 30
June 2022
was calculated at ZAR2.2
billion at a discount
rate of
9.48% as shown in Table 19.1
.
Technical Report Summary of the material Tailings Storage
Facilities
207
Table 19.1:
Economic Analysis
Source: The RVN Group, 2022
Technical Report Summary of the material Tailings
Storage Facilities
208
19.2
Sensitivity Analysis
The sensitivity analysis of the Ergo financial model
that varies revenue (price and grade); operating cost
and capital expenditure at 5% increments above
and below the base case is shown in Figure
19.3.
The
analysis indicates that the Ergo operations are very sensitive to revenue parameters such as gold price,
grade, and recovery.
In addition, the LoM
plan is also very
sensitive to changes in
operating costs. The
sensitivity
indicates
that
the
LoM
plan
is not
as
sensitive
to capital
and
therefore
capital
expenditure
should be considered
if the expenditure
will result
in reducing operating
cost or increase
revenue. The
sensitivity
indicates
that
achievement
of
the
LoM
plan
in
terms
of
tonnage
is
critical
in
realizing
the
planned operating
costs and
being able
to mine
at the
planned cut-off
grade. The
QP is
unaware of
any capital
expenditures, that
if delayed,
would materially
affect the
LoM plan
or cashflow.
The QP
is
of the opinion that no extremely weather conditions will materially
impact on the capital development
program.
Figure 19.3:
Sensitivity Analysis
Source: The RVN Group, 2022
19.3
Risk Assessment
The following
highlights show
the key
risks that
Ergo has
identified as
critical to
their operations,
as well as comments
on mitigation of these risks.
19.3.1
Rising Electricity Prices and Eskom Supply Distribution
The mining industry is a dominant
consumer of electricity, consuming approximately 30% of the
national
electricity supply. The processing plants operate on
a “24/7/365”
basis and continuous electricity supply
is paramount to achieving a stable plant with enhanced
efficiencies.
Eskom
remains
the
biggest
systemic
risk
to
the
sustainability
of
the
South
African
economy.
On
28 July 2020, a
court judgment was given against the National
Energy Regulator of South Africa
(NERSA)
and allowed for Eskom to increase its
tariffs from the original 5.22% on
1 April 2021 to approximately 15%.
An increase
of 14.59%
was
approved
for
the 202
1
to 2022
municipal
tariff after
Eskom
applied
for
an
Technical Report Summary of the material Tailings
Storage Facilities
209
electricity
price
increase
of
20.5%.
In
February
2022,
NERSA
allowed
for
an
increase
of
9.6%
in
the
standard electricity tariff as implemented in April 2022.
Ergo has adopted a two-staged approach to the risks associated
with electricity supply.
Firstly,
Ergo
has
had
to
install
extensive
back-up
systems
to
counteract
the
impact
of
unscheduled
interruptions in the power supply. Although Ergo is unable
to maintain full production during black-outs,
back-up generator sets ensure that the
processing plants remain
in motion and that the circuits
do not
choke or become
blocked through the
settlement of solids
in the slurry.
This enables the
immediate start-
up of production once the power is restored.
At the
Brakpan/Withok
TSF, the
back-up
capacity
is sufficient
to ensure
that
deposition can
continue
uninterrupted, thus
there is
no interference
with the
processing plant
operations (i.e.,
if the
deposition
system comes to a halt, then the entire operation will stop). From a safety perspective, it is also
essential
that the
water balance
on the
TSF pumping
operations remain
under control
to ensure
that water
on
the Brakpan/Withok TSF remains within the stated factors
of safety.
The second
important
strategic
consideration
regarding
electricity
supply is
to address
the impact
of
escalating
electricity
costs.
Ergo
continues
to
investigate
ways
of
reducing
the
impact
of
price
increases. Power storage and the pricing policy of Eskom to charge different rates during peak
and off-
peak periods
appear to
be the
most likely
near-term solutions
in this
regard. Charging
power storage
units during
these periods
and then
drawing them
down during
peak hours
to avoid
peak rates,
may
well in the long-term, provide a financially feasible model
in this regard.
Ergo
has
obtained
regulatory
approvals
for
the
development
of
a
solar
photovoltaic
and
battery
storage
facility
which
will
be
located
adjacent
to
the
Ergo
processing
plant.
Ergo
has
approved
ZAR646.3 million to develop the first phase of the solar
energy project.
19.3.2
Tailings Storage Facility Capacity
Ergo is a
volume-driven business.
As a result,
Ergo needs to
ensure that there
is sufficient capacity
in its
TSFs
to
deposit
material
after
processing
and
extracting
gold
in
the
plant.
Additional
tailings
storage
capacity is required
in the
medium-term to continue
operating at
current levels. This
additional capacity
will come from the Brakpan/Withok TSF, adjacent to the Brakpan
TSF. Ergo has allocated ZAR700 million
for the
implementation
of the
Brakpan/Withok
TSF final
life
design.
These is
a risk
of production
being
reduced in the event that regulatory approvals are
not obtained or not obtained timeously.
19.3.3
Social Unrest
The
growing
frustration
of
society
due
to
lack
of
Government
service
delivery
and
high
rates
of
unemployment (heightened by
the impact of the Covid-19 pandemic)
lead to increased protests and
conflict,
affecting
communities
in
and
around
Ergo’s
operations.
This
may
result
in
operational
disruptions.
19.3.4
Increased Crime
The current
strained economic
and uncertain
socio-political environment
contribute to
adverse crime
trends.
Ergo operations
are
not immune
to crime
and
are
frequently
targeted by
criminals
as well
as
syndicates seeking access to gold or gold concentrate.
Technical Report Summary of the material Tailings
Storage Facilities
210
19.3.5
Depletion of Ergo
’
s Mineral Reserves
Ergo’s
strategy
is
to
maintain
its
Mineral
Reserve
base
by
improving
the
robustness
of
LoM
plan
by
increasing production through better extraction efficiencies. Another risk associated with Ergo’s Mineral
Reserve
is
the
depletion
of
higher-grade
Mineral
Reserves.
The
current
gold
price
assists
with
the
economic
viability
of
lower
grade
TSFs,
however
when
the
gold
price
drops,
it
will
be
important
to
optimize the
LoM plan
to enable
the mining
of lower
grade TSFs.
This will
require optimizing
the mining
throughput,
reducing
operating
costs
and
improving
the
mineral
recovery
efficiencies.
The
QP
associates a low to medium risk to the Mineral Reserve
base as some TSF are operating close to the cut-
off grade. In
certain instances, the risk
may be negated by
increasing the mining rate
of the TSF,
thereby
reducing the per unit operating cost and the cut-off grade.
19.3.6
Social Licenses to Operate
Historically, mining has taken place in the Johannesburg
area since 1886 and therefore, environmental
and waste disposal practices that were designed and that may have been adequate
in a less densely
populated environment, are inadequate today. Ergo’s entire operating footprint is the legacy footprint
of mining
in Johannesburg
specifically in
the East
Rand. An
integral part
of Ergo’s
mining process
is to
remedy the shortcomings of that legacy by mining
and the historical TSFs.
While mining, there can be
high levels of dust and
other disturbances from reclamation
sites, however,
the
result
is
a
better
and
cleaner
environment
once
the
TSF
us
removed.
To
minimize
the
impact
of
mining operations, Ergo conducts dust monitoring and
implements measures to suppress dust.
In addition, Ergo has adopted the strategy of concurrent
rehabilitation, which reduces Ergo’s long-term
environmental obligation. Ergo’s current mine design strategy is to
conduct rehabilitation of completed
mining
sites
as
soon
as
practically
possible
(See
Item
17
for
further
Environmental,
Social
and
Governance commentary).
Pressures
and
demands
on
business
by
local
communities,
non-government
organizations
have
increased. Social license to operate issues
are typically driven by the
social and economic landscape;
and
the
Covid-19
pandemic
has
exacerbated
the
social
and
economic
issues
in
South
Africa.
Unemployment, hunger and desperation are of great concern and Ergo has been active in supporting
the
local
communities.
Ergo
will,
however,
be
increasingly
exposed
to
this
risk
should
social
and
economic conditions in the country not improve.
19.3.7
Fluctuations in the Gold Price and Exchange Rate
As
a
market
price
taker,
Ergo
is
exposed
to
fluctuations
in
the
United
States
Dollar
gold
price
and
ZAR/USD exchange rate. The higher the gold price,
the higher the profitability. A noticeable upswing
in
the gold
price has
occurred since
March 2019
(Figure
19.4),
with a
peak
of USD1,970/oz
achieved
in
July 2020, and
a 30 June
2022 price
of USD1,829/oz.
Between the
August 2021 peak
and the July
2020
high,
a
gold
price
low
of
USD1,062
was
reached
in
November
2015,
indicating
price
volatility
of
approximately USD700/oz between the high and
low gold prices
from 2011 to 2022.
Technical Report Summary of the material Tailings
Storage Facilities
211
Figure 19.4:
30-Year Gold Price in USD/oz (1992 to 2022)
Source: Macrotrends.net, 2022
This is mainly because of investors returning to gold as a safe haven asset in the
wake of recent fears of
a
global
economic
slowdown.
The
ZAR/USD
exchange
rate
remained
volatile
throughout
the
year
mainly as
a result of
economic uncertainty
marred by
political instability
and global market
slowdown
sentiment.
Since the revenue
line is determined
by external factors,
Ergo manages
this risk by
being very focused
on areas that it can influence
such as costs and operational
efficiency. Ergo continues to
look at ways
to
impede
the
increase
of
costs
and
save
costs
by
making
ongoing
continuous
improvements
on
process and efficiencies. Precise dosing of
chemicals and consumables, based on the ongoing
analysis
of key drivers in the Ergo processing plant, contributes to keeping costs as low as possible;
lower friction
in pipelines
through HDPE
lining reduces
power consumption,
and maintaining
a closed
water circuit
and use of recycled water reduces the costs of water
consumption are a few initiatives implemented.
To limit
the vulnerability
to a
drop in
the price
of gold
in ZAR
terms, Ergo
monitors costs
in line
with the
approach stated above. In addition to that, Ergo
also works hard to increase recoveries.
19.3.8
Supply and Cost of Water
Ergo’s surface retreatment operations are reliant
on water to transport the slimes from reclaimed
areas
to the processing plant and to the TSF.
It is
acknowledged
that water
is a
limited
natural resource,
crucial
for the
sustainability
of the
planet
and
South
Africa
is
a
water-scarce
country.
There
are
increasing
calls
from
interest
groups
for
intervention
to
avoid
future
deficits
in
water
supply.
Over
the
past
few
years,
Ergo
has
deliberately
focused
on
investing
in
infrastructure
and
strategies
to
reduce
the
reliance
on
potable
water
and
expand the use of other water sources. Ergo relies
on third party providers for any shortfall in water.
Technical Report Summary of the material Tailings
Storage Facilities
212
20
Adjacent Properties
There are no adjacent properties to report.
21
Other Relevant Data and Information
Ergo is committed to improving
governance and transparency
in the safety and management
of TSFs,
a commitment that so far has taken Ergo to implement
the following:
●
an internal
Tailings Performance
Management System
(TPMS) was
implemented for
dedicated
data
collection,
storage
and
processing
to
ensure
the
integrity
of
the
data
for
day-to-day
management and oversight purposes;
●
quarterly drone surveillance;
and
●
review
of
historical
Interferometric
Synthetic
Aperture
Radar
(InSAR)
imagery
for
mapping
ground deformation over large areas.
An eternal Tailings Review Panel review panel has been
in place since 2018.
The
QPs
and
Ergo
have
a
number
of
internal
controls
to
manage
risk
and
uncertainty
in
the
Mineral
Resource
and
Mineral
Reserve
estimation
process.
Monthly
meetings
are
held
with
the
Ergo
MRM
Manager and the
Ergo/DRDGOLD Finance team
to discuss any
concerns or areas
requiring further work.
In addition to
these meeting, the
QPs liaise with
the relevant
specialists on
an on-going
basis to check
on progress of a number of technical programs.
There is
no other
known available
relevant data
or information
material to
the discussed
properties in
this regard.
Technical Report Summary of the material Tailings
Storage Facilities
213
22
Interpretation and Conclusions
The
QP
concludes
that
the
protocols
for
drilling,
sampling
preparation
and
analysis,
verification,
and
security meet industry
standard practices
and are appropriate
for the purposes
of a Mineral
Resource
estimate. The initial assessments have
found that the Ergo
TSFs have reasonable prospects
for economic
extraction.
The
QP
is
satisfied
with
the
QA
developed
by
The
RVN
Group
and
the
QC
program
implemented,
as there was no significant bias in reporting data.
The QP
contends
that the
assumptions, parameters
and methodology
used for
the
Mineral Resource
estimate are appropriate for the style of mineralization
and deposit type.
The
tonnage
and
content
of
the
TSFs
are
as
expected
and
can
be
processed
in
the
current
Ergo
processing plant. TSFs and
sand dumps reported in
this document have sufficient
information to be used
in the Mineral Reserve estimates and demonstrate economic viability.
The identified risks that could affect the Mineral Resources
and Mineral Reserves are:
●
rising electricity prices and Eskom supply distribution;
●
depositional capacity;
●
social unrest;
●
increased crime;
●
depletion of Ergo’s Mineral Reserves;
●
dependency on key suppliers;
●
social licenses to operate;
●
fluctuation of the gold price and the exchange rate;
●
extreme weather;
and
●
supply and cost of water.
23
Recommendations
There is sufficient information to allow for decision-making in the future. Accordingly, no additional work
is recommended.
Technical Report Summary of the material Tailings
Storage Facilities
214
24
References
Alakangas,
Eija.
(2015).
Quality
guidelines
of
wood
fuels
in
Finland
VTT-M-04712-15.
10.13140/RG.2.1.3290.3127.
Ellis. L., 2021.
Ergo Closure
Cost Assessment
2021, Digby
Wells Environmental,
Project Number
ERG7002.
June 2021. Unpublished.
Engles, J., (n.d.). Tailings Info. Sourced July 2022 - https://www.tailings.info/technical/hydraulic.htm
Goldprice, 2022. Sourced July 2022 - https://goldprice.org/gold
-price-today/2022-06-30
Macrotrends. (2022). Sourced July
2022 - (https://www.macrotrends.net/1333/historical-gold-prices-100-
year-chart)
Mudau, M.,
2017. Procedure
for
drilling
management,
logging,
sampling
and
analysis
of the
material
from Tailings Storage Facility. The RVN Group. Johannesburg.
The RVN Group. Unpublished.
Mudau,
M.,
2020.
Technical
Report
of
the
Daggafontein
Tailings
Storage
Facility.
The
RVN
Group.
Johannesburg. The RVN Group. Unpublished.
Mudau, M. and Rupprecht,
S.M., 2020a. Technical Report
of the Marievale Tailings
Storage Facility.
The
RVN Group. Johannesburg. The RVN Group. Unpublished.
Mudau, M. and
Rupprecht,
S.M., 2020b.
Technical Report
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Grootvlei Tailings
Storage Facility.
The
RVN Group. Johannesburg. The RVN Group. Unpublished.
Mudau, M. and
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2020c. Technical
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Rooikraal Tailings
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The
RVN Group. Johannesburg. The RVN Group. Unpublished.
25
Reliance on Information Provided by Registrant
The QPs relied on the following information provided
by the registrant:
●
legal matters about the Mining and Prospecting Rights. The QPs considered it reasonable to rely
on registrant’s legal
opinion (legal or
permitting matters are
discussed in Item
1.3, Item 3.3
to Item
3.6 and Item 17.2.6);
●
environmental matters discussed in Item 17.3 and Item
19.3.6 relating to Ergo compliance;
●
Ergo commits or plans to provide to local individuals or groups
(Item 17.3);
●
macroeconomic trends, data, and assumptions and interest
rates (Item 16); and
●
marketing information and plans (Item 16).
The QPs considered
it reasonable
to rely on
the above information
as the registrant
has the necessary
expertise and has been in operation for more than
20 years of successful and profitable retreatment
of
TSFs and sand dumps.
The QP also found that the data provided aligns with the industry norms. The QPs
have no reason to believe that any material facts
had been withheld or misstated.
Technical Report Summary of the material Tailings
Storage Facilities
215
Technical Report Summary of the material Tailings
Storage Facilities
216
26
Qualified Persons Disclosure Consent
We, the signees, in our capacity as Qualified Persons in connection with the Technical Report Summary
of Ergo Mining
Proprietary Limited dated 28 October 2022 (The Technical Report Summary) as required
by Item 601(b)(96)
of Regulation S-K
and filed
as an exhibit
to DRDGOLD Limited’s
(DRDGOLD) annual
report
on
Form
20-F
for
the
year
ended
30
June
2022
and
any
amendments
or
supplements
and/or
exhibits thereto (collectively,
the “Form 20-F”) pursuant
to Subpart 1300 of
Regulation S-K promulgated
by the U.S. Securities and Exchange Commission (1300
Regulation
S-K), each hereby consent to:
●
the
public
filing
and
use
by
DRDGOLD
of
the
Technical
Report
Summary
for
which
I
am
responsible as an exhibit to the Form 20-F;
●
the
use
and
reference
to
my
name,
including
my
status
as
an
expert
or
Qualified
Person
(as
defined by SK-1300) in connection
with the Form 20-F
and Technical Report Summary
for which
I am responsible;
●
use of any extracts from, or summary of, the
Technical Report Summary in the Form 20-F and the
use of
any information
derived, summarized,
quoted or
referenced from
the Technical
Report
Summary, or portions
thereof, that
is included
or incorporated
by reference
into the
Form 20-F;
and any amendments or supplements thereto.
I am responsible for authoring,
and this consent pertains to, the
Technical Report Summary (Table
26.1)
for which my name
appears below and certify
that I have read
the 20-F and that
it fairly and accurately
represents the information in the Technical Report
Summary for which I am responsible.
Table 26.1:
Qualified Person’s Details
Property Name
TRS Effective
Date
QP Name
Affiliation to
Registrant
Field or Area of
Responsibility
Signature
Ergo Mining
Proprietary Limited
(A subsidiary of
DRDGOLD Limited)
30 June 2022
Professor Steven
Rupprecht
Independent
Consultant
Item 1 and
12 to 19I
/s/ Steven
Rupprecht
Ergo Mining
Proprietary Limited
(A subsidiary of
DRDGOLD Limited)
30 June 2022
Mr Mpfariseni
Mudau
Independent
Consultant
Item 1 to 11 and
20 to 25
/s/ Mpfariseni
Mudau