Other liabilities (Tables)

12 Months Ended

Dec. 31, 2018


	2018			2017
	Non-			Non-
	Current	Current	Total	Current	Current	Total
	US$'000	US$'000	US$'000	US$'000	US$'000	US$'000
Payable to non-current asset suppliers	99	11,648	11,747	—	5,411	5,411
Guarantees and deposits	16	—	16	32	2	34
Remuneration payable	55	45,705	45,760	—	46,667	46,667
Tax payables	—	20,799	20,799	1,574	17,785	19,359
Contingent consideration	23,119	3,103	26,222	—	—	—
Other liabilities	1,741	22,315	24,056	1,930	20,704	22,634
Total	25,030	103,570	128,600	3,536	90,569	94,105


	2018			2017
	Non-			Non-
	Current	Current	Total	Current	Current	Total
	US$'000	US$'000	US$'000	US$'000	US$'000	US$'000
VAT	—	6,491	6,491	—	1,784	1,784
Accrued social security taxes payable	—	5,001	5,001	—	5,095	5,095
Personal income tax withholding payable	—	1,436	1,436	—	1,049	1,049
Other	—	7,871	7,871	1,574	9,857	11,431
Total	—	20,799	20,799	1,574	17,785	19,359

Vesting Conditions

30% total shareholder return (“TSR”) relative to a comparator group

30% TSR relative to S&P Global 1200 Metals and Mining Index

20% return on invested capital (“ROIC”) relative to a comparator group

20% net operating profit after tax (“NOPAT”) relative to a comparator group


	Grant date
	March 21, 2018			June 20, 2017			June 01, 2017			November 24, 2016
Fair value at grant date	$	22.56		$	15.90		$	16.77		$	16.66
Grant date share price	$	15.19		$	10.50		$	10.96		$	11.81
Exercise price		Nil			Nil			Nil			Nil
Expected volatility		49.86	%		43.15	%		43.09	%		44.83	%
Option life		3.00 years			3.00 years			3.00 years			3.00 years
Dividend yield		—	%		—	%		—	%		—	%
Risk-free interest rate		2.48	%		1.52	%		1.44	%		1.39	%
Remaining performance period at grant date		2.78			2.53			2.58			2.1
Company TSR at grant date		2.1	%		(0.3)	%		4.0	%		40.0	%
Median comparator group TSR at grant date		(6.2)	%		(7.2)	%		(3.7)	%		56.4	%
Median index TSR at grant date		(8.4)	%		0.6	%		4.8	%		45.7	%


		Number of awards
Outstanding as of December 31, 2016		264,933
Granted during the period		492,432
Exercised during the period		—
Expired/forfeited during the period		—
Outstanding as of December 31, 2017		757,365
Granted during the period		485,860
Exercised during the period		—
Expired/forfeited during the period		(218,183)
Outstanding as of December 31, 2018		1,025,042

Exercisable as of December 31, 2018 and December 31, 2017		—


				Weighted-
				Average
		Weighted-		Remaining
		Average		Contractual	Aggregate
	Number of	Exercise		Term in	Intrinsic
	Options	Price		Years	Value
Outstanding as of December 31, 2016	629,378	$	14.59	1.75		580
Exercised during the period	(34,990)		6.77
Expired/forfeited during the period	(71,027)		14.54
Outstanding as of December 31, 2017	523,361	$	15.12	0.89	$	1,774
Exercised during the period	(59,980)		5.89
Expired/forfeited during the period	(167,990)		17.99
Cancelled in lieu of cash settlement	(191,761)		12.54
Outstanding as of December 31, 2018	103,630	$	19.40	0.44	$	—

Exercisable as of December 31, 2018	103,630	$	19.40	0.44	$	—