Crown

Crown is the world’s largest gold surface retreatment facility, reprocessing the large and numerous sand and slimes dumps along the reefs that stretch from east to west just to the south of Johannesburg’s central business district (CBD). Most of these dumps hold waste from the stamp milling era of ore processing when plants treated the sand and slimes separately, unlike current milling methods which reduce all ore to slimes before the extraction of gold.

The dumps are reclaimed and mixed with water. The slurry is then pumped to one of Crown’s three processing plants: Crown Mines, 3km to the south, City Deep, 6km to the south-east, and Knights, 20km to the east of Johannesburg’s CBD. Using relatively modern milling methods and carbon-in-pulp (CIP) technology, these plants have the capacity to treat 11.76Mt of sand and tailings a year, recovering much of the gold. The land that is uncovered through removing the tailings is reclaimed and developed mainly for light industrial activities.

Owing to the low head grades, this is a low-margin business that relies on high volumes to be treated. As old dams are depleted, others are brought on stream.

Crown’s current major project is Top Star, a tailings dam to the south of Johannesburg’s CBD. Production is continuing apace from this 126 000-ounce resource.

In 2009 gold production decreased by 8% to 80 377 ounces (2008: 87 354 ounces) because of a 20% decline in throughput to 6 577 000 tonnes (2008: 8 235 000 tonnes). This reduction in throughput was intentional: it forms part of the closure plan for the Crown Tailings Deposition Facility. The goal is to lower throughput to 400 000 tonnes per month (4 800 000 tonnes per year) and this may be decreased further if the condition of this facility deteriorates.

Growth projects

Crown has secured the contractual right from jointly owned Ergo Mining (Pty) Limited to deposit its entire tailings flow on to the Brakpan and Withok tailings facilities. This has the potential to extend its life of mine by several years.

Work is under way on an environmental impact assessment for a proposed R212 million pipeline to link the Crown plants to ErgoGold’s tailings deposition site at Brakpan.

Crown and ErgoGold layout plan

Key statistics

		12 months to 30 Jun 2009	12 months to 30 Jun 2008
Ore milled	t’000	6 577	8  235
Yield	g/t	0.38	0.33
Gold produced	oz	80 377	87 354
	kg	2 500	2 717
Cash operating costs	US$ per oz	578	553
	ZAR per kg	168 034	129 908
	ZAR per tonne	64	43
Gold and silver revenue	(US$ million)	68.5	n/a
	(ZAR million)	620.1	n/a
Cash operating profit	US$ million	22.1	24.0
	ZAR million	200.0	175.7
Capital expenditure (net)	US$ million	4.8	5.8
	ZAR million	43.1	42.1