A vast footprint
Ergo Mining Proprietary Limited (Ergo) has a vast footprint adjacent to Johannesburg on the central and eastern Witwatersrand of South Africa. Its assets cover an area approximately 62km from east to west and 25km from north to south. This large, single footprint was created as part of a rationalisation process and in order to simplify the structure of DRDGOLD’s companies. A single retreatment business also has the effect of improving synergies and saving costs.
The company’s flagship metallurgical plant, Ergo, some 50km east of Johannesburg in Brakpan, and the Knights plant in Germiston, together comprise what is arguably the world’s largest gold surface tailings retreatment facility. Together with the milling and pump station at Crown Mines and City Deep (both former plants), the new consolidated Ergo operation processes 2.0Mt to 2.1Mt of gold-bearing material a month.
The Ergo footprint[Zoom in]
History: DRDGOLD acquires Ergo
Ergo1 was re-established in 2007 as Ergo Mining Proprietary Limited – a joint venture between DRDGOLD and Mintails Limited. The primary aim was to recover and treat – over a period of 12 years – some 186Mt of surface tailings contained in the Elsburg tailings complex and the L/29 dump. These tailings were estimated to contain some 1.7Moz of gold.
DRDGOLD acquired part of the Mintails stake in 2008, and the remainder in 2010.
Linking the assets
Ergo’s assets include access to some 750Mt to 900Mt tonnes of tailings deposited across the western, central and eastern Witwatersrand. Initially, four plants were involved in the retreatment of tailings. Rationalisation and restructuring has resulted in the decommissioning of the Crown and City Deep plants, and their conversion into milling and pump stations.
The Ergo plant – with a 25.2Mt annual capacity – is treating material from a variety of sources, the majority of which is fed to the plant via two feeder lines from the Elsburg tailings complex and the L/29 dump. Another 600 000tpm is pumped from Crown Mines and City Deep via a 50km pipeline which was constructed to link the assets as part of the rationalisation process. Recently, the refurbishment of five unused CIL tanks at Ergo has increased processing capacity by 300 000tpm to 2.1Mtpm.
¹ Anglo American Corporation commissioned the Ergo plant in Brakpan in 1977. The operation became part of AngloGold Ashanti in 1998 and was closed by that company in 2005.