15 February 2012
South African gold miner DRDGold is to spend R250-million to expand its treatment plant in Brakpan, east of Johannesburg, a move that will enable the company to extract up to 20% more gold from the mine dumps that it re-treats.
According to DRDGold CEO Niel Pretorius, the decision to proceed with the addition of a flotation and fine-grind circuit to the plant stems from the findings of about two years of in-house research and development (R&D), the purpose of which was to find a way to liberate more gold from the mine dumps.
“It was discovered during R&D that gold trapped in high-pyrite material contained in the total feed to the Brakpan plant was not being liberated by the plant’s conventional carbon in leach process,” he told SouthAfrica.info this week.
The Brakpan plant forms part of the company’s Ergo operation, which was established in 2007 as a joint venture between DRDGold and Mintails Limited to recover and treat surface tailings in the Elsburg Tailings Complex.
Now wholly owned by DRDGold, Ergo has a network of surface rights that provide access to surface tailings deposited across the western, central and eastern Witwatersrand.
More gold extracted, possible uranium recovery
The company’s research also revealed that by putting the total feed to the plant through a flotation process, the high-pyrite material could be separated from the rest of the feed.
The separated high-pyrite material would then be fine-ground through a separate milling process, and the gold it contained could be recovered.
“So, the decision has been made to spend some R250-million to refurbish Ergo’s existing flotation plant to do the necessary flotation and to build a fine-grind milling circuit to fine-grind the high-pyrite material,” said Pretorius. “It is expected that the flotation [and] fine-grind process will liberate between 16-20% more gold.”
He added that the fine-grind process has another potential benefit: by linking it to resin-in-pulp technology, it should be possible to recover uranium contained in the feed material at a fraction of the cost of building and operating a conventional uranium extraction plant.
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