Science  05 Oct 2007:
Vol. 318, Issue 5847, pp. 27c
DOI: 10.1126/science.318.5847.27c

STRIKING SILVER. An international mining company has promised to pay $10 million for a clean and cost-effective way to extract silver from its Veladero mine in Argentina. The usual method uses a cyanide solution to leach out the precious metal. But the mine's estimated 180 million ounces of silver are encrusted with silica in particles a few micrometers in diameter, and the mineral has resisted every trick tried by scientists at the Barrick Gold Corp. in Toronto. The price of silver makes it too expensive to grind the ore down to the size necessary to make traditional leaching viable. “Our in-house metallurgists can't figure it out,” says Barrick spokesperson Vincent Borg. “The best way to solve [the problem] is to reach out” to the scientific community, he says.

Tibor Rozgonyi, a mining engineer at the Colorado School of Mines in Golden, says Barrick's offer is “a good approach” because it's likely to get many different heads thinking about a difficult problem. In addition to the prize, the company has announced that it will fund development and testing of promising techniques. “We are definitely considering [submitting] a proposal,” says Rozgonyi, who has been working with colleagues on using bacteria to extract ore.

Navigate This Article