Selective precious metals leaching from a chalcopyrite concentrate using chloride/hypochlorite media

An alternative non-cyanide lixiviant, namely sodium hypochlorite, has been used for the selective extraction of gold and silver from a copper concentrate. Hypochlorite leaching of the as-received, as well as aqueous pressure-oxidized copper concentrate was carried out. Direct hypochlorite leaching yielded gold and silver recoveries of 42.7% and 45.0%, respectively. With aqueous pressure oxidation followed by hypochlorite leaching, it was possible to selectively recover 90.0% of gold and 92.5% of silver from the copper concentrate.