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 concentr ate. Hypochlorite leaching of the as-received, as well as aqueous pressure- oxidized copper concentrate was carried out. Direct hypochlorite leaching y ielded gold and silver recoveries of 42.7% and 45.0%, respectively. With aq ueous pressure oxidation followed by hypochlorite leaching, it was possible to selectively recover 90.0% of gold and 92.5% of silver from the copper c oncentrate. (C) 2000 Elsevier Science B.V. All rights reserved.