Simultaneous sulfide oxidation and gold leaching of a refractory gold concentrate by chloride-hypochlorite solution

In this research, oxidation of sulfide and leaching of gold from a gold-bearing sulfide concentrate using chloride-hypochlorite solution has been investigated. Effects of calcium hypochlorite concentration, initial pH and sodium chloride concentration on the recovery of gold were examined. Two conditions were considered; the stability range of the gold complex (Eh > 900 mV) and formation of chlorine gas (pH < 3.5). During leaching, due to oxidation of sulfide and generation of acid, pH dropped. About 82% of gold was extracted from 200 g/L concentrate after 2 h using 200 g/L Ca(OCl)(2), 200 g/L NaCl at initial pH of 11, stirring speed of 600 rpm and temperature of 25 degrees C. (C) 2012 Elsevier Ltd. All rights reserved.