Selective arsenic-fixing roast of refractory gold concentrate

A novel pretreatment technique suitable for gold extraction from refractory ores was developed. The technique was based on selective arsenic fixing, using a fixing agent in the conventional two-stage roast. As in the existing fixing roast, more than 92 pct of the arsenic was retained in the calcine, using sulfate and lime as selective arsenic-fixing agents in fixing roast process. The arsenate retained in the leaching residue was found to be stable. The selective fixing of arsenic allowed about 80 pct of the sulfur to be recovered for sulfuric acid production. Compared to the existing fixing roast, the amount of fixing agent added was reduced, accompanied by a reduction in solid-waste generation. Integrated in a two-stage roast under the optimal operating conditions identified, the new process resulted in a gold recovery of 89 to 91 pct from a typical refractory gold ore containing a substantial amount of pyrite, arsenopyrite, antimony, and carbonaceous and organic carbons.