Effects of iron, arsenic and carbon removal from a dust of refractory gold concentrates on cyanide leaching

A dust of refractory Au concentrates was used as raw material. The effects of sodium hydroxide leaching, sulfuric acid leaching and sulfuric acid-sodium hydroxide combined leaching on the As, Fe, and C removal and cyanide leaching were studied.The results show that As and C removal rate, at 6 mol/L NaOH concentration, are 99.66% and 60.63%, respectively. And Au leaching is 58.90% and increases by 4.60% compared to direct cyanide of the dust. The effective removal of arsenic can not effectively improve the gold leaching efficiency. Fe, As and C removal rate, at 15% sulfuric acid concentration, increases from 0 to 33.65%, 80.38% and 12.59%, respectively. And Au leaching effieciency increases to 80.40%. Compared with sodium hydroxide aching, Fe removal with sulfuric acid leaching can effectively improve the gold leaching efficiency. Through once cyanide leaching after 15% sulfuric acid leaching and twice 2 mol/L NaOH and cyanide leaching, the total removal rates of iron, arsenic and carbon in the dust are up to 33.65%, 95.63% and 79.60%, respectively, the total leaching efficiency of gold is 91.90%, and the content of gold in cyanide residue is 3.31 g/t with residue rate of 80.33%. Compared with the direct cyanide leaching, the gold leaching efficiency increases by 37.60%. © 2020, Science Press. All right reserved.