PRETREATMENT OF ANTIMONIAL REFRACTORY GOLD AND SILVER ORES FOR IMPROVED CYANIDATION

In this study, the effect of roasting and alkaline sulphide leaching pre-treatments on gold and silver recoveries by cyanidation from an antimonial refractory ore was investigated. Alkaline sulphide leach test for decomposition of antimonial sulphides were performed using Na2S and NaOH solution as leachant. Up to 85% of antimony was removed by suitably adjusting the molar concentration of the leachant solution over two hours of leach time. Gold recovery in cyanidation was low (<= 50%) without pretreatment, but it was increased to 80% after alkaline sulphide pretreatment. Similarly, Ag recovery was significantly improved from 5-10% to 90% after Na2S pretreatment. This study has shown the feasibility of the alkaline sulphide leaching as pretreatment prior to the conventional cyanidation for antimonial refractory ores.