Bio-oxidation of arsenopyrite

Oxidation of arsenopyrite with Acidithiobacillus ferrooxidans was studied.The electrochemical results show that arsenopyrite is firstly oxidized to As2S2at the potential of 0.2-0.3 V(vs SHE)and As2S2covers the electrode and retards the process continuously.While at higher potential over 0.3 V(vs SHE),As2S2is oxidized to H3AsO3,and H3AsO3is then oxidized to H3AsO4at 0.8 V(vs SHE).The leaching results show that the addition of FeS2can promote the oxidation of As3+to As5+and increase the activity of the bacteria.The best bio-oxidation technical parameters are the initial pH of 1.8-2.0,particle sizes less than 0.074 mm, temperature in the range of 25-30℃and rotating speed of the orbital incubator of 100-160 r/rain.The results provide theoretical and technological supports of bio-oxidation arsenopyrite for pretreating refractory arsenic gold ores.