Bioleaching of refractory gold ore (II)--Mechanism on bioleaching of arsenopyrite by Thiobacillus ferrooxidans

The variation of main parameters was examined in bioleaching arsenopyrite, such as arsenic concentration, solution pH value, potential and biomass. Solution pH value decreased slightly and few T ferrooxidans adhered to the surface of arsenopyrite. The surface properties of arsenopyrite and leached products were determined by using modern measurement techniques including SEM, EDS and XRD. The corrosion characteristic of arsenopyrite surface is of uniformity, and arsenic in arsenopyrite was preferential to be dissolved. Element sulfur, jarosite and scorodite are the primary products in bioleaching arsenopyrite. It can be drown from above that arsenopyrite is oxidized mainly through the indirect role of T ferrooxidans. A band model for bioleaching arsenopyrite was built, by which illustrated the bioleaching process theoretically. The model shows that the holes, which are provided by ferric ion, inject into the valence band of arsenopyrite to result in the dissolution of arsenopyrite.