Study of oxidation by bacteria of a difficult-to-dress gold-containing pyrite-arsenopyrite concentrate under moderately thermophilic conditions

摘要

The process of continuous oxidation of a gravitational gold-containing pyrite-arsenopyrite concentrate by bacteria has been studied. The bacteria used were a monoculture of Sulfobacillus thermosulfidooxidans and a community of S. thermosulfidooxidans and Thiobacillus ferrooxidans. Under moderately thermophilic conditions (42-52 deg C), the oxidation process attained stability when the pulp density corresponded to 8 wt % solid matter. In order to carry out the process in dense pulp (20 wt %), incubation conditions were varied. The concentrate was first oxidized at 30 deg C by the community of the mesophilic bacteria and S. thermosulfidooxidans; thereafter, the oxidation was effected at 42 deg C by the monoculture of S. thermosulfidooxidans. This approach made it possible to increase the oxidation rates of arsenopyrite and pyrite 2.4 and 4.5 times, respectively, as compared to those attained using the conventional procedure.