Comparative Study of Microbial Contact Effect on Complex Copper Sulfide Concentrate Containing Enargite, Covellite and Digenite

In this study, the contact effects between mesophile bacteria and minerals were observed to enhance the bioleaching kinetics, which demonstrated that the adsorption of bacteria to mineral surfaces could improve the dissolution of arsenic and copper. The microstructure results also demonstrated that after the contact bioleaching, residue surfaces were rougher and with more corrosion bars and pits. Compared to contact oxidation approach, ferric ions, acting as the only oxidants in the non-contact bioleaching process, play a more important role in the copper extraction and arsenic dissolution, which is consistent with the previous works about indirect leaching mechanism. Due to the presence of various mesophiles in the contact oxidation, their activities and corresponding preferences for energy sources influenced by temperature were observed, causing differences in the sulfides’ dissolution: ferrous ions were inclined to be oxidized biologically at 30 °C, whereas sulfide minerals, including enargite, were preferentially oxidized at 45 °C.