Comparative Leaching of Chalcopyrite by Selected Acidophilic Bacteria and Archaea

A systematic study of the bioleaching of chalcopyrite (CuFeS2) was conducted using axenic cultures of 11 species of acidophilic Bacteria and Archaea to obtain a direct comparison of the microbial chalcopyrite leaching capabilities of the different cultures and to determine the factors that affect Cu release. The characteristics of chalcopyrite leaching by the moderate thermophile Sulfobacillus thermosulfidooxidans, the mesophile Acidithiobacillus ferrooxidans, and the thermophile Acidianus brierleyi were used to elucidate the leaching process. Moderately thermophilic cultures of Sulfobacillus acidophilus; Acidimicrobium ferrooxidans, and Acidithiobacillus caldus were used to study the effects of different metabolic capabilities and relate those to leaching efficiency. The greatest rate of Cu solubilization from chalcopyrite was achieved at high temperatures (up to 70degreesC) at redox potentials below +550 mV (Ag/AgCl). The enhanced Cu solubilization observed at high temperatures resulted from accelerated chemical reaction rates, rather than from the rates at which individual acidophiles generated the mineral leaching reactants such as Fe3+.