Enhancement of copper dissolution from a sulfide ore by using Thiobacillusthiooxidans

Copper dissolution from a sulfide ore (with covellite as the main copper ph ase) was investigated in cultures of Thiobacillus ferrooxidans or Thiobacil lus thiooxidans and in abiotic controls. In unsupplemented media, T. ferroo xidans was more efficient than T. thiooxidans. In the presence of ferric ir on, the dissolution of covellite was not significantly different in culture s inoculated with T. ferrooxidans or T. thiooxidans. However; the most extr action was found in T. thiooxidans cultures supplemented with ferrous sulfa te. The first results were explained by the mechanism proposed by Schippers and Sand (Appl Envir Microbiol 65:319-321, 1999), which involves polysulfi des and sulfur as intermediates. This mechanism was extended to explain the behavior of T. thiooxidans culture supplemented with ferrous iron.