Copper and antimony extraction from tetrahedrite‐containing dolomite heterotrophic bacteria

Three hundred and thirty‐five strains of heterotrophic bacteria, isolated from various metal‐containing ores, were tested in submerged culture for their capacity to leach copper and antimony from tetrahedrite‐containing dolomitic ore (particle size <0.1 mm; Schwaz, Austria). Experiments showed that after 8 days of incubation, it was possible to differentiate between active and inactive strains. Maximum extraction values for copper (1.0%) and antimony (1.6%) were achieved with Pseudomonas spp. after 8 days. Final pH values were 6.8 in sterile controls and slightly alkaline (up to pH 8.3) in inoculated flasks. Starch and glutamine (C/N ratio of 50:1) proved to be the best carbon and nitrogen sources for growth. Variation of the C/N source resulted in only a very slight increase in the rates of extraction for copper and antimony. Not even 24 h preliminary incubation of a culture before the ore was added improved metal extraction.