The effect of different media-compositions on sphalerite bioleaching

摘要

Sphalerite (ZnS) is a sulfidic mineral containing various precious metals and metalloids, which can be dissolved by activities of acidophilic iron- or sulfur-oxidizing microorganisms and subjected to leaching via the polysulfide mechanism. In the study presented here, mixed species communities of different iron-oxidizing bacteria like Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, sulfur-oxidizing bacteria and heterotrophic organisms like Acidiphilium spp. were enriched from environmental sites with mining capacity and subsequently applied to bioleaching. For leaching sphalerite four different acidic cultivation media were tested. During leaching-process pH, redox potential and zinc-content were monitored. The behavior of leaching trace-elements, focused on indium, was also analyzed by monitoring indium-extraction. Additionally, the microbial composition of leaching-culture was analyzed after successful bioleaching operation. The results clearly show that the leaching process is not only affected by composition of the leaching-media, but also for example by an increase of the microbial diversity. Hence the composition of the leaching culture influenced bioleaching of sphalerite, too.