Indium Extraction from Reiche Zeche Sphalerite and Community Analysis of Acidic Mine Water

Abstract

During the process of industrialization, the world-wide demand for resources steadily increases. Significant amounts of crucial metals and metalloids remain in low grade mineral deposits, however using conventional metal extraction methods on these minerals is not environmentally feasible. To overcome these problems, biohydrometallurgy has become the focus of recent research. Biohydrometallurgy utilizes the activity of iron-oxidizing bacteria to catalyze the dissolution of sulfide minerals, in our case local sphalerite (ZnS), with the aim of winning zinc and indium. To achieve this enrichment cultures originating from waters of the Reiche Zeche mine in Freiberg, Germany, were used as inoculum for two acidic growth media. To explore the efficiency of the bioleaching process leaching tests have been performed in shaking-flasks under laboratory conditions. Ground ore from Reiche Zeche is mainly comprised of the sulfide minerals sphalerite, galena and pyrite. After the leaching process both the solution and the residue were analyzed either by ICP-MS or XRD.The results clearly show that it is possible to leach indium and zinc from natural sphalerite, but that leaching efficiency is hindered, and dissolved indium removed, by the formation of iron-hydroxy precipitates. Hence, optimal conditions for maximum indium recovery with minimal precipitation have to be determined by variation of physico-chemical parameters. Furthermore, the microbial diversity of Reiche Zeche mine waters were studied with cultivation dependent and independent methods.