Influence of sulfur addition/solids content ratio on removal of heavy metals from mine tailings by bioleaching

Abstract

The effect of sulfur addition/solids content (SA/SC) ratio on heavy metals (e.g. copper, zinc and lead) obtained from mine tailings by indigenous sulfur-oxidizing bacteria was studied, and the changes in the chemical forms of heavy metals after bioleaching were explored. The results show that the solubilization of metals is significantly influenced by SA/SC ratio, and SA/SC ratio of 2.50 is found to be the best for bacterial activity and metal solubilization among six SA/SC ratios tested (such as 1.00, 1.33, 1.50, 1.67, 2.00 and 2.50) under the chosen experimental conditions. The pH decreases fast and the maximum solubilizations of copper and zinc are respectively 81.76% and 84.35% while that of lead only reaches 40.36%. After bioleaching, the chemical forms of heavy metals have changed. The metals remained in mine tailings are mainly found in residual fractions, which is harmless to the surrounding environment.

Keywords

bioleaching / mine tailings / sulfur addition / solid content / heavy metals

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