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

He Zhong-bing (贺仲兵)^1,2, Liao Ting (廖婷)^1,2, Liu Yun-guo (刘云国)^1,2, Xiao Yu (肖玉)^1,2, Li Ting-ting (李婷婷)^1,2, Wang Hui (王

(1. College of Environmental Science and Engineering, Hunan University,
Changsha 410082, China;
2. Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education),
Hunan University, Changsha 410082, China)

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.

Key words:bioleaching; mine tailings; sulfur addition; solid content; heavy metals