XIANG Wang-li, LU Xian-cai, LU Yun-qiao, LI Juan, ZHANG Rui, CHEN Xiao-ye, LIU Huan
Nanjing University, School of Earth Sciences and Engineering, Key Lab of Surficial Geochemistry, Ministry of Education, Nanjing 210023, Jiangsu, China

Abstract: The acid mine drainage (AMD), produced by microbial weathering of sulfides in mine solid wastes, and the accompanying heavy metal contamination, are both serious environmental issues of concern. Calcite, a common mineral in rocks and ores, can affect the formation and migration of AMD. In order to investigate the influences of calcite on microbial oxidation of sulfides, this study carried out systematic simulation experiments and utilized multiple analytical techniques, including pH-Eh meter, SEM, ICP-AES, XRD, XRF to analyze the solution chemistry, mineral composition of secondary precipitates. The results showed that during the microbial oxidation process of the copper ore, pH declined while Eh increased, heavy metal ions were released and secondary precipitates were formed, including jarosite, sulfur, and so on. Adding excess calcite effectively neutralize the produced acid and significantly suppressed bacterial activities. These results suggested that the external regulations, such as increasing pH of the solution to alkaline, can remarkably affect the activity of microbe, thereby inhibit the oxidation of copper ore and favor the fix of heavy metals.

Keywords: copper sulfide ore Acidothiobacillus ferrooxidans microbial oxidation calcite heavy metals

*Corresponding Author, E-Mail: xcljun@nju.edu.cn

Bulletin of Mineralogy, Petrology and Geochemistry Vol. 33, No.6, 2014, page 764-771