CHEN Bing-hui ^{1, 2}, WANG Meng-yuan^{1, 2}, WAN Mo-li¹, WANG Zhi-mei ³, LI Wen¹, CHEN Shu-jun¹

（1 Department of Earth Sciences, Sun Yat-sen University, Guangzhou 510275,China;
2 Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey, Guangzhou 510275, China;
3 Guangdong Pharmaceutical University, Guangzhou 510224, China)

Abstract: A strain of Acidithiobacillus ferrooxidans ( A.f.) isolated from the acid mine drainage (AMD) of Dabaoshan mine and a mineral galena were used to study the bio-oxidation of galena. Experiments were designed to compare the differences between abiotic oxidation and bio-oxidation of galena in pH2.00 and 3.00 with or without Fe2+ conditions. The concentrations of cations such as Pb2+, As5+ and Cd2+, anion SO42- and pH values during the experiments were measured, the solid experimental results were analyzed with XRD, and the changes of galena surfaces were investigated by a scanning electron microscope (SEM). The results showed that galena is easier to be oxidized in the condition of pH 2.00 than in pH 3.00.The iron ion promoted the bio-oxidation of the galena about 10 to 25times. The pH value of the final solutions of the bio-oxidation and of the existence of iron ion is much lower than that of abiotic oxidation. The results also indicated that the precipitation of lead sulphates in the bio-oxidation prevent the direct bio-oxidation of galena，so that bio-oxidation of galena may occur mainly in the “in-direct” form. Adding some alkaline substances in the acid mine drainage (AMD) can increase its pH value and reduce its iron ion concentration so that can decrease the bio-oxidation rate of galena and reduce the production of heavy metallic ions.

Key words: Acidithiobacillus ferrooxidans, galena, oxidation

EARTH AND ENVIRONMENT Vol. 39, No.4, Tot No.286, 2011, Page 503-510