Effect of Anions on Selective Solubilization of Zinc and Copper in Bacterial Leaching of Sulfide Ores

Effect of Anions on Selective Solubilization of Zinc and Copper in Bacterial Leaching of Sulfide Ores

Effect of Anions on Selective Solubilization of Zinc and Copper in Bacterial Leaching of Sulfide Ores

Abstract

Bacterial leaching of sulfide ores using Thiobacillus ferrooxidans, Thiobacillus thiooxidans, or a combination of the two was studied at various concentrations of specific anions. Selective zinc and copper solubilization was obtained by inhibiting iron oxidation without affecting sulfur/sulfideoxidation. Phosphate reduced iron solubilization from a pyrite (FeS(2))-sphalerite (ZnS) mixture without significantly affecting zinc solubilization.Copper leaching from a chalcopyrite (CuFeS(2))-sphalerite mixture was stimulated by phosphate, whereas chloride accelerated zinc extraction. In a complex sulfide ore containing pyrite, chalcopyrite, and sphalerite, both phosphate and chloride reduced iron solubilization and increased copperextraction, whereas only chloride stimulated zinc extraction. Maximum leaching obtained was 100% zinc and 50% copper. Time-course studies ofcopper and zinc solubilization suggest the possibility of selective metal recovery following treatment with specific anions.

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