Extraction of manganese from electrolytic manganese residue by bioleaching

Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn²⁺, while both the Fe²⁺ catalyzed reduction of Mn⁴⁺ and weak acidic dissolution of Mn²⁺ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn²⁺ and Fe²⁺ catalyzed reduction of Mn⁴⁺ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues.