Reductive leaching of manganese from manganese dioxide ores by bacterial-catalyzed two-ores method

The two-ores method (TOM) has been well established for reductive leaching of MnO₂ under high reaction temperature and oxygen pressure. In this work, the TOM was carried out under ambient condition via biological catalysis. The results showed that the bacterial catalysis (BC) evidently improved the performance of TOM, especially the mixed culture consisting of Acidithiobacillus thiooxidans (A.t) and Leptospirillum ferriphilum (L.f) achieved an increase of 39% from 60% to 99% in Mn extraction. The leaching period was greatly shortened from 96 to 24 h for 97% of Mn release by the mixed culture under optimum conditions of 12 g/L pyrite concentration, 100 g/L pyrolusite content, 40 °C of temperature and 180 rpm of shaking speed. 96% of Mn dissolution was still obtained in a 30 L reactor within 24 h. The diffusion controlled model described well dissolution of MnO₂ ore by the BC-TOM. The bioleaching liquor was competent for preparing high purity electrolytic manganese metal.