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

Abstract

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 24h for 97% of Mn release by the mixed culture under optimum conditions of 12g/L pyrite concentration, 100g/L pyrolusite content, 40°C of temperature and 180rpm of shaking speed. 96% of Mn dissolution was still obtained in a 30L reactor within 24h. 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.