Preparation of High-Purity Manganese Sulfate Using Electrolytic Manganese Anode Slime: Leaching Mechanism and Impurity Removal Rule

Electrolytic manganese anode slime (EMAS) is a kind of solid waste produced in the anode chamber during the electrolytic production of metallic manganese, which contains a lot of Mn and Pb resources. In this study, the leaching of EMAS was enhanced by hydrogen peroxide, and the obtained leachate was successfully prepared into a battery-grade manganese sulfate product after impurity removal and concentration. The leaching efficiencies of Mn, Ca, Mg, K, Na, and Se in EMAS were 98.53, 82.20, 94.48, 91.37, 84.19, and 97.22%, respectively, and the mass fraction of Pb in the leaching residue was as high as 52.02%. Under the reaction condition, the mass ratio of EMAS to H2O2 is 1.2:1, the mass ratio of EMAS to H2SO4 is 1:1, at a temperature of 35 °C the liquid–solid ratio is 2.5:1, and the leaching time is 3 h. The leaching mechanism showed that H2O2 exhibited strong reducing property under a strong acid system, which could enhance the leaching of Mn. K in the leaching solution was mainly removed by the granite phase, and As and Pb were further removed in the form of sulfide. The purity of the prepared manganese sulfate product is as high as 99.66%, which meets the requirements of electronic-grade manganese sulfate (HG/T 4823-2015). This study provides a new method for the large-scale utilization of EMAS.