Novel hydro-electrometallurgical technology for simultaneous production of manganese metal, electrolytic manganese dioxide, and manganese sulfate monohydrate

Abstract

The main stages of a novel hydro-electrometallurgical technology for simultaneous production of electrolytic manganese metal, electrolytic γ-MnO2, and manganese sulfate monohydrate (MnSO4∙H2O) were tested at a large laboratory scale. The unified flow sheet comprised large and small process loops. The large loop included: concentrated sulfuric acid leaching of ore obtained by high-temperature reduction of manganese oxide ore; hydrolytic and sulfide purification of MnSO4 solution; production of crystalline manganese sulfate monohydrate obtained by high-temperature autoclave treatment of purified concentrated MnSO4 solution; feeding of hot spent MnSO4 solution from the autoclave as anolyte to an AMI-7001S anion membrane-separated electrochemical reactor where γ-MnO2 was produced on titanium anodes. The small process loop included preparation and correction of the catholyte composition using MnSO4∙H2O crystallized in the autoclave, from which electrolytic manganese metal was deposited on titanium cathodes. A heat pump was used to maintain the necessary temperature difference between the anolyte and catholyte. The energy consumed by the heat pump was half that obtained using an electrical current heating device. Electrical power consumptions for the production of manganese metal, manganese dioxide, and manganese sulfate monohydrate were 9.67 Wh/g, 3.75 Wh/g, and 0.884 Wh/g, respectively.