Carbothermal Solid State Reduction of Manganese Ores: 3. Phase Development

Abstract

The paper considers phase development in the process of solid state carbothermal reduction of Wessels (South Africa) and Groote Eylandt (Australia) manganese ores in inert gases and hydrogen. Reduction starts with reduction of higher manganese oxides to MnO and iron oxides to metallic iron. When the graphite content in the graphite/ore mixture was in excess relative to the stoichiometric ratio, the final reduction product was (Fe, Mn)₇C₃ carbide. In the process of reduction of Groote Eylandt ore, silica also was reduced. In the reduction of high silica-ore, manganese oxide was predominantly reduced from tephroite and rhodonite. Silicon in the alloy was present in the form of ferro-manganese-silicon carbide and silicide (Fe, Mn)₅Si₃.