Carbothermal Solid State Reduction of Manganese Ores : 2. Non-isothermal and Isothermal Reduction in Different Gas Atmospheres

Non-isothermal and isothermal carbothermal reduction of Australian Groote Eylandt and South African Wessels manganese ores was studied in hydrogen, helium, argon and hydrogen–carbon monoxide atmospheres. Reduction experiments were conducted in a fixed bed reactor in a vertical tube furnace, with on-line monitoring of gas composition by CO–CO2 infrared sensor. The extent of reduction was calculated using the off-gas composition and oxygen content in the reduced samples measured by LECO. The reduced samples were analyzed by XRD and EPMA. Reduction of manganese ores was strongly affected by temperature and ore chemistry. In all gas atmospheres, the reaction rate increased with increasing temperature. The reduction rate of manganese ore in hydrogen was higher than in helium, and in helium higher than in argon. Rate and extent of reduction of Wessels ore were higher in comparison with Groote Eylandt ores.