ISIJ International, Vol. 44 (2004), No. 9, pp. 1480–1487 Reduction of Manganese Oxides by Methane-containing Gas Nathaniel ANACLETO, Oleg OSTROVSKI1) and S. GANGULY2) Formerly PhD Student, School of Materials Science and Engineering, University of New South Wales, Sydney, now at MSU- IIT, Tibanga, Iligan City, 9200 Philippines. 1) School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 Australia. E-mail:
[email protected] 2) Tasmanian Electrometallurgical Company, Bell Bay, Tasmania 7253, Australia. E-mail:
[email protected] (Received on February 12, 2004; accepted in final form on June 8, 2004) The paper presents results of reduction of pure manganese oxides by methane containing gas in non- isothermal and isothermal experiments and reduction mechanisms. The extent and rate of manganese oxide reduction were determined by on-line off-gas analysis using a mass-spectrometer in a fixed bed labo- ratory reactor in the temperature range 1 000–1 200°C at different gas compositions. Manganese oxides were reduced to carbide Mn7C3. High extent and rate of reduction by methane-con- taining gas in comparison with carbothermal reduction were attributed to high carbon activity in the reduc- ing gas, which was in the range 15–50 (relative to graphite). The rate of reduction of manganese oxide in- creased with increasing temperature. Increasing methane content in the reducing gas to 10–20 vol% CH4 favoured the reduction process. Increase in hydrogen partial pressure had a positive effect on the reduction rate. Addition of carbon monoxide to the reducing gas retarded the reduction process. The addition of Fe3O4 to manganese oxide increased the rate of reduction.