Solid state carbothermal reduction of alumina

Abstract

The Hall-Héroult process, the only commercial technology for aluminum production requires high energy and is a major origin of perfluorocarbons and green house gases. A promising alternative process, carbothermal reduction of alumina to metallic aluminum has advantages of lower capital cost, less energy consumption, and lower emission of green house gases. Carbothermal reduction processes under development are based on formation of aluminum carbide-alumina melts at high temperatures. Solid state carbothermal reduction of alumina is possible at reduced CO partial pressure. This paper presents results of experimental study of carbothermal reduction of alumina into aluminum carbide in Ar, He and H2 atmospheres at 1500-1700°C. The reduction rate of alumina increases with increasing temperature, and is significantly faster in He and H2 than in Ar. Increasing gas flow rate and decreasing pressure favors the reduction.