Abstract:Pure compounds and kaolin were employed to investigate the reaction behavior of ferric oxide in thetrinarysystem Fe₂O₃-SiO₂-Al₂O₃ during reductive sintering process. The thermodynamic analyses and reductive sintering experimental results show that ferrous oxide generated from the reduction of ferric oxide by carbon can react with silicon dioxide and aluminum oxide to form ferrous silicate and hercynite at 1173 K, respectively. In the trinary system Fe₂O₃-SiO₂-Al₂O₃, ferrous oxide obtained from ferric oxide reduction preferentially reacts with aluminum oxide to form hercynite, and the reaction of ferrous oxide with silicon dioxide occurs only when there is surplus ferrous oxide after the exhaustion of aluminum oxide. When sintering temperature rises to 1473 K, hercynite further reacts with silicon dioxide to form mullite and ferrous oxide. Results presented in this work may throw a new light upon the separation of alumina and silica present in Al/Fe-bearing materials with low mass ratio of alumina to silica in alumina production.

Key words: reductive sintering; ferric oxide; ferrous silicate; hercynite; mullite; kaolin