Abstract:Sulfides in the high-sulfur bauxite lead to serious steel equipment corrosion and alumina product degradation via the Bayer process, owing to the reactions of sulfur and iron-containing phases in the sodium aluminate solution. The effects of iron-containing phases on the transformation of sulfur-bearing ions (S^2-, , and ) in sodium aluminate solution were investigated. Fe, Fe₂O₃ and Fe₃O₄ barely react with and , but all of them, particularly Fe, can promote the conversion of to and S^2- in sodium aluminate solution. Fe can convert to in solution at elevated temperatures, and further react with S^2- to form FeS₂, but Fe₂O₃ and Fe₃O₄ have little influence on the reaction behavior of S^2- in sodium aluminate solution. Increasing temperature, duration, dosage of Fe, mole ratio of Na₂O_k to Al₂O₃ and caustic soda concentration are beneficial to the transformation of to and S^2-. The results may contribute to the development of technologies for alleviating the equipment corrosion and reducing caustic consumption during the high-sulfur bauxite treatment by the Bayer process.

Key words: high-sulfur bauxite; sodium aluminate solution; sulfur-bearing ion; iron-containing phase; transformation