Abstract:Effects of various reaction parameters such as atmospheric pressure, treating temperature, sintering time and bituminite content on the preparation of primary Al-Si alloy by carbothermal reduction of bauxite tailings were investigated by XRD，XRF，infrared absorption carbon-sulfur analysis unit and SEM coupled with EDS. Meanwhile, the mechanism of carbothermal reduction of Al₂O₃ and SiO₂ was discussed. It is found that pressure and temperature are major factors that influence the carbothermal reduction of bauxite tailings. The appropriate conditions for preparation of primary Al-Si alloy are as follows: atmospheric pressure of 0.1 MPa, heating temperature of 1 900 ℃,bituminite content of 95% (mass fraction) of theoretic bituminite content and sintering time of 1 h. Among four mechanisms of carbothermal reduction of Al₂O₃ and SiO₂, the theory of the formation and decomposition of carbides might be the best one to interpret the reaction process.

Key words: primary Al-Si alloy; bauxite tailings; carbothermal reduction process; reduction mechanism