Abstract:The process of aluminothermic reduction of a mixture of calcined dolomite and calcined magnesite had been developed. The mechanism of the process was studied by SEM and EDS. The reduction process was divided into three stages: 0≤η_t/η_f≤0.43±0.06, 0.43±0.06≤η_t/η_f≤0.9±0.02 and 0.9±0.02≤η_t/η_f <1, where η_t and η_f are the reduction ratio at time t and the final reduction ratio obtained in the experiment at temperature T, respectively. The first stage included the direct reaction between calcined dolomite or calcined magnesite and Al with 12CaO·7Al₂O₃ and MgO·Al₂O₃ as products. The reaction rate depended on the chemical reaction. The CA phase was mainly produced in the second stage and the overall reaction rate was determined by both the diffusion of Ca²⁺ with molten Al and the chemical reaction. The CA₂ phase was mainly produced in the third stage and the reaction process was controlled by the diffusion of Ca²⁺.

Key words: magnesium; aluminothermic reduction; magnesite; dolomite; mechanism