Magnesium Production by Silicothermic Reduction of Dolime in Pre-prepared Dolomite Pellets

A novel process has been proposed for magnesium production, in which powder materials including dolomite, ferrosilicon, fluorite and binder are mixed to produce pellets. Kinetics of the silicothermic reduction using the pre-prepared dolomite pellets was investigated by a non-isothermal, flowing argon-protected gravimetric technique at a temperature range from 1323 K to 1673 K. The results suggest that the process is controlled by a chemical reaction, with the second-order chemical reaction model providing the best representation of the process. The apparent activation energy was determined to be 280 kJ/mol. Calcium silicide (was found in the pellet after calcinations. The silicothermic process in the pre-prepared dolomite pellets is possibly a solid–liquid reaction since calcium silicide transformed into liquid alloy, which reduced diffusion resistance of silicon during the reduction process. The gas–film mass transfer may have some effect on the reduction kinetics but is not the major rate-limiting step.