Experimental Study of Magnesium (Mg) Production by an Integrated Calcination and Silicothermic Reduction Short Process

To promote the innovation of raw magnesium production technology, an integrated calcination and silicothermic reduction short process for magnesium production was experimentally studied on the laboratory scale in this article. The influences of the thermal decomposition temperature, silicothermic reduction temperature, pelletizing pressures and silicon ratio on the characteristics of producing the magnesium by the short process was studied. The crosslinking effect, including reactions between CO₂ decomposed from dolomite and metal elements in ferrosilicon, microstructure change at thermal decomposition and silicothermic reduction stages, was analyzed and discussed. In addition, comparison of the magnesium reduction rate and production efficiency between the new short process and the traditional Pidgeon process was made. The results indicated that the decomposition and reduction temperatures have a more significant influence on the magnesium reduction process than the pelletizing pressure and silicon ratio. A decomposition temperature < 1000 °C and reduction temperature > 1100 °C was proven to be favorable for improving the magnesium reduction rate and production efficiency of the new short process. It was also found that the integrated short process for magnesium production can reach the same total reduction rate and has lower efficiency compared to the traditional process. The decrease of magnesium production efficiency in the new short process was expected to result from reduction of the contact area and hindering of diffusion between CaO·MgO molecules and Si(Fe) atoms because of the microstructure change and ferrosilicon consumption by the reactions between CO₂ and metal elements in ferrosilicon. Preparing briquettes with additives of binder or ultrafine particles of raw materials was proposed and considered for further study to improve the production efficiency.