Process of producing magnesium by thermal vacuum reduction using silicocalcium as reductant

A new process of producing magnesium by thermal vacuum reduction using dolomite and magnesite as materials and silicocalcium as reductant was studied in this study. The reduction process of MgO by silicocalcium was analyzed by phases analysis of reduction slag through X-ray diffraction (XRD) and the factors influencing the reduction ratio of MgO were investigated. The experimental results show that when using silicocalcium as reductant, the reduction ratio of MgO can be over 93 %. In the reduction process, calcium in silicocalcium takes part in the reduction reaction of MgO firstly below 1,000 °C and it makes CaSi₂ decompose. It also releases elemental silicon which has more reactive activity and improves the reduction reaction of MgO. That is the main cause that the reduction ratio of MgO using silicocalcium as reductant is 8 %–10 % higher than that by Pidgeon process using ferrosilicon as reductant under the same conditions.