Study on reduction mechanism for silicothermic reduction of dolomite to produce Mg(v)

Abstract

The production of magnesium metal by direct reduction of MgO has been carried out on a commercial scale in the United Kingdom, U.S.A., Canada and Australia. Two basic methods have been exploited-reduction of MgO by carbon, and reduction by a metal or metalloid, the oxide of which is non-volatile at the temperature of the operation.The most useful reactive metals suitable for reduction of magnesium oxide are aluminum, silicon or their alloys. Recovery of magnesium by metallothermic technique can be improved by carrying out the reaction in the metallic oxides, whose silicates are more stable than magnesium orthosilicate during the reaction. Lime is a suitable addition to improve the reduction process of magnesium oxide. This study aims to study the silicothermic reduction mechanism from dolomite under vacuum. The discussion will take into consideration the type of intermediate compound formed during the reaction, and mechanism of the process. CaO/MgO molar ratios, addition of SiO2 are considered to have considerable effect on reduction of dolomite. The lab scale results are mainly discussed.