Preparation of Mg and Ca metal by carbothermic reduction method – A thermodynamics approach

The Gibbs free energy and critical reaction conditions of preparing Mg and Ca metal by carbothermic reducing calcined dolomite were calculated and analyzed. New thermodynamic criterion for reduction reaction, including the critical temperature and vacuum degree, was studied. The results show that: when T/P0.0449 < 1199.2, neither MgO nor CaO can be reduced by carbon; when T/P0.0449 ≥ 1199.2 and T/P0.0462 < 1350.9, MgO can be reduced while CaO can not be; when T/P0.0462 ≥ 1350.9, both MgO and CaO can be reduced. According to the requirements, we can obtain only Mg, Mg first then Ca, Mg and Ca simultaneously by controlling temperature, vacuum degree or both of them properly, by carbothermic reducing calcined dolomite.