Effect of magnesium fluoride catalysis on the vacuum reducing properties of magnesium oxide

Abstract

Low reduction efficiency is a critical issue that limits the advancement of the magnesium vacuum carbothermal reduction smelting process. This investigation introduces a novel magnesium smelting process that substitutes magnesium fluoride (MgF₂) for calcium fluoride (CaF₂) as a catalyst in the vacuum carbothermal reduction of magnesium. The viability and optimal operating conditions of the new method were assessed through thermodynamic calculations of Gibbs free energy in the MgOC-MgF₂ system. Additionally, the catalytic effects of MgF₂ on the reduction of MgO were examined under different holding times in vacuum conditions. Analytical results indicated a significant improvement in the reduction efficiency of MgO upon the incorporation of MgF₂. MgF₂ serves a catalytic function in the reduction process, When F⁻ acts, it elevates the relative concentration of Mg in the reduction system and promotes the reduction reaction. Improvements in reduction efficiency are observed as the holding period duration increases and with higher concentrations of MgF₂. However, the improvement in reduction efficiency tends to plateau when the concentration exceeds 7 %. The resulting magnesium condensate exhibits a robust crystalline structure, with a purity of 79.39 %. The crystallization outcomes are influenced by the degree of reverse reactions. Compared to CaF₂, MgF₂ offers significant economic, environmental, and catalytic advantages. This process supports the goals of sustainable, green development and aligns with clean production standards in the magnesium metallurgy sector.