An Energy-Efficient and Environmentally Friendly Reductant in Magnesium Metal Production: Al_Dross

The vacuum metallothermic magnesiumMagnesium production process (the Pidgeon Process) is the leading method of magnesiumMagnesium production in the world. In this technique, theMg Mg content of calcined dolomite (CaO·MgO) is reduced with ferrosilicon (FeSi) to obtain an intermediate product called crown Mg. Due to thermodynamic constraints, the process is carried out in steel retorts under vacuum (1–10 mbar) at temperatures between 1200–1300 °C. Since FeSi production can be carried out with high electrical energy consumption and high CO₂ footprint, it is a techno-economicTechno-economics necessity to work on reductants that can operate at lower reduction temperatures, providing both low process GWP (global warming potential) and low process CO₂ emissions. In this study, the effects of a product containing 53.50% metallic Al obtained from Al drossAl Dross as a substitute reducing material instead of FeSi in Mg production were investigated. In experimental studies, the mixtures determined after stoichiometric calculations and thermochemical simulations were processed in a vacuum atmosphere (1 mbar) at 1200 and 1300 °C with processing times of up to 360 min. In the experiment, conducted for 6 h at 1300 °C, where 150% of the stoichiometric aluminum addition amount was used, theMg Mg content in the process slag decreased to 5.31% by weight and the reduction recovery rate was calculated as 80.81%. As a result of the reduction lasting 240 min with the addition of 5% CaF₂ to the charge under similar conditions, the amount of Mg remaining in the slag decreased to 2.61% and the highest recovery value achieved in this study is 90.87%.