Production of high-purity Mg metal from dolomite through novel molten salt electrolysis and vacuum distillation

In this study, a novel Mg production process for producing high-purity Mg metal from dolomite was developed. When the electrolysis of calcined dolomite was conducted using Cu cathode and C anode in MgF 2 - LiF molten salt at 1083-1173 K by applying an average current of 1.42-1.46 A for 9.50-21.0 h, the current efficiency of 66.4-88.6% was obtained. The produced Mg alloys consisted of MgCu 2 and Cu (Mg) or MgCu 2 and CuMg 2 phases, depending on the Mg concentration in the Mg alloy. When the electrolysis of calcined dolomite was conducted in MgF 2 - LiF - CaF 2 molten salt at 1083 K, the current efficiency was 40.9-71.4%, owing to undesired reactions such as electroreduction of Ca 2 + or/and CO 3 2 - ions. Meanwhile, the current efficiency increased from 40.9% to 63.2% by utilizing a Pt anode, because the occurrence of CO 3 2 - ions in the molten salt was prevented. After vacuum distillation of the obtained Mg alloys at 1300 K for 10 h, Mg metal with a purity of 99.9996-99.9998% was produced. Therefore, the feasibility of this novel process for the production of high-purity Mg metal from dolomite was demonstrated. & COPY; 2022 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing University

Automated summary

This study developed a novel Mg production process to obtain high-purity Mg metal from dolomite. Electrolysis of calcined dolomite using a Cu cathode and C anode in MgF2-LiF molten salt at temperatures of 1083-1173 K resulted in a current efficiency of 66.4-88.6%. The produced Mg alloys consisted of MgCu2 and Cu (Mg) or MgCu2 and CuMg2 phases, depending on the Mg concentration in the alloy.