Use of various MgO resources for high-purity Mg metal production through molten salt electrolysis and vacuum distillation

A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing MgO as a feedstock. The electrolysis of various MgO resources was conducted using a Cu cathode in MgF2 - LiF - KCl molten salt at 1043 K by applying an average current of 1.44 A for 12.5 h. The electrolysis of calcined North Korean magnesite and seawater MgO clinker yielded Mg alloys of MgCu2 and (Cu) phases with current efficiencies of 89.6-92.4%. The electrolysis of oxidized MgO-C refractory brick, aged ferronickel slag, and ferronickel slag yielded Mg alloys of MgCu2 and (Cu) phases with current efficiencies of 59.3-92.3%. The vacuum distillation of Mg alloys obtained was conducted at 1300 K for 10 h to produce high-purity Mg metal. After vacuum distillation, Mg metal with a purity of above 99.994% was obtained. Therefore, this study demonstrates the feasibility of the production of high-purity Mg metal from various MgO resources using a novel electrolytic process with a Cu cathode, followed by vacuum distillation. (c) 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