Dissolution and Deposition of Impurities in Mg Electrolysis

Abstract

Electrochemical behaviors of Fe, Cr and Ni have been investigated in molten salt systems as a basic study on the electrorefining of Mg metal; The electrochemical behaviors of FeCl₂, NiCl₂ and CrCl₃ were examined by voltammetry, and the electrochemical dissolutions of these metals were also studied. A MgCl₂–CaCl₂–NaCl or MgCl₂–NaCl–KCl melt was used as electrolytic bath. The electrode reactions of these elements were discussed on these results, and it was concluded that these elements could be eliminated from Mg metal easily by electrorefining process in molten salts. Magnesium metal was obtained electrochemically not only above the melting point of Mg metal but also below the melting point. However, Mg electrodeposit with good morphology could not be obtained under any electrolytic condition below the melting point of Mg metal.