Electrorefining of heavy nonferrous metals in molten electrolytes

Results of studying how the composition of metal and salt phases depends on electrorefining conditions and duration are shown. It is demonstrated that the existing designs of electrolyzers with liquid electrodes fail to provide the uniform distribution of current density over electrode surfaces thus favoring the complicated distribution of molten electrolyte components throughout the electrolyzer volume. This makes it impossible to assess a priori the content of impurities in the refined metal and in the fused electrolyte. An empiric method is proposed for assessing the time of electrolysis up to the production of a metal of desired purity as well as the concept of an electrolyzer that rules out the nonuniform current density distribution. To minimize the transfer of impurity metals from anode to cathode, the use of a porous auxiliary electrode is proposed and the conditions for co-discharge of cations on it are determined.