Three-Layer Electrorefining of Molten Zinc Held on Porous Carbon or Silica Sheets in Molten LiCl–KCl–ZnCl₂

Abstract

We investigated a three-layer electrolysis process utilizing porous holding materials with poor wettability to molten metal, which enables to establish a three-layer configuration of metal(l)/electrolyte(l)/metal(l) by holding metals above the electrolyte regardless of their densities. In this study, porous carbon or silica sheets were used as the holding materials for electrorefining experiments of Zn metal in molten LiCl–KCl–ZnCl₂ at 723 K. Three types of experiments were carried out focusing on anodic polarization, electrorefining with cathodic carbon, and three-layer electrolysis using liquid Zn as cathode. The concentration of impurity elements in the Zn was reduced by a factor of 8 to 200 in this experimental condition, highlighting the purification effectiveness of the method. From the results obtained, we have identified certain challenges associated with the three-layer electrolysis process. Furthermore, we discuss potential prospects for industrialization.