FUNDAMENTAL-ASPECTS OF FUSED-SALT ELECTROREFINING OF ZINC

A study has been made of the physicochemical properties of possible electrolytes for the fused-salt electrorefining of zinc. The properties investigated included conductivity, density, diffusivity, surface tension and viscosity in melts that were composed of ZnCl2, KCl and NaCl plus, in some cases, LiCl at temperatures from 675 to 775K. The relative emf difference from zinc of Cd, Fe, Pb Cu and Ag in these electrolytes was determined by electrochemical studies, and it is shown that the relative order can be changed by altering the halide in the electrolyte. For zinc ions in a chloride melt values for the molar exchange current density, cathodic transfer coefficient and molar heterogeneous rate constant were determined by ac and dc perturbation techniques.