Electrochemical Separation of Pb-Ag-Sb Alloys in the KCl-PbCl₂ Melt

Abstract

Anode dissolution of lead, silver, antimony, and liquid lead-bismuth-antimony alloys has been studied by the polarization method depending on the alloy composition in the molten KCl-PbCl2 eutectic. Lead was found to dissolve and to form Pb2+ ions within the whole range of anode current densities in the Pb-Ag-Sb (49.0-28.0-23.0) and Pb-Ag-Sb (11.0-55.0-34.0) melts. The limiting diffusion current of lead dissolution was observed at the anode current density of 0.34 А/cm2 in the Pb-Ag-Sb (5.0-65.0-30.0) alloy. At the anode current densities exceeding these values the antimony dissolution was observed. To define a mechanism of metals electro dissolution, the number of electrons participating in the electrode reactions was calculated. Based on the polarization curves analysis the regime of electrochemical separation of lead alloys was selected. Metallic lead and the remaining Ag-Sb-Pb alloy with the valuable components concentration exceeding 90 wt.% were obtained in the laboratory-scale electrolytic cell.