Electrochemical Production of Bismuth in the KCl-PbCl₂ Melt

An anode dissolution of binary metallic lead-bismuth alloys with different concentrations of components has been studied in the KCl-PbCl₂ molten eutectic. The dissolution of lead is found to be a basic process for the alloys of Pb-Bi (59.3-40.7), Pb-Bi (32.5-67.5), Pb-Bi (7.0-93.0) compositions in the whole interval of studied anode current densities. A limiting diffusion current of lead dissolution was observed at 2 A/cm² and 0.1 A/cm² for the alloys of Pb-Bi (5.0-95.0) and Pb-Bi (3.0-97.0) compositions, respectively. The dissolution of bismuth takes place at the anode current densities exceeding the mentioned values. The number of electrons participating in the electrode reactions is detected for each mechanism. Based on the theoretical analysis, the experimental electrolysis of bismuth was performed in the laboratory-scale electrolytic cell with a porous ceramic diaphragm. The final product contained pure bismuth with a lead concentration of 3.5 wt.%.