Electrochemical characterization of the effects of impurities and organic additives in lead electrowinning from fluoborate electrolyte

The effects of glue and calcium lignin sulfonate additives, and chloride and antimony impurities on the lead electrowinning process, using a fluoborate electrolyte, were studied. Short-term deposition tests, voltammetry, electrochemical impedance spectroscopy (EIS) and SEM techniques were used for the evaluation. The interactions among additives and impurities were also evaluated. The presence of antimony or chloride ion in the range of 50 to 200 mg/L was shown to cause a more dendritic and powdery lead deposit. Additions of glue and calcium lignin sulfonate at selected concentrations helped to level the deposit and counteracted the detrimental effects of chloride and antimony. The voltammetry and EIS characteristics obtained with additions of glue and calcium lignin sulfonate to the electrolyte indicated the roles of these components in modifying the lead deposition mechanisms and the deposit morphology.