Recovery of metallic Bi from Pb[sbnd]Bi slag: An integrated process of chloride leaching and electrowinning

Abstract

In this research, an effective approach for recovering metallic Bi from PbBi slag using selective leaching followed by Bi electrowinning was demonstrated. First, a thermodynamics calculation was performed to analyze the differences of solubility between PbSO4 and Bi2O3 in chloride system. Then the experiments results indicated that bismuth was selectively dissolved with a high leaching efficiency and lead was remained in the residue, which was agreed well with thermodynamics analysis. The effects of leaching parameters, i.e. CaCl2 concentration, L/S ratio, temperature and reaction time, on leaching were comprehensively studied. Under the optimum conditions, the leaching efficiency of bismuth and lead were found to be 99.2% and 12.2%, respectively. The leaching liquor were further treated with electrowinning at temperature of 50 °C and cathode current density of 150A/m2 to obtain 99.5% high-purity metallic Bi with a current efficiency of 85.46%.