Recovery of metallic Bi from Pb-Bi slag: An integrated process of chloride leaching and electrowinning

In this research, an effective approach for recovering metallic Bi from PbeBi 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 degrees C and cathode current density of 150A/m(2) to obtain 99.5% high-purity metallic Bi with a current efficiency of 85.46%.