Selective recovery of manganese and lead from electrolytic manganese residues in a sulfuric acid solution with galena as the reductant

Abstract

Electrolytic manganese residues (EMRs) were considered as typical industrial solid wastes owing to a large amount of Mn and other elements such as soluble sulphate. Here, lead-chemistry was innovatively proposed to treat EMRs based on the transformation of lead phases including PbS, PbSO4 and PbCO3. During the first stage H2SO4 leaching with galena as the reductant, Mn leaching efficiency reached 98.0% in a 1.5 mol/L H2SO4 solution with m(galena)/m(EMR) = 0.1. Meanwhile, Pb was enriched in the H2SO4 leaching residue with a content of 53.0 wt%. Subsequently, >77.2% of Pb was recovered in the form of PbCO3 product through NH4Ac leaching and (NH4)2CO3 precipitation in a 4 mol/L NH4Ac solution. Finally, the NH4Ac leaching agent was successfully regenerated after removing remaining CO32− and SO42− via PbCO3 and BaSO4 precipitation. The regenerated leaching solution indicated a higher Pb recovery to 85.4% owing to an increasing NH4Ac concentration to 5 mol/L during circulation leaching. This study provided a feasible method for the effective recovery of Mn and Pb, which was beneficial for the clean utilization of EMRs.