Selective leaching of lead from complex polymetallic sulfide secondary concentrate with ferric methanesulfonate and methanesulfonic acid solution

Abstract

The selective leaching of lead from complex polymetallic sulfide secondary concentrate (CPSSC) with the solution mixed by ferric methanesulfonate and methanesulfonic acid (Fe(MS)3-MSA) was investigated by leaching experiments, analysis of solids, and electrochemical characterizations. The leaching results showed that stirring rate, liquid–solid ratio, temperature, and ferric concentration greatly influenced Pb extraction rate. At the optimum leaching conditions, 93.1 % Pb, while 3.8 % Cu and 18.8 % Fe were extracted. The selective leaching mechanism was related to the activity of PbS in Fe(MS)3-MSA solution and the galvanic effect between sulfides. XRD and SEM-EDS results of leaching residues verified the selective decreases in PbS, and retainment of most Cu, Fe, and Zn. Electrochemical characterizations demonstrated a more stable and higher open-circuit potential, and an increase/decrease in A0 peak potential/current in LSV curve for the residue’s electrode, suggesting the selective decreases in active components (e.g. PbS). After selective leaching, Cu could be easily extracted from residues by pressurized water leaching, and Fe(MS)3-MSA solution could be regenerated for recycling used in leaching. These results indicate the great potential of Fe(MS)3-MSA solution to selectively leach and separate Pb from CPSSC, and unveil a method to effectively treat refractory CPSSC.