Hydrometallurgical Extraction of Lead in Brine Solution from a TSL Processed Zinc Plant Residue

Brine leaching of a TSL processed zinc-plant residue (ZPR), containing 83.3% anglesite, has been investigated for lead recovery . A prior treatment of ZPR in acid solution did not show any significant effect of acid concentration in zinc dissolution. The study reveals that the solubility limits of PbCl₂ is as an important factor with respect to the brine concentration and pulp density in lixiviant. The dissociated sulfate ions hinder the formation of PbCl₂ on prolong leaching (above 60 min), while exhibiting the reverse solubility of lead as PbSO₄. A 3-step leaching process could yield >92% leaching efficiency when the parameters were maintained as: 10% pulp density in a 250 g/L NaCl solution, 80 °C temperature, and 60 min time. This leaves the insoluble ferrite, sulfides and oxy-sulfates of zinc and lead in the final residue as revealed by the XRD characterization.