Recovery of Lead from Zinc Plant Residue by Alkaline Leaching Process Followed by Cementation

Present work focuses on recovery of lead from a zinc plant residue (ZPR) in alkaline media. Firstly, Zn and Pb were selectively extracted in NaOH from ZPR containing 56.9% Pb, 0.34% Ag, 3.93% Zn, and 0.88% Cu. Lead was effectively leached in a two-step process. The leach-I solubilized 39.5% Pb and 58.5% Zn in 2.0 M NaOH at 25 ℃ and 10% pulp density in 30 min. Subsequent leaching in 3.0 M NaOH yielded overall extraction of >99% Pb and 67% Zn with stage efficiency of 59.5% Pb and 8.5% Zn. Above 99.9% Pb was recovered from the leach liquor in 30 min at 25 ℃ and Zn: Pb mole ratio = 1.2:1.0 by cementation using Zn powder. Interestingly silver in the final residue was enriched from 0.3% to 1.17% making it a promising resource of Ag.