Recovery of Silver, Gold, and Lead from a Complex Sulfide Ore Using Ferric Chloride, Thiourea, and Brine Leach Solutions

摘要

The Bureau of Mines investigated a hydrometallurgical procedure to recover gold, silver, and byproduct lead from a complex lead-zinc sulfide ore. A ferric chloride (FeCl3) preleach, at 40 C in 6 h, extracted about 50 pct of the zinc and formed insoluble silver and lead chlorides. Subsequent acid thiourea leaching, for 1 to 3 h at 40 C, extracted about 85 pct of the gold and silver. Lead chloride was solubilized from the remaining residue with NaCl brine solution at 55 C in 1 h. Lead metal was recovered from the brine solution in an electrolytic cell with an anion permselective membrane at a current efficiency of 95 pct and current density of 100 A/sq m. Spent FeCl3 leach solution was reoxidized in the anode compartment at a current efficiency between 75 and 95 pct.