Hydrometallurgical Process for Producing Lead and Elemental Sulfur from Galena Concentrates

摘要

The Bureau of Mines has developed an effective hydrometallurgical method to recover high-purity Pb metal and elemental S from galena concentrates. The low temperature process eliminates S gases and Pb emissions, in contrast to the current high-temperature smelting technology. The method consists of (1) oxidative leaching with H2O2, PbO2, and waste fluosilicic acid at 95 degree C to produce a solution of PbSiF6 and a residue containing elemental S, (2) electrowinning the PbSiF6 solution at 35 degree C to produce 99.99 pct Pb metal and H2SiF6, and (3) solvent extraction to recover S, leaving a residue containing Cu, Ag, and other metal values. Spent electrolyte was recycled repeatedly, with impurity buildup controlled by controlling the leach parameters.