The federal Bureau of Mines has developed a leach-electrolysis method for recovering lead from galena (pbs). Flotation concentrate is leached with ferric chloride (fecl3) solution to obtain leach chloride (pbcl2) and elemental sulfur, pbs+2fecl3->pbcl2+2fecl2+s deg. Over 99 pct of the pbs in the concentrate is converted to pbcl2. The leach solution, composed of brine (nacl) and fecl3, dissolve the pbcl2 as it is formed, leaving a residue of elemental sulfur plus gangue. Very pure pbcl2 (>99.9 pct) is crystallized from the leach filtrate on cooling and is subsequently electrolyzed in a fused-salt bath to obtain molten lead metal (>99.9 pct pb). Spent leach solution (fecl2) is regenerated for further use by reaction with the chlorine obtained in the electrolysis of lead chloride, and other values, such as ag, cu, zn, and s deg, are recovered by additional treatments of the leach solution and leach residue. This paper discusses results and conditions of the leaching and electrolysis operations.
Proc. Joint MMIJ-AIME Mtg., Denver, Colorado, V. 2, October 1976, PP. 603-621