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Effects of Impurities in Electrolytes on Electrowinning of Lead from Lead Chloride.

Fleck DC; Sandberg RG; Wong MM
MISSING :8 pages
The Bureau of Mines, in a cooperative research program with four lead companies, has investigated ferric chloride leaching of galena to prepare lead chloride for molten-salt electrowinning to produce lead metal. The hydrometallurgical-electrolytic process is an alternative to the sintering-smelting-refining process currently used to produce lead metal and avoids the environmental problems associated with a conventional smelter. During investigations on the electrowinning aspects of the work, it was noted that certain cations, moisture, and sulfate in the electrolyte affect lead metal purity, cell voltage, current efficiency, and viscosity of the electrolyte. Results of bench-scale tests are reported on the effects of cacl2, cucl2, fecl2, mgcl2, nacl, zncl2, pbso4, and moisture on electrolysis. As impurities increased in the electrolyte, current efficiency decreased. Cacl2, cucl2, and fecl2, decreased current efficiency by 12 to 47 pct. Zncl2 gave a small voltage increase, while cacl2 addition equivalent to 4.9 pct ca caused a 50-pct increase in voltage. The lead metal was contaminated in direct proportion to the cucl2 buildup in the electrolyte. Anode corrosion was observed with mgcl2 and mgcl2.6H20. Viscosity increased appreciably with the buildup of nacl, cacl2, and sulfate. Electrolyte foaming occurred with zncl2, mgcl2.6H2o, mgcl2, fecl2.2H2o, and fecl2. Moisture inhibited the coalescence of the lead metal.
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
Identifying No.
RI 8742
NIOSH Division
Source Name
Page last reviewed: November 12, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division