The Bureau of Mines has developed a technique to separate and recover the three major components, pb, zn, and cd, from lead smelter flue dust. This research was conducted as part of the Bureau's effort to reduce environmental conflicts and occupational hazards associated with mineral-processing operations and to recover valuable constituents in emissions and effluents. The laboratory process utilizes sulfation roasting of the flue dust followed by water leaching to extract over 95 pct of the cadmium and zinc. Ninety-nine percent of the cadmium was recovered from solution by cementing with zinc dust, and zinc was electrowon from the resulting solution after purification. Zinc electrolysis was carried out in a 1-liter cell at 35 deg c with a cathode-current density of 8 a/dm2 in a solution containing 65 g/l zn++ and 180 g/l h2so4. Current efficiencies of 80 pct were obtained. The leached residue consisted largely of pbso4, which was converted to pbco3 and leached with h2sif6 to produce pbsif6 electrolyte. Ninety-five percent of the lead contained in the residue was converted to electrolyte. Lead was electrowon from solutions containing 70 g/l pb++ and 90 g/l h2sif6 using a lead cathode, pbo2-coated titanium anodes at 28 deg c, and a current density of 1.6. A/dm2. Current efficiencies approaching 92 pct were obtained. Accessory minerals such as cobalt and nickel were separated into purification residues and liquor.