Sulfide ores are treated, after grinding to <80 mesh and concentration by gravity or flotation, with cl2 gas at approximately 100 deg-115 deg c for approximately 30 min with sufficient o2 to react with the s and oxidize pb, fe, sb, and as to insoluble compounds. The amount of cl2 used should be restricted to that required for chlorination of nonferrous metals. From impure zns concentrates at least 90 pct of the zn, pb, ag, cd, and cu were extracted without fe by treating with 0.54 Lb cl2 and 0.13 Lb o2/lb concentrate. When the cl2 weight was 0.7 Lb with 0.13 Lb o2, 97 pct of the fe also was extracted. From impure pb-ag concentrates, treatment as a aqueous slurry with 30.5 Wt pct cl2 followed by o2 at 40 psig pressure gave cu 86.8, Ag 90.6, and pb 95.2 pct extraction, compared with 96.2, 97.9, and 98.9 pct respectively, when the same concentrates were treated as a slurry containing 20 pct nacl.
U.S. Pat. 3,981,962; Sept. 21, 1976; Chem. Abstr. 84:P138,945c