Copper and silver are recovered from complex sulfide ores or concentrates containing, in addition, metals such as lead, zinc, arsenic, antimony, and iron by leaching with a combination of ferrous chloride and oxygen. For example, complex sulfide concentrate containing cu 25.0, PB 1.5, Sb 0.36, Fe 16.0, Zn 1.3, As 0.54 pct, and ag 1,266.6 Oz/ton, was ground to -80 mesh. 4,000 G of concentrate was slurried with 6,000 ml h2o and 3,840 g fecl2.4H2o in a 10-l closed reactor. Oxygen was added over a 4 h period, maintaining the pressure at about 50 psig, and the temperature between 100 deg and 140 deg c. The slurry was filtered and the residue was washed, then cyanided for 24 h and filtered again. The filtrate was placed in an electrolytic cell and the silver recovered as metal. Copper was recovered from the first filtrate by cementation with iron powder. Zinc may be recovered from the resulting copper-free solution by solvent extraction and the remaining fecl2 solution returned to the process. Extractions were, in pct: cu 98.2, PB <0.1, Sb <0.1, Fe <0.1, Zn 99, as <0.1, and ag 99.8.
U.S. Pat. 4,053,305, Oct. 11, 1977; Chem. Abstr. Not Found