Chalcopyrite ore or concentrate is decomposed by reacting with an aqueous acid solution of a transition metal ion in a lower valence state, the metal being from the group consisting of chromium, vanadium, and titanium. Thus, 20 g of flotation chalcopyrite concentrate, containing cu 26.5, Fe 26.6, S 30.9, and insolubles 10.0 pct, were placed in a stoppered flask. The inlet to the flask was connected to the bottom of a tube containing mossy zinc and the outlet was connected to a gas washing bottle containing sodium hydroxide solution. Three hundred milliliters of a solution containing 130 ml concentrated hcl (37 pct) and 17 g of chromium trioxide (cro3) in distilled water was run through the zinc column. Cr6+ was reduced to light blue cr2+ ion and was run into the flask with the chalcopyrite concentrate, where it was mixed at room temperature and pressure for 10 min, then filtered, and the residue washed and dried. The residue weighed 10.63 G. The filtered solution was run through the zinc column again and mixed with the leached residue for 20 min, filtered, and the residue washed and dried. This residue weighed 10.00 G. The leach solution now contained the green chromic ion (cr3+) and 86 pct of the iron in the original concentrate. The residue analyzed cu 50.0, Fe 7.4, and s 17.6 pct. Seventy two percent of the sulfur in the original concentrate was evolved as h2s and was collected in the naoh solution.
U.S. Pat. 3,958,983, May 25, 1976; Chem. Abstr. Not Found