(See also chem. Abstr. 81:P66,961t) a new process operable at < / = 100 deg C in air to remove at least 1/2 of the sulfur as H2S, and most of the fe as a soluble ferrous salt, leaving cu as insoluble Cu2S or Cu, consists of reacting chalcopyrite with aqueous H2SO4 or HCl and powdered metal reductant, preferably Cu, Fe, or Pb. Sufficient acid, preferably 1.5-4N, must be used to provide a 3-9 times theoretical mole ratio of H+ to chalcopyrite, and the mole ratio of reductant to chalcopyrite should generally be 1.5-2 Times theoretical. Thus, 5 g of concentrate containing 80 pct CuFeS2 was mixed with 2.7 G copper dust finer than 200 mesh and treated 1 h with 200 ml 1.6M H2SO4 at 65 deg C without stirring. This gave 95.2 pct of the Fe converted to FeSO4, with about 50 pct extraction of S as H2S and most of the Cu in the insoluble residue as Cu2S. In another experiment, 5 g of the same concentrate was mixed with 4.8 G of 1/8-in electrolytic iron chips and 200 ml of 3.2N HCl solution at 65 deg C for 1 h, and 92.7 pct of the Fe was extracted with 90.8 pct of the S removed as H2S, and most of the Cu left as metal in the residue. Similar data are reported on the use of steel wool, and of pb finer than 65 mesh, as reducing agent instead of fe chips.
Us Pat 3,985,555; 10-12-76; Chem. Abstr. 85:P146,433v (Continuation in Part of Us Pat 342,920)