Sulfide ores of cu and ni are mixed with the oxide, hydroxide, or carbonate of ca or mg in sufficient amount to form cas or mgs with all the s, and heated at 600 deg-1,000 deg c in CO, h2, or a co-h2 mixture to reduce all the cus or nis to metal, which can be separated magnetically from sulfide or oxide residue. Although the direct reduction of cu2s by h2 is theoretically impossible, the reaction cao + cu2s + h2 -> cas + 2cu + h2o will proceed from left to right if h2 is supplied fast enough to carry h2o away. Sulfur was removed to 0.21 Wt pct in 3 h at 750 deg c by h2 flowing at 500 cm3/min from a mixture of equal weights of pentlandite and ca(oh)2. In the h2 treatment at 900 deg c of flotation concentrate containing fe 17, s 7.2, and cu 4.2 pct, which normally gave a product containing fe 34.8, S 10.4, and cu 8.4 pct, the results were fe 44, s <0.5, and cu 17.6 pct when cao was premixed with the ore according to this process.
U.S. Pat. 3,932,170; Jan. 13, 1976; Chem. Abstr. 84:153,619T