An improved process of treating copper sulfide concentrates containing fe and other impurities consists in dead-roasting to remove >90 pct of the s as so2 for h2so4 manufacture and smelting the calcine in a cyclic 2-stage process in a single furnace. A mixture of calcine with sio2 or cao flux, and c in an amount approximately 160 pct of that required for reduction, is charged on the slag to reduce the copper oxide. The low-copper slag is then removed, and a second mixture of calcine with flux and sufficient c to reduce only approximately 40 pct of the oxide is melted and adjusted to produce acceptable blister copper tapped out under the slag. This smelting produced only a minor amount of so2 to the atmosphere. It also produced much less gas than conventional roasting, reverberatory furnace, and converter smelting, and less slag in which cu could be lost. The details of an operation on 1 ton conc/h containing cu 38 and fe 29 pct, in an 800 v-a arc furnace, are reported in which the slag/metal ratio was 0.7, The cu product contained <0.5 Fe, and cu in the slag tapped was 1.1-1.5 pct.