In the present work, the effects of amount of coke, reduction temperature, flux addition, and furnace types on copper slag smelting in a DC are furnace were studied. The optimum coke amount was found to be 10% of the slag weight in an open-top furnace for a 1 h reduction time in the temperature between 1703 and 1753 K. Similar conditions in a closed-top furnace resulted in higher cobalt and copper contents of the metallic matte, recoveries and reduction rates, as compared with the open-top furnace. In the covered system, for cobalt and copper, recoveries reach 95.7% and 90%, concentrations were 2.38% and 3.51%, respectively, and reduction rate constants were found to be 1.7 x 10(-3) s(-1). For both furnaces, higher reduction temperatures yielded higher reduction rates, but lower cobalt, copper and sulfur content in the metallic matte. By using the open-top design, it has been observed that fluxing materials CaO and Al2O3 had no appreciable influence on cobalt and copper recoveries.