A novel low-energy route for the extraction of copper and cobalt metals/alloys from the Zambian sulphide concentrates

Conventional smelting of copper – cobalt – iron sulphide concentrates result in the oxidation of cobalt and iron, which are subsequently lost into the slag. The emission of SO2 bearing gas from smelting causes serious health and environmental problems. In this research, three different types of copper–cobalt–iron sulphide concentrates, derived from froth flotation, were investigated. In this investigation, the concentrates, each containing more than 40 wt % percent gangue material, were directly reduced in the presence of lime and carbon in the temperature range of 1073 K – 1573 K, for the production of an alloy containing copper, cobalt and iron. We demonstrate the basic principles of process physical chemistry for the recovery of alloy by carrying out a detailed process analysis utilising the predictions from thermodynamic equilibrium and the results from the kinetics of reduction reaction. The effect of temperature on the reduction kinetics and alloy formation were determined and analyzed in detail.