A Thermodynamic and Experimental Assessment of the Recovery of Copper, Iron, Zinc, and Lead from Copper Slag

With the increases in the costs of iron and copper ores, the incongruity between the significant imports of these ores into China and the ongoing accumulation of unused copper slag has greatly increased. Even so, there are few low-value methods for the utilization of copper slag. The present work demonstrates the processing of this material via reduction whilst smelting wear-resistant cast iron. This system is able to recover copper, iron, zinc, and lead. The FactSage software package was used to calculate the reduction thermodynamics of the copper slag, and suitable conditions for the processing of this slag were experimentally investigated. The thermodynamic calculations indicated that copper, zinc, and lead oxides could all be readily reduced whereas the reduction of sulfides was more difficult than that of oxides. The most suitable conditions for the reduction of copper slag comprised a temperature of 1450 °C, an alkalinity of 1.2, and a reducing agent ratio of 0.225. This newly developed process was found to recover 95.49% of copper and iron from the slag along with 83.54% of lead and 98.30% of zinc. The copper-containing molten iron obtained could be used to create wear-resistant cast iron.