Feasibility of Recovering Valuable and Toxic Metals from Copper Slag Using Iron-Containing Additives

One of the greatest environmental challenges in metal extraction is the generation of a large amount of slag. Most of these slags contain insufficient amounts of valuable metals for economical revalorization, but these concentrations may be harmful for the environment. At present, more than 80% of the global copper products are obtained by the smelting process, where the major by-products are various slags containing a broad range of almost all known elements. In this study, valuable and potentially harmful elements were recovered from mining waste using gravity separation and gravity settling. The settling process was enhanced by injecting coke, ferrocarbon, ferrosilicon, and ferrosulfide. In total, 35 elements were detected in the samples using electron probe microanalysis. After the treatment, 89.4% of the valuable, toxic, and trace elements gathered in the newly formed matte after maintaining the copper slag for four hours at 1300 °C and adding ferrosilicon. The metallic constituents of slags could be an important source of raw materials and they could be considered an environmentally beneficial source of copper and other materials. Suggested practices can prevent harmful elements from entering the environment, generate value from the gathered metals, and make the remaining slag suitable for construction or mine backfill materials. The present article also assesses the challenges in slag processing by the pyrometallurgical route and provides a roadmap for further investigations and large-scale studies.