Finding New Life for Tailings: Sustainable Technology for Co, Cu, Ni, and Zn Production

Current and future social imbalances such as increasing metals demand for electromobility, need for CO₂-free electrical power, reduction of mine wastes, and declining supply of elemental sulfur from oil and gas production all can be compensated for by efficient recycling of tailings. Upgrading tailings into a pyrite concentrate allows for valuable metals recovery through a combination of long-proven and modern technologies. Used primarily for the production of sulfuric acid up to the 1970s, the mining industry is now revisiting pyrite roasting technology to process existing waste materials. The latest reference plant for this technology is Eti Gübre Mazidagi in Turkey, a highly integrated industrial complex that created multiple revenue and value streams, using a sustainable approach to metals (cobalt, copper, zinc, gold, and silver) recovery, acid production, and finally steam and electric power production with no CO₂ emissions. Over the last 70 years, Metso Outotec has built more than 160 pyrite roasters, whose success has proven the efficacy of the pyrite roasting process. The paper describes typical key parameters required for comparing potential small and large investment projects.