2026 Alajoki Cu Ni Zn Leaching Flash Smelting Dust

Global demand for metals is rising, making industrial side streams a promising feedstock for metals recovery. In the current study, leaching behavior of Cu, Ni, and Zn from Cu flash smelting dust (Cu-FSF) along with impurities (Fe, As, Bi, and Pb) was studied in the absence and presence of Ni flash smelting dust (Ni-FSF). Also, the use of impure lixiviants including waste acids (purified and gas scrubber acid) and wastewater was investigated. The results demonstrate that treating various side streams in a single process can yield synergistic effects. During Cu-FSF leaching in clean acids versus waste acids, Cu leaching yields were similar (78–82% Cu), whereas leaching of Ni and Zn increased slightly (Ni from 41 to 51% and Zn from 70 to 85%). In contrast, when wastewater-derived acid was used, the leaching yield of Bi and As increased substantially (Bi from 3.6 to 99%, As from 66 to 86%) due to high chloride concentration while leaching of Cu, Ni, and Zn was not influenced. Further, simultaneous leaching of Cu-FSF and Ni-FSF was found to promote extractions of Cu, Zn, As, and Pb. The recoveries into PLS increased by 1.6–2.2 times for Cu, Zn, and As, while Pb recovery increased by 4.8 times. Based on the conducted leaching experiments and literature research, synergistic leaching of Cu-FSF and Ni-FSF with waste solutions can create an attractive PLS for Cu, Ni, and Zn precipitation, which can be incorporated into existing refineries, reducing the need for new facilities and enhancing industrial integration and circular economy.