Oxygen-assisted zinc recovery from electric arc furnace dust using magnesium chloride

Electric arc furnace (EAF) dust is an important secondary resource containing metals, such as zinc (Zn) and iron (Fe). Recovering Zn from EAF dust can contribute to resource recycling and reduce environmental impacts. However, the high chemical stability of ZnFe2O4 in EAF dust poses challenges to Zn recovery. To address this issue, a facile approach that involves oxygen-assisted chlorination using molten MgCl2 is proposed. This work focused on elucidating the role of O2 in the reaction between ZnFe2O4 and molten MgCl2. The results demonstrate that MgCl2 effectively broke down the ZnFe2O4 structure, and the high O2 atmosphere considerably promoted the separation of Zn from other components in the form of ZnCl2. The presence of O2 facilitated the formation of MgFe2O4, which stabilized Fe and prevented its chlorination. Furthermore, the excessive use of MgCl2 resulted in increased evaporation loss, and high temperatures promoted the rapid separation of Zn. Building on these findings, we successfully extracted ZnCl2-enriched volatiles from practical EAF dust through oxygen-assisted chlorination. Under optimized conditions, this method achieved exceptional Zn chlorination percentage of over 97% within a short period, while Fe chlorination remained below 1%. The resulting volatiles contained 85wt% of ZnCl2, which can be further processed to produce metallic Zn. The findings offer guidance for the selective recovery of valuable metals, particularly from solid wastes such as EAF dust.