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.