An Innovative Approach Toward Enhancing the Environmental and Economic Sustainability of Resource Recovery from Hazardous Zn-Bearing Dusts from Electric Arc Furnace Steelmaking

An innovative approach is reported for recovering Fe and Zn resources from hazardous zinc-bearing electric arc furnace dusts (ZBDs) in a sustainable manner. A combination of carbothermal and H2 reduction were used to overcome challenges associated with the high temperatures of carbothermal reduction and the high costs/limited supplies of hydrogen. In-depth reduction studies were carried out using zinc-rich (17 wt.%), iron-poor (35 wt.%) ZBD; coke oven battery dry quenching dust (CDQD) was used as reductant. Briquettes were prepared by mixing ZBD and CDQD powders in a range of proportions; heat treatments were carried out in flowing H2 gas at 700 °C–900 °C for 4 h. The reduced products were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and inductively coupled plasma (ICP). The Fe content of the reduced briquettes showed increases between 50 and 150%, depending on composition and reduction temperature; Zn, Pb, Cl, Na, K and S were completely absent. The gaseous elements were collected in cooled traps at the furnace outlet to recover metallic zinc and other phases. The volatile products collected at the outlet (900 °C) contained more than 70% zinc and 6% lead; small amounts of zinc were also present in the metallic phase. The processing temperatures were significantly lower in the combined approach as compared to 100% carbothermal reduction. While reducing energy consumption and limiting the generation of greenhouse gases, this approach has the potential for enhancing the reutilization of hazardous industrial wastes, resource recovery, and economic and environmental sustainability.