Selective removal of zinc and lead from electric arc furnace dust by chlorination–evaporation reactions

• Published in: Journal of hazardous materials Vol. 465; p. 133421
• Main Authors: Hamann, Christopher, Piehl, Patrick, Weingart, Eric, Stolle, Dirk, Al-Sabbagh, Dominik, Ostermann, Markus, Auer, Gerhard, Adam, Christian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.03.2024
• Subjects: Electric arc furnace dust; Hazardous waste; Resource recovery; Selective chlorination; Zinc; Selective chlorination; Resource recovery; Hazardous waste; Electric arc furnace dust; Zinc
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.133421

Re-melting of scrap in an electric arc furnace (EAF) results in the accumulation of filter dust from off-gas treatment that predominantly consists of iron and zinc oxides. Filter dust is classified as hazardous waste due to its high contents of potentially toxic or ecotoxic elements such as Pb, Cr, Cd, and As. A promising processing route for this waste is selective chlorination, in which the non-ferrous metal oxides are chlorinated and selectively evaporated in form of their respective chlorides from the remaining solids via the process gas flow. Here, we investigate stepwise thermochemical treatment of EAF dust with either waste iron(II) chloride solution or hydrochloric acid at 650, 800, and 1100 °C. The Zn and Pb contents of the thermochemically processed EAF dust could be lowered from 29.9% and 1.63% to 0.09% and 0.004%, respectively. Stepwise heating allowed high separation between zinc chloride at the 650 °C step and sodium-, potassium-, and lead-containing chlorides at higher temperatures. Furthermore, the lab-scale results were transferred to the use of an experimental rotary kiln highlighting the possibilities of upscaling the presented process. Selective chlorination of EAF dust with liquid chlorine donors is, therefore, suggested as a potential recycling method for Zn-enriched steelworks dusts. [Display omitted] •Chlorination and thermal treatment are applied to electric arc furnace dusts.•Zinc, lead, cadmium, and other heavy metals are effectively removed.•Two hazardous waste streams are combined for thermochemical recycling.•Zinc chloride and heavy metal depleted iron oxides are formed as valuable products.•The process is upscaled to rotary kiln showing its industrial applicability.