Recycling of an electric arc furnace flue dust to obtain high grade ZnO

• Published in: Journal of hazardous materials 2007-03, Vol.141 (1), p.33-36
• Main Authors: Ruiz, Oscar, Clemente, Carmen, Alonso, Manuel, Alguacil, Francisco Jose
• Format: Article
• Language: English
• Subjects: Ammonium carbonate leaching; Applied sciences; Carbonates - chemical synthesis; Carbonates - chemistry; Cementation; Chemical engineering; Chemical Precipitation; Conservation of Natural Resources; Crystallization, leaching, miscellaneous separations; Dust; Electric arc furnace dust; Exact sciences and technology; Industrial Waste; Pollution; Recycling; Refuse Disposal - methods; Steel; Zinc Compounds - chemical synthesis; Zinc oxide; Zinc Oxide - chemical synthesis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2006.06.079

The production of steel in electric arc furnace (EAF) generates a by-product called EAF dusts. These steelmaking flue dusts are classified in most industrialized countries as hazardous residues because the heavy metals contained in them, tend to leach under slightly acidic rainfall conditions. However, and at the same time they contain zinc species which can be used as a source to obtain valuable by-products. The present investigation shows results on the processing of an EAF flue dust using ammonium carbonate solutions. Once zinc is dissolved: ZnO + 4NH 3 + H 2O → Zn(NH 3) 4 2+ + 2OH − with other impurities (i.e. cadmium and copper), these are eliminated from the zinc solution via cementation with metallic zinc. The purified zinc solution was evaporated (distilled) until precipitation of a zinc carbonate species, which then was calcined to yield a zinc oxide of a high grade. For the unattacked dust residue from the leaching operation, mainly composed of zinc ferrite, several options can be considered: back-recycling to the furnace, further treatment by sodium hydroxide processing or a more safely dumping due to its relatively inertness.