Behavior of Zn and Fe Content in Electric Arc Furnace Dust as Submitted to Chlorination Methods
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ONE of the main challenges for non-integrated steel plants in Brazil and abroad is to mitigate the main effects from the generation of solid residues in electric furnaces. Several studies present solutions for this problem, some of these where the residue may be reused within the company itself. In most cases, this material, many times identified just as ‘‘electric arc furnace dust’’ cannot be directly recycled due, mainly, to the high zinc content.[1] The typical EAF dust composition values, found in literature, for these dusts are 18 to 40 pct Fe, 10 to FELIPE SANTOS, formerly M.Sc. Student with the Chemical and Materials Engineering Department, Pontifical Catholic University of Rio de Janeiro, Rua Marqueˆs de Sa˜o Vicente, 225, CEP: 22453-900, Rio de Janeiro, RJ, Brazil, is now D.Sc. Student with the Institute of Chemistry, UFRJ, Rio de Janeiro, Brazil. EDUARDO BROCCHI, Professor, and RODRIGO SOUZA, D.Sc. Student, are with the Chemical and Materials Engineering Department, Pontifical Catholic University of Rio de Janeiro. Contact e-mail: [email protected] VICTOR ARAU´JO, formerly Undergraduate Student with the Chemical and Materials Engineering Department, Pontifical Catholic University of Rio de Janeiro, is now Executive with the GE Transportation, Belo Horizonte, Brazil. Manuscript submitted August 16, 2014. METALLURGICAL AND MATERIALS TRANSACTIONS B
35 pct Zn, 1 to 6 pct Pb, 0.4 to 0.5 pct Al, 3 to 4 pct Ca and, in some cases, 0.02 to 0.9 pct Cd, 0.1 to 0.8 pct As, and 0.1 to 0.8 pct Cr.[2–5] It is noteworthy to mention that, according to the technical standards currently applied in[6] and Brazil,[7] this material is classified as hazardous one and can only be sent to landfills in some specific conditions and thus stimulating research associated with methods to diminish this requirement. However, only a few a technologies have succeeded in this initiative so far, as the Waelz kiln continues to be the main method to process the electric arc furnace dust.[8] Nevertheless, this process requires the dust with some specific characteristics (e.g., high zinc content) to be properly operated. So, it is still a kind of challenge to appraise new alternatives in order to minimize the impact of the electric arc furnace dust generation, particularly when the Waelz kiln route is not applicable. The residue in question deserves, then, specific approaches, such as controlling the dust components, appropriate disposal, or processing methods, which makes its recycling possible. Analyzing each one of the alternatives, it is observed that controlling the source is hard to implement, considering that the furnaces are fed with scrap of great diversity. The disposal, besides the cost involved, demands immense
Fig. 1—Gibbs free energy variation: Direct action of chlorine over zinc ferrite.
Fig. 2—Gibbs Free Energy Variation: Direct action of chlorine over Fe and Zn oxides.
storage areas. Therefore, treatments followed by a proper reuse remains are a subject of great interest, and a variety of works has been cited in the literatu
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