Oxidation and Condensation of Zinc Fume From Zn-CO 2 -CO-H 2 O Streams Relevant to Steelmaking Off-Gas Systems
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mol mol 13:7 kJ=mol pZn pH2 O pH2 =Keq;H2 O ¼ 32:9 exp 2 m s RT m2 s
It was proven that a rapid cooling rate (500 K/s) significantly increases the ratio of metallic zinc to zinc oxide as opposed to a slow cooling rate (250 K/s). SEM analysis found evidence of heterogeneous growth of ZnO as well as of homogeneous formation of metallic zinc. The homogeneous nucleation model fit well with experiments where only metallic zinc deposited. An expanded model with rates of oxidation by CO2 and H2O as shown was combined with the homogenous nucleation model and then compared with experimental data. The calculated results based on the model gave a reasonable fit to the measured data. For the conditions used in this study, the rate equations for the oxidation of zinc by carbon dioxide and water vapor as well as the homogeneous nucleation model of metallic zinc were applicable for various temperatures, zinc partial pressures, CO2:CO ratios, and H2O partial pressures. DOI: 10.1007/s11663-016-0910-8 The Minerals, Metals & Materials Society and ASM International 2017
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INTRODUCTION
ELECTRIC arc furnaces (EAF) have become an important part of the steelmaking process in the United States. Over the last 20 years, EAF steel production has
TYLER M. BRONSON is with Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545. Contact e-mail: tybronson@ gmail.com NAIYANG MA is with ArcelorMittal Global R&D East Chicago Laboratories, 3001 E. Columbus Dr., East Chicago, IN 46312. LIANG ZHU ZHU is with the Material Science and Engineering Department, University of Utah, 122 S Central Campus Drive, Room 304, Salt Lake City, UT 84112. HONG YONG SOHN is with the Metallurgical Engineering Department, University of Utah, 135 S 1460 E, Room 412, Salt Lake City, UT 84112. Manuscript submitted June 20, 2016. Article published online January 23, 2017. 908—VOLUME 48B, APRIL 2017
overtaken basic oxygen furnace steel production. Of the 88.2 million metric tons of steel produced in the United States in 2014, 62.6 pct was from EAF. Along with steel production, EAFs also produces EAF dust, a hazardous solid waste. Although EAF dust’s composition is highly variable and dependent on the metal scrap being inputted into the furnace,[1–3] most of the dust has high concentrations of zinc oxide.[2–4] Most shops produce around 11 to 20 kg of EAF dust per ton of steel, or 7500 to 15,000 tons of EAF dust per year.[5] In 2008, NAFTA (North American Free Trade Agreement) countries produced 1,070,300 dry metric tons of EAF dust.[6] EPA regulation classifies EAF dust as a hazardous waste, and only two methods are approved by the EPA for disposing of the dust: to ship the dust to a zinc-recycling facility or to stabilize the dust and then place it in a specially lined METALLURGICAL AND MATERIALS TRANSACTIONS B
hazardous waste landfill.[7] In 1999, 45 pct of the EAF dust in the United States and Canada was landfilled, with 93 pct of this dust being stabilized prior to disposal.[5] Although stabilization and landfilling has previously been the m
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