Thermodynamic Study of Energy Consumption and Carbon Dioxide Emission in Ironmaking Process of the Reduction of Iron Oxides by Carbon

Guanyong Sun, Bin Li, Hanjie Guo, Wensheng Yang, Shaoying Li and Jing Guo
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Guanyong Sun: School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
Bin Li: College of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China
Hanjie Guo: School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
Wensheng Yang: School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
Shaoying Li: School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
Jing Guo: School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China

Energies, 2021, vol. 14, issue 7, 1-29

Abstract: Carbon included in coke and coal was used as a reduction agent and fuel in blast furnace (BF) ironmaking processes, which released large quantities of carbon dioxide (CO 2 ). Minimizing the carbon consumption and CO 2 output has always the goal of ironmaking research. In this paper, the reduction reactions of iron oxides by carbon, the gasification reaction of carbon by CO 2, and the coupling reactions were studied by thermodynamic functions, which were derived from isobaric specific heat capacity. The reaction enthalpy at 298 K could not represent the heat value at the other reaction temperature, so the certain temperature should be confirmed by Gibbs frees energy and gas partial pressure. Based on Hess’ law, the energy consumption of the ironmaking process by carbon was calculated in detail. The decrease in the reduction temperature of solid metal iron has been beneficial in reducing the sensible heat required. When the volume ratio of CO to CO 2 in the top gas of the furnace was given as 1.1–1.5, the coupling parameters of carbon gasification were 1.06–1.28 for Fe 2 O 3 , 0.71–0.85 for Fe 3 O 4 , 0.35–0.43 for FeO, respectively. With the increase in the coupling parameters, the volume fraction of CO 2 decreased, and energy consumption and CO 2 output increased. The minimum energy consumption and CO 2 output of liquid iron production were in the reduction reactions with only CO 2 generated, which were 9.952 GJ/t and 1265.854 kg/t from Fe 2 O 3 , 9.761 GJ/t and 1226.799 kg/t from Fe 3 O 4 , 9.007 GJ/t and 1107.368 kg/t from FeO, respectively. Compared with the current energy consumption of 11.65 GJ/t hot metal (HM) and CO 2 output of 1650 kg/tHM of BF, the energy consumption and CO 2 of ironmaking by carbon could reach lower levels by decreasing the coupled gasification reactions, lowering the temperature needed to generate solid Fe and adjusting the iron oxides to improve the iron content in the raw material. This article provides a simplified calculation method to understand the limit of energy consumption and CO 2 output of ironmaking by carbon reduction iron oxides.

Keywords: thermodynamic model; the reduction of iron oxides by carbon; gasification reaction between carbon and carbon dioxide; blast furnace ironmaking process; energy consumption; Hess’s law; reaction enthalpy; carbon dioxide output; relative gas partial pressure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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