Abstract
Staged reduction kinetics and characteristics of iron oxide direct reduction by carbon were studied in this work. The characteristics were investigated by simultaneous thermogravimetric analysis, X-ray diffraction (XRD), and quadrupole mass spectrometry. The kinetics parameters of the reduction stages were obtained by isoconversional (model-free) methods. Three stages in the reduction are Fe2O3→Fe3O4, Fe3O4→FeO, and FeO→Fe, which start at 912 K, 1255 K, and 1397 K, respectively. The CO content in the evolved gas is lower than the CO2 content in the Fe2O3→Fe3O4 stage but is substantially greater than the CO2 contents in the Fe3O4→FeO and FeO→Fe stages, where gasification starts at approximately 1205 K. The activation energy (E) of the three stages are 126–309 kJ/mol, 628 kJ/mol, and 648 kJ/mol, respectively. The restrictive step of the total reduction is FeO→Fe. If the rate of the total reduction is to be improved, the rate of the FeO→Fe reduction should be improved first. The activation energy of the first stage is much lower than those of the latter two stages because of carbon gasification. Carbon gasification and Fe x O y reduction by CO, which are the restrictive step in the last two stages, require further study.
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Wei, Rf., Cang, Dq., Zhang, Ll. et al. Staged reaction kinetics and characteristics of iron oxide direct reduction by carbon. Int J Miner Metall Mater 22, 1025–1032 (2015). https://doi.org/10.1007/s12613-015-1164-1
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DOI: https://doi.org/10.1007/s12613-015-1164-1