Decarburization kinetics of Fe-C melt with CO2-O2 mixed gas by isotope tracing method
Article ID: ISIJINT-2022-321
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Article ID: ISIJINT-2022-321
The partial substitution of O2 with CO2 in steelmaking process is an important technology to reduce CO2 emission and recycle. In order to improve CO2-O2 decarburization utilization, the decarburization kinetics of Fe-C melt with CO2-O2 mixed gas have been studied using 13CO2-18O2 dual isotope tracing method and established the decarburization kinetic model. The results show that less than 40% of the oxygen is partially replaced by CO2, which improves the O2 utilization involved in the decarburization reaction and the CO2 utilization is still more than 80%. For the rate limiting steps, regarding O2, it is governed by the mixed control mechanism involving gas-phase mass transfer and interfacial chemical reaction; regarding CO2, with the increase of CO2 partial pressure, the rate limiting step changes from the mixed control to gas-phase mass transfer control only. As bath temperature increase from 1723 to 1873 K, the overall decarburization rate increases; bath temperature mainly affects O2 decarburization rates, whereas, the rates of CO2 are not significantly affected. The apparent activation energy of CO2-O2 mixed gas decarburization is 21.5 kJ·mol-1.
