Study on the mechanism of CO ₂ participation in the decarburisation reaction of Fe–C alloys

The iron and steel industry is one of the main sources of global carbon emissions, and the development of new technologies for CO 2 resource utilisation is crucial for achieving the ‘double carbon’ goal. In this article, the decarbonisation of CO 2 in steel refining and its thermodynamic mechanism is investigated, and the effects of initial carbon content, smelting temperature and CO 2 blowing flow rate on the decarbonisation effect are analysed by combining with Factsage calculations and high-temperature experiments. The reaction involved in the CO 2 can mildly control the molten pool temperature, and decarbonisation is a three-phase coupled process of gas-slag-metal with the elemental mass transfer of carbon as a rate-controlling link. It was found that the decarburisation rate was accelerated with the increase of carbon content when the initial carbon content was more than 0.11%; the larger the CO 2 blowing flow rate, the faster the decarburisation rate; the temperature has less influence on decarburisation, but the temperature rise in low carbon steel liquid can improve the decarburisation rate. CO 2 can be used as an effective decarburising agent, and optimisation of the parameters can increase the decarburisation efficiency, and help reduce the emission of the iron and steel industry.