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

Abstract

The iron and steel industry is one of the main sources of global carbon emissions, and the development of new technologies for CO₂ resource utilisation is crucial for achieving the ‘double carbon’ goal. In this article, the decarbonisation of CO₂ in steel refining and its thermodynamic mechanism is investigated, and the effects of initial carbon content, smelting temperature and CO₂ blowing flow rate on the decarbonisation effect are analysed by combining with Factsage calculations and high-temperature experiments. The reaction involved in the CO₂ 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 CO₂ 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. CO₂ 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.