Conversion of CO2 Gas to CO Gas by the Utilization of Decarburization Reaction during Steelmaking Process

Dissolved carbon in molten iron can be decarburized by CO2 gas instead O-2 gas commonly used in a basic oxygen furnace, in which CO2 gas is reduced to CO gas. Produced CO gas can be returned to iron-making process and as a whole carbon works as energy transfer medium. However, the precise control of the process is required to utilize the decarburization reaction by CO2-O-2 gas mixture because of its significant endothermic reaction. The present study has focused on the decarburization reaction of molten Fe-C alloy by CO2-O-2 or H2O-CO2-O-2 gas mixtures and the effects of gas composition and temperature on temperature change of molten alloy and exhaust gas compositions were studied by means of thermodynamic calculation. Repeated equilibrium calculations between existing molten alloy and newly introduced reacting gas enabled the estimation of molten alloy temperature and exhaust gas composition changes. Results were discussed in terms of molten alloy temperature change and conversion ratio of CO2 to CO or H2O to H-2.