Determination of interfacial reaction rate constant of nitrogen between N₂-CO₂-CO-Ar and molten iron using isotope exchange technique

The application of CO₂ in the steelmaking process has yielded promising results, demonstrating a certain capability for nitrogen removal. To accurately determine the kinetic parameters of nitrogen reactions at the iron melt interface under CO₂ injection conditions, an isotope exchange technique was employed. This technique was used to monitor the evolution of the nitrogen isotopic composition during the reaction between a ²⁸N₂-³⁰N₂-CO₂-CO-Ar gas mixture and an iron melt of controlled composition. The kinetic parameters of nitrogen were subsequently calculated for various CO₂/CO ratios. Furthermore, the dissociation rate determining model was applied to establish the relationship between the interfacial reaction rate constant and the activity of surfactive elements (O, C, and S) in molten iron, expressed as: k_c=4.35×10^-6/(1+14.25a_O+0.25a_C+6.50a_S)²