Effect of surface active elements on nitrogen reaction with iron melts

Experimental results of denitrogenation of pure iron melts were expressed as a first or second order reaction, respectively. It was concluded that, at [O] and [S] contents in the range 80-800 ppm, both diffusion in the liquid and interfacial reaction control nitrogen transfer. A mixed control model is presented where the two rate controlling steps are involved. The mass transfer rate constants β c and β l were used to describe the nitrogen reaction. It was found that the coefficient β l is influenced by surface active elements, mainly oxygen and sulphur. Finally, an overall reaction coefficient β ov was evaluated as a function of the coefficients β c and β l and of the nitrogen content in the iron melt.