Effects of temperature and [S] on the kinetics of nitrogen removal from liquid steel

The kinetics of denitrogenation from liquid steel was studied by using an o xygen-nitrogen analysis system(LECO TC-436) under 1600 degreesC similar to 2813 degreesC conditions. The results show that when [S]=0.005%, nitrogen r emoval was controlled by nitrogen transfer in liquid diffusion layer, when [S]=0.012% and 0.140%, it was controlled by both nitrogen transfer in liqui d diffusion layer and the chemical reaction at the liquid-gas interface bel ow 2250 degreesC, and by nitrogen transfer in liquid diffusion layer under 2250 degreesC similar to 2813 degreesC conditions. The activation energy E- a was 57 kJ/mol for 0.0050%[S], 95 kJ/mol for 0.012%[S], 165 kJ/mol for 0.1 40%[S]. The resistance of sulphur on nitrogen removal decreased with the te mperature rose, and disappeared at 2630 degreesC. Based on the results obta ined, it has been answered why the nitrogen in liquid steel can be decrease d rapidly by carbon-oxygen reaction under very high oxygen and sulphur cont ent conditions during the BOF, EAF, VOD and AOD steelmaking processes.