Influence of bottom-blowing gas species on the nitrogen content in molten steel during the EAF steelmaking process

Abstract

In modern EAF steelmaking process, control of the nitrogen content of molten steel has become more and more important and bottom-blowing technique has been widely applied to promote the molten bath fluid flow, accelerate the metallurgical reaction and improve the quality of molten steel. In this study, the influence of bottom-blowing gas species on the nitrogen content in molten steel during EAF steelmaking was systematically investigated and analysed. Combining the induction furnace experiments and theoretical analysis, the kinetic models of nitrogen change in molten steel with bottom blowing N₂, Ar and CO₂ were established theoretically and validated experimentally. Meanwhile, the thermodynamic laws and agitation capacity of different bottom-blowing gases were also clarified. Then, based on the industrial application research, the metallurgical effects, especially nitrogen removal, with different bottom-blowing gases were also studied and finally, a new concept was proposed for cyclic utilisation of CO₂ in the EAF steelmaking process.