Thermodynamic analysis of nitrogen removal in EAF by DRI fines injection

Abstract

Electric arc furnace (EAF) steel typically contains about 70-120 ppm nitrogen, yet for some bar and flat rolled products, the maximum limit of nitrogen is 30 ppm. Nitrogen removal from steel is very difficult through vacuum degassing or inert gas purging, because of its low diffusivity, hence nitrogen removal is one of the major challenges to EAF operators. In the present study, direct reduced iron (DRI) fines have been injected into the steel bath which generates fine CO gas bubbles deep in the bath which help to remove dissolved nitrogen. Experimentation has been carried out in an indirect EAF on a 15 kg scale. Nitrogen removal has been found to be a very good in high carbon steel