Nitrogen removal from steel by DRI fines injection

Nitrogen even in small quantities is detrimental to the quality of steel, and it is difficult to remove from steel. The goal of this work was to develop a technique for nitrogen removal from liquid steel by injection of DRI fines. DRI fines, generated either directly from a DRI process or by attrition in transport or handling, contain significant quantities of carbon and oxygen. Studies have shown that upon heating these elements react rapidly inside DRI particles to form fine CO bubbles. The present study examines the generation of CO by the injection of DRI fines; these fines are generated inevitably from the handling and transportation of DRI pellets and briquettes, but such fines could be specifically prepared by crushing DRI pellets. It should be noted that some EAF shops already inject DRI fines to gain some value from this degraded product. To our knowledge there have been no studies to isolate the effect of fines injection, and to optimize this process for nitrogen removal.