The use of iron carbide for the removal of nitrogen from molten steel

Nitrogen in only small quantities is detrimental to the quality of steel products, particularly with regards to the surface quality and formability of steel strip. Traditionally, the blast furnace (BF)/basic oxygen steelmaking (BOS) route has been favored over the electric arc furnace steelmaking (EAF) route for the production of low carbon strip steels, partially because of the lower nitrogen level steels produced from a BOS furnace (10-40 ppm) compared to what is attainable in an EAF (70-120 ppm). Among the methods for removing dissolved nitrogen from EAF molten steel, the most effective ways are carbon oxidation, and the replacement of scrap with low nitrogen iron bearing materials such as DRI, HBI, iron ore, pig iron and iron carbide. Iron carbide has the significant advantage over other commercially available iron-carbon sources of being easily transportable, as a fine granular material. Injection trials in a number of electric furnaces achieved significant removal of nitrogen. However, there is currently no independent verification of these results nor has any fundamental study of the process been reported in the hterature.