Use of Direct Reduced Iron in Electric Arc Furnace May08

Use of Direct Reduced Iron in Electric Arc Furnace...

Use of Direct Reduced Iron in Electric Arc Furnace Electric arc furnace (EAF) operations have improved significantly over the past 30 – 40 years. Future significant improvements will need either new melting technologies or faster power input capabilities. In the meantime steel making in EAFs can benefit significantly from optimizing practices, increasing further the use of chemical energy and correctly using the direct reduced iron (DRI). Historically use of DRI in EAF was for the production of high quality low residuals steels with the anticipated expense of specific energy (kWh/ton), tap to tap time and loss of yield. Current educated use of DRI has developed practices which have demonstrated that DRI use can improve energy consumption, yields, productivity and above all operating costs. Factors related to the Specification of DRI During the production of DRI, oxygen is removed from iron ore reducing it to metallic iron and the more stable oxides such as silica (SiO2), alumina (Al2O3), lime (CaO) and magnesia (MgO) etc. As the oxygen is removed the concentration of these stable oxides increases when compared with their concentration in the feed material for the DRI. Hence the significant issues during steel making by the electric arc furnace (EAF) are as follows. Metallization Carbon content Gangue Non metallics coming with DRI (generally in case of DRI produced by rotary kiln) The chemical composition of the DRI determines such important factors as yield, slag weight, energy consumption, carbon and raw material feeding rates and oxygen usage. Analysis of DRI can vary based on the source and composition of iron ore used for making DRI, the process of making DRI and the process control practiced at the time of making DRI. DRI is available in the composition ranges as given below. Total Fe – 84.5...