Use of Hot Metal in Electrical Arc Furnace Jun04

Use of Hot Metal in Electrical Arc Furnace...

Use of Hot Metal in Electrical Arc Furnace Steel making by the electric arc furnace (EAF) has very good flexibility with respect to the selection of charge materials. The traditional charge material for the EAF process has been 100 percent cold scrap but as the issues regarding scrap such as its availability and quality, market price fluctuations and restrictions imposed by scrap in making some steel grades due to residual elements and nitrogen level etc. have increased, EAF operators intensified the search for alternative iron materials. Direct reduced iron (DRI), hot briquetted iron (HBI), pig iron (PI) and hot metal (HM) are the alternative iron materials which have been used in varying percentage successfully by EAF operators. The use of hot metal is more popular in those areas where there is shortage of scrap and/or electric power. The source of hot metal is blast furnace hence hot metal can be used in those EAFs which are in close proximity of the blast furnace, otherwise the EAF operator has to use pig iron. Pig iron will need extra energy for its melting. Presently EAF can be designed for using up to 80 percent of hot metal in the charge. Influence of HM on key parameters of EAF process In recent times the main emphasis in EAF steel making has been related to achieving maximum energy efficiency. Further the feed charge materials are influencing the design of the EAFs and their operation practices. The influence of HM as a charge material on various key parameters of an EAF process of steel making is detailed below. Residual elements – Residual elements also known as tramp elements cannot be removed from the steel during processing. Therefore, the amount of these elements in the product is a direct function...

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...