The effective parameters on thermal recovery and reduction of iron oxides in EAF slag

Document Type: Research Paper

Authors

Department of Materials Engineering, Islamic Azad University of Najafabad, Iran

Abstract

Steelmaking slag of Mobarakeh Steel Company (MSC) has a high iron content which makes it unsuitable for conventional slag recovery; as in cement industries. On the other hand, EAF slag in this company is almost free of zinc because of using more than 90 percent DRI in the charge. Therefore, removal or recovery of iron from the slag can be a suitable solution to slag recovery in this company. In this research work, cold bonded briquette was made from mixtures of milled slag and coke breeze. The effect of binder content on the strength of the briquettes was studied. The reduction of iron oxides was also investigated by heating up the briquettes in a muffle furnace. The results indicated that using 4wt% sodium silicate as binder leads to reasonable compression strength of about 1500kg although the strength could be increased to as high as 2000kg by using 6wt% binder. Up to 40% reduction, the reducing rate was almost high; then it decreased and reached a minimum value at 70% reduction. Using extra carbon than the reaction stoichiometry didn’t have significant effect on the reduction. Temperatures above 1000°C up to 1200°C had also a small positive effect on the reduction rate. When reduction was performed at 1000°C, for 180min, semi-reduced material (70% reduced) could be obtained, which can be used (cold or hot) in BOF or other steelmaking processes.

]1[ H. Shen, E. Forsberg: Waste. Manage. 23 (2003), 933.]2[ S.K. Kawatra, S.J. Ripke: Int. J. Miner. Process. 65 (2002), 165.]3[ M. Maslehuddin, A.M. Sharif, M. Shameem: Constr. Build. Mater. 17 (2003), 105.]4[ A. Monshi, M.K. Asgarani: Cement. Concrete. Res. 29 (1999), 1373.]5[ H. Alanyali, M. C. Yılmaz, S. Karago¨z: Waste Manage. 26 (2006), 1133.]6[ H. K. Chen Lin, SH. Liu: Scand J Metallurgy: 21 (1992), 218.]7[ M. Rahman, R. Haque and M.M. Haque: Ironmak. & Steelmak: 22 (1995), 166.]8[ S. Mookherjee, H.S. Ray and A. Mukherjee: Ironmak. Steelmak: 13(1986), 229.]9[ T. Sharma: Int. J. Miner. Process. 39 (1993), 299