METALS AND MATERIALS International, Vol. 10, No. 5 (2004), pp. 493~500 Mathematical Model of Thermal Processes in an Iron Ore Sintering Bed Won Yang 1 , Changkook Ryu 2 , Sangmin Choi 1, * , Eungsoo Choi 3 , Deog Won Ri 3 , and Wanwook Huh 3 1 Department of Mechanical Engineering Korea Advanced Institute of Science and Technology 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea 2 Department of Chemical Process Engineering, University of Sheffield 3 Technical Research Laboratory, POSCO 5 Dongchon-dong, Nam-gu, Pohang 790-785, Korea An unsteady one-dimensional model of an iron ore sintering bed with multiple solid phases was proposed. The proposed model confers a phase on each solid material. The present model was established with a series of conservation equations in the form of a partial differential equation for each solid phase and gas phase. Coke combustion, limestone decomposition, gaseous reaction, heat transfers in/between each phase, and geo- metric changes of the solid particles are reflected by each term of the governing equations. Simulation results are compared with the limited experimental data set of sintering pot tests. Parametric studies for various initial water contents and coke diameters have also been performed. The simulation results predict the exper- imental results well and show physically reasonable trends for various parameters. Keywords: iron ore sintering, coke combustion, heat transfer, modeling, sintering pot test 1. INTRODUCTION Computational analyses of iron-making facilities, which are comprised of a coke oven and sintering and blast furnace processes, constitute one of the major research fields in the steel industry for improvement of operating conditions, pro- ductivity, and energy efficiency [1,2]. An iron ore sintering process is applied to produce large particles (>~5 mm) of iron ore agglomerates with appropriate metallurgical proper- ties required in the blast furnace. A raw mix of iron ores, limestone, and fuel coke fines forms a bed on a traveling grate. Fig. 1 shows a conceptual version of the process in the iron ore sintering bed. Once ignited by a coke oven gas (COG) burner, coke combustion progresses downward very slowly, and iron ores are sintered in the high temperature (combustion) zone. Air is supplied to the bed by a down draft suction fan. The combustion commences at the top of the bed by a hot gas jet from the ignition burners for a few minutes after the feed material is introduced into the bed, and propagates into the bed with sintering near the combus- tion front. Many researchers have strived to build an accurate mathe- matical model of coke combustion and heat transfer in the iron ore sintering bed [3-10]. However, there is still room for improvement of the models in terms of solid fuel combus- tion and heat transfer in a porous media, whereas the pro- posed models adequately describe these complicated pheno- mena in the sintering bed. In addition, effects of variation of the solid composition and operating parameters should be ana- lyzed carefully. In this research, simulations of the iron ore sintering process have been developed, considering multiple solid phases and employing a series of conservation equa- tions for each phase. Reactions and heat transfer in/between identical/different solid phases are developed for calculating source terms of the conservation equations. Geometrical changes of the solid particles and structural change of the bed are modeled in an improved manner. Simulations are performed for various compositions of solid material and coke diameters. The computed results are compared with the limited set of sintering pot test results. 2. COMPUTATIONAL MODELING The sintering bed consists of a gas phase and multiple solid phases including iron ores, coke, limestone, and other minor additives. The mixture of the solid phases can be con- sidered as a homogeneous medium of all the component spe- cies. Each solid phase may be of a different particle size and chemical composition. When heated by a hot gas stream generated by a gas burner, solid material experiences drying, coke reactions, limestone decomposition, or reduction of the iron oxide. For large particles, multiple kinds of reactions *Corresponding author: smchoi@kaist.ac.kr