A MATHEMATIC MODEL FOR REDUCTION OF IRON ORE IN MOVING BED

A one-dimensional mathematic model was developed for describing a moving bed reactor in which theiron oxide pellets are reduced to metallic iron with hydrogen and/or CO in a counter-current flow arrangement. The model uses the "three-interface shrinking core model" as the expression of single-pellet reaction kinetics. The model consists of the reaction rate equations of iron oxides and the heat and mass balance equations for both of the gas and the solid streams. The model shows the longitudinal distribution of the process variables such as degree of pellets reduction, and composition, pressure as well as temperature of the gas stream. For the purpose of investigating the reduction process of pellets in a moving bed and checking the correctness of the model, a bench-scale moving bed reactor was established. The experiments were carried out until the steady state was reached. The calculating results based on the model show reasonable agreement with the experimental measuements. The model cart be used for describing an industrial shaft furnace, and shows a difference characteristic between the reduction process of iron ore in a shaft furnace and the reduction process of iron ore under fixed conditions in laboratory.