EFFECT OF IRON-ORE SIZE ON KINETICS OF GASEOUS REDUCTION

order to investigate the size effect on the kinetics of the gaseous re duction of iron ore, two kinds of iron oxide pellets of different diam eters were reduced with CO-CO2 gas mixture. Results were analysed usin g two models, Ishida-Wen's model and the unreacted-core model. From th e analysis of the former model, the intraparticle diffusivity through the product layer D-s, the intraparticle diffusivity in the reactant z one D-so and the chemical reaction rate constant based on volume k(v) were not changed with the particle diameter while Thiele's modulus phi and the effectiveness factor E-f were changed. From that of the latte r model, the intraparticle diffusivity through the product layer D-e w as not varied with the particle diameter, while the interface chemical reaction rate constant k(c) was varied. Further investigation reveale d thar k(c) was affected by the diffusion resistance through the produ ct layer, that is, D-s and the particle size as well as the intraparti cle diffusivity in the reactant zone and the reactivity.