Desulfurization of Direct-reduced Iron Produced by Heating Iron-ore/Carbon Composite Pellet with Hydrogen and Hydrogen/Water-vapor Gas Mixture

Abstract

The direct-reduced iron produced from iron-ore/coal composite pellet is generally contaminated with sulfur. In this study, iron-ore/coal composite pellet is partially or completely reduced during heating up to given temperatures, 1173 to 1473K, at a constant rate in nitrogen atmosphere. Subsequently, it is treated with H₂-H₂O, H₂, or CO-CO₂ gas mixtures to complete reduction and to perform desulfurization. It is shown that hydrogen treatment is effective to remove the sulfur and water-vapor addition to hydrogen can further enhance the desulfurization kinetically and thermodynamically. The desulfurization rate is very fast and is mainly controlled by chemical reaction on the pore surface of reduced iron. On the other hand, to treat it with a CO-CO₂ gas mixture is almost invalid to desulfurization.