Effect of Mineral Composition and Pore Structure on Reducibility of Composite Iron Ore Sinter

Abstract

Recently, a new agglomeration concept called MEBIOS (Mosaic EmBedding Iron Ore Sintering) process is proposed. In the process, to utilize the characteristic of the goethite effectively is aimed on the premise of the major use of the goethite ores as a raw material and the low slag content. This is the sintering technology in proportion to the property of the goethite, in which a composite iron ore sinter is formed by arranging the dense pre-granulated pellets properly in the porous induction bed. The use of pisolite and Marra Mamba ores are considered as main components of the porous induction bed and the dense pre-granulated pellets, respectively. In the present study, the composite iron ore sinter, which is composed of the dense pre-granulated pellet and the porous induction bed, is produced experimentally. Only a dense pre-granulated pellet is placed at the center of the porous induction bed. In order to examine what kind of mineral composition and pore structure are desirable from the viewpoint of the reducibility of the composite iron ore sinter, the hydrogen reduction experiments are conducted at 1173 K. The reduction rate of the composite iron ore sinter, which is composed of the dense pre-granulated pellet and the porous induction bed, is larger than the uniform pellet, of which the whole composition is identical. Moreover, the reduction becomes faster by considering the compositional design between the porous induction bed and the dense pre-granulated pellet. It is desirable to contain CaO and SiO₂ more in the porous induction bed than in the dense pre-granulated pellet. From the measurement of the pore-size distribution by the mercury penetration style porosimeter, the reduction is faster for the samples, of which the accumulation pore volume over 10 μm is larger. From the components analysis of the mineral phase, the increase of calcium ferrite in the porous induction bed contributes to the improvement in the reducibility of the composite iron ore sinter.