Effects of Iron Ore Porosity on Its Reduction and Iron Carbide Formation
铁矿石孔隙度对其还原和碳化铁生成的影响

The formation process of iron carbide from iron ore by reduction and carburization with 70%H2-30%CH4 gas mixture was studied using thermogravimetric measurement, XRD and EDX analysis. The micropore distribution in the iron ores and their reduced product, iron, was measured. It was observed that the reduction and carburization rates were quite different among the iron ores with different microstructures. The Brazil lump ore, Australia lump ore and South Africa pellet ore can be reduced completely in 50 min, and then carburized. But iron carbide cannot form from the South Africa lump ore, even though it can be reduced to iron in 90 min. The reduction rate of porous iron ore was fast and the structure of formed iron was also porous and abundant in micropores, being favourable to the reaction of carburization. After the reduction, the volume distribution of 0.5-3.5 nm micropores increased doubly, the tendency of the micropore size distribution is similar to that in iron ores, especially, the volume distribution of 3.5-13 nm micropore increased notablely. The micropore size and volume distribution have large effect on the ore reduction rate and the reaction of iron carbide formation.