Effects of Slag Content and Composition on the Reducibility of Iron Oxide Including CaO-SiO₂-Fe_tO Slag

Abstract

In the sintering with lower slag ratio, the melt quantity decreases, and the agglomeration do not progress sufficiently. It is necessary to secure the melt quantity by silicate melt mainly composed of Fe_xO-SiO₂ system and to control ideally the composition and the generation place of the melt. In the present study, iron ore sinter is simulated by an iron oxide pellet added with (CaO-)SiO₂-Fe_tO slag particles, and the effects of the slag content, the composition, the holding time at 1573 K and the slag particle size on the hydrogen reduction behavior of the iron oxide pellet including (CaO-)SiO₂-Fe_tO slag particles have been investigated at 1173 K. In the initial stage of reduction, the fractional reduction is higher when the slag content is higher. With proceeding the reduction, the fractional reduction of the sample with the higher slag content becomes lower than the sample with the lower slag content. The reduction rate decreases with the increase of the slag content. The ratio of the pore area with over 100 μm pore size increases with the increase of slag content. On the other hand, the final fractional reduction decreases with the increase of the slag content. From this fact, it is considered that the increase of macro pore over 100 μm does not affect on the improvement of reducibility, and the microporosity under 100 μm may become an influential factor. On the slag composition, the final fractional reduction of the pellet including Fe_tO-SiO₂ slag is better. This is because that the silicate slag is difficult to permeate nor block up the pore.