首页|Temperature Dependence of Reduction Disintegration of Self-fluxing Pellet under High Hydrogen Condition of Blast Furnace

Temperature Dependence of Reduction Disintegration of Self-fluxing Pellet under High Hydrogen Condition of Blast Furnace

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It has been reported that an increasing H_2 gas ratio of the reducing gas in the blast furnace promotes the low temperature reduction disintegration of the iron ore pellet. Reduction of the pellet sample proceeds uniformly under higher H_2 condition at 500℃. Microcracks with the size of several micrometer form at the primary particles of iron oxide and it promote fine particles formation after the drum test. Macrocracks with the size of several millimeter form inside of the pellet after reduction and it promotes the volumetric destruction. In this study, the temperature dependence of reduction disintegration of self-fluxing pellet under higher H_2 condition was examined. Pellet sample was reduced under CO and CO-H_2 gas conditions at 600℃ and 700℃. After reduction, the disintegration test was conducted using the drum. Under higher H_2 condition at 600℃, the density of microcracks decreases with increasing reduction degree and it leads to lower of the RDI value than that at 500℃. The reason is that the volumetric expansion by the reduction from hematite to magnetite at 600℃ is not significant compared with that at 500℃. The difference of reduction degree at the center and near the surface of the pellet increases with increasing the reduction temperature. Reduction reaction proceeds more topochemically by increasing reduction temperature and the addition of hydrogen. This change leads the macrocrack formation, which is same mechanism under CO gas condition at 500℃. At 700℃, on the other hand, this microcrack was not observed because the volumetric expansion by the reduction is lower than that at lower temperature. Therefore, the effect of hydrogen addition on disintegration is not significant at 700℃.

iron makingreduction disintegrationhydrogen enriched blast furnaceiron ore pelletparticle distributionCT image

Koki MOMMA、Daisuke MARUOKA、Eiki KASAI、Taichi MURAKAMI

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Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8579 Japan

Graduate School of Environmental Studies, Tohoku University. Now at Material and Biological Engineering Course, National Institute of Technology, Hachinohe College, 16-1, Uwanotai, Tamonoki, Hachinohe, Aomori, 039-1192 Japan

2025

10.2355/isijinternational.ISIJINT-2024-356

ISIJ international

ISIJ international

ISSN：0915-1559
年,卷(期)：2025.65(6)