Influence of Phase Transitions on the Macrokinetics of the Gaseous Reduction of Iron Oxide
- Authors: Teplov O.A.1
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Affiliations:
- Baikov Institute of Metallurgy and Materials Science
- Issue: Vol 2018, No 1 (2018)
- Pages: 14-18
- Section: Article
- URL: https://journals.rcsi.science/0036-0295/article/view/172163
- DOI: https://doi.org/10.1134/S0036029518010123
- ID: 172163
Cite item
Abstract
The reduction of magnetite pellets is studied by thermogravimetry in a hydrogen flow upon linear heating. A multiple decrease in the reduction rate is observed at the degrees of metallization higher than 70% in a temperature range of 920–950°C. The observed effect of a decrease in the reduction rate by four to five times on heating is related to the α → γ phase transition of iron. Temperature cycling (heating–holding–heating–holding…) in the phase transition range shows that this effect is reversible; i.e., the reduction rate increases on cooling, unlike that on heating. The average temperature of the beginning of the effect in heating–cooling cycles (913°C) turns out to be close to the thermodynamic temperature (911°C) of the α → γ phase transition of iron. Isothermal studies of the reduction rate of pellets in a temperature range of 900–1000°C also confirm this phenomenon. The effect of a decrease in the reduction rate is assumed to appear due to a decrease in the effective coefficient of gas diffusion in γ-iron as compared to α-iron.
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About the authors
O. A. Teplov
Baikov Institute of Metallurgy and Materials Science
Author for correspondence.
Email: oleg.a.teplov@gmail.com
Russian Federation, Leninskii pr. 49, Moscow, 119991