TY - JOUR
T1 - Effect of hydrogen concentration in reducing gas on the changes in mineral phases during reduction of iron ore sinter
AU - MURAKAMI, Taichi
AU - WAKABAYASHI, Hiroki
AU - MARUOKA, Daisuke
AU - KASAI, Eiki
N1 - Funding Information:
The present work was carried out as a part of COURSE50 project. Financial support by the New Energy and Industrial Technology Development Organization (NEDO) is gratefully acknowledged. The authors greatly appreciate the experimental work of Mr. H. Hoshino, and Mr. S. Yamazaki who are past members of our laboratory in Tohoku University.
Publisher Copyright:
© 2020 The Iron and Steel Institute of Japan.
PY - 2020/12/15
Y1 - 2020/12/15
N2 - In order to decrease CO2 emission from the ironmaking process, an increasing use of hydrogen in blast furnace (BF) ironmaking is a promising way. In this case, the properties of iron ore sinter such as reducibility and strength need to be optimized because hydrogen reduction of iron oxide is an endothermic reaction and temperature distribution in BF drastically changes. In this study, the effect of hydrogen concentration in the reducing gas on the changes in mineral phases during reduction of iron ore sinter is evaluated. Mineral composition of the ten types of sinter samples was analyzed by XRD and image analysis. Sinter sample was reduced under the simulated conditions such as Low-H2 (N2 - 48%(CO + CO2) - 5.8%(H2 + H2O)) and High-H2 (N2 - 48%(CO + CO2) - 13%(H2 + H2O)). After reduction, microstructure of the sample was observed. Iron ore sinters usually consist of mineral phases such as hematite, magnetite, calcium-ferrites and slag. Furthermore, calcium-ferrite phases are roughly divided into four types: 1) acicular texture coexisted with primary hematite (1H-ACF), 2) columnar texture coexisted with secondary hematite (2H-CF), 3) small and 4) large columnar textures coexisted with magnetite (M-FCF and M-CCF). An increase in hydrogen concentration of reducing gas accelerates the reduction of hematite, 1H-ACF, and 2H-CF in all sinter samples, while it does not affect the reduction of magnetite, and calcium-ferrite coexisted with magnetite.
AB - In order to decrease CO2 emission from the ironmaking process, an increasing use of hydrogen in blast furnace (BF) ironmaking is a promising way. In this case, the properties of iron ore sinter such as reducibility and strength need to be optimized because hydrogen reduction of iron oxide is an endothermic reaction and temperature distribution in BF drastically changes. In this study, the effect of hydrogen concentration in the reducing gas on the changes in mineral phases during reduction of iron ore sinter is evaluated. Mineral composition of the ten types of sinter samples was analyzed by XRD and image analysis. Sinter sample was reduced under the simulated conditions such as Low-H2 (N2 - 48%(CO + CO2) - 5.8%(H2 + H2O)) and High-H2 (N2 - 48%(CO + CO2) - 13%(H2 + H2O)). After reduction, microstructure of the sample was observed. Iron ore sinters usually consist of mineral phases such as hematite, magnetite, calcium-ferrites and slag. Furthermore, calcium-ferrite phases are roughly divided into four types: 1) acicular texture coexisted with primary hematite (1H-ACF), 2) columnar texture coexisted with secondary hematite (2H-CF), 3) small and 4) large columnar textures coexisted with magnetite (M-FCF and M-CCF). An increase in hydrogen concentration of reducing gas accelerates the reduction of hematite, 1H-ACF, and 2H-CF in all sinter samples, while it does not affect the reduction of magnetite, and calcium-ferrite coexisted with magnetite.
KW - Calcium ferrite
KW - Hydrogen
KW - Reduction
KW - Sinter
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U2 - 10.2355/isijinternational.ISIJINT-2020-180
DO - 10.2355/isijinternational.ISIJINT-2020-180
M3 - Article
AN - SCOPUS:85098116622
SN - 0915-1559
VL - 60
SP - 2678
EP - 2685
JO - ISIJ International
JF - ISIJ International
IS - 12
ER -