Reduction-swelling behaviour of pellets bearing iron ore and charcoal

Self-reducing pellets containing iron ore and charcoal were reduced under argon at 1123, 1273, 1323, 1373, and 1423 K. The pellets were cold bonded with Portland cement. Pellets measuring 9.1 and 15.3 mm diameter were tested. Thermogravimetry was used to follow the reduction process. X-ray diffracti...

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Bibliographic Details
Published in:Canadian metallurgical quarterly 1998-12, Vol.37 (5), p.441-448
Main Authors: Nascimento, Ramiro Conceicao, Mourão, Marcelo Breda, Capocchi, José Deodoro Trani
Format: Article
Language:English
Subjects:
Applied sciences
Direct reduction
Exact sciences and technology
Iron and steel making
Metals. Metallurgy
Production of metals
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Summary:Self-reducing pellets containing iron ore and charcoal were reduced under argon at 1123, 1273, 1323, 1373, and 1423 K. The pellets were cold bonded with Portland cement. Pellets measuring 9.1 and 15.3 mm diameter were tested. Thermogravimetry was used to follow the reduction process. X-ray diffraction was used to identify the present phases at the different steps of the reduction reaction. The change in volume was related to the reaction fraction, reaction temperature and the size of the pellet. Scanning electron microscopy images of the reduced pellet have shown that swelling is due to the formation of whiskers of iron during the wüstite to iron step of reduction.Rétésumété- Des pelotes auto-reductrices faites de minerais de fer et de charbon ont été réduites sous atmosphère dargon à temperatures de 1123, 1273, 1323, 1373, et de 1423 K. Les pelotes furent liées à froid avec un ciment Portland. Des pelotes mesurant de 9,1 a 15,3 mm furent étudiées. Afin détudier lévolution de la réduction, des analises thermogravimetriques furent performées. La technique de diffraction de rayons X fut utilisée pour identifier les différentes phases présentes au cours des differentes étapes de la réaction de réduction. Le changement de volume fut relié à lavancement de la réaction, la temperature de la reaction et à la taille de la pelote. Des observations avec microscope a balayage des pelotes ont révelé que le changement de volume était du a la formation de fibres de fer au cours de la wüstite de la reduction du minerais de fer. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.
ISSN:0008-4433
1879-1395
DOI:10.1016/S0008-4433(98)00021-4