University of Oulu

Iljana, M., Mattila, O., Alatarvas, T., Visuri, V., Kurikkala, J., Paananen, T., Fabritius, T. (2012) Dynamic and Isothermal Reduction Swelling Behaviour of Olivine and Acid Iron Ore Pellets under Simulated Blast Furnace Shaft Conditions. ISIJ International, 52 (7), 1257-1265.

Dynamic and isothermal reduction swelling behaviour of olivine and acid iron ore pellets under simulated blast furnace shaft conditions

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Author: Iljana, Mikko1; Mattila, Olli2; Alatarvas, Tuomas1;
Organizations: 1University of Oulu, Laboratory of Process Metallurgy, PO Box 4300, University of Oulu, FI-90014 Finland
2Ruukki Metals Oy, Rautaruukintie 155, Raahe, FI-92100 Finland
3Boliden Harjavalta Oy, Teollisuuskatu 1, Harjavalta, FI-29200 Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.6 MB)
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Language: English
Published: Iron and Steel Institute of Japan, 2012
Publish Date: 2021-01-20


Pellet swelling has been widely studied, being simultaneous with reduction reactions and common in the operation of blast furnaces. A tube furnace equipped with a camera recording system was used here to study the dynamic and isothermal reduction swelling behaviour of olivine and acid pellets under simulated BF shaft conditions. The olivine pellets were magnetically separated into three fractions, containing low, medium and high amounts of magnetite in the core. The divalent iron (FeO) content of these fractions was 0.1 wt-%, 0.2 wt-% and 2.9 wt-%, respectively. Pellets with a large magnetite nucleus were observed to encompass numerous cracks, which was reflected in a poor LTD test value, while SiO₂-rich reference pellets with a different slag chemistry had more restrained swelling and cracking behaviour in dynamic reduction. Swelling in the olivine pellets was associated with cracking at the boundary between the original magnetite nucleus and the hematite shell.

The dynamic reduction swelling test results showed lower reduction swelling indices (max 17% in volume) than under isothermal conditions (max 51% in volume), in which case the pellets were suddenly exposed to a strongly reducing atmosphere. It is thus suggested that the reduction swelling behaviour of iron ore pellets should preferably be studied dynamically under simulated blast furnace conditions in order to achieve a realistic understanding of their swelling behaviour in a blast furnace.

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Series: ISIJ international
ISSN: 0915-1559
ISSN-E: 1347-5460
ISSN-L: 0915-1559
Volume: 52
Issue: 7
Pages: 1257 - 1265
DOI: 10.2355/isijinternational.52.1257
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: Ruukki Metals Oy and the Finnish Funding Agency for Technology and Innovation (TEKES) are acknowledged for funding this work.
Copyright information: © 2012 by The Iron and Steel Institute of Japan.