Surface Morphology and Structural Evolution of Magnetite-Based Iron Ore Fines During the Oxidation

The use of magnetite-based iron ore fines by means of fluidized bed technology has become a promising route to produce direct reduced iron. The significant influence of a prior oxidation treatment, which occurs in the preheating stage, on the subsequent fluidization and reduction behavior was observ...

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Bibliographic Details
Published in:Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2022-06, Vol.53 (3), p.1644-1660
Main Authors: Zheng, Heng, Schenk, Johannes, Xu, Runsheng, Daghagheleh, Oday, Spreitzer, Daniel, Wolfinger, Thomas, Yang, Daiwei, Kapelyushin, Yury
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry and Materials Science
Direct reduced iron
Evolution
Ferric oxide
Fluidized beds
Heating
Hematite
High temperature
Iron compounds
Iron ores
Magnetite
Materials Science
Metallic Materials
Morphology
Nanotechnology
Optimization
Original Research Article
Oxidation
Oxidation rate
Phase transitions
Sintering (powder metallurgy)
Structural Materials
Surfaces and Interfaces
Thermogravimetric analysis
Thin Films
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Summary:The use of magnetite-based iron ore fines by means of fluidized bed technology has become a promising route to produce direct reduced iron. The significant influence of a prior oxidation treatment, which occurs in the preheating stage, on the subsequent fluidization and reduction behavior was observed in our previous study. As a result, it is important to investigate the oxidation of magnetite-based iron ore fines for an optimization of the proposed route. Three magnetite-based iron ore brands were analyzed. The oxidation characteristics are investigated based on thermogravimetric analysis. The surface morphology, structural evolution, and phase transformation were studied with a scanning electron microscope, an optical light microscope, and a high-temperature-X-ray diffraction (HT-XRD), respectively. The three samples showed different oxidation capacity indexes (OCIs) but similar TG-DTG curves. The oxidation rate peaks at around 330 °C and 550 °C indicated the formation of γ -Fe 2 O 3 and α -Fe 2 O 3 . The hematite phase shows a particular growth habit. The oxidation first occurs at the surface, forming gridlike hematite structures, and then extends to the inside, resulting in hematite needles. The specific surface area and pore volume decrease significantly due to the sintering effect during oxidation.
ISSN:1073-5615
1543-1916
DOI:10.1007/s11663-022-02475-9