TY - JOUR

T1 - Surface Morphology and Structural Evolution of Magnetite-Based Iron Ore Fines During the Oxidation

AU - Zheng, Heng

AU - Schenk, Johannes

AU - Xu, Runsheng

AU - Daghagheleh, Oday

AU - Spreitzer, Daniel

AU - Wolfinger, Thomas

AU - Yang, Daiwei

AU - Kapelyushin, Yury

N1 - Funding Information: The authors gratefully acknowledge the funding support of K1-MET GmbH, metallurgical competence center. The research program of the K1-MET competence center is supported by COMET (Competence Center for Excellent Technologies), the Austrian program for competence centers. COMET is funded by the Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology; the Federal Ministry for Digital and Economic Affairs; the provinces of Upper Austria, Tyrol, and Styria; and the Styrian Business Promotion Agency (SFG). In addition, the research work is partially financed by Montanuniversitaet Leoben. One of the authors (ZH) greatly acknowledges the financial support from the China Scholarship Council program (Grant No. 201908420284). Publisher Copyright: © 2022, The Author(s).

PY - 2022/3/23

Y1 - 2022/3/23

N2 - 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-Fe2O3 and α-Fe2O3. 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.

AB - 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-Fe2O3 and α-Fe2O3. 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.

UR - http://www.scopus.com/inward/record.url?scp=85126887496&partnerID=8YFLogxK

U2 - 10.1007/s11663-022-02475-9

DO - 10.1007/s11663-022-02475-9

M3 - Article

AN - SCOPUS:85126887496

VL - 53.2022

SP - 1644

EP - 1660

JO - Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science

JF - Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science

SN - 1073-5615

IS - 3

ER -