Reduction mechanism of the porous hematite in limonite ore magnetization roasting

ABSTRACT

Magnetization roasting is an effective method to treat limonite ore. However, the reduction mechanism of limonite ore after dehydroxylation needs further investigation. In this study, magnetization roasting of limonite ore was conducted using a fluidized reactor, and the reduction mechanism of the porous hematite was studied. The microporosity, reduction process, and magnetism variation were studied using the Brunauer–Emmett–Teller method with N₂ adsorption, kinetic analysis, and vibrating sample magnetometry. The results indicated that microporosity was present in the synthetic hematite due to the dehydroxylation of goethite ore, and the specific surface area increased from 18.46 to 53.30 m²/g, which was conducive to the reduction of hematite to magnetite. The reduction mechanism of the porous hematite to magnetite followed the nucleation model A_3/2, and the calculated activation energy was 18.43 kJ/mol. The saturation magnetization of the synthetic magnetite was 60.19 Am²/kg.

KEYWORDS:

• Limonite, reduction
• kinetics
• porous hematite
• microporosity

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors thank the National Natural Science Foundation of China [Nos. 52104249 and 51734005], China Postdoctoral Science Foundation Funded Project [No. 2021M700726], and the National Key Research and Development Program of China [Grant No. 2021YFC2902401] for financial support.