Reduction mechanism of the porous hematite in limonite ore magnetization roasting

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 N-2 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 m(2)/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 Am-2/kg.