Thermodynamic simulation of Bayan Obo lean iron ore under magnetic field
ZHANG Kaixuan1,2,3,4, JIN Yongli1,2,3,4, JIANG Jintao1,2,3,4,, ZHAO Shuhai1,2,3,4
1. School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, Nei Mongol, China; 2. Key Laboratory of Comprehensive Utilization of Ploy metallic Resources in Bayan Obo Mine, Inner Mongolia Automomous Region, Baotou 014010, Nei Mongol, China; 3. National and Local Joint Engineering Research Center for Comprehensive Utilization of Associated Mineral Waste Resources in Bayan Obo, Baotou 014010, Nei Mongol, China; 4. Inner Mongolia Autonomous Regin Carbon Neutralization Collaborecire Innoration Center, Baotou 014010, Nei Mongol, China
Abstract：The magneto-thermodynamic model for carbon thermal reduction of Bayan Obo lean iron ore was developed based on the minimum Gibbs free energy calculation theory. The relationship between temperature and magnetic susceptibility of the main components for Bayan Obo system was determined. Mineral transformation during carbon thermal reaction of Bayan Obo lean iron ore was studied under varying temperature and magnetic field strength to establish theoretical basis for the reaction under magnetic field. The study shows that the magnetic field increases the metallization rate of Fe, reaching maximum at B=0.2 T and t=1 000 ℃. The magnetic field promotes replacement of cations such as Mg2+ and Mn2+ with Fe2+ in silicates, especially at 0.8 T and 1.0 T. For olivine, there is the transition of Fe2SiO4→ (Mg, Mn)FeSiO4→ (Mg, Mn)SiO4 with the intermediate phase (Mg, Mn)FeSiO4 peaking at 0.6 T or 850 ℃. The magnetic field promotes transformation of FeNb2O6 to Ca2Nb2O7, with the theoretical temperature range for the transformation of columbite to pyrochlore (Ca2Nb2O7) without reduction at B=1 T being 774-1 164 ℃. The magnetic field has no significant effect on the content of FeS, TiO2, Ca5(PO4)3F and CaF2. At B=0 T and 800 ℃, TiO2 and FeO form (FeO)2(TiO2). When increasing temperature or magnetic field strength, TiO2 forms CaSiTiO5with CaO and SiO2.
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