In this study, the isothermal oxidation kinetics of magnetite (OM), high-Mg magnetite (MM), titanomagnetite (TM), and chromite (CM) were investigated by applying thermogravimetry (TG) analysis at temperatures ranging from 1073 K to 1223 K. The results show that different high-FeO spinels possess distinct oxidizability. The oxidation process of OM in the temperature range from 1073 K to 1223 K is faster than others, followed by MM and TM. While CM exhibits the poorest oxidizability, and generally undergoes complex phase transitions. In the initial stage of oxidation, high FeO spinels have a higher oxidation rate due to the surface oxidation of spinel particles. However, the oxidation rate gradually declines in the later stages of oxidation due to increased internal diffusion resistance. The results of oxidation kinetics indicate that the initial oxidation stage of four spinels can be described as random nucleation and subsequent growth mechanism. The average apparent activation energies of the initial oxidation stage of OM, MM, TM, and CM are 25.09 kJ/mol, 32.39 kJ/mol, 58.10 kJ/mol, and 82.42 kJ/mol, respectively.

中文翻译：

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典型高 FeO 亚铁尖晶石的氧化动力学


在本研究中，通过应用热重分析 (TG) 在 1073 K 至 1223 K 的温度范围内研究了磁铁矿 (OM)、高镁磁铁矿 (MM)、钛磁铁矿 (TM) 和铬铁矿 (CM) 的等温氧化动力学结果表明，不同的高FeO尖晶石具有不同的氧化能力。 OM在1073 K~1223 K温度范围内的氧化过程最快，其次是MM和TM。而CM的氧化性最差，并且通常会经历复杂的相变。在氧化初期，由于尖晶石颗粒的表面氧化，高FeO尖晶石具有较高的氧化速率。但在氧化后期，由于内部扩散阻力增加，氧化速率逐渐下降。氧化动力学结果表明，四种尖晶石的初始氧化阶段可以描述为随机成核和随后的生长机制。 OM、MM、TM和CM初始氧化阶段的平均表观活化能分别为25.09 kJ/mol、32.39 kJ/mol、58.10 kJ/mol和82.42 kJ/mol。