Thermal decomposition behaviour and kinetics of Xinjiang siderite ore
Thermal decomposition behaviour and kinetics of Xinjiang siderite ore
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DOI：
10.1080/03719553.2015.1118213
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发表时间：
2016-01
期刊：
影响因子：
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通讯作者：
Yan-hong Luo;D. Zhu;J. Pan;Xianlin Zhou
中科院分区：
文献类型：
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作者：
Yan-hong Luo;D. Zhu;J. Pan;Xianlin Zhou
为了给新疆中国菱铁矿资源的开发利用提供更好的理论依据，采用热力学分析、化学滴定、热重和X射线衍射等手段，研究了新疆菱铁矿在中性和氧化性气氛中的热分解行为。通过等温实验研究了菱铁矿在500~850℃弱氧化气氛中的热分解动力学。结果表明，菱铁矿在受控条件下具有自磁化特性，其相变过程和最终分解产物依赖于温度和气氛。在弱氧化气氛下的相变过程为：FeCO3→Fe3O4→γ-Fe2O3550℃和FeCO3→FeO+Fe3O4→Fe3O4→γ-Fe2O4→α-Fe2O3。在惰性气氛中，733℃以下的分解途径为FeCO3→Fe3O4,733℃以上的分解途径为FeCO3→FeO+Fe3O4。菱铁矿块体在缺氧气氛中的分解动力学在5 0 0~70 0℃符合化学反应控制，在75 0~85 0℃符合成核生长机制，相应的活化能分别为5 3·73和38·15KJ·−1。
In order to provide a better theoretical foundation for utilisation of Xinjiang siderite resources in China, its thermal decomposition behaviour was studied in neutral and oxidising atmospheres by employing thermodynamics analysis, chemical titration, thermogravimetric, and X-ray diffraction means. Isothermal experiments were conducted to investigate the thermal decomposition kinetics of siderite lump in a weakly oxidising atmosphere at 500–850°C. The results reveal that siderite has self-magnetisation characteristics under controlled conditions, and the phase evolution process and final products of decomposition depend temperature and atmosphere. The phase transformation process in weak oxidising atmosphere follows the steps as: FeCO3 → Fe3O4 → γ-Fe2O3 at 550°C, and FeCO3 → FeO + Fe3O4 → Fe3O4 → γ-Fe2O3 → α-Fe2O3 at 800°C. In inert atmosphere, the decomposition pathway is FeCO3 → Fe3O4 below 733°C and FeCO3 → FeO + Fe3O4 above 733°C. The molar ratio of FeO/Fe3O4 increases with temperature. The decomposition kinetics of siderite lump in oxygen-deficient atmosphere is consistent with chemical reaction control in the temperature range 500–700°C and nucleation and growth mechanism in the 750–850°C. The corresponding activation energies are 53·73 and 38·15 KJ mol−1, respectively.