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Rende Chang, Chengyi Ding, Hongming Long, Xuewei Lü, Tiejun Chun, Xiaoqing Xu, Zhiming Yan, Xuchao Wang, Sheng Xue, and Wei Lü, Thermodynamics and kinetics of alumina and magnesium oxide in calcium ferrite sintering process, Int. J. Miner. Metall. Mater., 32(2025), No. 7, pp.1538-1550. https://doi.org/10.1007/s12613-024-3070-x
Rende Chang, Chengyi Ding, Hongming Long, Xuewei Lü, Tiejun Chun, Xiaoqing Xu, Zhiming Yan, Xuchao Wang, Sheng Xue, and Wei Lü, Thermodynamics and kinetics of alumina and magnesium oxide in calcium ferrite sintering process, Int. J. Miner. Metall. Mater., 32(2025), No. 7, pp.1538-1550. https://doi.org/10.1007/s12613-024-3070-x
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Al2O3和MgO对烧结过程铁酸钙结晶行为热力学和动力学分析

摘要: 在烧结矿中,Al2O3和MgO是主要的脉石成分,对于CaO–Fe2O3xAl2O3(wt%,C–F–xA)和CaO–Fe2O3xMgO(wt%,C–F–xM)体系的形成至关重要。本研究使用差示扫描量热法研究了C–F–xA和C–F–xM体系的非等温结晶热力学行为,并通过X射线衍射和扫描电子显微镜对不同C–F–xA和C–F–xM体系的相组成和微观结构进行分析。结果表明,在C–F–2A和C–F–2M体系中,冷却速率的增加促进了CaFe2O4(CF)的析出,抑制了Ca2Fe2O5(C2F)的形成。在C–F–xA体系中,C–F–2A体系的理论初晶相析出温度(1566 K)低于C–F体系(1578 K),在C–F–4A和C–F–8A体系中,初晶相析出温度分别降低到1554 K和1528 K。在C–F–xM体系中,MgO含量的增加提高了结晶温度。同时,主要由Fe3O4和MgFe2O4组成的尖晶石相(MF相)和C2F相的增强析出抑制CF析出反应。在动力学计算方面,Ozawa法揭示了C–F–2A和C–F–2M体系的表观活化能。Malek法表明,C–F–2A体系最初遵循对数定律(ln α 或 ln α2),后来转变为反应级数函数((1−α)−1 或 (1−α)−1/2n = 2/3)或指数形式的 ln α2函数。C–F–2M系统始终遵循序列 ƒ(α) = (1−α)2。(α表示结晶转化率;n 是Avrami常数;ƒ(α)是C2F和CF结晶过程的模型函数微分方程。)

 

Thermodynamics and kinetics of alumina and magnesium oxide in calcium ferrite sintering process

Abstract: Al2O3 and MgO serve as the primary gangue components in sintered ores, and they are critical for the formation of CaO–Fe2O3xAl2O3 (wt%, C–F–xA) and CaO–Fe2O3xMgO (wt%, C–F–xM) systems, respectively. In this study, a nonisothermal crystallization thermodynamics behavior of C–F–xA and C–F–xM systems was examined using differential scanning calorimetry, and a phase identification and microstructure analysis for C–F–xA and C–F–xM systems were carried out by X-ray diffraction and scanning electron microscopy. Results showed that in C–F–2A and C–F–2M systems, the increased cooling rates promoted the precipitation of CaFe2O4 (CF) but inhibited the formation of Ca2Fe2O5 (C2F). In addition, C–F–2A system exhibited a lower theoretical initial crystallization temperature (1566 K) compared to the C–F system (1578 K). This temperature further decreases to 1554 K and 1528 K in the C–F–4A and C–F–8A systems, respectively. However, in C–F–xM system, the increased MgO content raised the crystallization temperature. This is because that the enhanced precipitation of MF (a spinel phase mainly comprised Fe3O4 and MgFe2O4) and C2F phases suppressed the CF precipitation reaction. In kinetic calculations, the Ozawa method revealed the apparent activation energies of the C–F–2A and C–F–2M systems. Malek’s method revealed that the crystallization process in C–F–2A system initially followed a logarithmic law ( \mathrmln\ \alpha or \mathrmln\ \alpha^2 ), later transitioning to a reaction order law ((1−α)−1 or (1−α)−1/2, n = 2/3) or the \mathrmln\ \alpha^2 function of the exponential law. In C–F–2M system, it consistently followed the sequence ƒ(α) = (1−α)2 (α is the crystallization conversion rate; n is the Avrami constant; ƒ(α) is the differential equations for the model function of C2F and CF crystallization processes).

 

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