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Xinran Zhu, Yuangan Chen, Xu Liu, Yongsheng Sun, and Yuexin Han, Microwave fluidization magnetization roasting of limonite ores: Phase transformation, microstructure and kinetics, Int. J. Miner. Metall. Mater., 32(2025), No. 7, pp.1519-1528. https://doi.org/10.1007/s12613-024-3018-1
Xinran Zhu, Yuangan Chen, Xu Liu, Yongsheng Sun, and Yuexin Han, Microwave fluidization magnetization roasting of limonite ores: Phase transformation, microstructure and kinetics, Int. J. Miner. Metall. Mater., 32(2025), No. 7, pp.1519-1528. https://doi.org/10.1007/s12613-024-3018-1
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褐铁矿微波流态化焙烧:矿相转化、微观结构及动力学

摘要: 褐铁矿作为一种典型难选铁矿石,其清洁高效分离对于维持战略性金属铁的长期稳定供应至关重要。本研究提出了一种基于微波流态化技术的磁化焙烧新工艺。利用扫描电子显微镜、全自动比表面积及孔隙度分析仪、X射线衍射仪和振动样品磁强计对焙烧产物的微观形貌、微观结构、矿相组成进行了系统表征,并开展了等温动力学研究。实验结果表明微波流态化焙烧增大了褐铁矿的比表面积,显著增强了CO的扩散效率,加速褐铁矿从FeO(OH)到α-Fe2O3,再到Fe3O4的转变过程。矿物结构水和重构磁铁矿的协同微波吸收效应强化了褐铁矿的还原焙烧。优化焙烧条件后,褐铁矿焙烧产物的饱和磁化强度和最大比磁化系数分别可达23.08 A·m2·kg−1和2.50 × 10−4 m3·kg−1。在原矿铁品位为32.89wt%的条件下,经焙烧–磁选工艺处理获得了铁品位为59.26wt%,回收率为90.07wt%的铁精矿。动力学分析表明,该反应遵循扩散控制机理(D1模型),其机理函数可描述为k = 0.08208exp(−20.3441/(RgT))。本研究证实,微波流态化焙烧技术通过耦合微波场强化与流态化传质优势,实现了褐铁矿资源的高效清洁利用,为难选铁矿石的开发提供了一种具有广阔前景的技术方案。

 

Microwave fluidization magnetization roasting of limonite ores: Phase transformation, microstructure and kinetics

Abstract: As a refractory iron ore, the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal. In this study, the microwave fluidization magnetization roasting of limonite was explored. The micromorphology, microstructure, and mineral phase transformation of the roasted products were analyzed using a scanning electron microscope, an automatic surface area and porosity analyzer, an X-ray diffractometer, and a vibrating sample magnetometer. Kinetic analysis was also conducted to identify the factors limiting the roasting reaction rate. Microwave fluidization roasting significantly increased the specific surface area of limonite, increased the opportunity of contact between CO and limonite, and accelerated the transformation from FeO(OH) to α-Fe2O3 and then to Fe3O4. In addition, the water in the limonite ore and the newly formed magnetite exhibited a strong microwave absorption capacity, which has a certain activation effect on the reduction roasting of limonite. The saturation magnetization and maximum specific magnetization coefficient increased to 23.08 A·m2·kg−1 and 2.50 × 10−4 m3·kg−1, respectively. The subsequent magnetic separation of the reconstructed limonite yielded an iron concentrate with an Fe grade of 59.26wt% and a recovery of 90.07wt%. Kinetic analysis revealed that the reaction mechanism function model was consistent with the diffusion model (G(α) = α2), with the mechanism function described as k = 0.08208exp−20.3441/(RgT). Therefore, microwave fluidization roasting shows significant potential in the beneficiation of limonite, offering a promising approach for the exploitation of refractory iron ores.

 

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