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Yufeng Guo, Jinlai Zhang, Shuai Wang, Jianjun Fan, Haokun Li, Feng Chen, Kuo Liu, and Lingzhi Yang, Diffusion and reaction mechanism of limestone and quartz in fluxed iron ore pellet roasting process, Int. J. Miner. Metall. Mater., 31(2024), No. 3, pp.485-497. https://dx.doi.org/10.1007/s12613-023-2739-x
Yufeng Guo, Jinlai Zhang, Shuai Wang, Jianjun Fan, Haokun Li, Feng Chen, Kuo Liu, and Lingzhi Yang, Diffusion and reaction mechanism of limestone and quartz in fluxed iron ore pellet roasting process, Int. J. Miner. Metall. Mater., 31(2024), No. 3, pp.485-497. https://dx.doi.org/10.1007/s12613-023-2739-x
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熔剂性球团焙烧过程中石灰石和石英的扩散反应机制研究

摘要: 提高熔剂性球团在高炉炉料中的比例是降低炼铁过程中碳排放的有效途径。本文通过设计扩散偶试验,研究了焙烧过程中石灰石和石英与铁矿粉之间的相互作用以及熔剂性铁矿球团矿化机理。利用扫描电子显微镜和能谱技术研究了焙烧过程中元素的扩散和相变过程。研究结果表明,在预热过程前期石灰石迅速分解为氧化钙,磁铁矿被氧化成赤铁矿。随着焙烧温度的升高,Fe和Ca的扩散速度明显加快,而Si的扩散速度相对缓慢。经1200°C焙烧9 h时,Fe2O3–CaO系扩散偶的互扩散系数数量级为10−10 m2·s−1。Fe2O3–CaO–SiO2扩散界面的初始产物为Ca2Fe2O5,随后Ca2Fe2O5继续与Fe2O3反应生成CaFe2O4。随着扩散区域的扩大,石英固溶进CaFe2O4产生复合铁酸钙液相,从而提高了熔剂性球团的固结强度。同时,少量石英颗粒周围还会形成有利于熔剂性球团固结的钙铁榴石相。此外,还形成了熔剂性球团焙烧过程石灰石和石英扩散反应的机理模型。

 

Diffusion and reaction mechanism of limestone and quartz in fluxed iron ore pellet roasting process

Abstract: The increase to the proportion of fluxed pellets in the blast furnace burden is a useful way to reduce the carbon emissions in the ironmaking process. In this study, the interaction between calcium carbonate and iron ore powder and the mineralization mechanism of fluxed iron ore pellet in the roasting process were investigated through diffusion couple experiments. Scanning electron microscopy with energy dispersive spectroscopy was used to study the elements’ diffusion and phase transformation during the roasting process. The results indicated that limestone decomposed into calcium oxide, and magnetite was oxidized to hematite at the early stage of preheating. With the increase in roasting temperature, the diffusion rate of Fe and Ca was obviously accelerated, while the diffusion rate of Si was relatively slow. The order of magnitude of interdiffusion coefficient of Fe2O3–CaO diffusion couple was 10−10 m2·s−1 at a roasting temperature of 1200°C for 9 h. Ca2Fe2O5 was the initial product in the Fe2O3–CaO–SiO2 diffusion interface, and then Ca2Fe2O5 continued to react with Fe2O3 to form CaFe2O4. With the expansion of the diffusion region, the sillico-ferrite of calcium liquid phase was produced due to the melting of SiO2 into CaFe2O4, which can strengthen the consolidation of fluxed pellets. Furthermore, andradite would be formed around a small part of quartz particles, which is also conducive to the consolidation of fluxed pellets. In addition, the principle diagram of limestone and quartz diffusion reaction in the process of fluxed pellet roasting was discussed.

 

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