Coal is often coated by kaolinite in flotation, leading to a decrease in the quality of clean coal. The structure of the mineral determines its properties and flotation behavior. Therefore, to remove the kaolinite from coal efficiently, the difference in mineralogical characteristics between non-coal and coal kaolinite were analyzed using advanced instruments. The experiment results showed that, due to the substitution of the C atom for Si atom, the interplanar spacing of the kaolinite (001) surface became small with C-O-C, Al-O-C, and C-O-Si covalent bonds formed instead of Al-O-Si and Si-O-Si bond. Based on this, the models of monolayer and bilayer coal kaolinite (001) surfaces were built and the structure difference was compared through DFT calculation. The calculation results showed that the silicon atom of the kaolinite Si-O-(001) surface was easier to be doped by carbon atoms with external energy as the interplanar spacing of the kaolinite (001) surface decreased with the increase in doped carbon atoms (7.15440 A→7.11859 A→7.10902 A→7.10105 A). The structural difference between non-coal kaolinite and coal kaolinite were compared from the view of the experiment and quantum chemistry, which provides an important theory for subsequent research on the properties of coal kaolinite and its further processing and utilization.

中文翻译：

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煤高岭石和非煤高岭石晶体结构的研究：实验和 DFT 模拟的见解

煤在浮选过程中常被高岭石包覆，导致精煤质量下降。矿物的结构决定了其性质和浮选行为。因此，为了有效去除煤中的高岭石，利用先进的仪器分析了非煤和煤高岭石在矿物学特征上的差异。实验结果表明，由于C原子取代了Si原子，高岭石（001）表面的晶面间距变小，形成了COC、Al-OC和CO-Si共价键而不是Al-O- Si 和 Si-O-Si 键。在此基础上建立了单层和双层煤高岭石（001）表面模型，并通过DFT计算比较了结构差异。计算结果表明，随着掺杂碳原子的增加，高岭石（001）表面的晶面间距减小，高岭石Si-O-（001）表面的硅原子更容易被具有外部能量的碳原子掺杂（ 7.15440 A→7.11859 A→7.10902 A→7.10105 A)。从实验和量子化学的角度比较了非煤高岭石和煤高岭石的结构差异，为后续煤高岭石的性质研究及其进一步加工利用提供了重要理论依据。