As one of the elements having significant affinity for organic matter in low-rank coals, aluminum (Al) can form strong complexes with organic matter. Measurable concentration of Al has been detected in ‘clean’ macerals of coal, especially vitrinite. This raises interesting questions on the modes of occurrence of Al in coal and the specific way of Al associated with organic matter. In this study, the mineral characteristics, content of major-element oxides, and modes of occurrence of Al in Carboniferous-Permian coals from the Hedong Coalfield are investigated. Our study shows that Al in coal occurs primarily as aluminosilicate minerals such as kaolinite and illite. This is supported by the strong correlation between Al₂O₃ and SiO₂ concentrations and the bulk of Al being removed by HF during sequential leaching. The proportion of Al bound by maceral as a non-mineral element (NME) is low (< 6%), as suggested by the mass ratio of Al₂O₃ in the demineralized vitrain band to that of in the bulk coal. This is in accord with the sequential leaching results, which shows that the proportion of Al in the HNO₃ leachate and the residue is less than 20%. Transmission electron microscopy (TEM) combined with fast Fourier transform (FFT) and energy-dispersive spectroscopy (EDS) have found that aluminosilicate minerals are the most ubiquitous nanoscale particles in the vitrain band. Nano-sized andalusite, pyrophyllite, donbassite, and kyanite, as well as some amorphous Al-bearing nanomaterials are identified. These results indicate that some of the Al, which is assumed as being in an organic association, may be truly associated with minerals. These Al-bearing nanoparticles and amorphous nanomaterials observed in the studied vitrain band may be of detrital origin, or from Al complexes concentrated in vitrinite.

铝（Al）是低阶煤中对有机物具有显着亲和力的元素之一，能与有机物形成强络合物。已在“清洁”煤质，尤其是镜质体中检测到可测量浓度的铝。这对煤中铝的赋存方式以及铝与有机质的具体结合方式提出了有趣的问题。本研究对河东煤田石炭—二叠系煤中铝的矿物特征、主要元素氧化物含量及铝的赋存方式进行了研究。我们的研究表明，煤中的铝主要以铝硅酸盐矿物形式存在，例如高岭石和伊利石。这得到了 Al ₂ O ₃和 SiO ₂之间强相关性的支持浓度和大量铝在连续浸出过程中被 HF 去除。正如脱矿玻璃钢带中的 Al ₂ O ₃与散装煤中的 Al ₂ O ₃的质量比所表明的那样，作为非矿物元素 (NME) 被微晶结合的 Al 的比例很低 (< 6%) 。这与序贯浸出结果一致，表明 HNO ₃中 Al 的比例渗滤液，残渣小于20%。透射电子显微镜 (TEM) 结合快速傅里叶变换 (FFT) 和能量色散光谱 (EDS) 发现，铝硅酸盐矿物是玻璃管带中最普遍的纳米级颗粒。纳米尺寸的红柱石、叶蜡石、铜柱石和蓝晶石，以及一些无定形含铝纳米材料被鉴定出来。这些结果表明，一些被假定为有机组合的铝可能确实与矿物有关。在所研究的玻璃体带中观察到的这些含铝纳米粒子和无定形纳米材料可能来自碎屑，或者来自浓缩在玻璃体中的铝复合物。