高灰煤中矿物质及碳结构的振动光谱分析

利用傅里叶变换红外光谱(FT-IR)、拉曼光谱和X射线衍射(XRD),分析了广西合山煤(GX)和平顶山煤(PD)及其酸洗煤的矿物质组分和碳结构。FT-IR谱图显示,GX和PD原煤的高岭石含量最为丰富,其次是石英和方解石,由二阶导数红外谱图发现,煤中还存在云母、蛇纹石、石膏和碱性长石。此外,从FT-IR谱图出现的三个层间水OH伸缩振动峰(3 695、3 651和3 619 cm^-1)判断煤中高岭石的结晶度不高。酸洗煤的FT-IR和XRD分别显示出清晰的芳香C=C官能团峰(1 600 cm^-1)和微晶碳(002)衍射峰;原煤的FT-IR和XRD都表明,矿物质完全掩盖了碳的信息。尽管如此,原煤及酸洗煤的拉曼谱图显示出清晰的缺陷碳峰(D峰)和石墨碳峰(G峰),而矿物质的信息完全被信号更强的碳峰掩盖。酸洗处理对煤的碳结构有较弱的影响,酸洗煤的碳结构有序度略低于原煤。

Characterization of mineral matters and carbonaceous structure of high-ash coals by vibrational spectroscopy

Mineral matters and carbonaceous structure of both raw and acid-washed Guangxi Heshan (GX) and Pingdingshan (PD) coals were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Raman spectroscopy and X-ray diffraction (XRD). The FT-IR spectra demonstrate that the two raw coals are most abundant in kaolinite, followed by quartz and calcite. Some new mineral matters such as muscovite, serpentine, gypsum and alkali-feldspar are clearly observed from the second derivative FT-IR spectra. In addition, three OH stretching vibration peaks are shown in the FT-IR spectra at 3 695, 3 651 and 3 619 cm^-1, indicating that the kaolinite in coals is not well crystallized. For demineralized coals, aromatic C=C peak (1 600 cm^-1) and (002) diffraction peak of microcrystalline carbon are obviously shown in FT-IR and XRD spectra, respectively. In the case of raw coals, both FT-IR and XRD spectra show that the carbonaceous structure is almost completely inhibited by mineral matters. However, the defect carbon (D peak) and graphite carbon (G peak) are clearly found in the Raman spectra for both raw and acid-washed coals, since the mineral matters are completely inhibited by carbon due to more intensive signal. The crystalline carbon is found to be slightly less ordered for demineralized coals than for raw coals, and therefore the carbonaceous structure is slightly affected by acid treatment.