煤系石墨显微组分与结构特征  

Characteristics of microscopically distinguishable components and structures of the coaly graphite

作　　者：李阔[1] 刘钦甫[1] 张帅[1] 袁亮 LI Kuo;LIU Qin-Fu;ZHANG Shuai;YUAN Liang(College of Geoscience and Surveying Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)地球科学与测绘工程学院,北京100083〉

出　　处：《矿物学报》2021年第1期101-108,共8页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:41672150;42002187;41802189);中国博士后科学基金项目(2020M680755)。

摘　　要：煤系石墨是岩浆侵入含煤地层导致煤层受热变质形成,是一种重要的非金属矿产资源。本文通过对湖南娄底和郴州地区典型煤系石墨进行煤岩学、X射线衍射(XRD)、激光显微拉曼光谱(Raman)和扫描电子显微镜(SEM)分析,并与无烟煤、美国伊利诺伊盆地的天然煤焦、美国科罗拉多中南部Trinidad煤田的天然沥青焦、斯里兰卡的显晶质石墨进行对比研究。结果表明,煤系石墨显微组分主要为隐晶质石墨(体积含量>80%),还含有少量热解碳、针状石墨和鳞片石墨,偶见残余镜质组和惰质组,石墨单晶体尺寸约为0.35μm。反光显微镜下隐晶质石墨表面呈麻点状,由于石墨微小晶片对光的散射作用导致所测反射率值偏低(3%~5%);煤系石墨XRD图谱(002)峰为尖锐峰与无烟煤和天然焦的"鼓包"峰具有明显区别,(002)峰半高宽可作为区分煤系石墨、无烟煤及天然焦的主要参数;煤系隐晶质石墨一阶拉曼光谱有尖锐的G峰和低强度的D峰,二阶拉曼光谱出现2450cm-1峰和较强的2D峰,表明其结构演化处于石墨化作用过程,而无烟煤、变质无烟煤和天然焦则无2450cm-1峰,且2D峰较弱,表明其结构演化处于碳化作用过程。Coaly graphite is an important non-metallic mineral resource.It was transformed from coal by the metamorphism of the coal-bearing stratum which was intruded by the large scale magma.In this paper,the typical coaly graphite samples from the Loudi and Chenzhou areas of Hunan Province have been studied by using coal petrological methods,X-ray diffraction(XRD),micro-Raman spectroscopy,and scanning electron microscopy(SEM).A comparative study has also been undertaken among anthracite samples from the Loudi area of Hunan Province,coked coal from the Illinois basin,coked bitumen from the Colorado Trinidad coalfield,and crystalline graphite from Sri Lanka.It was found that cryptocrystalline graphite with microcrystal size of about 0.35μm is the main component of the coaly graphite(>80%by volume),with a small amount of pyrolytic carbon,needle graphite,and flake graphite,as well as occasionally residual vitrinite and inertinite.The rough surface of cryptocrystalline graphite observed under the reflecting light microscope could cause the scatter of incident light to result in the relatively low measured reflectance values of 3%-5%for the coaly graphite.The narrow(002)peak in the XRD spectrum of coaly graphite is obviously different to the broad banded peaks of anthracite and natural coke,so,full widths at half maximum(FWHM)height of(002)peaks in the XRD spectra of coaly graphite,anthracite and natural coke can be used as main parameters to distinguish coaly graphite from anthracite and coke.The sharp G band and a weak D band shown in the first order region and the relatively strong 2D band and an additional 2450 cm-1 peak shown in the second order region of the Raman spectra of coaly cryptocrystalline graphite suggest that its structural evolution occurred in the process of graphitization.However,there is weak 2D band and no 2450 cm-1 peak in the Raman spectra of anthracite,meta-anthracite,and natural coke,suggesting that their structural evolutions occurred in the process of carbonization.

关 键 词：煤系石墨 隐晶质石墨 光学特征 显微拉曼 显微组分 

分 类 号：P611[天文地球—矿床学]