The evolution of coal, examining the transitions from anthracite to natural graphite: a spectroscopy and optical microscopy evaluation  

作　　者：Liang YUAN Qinfu LIU Kuo LI Ying QUAN Xiaoguang LI Jonathan P.MATHEWS 

机构地区：[1]School of Geosciences and Surveying Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China [2]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [3]The EMS Energy Institute,and the Leone Family Department of Energy and Mineral Engineering,Pennsylvania State University,University Park PA 16802,USA

出　　处：《Frontiers of Earth Science》2023年第1期87-99,共13页地球科学前沿（英文版）

基　　金：This work is supported by the National Natural Science Foundation of China(Grant Nos.41672150 and 42002187);the Scholarship from the China Scholarship Council(No.201906430017).

摘　　要：Coal-derived natural graphite(CDNG)has multiple industrial applications.Here,ten metamorphic coals from anthracite to CDNG were obtained from Lutang and Xinhua in the Hunan Province and Panshi in the Jilin Province.Bulk characterization(proximate and ultimate analyses,X-Ray powder diffraction(XRD),and powder Raman spectroscopy),along with optical microscopy,scanning electron microscope(SEM)and micro-Raman spectroscopy were utilized to examine the transitions from anthracite to semi-graphite to CDNG.The XRD and Raman spectroscopy data indicate that from anthracite to highly ordered graphite the average crystal diameter(La)and height(Lc)increased from 6.1 and 4.6 nm to 34.8 and 27.5 nm,respectively.The crystalline parameters of the CDNG samples from Panshi and Lutang varied slightly when closer to the intrusive body.Optical microscopy and SEM indicated that in the anthracite samples there were thermoplastic vitrinite,devolatilized vitrinite,and some“normal”macerals.In the meta-anthracite,pyrolytic carbon,mosaic structure,and crystalline tar were present.In the CDNG there were flake graphite,crystalline aggregates,and matrix graphite.The crystalline aggregates show the highest structural ordering degree as determined from Raman spectral parameters(full-width at half maxima(G-FWHM)~20 cm^(−1),D1/(D1+D2+G)area ratio(R2)value<0.5).The flake graphite is less ordered with G-FWHM~28 cm^(−1) and 0.5<R2<1,but a larger grain size(up to 50μm).The mosaic structures were likely the precursors of the matrix graphite through in situ solid-state transformation.The pyrolytic carbon and crystalline tars are the transient phase of gas-state and liquid-state transformations.This study is beneficial to realize the rational utilization of CDNG.

关 键 词：micro-Raman spectroscopy structural ordering evolution coal-derived natural graphite XRD ANTHRACITE 

分 类 号：P618.13[天文地球—矿床学]