Characterization of coal using electron spin resonance： implications for the formation of inertinite macerals in the Witbank Coalfield, South Africa  

作　　者：Ofentse M. Moroeng Jonathan M. Keartland R. James Roberts Nicola J. Wagner 

机构地区：[1]Department of Geology, University of Johannesburg,P.O. Box 524, Auckland Park 2006, South Africa [2]Department of Geology, University of Pretoria, Mineral Sciences Building, Pretoria 0002, South Africa [3]School of Physics and Materials Physics Institute, University of the Witwatersrand, Johannesburg 2050, South Africa

出　　处：《International Journal of Coal Science & Technology》2018年第3期385-398,共14页国际煤炭科学技术学报（英文）

摘　　要：Coal contains a significant concentration of free radicals as a result of the coalification process. One of the experimental methods sensitive to the presence of radicals is electron spin resonance （ESR）, and differences in ESR spectra for different macerals may provide insight into coal-forming processes. In this study, ESR data along with the H/C atomic ratio （to infer the aromatic fraction） are used to characterize coal samples with the aim of assessing a fire-origin for dominant inertinite macerals. A medium rank C bituminous Witbank No. 4 Seam Upper coal （the parent） was density- fractionated to create vitrinite-rich and inertinite-rich samples. The parent sample consists of 42 vol% vitrinite and 49 vol% inertinite. The density-fractionated samples comprise of 81 vol% total vitrinite （dominated by collotelinite and collodetrinite）, and 63 vol% total inertinite （dominated by fusinite, semifusinite, and inertodetrinite）. The H/C ratio is 0.74 for the inertinite-rich sample, and 0.85 for the vitrinite-rich counterpart, suggesting the former sample is more aromatic. The ESR spectra obtained for the three samples were found to fit best using a Lorentzian distribution. The fit is noticeably better for the aromatic inertinite-rich sample, for which the spectrum is symmetric. This is attributed to pronounced electron mobility and exchange interactions. The higher radical content of the inertinite-rich and parent samples is attributed to the presence of specific inertinite macerals, namely： fusinite, semifusinite, and inertodetrinite. And, owing to the greater radical content of the inertinite-rich sample, the dominant inertinite macerals are interpreted to have formed through charring of plant matter.

关 键 词：Main Karoo Basin Radical contents Origin pathways CHARRING Fusinite Semifusinite 

分 类 号：O562.5[理学—原子与分子物理] P618.110.2[理学—物理]