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| Microstructural characteristics of low-rank coal from Hunchun based on SEM |
| ZOU Junpeng1，CHEN Weizhong1，2，YANG Diansen1，YU Hongdan1，TAN Xianjun1 |
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of
Sciences，Wuhan，Hubei 430071，China；2. Geotechnical and Structural Engineering Research Center，
Shandong University，Jinan，Shandong 250061，China) |
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Abstract Currently，the mineral component and anisotropic microstructure of the low-rank coal are lack of systematically quantitative research. The scanning electron microscope(SEM) test and mercury test were carried out to analyze the anisotropic characteristics of the morphology and distribution of microcracks. The microscopic images were processed into the binary digital images of minerals and micro-cracks with the appropriate gray threshold. The mineral percentage in coal，the volumetric percentage of microcracks in parallel directions and perpendicular directions of the beddings were calculated. The box fractal dimension of micro-cracks that parallel to and perpendicular to bedding seam scanned by SEM were calculated based on the fractal theory，according to which the micro cracks perpendicular to bedding microstructure is relatively smooth and irregular. According to the mercury test to coal samples，the total volume of injected mercury changes with pressure，the apertures of coal samples were mostly distributed in 10–100 nm or 15–95 ?m，and the largest specific surface area for microcrack is around 10–100 nm. The pore distribution of coal explant lamellar structure and mineral floc structure by SEM also around 10–100 nm. It indicates that the explant lamellar structure and minerals flocculent structure of coal could provide a larger specific surface area and the coal explant could have very strong adsorption capacity of coal bed methane(CBM).
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2016, Vol. 35 
