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Energies 2017, 10(9), 1382; https://doi.org/10.3390/en10091382

Gas Permeability Evolution Mechanism and Comprehensive Gas Drainage Technology for Thin Coal Seam Mining

1
State Key Laboratory of Coal Resources and Mine Safety, School of Mines, Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, China University of Mining and Technology, Xuzhou 221116, China
2
State Key Laboratory of Coal Resources and Mine Safety, College of Resources & Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
3
Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology (Beijing), Beijing 100083, China
*
Author to whom correspondence should be addressed.
Received: 12 July 2017 / Revised: 22 August 2017 / Accepted: 8 September 2017 / Published: 12 September 2017
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Abstract

A thin coal seam mined as a protective coal seam above a gas outburst coal seam plays a central role in decreasing the degree of stress placed on a protected seam, thus increasing gas permeability levels and desorption capacities to dramatically eliminate gas outburst risk for the protected seam. However, when multiple layers of coal seams are present, stress-relieved gas from adjacent coal seams can cause a gas explosion. Thus, the post-drainage of gas from fractured and de-stressed strata should be applied. Comprehensive studies of gas permeability evolution mechanisms and gas seepage rules of protected seams close to protective seams that occur during protective seam mining must be carried out. Based on the case of the LongWall (LW) 23209 working face in the Hancheng coal mine, Shaanxi Province, this paper presents a seepage model developed through the FLAC3D software program (version 5.0, Itasca Consulting Group, Inc., Minneapolis, MI, USA) from which gas flow characteristics can be reflected by changes in rock mass permeability. A method involving theoretical analysis and numerical simulation was used to analyze stress relief and gas permeability evolution mechanisms present during broken rock mass compaction in a goaf. This process occurs over a reasonable amount of extraction time and in appropriate locations for comprehensive gas extraction technologies. In using this comprehensive gas drainage technological tool, the safe and efficient co-extraction of thin coal seams and gas resources can be realized, thus creating a favorable environment for the safe mining of coal and gas outburst seams. View Full-Text
Keywords: permeability evolution mechanism; protective seam mining; stress-relief; gas drainage technology; co-extraction of coal seam and gas resources permeability evolution mechanism; protective seam mining; stress-relief; gas drainage technology; co-extraction of coal seam and gas resources
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Wang, F.; Zhang, C.; Liang, N. Gas Permeability Evolution Mechanism and Comprehensive Gas Drainage Technology for Thin Coal Seam Mining. Energies 2017, 10, 1382.

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