Mechanism and Application of Hydraulic Fracturing in the High-Level Thick and Hard Gangue Layer to Improve Top Coal Caving in Fully Mechanized Caving Mining of an Ultra-Thick Coal Seam

Hongye Luo; Shun Liang; Qiangling Yao; Yisong Hao; Xuehua Li; Furong Wang; Xiaoyu Chen; Miao Yang

doi:10.3390/min12121605

Minerals (Dec 2022)

Mechanism and Application of Hydraulic Fracturing in the High-Level Thick and Hard Gangue Layer to Improve Top Coal Caving in Fully Mechanized Caving Mining of an Ultra-Thick Coal Seam

Hongye Luo,
Shun Liang,
Qiangling Yao,
Yisong Hao,
Xuehua Li,
Furong Wang,
Xiaoyu Chen,
Miao Yang

Affiliations

Hongye Luo: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Shun Liang: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Qiangling Yao: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Yisong Hao: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Xuehua Li: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Furong Wang: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Xiaoyu Chen: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China
Miao Yang: Key Laboratory of Deep Coal Resource Mining, Ministry of Education, School of Mines, China University of Mining and Technology, Xuzhou 221008, China

DOI: https://doi.org/10.3390/min12121605
Journal volume & issue: Vol. 12, no. 12
p. 1605

Abstract

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The thick and hard gangue layer has long been one of the key obstacles affecting the coal recovery rate in the fully mechanized top-coal caving mining of ultra-thick coal seams, and it is also one key factor restricting the development of the technology used for such work. In this study, to improve the poor top coal cavability and low recovery rate in fully mechanized caving mining of ultra-thick coal seams containing thick and hard gangue layers, the fully mechanized caving mining of longwall working face 42,108 of the Qinggangping Coal Mine is the engineering setting. Then, through a combination of theoretical analysis, numerical simulation, and field practice, a mechanical model of the cantilever beam with uniform load for fracture of the gangue layer is developed. Next, the mechanical action mechanism and influence of the gangue layer and thickness on the fracture of the cantilever beam are analyzed, and a method of pre-fracturing and weakening high-level thick and hard gangue layers using hydraulic fracturing technology is proposed. Finally, using RFPA2D-flow numerical simulation, the key technical parameters of hydraulic fracturing in the working face are designed and applied to field practice. The results show the following: After the high-level thick and hard gangue layer is treated by hydraulic fracturing technology, the amount of fractured gangue behind the support increases, while that of big coal blocks decreases significantly, and the overall fragmentation of top coal is at a reasonable level. In addition, after taking hydraulic fracturing technical measures during the mining period of the working face, the average recovery rate of the working face is 86.6%. This is an increase of 6.5% over the previous area without hydraulic fracturing.

Published in Minerals

ISSN: 2075-163X (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Geology: Mineralogy
Website: https://www.mdpi.com/journal/minerals

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