Experimental and numerical investigation on coal drawing from thick steep seam with longwall top coal caving mining
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ORIGINAL PAPER
Experimental and numerical investigation on coal drawing from thick steep seam with longwall top coal caving mining Jin-wang Zhang 1,2
&
Jia-chen Wang 1,2 & Wei-jie Wei 1,2 & Yi Chen 1,2 & Zheng-yang Song 1,3
Received: 4 September 2017 / Accepted: 30 January 2018 # Saudi Society for Geosciences 2018
Abstract Steep coal seam mining activities will frequently occur during the next few decades in China. In this study, both experimental and numerical methods are employed to investigate the coal drawing from thick steep seam with longwall top coal caving mining. A series of analyses is performed to investigate the features of the drawing body, the distribution of top coal recovery ratio and the shape of the rock flow under steep conditions. The results indicate that the drawing body of top coal develops prior to upper side of the panel face obviously, and the top coal in the central part of the panel has a higher recovery ratio than that in the lower and upper parts in steep coal seam with caving mining method. The flow paths of the fragmented top coal are nearly straight lines moving towards the drawing window, and the fastest path maintains a constant angle with the plumb line. The spatial shape of the rock flow indicates Bbidirectional asymmetry,^ which results from the presence of the shield beam and dip angle of the coal seam; thus, this is the root cause of the appearance of the drawing body’s prior development towards the upper side of the panel. The field observation data indicates the same distribution of top coal recovery as that in the physical experiment and numerical simulation. Furthermore, suggested measurements are proposed to improve top coal recovery in steep seam mining based on the engineering practice of Dayuan coal mine. Keywords Longwall top coal caving (LTCC) . Steep coal seam . Fragmented coal and rock . Drawing body . Top coal recovery
Introduction China’s coal production accounts for approximately 48% of the world’s coal production, of which 85% comes from underground coal seam mining (Wang et al. 2015a, b). Steep coal seams (dip angle ≥ 45°) are widely distributed in China and around the world (Klishin and Klishin 2010; Zhang and Cao 2015; Kumar et al. 2016; Li et al. 2016). Near and far abroad deposits of thick steep coal are coal fields in Transcaucasia (Tvarkchelskoe and Shaorskoe deposits),
* Jin-wang Zhang [email protected] 1
College of Resources and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
2
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing 100083, China
3
Geotechnical Institute, TU Bergakademie Freiberg, Gustav-Zeuner-Straße 1, 09599 Freiberg, Germany
Central Asia (Shragunskoe deposit) as well as in Poland, Russia, Bulgaria, India (Klishin et al. 2013). In China, steep coal seams are primarily located in the central and western regions. Due to the exhaustion of the coal resources in eastern China, the focus of coal mining activities
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