Top Coal Movement Law of Dynamic Group Caving Method in LTCC with an Inclined Seam
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Top Coal Movement Law of Dynamic Group Caving Method in LTCC with an Inclined Seam Shengli Yang 1,2 & Weijie Wei 1,2
&
Jinwang Zhang 1,2
Received: 20 November 2019 / Accepted: 29 June 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract Due to the unbalanced top coal drawing process, the recovery ratio is low, and the equipment stability is poor in the longwall top coal caving mining (LTCC) with an inclined seam. Aimed at these problems, this paper proposes the dynamic group caving method (DGCM). The basic procedure is that when the drawn volume of top coal from a support reaches about half, the next support begins drawing top coal, and the drawing process between the two supports is half done. Taking the panel no. 8103 in Beixinyao mine as the research object, the characteristics of drawing body shape, particle movement trace, and variation of recovery ratio are investigated by using Particle Flow Code. Furthermore, the effect of mining-caving ratio on the top coal drawing law under DGCM is revealed by the simulation results, and compared with the single-opening sequence caving method (SSCM) and the doubleopenings sequence caving method, advantages of DGCM are determined in inclined seams. The results show that the drawing body can be divided into the left and the right under DGCM. Specifically, the drawn top coal particles in the left are from the upper part of this support, that in the right are from the lower part of next support, which verifies the correctness of the theoretical analysis. The characteristics of the drawing body shape are more significant when the mining-caving ratio is relatively small. In addition, with increasing mining-caving ratio, the recovery ratio of the panel both increases gradually under DGCM and SSCM. When the miningcaving ratio is less than 1:1, the recovery ratio of DGCM is obviously higher than that of SSCM, indicating that DGCM can greatly improve the recovery ratio. While when the mining-caving ratio is larger than 1:1, the recovery ratio of two caving methods is basically equal; however, the advancing time is significantly shortened under DGCM. This study are of great significance to realize high efficiency and precise caving in LTCC with an inclined seam. Keywords Longwall top coal caving mining . Dynamic group caving method . Drawing body . Recovery ratio . Particle movement trace
1 Introduction Longwall top coal caving mining (LTCC) is an efficient mining method to extract thick and extra-thick seams. As shown in Fig. 1, the bottom coal is extracted by the shearer and transported out of the panel by the front armored face conveyor (AFC), while the loose top coal that fractured by the mining stress and repeated force of support is drawn from the support opening (SO) and transferred out of the panel by the rear AFC.
* Weijie Wei [email protected] 1
School of Energy and Mining Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China
2
Coal Industry Engineering Research Center of Top-coal Caving Mining, Beijing 100083
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