特厚煤层分组间隔放煤顶煤运移规律研究

Study of top-coal flow mechanism under interval and multi-grouping top-coal caving technology in extra thick coal seam

综采放顶煤采煤法已成为我国特厚煤层主流的高产高效开采方法,但当前仍面临煤炭采出率低、含矸率较高的问题。塔山矿8222工作面顶煤平均厚度12 m,采用放顶煤开采,生产过程中尝试采用“大中小微”分组间隔放煤方式。为研究该放煤方式的原理及提高其放煤效率,并为开发智能放煤控制程序提供依据,采用CDEM颗粒离散元软件模拟分析了塔山矿开采条件下间隔放煤分组方法、顶煤运移规律、煤岩分界面特征以及顶煤放出率等,在此基础上揭示了组内支架数量对顶煤放出体形态的影响机制。数值模拟结果表明,顶煤厚度为12 m及见矸关门条件下,组内支架数量为9架是最优的分组间隔放煤方式;工业性试验表明,组内支架为9架的分组间隔“大中小微”放煤方式条件下的顶煤放出率为80.53%,含矸率4.00%,煤炭采出率高达85.31%。此外,组内支架数量对放煤漏斗形态影响较大;组内支架较少时,第1级放煤过程中相邻放煤口之间影响较大,中间形成畸形顶煤形态的可能性较大,在下一级放煤时容易出现混矸,导致架间残留煤量增加。分组间隔放煤的最佳支架间隔数量与煤厚密切相关;对于特厚煤层,合理增加间隔数可有效减少架间顶煤的遗留量,提高顶煤放出率。研究结果可为特厚煤层综放开采放煤工艺和参数合理确定提供参考。

Fully-mechanized top-coal caving mining method has become the main high-yielding and high-efficiency mining method in China’s extra-thick coal seam,but it still faces the problems of low coal production rate and high mixed gangue ratio.The longwall work⁃ing face No.8222 of Tashan Coal Mine with a coal seam average thickness of 12 m,adopts a novel"large-middle-small-micro"interval top-coal caving method.In order to study the mechanism of the caving method and improve the caving efficiency,and to provide the basis for the development of intelligent caving control program,this study performed CDEM software and theoretical analysis method to investigate the grouping approach,the corresponding top-coal movement law,the characteristics of coal rock interface and the top-coal ca⁃ving rate,and finally revealed the effect of the number of caving openings on the caving body shape.The numerical simulation results show that under the condition of top-coal thickness being 12 m and the principle of"gangue appears,caving opening closes",the number of ca⁃ving openings in the group is 9.The field test also confirms that the optimal caving opening number is 9 in a group,of which the top-coal recovery rate,mixed gangue rate and coal recovery rate are 80.53%,4.00%and 85.31%,respectively.In addition,the number of hydraulic supports in the group has a great influence on the shape of top-coal caving body.When the number of hydraulic supports in a group is small,the influence between adjacent caving hoppers in the first stage of top-coal caving is greater,and the possibility of forming abnormal top-coal in their middle is greater.In the next stage of top-coal caving,mixed gangue is easy to occur,resulting in the increase of residual coal between the adjacent caving openings.The optimal group spacing is proportional to the coal seamthickness.For the extra-thick coal seam,reasonable increase of the group spacing can effectively reduce the amount of top coal left between hydraulic supports and improve the top-coal recovery rate.Research results is of significance to provide a reference for the reasonable determination of the technology and parameters of the fully-mechanized top-coal caving in the extra thick coal seam.