Numerical Simulation Study on Technology Optimization of Large Section High Fully Mechanized Caving Mining in Vertical Coal Seam
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摘要:
乌东煤矿西采区近直立煤层采用水平分段综放开采。为提高生产效率，可通过适当提升水平分段高度代替延长较短的工作面，因此需对大段高条件下近直立煤层水平分段综放开采顶煤运移规律进行研究并优化放煤工艺参数以提高顶煤回收率。结合现场实测数据建立了各层位顶煤块度级配下的放煤模型，通过颗粒流离散元数值分析得出了大段高条件下初始放煤及周期放煤过程中顶煤运移规律，并对不同放煤参数及放煤顺序的顶煤回收量及煤损情况进行分析，提出了适用于乌东煤矿B3−6工作面的合理放煤工艺。结果表明：大段高条件下，周期放煤过程中煤矸分界线的底口处有向右侧偏转回勾的趋势，放出口提前见矸导致后续多步的放煤量较小，煤矸分界线严重滞后于放煤口，遗煤区域较大，可适当采用过量放煤缓解分界线回勾程度；采用6 m采高时，在周期放煤前期时放出体发育、顶煤流动性更好，产生的遗煤区相对较小；采用2.4 m放煤步距条件下每步放煤量更多且有助于缓解见矸过快问题；采用分段大间隔放煤方式分可以有效减小煤矸分界线的影响，遗煤范围最少，顶煤回收率达到93.23%。
Abstract:Wudong Coal Mine West Mining Area near vertical coal seam adopts horizontal section top−coal caving. In order to improve the production efficiency, the working face with short extension can be replaced by appropriately increasing the height of horizontal section. Therefore, it is necessary to study the top coal migration law of horizontal section top−coal caving in near vertical coal seam under the condition of large section height and optimize the coal caving technique to improve the top coal recovery rate. Combined with the field measured data, the model of coal drawing method under the condition of top coal size distribution of each layer is established. The top coal migration law in the process of initial coal drawing and periodic coal drawing under the condition of large section height are obtained by the Particle Flow Code numerical calculation. The top coal recovery and coal loss of each coal drawing parameter and order are analyzed, and the reasonable coal drawing technique suitable for B3−6 working face of Wudong Coal Mine is put forward. The results show that under the condition of large section height, the bottom of the coal−gangue boundary has a tendency to deflect to the right side during the periodic coal drawing process. The advance of the drawing opening position leads to a small amount of coal drawing in the subsequent multi−steps, and the coal−gangue boundary is seriously lagging behind the drawing opening position. The area of remnant coal is large. Therefore, excessive coal drawing can be appropriately used to alleviate the degree of demarcation of the boundary. When the mining height is 6 m, the development of coal drawing body and the fluidity of top coal are better in the early stage of periodic coal drawing, and the area of remnant coal is small. When the coal drawing interval is 2.4 m, the discharge amount of coal for each step is more and it is helpful to alleviate the problem of too fast seeing gangue. The coal drawing of “subsection drawing with large interval” can effectively reduce the influence of coal−gangue boundary line. The area of remnant coal is the smallest and the recovery of top coal reaches 93.23%.
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表 1 4#架放煤块度
Table 1. No. 4 hydraulic support coal drawing block degree
顶煤块度
范围/cm平均块度
/cm质量
/kg质量分数
/%累积质量
分数/%<10 5.0 7.69 13.83 13.83 10~15 12.5 5.41 9.73 23.56 15~20 17.5 4.17 7.50 31.06 20~25 22.5 1.47 2.64 33.70 25~30 27.5 4.84 8.71 42.41 30~35 32.5 14.62 26.30 68.71 35~40 37.5 17.40 31.29 100.00 总计 / 55.60 100.00 / 
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表 2 12#架放煤块度
Table 2. No. 12 hydraulic support coal drawing block degree
顶煤块度
范围/cm平均块度
/cm质量
/kg质量分数
/%累积质量
分数/%<10 5.0 8.92 12.63 12.63 10~15 12.5 2.97 4.21 16.84 15~20 17.5 3.17 4.49 21.33 20~30 25 2.89 4.09 25.42 30~40 32.5 9.90 14.02 39.44 40~50 37.5 21.00 29.75 69.19 50~55 52.5 21.80 30.81 100.00 总计 / 70.60 100.00 /
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表 3 24#架放煤块度
Table 3. No. 24 hydraulic support coal drawing block degree
顶煤块度
范围/cm平均块度
/cm质量
/kg质量分数
/%累积质量
分数/%<10 5.0 10.25 14.60 14.60 10~15 12.5 2.07 2.95 17.55 15~20 17.5 4.11 5.85 23.40 20~25 22.5 2.13 3.04 26.44 25~30 27.5 3.47 4.94 31.38 30~35 32.5 18.28 26.07 57.45 35~40 37.5 29.90 42.55 100.00 总计 / 70.21 100.00 /
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表 4 顶煤块度均值、标准差及变异系数
Table 4. Mean, standard deviation and coefficient of variation of top coal lumpiness
支架编号 块度均值/cm 标准差/cm 变异系数 4# 27.587 12.746 0.46 12# 39.238 17.320 0.44 24# 28.496 11.897 0.42 整体 31.774 13.988 0.44
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表 5 工作面整体顶煤块度占比
Table 5. Percentage of overall top coal lumps in the working face
顶煤块度范围/cm 质量/kg 质量分数/% 累积质量分数/% <10 26.86 13.68 13.68 10~15 10.45 5.32 19.00 15~20 11.45 5.83 24.83 20~25 3.60 1.83 26.66 25~30 11.15 5.68 32.34 30~35 23.67 12.05 44.39 35~40 49.03 24.96 69.35 40~50 17.40 8.86 78.21 50~55 42.80 21.79 100.00 总计 196.41 100.00 /
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表 6 模拟煤矸颗粒参数表
Table 6. Parameters of simulated gangue particles
岩层 法向刚度
kn/(N·m−1)切向刚度
ks/(N·m−1)密度
ρ/(kg·m−3)块度
/cm摩擦
系数下位煤层 2×108 2×108 1440 0~30 0.4 中位煤层 2×108 2×108 1440 40~55 0.4 上位煤层 2×108 2×108 1440 30~40 0.4 垮落矸石 4×108 4×108 2500 40~60 0.4
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表 7 模拟顶煤颗粒块度级配表
Table 7. Simulated top coal particle lumpiness grading table
顶煤块度范围/cm 各层位顶煤颗粒体积占比/% 下位顶煤 中位顶煤 上位顶煤 <10 42.29 / / 10~15 16.45 / / 15~20 18.03 / / 20~25 5.67 / / 25~30 17.56 / / 30~35 / / 32.56 35~40 / / 67.44 40~50 / 28.91 / 50~55 / 71.09 / 总计 100.00 100.00 100.00
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表 8 各采高损煤率
Table 8. Coal loss ratio of mining height
采高/m 放煤总量/m2 遗煤量/m2 损煤率/% 4 793.60 107.12 13.50 5 768.00 101.76 13.24 6 742.40 88.71 11.95
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表 9 各放出步距损煤率
Table 9. Coal loss rates by different coal drawing interval
步距/m 放煤总量/m2 遗煤量/m2 损煤率/% 1.6 742.40 88.71 11.95 2.4 779.52 93.31 11.97 3.2 742.40 98.98 13.44
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表 10 倾向模型颗粒参数
Table 10. Table of particle parameters for tendency models
岩层 法向刚度
kn/(N·m−1)切向刚度
ks/(N·m−1)密度
ρ/(kg·m−3)块度/cm 摩擦
系数顶煤 2×108 2×108 1440 见区间级配 0.4 顶板 4×108 4×108 2500 40~60 0.4 底板 4×108 4×108 2500 40~60 0.4 垮落矸石 4×108 4×108 2500 40~60 0.4
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表 11 各放煤方式的顶煤回收率
Table 11. Top coal recovery rates for different coal drawing methods
放煤方式 放出量/m2 回收率/% 顺序放煤 1027.82 85.54 端头逆序 1061.23 88.32 分段大间隔 1120.23 93.23
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