Motion Mechanisms for Top Coal and Gangue Blocks in Longwall Top Coal Caving (LTCC) with an Extra-Thick Seam
Motion Mechanisms for Top Coal and Gangue Blocks in Longwall Top Coal Caving (LTCC) with an Extra-Thick Seam
复制标题
特厚煤层长壁放顶煤放顶煤 (LTCC) 中顶煤和矸石块的运动机构
DOI：
10.1007/s00603-022-02928-2
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发表时间：
2022-06-04
影响因子：
6.2
通讯作者：
Wei Chuanbo
中科院分区：
文献类型：
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作者：
Wei Weijie;Yang Shengli;Wei Chuanbo
特厚煤层综放开采存在顶煤块体破碎大、放煤过程中易起拱、放煤均衡性差、顶煤回收率低等问题，严重影响了安全、高效、绿色开采。首次对特厚煤层低温共烧开采顶煤块体的粒度分布进行了测定。在实测结果的基础上，通过顶煤放出过程的离散元计算和物理实验，系统研究了特厚煤层顶煤与矸石块体的混合运动机理。结果表明，随着拉深高度的增加，拉深体的高宽比呈抛物线状增加，表明拉深体形状由短胖球逐渐变为高瘦椭球。在整个放顶煤过程中，顶煤边界旋转点高度在1倍支架高度范围内先增大后减小，而顶煤边界旋转角度逐渐增大。特厚煤层顶煤和矸石颗粒的位移场和速度场具有明显的非对称性。在过放条件下，当混矸率为10%左右时，可大幅度提高顶煤的纯回收率。提出了提高特厚煤层低温共轨开采顶煤回收率的相应措施，并提出了端部单开、中部双开的精细放顶煤开采技术，为特厚煤层低温共轨开采高资源回收率提供了新的途径。
Using longwall top coal caving (LTCC) in an extra-thick seam, many problems appear, such as large broken top coal blocks, frequent arch formation in the drawing process, poor balance of drawing top coal and low top coal recovery, which seriously affect safe, efficient and green mining. In this study, the size distribution of top coal blocks was measured in LTCC with an extra-thick seam firstly. Based on the measured result, discrete element calculations and physical experiments of the top coal drawing process were conducted to systematically investigate the mixed motion mechanisms of top coal and gangue blocks in an extra-thick seam. The results show that with increasing drawing height, the height-width ratio of the drawing body increases in a parabolic form, indicating that the drawing body shape gradually changes from a short fat sphere to a high thin ellipsoid. In the whole drawing process, the height of rotation points of the top coal boundary increases first and then decreases within a range of one times the support height; however, the rotation angle of the top coal boundary rise gradually. The displacement field and velocity field of top coal and gangue particles have significant asymmetry characteristics in an extra-thick seam. Under the excessive drawing condition, when the mixed gangue ratio is about 10%, the pure top coal recovery can be greatly improved. In addition, the corresponding measures to improve the top coal recovery are given in LTCC with an extra-thick seam; the fine caving technology is also put forward, that is, single-opening caving method at the end and double-opening caving method in the middle, which provides a new approach for high resource recovery mining in LTCC with an extra-thick seam.