3-D movement law of top-coal in near horizontal coal seam with multi-gangue under caving mining technique

Abstract

The spatial shape of coal-gangue draw body and 3-D distribution of top-coal recovery ratio were studied by 3-D similar simulation experiment and numerical simulation analysis based on the loose medium flow field theory. The results show that the drawing volume of top-coal caving face in near horizontal coal seam with multi-gangue increases from upper face end to lower face end, while the rock-mixed ratio decreases accordingly, and the lower face end has a higher drawing efficiency; the top-coal recovery ratio zoning presents dynamic evolution process along the coal seam's strike direction and periodic distribution along the dip direction; the relationship between volume of coal-gangue draw body and drawing height presents a power function; the top-coal recovery ratio and rock-mixed ratio show the stages of change with the drawing time, and the interval drawing method can improve the top-coal recovery ratio of multi-gangue coal seam.