Key technology and practice of gas extraction in steep extra-thick coal seam

In order to reduce the influence of gas on the safety production of steep extra-thick coal seam in Wudong Coal Mine, the application of horizontal slicing fully mechanized top coal caving technology in steep extra-thick coal seam was studied.The influence of drilling parameters such as hole spacing, drilling diameter, effective length and drainage negative pressure, as well as gas drainage technology on the drainage effect were analyzed.Based on the technical means of gas pre-drainage by long borehole along coal seam, gas drainage, roof strike high borehole drainage, buried pipe drainage and pressure relief, a complete set of three-dimensional gas drainage technology system is established, which combines gas drainage by mining layer and lower coal mass of mining layer, providing theoretical basis and guidance for the establishment of coal and gas co-mining system in steep extra-thick coal seam.