Practices on Gas Emission Control of Coal Mining Face with Close Distance to Upper Protected Seam

In order to realize a safety and high efficient coal mining in the No.5121 (5) coal mining face with a close distance to the upper protected seam, base on the ground stress main leading type outburst danger features of the thin seam, the gas emission conditions of the coal mining face and the adjacent seam were analyze d.The Y type downward ventilation method of the gateway retained along goaf in the No.5121 (5) coal mining face was designed.Under such condition, the gas migratio n law of the coal mining face with a close distance to the upper protected seam was studied.The gas drainage with borehole drilling through the roof (floor)，the gas dra inage with borehole from surface ground, the gas drainage at the mining face end gateway and several gas drainage methods were provided.The gas drainage effect of the coal mining face and the gas emission accumulation status of the No.5121 (5) coal mining face were investigated.The results showed that the gas volume fraction d uring the mining process of the coal mining face in the protective seam would blow 0.6% and the pressure releasing and gas pre-drainage rate of the protected seam W ould reach at the 70.1%.According to the coal mining face with the ground stress main leading type outburst danger in the thin seam, the application of the downward V entilation technology was feasible and could meet the mining requirements of the coal mining face with a close distance to upper protected seam in combined with the r ational pressure releasing and gas drainage method.