Study on Efficient and Safe Mining Technology of Outburst Thick Seam

In order to solve problems of seriously imbalance during mining, low coal recovery rate, serious gas exceeding during upper layer mining, poor roof stability during lower layer mining when Qudi Coal field used pattern of slice mining in small face. When we use the mining methods of combining two small faces in lower layer, coal production increases by nearly 85 000 t, which accounts for 18.9% of annual. And the less of excavating two roadways and movement a time saves about 4.321 million yuan and shortens lots of time about working face preparation. Two rows of long boreholes cover the thick seam and carry out gas pre-drainage of upper layer and lower layer respectively. The concentration of gas in mining period is never over 0.6%, when a private gas tail roadway is served for the upper face. Roof of lower layer uses the type of ZYP3200/17/28 hydraulic support, which meets the maximum support pressure of 2 904 kN. The technology realizes slice mining efficient and safe mining in the outburst thick seam.