Application Practice of Downward Layered Drilling Technology for Eliminating Outburst in Coal Revealing
The main lifting shaft of Yangquan Coal Industry Group Boli Coal Mine Co.,Ltd.is an auxiliary shaft with a depth of 640 meters,mainly used for material lifting during production and personnel going up and down the shaft.To ensure effective removal of sludge and accumulated water at the bottom of the shaft in the later stage,it is necessary to construct a maintenance roadway at the bottom of the auxiliary shaft,which is the inclined roadway for cleaning the water pit at the bottom of the shaft.During the construction process,there is a 15#coal seam at the bottom of the roadway,with an average thickness of 5.3 meters and a risk of outburst.By using downward drilling and hole making before exposing the coal seam,and pre extracting coal seam gas,the gas content and pressure were tested to be below the critical value,effectively eliminating the outburst of the coal seam and ensuring the smooth construction of the roadway.
drilling through layersuncovering coalpre-pumping gas
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