Technique for reducing methane concentration in the stope of the extraction site of a coal mine

Abstract

The article presents the results of research on means and techniques for increasing load on mining face of a coal mine which is constrained by a considerable methane emission from gas-bearing coal seams being developed, by the specified value of methane concentration in the outgoing longwall jet and air speed at mine working. Based on the analysis of the distribution of air flow masses in the longwall, it is established that there is a reserve for using air masses which move to the working face. It has been substantiated that, apart from preliminary degassing of the developed seam and improvement of ventilation schemes for mining areas, it is possible to increase the load on the longwall through using special pipelines. One of the pipelines (pressure line) is attached to the elements of the powered support directly at the bottom and cleans the atmospheric air in the longwall through the system of nozzles, whereas the other one (suction line), which is fixed on the side of the mined-out space, removes the polluted air with the help of the nozzles. Both pipelines are equipped with an individual air draft source. The technique has been developed to reduce the methane concentration in the extraction space by changing the turbulent characteristics of the ventilation flow by means of a pressure air pipe with dispersed fresh air supply and a suction air pipe with dispersed suction of outlet air, which are mounted along the longwall. This allows one to optimally distribute the air masses fed into the extraction space in cross section, and thereby increase the amount of air in the longwall, which, in turn, will significantly increase the load on the working face The efficiency of the proposed technique is confirmed by the results of studies on 3D models in CAD systems in the CDF software package. The developed technique for ventilation of the working face of the excavation area of a coal mine will allow maintaining the methane concentration and air velocity in the longwall within sanitary norms using the most powerful mechanized systems currently used in coal mining internationally.