Study On The Law Of Gas Emitting From Gob To Mining Coal Face Under Main Fan In Two Different Modes:Press In And Extract Out

There are two working methods of the main fan in the coal mine:the press type and the extraction type.Due to the various advantages of the extraction type ventilation in the actual production,and it is believed that the press type ventilation will increase the gas emission in the goaf when the main fan stops,so that the Baoding mining area of Panzhihua coal industry,which is dominated by the press type ventilation,is facing an uncertain problem in the management of the ventilation system for a long time.Based on this,taking the pressure ventilation system in Baoding mining area of Panzhihua coal industry as the research object,this paper studies the emission law of goaf gas to the working face under different pressure pumping ventilation modes.Based on mine ventilation theory,goaf seepage and gas migration theory,the integrated solution theory of mine ventilation network and gob flow field is analyzed,and the integrated solution technology of mine ventilation network and gob flow field based on i-MVS software is introduced.Through field observation and numerical simulation,the accurate basic parameters of ventilation system in Baoding mining area are collected,and the atmospheric pressure and gas emission in gob are observed.Based on the observation data and relying on i-MVS software,the numerical simulation study on the emission law of gob gas to the working face under different ventilation modes of pressure pumping is carried out.The results show that the variation law of gas diffusion coefficient with atmospheric pressure is the key parameter to quantitatively analyze the variation trend of gas emission intensity from gob to coal face after the main fan is shut down.The variation trend of gas diffusion coefficient can be obtained indirectly from the variation trend of atmospheric pressure before and after the fan is shut down;In the case of convection,the gas migration is dominated by convection,which has little to do with whether the mine adopts the press in type or the extraction type.The gas emission of the gob is almost the same in the same place after the fan stops.When the air is stopped or the air volume is reduced,the change of the atmospheric pressure of the mining face on the gas diffusion capacity is only 3.36%of the original diffusion capacity;After the main fan for press in operation stops,the air pressure of the working face will not change suddenly,but gradually decreases with time,and the gas expansion in the gob is 1.23%of the original volume.The applicability of the forced ventilation system in Baoding mining area depends on whether the mine management is convenient and whether other technical and economic indicators are reasonable,which has nothing to do with the gas emission in the gob under different ventilation modes.