Causes And Prevention Of Low Oxygen In The Working Face Of Bulianta Coal Mine

In recent years,low-oxygen phenomenon has become more and more prominent in some low-gas mine faces in Shendong mining area and Shanxi Province,and the low-oxygen safety problem has affected the normal stoping of the working face.At present,there are few systematic studies on this aspect,so it is necessary to carry out research on it in order to take targeted prevention and control measures.When the hypoxic phenomenon occurs,the high concentration of N₂ is dominant.Previous studies mainly studied the causes of high concentration N₂ emission from goaf to working face,and proposed various prevention and control measures to reduce the amount of low-oxygen gas emission according to different influencing factors.However,there were few studies on the micro causes of low concentration O₂ in large areas of goaf.This paper takes the Bulianta Coal Mine in Shendong Mine as the research object.According to the phenomenon of hypoxia in 22411 working face,the factors affecting the low-oxygen gas emission were analyzed and summarized.Through the experimental study,the main causes of hypoxia in the goaf were explored,and the theoretical and feasible prevention and control methods were put forward.The main research contents and results are as follows:?1?The characteristics of the hypoxic phenomenon were discovered,and the existing hypoxic prevention and control measures were summarized and analyzed.Comparing the conditions of the working face where hypoxia occurs,the common characteristics are obtained:the atmospheric pressure changes affect the outflow of low oxygen gas in the working face;the shallow buried coal seam is prone to low oxygen phenomenon;the negative pressure ventilation promotes the low oxygen gas to flow from the return air corner out;the presence of adjacent mined-out areas has an impact on the severity of hypoxia.Among the existing low-oxygen prevention and control measures in the mine,the ground fissure landfill measures and pressure equalization ventilation measures have a better control effect.?2?The reason of low oxygen emission in 22411 working face was obtained.By analyzing the correlation between the change in the oxygen concentration at the return corner of the working face and the pressure and temperature changes in the22411 working face,the reason for the low oxygen emission in the working face of the22411 working face is obtained:the increase in atmospheric temperature leads to the decrease in atmospheric pressure,which affects the pressure drop in the working face,which leads to The low-oxygen gas in the empty area rushes to the working face;the coal seam is buried shallowly,and the cracks developed by the mining surface are likely to form air leakage passages with the goaf,intensifying the generation of low-oxygen gas in the goaf and promoting it to the side of the working face Migration;negative pressure ventilation promotes the migration of low-oxygen gas in the goaf to the working face side;the air leakage channel formed by mining-induced fractures between the adjacent goaf and the goaf may have gas migration,resulting in the increase of low-oxygen volume in the goaf.?3?The main causes of low oxygen gas in goaf of 22411 working face were obtained by experiment.Through short-term and long-term experiments on changes of air pressure and oxygen concentration in a confined space containing coal,it is found that air pressure decreases and oxygen concentration continues to decrease in a confined space.The final detection result of each gas concentration was that O₂ decreased,N₂ increased,and CO₂was produced less.Based on this analysis,it was concluded that the main reason for the low-oxygen gas in the goaf was the adsorption of O₂ by coal.?4?The adsorption capacity of different coal samples to CO₂,O₂ and N₂ was obtained,which further proved that the main reason for the generation of low-oxygen gas in the goaf was the adsorption of O₂ by coal.By studying the adsorption and desorption characteristics of coal on O₂,N₂ and CO₂,the adsorption?desorption?capacity of coal sample on working face 22411 is CO₂>O₂>N₂ from large to small.By comparing the O₂ adsorption test results of different coal samples,it was found that the adsorption capacity of different coal to O₂was different.The reason for the difference is related to the specific surface area and pore capacity of the coal,which further proves that the main reason for the generation of low-oxygen gas in the goaf is related to the adsorption of O₂ by the coal.?5?In view of the low oxygen phenomenon in 22411 working face,two feasible control methods are proposed.Using CO₂ to hinder the adsorption of coal to O₂.Firstly,competitive adsorption experiments were carried out on mixed gases with different proportions of CO₂ and O₂.It was found that the amount of O₂ displaced first increased and then decreased with the increase of CO₂ concentration,reaching the maximum at 10%.Then,a small experiment of CO₂ injection hindering the adsorption of O₂ by coal was carried out,and it was found that CO₂ had a certain effect on hindering the adsorption of O₂ by coal,which requires further research and testing.Through the on-site data analysis,the prediction parameters for predicting the occurrence of hypoxia were obtained.A model was proposed to analyze the prediction relationship of these parameters to the occurrence of hypoxia,and related method steps were formulated.The paper contains 40 figures,13 tables and 55 references.