Study On Key Technical Parameters Of Water Injection And Dust Reduction In High Gas Mine

Coal seam water injection and dust-proofing technology is becoming more and more mature.It has become a conventional means of dust prevention at work face,and has formed a complete set of theory and practice system.When water is injected into the coal seam,a special water injection borehole is usually needed.In the high gas mine,the gas pre-drilling hole can be used to water the coal body,which does not affect the gas pre-pumping,and can avoid the waste of human and material resources caused by the re drilling of the water injection hole.But the effect of gas pre-Drilling on the water and production of coal body is unknown,and there are two main problems in the practical application process: on the one hand,because of the arrangement of gas pre-drilling,the water injection wetting range overlaps and the water phenomenon is serious in water injection;on the other hand,the key parameters of water injection are due to coal seam.The blind selection leads to the low efficiency of water injection.In view of the practical problems faced by the water injection in high gas mine,the movement power and state of water in coal seam and the key parameters affecting the effect of water injection are summarized through the theoretical analysis of the mechanism of water injection and the influence factors of coal seam.The relationship between the water content and the dust quantity further verified the necessity of the dust prevention in the coal seam of high gas mine.Through the theory analysis,the field data measurement and the numerical simulation,the layout of the pre-drilling hole and the selection of the key parameters of water injection are optimized,and the field water injection test is carried out to further investigate The effect of dust reduction in coal seam.The main results are as follows:(1)With the prolongation of the negative pressure time,the water content of each coal sample decreased gradually,the water loss rate was faster in the early stage,and the decreasing trend of water content gradually slowed down.Finally,it tended to a stable value,and the saturated water loss rate of coal samples was up to 70%.The amount of dust produced by dust increased with the gradual decrease of moisture content.(2)Considering the "one hole and two uses",the gas pre-drilling hole should adopt the plan of gas pre-Drilling and water injection interval arrangement,and the distance between the drilling holes is determined according to the geological conditions of different mines,and the 7m interval arrangement should be selected in this test area.(3)Pulsating intermittent water injection should be used for coal seam water injection.When selecting water,it is advisable to select the time node entering the limit stage of gas extraction.Water injection pressure,water injection rate and water injection time were comprehensively determined based on on-site investigation.