Research On Explosion Characteristics Of Coal Dust Under High Temperature Condition In Deep Shaft

With the increase of mining depth,the temperature of raw rock keeps rising,which makes the high temperature heat damage of coal mining face become a serious threat to coal mine safety production.At present,the most widely used coal dust prevention and control technology are mostly based on water.After coal dust wetting and settling,the evaporation rate of water is accelerated in high temperature environment,and it becomes dry again in a short time,which can easily cause secondary dust float.In addition,dry coal dust is at risk of explosion in the event of an accident such as impact pressure or coal and gas protrusion in a coal mine.This paper takes four coal mines of Ping Ding Shan Tian An Coal Co.Ltd as the research object,and studies the influence law of deep well high temperature on coal dust moisture evaporation characteristics through wetting coal dust moisture evaporation experiment.The influence of industrial composition and water content on the explosive characteristics of coal dust was studied by using 20 L spherical explosive device.Finally,combined with the experimental results of the four mine hex 15-31060 mining face comprehensive dust control system research and improvement.The process of moisture evaporation can be divided into two stages: evaporation and water loss equilibrium.The higher the ambient temperature is,the shorter the time to reach evaporation equilibrium is.The evaporation rate of coal dust moisture at 50℃ is 2 times higher than that at 25℃ on average,and the maximum water loss rate rising by 24.57%.There is a significant positive correlation between the volatile content of coal dust and its explosive characteristic parameters.With the increase of fixed carbon content of coal dust,the coal dust explosion characteristic parameters increase first and then decrease,and the critical content is 54%.The moisture content of coal dust inhibits the explosive characteristics of coal dust.With the increase of moisture content of coal dust,the maximum explosive pressure,the maximum pressure rise rate and the explosion index of coal dust decrease obviously.The maximum explosion pressure,maximum pressure rise rate and explosion index at 20% moisture content decreased by 41.25%,60.25% and 62%,respectively,compared with dry conditions(0% moisture content).This paper establishes the relationship between the volatile content and fixed carbon content of the industrial fraction of coal dust and its explosion characteristics parameters,and reveals the effect of deep shaft temperature variations on the evaporation characteristics of wetted coal dust,and analyses the influence of the water content of coal dust on their explosion parameters.This paper provides a scientific basis for coal dust explosion protection technology in high temperature mines.