Study On Dust Pollution Regularity Of Cutting And Dust Control In Spray Field In Fully Mechanized Mining Face With Large Mining Height

Fully mechanized mining face is one of the places with more dust production in coal mine.Especially in the process of coal cutting,the instantaneous dust concentration of individual working places is as high as 4000-6000mg/m3,which is far beyond the stipulation of "Coal Mine Safety Regulations".Because of the large diameter of shearer drum,the dust production of large mining height fully mechanized mining face is higher than that of common working face,and the wide mining height environment makes dust in the working face.Dispersion direction and law are more complex,which leads to dust control in fully mechanized mining face with large mining height has always been a difficult problem in coal mine safety production.In this paper,based on the basic theory of dust particle movement,the dynamic characteristics of cutting dust are analyzed,and the air-dust coupling mathematical model is constructed by using Realizable model and particle force model.The primary atomization model of spray liquid film breakage is determined and the probability of droplet collision is calculated by collision volume.Based on the analysis of the two breakage mechanism of droplet,the two atomization model of K-H unstable surface wave is defined,and the whole process model of jet atomization fragmentation is constructed.Based on the air-dust coupling model of fully mechanized mining face with large mining height,the air flow characteristics of shearer drum at different cutting positions and the microscopic diffusion law of dust with different particle sizes are analyzed and obtained.The first and second peaks of dust concentration in pedestrian respiratory zone are found.The relationship between Pdt(where dust particles enter the sidewalk)and Prl(distance between the axis of shearer and the air entry lane)is given.The concentration distribution and regional difference of settlement of dust with different particle sizes in fully mechanized mining face with large mining height were studied.Through the actual measurement of air flow in 5301 fully mechanized mining face of Tangkou Coal Mine,the accuracy of the simulation results of air flow field is verified.The atomization characteristics of SS1.6mm and SS2.0mm nozzles under different pressure conditions were determined by atomization characteristics experiments,including atomization angle,effective range,particle size and flow rate.Combined with the analysis of atomization angle and flow rate parameters,SS1.6mm and SS2.0mm nozzles were selected.Finally,the layout of the spray field of the hydraulic support spray area of the fully mechanized mining face with large mining height and the layout of the fog field outside the spray area of the fully mechanized mining face were formed,and the detailed installation and implementation method of the optimization plan were elaborated in detail for the 5301 fully mechanized mining face of the coal mine.The operation mechanism of the spray operation group of the fully mechanized mining face with large mining height was defined,and the coverage degree of the whole section and the uniformity of droplet distribution were obtained.The optimum scheme is evidently superior to the field scheme in terms of droplet size D[4,3].The field application results show that the new fog field dust control technology can effectively alleviate the coal dust pollution in the working face.The average total dust reduction rate of each working procedure is 85.6%and the average exhaled dust reduction rate is 83.9%.Compared with the traditional dust reduction measures,the dust reduction efficiency of the working face has increased by 27.9%and 35.3%respectively.