Study On Dust Distribution Rule Affected By Dust Source And Dust Reduction Measures In Fully Mechanized Heading Face

Due to its high degree of mechanization,high speed of excavation,complicated equipment and long ventilation distance of the roadway,the dust concentration of the head face and the whole roadway is much higher than the safety standard.High concentrations of dust limit the work line of sight,increase equipment wear and pose a threat to the health and safety of workers.Aiming at the problem of high concentration dust control in comprehensive face excavation,this paper takes Yuhua Mine as the research object,and studies the factors affecting the distribution of wind flow field and dust field through theoretical analysis,numerical simulation and field measurement.Through optimizing the ventilation and dust removal method and adding a full-section dustproof system,the dust removal effect on the head face and the entire roadway is improved.The main research contents are as follows:Firstly,the geometric model was established according to the arrangement of the equipment of the comprehensive face-cutting face.The,flow field distribution of the fully mechanized face was measured by Fluent software.The wind speed decreases with the increase of the distance from the head face which is stable at 0.6 m/s after 35 m.The wind speed on the return air side is higher than the wind speed on the side of the wind tunnel.A low wind speed vortex area is formed around the heading machine and the driver working area.The dust source position is analyzed for the driver working area and the return air side.The influence of dust distribution also shows that the dust concentration on the return air side is higher than that on the air cylinder side regardless of the dust source position,indicating that the dust diffusion is mainly affected by the return air flow;the correctness and feasibility of simulation model are verified by comparing the simulation results with the measured data.Secondly,according to the excavation process,five representative points are selected as the dust source points in the simulation and the result is closer to the measured data than the simulation by a fixed dust source point,which shows that the method is more effective;the simulation method analyzes the influence of different ventilation methods and the distance of the air duct on the dust distribution law.When a single press-in ventilation is adopted,the dust concentration of the driver working area and the return air side is low when the air cylinder is 7 m away from the head surface;when combined ventilation(Dust-removing fan),the dust concentration on the head surface and the whole roadway is obviously reduced,indicating that the dust removal effect is better in this ventilation mode and achieves the best when the air cylinder is 13 m away from the head surface.Finally,in order to reduce the harm of the remaining unsettled small particle dust to the personnel in the waiting area at the warning line(25?30 m from the head face),it is necessary to set up the controllable spray and nuclear membrane prevention at this position.A full-section dust-proof system consisting of the dust nets enables the treatment of unsettling respiratory dust.The conclusion of this paper further deepens the understanding of the distribution of wind flow field and dust field in the fully mechanized face,and it is pointed out that the location of the wind field and dust source point will affect the dust distribution.By changing the distance of the air duct,using the combined ventilation of the pumping(dust removal fan)and setting the full-section dust-proof net can significantly improve the dust-reducing effect,which lays a foundation for further research on the intelligent linkage dust removal system.