Gas-solid two-phase flow at high-gassy fully mechanized within high gassy coal seam

To solve the problem of high dust concentration around the heading face area at a high gassy fully mecha- nized heading face under forced ventilation conditions,the 2601 high-gassy fully mechanized heading face at Zhangcun Coal Mine of Lu’ An Group was taken as the research case. Based on the theory of gas-solid two-phase flow and through programming,the dust carried by air migration process at the fully mechanized heading face was calculated, and the gas-solid two-phase flow law in the heading area at the fully mechanized face was investigated. The results show that there is a negative pressure zone between the outlet of the ventilation cylinder and the heading face,whose influence range increases with the wind velocity of the outlet of the cylinder. With the increased negative pressure zone,the center pressure decreases as the wind velocity increases. Due to the pressure difference in the negative pres- sure zone,part of the dust flow moving along the opposite side of the air cylinder flows under the vortex above the road header and the backflow of the road header,and flows through the road header from the right and rear of the road header. Then the dust gather away from the heading face 2. 5 m in the inlet side,resulting in a higher dust concentra- tion at the right and rear of the driver and away from the heading face 2. 5 m in the inlet side. When the wind velocity at the exit of the air cylinder is less than 17 m / s,the return dust forms a dust belt with an average quality concentra- tion being 300 mg / m3 around the road header,when the wind speed is greater than 17 m / s,the average concentration of the dust belt drops drastically,and the return dust is at the outlet of the air cylinder. It was accumulated to form a dust cloud having a quality concentration of exceeding 300 mg / m3 . Therefore,a dust intercepting device should be in- stalled on the return airflow side of the roadway of high gassy fully mechanized heading face to prevent the dust from moving along the return airflow side to the rear of the working face. Also,a dust removal device covering the cross sec- tion of the working face should be arranged at the rear of the road header to intercept the dust moving along the return airflow side,block the dust backflow behind the road header,and improve the visibility of the heading face.