Simulation experiment on the pneumatic filling of gangue in coal auger mining

This study proposes to address large coal pillars reserved in coal auger mining and coal seam collapse during extraction. We adopted the gangue gas filling process of coal auger mining and set up the experimental platform of pneumatic conveying with different pipeline lengths and arrangement forms based on the actual working conditions underground to simulate the pneumatic conveying conditions of feeding, gangue conveying, filling and receiving in the roadway. This experiment recorded the state of movement, crushing situation and static pressure changes of flow field of gangue particles to investigate the relationship between particle movement state and static pressure of flow field. We found that 1) the maximum static pressure in the pipe reflects the number of particles in the first pile; 2) the distribution of particles crushing increases with increasing particle size; 3) the fluctuation of static pressure in the flow field is more violent with increasing particle size after crushing; 4) the effect of different pipeline configurations in long-distance conveying on conveying time and the use of cyclone intensifier to improve the conveying capacity of the long-distance pipeline. This study provides an methodological reference to the industrial promotion of underground gangue pneumatic filling systems.