Research and Engineering Application of Full-Section Fog Screen Dust Capture Technology in Return Airway

This study presents the development and numerical investigation of a full-section fog curtain dust suppression system installed in the return airway of a fully mechanized longwall mining face, designed to mitigate airborne dust emissions escaping from the return airway during coal extraction. To optimize nozzle selection, comparative experiments were conducted under varying water pressure conditions. A porous medium model was employed to represent the dust capture mesh, enabling a systematic analysis of the pressure drop and airflow resistance characteristics across a range of wind velocities; the model parameters—viscous resistance coefficient (D) and inertial resistance coefficient (C2)—were calibrated accordingly. Subsequently, coupled computational fluid dynamics simulations of fog dispersion and airflow fields were performed using a validated full-scale geometric model of the fully mechanized mining face. The influence of mesh pore size—via its effect on droplet size distribution uniformity—on the spatial distribution and velocity profile of the airflow field was quantitatively evaluated. The results show that the optimal spray nozzle was the fan-shaped atomizing spray nozzle, with a selected water pressure of 0.6 MPa. The droplet concentration in the porous media section increased from 0.026 kg∙m−3 to 0.052 kg∙m−3, and the volume share increased from 51.5% to 74.5%. The concentration of the filtered droplet increased from 0.00067 kg∙m−3 to 0.0013 kg∙m−3, and the size of particles adsorbed by the porous media increased from 140 μm in the proportion of most particles to 0.0013 kg∙m−3. The proportion of most particles above 140 μm was reduced to a range of 0–80 μm, and the optimal pore size was selected to be 100 mesh. Dust measurements were conducted at different measuring points in the return airway of the 25212 comprehensive mining face in the Hongliulin North plate area. The overall dust removal rates at points A, B, and C reached 88.90%, 83.71%, and 84.85%, and the respiratory dust removal rates reached 81.24%, 79.39%, and 80.33%, respectively, indicating that dust removal is effective.