Influence of air quantity on dust migration and distribution during coal cutting operations at a longwall face: An experimental study

To improve the efficiency of dust control during coal cutting at longwall faces, this study experimentally investigates the spatial distribution characteristics of dust and the influence of air quantity on dust migration. First, the study establishes similarity criteria for dust transport based on similarity theory. Using a coal mine in Shaanxi Province as the prototype, the study constructs a scaled experimental platform with a complete intake–return ventilation system (scale ratio 5:1). The study then simulates dust generation during longwall cutting operations and analyzes dust concentration distribution and particle size evolution under different ventilation conditions. The results show that dust transport satisfies two similarity criteria: Π 1 = v g 2 / gl and Π 2 = d p / l . After longwall mining with a shearer, both suspended dust concentration and dust deposition rate in the face-side operating zone and the longwall walkway area follow an exponential decay pattern. Due to the characteristics of the airflow field, dust concentration in the face-side operating zone remains consistently higher than that in the longwall walkway area within the same cross-section, and its decay rate is slower. Dust deposition mainly occurs within 10 m on the leeward side of the shearer in the face-side operating zone and within 20 m in the longwall walkway area, with a higher deposition rate observed in the face-side operating zone. The mean particle size of both suspended and deposited dust increases with distance following a power-law trend. Suspended dust particles in the face-side operating zone are slightly larger than those in the longwall walkway area, but both remain within the range of 10–15 μm during the steady stage. Within the same cross-section, the mean particle size of deposited dust is typically more than twice that of suspended dust, and this difference becomes more pronounced closer to the dust source. Air quantity significantly regulates the spatial distribution of dust on the roadway. As air quantity increases, dust concentration and deposition rate in the face-side operating zone decrease markedly, while dust concentration in the longwall walkway area increases due to entrainment effects. Both suspended and deposited dust particle sizes show a positive correlation with air quantity, indicating that higher airflow velocity enhances the transport and entrainment capacity of coarse particles. The findings provide theoretical support and experimental evidence for optimizing ventilation and dust removal parameters in longwall faces.