Analysis of dust pollution effect after blasting and dust removal parameters under hybrid ventilation in digging face

In order to reduce the dust pollution produced by metal mine tunneling after blasting operations, as well as to solve the optimization problem of hybrid ventilation and dust removal parameters, to enhance the working conditions at the construction site and safeguard the health of workers, a study was conducted focusing on a metal mine in Yunnan. The study developed a hybrid ventilation model for roadway blasting and tunneling, using Fluent software to examine airflow distribution, dust dispersion, and sedimentation behavior in the tunnel. The study also examined how varying distances between air inlets and outlets, as well as different air volumes, affect dust distribution under hybrid ventilation. Additionally, gray correlation analysis was used to examine the connection between the time needed to lower dust concentration to safe levels and the relevant influencing factors. Findings indicate that with hybrid ventilation, the airflow in the roadway is segmented into three zones: vortex, transition, and stable areas, and the average wind speed of the roadway section will show a trend of increasing and then decreasing, and then decreasing to about 0.22 m/s and gradually stabilizing. Before ventilation 1 min, dust diffusion speed is faster, after ventilation 1 min, dust diffusion speed is slower. Dust with particle size above 35 μm from blasting will be settled closer to the face, while dust particles smaller than 35 μm are carried away by the airflow or extracted from the tunnel due to the influence of the wind. Through comparative analysis, it can be seen that the air outlet of the press-in type wind pipe is 10 m away from the face of the excavation, when the air inlet of the exhaust-type wind pipe is positioned 5 meters from the excavation face, the ventilation and dust removal efficiency is significantly improved. Additionally, a pressure-to-extraction ratio (m) of 0.8 to 1 yields better dust control results. Their respective gray correlation coefficients are 0.732, 0.648, 0.630, and 0.621.To enhance the post-blasting environment in the roadway, optimizing hybrid ventilation and dust removal parameters should prioritize adjusting the air volume at the outlet of the press-in type wind pipe to improve dust removal efficiency.