关键词: 下向进路采场, 采场炮烟, 数值模拟, 扩散特征, 通风井位置, 进路长度

Abstract:

To definite the diffusion characteristics of blasting fumes in downward drift filling mining stopes, taking the downhole filling mining method of Longshou Mine in Jinchuan as an example, numerical simulations and field tests were conducted. The spatial distribution of airflow in drifts and layered roads was studied,and the diffusion patterns of CO and NO₂ in drifts were analyzed. Furthermore, the effects of ventilation shaft locations and drift lengths on CO diffusion were explored, and the ventilation parameters of the Longshou Mine were determined. The results indicated that the airflow field in drifts and layered drifts can be divided into the inflow zone, neutral zone, and return zone. The airflow velocity in the drift. shows the S-shaped distribution, with higher velocity at the bottom, lower in the middle, and moderate at the top. In the vertical cross-section of the drift, the CO volume fraction continuously increases with height. While horizontally, it exhibits a "decrease-then-increase" pattern from the inner to outer side. At the drift waistline, the CO diffusion velocity shows a logarithmic decreasing trend with ventilation time.NO₂ is primarily concentrated below the midline of the drift, and its diffusion velocity is significantly faster than that of CO. The CO diffusion rate is negatively correlated with both the distance from the ventilation shaft to the drift entrance and drift length. When the distance between the ventilation shaft and the drift entrance is ≤40 m, and the drift length is ≤55 m, the CO and NO₂ concentrations in the natural ventilation blasting fumes are below the standard limits below after 30 minutes.

Key words: downward drift stope, stope fumes, numerical simulation, diffusion characteristics, ventilation shaft locations, drift lengths