Gas–solid flow characteristics and airflow in blind tunnels of underground hard-rock mines

Abstract

Efficient airflow and dust control are major challenges in blind underground hard-rock tunnels due to uneven airflow and stagnant zones that increase gas and dust. In this study, gas–solid flow characteristics for dust diffusion in a 40-m blind tunnel were investigated using a coupled Euler–Lagrange computational fluid dynamics–discrete element method. Fine dust particles (1–7 μm) were released under varying turbulence and thermal conditions, with inter-phase forces between airflow and particles fully modelled and turbulence-driven particle diffusion captured using a discrete random-walk approach. Analysis of airflow velocity, pressure, temperature, and turbulence revealed pronounced non-uniformity, localised high speed jets up to 62.5 ms⁻¹ due to geometric constriction at duct outlets, and extensive stagnant regions. Dust simulations showed fine particles remained suspended in low-velocity zones, whereas larger particles settled rapidly. A hybrid-duct configuration generated highest turbulent kinetic energy (≈9.4 m²s⁻²) and provided most effective momentum-driven mixing.