Computational fluid dynamics modelling of respirable dust and gas behaviour on a longwall face

Longwall mining is the dominant form of underground coal mining methods in Australia. As production increases there is also a need for increased face ventilation rate for gas dilution and dust mitigation. The behaviour of gas emission and respirable dust in a longwall face is a complex process because of the nature of longwall operations. The generation, dispersion and transport of airborne dust and gas are governed mainly by the spatial velocity and the movement pattern of the ventilation air. To understand the gas and dust behaviour in a complex longwall mining environment and to evaluate the effectiveness of various dust control techniques, numerical modelling has become a necessity to supplement laboratory experiments and field studies. Three-dimensional (3D) computational fluid dynamics (CFD) model was developed based on a longwall face extracting a medium seam (3.2 m) to investigate the aerodynamics of methane gas emitting from drum cutting actions, and respirable dust from different sources. The model was developed to incorporate key features on the longwall, including the shearer, armoured face conveyor (AFC), chocks, outbye facilities and dust control devices. The base CFD model was calibrated using field ventilation survey data and used to study the behaviour of longwall gas and dust dispersion patterns that are vital to the safety and productivity of the longwall face.