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.