Air and Dust Flow Patterns around the Longwall Shearer

Management of respirable dust on longwall faces remains a challenging issue for mine operators, particularly for the new generation of thick seam longwalls. It was identified that a fundamental understanding of the airflow behaviour around the shearer is critical for development of new dust control techniques. The main objective of the project was to conduct a detailed investigation of the air and dust flow patterns around the shearer on longwall faces using Computational Fluid Dynamics (CFD) modelling techniques. Development of a CFD model of a thick seam longwall face and conducting a series of modelling investigations to simulate the effect of various mining parameters and dust control options was the main focus of the project.

Three dimensional CFD models have been developed with cutting heights of 2.1m, 3.0 m and 4.5 m to represent longwall faces in thin, medium and thick seams respectively. Results from the base-case CFD models were calibrated and validated against field data obtained from Moranbah North, Central and Oaky No.1 Collieries. The modelled air velocity values and patterns are in good agreement with the velocity measurements from these operating longwall faces. The validated thick seam longwall face model was then used for detailed parametric studies to simulate the effect of various parameters and dust control concepts. The dust control options investigated include various spray configurations, shearer clearer, different cutting sequences, physical curtains and shearer scrubbers of various capacities to minimise the respirable dust migration towards the walkway area of the longwall face. This report presents the details and results of these CFD modelling investigations.

The project results indicated that the shearer scrubber and curtain combination system has good potential to reduce the dust migration towards the walkway area in longwall faces and is worthy of further detailed modelling and field studies to investigate the effect of various designs, in particular the size, shape, capacity, position and orientation of the curtains and scrubber in relation to the dust and face ventilation.