Development of a water-mist based venturi system for dust control from maingate chocks and BSL

Advances in modern longwall (LW) technology have resulted in high production faces with more powerful chocks and shearers that can advance at faster rates. As longwall chocks (supports) advance, crushed roof coal and/or rock can fall from the top of the chock canopy into the face ventilation airflow. Dust survey showed that chock movement is a significant source of dust exposure for shearer operators, accounting for about 47% of total LW face dust make during the cutting cycle. 3D CFD models have been developed to understand the behaviour of longwall dust particles from various sources including maingate (MG) chocks and stage loader/crusher. Modelling results demonstrated that much of the respirable dust particles generated from MG chock movements and the beam stage loader (BSL) will disperse onto the longwall face ventilation, contributing significantly to dust exposure levels. Dust control systems using ultra fine water-mist technology have demonstrated promising results in encapsulating respirable dust particles. A prototype water-mist based venturi system has been developed to firstly produce ultra-fine water droplets (5-15 μm) for suppressing the respirable dust particles from the MG chocks/BSL; and secondly induce a water-mist airflow with sufficient momentum to divert dust clouds off the walkway area along the face. The new system will be trialled on MG chocks in medium to high seam longwalls on which dust contamination appears to be more problematic.