Underground » Health and Safety
The overall aim of the Dust Suppression Project is to develop a system to improve airborne dust control in underground coal mines based one electrostatically charged water sprays. The benefits of reduced airborne dust levels will be a lesser risk of lung disease in coal miners, improved working conditions and a reduced risk of dust explosions.
Design constraints for a practical and safe electrostatically charged water spraying system, suitable for mounting on a longwall shearer, were identified and design criteria for efficient dust suppression defined. Induction charging was identified as the preferred method of charging and air atomisation as the preferred atomisation technique.
Two items of laboratory testing equipment were developed: the spray charger / collector, an apparatus to investigate the generation of electrostatically charged water sprays, and the coal dust scrubber, an apparatus to investigate the ability of electrostatically charged water droplets to capture airborne coal dust. A preliminary program of experiments with a prototype induction-charged air-atomising nozzle was undertaken and the result used to validate a new theory which had been developed to predict the behaviour of such nozzles.
It was also demonstrated that the induction-charged air-atomising nozzle is able to impart a significant electrostatic charge onto water droplets and that both total and respirable dust can be almost halved. Furthermore, it was also shown that an electrostatically charged water spraying system can be operated safely in an environment of wet coal dust.
The tasks and objectives of the ACARP funded stage of the Dust Suppression Project were all achieved. Work on the project is continuing, supported financially by the Joint Coal Board Health & Safety Trust.