Open Cut » Health and Safety
This Report offers a summary of current practice of haul road dust suppression in the Australian coal industry and makes recommendations for improvements.
The findings of the Project are based on a inspection of haul road construction and dust suppression practices at eight coal mining sites in NSW and QLD; discussion of related technology and safety issues with site engineering and workplace health & safety staff; interviews with the senior people in the industry and the technology providers; and a literature survey of moisture and dust sensing technologies.
Regular application of water by water trucks trafficking the haul circuit is the most common dust mitigation method. Most sites use pit water for this purpose. Such water is generally not scarce and, in fact, haul road watering is considered as an outlet for disposing of pit water. None of the sites monitored the amount of water used in haul road dust suppression. Lack of baseline data makes it difficult to evaluate the efficacy of trials with chemical additives carried out at some sites.
Watering rates observed during this project ranged from 0.3mm to 1mm film thickness. High application rates apply when the water flow is not reduced while the truck slows down. Past studies suggest watering rates of 0.3 to 0.5 mm. Different film thicknesses may need to be applied under different climate, traffic and road surface conditions. The existing technology of linking the pump speed to the truck engine speed cannot deliver such control.
Five of the eight sites visited had written guidelines on haul road watering practices. The other three relied on on-the-job training for new operators. The written watering guidelines from different sites were quite similar.
As haul road watering practice has been found to vary across the industry, improvements can be achieved at most sites by adopting the industry best practice. At the same time, there is potential to significantly improve the best practice through a continuous review of existing established processes as well as by trying and adopting new technologies.