Dust suppression systems improve operator health and safety at quarry
A Somerset aggregate quarry wanted to improve health and safety for its personnel by minimising airborne dust. Particle clouds, formed during lorry loading and their onward drive out of the quarry, were creating inhalation and visibility challenges. Engineering equipment supply and maintenance specialist, Rotamec, specified and installed two water-based systems that resolved the quarry’s issue with minimal cost and energy use.
A constant challenge in a quarrying environment is dust, and it’s not just the aggregate particle clouds generated by cutting into the quarry bed. Loading aggregate onto trucks, followed by their movement out of the quarry towards the public highway, also creates a dust cloud. This not only impacts visibility, creating more challenging conditions for driving and operating machinery, but can also cause a health hazard for operators in the vicinity forced to breath in particle-laden air.
In this case, the safety-conscious employer wanted to investigate a way of reducing the dust generated by truck loading and transportation. Internal audits recommended minimising dust spread, which was exacerbated in the dryer summer months. The primary area of concern was the hopper bay, with lorries arriving below the hopper that would fill the trucks’ open box beds with aggregate, generating dust across the area in the process and impacting nearby personnel.
Quarry management investigated the potential of a physical barrier, using plastic strip curtains in an attempt to reduce the spread of dust outside the hopper bay. However, they had concerns over safety and effectiveness, including the curtain snagging on the lorry or the load, dislodging the material and trapping the curtain. Site engineers determined that a water-based dust suppression system would not only be safer, it would also be more effective at minimising dust spread. A water-based sprinkler system was also required along the quarry’s exit road to prevent dust spread from truckloads of aggregate leaving the site.
Quarry engineers contacted Rotamec, their long-term partner for the supply and maintenance of motors, gearboxes, and pumps, to design and install the required dust suppression systems. As a result of the installation, the system has significant reduced dust levels, with an energy efficient package that has improved working conditions as well as the health and safety of the quarry’s personnel.
Within the hopper bay, Rotamec specified and installed a self-contained mist system that automatically disperses water droplets to prevent the formation of airborne dust particles. Functioning with a timer, plus the options of remote as well as operator control, the dust suppression system pumps water at high pressure, up to 1,000psi, through 75 nozzles spaced up to 2m apart within the hopper area.
As the system only operates during and immediately after aggregate loading, it ensures low energy and water use, and the unit is fed via a standard 240V electrical connection plus a mains water supply. Constructed from stainless steel, the unit is sufficiently durable to withstand the demands of a quarry environment.
Providing dust suppression along the road exiting the site was more complex. Spanning a length of 40m, the scale of the requirement meant that Rotamec had to design a system that would generate and maintain sufficient pressure across the whole system to reliably prevent dust rise and accumulation. In conju
nction with pump manufacturer Calpeda, Rotamec specified a multi-stage pump that could ensure high water pressure across each of the system’s nine nozzles, fitted at 8m intervals. With a 5,000l capacity water tank, Rotamec engineers installed the complete system including all water pipes and electrical connections.
As dust suppression is only required when trucks are travelling along the road, the system is manually activated when required; although timed or sensor control options can be fitted for future requirement. When the system is activated, it generates water sprinkles that significantly minimise the rise and formation of dust along the 40m stretch, preventing particles from travelling back towards quarry operatives or out onto the public road.
The road dust suppression has resolved the issue and, like the mist curtain system, operates with efficient energy and water use. Involving a single pump, the system requires minimal maintenance and will be periodically inspected and serviced by Rotamec to ensure optimal ongoing operation.