• Dust Management Technologies

For water spray or misting systems to be effective in controlling/suppressing airborne dust, the mist curtain efficiency and energy need to be matched to suit the product flow rate, the process-driven air flows, and any external disturbances, such as cross-winds, moving equipment or obstructions. Other factors that need to be considered for this purpose include dust PSD and concentration; water Droplet Size Distribution (DSD); nozzle design (e.g. air-water; water-only); water quality (e.g. chemicals, impurities); inertia and momentum of dust particles and air (including “gusts”); inertia and momentum of droplets; dynamic “balancing” of droplets with particle-air mixture; orientation (e.g. plant layout; dimensions).

his more scientific and engineering approach in solving difficult dust problems in the industry is being undertaken via a strategic R&D collaboration with EnviroMist Pty. Ltd. (e.g. conveyor transfers, crushing stations, ROM dump pockets, rotary rail car dumpers, and stacker/reclaimers). Another recent example of this collaborative effort involves solving a significant dust emission problem at a primary crusher ROM Bin, mainly due to truck dumping. An additional problem was the excessive amount of water used by the existing water sprays (up to 1000 liters/min), which were installed to reduce dust emissions.

the existing dust suppression system was not very effective. In some cases, depending on wind direction, the truck became totally consumed by the dust cloud. Using different nozzle performance characteristics. a 3D-CAD model was developed for the ROM Bin to optimize nozzle type, size, layout, spacing, and mist curtain efficiency. Additional design considerations included cross-wind effects and also reducing water consumption.