Dust Control: Prevention, Suppression or a Bit of Both
Wet dust control systems use spray nozzles to apply humidity, water, and/or chemicals to:
- The dust source to prevent the dust from becoming airborne (wetting)
- Airborne dust particles to suppress or capture the dust and minimize the distance it travels
The system requirements for dust prevention are very different than the requirements for dust suppression even though both are applying moisture. It’s important to understand the differences between the two to ensure optimal performance.
When the goal is to prevent dust, the following factors must be considered to ensure a positive result
- Materials respond to moisture differently. For example, when applying moisture to ore, 3.5 liters per ton usually provides adequate wetting. On the other hand, coal repels water and will require the use of more moisture and chemical additives to increase absorption. Precision application of moisture is essential. Too little moisture results in airborne dust. Too much moisture may compromise the integrity of the material, cause costly production problems and equipment damage and create dangerous sludge – a maintenance nightmare.
- Most dust particles created during breakage are not released into the air. The dust stays attached to the material and adequate wetting is required to ensure it stays attached. Keep in mind that partially processed minerals and coal may be more sensitive to moisture than unprocessed material.
- If the material being sprayed is stationary, as on a storage pile, drop size and spray angle are critical. If the material is moving, as on a conveyor, drop size and drop velocity are the top concerns.