Conveyor belts use a wide variety of dust suppression systems depending on the materials and the source of the dust. Still, all of them rely on one basic principle: dust particles are more likely to interact with water particles of the same relative size.
This principle is true whether the dust is airborne or contained in the body of the materials being conveyed. In either case, the heavier particles created by bonding water and dust serve to keep the air within a conveyor clear, whether by pulling dust out of the air or keeping it weighed down in the first place. In the air, this effect is caused by the movement of air around droplets of water. The larger the drop, the greater the amount of air is forced to move around it, serving to carry the dust past the water without ever touching it. If the particles are the same size, this “slipstream” should be small enough that the two particles will come into contact and bond.
For maximum efficiency, a dust-suppression system’s water droplets must be kept within the specific size range of the airborne dust and in the same vicinity to provide the best opportunity for maximum interaction between the two.
More traditional water spray systems attempt to create appropriately sized droplets simply by spraying more water. Water-and-surfactant-spray systems improve capture efficiency lowering the surface tension of the water through the addition of surface-acting agents, controlling the wetting ability of the water, and reducing overall water needs. Fog and foam suppression systems rely on other methods – atomization and chemicals, respectively – to create the small droplets necessary to effectively capture the dust.
However, the choice between different kinds of systems depends largely on the kinds of materials being conveyed. This will determine the characteristics of the dust, including both the size of the particles and the nature of its interaction with water.
Certain materials, such as cement, cannot be mixed with water, and other materials bond poorly with water. This issue can sometimes be addressed through the use of surfactants. A suppressant chemical supplier should be consulted to determine the effectiveness of a given chemical with any specific material, as well as the broader ramifications of any dust suppression system.