Fugitive Dust Suppression at Conveyor Transfer Points
Of the five primary sources of fugitive dust, conveyor belt systems generate between 30 and 60% of the total airborne particulate for a given plant.
Fugitive Dust Emission Sources
| Reclaiming | 0 – 10% |
| Crushing | 1 – 15% |
| Screening | 5 – 10 % |
| Stock Piling | 10 – 30 % |
| Belt Conveyor Systems | 30 – 60 % |
Considerations of Water-Spray System
Dust particles need to be trapped before becoming airborne therefore proper wetting of the broken material on the conveyor belt is critical.
The drop size distribution of a spray nozzle is the most important variable for effective dust suppression. Typically conveyor systems spray nozzles with coarse drops of 200 to 500 microns are recommended. For airborne dust suppression, very fine drops of 10 to 150 microns.
Nozzle spray pattern should be selected based on spray nozzle placement.
• FullJet® nozzles– produces larger drops that maintain velocity over a distance. They are useful when nozzles must be located at increased distance from the application point or to clear mechanical obstructions.
• WhirlJet® nozzles – drop distribution is typically smaller than most other hydraulic sprays. They are useful for operations where dust is widely dispersed.
• FlatJet® / VeeJet® nozzles – produce relatively large drops. These are especially useful for belt cleaning applications and should be located in opposite direction of travel.
• FogJet® LN Fine Spray nozzles – create very fine drops produce the most surface area per liter for increased wetting and are typically used for airborne dust suppression systems.
Water quality – water hardness increases surface tension of water and may increase the amount of water needed for adequate wetting. Consider free passage of the type nozzle selected for the application. Contaminants such as suspended or dissolved solids in ponds, river water or reclaimed water sources may influence the nozzle selection process. Consider filtering water to less than 50% of the free passage size of the nozzle, to reduce nozzle wear, clogging and maintenance.
Water quantity – the amount of water needed for any dust control or dust suppression application is based on mass flow of the material and is application specific. Water flow rates are generally between 0.5 and 1.5% by weight of the material flow.
Nozzle Location
• Accessible for ease of maintenance
• Clear of falling material
• Nozzle should be upstream of transfer point of where the dust emissions are being created.
• For airborne dust suppression, the nozzles should be located to provide maximum time for water drops to interact with fugitive dust