Regardless of the type of material being handled (e.g. coal, ore, etc.) and the dust generating location (i.e. underground or above ground) the quickest, easiest and most effective way to control errant dust is with a dust suppression system.
Furthermore, a dust suppression system is an economical long-term solution that with regular maintenance can provide years of trouble-free performance.
Regardless of which system one chooses, be it a low pressure wetting system or high pressure misting system, nozzle selection is a vital consideration, right up there with the following considerations:
- Use of the right surfactant
- Spray pattern
- Spray angle, and
- Matching moisture droplet size to dust particle size.
How nozzles impact on dust misting systems
Nozzle capacity – together with liquid properties, spray pressure and spray angle – affect individual drop size.
Different nozzles produce different spray patterns with s a range of drop sizes: air atomizing nozzles under high pressure produce the smallest drop sizes followed by fine spray, hollow cone, flat fan and full cone nozzles.
It is important to ascertain the particle size of the dust, because dust capture is most effective when dust particles collide with water droplets of an equivalent size.
If the water droplet diameter is larger than the dust particle diameter, the dust particle will simply follow the air stream around the droplet. If both diameters are comparable, the dust particle will follow the air stream and collide with the water droplet .
There’s a very fine line here; water droplets that are too small evaporate too quickly and release the captured dust particles.
To assist you, Dust-A-Side has prepared the following “rules of thumb” regarding dust particle size.
Particle diameter in microns:
- Ground limestone: 10 to 1000 μm
- Fly ash: 10 to 200 μm
- Coal dust: 1 to 100 μm
- Cement dust: 3 to 100 μm
- Carbon black: 0.01 to 0.3 μm
- Pulverized coal: 3 to 500 μm
However, these figures may be dependent on the material and the material process.
As leaders in dust suppression systems, we can help you get the performance you need for your specific environment and operating conditions.
Want to learn more about nozzle selection in dust suppression systems?
For more information and advice about dust suppression, or to discuss the various types of nozzles available, please speak to one of our dedicated engineers today.
We’ll happily supply you with an obligation-free report to design a dust suppression system tailored specifically to your needs.
Call us now on +27 (0) 12 648 8900 or simply click here to contact us.