Stockpile & Stacker Dust Control
The solution to suppressing stockpile or stacker dust depends on many factors including:
- material characteristics - material type and lump or fines
- how the material behaves when wet - crust or slush
- material processing sensitivity to additives
- availability of water & water quality
- feasibility of installation of spray system
- stockpile turnover frequency
- stacking and reclaiming method
The dust from stockpiles is from the stacking or reclaiming process or from wind blowing across the static stockpiles. The following are solutions to that individually control stockpile dust but in most cases a combination will be the best solution.
Wind Fences & Dust Fences
The biggest challenge with managing stockpiles dust is the wind. Wind Fences reduce the wind speed which prevent dust lifting off stockpiles, minimise the travel of dust generated during stacking and reclaiming and improve the performance of other dust control solutions such as Fog Cannons.
Wet Earth offers both Wind Fence and Dust Fence solutions as listed below. These are both quality solutions, but have significant differences. Please follow the links for more technical information on each solution or visit our page which compares wind fences and dust fences.
Wind Fence: DSI DustTamer Wind Fence
Dust Fence: DustTexNet Dust Fence
Telescopic Stackers are used to keep the falling material enclosed between the stacker discharge point and the top of the stockpile. These are generally used for stockpiles that have a single discharge point. They can be manually adjustable or have their height automatically controlled by the height of the stockpile.
In many cases they have a rubber skirt which lays on the stockpile surface providing a seal between the stacker and stockpile which significantly reduces the dust that escapes.
Wet Earth does not offer this solution, but we do recommend them as they can have a significant reduction in dust generated during stacking.
Dry Fog Dust Control System
Dry Fog is a very efficient system for suppressing airborne dust, but it is limited in its coverage distance due to the tiny droplets. As a result it use it limited to, but very effective in suppressing dust generated at the bottom of telescopic stackers and is particularly useful for shiploaders due to its low water volume and efficient dust suppression.
Follow the link for more information on Dry Fog Dust Control.
NESCO Dust Control Spray System
Adding moisture to the surface of the material it reduces its dustiness (ability to release dust). This is not necessarily bringing the material to its Dust Extinction Moisture (DEM) level but bringing the material surface to its DEM. The NESCO system delivers the right amount of water in the best way to get even distribution through the material.
A NESCO Dust Control Spray System reduces the materials ability to generate dust and it always easier to prevent dust than try to suppress dust once it is airborne.
Follow the link for more information on NESCO Dust Control Spray System.
Stacker Discharge Sprays
Stacker discharge sprays attempt to suppress airborne dust that is generated as the material falls from the discharge point to the stockpile. These are generally inefficient due to either the water droplets being too small and blown away without suppressing the dust generated over the full drop of the material or the droplets being too large to actually suppress the airborne dust. See information on matching droplet size to dust particle size on our Dust Control Theory page.
We recommend that if water is to be used then it is moved back into the head chute applied to the material itself using a system like the NESCO Dust Control Spray System above.
DEM Modifier Chemicals
There are new chemicals that can be dosed into water spray system such as the NESCO above which can significantly decrease the amount of moisture required to control dust. The amount of chemical required is small (ie 200ml per ton of ore) and they typically achieve a DEM reduction of about 2% (eg water required for DEM decreases from 5% to 3%). They are particularly useful for fine material that has problems holding moisture (ie can become fluid) or become difficult to handle (ie become sticky) before they reach their DEM. The benefit of these additives stays with the material through the transport system and provide dust suppression benefits at every handling point.
We have a range of chemicals for different material types so please contact us to discuss your application.
Stockpile Spray System
Suppressing the dust from the surface of the stockpile is simply a case of stabilising the surface of the material. This is usually done with regular watering. Wet Earth has a range of long throw, high angle sprinklers which are suitable for stockpile dust suppression. We can also provide the full solution including sprinklers, valves and control system.
Please follow the link for more information on Stockpile Dust Control Spray Systems.
In cases where either the material can not get wet or the action of adding or removing material generates an unacceptable amount of dust then Fog Cannons™ are the recommended solution. Fog Cannon performance can be severely impacted by wind so they are commonly used in conjunction with wind fences. Wet Earth is the exclusive distributor of Fog Cannons™ in Australia.
Please follow the link for more information on Fog Cannons.
Crusting agents can prevent the lift off of dust from stockpile surfaces. They are particularly useful in high wind areas with exposed stockpiles. Different application rates can be used for short or long term crusting based on the expected turnover rate of the stockpiles. Their use is limited for stockpiles where the surface is continually changing (ie single stacking point active stockpiles), but they can provide protection from high wind events. They can be applied using high volume sprinklers or any water application systems.
Wet Earth has three crusting agents that it uses for these applications. For more information including a comparison and discussion of surface crusting visit our Crusting Chemicals Soil & Binders page.
Please call us on 02 6062 3300 or email email@example.com to discuss your stockpile dust control project.