A common and frustrating challenge for underground managers to deal with is ensuring that wheel generated dust from underground haul roads is kept under control for the health and safety of the workforce.
A common method employed to suppress underground haul road dust in Australia is the use of fixed overhead sprinkler systems for preventative dust control. These systems will run the length of the roads beneath the surface, in particular along declines. These systems generally spray untreated water onto the roads in order to saturate the surface and prevent dust particles from becoming airborne.
However, this strategy has limited effectiveness and also a number of drawbacks.
For one, watering haul roads is only ever really a ‘temporary fix’. Inevitably, the road surface will dry out and will need to be re-watered. The flow-on is that this approach consumes enormous volumes of water, especially if sprinklers are left on during dry conditions or new portals to drier ore bodies are mined. In these conditions it's also common to find that quickly the opposite problem can manifest. Dry and dusty roads that are subject to excessive or poorly distributed spray coverage can quickly become boggy and slippery haul surfaces. flooding further into the mine can also occur and block silt traps adding further to maintenance and operating tasks.
Another limitation with using this method is that the sprinkler system needs to be reliable and provide complete coverage of the road network. Where spray coverage is patchy or incomplete, underground ventilation systems will pick up any airborne dust particles which are not suppressed. This causes dust to spread further throughout underground tunnels which is harmful to the health of workers and can lead to safety incidents due to poor visibility.
The patchy or incomplete coverage is often a symptom of spray malfunction, damage and poor maintenance . The systems are prone to damage from underground vehicle impact and If the sprinklers are not maintained properly and regularly, they simply do not work as intended. Repairing any such damage takes time and risks stoppages to haul production, which is seldom tolerated and as a result broken systems are neglected and eventually discontinued.
With all of the above issues with overhead sprinklers, (underground dust not being targeted properly, long term flow-on effects such as high maintenance costs and operational delays), it’s easy to see why many mines are looking for better strategies that will reduce costs, improve productivity and require less maintenance.
This is where Dust-A-Side can help.
What about spraying underground roads with surfactants?
Because dust surfactant chemicals are commonly used for dust suppression in underground transfer points and processing, it is also common to find them being applied to underground roads for dust control. However two major drawbacks occur when using surfactants as a road dust control solution.
Firstly, a surfactant is designed to make water wetter (breaking down the surface tension of water so it saturates material more easily), and without added binding agents to bind surface material there is no lasting dust control. As soon as the road dries the surface material remains loose and prone to accelerated fines and dust generation.
Secondly, what makes a surfactant chemical break down the surface tension in water is its industrial grade detergent properties. So adding a surfactant agent alone to underground roads can increase the risk of making them even more slippery when wet – especially if there is no tight control on product dosing and will do nothing to bind dust when the roads are dry.
Surfactants play an important part in suppressing dust that is already airborne and they are entirely appropriate for material transfer points or crushing, but without an added binding agent formulation they have little benefit for dust control on underground road surfaces.
OK, so what dust control treatment should be used on underground roads?
A far more effective approach to dust control underground lies in directly treating the road surface with the correct product technologies. Technologies such as road binders and bitumen emulsions are formulated to bind, stabilise and even seal road surface material to prevent fines that otherwise become hazardous airborne dust particles.
Particularly effective road binder products (such as DAS Product) are bitumen emulsions. This technology is specifically formulated to improve the road pavement quality, protect the structure of the road beneath while binding, sealing and suppressing dust.
Once applied, it forms a water-impermeable layer that doesn’t leach into the underlying natural soils, helping to stabilise the wearing course layers of the road. The binder also reduces equipment requirements and frequency for respraying and grading.
When correctly applied, DAS Product can significantly reduce the presence of airborne dust that risks being further distributed by underground ventilation systems.
How can DAS Product be applied to underground haul roads?
DAS Product can be applied via a series of light dilutions using a water cart . Once applied, and over time when a build up of bitumen binding content has been introduced the need for reapplication is minimal. This translates into significant reductions in: water usage, water cart requirements and frequency of interactions with maintenance vehicles in the decline.
Underground mines which typically rely on overhead sprinkler systems and switch to a road surface treatment like DAS Product will enjoy an environment with 90% less dust and reduce water usage by 95+%. What’s more DAS Product won’t leech or run to sediment traps once the bitumen cures in the road pavement. The technology remains as a solid once cured and in this state, can be easily reused and controlled.
For a more stabilised and robust pavement, DAS Product can be incorporated into the wearing course layer of the road via a process of grading, spraying and compaction. This not only provides excellent dust control properties, but significantly improves the durability and quality of the wearing course layer resulting in even lower ongoing maintenance costs.
Investing in DAS Product during the construction of new underground roads will significantly increase longevity and durability, which is particularly prudent for declines and on embankments surrounding the portal.
Want to learn more about using road binders on your underground haul road network?
We’ll provide you with a detailed cost analysis based on the size of your haul road network.
We’ll also provide you with figures showing how soon you’ll break even by engaging our services and how much you will be likely to save on operating costs.