Haul Road Dust Control Chemicals
There are a large range of different chemicals used on mine haul roads for dust suppression. In this article we will discuss the more common ones and specifically how they work, where they work well, their limitations and safety and environmental issues.
The benefits of using dust control chemicals include improved dust suppression, enhanced safety for workers, better environmental protection, and significant cost savings through increased efficiency and equipment compatibility.
For all dust control chemicals, the better the road structure and condition the better the performance and this is particularly the case for longer term solutions.
Why Haul Road Dust Suppression
Haul Road Dust suppression is a vital process for industries such as mining and construction, where controlling dust is essential for both operational efficiency and environmental protection. Dust particles, if left unmanaged, can become airborne dust that creates poor visibility, increases the risk of accidents, affects respiratory health, and reduces air quality on site. Effective dust control solutions, including the use of dust suppression chemicals can significantly reduce road dust. By implementing dust suppression strategies, industries can create safer, more productive work environments with improved visibility on haul roads and reduce the impact of dust on surrounding communities and ecosystems.
Chloride Salts
Water attracting salts such as magnesium chloride and calcium chloride work suppress dust on unsealed roads by absorbing moisture out of the atmosphere, making the surface behave like it has been lightly watered. Their dust suppression performance is dependent on their ability to absorb moisture which is affected by the temperature and humidity (eg magnesium chloride starts to absorb moisture at 32% relative humidity).
Magnesium and Calcium Chloride are very effective in suppressing dust and can provide long terms dust suppression without the need for watering for months. They are also more tolerant than other dust suppression chemicals of the quality of the road surface due to their action.
In climates that are dry for long periods (ie low overnight humidity) the surface may require occasional light watering. Chloride salts are highly soluble and are easily leached out of the surface with over watering or significant rain events, particularly shortly after application. This makes their application unsuitable in areas with high or regular rainfall. Chloride salts also require a degree of clay type material in the surface to hold the salts.
Concentrated chloride salt solutions are very corrosive to steel, although some suppliers include a corrosive-inhibiting additive.
Care should be taken using the salts on ramps or declines because they can cause the road surface to become slippery when wet, particularly if there is a high fines content in the surface. Roads treated with chloride salts can also lose their structural strength if they become over wet due to the dissolving and leaching of the salt leaving voids which allow the penetration of water into the road surface.
Chloride salts can have environmental impacts in water ways or ground water if the salts migrate off site, but the risks are generally low if there is adequate buffer zone between the treated area and water ways.
Lignin Derivatives
Lignin is a bi-product of the wood pulping process and lignin derivatives are used in road dust suppression to bind the gravel and fines in the road surface together.
In dry conditions it improves the strength of the road surface and can be very effective for months, which helps reduce dust over a longer period. Due to the binding effect the better the road condition prior to application the better the product performs.
In very dry conditions lignin derivates (eg lignosulphonate) can become brittle so light watering may be required. Lignin derivates are highly soluble in water so they are easily leached from the road surface with heavy watering or rain. This solubility also makes the road slippery when wet which makes them unsuitable for use on ramps and declines. Like Chloride Salts, the dissolving and leaching of the Lignin when the roads become wet can cause the roads to lose structural strength.
There are generally no environmental impacts if adequate buffer zones are between treated areas and water ways.
Bitumen emulsions
Bitumen emulsions, including asphalt, are road-binding treatments that bind the road surface particles together to create a strong, hard wearing, sealed and waterproof surface.
Bitumen emulsions can provide long term, quality road surfaces that do not require watering and can require minimal maintenance. The quality of road structure combined with the type and frequency of traffic impacts their practicality and maintenance requirements.
The performance of bitumen emulsions is very dependent on the quality of underlying road structure. If there are too many fines in the surface the bitumen can form an unstable crust and fragment under traffic. If the road structure is not stable, then movement can cause cracks in the surface. If water is able penetrate through cracks or small holes, then it can quickly damage the unprotected road base causing holes which can have sharp edges that damage tyres, although an intact surface can help limit erosion and wear. Due to the lack of structure in many haul roads this means that bitumen emulsion surfaces can require ongoing maintenance.
Due to the environmental and OH&S requirements with these products they are typically applied and maintained by specialist personal. In a remote mining environment this and the maintenance requirement may require the bitumen emulsion supplier to maintain staff permanently on site.
Bitumen emulsions are petroleum-based products and can come from a range of sources some of which may be toxic. There are environmental risks with spills and leaching prior to the product 'curing'. The handling of the raw product typically requires specialist PPE to manage fumes and contact risks.
Polymers
Polymers work by binding particles in the road surface together when they dry. The strength of the polymer bonds and their ability to withstand environmental conditions varies between polymer types, polymer quality and application rate.
Polymers are cost effective and easy to and safe to use on mining haul roads and within mining operations. They can also deliver lower operational costs through reduce water use, maintenance and regrading. They are frequently added to mine water carts as part of mines ongoing watering program.
The limitations with most polymers are their short duration performance on haul roads due to the heavy vehicles continual breaking the polymer bonds so new bonding material needs to be regularly added.
The early polymers used for dust suppression were based on PVA and vinyl acrylic. These are readily available, cheap and easy to use. These are less frequently used for mine haul roads, but are still used in high concentrations for longer term dust suppression of light vehicle roads. Care must be taken with using vinyl acrylic in ongoing spray system as it can build up on nozzles and in pipes if not flushed after each use.
In the past 10 years gelling type polymers have been used on mine haul roads. They are used at low application rates (as low as 1:50,000) as water extenders to reduce watering. They are not used in high concentrations due to their gelling behaviour which makes applying at high concentrations impossible. The low volume of product required made them a cost-effective option to reduce water usage and lowering demand for water trucks. The gelling polymers require carefully diluted (added to running water) or they will gel. They can be problematic for ongoing applications with dosing system due to their gelling behaviour which can block pumps and nozzles.
New polymer products (eg DustWorx GX) have been released recently which have all the cost and performance benefits of the gelling polymers (reducing water usage by 50%) without the gelling behaviour making them ideal for automatic water truck dosing. These polymers can also be used at higher application rates making them suitable for longer term road dust suppression, although this is usually limited to light vehicle roads on mines. The polymers bond to the road surface particles in such a way that they remain effective under various weather and traffic conditions. Some of these (including DustWorx GX) also rebind when re-wet which results in a build up in performance. These new polymers have the advantages over other long term solutions in that they are environmentally safe, easy to apply and do not becoming slippery and dangerous in the wet.
All dust control chemicals work best on well-constructed and compacted roads. This is particularly the case for polymers where their performance is enhanced by good road compaction which is facilitated by regular heavy vehicle movements shortly after application. The performance of polymers is reduced on loose surfaces particularly those with loose gravel and where vehicles are turning as this increases the breaking of the polymer bonds. In high concentrations some polymers are slimy when in solution, but in general they do not cause road slipperiness when applied at the recommended application rates as they quickly bond to the road particles.
Polymers do not leach and are generally safe to use and safe for the environment with many considered biodegradable.
Surfactants / Wetting Agents
Surfactants and wetting agents act by reducing the surface tension of the water.
Mine haul roads can become very compacted which reduces the ability of water to penetrate the surface. Surfactants and wetting agents improve the waters ability to penetrate into the road surface. In addition surfactants help create smaller water droplets with greater surface area, allowing for more even distribution and improved dust suppression effectiveness. This has the effect of extending the time between watering.
Most surfactants are safe to use and safe for the environment with many biodegradable. Care does need with using surfactants with some ores as surfactants can impact processing that utilise flotation.
Surfactants are commonly used with polymers and other dust suppression chemicals to improve their penetration into the road surface.
Eco Friendly Options
As environmental awareness grows, eco-friendly dust suppression options are becoming increasingly important for industries seeking sustainable solutions. Dust Control Polymers such as DustWorx GX have been developed to provide long term dust control on haul roads and construction sites without the environmental drawbacks of traditional products. These environmentally friendly dust suppressants are designed to be non hazardous and biodegradable, making them suitable for a wide range of applications. By choosing eco friendly dust control chemicals, companies can effectively suppress dust while minimising their environmental footprint, ensuring compliance with environmental regulations and supporting broader sustainability goals. These solutions are not only safe for the environment but also cost effective, offering reliable performance across a range of sites and conditions, with lower water usage a benefit where water scarcity is a concern.
Cost Effective Haul Road Dust Control
For industries that require ongoing dust suppression, finding cost effective methods is crucial. Finding the most cost effective haul road dust control comes down to selecting the best solution for the specific application. And there is no one solution that is best for all applications. It is important to take into consideration the climate (eg chloride salts can be good in very low rainfall areas), the type of vehicles (eg 400 ton haul trucks require different solutions to 20 ton dump trucks), the road surface material (eg road surfaces high in clay are different to sandy surfaces), and available water on mine sites (eg water scarcity requires longer lasting dust control chemicals). By selecting the right dust control solution, companies can achieve reliable dust suppression while managing costs, supporting environmental responsibility and helping the mining industry lower long-term road management costs.
It is important to note that some dust control chemicals can actually result in cost savings through reduced water cart usage. See our DustWorx GX page for details.
Application and Performance
The effectiveness of dust suppression chemicals depends heavily on quality road preparation, proper application and ongoing performance monitoring. If a road is already damaged (ie rutted and loose dust on the surface) it is very difficult for a dust control chemical to work effectively. If a road is well prepared then the chemical only has to hold the surface together (and not bind the loose dust back into the road). For optimal performance, it is essential to follow the manufacturer's guidelines and adjust application rates for site-specific needs and road conditions. Proper application involves using the right amount of chemical and water in each application and at the correct frequency. Product longevity varies, with some treatments only reducing water cart frequency and some lasting months. It is important that the site has a champion who has the authority and knowledge to adust the application rate, frequency and water rate based on traffic, weather patterns and site performance to maximise dust control while using the chemical cost effectively.
One of the biggest causes of damage to haul roads and as a result the generation of dust is the over watering of roads. When roads are over watered they are softer and more easily damaged by heavy vehicles. This damage is one of the main causes of dust generation. For some dust control chemicals (eg Chloride Salts) over watering can significantly degrade their performance.
Traffic and weather will affect the road surface and the longevity of the dust suppressant, so regular maintenance and monitoring are necessary to ensure continued dust control. By tailoring the application to the unique conditions of each site, industries can maximise the benefits of dust suppression chemicals and maintain safe, stable road surfaces, while smart dosing units can support monitoring and application control where automated dosing is available.
Benefits of Effective Dust Control
Implementing effective dust control measures offers a wide range of benefits for both operations and the environment. By suppressing airborne dust that can create safety and health issues across mining operations, dust suppression improves air quality, improves visibility, and reduces the risk of incidents for workers and nearby communities. Cost effective and eco friendly dust control solutions also help protect the environment by minimising dust emissions and limiting broader impacts on nearby communities, groundwater and surrounding ecosystems. Additionally, maintaining cleaner, safer sites can lead to increased revenue by reducing downtime, improving equipment longevity, reducing wear on equipment,and supporting regulatory compliance. Ultimately, investing in dust suppression not only safeguards health and safety but also delivers long-term environmental and operational advantages.
If you have a particular dust control application you would like to discuss or would like more information then please call us on +61 2 6062 3300 or send an email to sales@wetearth.com.au.
Frequently Asked Questions
What is the best chemical for dust suppression on mine haul roads?
The best chemical for haul roads depends on whether the mine wants something that will be a single long term application or a product that will reduce water cart usage and reduce dust. Polymers such as DustWorx GX can reduce haul road dust and be cost neutral through reduced water cart fuel usage. For longer term application in areas with low rainfall then chloride salts or lignin base products can be effective. For long term application in higher rainfall occurs then polymers such as Shield AWR or DustWorx GX are the best option, but may regular top up applications.
Which is better for haul roads: polymers, lignosulfonates or magnesium chloride?
The best product depends on the site requirements and the conditions. Polymers are usually best to reduce water cart usage and haul road dust and are very cost effective. Lignosulfonates and magnesium chloride are generally used for longer term applications, but their performance can be degraded or lost with rainfall and road grading.
How much can dust suppression chemicals reduce water cart usage?
Dust suppression chemicals such as chloride salt, lignin and bitumen based products can eliminate the requirement to use water carts to suppress road dust. Polymer dust control chemicals typically reduce the requirement to water a haul road by 50% initially with performance increasing over time as the polymer build up in the road surface.
How long do chemical dust suppressants last on heavily trafficked mine haul roads?
How long a chemical will suppress dust on a haul road is dependant on the frequency and type of traffic, the road structure, road material and the climate. Quality polymers such as DustWorx GX typically double the time required between watering. In the correct conditions magnesium chloride can suppress dust for in excess of 6 months, although typically grading of the roads limit their duration.
Which dust suppression chemicals work best in hot, dry conditions?
In hot dry conditions with very low chance of heavy rain the chloride salts such as Magnesium Chloride are very effective.
Are chemical dust suppressants environmentally safe?
Most chemical dust suppressants are safe when used as specified. Chloride salts can leach from the surface and bitumen emulsions can be an issue in their concentrated form. Generally the polymers are the safest products as they stay bound to the road particles and many are biodegradable. Always review the SDS of the dust suppressant to determine any safety or environmental risks.
Which dust suppressant is most cost-effective for large mining operations?
The polymer dust suppressants such as DustWorx GX are very cost-effective and in many cases can be cost saving with their reduction in water truck usage. The longer term products such as magnesium chloride are high cost, but in the right conditions can eliminate water cart usage for a period of time saving significant costs. Polymers can be used for longer term applications, but for this you require much more product than. For example DustWorx GX can use used at 1:5,000 to reduce watering requirement by 50%. If you want it to last a 8hr shift we recommend 1:200.
Can dust suppression chemicals eliminate the need for water carts?
Technically dust suppression chemicals can eliminate the need for water carts, but on mine haul roads this is not practical as even the longer term products require reapplication - at the least because the roads require grading.
What are the disadvantages of chemical dust suppression on haul roads?
Different dust suppression chemicals has its own disadvantages. Lignosulfonates and magnesium chloride can damage the surface of the road when they leach out. Magnesium chloride can make the road surface slippery when wet. The gelling polymers can block dosing pumps and water truck pumps and nozzles.
Which companies supply haul road dust suppression chemicals in Australia?
The companies which are best known for haul road dust suppression chemicals are Dustex (lignosulfonates), Dustaside (bituminous emulsion), Rainstorm (magnesium chloride) and Wet Earth (polymers).
Can dust suppression chemicals be applied using existing mine water carts?
Generally only polymer and lignin based dust suppression chemicals can be applied using existing mine water carts. Bitumen and magnesium chloride are usually applied in dedicated equipment due to their coating and corrosive properties.
Does a haul road need grading or compaction before applying dust suppressants?
All dust suppression chemicals will perform better with a freshly graded and compacted roads. Most dust suppressants (with the exception of the chloride salts) work by binding the surface of the road together preventing the fines working their way to the surface. If there are already fines on the surface then the chemical needs to try to bind that into the road surface first - wasting chemical. Roads that are freshly graded have less variation in the surface which the heavy haul trucks can break off causing exposed untreated areas. A road that is loose (not compacted) will be more prone to rutting and creating the variations in the surface. For longer term dust control solutions it is usually more important for the roads to be graded and compacted prior to application to maximise the time before reapplication.
Can dust suppression chemical dosing be automated on mine water trucks?
Typical chemical dosing is undertaken at the water stand pipe. Wet Earth supplies solar powered stand pipe dosing systems for its DustWorx GX dust suppressant. These can be triggered by remote in the water truck or by the starting of the standpipe water flow. This includes remote reporting and notifications via web or phone app.
Why do chemical dust suppressants sometimes fail to work on mine haul roads?
Dust suppression chemicals can fail to work on mine haul roads for many reasons. Some of the more common reasons include sites having the wrong expectations (over promising by supplier), uneven dosing / mixing, weather events or operator error (rain or water cart spraying after application of lignosulfonates or magnesium chloride).