Filtering Out The Dangers Of Dust

Hayley Everett

Hayley Everett explores how air filtration systems can protect both operator and equipment

Coal, iron ore and other raw materials relied upon by many of the world’s industries require extensive mining before they can be processed further, and as demand for these materials has continued to rise, the mining sector has seen considerable growth. With this, the industry has, in turn, faced mounting challenges in improving its working conditions.

From asbestos to silica, contaminants can enter the cabins of mining vehicles such as haul trucks, wheel loaders and bulldozers through air vents, door seals or via vehicle operators themselves.

“Mining by its very nature generates large volumes of respirable dust emissions, many extremely dangerous due to their small size and composition,” explains Stephen Gledhill at Freudenberg Filtration Technologies, a developer of specialist air and liquid filtration systems. “Asbestos, silica, coal and diesel particulate are some of the primary health concerns.”

Alongside posing severe health issues, Gledhill adds that contaminated air can damage mining vehicles and their crucial components, leading to premature mechanical and electrical breakdowns.

“Ingress of dust into mining vehicle electrical enclosures causes premature equipment failure, fire risks and requires substantial regular maintenance to ensure safety and optimal equipment operation.”

As such, the development of increasingly sophisticated filtration technologies is paramount to reducing airborne respirable contaminants and CO2 levels in mining cabins. One such technology developed by Freudenberg Filtration Technologies is the firm’s SAFEair (security against fine elements) filtration system, which is designed to protect operator health and the overall functionality of mining vehicles.

The technology recently secured ISO 23875 compliance for safe heavy equipment cabins due to its ability to sufficiently reduce airborne contaminants and CO2 levels in mining vehicles.

“SAFEair is a purpose-built air handling system for mining vehicles, designed to protect operators and equipment from dangerous mining dusts,” Gledhill says. “Dust in vehicles is a huge health issue and an enormous cost to miners globally, both above and below ground.”

According to Gledhill, mining vehicles have not been particularly well-protected from the dangers of dust ingress in the past. Many vehicles traditionally used simple on-road air conditioning systems with either little or no filtration efficiency that are not suited to small diameter mining dusts.

“Often systems recirculate air within the cabin with no filtration – any dust or smoke brought in through opening doors or on clothes or boots is continually recirculated through the cabin with human lungs the only method of removal,” he explains. “Filtered pressurisers are sometimes added as a separate afterthought system, but these do nothing for recirculated air, often use low-grade filters and generally push against a dead end with no allowance for air to actually be exchanged.”

This is often compounded by operators sealing cabins tight to promote higher cabin pressure, as CO2 can become a real issue in vehicle cabins if air exchange is not enabled. CO2 levels can quickly rise to dangerous heights, contributing to fatigue, headaches, nausea and, subsequently, accidents.

The SAFEair filtration technology is designed to alleviate the issues above by using a multi-stage filtration process that meets the international norm ISO 23875 for cabin pressurisation and filtration. The standard requires that fresh air supply and air recirculation must keep concentrations of particulate matter below 25µg per m3, while maintaining pressurisation and CO2 limits. Pressurisation inside operator enclosures must be between 20Pa and 200Pa, while CO2 concentrations must not exceed the ambient CO2 plus 400 parts per million (ppm).

How Does The Technology Work?

The system uses a multi-stage filtration process comprised of two pre-cleaning filters and two high-flow HEPA filters for particle separation. The two pre-cleaning elements protect the HEPA filters from heavy dust exposure to prolong filter life.

The system works by first passing air through a cyclonic dust ejection system that filters out heavy dust particles and then through a second pre-cleaning filter to remove coarse dust particles. Two stages of HEPA filters then eliminate 99.995% of sub-micron particles to achieve full cabin air exchange within 20 seconds.

As well as filtering outside air entering the cabin, the SAFEair product also draws and filters air from within the cabin to ensure a dust-free environment. The HEPA-filtered air then re-enters the vehicle cabin via the air vents into the operators’ breathing zone while also allowing some air to escape the system for fresh air exchange. Ultimately, the system provides hospital-grade air at ambient CO2 levels that are continuously monitored both inside the vehicle and remotely via telemetry.

“The mining industry has recognised the issues of dust ingress and recently implemented the new standard for vehicular cabin air quality, ISO 23875,” continues Gledhill. “The key benefits of SAFEair listed above are directly called for by the standard to ensure high-level filtration of both outside and recirculated air, high cabin pressure, fast removal of residual dust within the cabin and fresh air exchange for CO2 abatement.”

According to Gledhill the system offers advantages that he believes cannot be found on other comparative OEM or aftermarket filtration systems. “In addition to overall system performance, controls and telemetry set SAFEair apart,” he says. “System condition can be monitored directly on dash displays or remotely via wireless, satellite or 4G to any device, including mobile apps. Mining sites find this to be an amazing predictive maintenance and OHS tool, the system displaying and transmitting data such as temperatures, pressures, gas and dust levels, location and full air conditioning parameters, to name a few. Likewise, the system can be adjusted and maintained remotely, often eliminating a requirement for live works.”

Alongside improving the safety conditions for the operators inside the cabin, the system also helps to protect the vehicles and their components from mining dust. For instance, the HEPA level filtration of recirculated air protects air conditioning components such as fans and evaporative coils from dust-related damage. In many cases, this can lead to considerably reduced maintenance costs that ultimately outweigh the upfront cost of installing and upkeeping the system.

“A lot of work we do is on vehicles without operators, with our systems being used to protect electrical control units on autonomous vehicles,” Gledhill explains. “A recent example was the fit out of over 200 CAT 793 haul trucks that were having major maintenance and cost concerns through dust fouling their autonomous controls. Dust-related maintenance drops to zero with SAFEair.”

This not only has positive ramifications for maintenance costs but also helps to improve on-site safety through ensuring the vehicles’ autonomous controls are functioning correctly.

He adds, “High voltage cabinets on electric drive trucks is also a major focus for us, and we are fitting out many models, including those of Komatsu and Terex. Again, the relatively minimal cost far outweighing the downtime cost encountered by operators of these machines due to dust ingress.”

In terms of compatibility, Freudenberg has a large and continually expanding database covering most major OEM equipment within the mining sector, Gledhill says. As a result, the system is compatible with equipment ranging from light vehicles and underground equipment to the largest dozers, haul trucks, draglines and excavators.