Eliminating dust in conveyor systems

The importance of eliminating dust at special sections of conveyor belt systems and at transfer points cannot be reiterated enough. All measures taken for this purpose serve to protect workers and surrounding communities, to keep the production environment clean and often to provide explosion protection.

“Without an efficient dust control system, there is a greater risk of explosions, while spillage on the floor is wasteful and dangerous. A dust elimination system also improves visibility and enhances a safe working environment. In addition, it eliminates the need for a costly extraction system and because there is no spillage, there is no need for extensive cleaning operations,” he says.

Common issues

According to Mouritzen, mine and quarry managers are therefore constantly seeking solutions to deal with dust and spillage problems at the transfer points of conveyor systems. The risk of explosions caused by dust emissions on conveyor belts is an ongoing issue.

Although conventional dust prevention side-seals do reduce conveyor problems in the short term, these components quickly deteriorate as a result of friction and can also damage the belt of the conveyor system during extended periods of use.

“Conventional skirting is pressed against a conveyor belt to keep dust and material in the middle of the belt, but after a certain period, wear of the skirting and belt can be so severe that material and dust escapes,” says Mouritzen. “Material spillage at transfer points needs to be removed and regular maintenance of belt skirting and transfer points is essential.”

For optimum performance of a conveyor system, he adds, it is critical that the belt always runs straight on the conveyor, without sideways movement. Scrapetec’s new PrimeTracker belt tracker has been designed to automatically guide a conveyor belt back into the correct straight-line position to prevent costly downtime and component replacement.

The solution

ScrapeTec and BLT WORLD experts have developed a new dust control system that is proving to be highly effective – not only for preventing dust formation and material spill, but also for minimising the risk of explosion at critical sections along the conveyor route and transfer points, and for more efficient belt-cleaning.

Apart from the cost-saving benefit, DustScrape and AirScrape dust control systems are said to be highly effective in minimising exposure of workers to environmental pollution, which is a major problem in dry bulk handling, caused by fugitive dust.

The success of the combination of the DustScrape and contact-free AirScrape conveyor belt skirting systems is an effective energy-free dust control system. This compact and easy-to-install skirting adheres with most new dust-prevention guides to prevent health and safety issues on site.

Studies have shown that even five years after installation and with continuous use in harsh conditions, the AirScrape system shows hardly any signs of wear.

“This advanced system minimises product loss by effectively preventing material from escaping into the surrounding environment. As a result, users benefit from substantial energy savings, housekeeping and maintenance costs, without the need for collection of material spills,” says Mouritzen. “At a recent installation, BLT WORLD solved many production problems for a customer who was losing almost 5% of material on conveyor belts, as a result of dust and material spill.”

Solutions in detail

DustScrape consists of a durable filtering cloth that is installed above the conveyor belt to retain dust particles created by conveyed materials, while remaining permeable to circulating air. The long-lasting filter cloth, with cleaning and dust-releasing properties, is available in different qualities, including anti-static features, for specific applications – for example, in sugar processing or underground mining. The dust retaining filter cloth, which is manufactured in rolls, can be extended to any required length and is suitable for any conveyor belt width.

The DustScrape dust emission prevention system comprises a filter cloth, support arches and skirts, arms to hold the system above the belt and a rubber curtain to eliminate further dust development – all sized to specific requirements. This system is easy to install and can be retrofitted to existing conveyors for continuous operation and for extended periods.

The contact-free AirScrape conveyor belt skirting system is a highly effective side seal that is installed just above (1 mm) the belt surface and the stainless steel blades create a venturi effect which sucks fugitive dust and material back into the material flow on the belt.. Because the system hovers freely above the conveyor belt, skirt friction and belt damage are eliminated and service life of every component of the conveyor is extended.

The durable system consists of non-flammable and anti-static polyurethane materials and blades made from stainless steel. FDA-approved materials are also available for specific conveyor handling applications.

The recently launched SureSupport system works in conjunction with DustScrape and AirScrape to deliver support and stability to the belt at transfer points. Other advantages of this system include quick and simple installation, as well as reduced maintenance time and costs.

The TailScrape system enhances performance of the AirScrape, by sealing the transfer tail in the rear area and also works according to the Venturi concept, to prevent dust generation and material spills. The intelligent blade structure on the underside of the system creates negative pressure in the conveying area, preventing the escape of materials. Dust is kept in the material flow by air intake.

The SpeedScrape secondary belt cleaner design is based on the inclined and staggered positioning of Tungsten blades, which increases the scraping surface to as much as 150% of the conveyor belt width. This high-performance system allows scraped material to be easily discharged.

“In the range of ScrapeTec conveyor components is also the PrimeTracker belt tracker, which eliminates other problems associated with conveyor belt systems, including misalignment, abrasion and belt damage,” says Mouritzen. “The PrimeTracker ensures the belt is constantly in the correct position during operation, thus eliminating problems with belt mistracking, while the Airscrape efficiently controls dust, prevents material spill and minimises explosion risks.”

An advantage of this device is that it operates in the idling position at all times, unless there is sideways movement of the belt. The system corrects misalignment immediately, by guiding the belt back into the correct position, with no damage or abrasion to the belt or tracker. This is unlike conventional belt trackers that slide over the belt surface causing possible abrasion and belt damage. Conventional belt trackers, with tapered edges, never idle and are always in a braking mode.

“Of note is the cylindrical shape and pivot bush that allow this belt tracker to swing and tilt during operation and to always be in full contact with the belt. Added to this, the Scrapetec PrimeTracker has the same peripheral speed over the entire surface of the belt, where traditional crowned rollers have different speeds at the centre and edges of the system,” explains Mouritzen.

Other advantages include easy installation, low maintenance requirements and protection of belt edges and structure of the conveyor belt. A strong corrugated EPDM (ethylene propylene diene terpolymer) rubber hose protects the system from dust and sand, while the rubber pivot offers soft suspension of the tracker shaft, ensuring extended service life of the system. The system can be installed in front of every return pulley, above and below the belt.

Correct installation

Correct installation of suitable dust suppression equipment ensures cost efficiency, optimum performance and safety, reduced risk of breakdown and extended service life of the conveyor system.

“In close co-operation with ScrapeTec experts, BLT WORLD provides an assessment and solutions service to customers, for planning and implementing projects. A technical advisory and support service enhances performance of every ScrapeTec system,” concludes Mouritzen.