Three new technologies from a global manufacturer of conveyor belt cleaning systems help overcome problems faced by operators in bulk material handling.

Controlling dust, carryback and material accumulation is an essential element of bulk material handling by conveyor, as well as bulk storage. Every tonne of material lost in transport equates to reduced revenue, and fugitive material can pile under and around equipment, making it hard to remove and presenting safety risks in the work area. It can also act as an abrasive, seriously reducing equipment life, while increasing the need for maintenance and extending shutdown periods. If accumulation gets bad enough in chutes and storage vessels, it can force unplanned system outages and cause major disruptions in production to clear blockages.

Innovative belt cleaner design

Martin Engineering now offers a revolutionary belt cleaner design that can remove even the most difficult carryback. Unlike conventional belt cleaners that are mounted at a 90 degree angle to the belt, the CleanScrape Cleaner is installed diagonally across the discharge pulley, forming a three-dimensional curve beneath the discharge area that conforms to the pulley’s shape.

The unique design incorporates a matrix of tungsten carbide scrapers and is tensioned lightly against the belt to prevent damage to the belt or splices. Despite extremely low contact pressure between belt and cleaner, it has been shown to remove as much as 95% of potential carryback material. The novel approach has been so effective that in many operations, previously crucial secondary belt cleaners have become unnecessary, saving further on belt cleaning costs and maintenance time.

The innovative belt cleaning system received the Australian Bulk Handling Award in the “Innovative Technology” category for its design and potential benefits, which include low belt wear, extended service life, reduced maintenance and improved safety, ultimately delivering lower cost of ownership. With its compact size, the design is an excellent solution for areas with restricted space. It can be located either inside or outside of the transfer chute, and the straightforward installation typically requires less than two hours.

“Smart” air cannons

Air cannons have proven to be an effective flow aid over 40+ years of use in cement manufacturing, coal and ash handling, rock crushing and other applications. Also known as air blasters, the technology helps improve throughput and reduce material build-up with a powerful discharge of air, dislodging accumulation that impacts process efficiency and raises maintenance expenses.

There have been a number of improvements to air cannon designs since it became a commercially viable technology in the early 1970s, which have enhanced cleaning performance, energy efficiency and safety. Among the upgrades is a high-speed valve design that can be mounted on a smaller air reservoir, delivering higher discharge forces than less efficient valves on larger tanks. The new generation of valves produces about twice the blast force output of the designs introduced just a decade ago, allowing users to save energy by using about half the compressed air volume.

Another energy-saving development is the piston return reservoir. During the air cannon’s firing sequence, the pressure in the return reservoir approaches that of the tank, but the fast-acting valve closes when about 50% of the tank’s original pressure remains. The peak force output remains the same, but air consumption is dramatically reduced, easing the demand on plant air supply and reducing cost.

Air cannons have also become safer in recent years, with new positive-firing valves that respond to an air pressure surge delivered by a solenoid valve. In order for the cannon to fire, a positive signal must be received. Unlike negative pressure-firing designs, a cannon equipped with this new type of valve will not discharge accidentally in response to a drop in pressure, so an interruption in air supply or broken line cannot trigger it.

There has also been significant advancement in nozzle technology for air cannons over the last few years, such as a 360º retractable design that extends into the material stream only during the firing cycle to protect itself from extreme temperatures and abrasion. This innovative design solves two common industry problems: effectively dislodging accumulations in hard-to-reach areas without shutdown or manual labour, while significantly extending nozzle life. Further, the retractable nozzle can be serviced from outside the vessel, reducing service time and risk of injury.

The benefits include significantly reduced damage to refractory brick and drastically shorter nozzle service times. By avoiding the need for confined space entry, the new design has eliminated much of the potential risk involved with the changeout process. It also allows system operators to add air cannons to an existing process during a brief shutdown, without completely cooling down the entire system to allow entry into the interior of a vessel.

Cleaner air, smaller footprint

While central “baghouse” air cleaning systems have been in use for decades, they present a number of challenges, not the least of which is their cost. They typically require extensive ducting systems that can suffer from dust build-up, and the systems tend to use large amounts of power. In addition, filtered dust requires a method of recirculation or disposal.

An alternative to the central collector is the integrated air cleaner system, which contains a suction blower, filtering elements and a filter cleaning system. Instead of a centrally located unit connected to dust generation points via ductwork, this type of cleaner is incorporated into the dust generation point itself. The particles are not extracted, but are instead collected within the enclosure and periodically discharged back into the material stream.

Unlike central systems, the integrated approach employs a series of smaller, independently operating units, one at each dust generation point. This decentralised approach allows the air cleaners to be incorporated into a maintenance cycle, and no single unit requires a complete system outage for maintenance. The nature of the integrated air cleaner design eliminates many of the disadvantages of a central dust collector, often while providing superior effectiveness. Among recent advancements in air cleaning technology is a new integrated design that features improved filtering and a smaller footprint, helping bulk material handlers minimise airborne dust at belt conveyor loading and transfer points. The Martin® Insertable Air Cleaner is an automatic, self-cleaning unit designed to remove dust from the air in conveyor loading and transfer points, silo vents, bucket elevators and screens.

The collector design employs filter elements that are approximately one-eighth the size of filter envelopes in preceding systems. The smaller filter elements allow a significant reduction in the dust collector’s “footprint,” so it can be placed in locations where tight quarters complicate the installation of other systems. The mesh-like material filters better and lasts longer – while consuming less energy – than conventional filter bags. The new filters also allow a reduction in fan size to move air through the elements, helping to reduce the overall power consumption of the collection system.

Martin Engineering supplies bulk material handling equipment around the world for a wide variety of applications, including mining and coal handling, biomass, cement/clinker, rock/aggregate and other materials. Founded in 1944, the firm is headquartered in Neponset, IL, offering manufacturing, sales and service from factory-owned business units in Brazil, China, France, Germany, Indonesia, Mexico, South Africa, Turkey, India, the UK, Japan, Russia, Peru and under exclusive license with ESS Australia.

Global representatives for Martin Engineering can be found at www.martin-eng.com/rep-finder