• Publication Date: 07/01/2020
  • Organization(s):
  • Article Type: Case Histories
  • Subjects: Mechanical conveying, Screening and classifying

Case History

Performance company uses a material handling system to reset the stage before each performance.

Cirque du Soleil, an entertainment and circus company, is known worldwide for its acrobatic theatrics and technically innovative staging. For example, the company’s production of KÀ at the MGM Grand in Las Vegas, NV, uses moving platforms and granulated cork to stage a beach scene on the sand cliff deck.

Cast members dance in the faux sand until the platform tilts slowly forward and the cork, performers, and props are swept off stage, seemingly into the abyss. In reality, the performers and props land in a circus net, while 250 cubic feet of granulated cork passes through the net and into containers 50 feet below.

Because the performers jump, slide, and plunge their faces into the cork, Cirque du Soleil cleans and conditions the material before each show. “We do everything in our power to ensure our acrobats are safe,” says Aaron Bush, the daytime lead carpenter at KÀ.

To achieve the visual effects while ensuring the safety of its performers, Cirque du Soleil had to begin processing bulk materials, a process most people in the entertainment industry are unfamiliar with. The company needed equipment to transport and clean large volumes of cork for reuse. To make its vision a reality, Cirque du Soleil turned to Flexicon, a bulk solids handling equipment supplier and manufacturer, for equipment engineering support.

Cleaning and reusing cork

The company requires one batch of cork for two nightly performances. Cleaning the batches requires a team of three: one in the pit, another at the cork cleaning system, and a third at the collection area one floor below.

From the pit, cork granules, together with cork dust and any foreign objects, are pneumatically conveyed to a large surge hopper positioned above the cork cleaning system. As the cork discharges via gravity from the upper hopper through a downspout, the material passes through a permanent magnet that catches any bobby pins, nuts, bolts, or other ferrous material that might have contaminated the cork.

The material then flows into the 5-cubic-foot surge hopper of a 10-foot-long flexible screw conveyor. The conveyor has a shaftless screw that rotates within a 4.5-inch polymer tube inclined at 45 degrees, which serves to both elevate the material and feed it volumetrically into a vibratory classifier. The amount of material continuously fed into the classifier can be fine-tuned by adjusting the conveyor screw’s rpm.

Once in the classifier, particles vibrate across the equipment’s perforated deck, and correctly sized particles descend through the perforations and through 6-inch-­diameter flexible downspouting. The downspouting empties the cork on the floor below where several nozzles mist the cork with distilled water. Oversize foreign material continues across the classifier’s perforated deck and discharges through a downspout into a receptacle.

“If the cork is too dry, it becomes really dusty and can leave a film on the deck,” says Bush. “That would become a hazard to our performers, and we don’t want people breathing airborne dust.” Samples are checked using a grain hygrometer, and a bleach disinfectant is sometimes applied to prevent mold. “We like to keep the cork between 68 and 72 percent relative humidity,” says Bush.

Cork dust is separated by an upward-flowing airstream produced by a fan below the classifier’s perforated deck and a dust filter-­receiver above the deck. Cork dust collected on the outer surfaces of the receiver’s filter material is periodically pulse-cleaned using short blasts of compressed air, causing the dust to collect in the lower section of the cylindrical dust collector’s enclosure. The dust is emptied through an 8-inch manual gate valve at the enclosure’s outlet.

A low-maintenance, effective solution

The cleaned and conditioned cork is staged in six mobile bins that are emptied onto the sand cliff deck for both nightly performances.

The machine is inspected and cleaned after each use, and the entire system is dismantled and cleaned annually. The filter-receiver’s seven bag filters slip over steel cages, allowing for easy removal. When cleaning is required, the bag filters are simply laundered in a washing machine.

For a performance company with minimal bulk solids handling experience, the equipment needed to not just work but work with minimal operator interaction. The screw conveyor requires minimal maintenance outside of removing bits of string, strands of hair, or other fibrous material, which can sometimes tangle up where the rotating screw attaches to the drive motor’s shaft. This area has a window to allow users to see any potential problems and provide easy access to cut away and remove material with a knife.

“The system works exactly as designed,” Bush says. “We’re recycling a good 80 percent of the cork. Outside of standard maintenance, we haven’t had to do anything.”


For further reading

Find more information on this topic in articles listed under “Mechanical conveying” and “Screening and classifying” in the article archive.

Flexicon • Bethlehem, PA
610-814-2400 • www.flexicon.com

Copyright CSC Publishing Inc.

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