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July 2020 / 23 conveyor requires minimal main- tenance outside of removing bits of string, strands of hair, or other fibrous material, which can some- times 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 recy- cling a good 80 percent of the cork. Outside of standard maintenance, we haven't had to do anything." PBE For further reading Find more information on this topic in articles listed under "Mechan- ical conveying" and "Screening and classifying" in Powder and Bulk Engineering's article index in the December 2019 issue or the article archive on PBE's website, www.powderbulk.com. Flexicon Bethlehem, PA 610-814-2400 www.flexicon.com perforated deck and a dust filter- receiver above the deck. Cork dust collected on the outer surfaces of the receiver's filter material is peri- odically pulse-cleaned using short blasts of compressed air, causing the dust to collect in the lower sec- tion of the cylindrical dust collec- tor'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-receiv- er'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 expe- rience, the equipment needed to not just work but work with mini- mal operator interaction. The screw cally 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 per- forated deck, and correctly sized particles descend through the perfo- rations and through 6-inch- diameter flexible downspouting. The down- spouting empties the cork on the floor below where several nozzles mist the cork with distilled water. Oversize foreign material contin- ues 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 per- cent relative humidity," says Bush. Cork dust is separated by an upward-flowing airstream pro- duced by a fan below the classifier's A shaftless screw rotating within an enclosed tube moves the material into a vibratory classifier. Cirque du Soleil's beach scene uses faux sand made out of cork granules that are automatically cleaned, conditioned, and reused for each performance.