MechChem Africa November-December 2024

⎪ Minerals processing and materials handling ⎪

need to clean a remote dust-collection site.

Plastics Group of America handles calcium carbonate Calcium carbonate (CaCO 3 ) is a naturally occurring mineral common in such diverse products as cement, antacids, calcium supple ments, cosmetics and polymer formulations. It also functions as a filler and pigment in the pulp and paper industry and reduces acidity and impurities in water and sewage treat ment plants. Powdered CaCO 3 is a non-free flowing material with a bulk density of 443-734 kg/m 3 that readily packs and cakes with certain grades and particle sizes. It can also resist gravity flow, adhere to hopper sur faces, build up in mechanical conveying lines, and blind filter media in pneumatic conveying systems. Plastics Group of America (PGA) com pounds reinforced plastics to create custom resins to suit the needs of their customer base, with CaCO 3 being one of the additives. When the material is metered into downstream processes to manufacture their products, an automated bulk bag discharging system saves operators from opening multiple handheld sacks, while cutting material costs and improv ing downstream fill-weight accuracy. Flexicon provided a solution that worked with the difficult CaCO 3 material in a limited headroom facility by installing a system that maintains material flow while reducing manual labour. The result is a twin-screw compound ing line operating on a single floor eliminating the need for multi-level platforms, something PGA wanted to avoid. The company uses a pair of Flexicon BULK-OUT ® model BFC dischargers. Each efficiently empties bulk bags into a hopper at its base, using FLOW-FLEXER ® bag activa tors to keep the CaCO 3 flowing out of the bag without manual intervention. The flex ible screw conveyor transfers the powder through an inclined outer tube to a feeder on the compounding line. Both dischargers use a BEV-CON™ flexible screw conveyor with optimised auger design for handling materials such as powdered CaCO 3 that packs, cakes, bridges or otherwise resists flow, without binding or jamming. The motion of the screw conveyor is governed by a loss-in-weight control system on the feeder. This signals the conveyor to start or stop the feeder hopper when it reaches preset weight levels. Each flexible screw conveyor handles 22.7 to 907 kg per hour of additives, depending on the material being compounded and changes material once or twice a day, with a typical run lasting 18 hours.

FLOW-FLEXER ® bag activators that raise and lower opposite bottom edges of the bag into a steep 'V' shape, directing material towards the bag outlet. As carbon black flows through the dust-tight connection to the hopper, displaced air and dust are contained by a Flexicon BAG VAC ® dust collector mounted on the discharg er frame. Dust accumulated on the cartridge filters of the Bag-Vac is blasted by air jets on a timed cycle, returning it to the hopper. In combination with the Tele-Tube, the Bag-Vac creates a sealed system between the bulk bag and the conveyor. The vacuum feature can also be applied to collapse empty bags prior to tie off and removal, preventing fine dust particles from escaping during this process. The hopper houses an inlet adaptor for a flexible screw conveyor comprised of a poly mer tube with a BEV-CON™ flexible screw conveyor featuring specialised geometry specially designed to minimise compression of the material. Kirkhill reports that the use of bulk bags has simplified the handling of carbon black, while the air-tight system has yielded a cleaner and safer processing environment. The results are improved efficiencies and reduced opera tional costs. Test for best results For the most effective solution to problems posed by non-free-flowing materials, a bulk handling equipment manufacturer offering a comprehensive test laboratory should test run the customer's actual material on full-size equipment that can simulate the process in question, while documenting the performance based on the most efficient combination of equipment and accessories. Since 1999, Flexicon’s South African en gineering and manufacturing headquarters has provided localised services and solutions for bulk material handling of food, chemical, and other industrial processing throughout the region. www.flexicon.co.za At Ameron International, bags of TiO 2 are emptied into this bag dump station, which includes dust collection and a support tray for opening bags.

black amorphous powder or finely divided pellets. Insoluble in water and solvents, it has a high surface-area-to-volume ratio and a bulk density of 300-570 kg/m 3 depending on particle size and packing. It serves as a black pigment for inks and paints, a reinforcing filler in tyres and other rubber products, and as an agent to adjust conductive properties in the manufacture of plastics, coatings, cables and highly-engi neered specialty parts for the aerospace and defence industries. Fine carbon black particles tend to cake, pack and/or fluidise. As a result, the fines tend to form deposits in conveying lines, which im pedes flow. Also, airborne dust poses a safety concern to personnel, and can penetrate operating equipment, adversely affecting lubrication and causing short circuits. Flow promotion and containment of car bon black particles is therefore essential when conveying this material. For bulk bags, an auto mated, fully enclosed discharging system with flow promotion devices can transfer carbon black to downstream processes, dust-free. Kirkhill, a manufacturer of specialty elastomer parts for the aerospace industry, reduced inventory and improved plant cleanliness when it switched from carbon black received from railcars and stored in silos, to receiving it in bulk bags. The company installed a BULK OUT ® bulk bag discharging system comprised of a discharger frame, enclosed hopper and integral flexible screw conveyor from Flexicon. The discharger includes dust-tight connec tions to fully contain carbon black until its final addition to the mixer. The bag spout interface forms a high-integrity seal with a SPOUT LOCK ® clamp ring that clamps the bag spout to a telescoping TELE-TUBE ® , which is raised to allow a dust-tight connection, then lowered to elongate the bag, facilitating material flow into the bag spout. Additional flow promotion is achieved by At Kirkhill, the bulk bag discharger, hopper and flexible screw conveyor fully contains carbon black pellets, preventing dust from entering the plant environment.

Kirkhill Inc handles Carbon black Carbon black can take the form of an intensely

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