materials handling | Technology
Above: The R-PRO conveying system from Conair transports material at slower speeds to cut wear and dust generation
experience in a variety of industries means that we can convey, load, unload, weigh, feed and process virtually any bulk solid material, which is proving invaluable in compounding where we need to handle a wide range of different materials accurately and safely.” One recent example was at the Netherlands-based
compounding facility of Trinseo, where Flexicon says that an investment in bulk bag dischargers and flexible screw conveyors is increasing productivity, worker safety and plant cleanliness. The company runs eight compounding lines in a 5,000m2
close concentrically around the spout, preventing product leakage. The clean side of the bag spout attaches to the clean side of the discharger by means of a clamp ring, which is mounted on the top of a telescop- ing tube that maintains constant downward tension on the bag as it empties and elongates, promoting material flow through the bag spout. Pneumatically-actuated flow-promotion devices raise and lower opposite bottom sides of the bag, forming a ‘V’ shape to promote total discharge into the hopper. The hopper is vented to a dust collector that vacuums displaced air and dust from the sealed system as talc or impact modifier discharges from the bag, improving plant cleanliness. As material enters the hopper, a flexible screw
plant and installed two
Right: Bulk bag dischargers and flexible screw
conveyors from Flexicon in
operation at a Trinseo
compounding facility in the Netherlands
Bulk-Out BFC-X bulk bag discharging systems with integral flexible screw conveyors from Flexicon. One system unloads and conveys talc used to improve the mechanical properties of polypropylene compounds; the other unloads and transports an impact modifier in polycarbonate/ABS formulations. “The bulk bag dischargers replace manual unloading,” says Ron Drabbe, Senior Improvement Specialist at Trinseo. “The equipment promotes complete evacuation of bulk bags and conveying of material to blending hoppers on compounding extruders. Each bulk bag weighs 600kg (1,320lb). Unloading a bag previously required three workers. Two would mechanically hoist a bag above a hopper while a third, working from a platform on top of the hopper, connected the bag to a discharge unit and dislodged trapped residue by hand. Non-free- flowing talc was especially prone to lodging in corners of the bags. Apart from the risk of injury in handling bulk bags and climbing up and down platforms, unloading generated dust, which settled on the plant floor.” Each bulk bag discharger frame includes a cantile-
vered I-beam with an electric hoist and trolley, allowing a single worker to raise and position a bulk bag above the unit’s receiving hopper. Because the discharger is automatic and dust-free, as many bulk bags as are needed can be discharged rapidly and safely. A cross- shaped bag-lifting frame attaches to the straps on each corner of the bag, and the electric hoist lifts the bag into place on the discharger frame. The operator pulls the bag’s outlet spout through a flow-control valve whose elliptically-contoured bars
74 COMPOUNDING WORLD | February 2016
www.compoundingworld.com
conveyor, 10.5m (34.4ft) long and 114mm (4.5in) in diameter, transports talc at a 45˚ incline to an inlet hopper for blending with other additives and resins prior to compounding. The conveyor’s flexible stainless steel screw has a specialised geometry to handle non-free- flowing materials. Flexicon says that one benefit of this particular screw design is its ability to convey talc consistently regardless of its moisture content. “The density of talc often decreases when it is conveyed because ambient air reduces its moisture content,” says Drabbe. “A lower density means more talc volume, reducing the amount that gets added to a formulation and affecting production throughput in a negative way.” US company National Bulk Equipment (NBE) has
developed a bulk bag unloader to address specific dust reduction and process operation efficiency require- ments. The unloader is claimed to provide closed-loop dust containment, to protect personnel from migrant dust, to improve bag spouting efficiency, and to protect process operations from contaminants. NBE says previously the operation often caused
material dust release during the bag spouting sequence, which presented operator hazards and slowed process cycle times and changeovers. Its bulk bag discharger enables the operator to spout the bulk bag easily and
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