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Sorting Film Plastics in MRFs Current Status. Current single-stream sorting technology depends heavily on rotating shaft screens. Film plastics wrap on the screen shafts and disks. Degrades screening & sorting efficiencies Increases time spent cleaning screens
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Sorting Film Plastics in MRFsCurrent Status • Current single-stream sorting technology depends heavily on rotating shaft screens. • Film plastics wrap on the screen shafts and disks. • Degrades screening & sorting efficiencies • Increases time spent cleaning screens • Increases possible heat/fire hazards due to friction • Two-stream processes fare no better: • Container sort lines have trommels and air classifiers • Film contamination blinds screens at paper mills • MRFs now sort film mainlyto protect the system vs. recovery
Sorting Film Plastics in MRFsMethods • Options to sort film plastics & associated issues: • By hand • Relatively ineffective on singular items • Difficult to assure quality • Rotating shafts in advance of screens • Only in prototype use? • No control for quality – really a pre-screen role • Reverse air sorting • Same comments as prior item • “Optical/Sensing” equipment • Best opportunity for quality control • Must be installed after screens
Sorting Film Plastics in MRFsBeyond the Mechanics… • Specifications and Quality • Different grades for ‘shrink wrap’ and ‘retail bags’ >>> MRFs make a mixed grade • Contaminants: food products, paper, wood, food wraps, oil and grease, metals • Given that most sorting will occur at the front of the sorting process where materials loading is heaviest, these contributors are difficult to minimize. • Added issue: Import restrictions relative toquality for offshore markets.
Sorting Film Plastics in MRFsMaking it Easier • Selective targeting and clear information • Residential: just retail bags? • Commercial: just shrink wrap? • Prepare materials for sorting • Place bags within bags [“bag in bag”] • Accommodate increased sorting and handling costs • Few MRFs are designed (bunkers, baling, storage) to add this material to their recovered products list. • Should not depend on material value tofully defray operating costs.