At this spring’s Plastics Recycling Conference in New Orleans, Sandy Guthrie, president of ADG Solutions, Fairfield, Conn., discussed recent progress in addressing difficult recycling applications. First, his firm is representing Fimic of Italy, which has new features in its self-cleaning automatic filter changer (see Keeping Up with Technology, Jan. 2012). For heavily contaminated (3% to 10%) agricultural film, the latest generation can now filter down to 200 microns without backflushing, vs. 300-400 microns previously. Instead, a mechanical scraper wipes off the screen, which has a very large filter area (12.5 to 28 in. diam.).
According to Guthrie, backflushing cannot handle such heavy contamination, and the mechanical scraper also wastes less resin. For very fine filtration (to 40 microns) of less heavily contaminated film, the Fimic filter also has a backflushing mode of operation.
Guthrie said one interesting recent application for the Fimic filter is recycling construction and agricultural film reinforced with PET cord between two layers of PE film. Installed in January at Raven Industries, Sioux Falls, S.D., the system uses a 6-in. ram-feed extruder from Davis-Standard, Pawcatuck, Conn. After shredding the film, it is fed into the extruder at a temperature that melts the PE but not the PET. The latter is strained out by the Fimic filter. A melt pump delivers the melt to a “shower die” and to a vertical devolatilization chamber. After secondary filtration, the melt passes to an underwater pelletizer and dryer from Gala Industries, Eagle Rock, Va. The last steps are a fluid-bed dryer and pellet classifier, followed by a Gaylord box filler and weigh scale. The system is running at 2000 lb/hr and could go to 3000 lb/hr, Guthrie claims.
He also noted that this summer, his firm will install complete washing lines for heavily contaminated (50-70%) agricultural film, using equipment from Tecnofer of Italy, which ADG also represents. Using centrifugal technology, the system can produce 2000 lb/hr of cleaned material for reprocessing into film.