Growing activity in carpet recycling has prompted new modifications in counter-rotating, twin-rotor continuous mixers. Technical Process & Engineering Inc. (TPEI), Lehighton, Pa., which has built continuous mixers for 30 years, recently introduced a patented rotor design for hard-to-recycle, low-bulk-density materials like carpet fiber and film (U.S. Pat. 7350960, Apr. 2008). Two of its model 9FRE mixers have been sold to compound and pelletize recycled PP carpet fiber at 4000 to 8000 lb/hr. The beefed-up mixing rotors have a first section with Lowenherz, or V-shaped, threads scored in the outer periphery of the rotor to increase feed rate, followed by standard melting screw flights, which feed into a “wing-type” helical mixer in the second half of the rotor. A patented pneumatic seal (U.S. Pat. 6390666) with a stepped metallic sleeve improves the rotor’s upstream seal by purging contaminants before they reach the seals. The mixer’s body section slides in and out on tiebars, exposing the rotors, which can be changed in 20 min. TPEI’s continuous mixers are supplied as a unitized system with the mixer feeding a continuous ribbon directly into the throat of a single-screw discharge extruder for pelletizing or direct extrusion. The transition between mixer and discharge extruder includes a proprietary “J-Block” feed section for even flow of material into the extruder without surging, eliminating the need for metering or melt pumps. (570) 386-4777 • www.tpei.com
Technical Process &
892 Blakeslee Blvd. Dr. West Lehighton, PA 18235
Phone (570) 386-4777 Fax (570) 386-4120
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