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Recycling & waste management.

Recycling & Waste Management

This year's NPE offered shoppers a rare chance to look over an a-la-carte menu of recycling machinery, with tantalizing offerings like a color-separation method for flakes and pellets or a small, inexpensive new densifier for film and foam waste. NPE also served to take some of the mystique out of big turnkey recycling lines and "custom" commercial plants, as more machine makers proudly identified where their units are used.


Plastic Resin Separation Specialists Inc., a technology development company in Anderson, S.C., displayed packets of flakes and pellets representing before and after visual sortation by its proprietary technology. Other recyclers are known to be working on color sorting flake, but Plastic Separation has the first commercial system. It will sell machinery under license with a production-based royalty.

The system involves "a series of eliminations made by a viewing process," explains executive v.p. and co-owner Rob Roy. "You start with separating light from dark. Then it's not important what colors you take out next." Color separation is one of nine separation technologies utilized by Plastic Separation and the only visual one. Roy says isolating one color involves "squirrel caging" (as in chasing your tail) to shunt some of the predominant light or dark color off to the side to raise the concentration of the color you're extracting, like blues from a predominantly white material stream. The system sorts best when colors or materials are evenly mixed. If colors are concentrated in layers, they should be mixed before sorting because looking at a lot of one color slows sorting, he says.

Roy says Phillips 66 Co., Bartlesville, Okla., is "very interested" in the technology. Phillips is in a recycling joint venture with Partek Corp., Vancouver, Wash., which uses a separate color sorting technology developed by Partek that is limited to scanning a proprietary size granulation (see PT, Nov. '90, p. 103). Partek CEO Victor Bitar says Partek uses "two competing machine vision technologies to separate natural HDPE from everything else." The problem has been getting commercial rates of granulation, he says. Phillips/Partek's separation technology will also be for license once commercial.


Plastics Densification Ltd. from the U.K., whose U.S. subsidiary is Plastics Densification Inc., c/o Archer Marketing Corp., New Rochelle, N.Y., showed its new Styromelt PD2000 densifier machine at NPE. PD2000, at 6 x 3 x 1.6 ft, is not much bigger than a home refrigerator and processes packaging foam waste at up to 100 lb/hr. A smaller "commercial" model targets fast-food plastic waste and processes up to 5000 styrofoam cups/hr.

Both densify using heat, not blades or grinding, in a cast aluminum chamber ringed with internal heating elements. The elements are similar to heater bands for extruders developed by Plastics Densification's sister company Exotherm in the U.K. and covered by "world patent applications," the company says. Close temperature control of the melt (at 428 F) "prevents burning, but removes gases which can represent more than 95% of the volume of many PS foam products," the company says. Melted waste is cast into bricks, water cooled, and ejected for recycling or use as efficient fuel, the company says. Three to four garbage bags of PS waste or 1000 foam cups make a 2-lb brick in about 3 min, says Plastics Densification marketing director Paul Edwards. A heated slicer for large block foam can be added to the industrial model for faster feeding. A flue with extractor fan and carbon filter is said to control odors, and the densifier can safely be left on, even when empty, the company says. The industrial PD2000 costs $35,000; the commercial restaurant model $15,000.

The company says its booth at NPE attracted interest from company's with particular waste problems, like a rug company with a lot of nylon fiber scrap. So Plastics Densification is looking at a high-heat unit for nylon 6/6. It's also developing a small densifier for vending machines and a hospital unit to cast waste plastics together with "sharps" (syringes and scalpels) into one sterilized block.


Gala Industries Inc. in Eagle Rock, Va., a maker of recycle dryers, exhibited its recycle rinsing unit for the first time. "We've sold three complete systems [including dryers] and 10 individual washing units," says Gala salesman John Clark. The rinse unit, on the market about six months, is used to remove fines, dirt, loose paper, and other residues from PET and HDPE flake as part of a new cryogenic cleaning system from Western Environmental Plastics Inc. in Lewisville, Texas (see PT, June '91, p. 37).

Gala's high-pressure spray system rinses dirty flake first using slurry water from the wash stage. Flake then enters a vertical wash column from the bottom and is carried upward by turbine-like rotor blades, as water jets spray clean water out from the center. The rotor blade is enclosed in a stationary screen, through which the rinse water passes. Wash rates vary from 10 lb to 5000 lb/hr, depending on unit, material and contamination. Water filtration can be added. A 1000 lb/hr wash unit costs $30,000 with filtration, $14,500 without.


Hartig Plastics Machinery div. of Somerset Technologies Inc., New Brunswick, N.J., displayed its new 35/60 dual-diam., double-vented Reclaim Extruder for the first time. The 35/60, with 500-600 lb/hr throughput, is designed for continuous feed of materials like OPS and OPP web scrap (up to 12 lb/cu ft) and LLDPE and HDPE film. It also processes ground PP foam without predensifying, Hartig says. A two-piece screw construction allows easier screw separation and removal than one-piece types, according to the company. The 35/60 costs $200,000 including Beringer screenchanger and underwater pelletizer.

Crown Machine div. of Crown Products Inc., West Chicago, Ill., says it shipped direct from NPE its new Water-Ring Repelletizing System for HDPE to the Chicago plant of the Plastic Recycling Alliance (Du Pont Co./Waste Management Inc.'s joint recycling venture with plants in Philadelphia and Chicago). Crown's system comes in two sizes. A 2000 lb/hr model has a 6-in. extruder with grooved feed section for flake (a 5-yr-old design with a hydraulic manual slide-plate and 8-in. screenchanger for greater screen life) and Crown's new water-ring pelletizer (Crown previously made only underwater dry-face and spray-face pelletizers). The 2000-lb system costs approximately $350,000. A smaller 600 lb/hr model, which hasn't been built yet, is aimed at small amounts of industrial film reclaim. It has a 3.5-in. extruder and costs $175,000. Crown can also supply a 5000 lb/hr system using an 8-in. extruder.

The PRA is also said to be adding a new patented backflushing screen-changer from Joachim Kreyenborg & Co. GmbH in Munster-Kinderhaus, Germany. Kreyenborg's K-SWE backflush screenchanger, at NPE for the first time, has only been on the market 10 months, but already 23 have been sold in the U.S., says U.S. agent Precision Equipment Inc., Marietta, Ga. All but two are in recycling applications, says Precision president William Kilfara. The K-SWE backflush screenchanger, available in models with throughput rates up to 30,000 lb/hr, has two separate spiral flow channels and two separate screens for plastic. This allows continuous operation while the screen in one of the cylindrical screen bolts is flushed. The patented design voids the passage behind the screen, so no melt collects that can decompose and cause gels, Kreyenborg says. Filters can be reused up to 30 times; a pressure-based alarm indicates when screens need changing. The 2000 lb/hr K-SWE model with Allen-Bradley controls costs approximately $70,000 with backflush ($50,000 without).

HPM Corp., Mount Gilead, Ohio, reports promising early results with its Double Wave screw in reclaiming HDPE milk bottles for the Phillips/Partek venture, which is expected to start construction soon on its first plant in Tulsa, Okla. Phillips/Partek will use 4.5- and 6-in. versions of this screw, HPM says. The Double Wave screw reportedly provides low heat history and good mixing at double the output rate of a screw Partek tried previously. The Double Wave is "very forgiving" with commingled plastics, says HPM v.p. Ronald Akialis, who adds that HPM has "five to six projects going on in reclaim."


Continental Polymer Corp. in Worcester, Mass., is marketing a Hong Kong-built double-vented, two-stage recycling line that it has used in-house for nine years. "Constant improvements" have been made to it along the way, says president and owner Alan S.C. Chan. The WH-140DI, displayed for the first time at NPE, includes granulator, two-stage extruder, and pelletizer for under $100,000. Three lines at Continental process 45,000 lb/day, six days/wk in Wooster, or about 12-15 million lb/yr, mostly for export, Chan says. Three more Continental machines process post-consumer recycle in Canada and two in Rhode Island, he adds.

"This is one of few cost-effective machines that somebody without state grants can look at," says recycler Doug Casella, owner of Casella Waste Management in Rutland, Vt., who's buying one. Casella sells baled PET and HDPE bottles, but says the market is so full of new plastic collection programs that waste haulers can't sell bales profitably. So he's moving upstream to make higher-value pellet.

Continental's two-stage extruder has two oversized screen packs (10-in. diam. screens on 5.5-in. diam. screws). It also has a strand pelletizer with "air-stripper" blowing air over the strands to remove water and a movable cyclone for more efficient loading of gaylords. Washing equipment isn't included, but Chan says, "Washing needs simple flotation tanks for separation and a dryer. I can tell anyone how to set that up easily, and it will save money."

PHOTO : Continental Polymer's economical Hong Kong-built recycling line made its first appearance at NPE. With pelletizer and cyclone (left) and double-vented, two-stage extruder, it's under $100,000.

PHOTO : Plastics Densification's machine turns three to four garbage bags of food-contaminated PS waste or about 1000 foam cups into a sterile 2-lb brick in about 3 min.
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Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:National Plastic Exposition wrap-up: shopping guide to the latest technology
Author:Schut, Jon H.
Publication:Plastics Technology
Article Type:Cover Story
Date:Aug 1, 1991
Previous Article:Materials handling.
Next Article:Heating & cooling.

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