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Recycling update: new resins, new ventures & new technology.

Recycling Update: New Resins, New Ventures & New Technology

Automatic color-sorting technology looks to be the next major step forward in plastics recycling. Demand for color separation is increasing as bottle makers discover that black isn't necessarily beautiful inside a bottle. Up to now, bottle makers using HDPE recycle had a choice of clear milk-bottle homopolymer, which suffers from poor stress-crack resistance (and is hard to come by), or mud-colored or black copolymer made up of mixed colors. But now, two recyclers say they can mechanically separate mixed bottles by color as well as material. Both companies have major technical backing and both say they've succeeded in pilot-plant testing and are planning production facilities for 1991. At least one of them will offer the technology for license.

There's other new recycling technology available for license, as well as new virgin HDPE resins that can aid in HDPE recycle, and a new crop of recycling ventures and agreements to report.

NEW HDPEs AID RECYCLING

The big new contribution from resin companies to recycling is the marketing of new HDPE grades with substantially higher environmental stress-crack resistance (ESCR) than standard. Wider use of these resins could double the amount of post-consumer recycle (PCR) material that can be safely put into a monolayer motor-oil bottle, for example. Houston-based Exxon Chemical Co., Occidental Chemical Corp, and Soltex Polymer Corp., all make high-ESCR HDPE resins by a variety of processes, which they say yield resins that test at up to 50 times the ESCR of "workhorse" blow molding HDPE for household and industrial chemical (HIC) uses (see PT, Sept. 90, p. 13).

Exxon's Superflo quart oil bottle is now a 2-million-lb/yr market for recycle at 15%, and recycle content is slated to rise after it is switched early next year from using Soltex's newest high-ESCR resin (Fortiflex HP55-50-153) to Exxon's brand-new HD 9856 B, said to have even higher ESCR, which is made in a new Mitsui-process reactor that started up in October (see story, p. 25). The bottles are molded by Sewell Plastics Inc., Atlanta.

Soltex is still the only resin company selling a blend of high-ESCR HDPE with PCR (from Eaglebrook Plastics Inc., Chicago, and three-year-old Partek Corp. of Vancouver, Wash.). Soltex is sampling the blend, priced about 5% over virgin.

"We've done tests with the new Oxy and Exxon resins, and there's no question. They're superior in terms of stress-crack resistance," says Gerry Claes, director of environmental programs at Sonoco Graham Co. in York, Pa., which puts 15%-20% PCR in monolayer oil bottles and 25% PCR in some three-layer detergent bottles. "With these new resins we can go easily to 30% PCR, and with more testing maybe to 50% in the monolayer bottles, which is where the big benefit comes."

NEW SYSTEMS FOR LICENSE

Graham (soon to become Graham Packaging when Graham Cos. buys out Sonoco Products' 40% ownership) has more than a passing interest in recycling. In late September, timed for the date Pennsylvania's curbside collection law took effect, Graham opened the first 10-million-lb/yr line of a planned 20-million-lb, $5-million captive recycling plant, becoming the first bottle company to make its own recycle. Without its own recycling plant, Graham was "stretching available supplies" of recycle, says sr. v.p. Phillip Yates. Graham puts 15-20% PCR into black oil bottles, using commingled HDPE, but only 15% dairy-grade homopolymer PCR in non-black oil bottles, because of extreme short supply of dairy PCR.

Graham Engineering will also offer for sale recycling systems like the one it designed and built for its own plant. The systems use modified stock parts for bale breaking, shredding, silo blending, washing, and drying, plus a vented-barrel Graham extruder with hydraulic two-stage screen changer. It will cost $1.5-2 million complete, depending on configuration.

A notable feature is that after bale breaking, metal detecting and shredding, the line splits into two small, side-by-side lines to permit faster cleaning of PCR. Cleaning begins in two double blenders (each with four blade shafts) driven from below at 1500-1700 rpm by two 125-hp motors. In the blenders, angled 6-in. blades chop bottle strips into flake inside a 5-ft-diam., sieve-like drum. Friction removes paper from plastic, small flakes exit through the sieve holes; and rinse water running through the cleaner is discharged. From the cleaner, flake passes up twin ramped augers under pressured-water nozzles into twin 800-gal rectangular, open tanks full of clean water. In the tanks, slowly turning drums (two with paddles, a third with combs) move flake along to a second pair of ramped augers with a pressured fresh-water rinse. Then flake goes to two high-speed centrifugal dryers to remove water before extrusion into pellets. (CIRCLE 10)

In trials at the new plant, Graham ran a trial sample of 500-600 lb and changed triple screen packs every half hour. Workers say pressure built up in the extruder and blew screens out several times, so they raised the alarm setting from 5000 psi to 6000 psi backpressure before screen changes. Plant manager Stephen Jackson says that with the adjustments, they can run the line much faster than the 2000 lb/hr it was designed for. But even at 2000 lb/hr, the line outruns hand sorters using a system of chutes. So Graham will have to manually presort and rebale, separating plastic by type and color.

Oil bottles, which aren't used currently, are separately baled to be run through a special oil-recovery system (which will be installed early next year) before reprocessing. Graham will build the second processing line in early 1991, once needed modifications are identified from running the first, Claes says.

Meanwhile, N.Y.C.-based Lever Brothers announced it has committed to use 10 million lb/yr of recycle in packaging from Graham, or the equivalent of the entire output of the first line. That translates into 25-30% PCR in all Lever bottles made by Graham, says Lever president/CEO David Webb. Graham began putting recycled milk-bottle resin into Lever's red Whisk bottles and blue All detergent bottles at two plants in June. Lever, whose bottles also come from Owens-Brockway and Continental Plastics, says it will have 25-35% recycle in all bottles within a year. That's a demand for about 40 million lb/yr of PCR, says Melinda Sweet, director of environmental affairs.

Graham may have trouble coming up with 10-20 million lb/yr of supply for its new venture, established recycle buyers say. Graham bought an initial 5 million lb of mixed bottles from Domtar Inc. in Canada of the 10 million pounds Domtar was left with after the failed project with Dow. Graham also tested bales from N.Y.C., which began limited curbside plastic collection in October. New York's East Harlem Recycling facility was already getting 2 million lb/yr of plastic it didn't ask for, thrown into its blue recycle bins for glass and metal, so the city program has big potential.

(Availability of recycled HDPE will get a big boost when Eaglebrook completes a doubling of its Chicago capacity by the end of the first quarter 1991. Exact capacity figures are confidential. Construction on the new processing line will start before the end of the year at the present facility, says sales manager Kyle Wright. An automated system to sort dairy containers from mixed bottles is also planned to be on-line by the second quarter of 1991. Eaglebrook now sorts manually. Color sorting isn't planned at present, Wright says.)

Incidentally, Graham was surprised to find that customers care about the color inside a bottle. There was a negative reaction to a test of a 15%-PCR, two-layer oil bottle that was yellow outside and black PCR inside, Claes says. So Graham will bale separately yellow/yellow green, red, blue, white, natural (milk and water bottles), and clear PET or PVC. Color sorting of PCR will allow pairing the color of recycle with a similar color of virgin material in a multilayer bottle.

There's a related problem with three-layer detergent-type bottles. Up to now, processors have used expensive and scarce natural-color dairy recycle in the middle layer, because black or mud-colored PCR layer made from mixed colors might show through the colored virgin layers. Color sorting to match virgin with recycle colors is very much of interest here, too.

LOOK, NO HANDS!

But the big news in color separation is that two other recyclers, Wellman Inc., in Shrewsbury, N.J., and Partek, each say they're sorting colors mechanically on a pilot scale (by very different methods) and plan production next year. "It works," says Wellman recycle manager Caroline Mixon of the firm's pilot line. Most sorting of colors and resins takes place immediately after bales are broken. Mixon says it took not one technology, but "all the known theories combined to build the system, including automatically decapping bottles. Our goal is not just to separate by resin type, but also by color, to yield as little black as possible."

Wellman tested its color-sorting technology in segments in its Allentown, Pa., plant, then assembled a full pilot line in Johnsonville, S.C.A production-scale project could be announced in December. Wellman will probably still buy PET and HDPE milk jugs separately, but could then accept commingled bottles as well. Initially, Wellman will sell recycled resins--in colors--but ultimately will develop end-use products like containers and trash bins. (Wellman now sells its milk-bottle HDPE almost exclusively to Owens-Brockway.)

Wellman's Allentown plant sent a load of "tailings," highly contaminated bottles like oil bottles, to Western Environmental Plastics Inc., in Lewisville, Texas, for a demonstration of Western's process of compatibilizing mixed plastics (on which a patent has been applied for), as well as its cleaning process. Western's president Kurt Ruppman says the load was converted to a "usable polymer, combined chemically--not in layers or just a blend." The mix was injection molded into black, 100%-PCR flower pots, of which Western shipped some 50,000 in October to growers.

The second hands-off color-sorting technology is Partek's, to be commercialized in an HDPE-recycling joint venture with Phillips 66 Co., Bartlesville, Okla. Partek and Phillips plan to build the first full-scale plant using Partek's proprietary cleaning and sorting technology, which is said to be applicable to other plastics besides HDPE. The $3.5-million, 20-million-lb/yr plant (intended to be the first of several for the venture) should be operating by mid-1991 in the Midwest or the West Coast. Phillips will sell all the output from the plant--which could make it the first basic PE producer to sell a 100%-PCR material. The joint venture will plan additional recycling plants once the first is operational.

Phillips and Partek also formed a second, unannounced joint venture to license Partek's cleaning and sorting technology worldwide, says Partek CEO Victor Bitar. Partek's pilot R&D line in Vancouver, which produced 3 million lb in the first three quarters of this year, stirred interest from several other resin companies, six of which signed confidentially agreements to see it and sample resin.

The heart of Partek's system is a patent-applied-for granulation technology, which makes "chip," rather than flake, all of a uniform 3/8-in. size. This uniformity is critical to the color separation, because the absence of very fine particles allows 99% accurate sorting. "After you get all the same size, a machine can scan and reject," says David Smith, director of business evaluation at Phillips. Partek has a license from the joint venture to develop the granulation system and will have a test granulator on a curbside collection truck soon.

Partek's color-sorting system can successfully cull dark from light, and clear homopolymer from everything else. For now, it can't distinguish between colors like blue and red, but that's only a matter of time, maybe using infrared or ultraviolet detection, says Smith. Incidentally, light-dark separation per se isn't brand-new. UK-built Sortex machines, originally developed to sort rat droppings from grain, are already used by chemical companies to get dark pellets out of light pellets, for instance.

Partek's color-sorting stage, just now being installed on the pilot line in Vancouver, will take place after grinding and washing, so it can be integrated into the production line later, if it isn't perfected when the plant is built. Paper is removed kinetically without chemicals after drying. (CIRCLE 11)

Du Pont Co., Wilmington, Del., also recently set up a joint venture with Chicago-based American National Can Co. (ANC) to recycle syrup bottles and multilayer ketchup bottles. Separation will take place at the Chicago plant of Plastic Recycling Alliance (PRA), a joint venture of Du Pont and Waste Management, Inc. of Oak Brook, Ill. One goal of the Du Pont/ANC venture is to develop automatic sorting technology to identify and separate ANC's multilayer bottles from other plastics.

PHOTO : New technology to eliminate hand sorting of different colors is the coming thing in bottle recycling.

PHOTO : Four specially designed Werner & Pfleiderer two-stage, twin-screw compounders are destined for new plants of the National Polystyrene Recycling Co. A first, 13-million-lb/yr plant opened in Corona, Calif., and others are to open in San Francisco, Philadelphia and Chicago by year's end.
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Author:Schut, Jan H.
Publication:Plastics Technology
Date:Nov 1, 1990
Words:2176
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