Each year, about five (5) million ton of shredder residues are landfilled in the US. Similar quantities are landfilled in Europe and the Pacific Rim. Landfilling of these residues results in a cost to the existing recycling industry and also represents a loss of material resources that are otherwise recyclable. In this paper, the authors outline the resources recoverable from typical shredder residues and describe technology that they have developed to recover these resources

Daniels, E. J.

Jody, B. J.

Pomykala, J., Jr.

UNT Digital Library

MATERIALS RECOVERY FROM SHREDDER RESIDUESE,J. Daniels, B.J. Jody, and J. Pomykala, .Tr.Argonne National Laboratory9700s. Cass Avenue~E~~\~~~ Argonne, IL.60561pJJ6 011 WABSTRACT(’-JS- l-lEach year, about five (5) million ton of shredder residues are Iandfilled in the UnitedStates. Wnilar quantities are landfilled in Europe and the Pacific Rim. LandfiHing of theseresidues Rsults in a cost to the existing recycling industry and also represents a loss of materialresou~es that are otherwise recyclable. In this paper, we outline the resources recoverablefrom typical shredder residues and describe technology that we have developed to recover theseresources.LiiEElThe 8Ubmitted manuxript hat tin autho,@.j~d:, cfmtractOr of the U. S. Gwarnme”f.Accodi@Y, the il. S, Government tiin. ●nOtWXChlSiw+.rOydly-frW Iicenm tO p@ji’hor reprcduca the nublished form of tKIZcontribution, or allow others to * go, for— — — .DISCLAIMERThis report was,.prepared as an account of work sponsoredby an agency of the United States Government. Neitherthe United States Government nor any agency thereof, norany of their employees, make any warranty, express orimplied, or assumes any legal liability or responsibility forthe accuracy, completeness, or usefulness of anyinformation, apparatus, product, or process disclosed, orrepresents that its use would not infringe privately ownedrights. Reference herein to any specific commercialproduct, process, or service by trade name, trademark,manufacturer, or otherwise does not necessarily constituteor imply its endorsement, recommendation, or favoring bythe United States Government or any agency thereof. Theviews and opinions of authors expressed herein do notnecessarily state or reflect those of the United StatesGovernment or any agency thereof.DISCLAIMERPortions of this document may be illegiblein electronic image products. Images areproduced from the best available originaldocument...●✎INTRODUCTIONThe most cost-effective process for recovering rnaterz’ds from obsolete consumerdurables such as cars and appliances is to shred them and then recover the materials of valuefrom the shred. This is clearly evident by the fact that this is the common business approach toprocessing obsolete durables today. Each year, more than 30 million obsolete cars are removedfrom service, and after useable or rebuildable parts are recovered by dismantling, most of thesecars become feedstock for shredding operations. Obsolete cars represent the single largestsource of scrap steel for steelmaking. Whereas ferrous and non-ferrous metals can be cost-effectively recovered, the other materials from obsolete cars and appliances have not beenprofitably recovered to date. Consequently, about 15 million tons of waste, commonly referredto as auto shredder residue are kmdfilled each year throughout the world, about 5 million tonsper year in North America, 5 million tons per year in Europe and 5 million tons per year in thePacific Rim. Clearly, landfilling of this resource imposes a direct cost on existing shreddingoperations. Less obvious, however, is the opportunity cost that resuks from dumping theprofitable materials resources that are contained within shredder residues.In this paper, we outline an approach to maximize the profitable recovery of materialresources from shredder residues based on extraction technology developed at ArgonneNational Laboratory.SHREDDER RESIDUE:OPPORTUNITY COSTS AND PRODUCT OPPORTUNITIESThere are about 200 shredder operators in North America and more than 500 throughoutthe world. Each shredder processes a different mix of feed material of cars, appliances, andother prompt and obsolete metal scrap. Each shredder operates their process under slightlydifferent conditions. For example, most use two stages of magnetic separation while others useonly one. Some use eddy current separation for non-ferrous metals recovery, others useflotation systems and others do not recover non-ferrous materials on-site. Some shredders areoperated dry while others spray the infeed material for dust control. Obviously, thecomposition of shredder residue varies from shredder to shredder and from day to day at eachshredder depending on the mix of feed material.Typically, we have found that shredder residue (dry basis) contains about 10% ferrousand non-ferrous metals, 10% polyurethane foam, 40% fines material (less than 1Ainch) thatcontains metal oxides, glass, dirt, sand and wood, and 40% other organics inchding fibers andmixed polymers. Although this composition may vary slightly (more so with regard to metalscontent), variations that we have observed do not significantly alter either the overall approachor ultimately the basic process design for recovering materials from shredder residue.Over the years, any number of alternatives to landfilling have been proposed for dealingwith shredder residue ranging from use of shredder residues as an energy source (e.g.incineration), use of shredder residues as feedstocks for production of fuels or chemicals (e.g.pyrolysis, gasification), and use of shredder residues as fillers in other bulk materials (e.g.plastic logs) (1,2). While any of these options might be technically feasible, they ignore theinherent value of the materials contained within shredder residue and can, at best provide littlemore than an offset against the direct costs of landfilIing shredder residues. For example, evenin the case of converting shredder residues to fuels or chemicals, the maximum value of the.,. .shredder residues cannot exceed that of an alternative feedstock such as coal. In this case, thevalue of the shredder resides would be about $0.01 per pound. Similarly, if shredder residuesare used as fillers, there are many low-cost fillers that the residues must compete with.On the other hand, if we consider the values of the individual materials contained withinshredder residue, in particular the polymeric materials, some of which have values in excess of$0.25 pa pound, we can then see the potential in recovering the opportunity costs of thesematerials— if we can recover them in a quality sufficient to gain this market opportunity.SEPARATION/EXTRACTION TECHNOLOGY: PRODUCT RECOVERYTypically, we can expect about 75,000,000 pounds of shredder residue to be generatedas a result of processing about 100,000 auto hulks for metals recovery. The technical approachthat we have taken to process shredder residues for materials recovery includes a first-stagebulk separation followed by second-stage processes for recovery and conditioning of productmaterials. The overall process-materials flow is outlined in Figure 1. Products which aretargeted for recovery include: a clean polyurethane foam, conditioned iron-oxides, and selectedhigh-volume polymers including polypropylene, polyethylene, EPDM, ABS, HIPS, nylons,PVC, and polyester Tl?. Ferrous and non-ferrous metals are recovered as by-products duringthe recovery of the targeted materials. The principal residual material remaining is a plasticsconcentrate that will include more than 20 different types of lower-volume automotivematerials. At present, because of volume and value, these materials cannot be cost-effectivelyrecovered as individual materials.Bulk SeparationThe first-stage bulk separation is accomplished using a specially designed two-stagetrommel that yields three product fractions: fines, dirty polyurethane foam, and a plasticsconcentrate. The oxides fraction includes materials of less than ?4 inch, the foam fractioncontains large, light materials and is predominantly large chunks of flexible-urethane,automotive-seat foam and the plastics concentrate will contain the balance of the incomingshredder residue. Each of the three fractions is then conveyed to second-stage processing formaterials recovery and conditioning. Magnetic head pulleys on conveyors facilitate therecovery of ferrous metals entrained in the fractions.Second-Stage ProcessingSecond-stage processing is required to recover products that meet the needs of themarket. Recovered products include clean polyurethane foam, an iron-oxides concentrate, andselected polymeric materials.Typically, the polyurethane foam materials recovered from shredder residue will becontained entrained oils, dirt and some metals. The foam pieces will also be of varyingdimensions ranging from about l-inch pieces up to 8-inch chunks. To produce a marketablefoam product, the foam is first sized in a secondary shredder to produce consistently sizedpieces about 1 inch x 1 inch x 4 inches. Shredding also facilitates the liberation of entrainedmetals and dirt.rinse and dryerAfter shredding and screening, the foam is conveyed to a continuous-wash,system, Figure 2, to produce clean foam for the rebond market. Heavy+%components such as rubber compounds and non-ferrous met.ds are recovered from the foamwash tank. The cleaned and dried foam is then baled for shipment, Figure 3. In general, onepound of clean foam is recovered from two pounds of dirty foam (3,4).Oxides ProcessingThe fines fraction from shredder residue is typically about 40 weight percent of theshredder residue, It will contain metal-oxides, dirt, glass, sand and residual amounts oforganics including oils and small-particle-size polymeric material. Magnetic separation of thismaterial followed by wet sink-float separation can produce a high-quality iron-oxideconcentrate (greater than 60% iron, with low concentrations of alkali metals and residualorganics) that can be used as an alternate iron unit for cement making. The iron-oxideconcentrate is typically about 1/3 of the weight of the fines fraction from shredder residue.Polvmeric Materials RecovervThe mixed-polymer concentrate from the bulk separation of shredder residue is furtherprocessed to recover selected polymers. The concentrate will include materials of varyingparticle sizes. Therefore, the first step in recovery of specific polymers from this mix isgranulation, to produce a consistent particle size of about % inch for subsequent separation.Separation and recovery of specific po&mers is accomplished using a wet sink-float systemthat includes froth-flotation for separation of equivalent-density polymers from each other.A two-stage sink-float system is used to produce three initial cuts: a light, a heavy and amiddling fraction. The light fraction will contain light rubber compounds such as EPDM andpolyolefins. The EPDM can be recovered from the polyolefins using sink-float and thepolyolefins can be separated from each other using froth-flotation. The middling fraction willcontain polymers such as ABS, ABS-PC alloys, SAN, PC and HIPS. The HIPS can then beseparated from this fraction using froth-flotation (5). The ABS, SAN, and PC materials arecompatible and can be recycled without further processing. The heavy fraction will typicatlycontain a PVC concentrate. Other high-volumelhigh-value materials such as nylons andpolyester TP can be recovered using staged sink-float and froth-flotation. Recovery of thesematerials accounts for about 2/3 of the mixed-polymer fraction produced by the bulk separationstage, leaving a mixed-plastics fraction containing about twenty different polymers. Thisresidual fraction is predominantly thermoses that might have value as a fuel feedstock becausethe therrnosets cannot be re-used directly.MARKET UXWESVarious aspects of the process that we have developed have been confirmed throughlarge-scale-pilot demonstrations. These include recovery of a clean polyurethane foam,recovery of an iron-oxide concentrate, and recovery of a high-quality ABS product. Producttesting has confiied that these materials meet the requirements of the market, Figure 4. Thekey to long-term viability in recovering materials from shredder residue, is the ability torecover materials of consistent quality day in and day out.4.-=CONCLUSIONSA process for recovering materials from shredder residue has been developed. Keyaspects of the process such as recovery of the polyurethane foam, recovery of iron-oxides, andrecovery of a high-quality ABS have been demonstrated at the large-pilot scale. The balance ofthe process (Le. polymer recovery) has been confirmed by bench-scale experiments. Althoughactual yields will vary depending on the materials fed into the shredding operation, recovery ofthese materials from shredder residue can result in revenues in excess of $150 per ton ofshredder residue.Shred&w Residue75,000,000 poundsE’..”,.. ””....., ,... FefrOus Metsfa- 3,375.000...””.-.””...”. Non#.emW Msials- 3,37S,oaoLWfyPuF CWn FoamS,ooo,csxf - 2.5c0,mRe@ctfXeandDiri- 2r500QOLf=’”~;~=L:MixedRNelee:l} AsunifainooundsL~m’”’dti,,lsmao,ooo (Sxdlrdhg HIPS from eppfiano13s)_EPDM, PoJ@efina ksmmsrs-E,,-ASS, ASS-PC SAN,PC, HfPS”~gr”F.Jylom-3.243,899WC- 2,615,S@2Po@sler TP- 9s4,924MIxED F1/1.WCS am3s5Aotsl 274,916 tome.4&Isa 4t8532.718 PokaaterTS 2.732,623Afis , 11:015 F&amar suti 1,27iAn@ 815 Wmerroida 2,111PC- EW36 Pnryp?lymelwt+asrllfids is,wPPO .$tyane 86s,SsS Po4yewOne 11,14AsA afl .841 Pt4@ralfr?n”ds 7s2SLltyra 1325UJ PoIyures RIM 446,59EPoxy 93,X9 43$,2XPllermlic !s302ss ~w.k Elsafonw wPOW* @#4 Urakrrss fiiiid 1,72s212PaIyemr Haakmrr xi4S22 Vinqf Ester 454,4U2j 7S rrdkm &IIn* of sMadCar reeWe is produced by shredding tit 100,600 auto fwlks.3) Pdyrrer cmpceitb is baaedon tQS2 eslamotka use,excfudngttres4) HIPS IS besad M ahreddin~ shout 20 wdgh! pa cm! sppfianoaswith the ati huflcs.Figure 1- Process Flows for Recovery of Materials from Shredder ResiduesF&ure 2- Argonne’s Continuous-Polyurethane-FoamWas& Rinse and Dry Process Equipment (3)Figure 3- Cleaned Polyurethane Foam Bales Ready for ShipmentP@ure 4- Headlamp Backcans Produced from 100% Post-consumerABS recovered from Appliance Shredder ResidueACKNOWLEDGEMENTSThis work was sponsored by the U.S. Department of Energy, Assistant Secretary for EnergyEfficiency and Renewable Energy, Office of Industrial technologies, under contract W-31 -109-Eng-38.1.2.3.4,REFERENCESDaniels, E.J., B.J. Jody, and P.V. Bonsignore, “Alternatives for Recycling AutomobileShredder Residue”, The Journal of Resource Mana~ement and Technology, VOI.20,No.1, pp.14-26 (March, 1992).Jody, B. J. and E. J. Daniels, “Automobile Shredder Residue: Treatment Options”,Hazardous Waste & Hazardous Materials, VO1.8,No.3, pp.219-230 (September, 1991).Jody, B., E. Daniels and J. A. Libera, “Efficient Continuous Dryer for FlexiblePolyurethane Foam and Cleaning Apparatus; U.S. Patentj No. 5,882,432, 16 March1999.Jody, B.J. and E.J. Daniels, “Reeovery of Flexible Polyurethane Foam from ShredderResidue; ReDort ANMXUYTM-152, 1999, Argonne National Laboratory.-#’f’ ,L C5. Jody, B.J., B. Arman, D. Karvelas, J. Pomykala and E.J. Daniels, “Method for theSeparation of High Impact Polystyrene (HIPS) and Acrylonitrile Butadiane Styrene(ABS) Plastics: U.S. Patent, No. 5,653,867,5 August 1997.

Materials recovery from shredder residues

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Materials recovery from shredder residues

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