DE29724536U1 - Device for the dry separation of tough elastic materials such as plastics and of materials that shred under mechanical stress such as paper - Google Patents

Description

BOEHMERT & BOEHMERT

LAW FIRM

Bochmert & Boehmert■ POB 1071 27 · D-2K07I Bremen

German Patent and Trademark Office Zweibrückenstr. 80297 Munich

DR.-ING. KARL BOEHMERT.PA (1899-1973) DIPL INC. ALBERT BOEHMERT,PA(1902-1993) WILHELM J. H. STAHLBERG, Attorney-at-Law Bremen DR.-ING. WALTER HOORMANN. PA-. Brew DIPL-PHYS. DR.HEINZGODDAR,PA·,Mönchen DR.-ING. ROLAND LIESEGANG. PA·. Munich WOLF-DIETER KUNTZE. Attorney, Bremen, Alicant« DIPL.-PHYS. ROBERT MÜNZHUBER, PA(193j-1992) DR. LUDWIG KOUKER, RA, Bees DR. (CHEM.) ANDREAS WINKLER, PA·, Bran™ MICHAELA HUTH-DIERIG, RA, Mönchen DIPL.-PHYS. DR. MARION TÖNHARDT, PA·. DassAlorf DR. ANDREAS EBERT-WEIDENFELLER, LAWYER Bremen D1PL.-ING. EVA LIESEGANG, PA·. Munich DR. AXEL NORDEMANN, RA, Berlin DIPL.-PHYS. DR. DOROTHEE WEBER-BRULS, PA·. Franklin DIPL.-PHYS. DR. STEFAN SCHOHE, PA·. Mönchen DR.-ING. MATTHIAS PHILIPP, PA·, Bielefeld DR. MARTIN WIRTZ, RA. Dusseldorf DR. DETMAR SCHÄFER, LAWYER, Bremen DR. IAN BERND NORDEMANN, LL.M., RA, Berlin

PA - Patent Attorney

RA - Attorney at Law/Attomey at Law

• -European Patent Attorney

^A - Brandenburg, admitted to the Higher Regional Court of Brandenburg

⁰ ■ Maine en Law

All those entitled to representation before the European Union,

Proreuio&ü RqxaeOsuon Uic Comwmity Tiwfcnnrk Office, AlictnU PROF. DR. WILHELM NORDEMANN, RA, BRB" DIPL.-PHYS. EDUARD BAUMANN, PA·. Huhenkirchm DR.-ING. GERALD KLÖPSCH, PA·, Dossdilorf DIPL.-ING. HANS W. GROENING, PA·, Mönchen DIPL-[NG SIEGFRIED SCHIRMER, PA·. Bielefeld

DIPL.-PHYS. LORENZ HANEWINKEL, PA·, Paderborn

DIPL-ING. DR. JAN TÖNNIES, PA. RA. Kiel DIPL.-PHYS. CHRISTIAN BIEHL, PA·. Kid DIPL.-PHYS. DR.-ING. UWE MANASSE, PA·. Bremen DR. CHRISTIAN CZYCHOWSKI, RA, Berlin DR. CARL-RICHARD HAARMANN, RA, Mönchen DIPL-PHYS. DR. THOMAS L. BITTNER, PA·. Berlin DR. VOLKER SCHMITZ, RA, Manchen DIPL.-PHYS. CHRISTIAN W. APPELT, PA·, Munich DR. ANKENORDEMANN-SCHIFFEL, RA", Potsdam KERSTIN MAUCH, LL.M., RA, Potsdam DIPL.-BIOL. DR. JAN B. KRAUSS, PA. Some JÜRGEN ALBRECHT. RA. Munich ANKE SIEBOLD, RA, Bremen DR. KLAUS &EEacgr;&Mgr; BRÖCKER, RA. Berlin DR. ANDREAS DUSTMANN, LL.M., RA, Potsdam DIPL.-ING. NILS T. F. SCHMID, PA, Munich

In cooperation with DIPL.-CHEM. DR. HANS ULRJCH MAY. PA·. Munich

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Your ref.

Your letter of

New registration
Utility model branch from EP 97 920 706.5

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D40037(K) Bremen,

9 August 2001

The Green Dot - Duales System Deutschland AG

Frankfurter Strasse 720 -

51145 Cologne

Device for the dry separation of tough elastic materials, such as plastics and rubber, from materials that disintegrate under mechanical stress, such as paper

The invention relates to a device for the dry separation of materials that are tough and elastic at normal temperatures, such as plastics and rubber, from other materials that disintegrate under great mechanical stress, such as paper, cardboard, carton or other products containing cellulose fibers.

Hollerallee 32 · D-2820?

P.OB. {Oyi \1 ■ p«28971 grfrn,en · Jflephoij -34J90; · Tejefax +49-421-3491768

MUNICH - BREMEN - BERLIN - DÜSSELDORF - FRANmjRT4-e*IELlFELD iWSDAM - BBA»JDEMBUr(>-»KIEL - PADERBORN - HÖHENKIRCHEN - ALICANTE

http://www.boehmert.de e-mail: postmaster@boehmert.de

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The separation of plastics and paper is a significant problem, particularly when it comes to waste disposal and the recovery of the materials contained in the waste. Such mixed waste, which contains both plastics and paper or other cellulose products, is generated in large quantities. For example, the pre-sorted plastic packaging from the collections of the dual system, in particular the so-called mixed fraction, contains a not insignificant proportion of paper, which is made up of paper labels, misclassifications during sorting and paper-plastic composite materials.

Until now, plastic, rubber and other tough, elastic materials have been separated from materials containing cellulose fibres, such as paper, cardboard and carton, using a wet separation process by largely dissolving the fibre matrix and then separating it into at least two material streams, namely the cellulose-containing sludge with a high water content and the water-insoluble plastic. This process requires considerable energy and mechanical expenditure. Paper dissolution takes place in a wet mill, for example, where water is added to the shredding process several times the weight of plastic and paper. In particular, the water masses that need to be accelerated require a lot of energy. So-called friction separators are used to separate paper fibres and the resulting sludge made up of fillers, dirt or other substances from the plastic. In any case, the fibre-rich mass stream must then be dewatered, e.g. using vibrating or bottom sieves. In addition, the water content is usually reduced by pressing such as chamber filter presses, although a high water content of more than 50% still remains in the product. If the paper fibre-rich mass cannot be recycled, which is usually the case with waste materials, the high water content either results in high landfill costs or, in the case of thermal use of the waste, considerable drying costs. The plastic, especially if it is rich in films, as is the case with the combination of the frequently occurring polyethylene films with paper, must also be dewatered, which is primarily carried out using mechanical dryers. Modified centrifuges or spin dryers are used for this purpose. Thermal (post-)drying may also be necessary, so that the overall separation costs

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causes considerable costs and is ecologically disadvantageous due to the high energy consumption.

Numerous studies have been carried out on this. Examples include: Louis Jetten, Material plastic recycling and the role of water in processing technology for the recycling of plastics, VDI-Verlag, Düsseldorf, 1993, and Technology study: Material plastic recycling, Part 2, ed. EwvK, Development company for the recycling of plastics, Wiesbaden, 1992.

There are also already processes known for the dry separation of paper and plastics that work using electrostatic charging. One example is the separation in a free-fall separator, which is described in DE 32 27 874 and DE 42 25 977, for example. This process has significant disadvantages. The feed material must meet very specific requirements in terms of geometric dimensions. There are also high requirements for the dryness of the feed material. The operational effort is considerable. In addition, this process cannot be used to separate force-fitting and form-fitting materials.

The object of the invention is therefore to provide an ecologically advantageous, technically simple device for the dry separation of tough elastic materials, such as plastics and rubber, from materials that disintegrate under high mechanical stress, such as paper, cardboard and carton. Examples of plastics are: LDPE, HDPE, polystyrene, PVC, PET and ABS.

It has now surprisingly been found that it is possible to separate tough-elastic materials, such as plastics and rubber, from fibrous materials such as paper in a technically simple manner, essentially in a dry state by subjecting the mixture of plastics and fibrous material to high acceleration and impact forces, whereby the fibrous material tears or frays under the influence of the forces and exits through the corresponding openings of a sieve basket, while the non-fragmented

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The plastic to be separated remains inside the housing and is discharged in the axial direction. The application of acceleration and impact forces or the use of a centrifuge for dry separation of paper and plastic is surprising, since centrifuges have always been used to separate solid-liquid phases or liquid-liquid phases.

The material to be separated is preferably pre-shredded to a size < 50 mm.

The subject of the invention is therefore a device which consists of a closed screen basket which has a polygonal shape in cross-section and has a large number of holes or openings, with a rotatable drive shaft arranged coaxially inside the screen basket, to which blades rigidly connected to the drive shaft are attached. The drive shaft is driven, for example, via a flange with a belt drive with an electric motor (not shown). The blade diameter is dimensioned in such a way that a gap remains between the end of the blade and the housing. The size of the material to be shredded can be varied depending on the geometry.

On the feed side, the first blades in the housing have a smaller diameter than the subsequent blades in order to better distribute the material mixture to be separated in the housing.

The housing and the internal rotating shaft with blades are arranged in a box which has a feed opening for the material mixture to be separated and an outlet opening at the other end for the plastic remaining inside the drum and conveyed by the rotating blades. The box also has an outlet opening for the separated paper. A rotating scraper (not shown) can be provided to improve the separation of the paper.

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The housing is preferably made of a high-strength and corrosion-resistant material such as stainless steel, as are the drive shaft and blades.

The holes or outlets on the periphery of the screen basket preferably have pointed edges (not shown!), which serve to better shred the shredded paper thrown outwards against the screen basket through the hole in the housing, whereby the screen basket is supported by the outer walls of the box.

In order to ensure the movement of the particles in the axial direction with sufficient residence time in the device, the blades are preferably angled, with angles of attack in the range of 5 to 7 degrees being suitable, for example, for the plastic mixed fraction from the dual system.

The internal shaft with blades rotates at speeds in the range of 1000 to 2000, preferably 1200 to 1800 revolutions per minute, whereby the number of revolutions is set depending on the mixture of substances used. The residence time is 10 s to 2 min.

The outlet openings vary in size between 2 and 7 mm depending on the grain size of the feed material and the desired degree of separation.

The shape of the screen basket in cross section is a polygon, which can have isosceles or unequal-sided surfaces. It has been shown that if the screen basket is made up of polygon-like surfaces, the separation effect is significantly better than with a cylindrical screen basket.

The device and its operation are explained by way of example using the attached drawing, where

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Figure 1 shows a longitudinal section through a device according to the invention; and
Figure 2 shows a cross-section along the line AA' of Figure 1.

The mixture of plastic and paper is fed through the feed opening 7 and distributed inside the screen basket by the first blades, which have a smaller diameter than the following blades 4. The shaft 3 with the blades 4, which is set in rotation by a drive (not shown) via the flange 5 with a belt drive, generates an acceleration and an impact of the particles, which ultimately leads to the frayed paper accumulating on the screen basket 1 and then exiting through the holes 2. At the same time, the plastic continues to move in the axial direction and is removed through the outlet opening 8. The paper that accumulates in the space formed by the box 6 and the screen basket 1 is sucked out through the outlet opening 9 by means of a pneumatic suction device (not shown).

A device according to the invention has, for example, the following dimensions: length 1500 mm, blade diameter 950 mm (variable), gap width between blade end and housing wall depending on the shape of the housing: max. 25 mm, number of blades: 4x11, power consumption of the device 50 - 80 kilowatts, outlet openings of the sieve basket: 5 mm, throughput 1

Example

A mixture consists of 90.4% packaging film and 9.6% coating paper. It is crushed using a mill with a sieve basket that has a diameter of 50 mm. The paper is homogeneously distributed in the plastic and the mixture is dry. After the mixture has passed through the device for the first time, the following separation result is obtained:

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Results of the first run:

Good fraction (%) Bad fraction (%) yield 93.5 6.5 Paper content 6.9 47.9 Plastic content 93.1 52.1

A renewed feeding of the good fraction from the result leads to the following separation result:

Results of the second run:

Good fraction (%) Bad fraction (%) yield 96.4 3.6 Paper content 4.5 71.5 Plastic content 95.5 28.5

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In total, 57.6% of the input paper is separated in two passes, resulting in a yield of 90.1%.

Claims (11)

1. Device for the dry separation of viscoelastic materials, such as plastics and rubber, from materials which shred under mechanical stress, in particular paper, comprising a screen basket ( 1 ) which has a substantially cylindrical shape and which has holes or outlets ( 2 ) in a casing for the passage of the shredded material, wherein a rotatable drive shaft ( 3 ) is arranged coaxially in an inner region of the screen basket, on which blades connected to the drive shaft are fastened, characterized in that the blades ( 4 ) apply high radial, axial and tangential acceleration forces and impact forces to the materials to be separated in such a way that only the fibrous material is shredded and separated from the viscoelastic material, wherein the viscoelastic materials are discharged in a substantially uncrushed state in a separate mass flow, while the shredded materials pass through the holes or outlets ( 2 ) of the cross-sectionally polygonally designed sieve basket ( 1 ). 2. Device according to claim 1, characterized in that the rotation speed of the blades ( 4 ) is adjustable in a range of 1000 to 2000 revolutions per minute. 3. Device according to claim 1 or 2, characterized in that the bores or outlets ( 2 ) on an inner side of the sieve basket ( 1 ) have sharp edges to reinforce the defibration effect. 4. Device according to one of claims 1 to 3, characterized in that the blades ( 4 ) are rigidly connected to the drive shaft ( 3 ). 4. Device according to one of claims 1 to 4, characterized in that the blades ( 4 ) are positioned relative to the drive shaft ( 3 ). 6. Device according to one of claims 1 to 5, characterized in that the blades ( 4 ) are attached to the drive shaft ( 3 ) at an angle of attack of 5 to 7 degrees. 7. Device according to one of claims 1 to 6, characterized in that the blades ( 4 ) on the feed side have a smaller diameter than the following blades. 8. Device according to one of claims 1 to 7, characterized in that the blades ( 4 ) are arranged on the drive shaft ( 3 ) in such a way that a gap is present between the blade end and the housing wall. 9. Device according to one of claims 1 to 8, characterized in that the housing ( 1 ) with internal drive shaft ( 3 ) and blades ( 4 ) are arranged in a box ( 6 ) which has an inlet opening ( 7 ) for the mixture to be separated on the feed side and an outlet opening ( 8 ) at the other end for the plastic remaining inside the drum and conveyed by the rotating blades. 10. Device according to one of claims 1 to 9, characterized in that the housing ( 1 ) with internal drive shaft ( 3 ) is arranged horizontally. 11. Device according to one of claims 1 to 10, characterized in that the outlet openings or bores ( 2 ) have a diameter between 2 and 7 mm.