DE10206263A1 - Process for dry processing of mixed waste containing plastic and possibly metallic materials to which foreign substances adhere - Google Patents

Abstract

A process for the dry processing of mixed waste, which contains plastic and possibly metallic materials to which foreign substances adhere, is characterized in that the mixed waste in a state in which the foreign substances are at least partially exposed, radial, axial and tangential impulse forces with minimized entry is subjected to thermal energy, foreign substances being drawn off separately from the plastic or the metallic materials in a mass flow and in particular pasty, greasy / oily substances being bound by absorbers.

Description

The invention relates to a method for dry processing of mixed waste, which in particular plastic and possibly metallic materials on which foreign substances cling, contain, for example pasty material and / or oily, greasy, moist or dried residues and possibly also metallic and / or paper-containing foils, Plastic films or film composites. The plastic can be more or less intrinsically stable structures and also as a film.

Plastic films or film composites. The plastic can be more or less intrinsically stable structures and also as a film.

It is common, for example, dairy products where the expiration date has passed is to take it off the shelf and dispose of it. The problem of disposal arises also for wrong productions. Many of these dairy products, such as yogurt, curd cheese, pudding, are filled in plastic cups or plastic trays, mostly made of polypropylene (PP) or Polystyrene (PS) exist. These cups are closed with a lid, for example made of aluminum. Depending on the product or manufacturer, however, Composite materials used as sealing caps, for example made of a polyethylene (PE) - or Polyethylene terephthalate (PET) film and a vapor-deposited aluminum layer. Manufacturers often use both types of lids. When processing ("Recycling") of batches or returns is the goal of the contents of the packaging to be squeezed out and used as animal feed, for example. Basically, however, also pose the plastics and also the aluminum represent valuable fractions that are equally should be recovered. Although the containers are pre-compressed during recycling, about 5-50% of the content remains in or on the packaging. If the The pasty products and packaging must be reused Residues are removed as completely as possible, which is usually a costly washing and Water treatment process requires.

The lid not only has the task of protecting the product, it is at the same time Advertising medium and is therefore sometimes printed elaborately. For promotional reasons, many contain the Plastic container also has a printed sleeve, which is made of paper, however can also consist of plastic film.

Problems similar to those described above can also be seen with the Recycling of incompletely emptied silicone cartridges with dried residues, also for toothpaste dispensers and toothpaste tubes, in which the container is made of polyethylene or polypropylene. Other pasty, moist, oily or greasy residues that on Plastic cling to the packaging, often deteriorate the quality of the plastic in a degree that the processing of the plastic for new applications strong is restricted. This also applies to margarine cups, disposable dishes and - cutlery and the like.

In the future, it is conceivable that other plastics than the packaging material used above, for example polyethylene terephthalate (PET) or like.

DE 41 20 111 A1 describes a method for cleaning contaminated plastics in the field of plastic recycling through the use of decanters, especially Sieve decanters known, with the liquid, pasty and also other adhering to the plastic Contaminants can largely be removed without wet washing. The separation takes place thereby by the centrifugal field generated in the decanter, whereby to improve the Separation effect in the same process step the plastic is brushed. The brush elements provide at the same time for the transport of the material.

A cleaning device that works on a similar principle is the subject of DE 92 11 176 U1, according to which a helical brush roller is arranged so that it is rotates in a stationary sieve tube. The brought in to be cleaned Plastic materials roll practically between the sieve tube and the brush roller, whereby adhering dirt is brushed off on all sides. An inner rough surface of the sieve tube prevents the plastics to be cleaned from sliding easily.

DE 196 08 703 A1 discloses, by exerting a shear impact force on crushed Plastic pieces to separate the adhering foreign bodies. The shear impact force is determined by paired fixed or movable bolts that produce what is to be cleaned Polish and sort and adjust the size of the plastic material between them.

The described processes and systems have in common that the adhering foreign substances can be removed by frictional contact with the machine elements. Especially with yourself decomposing foods, such as dairy products, this raises serious hygienic problems, so that brush or bolt cleaners are regularly rinsed and may need to be disinfected to prevent contamination. Furthermore These procedures cause problems when the adherent substances include oils or fats as well Contain lactic acids. These substances remain both on the surface of the machine elements as well adhere to the product to be cleaned (plastic, aluminum, etc.), which in considerable Measurements of an undesirable contamination of the machine and product with germ contamination leads. In addition, such dirt is also carried over otherwise clean parts.

It is an object of the present invention to provide a dry working method of to provide the type mentioned at the beginning with which the undesired ingredients, especially pasty, moist, oily or greasy materials, clean of the rest of the mixed waste can be separated without energetically unfavorable measures such as washing, must be used. Also, for example, relatively firmly adhering lid material should Abdominal cuffs and labels and the like can be detachable at the same time in a dry manner.

According to the invention, this object is achieved in that the mixed waste in a state in which the foreign substances are at least partially exposed, radial, axial and tangential Impulse forces are subjected, the foreign matter from the plastic or metallic materials mechanically separated and discharged in different mass flows become. It has thus surprisingly been found that dry mechanical cleaning succeeds if you consider the sluggish behavior of the remaining content materials, especially with pasty masses, appropriately exploited. The impulse forces can, for example, by themselves in the process self-cleaning blades or bats can be applied. It becomes comparative little energy entered, which is significantly lower than conventional ones Cutting mills so that little losses occur, for example due to frictional energy.

To support the separation, especially of greasy, oily or other moist These substances are bound by an absorbent auxiliary. As an absorber hydrophilic and lipophilic materials are possible. Examples of suitable absorbers are Paper, cellulose, diaper production waste, cellulose-containing hygiene articles and the like, which often also contain superabsorbent substances, moisture tie to a particularly large extent. Wood sanding and wood dust are also suitable. Chalk and mineral oil binders are also suitable. In the sense of protecting A "second recycling material" is preferably used for environmental resources, such as recycling Paper or the production waste mentioned above, is also conceivable, finely ground To use polyurethane (PU) foam, which is incurred in the disposal of refrigerators is.

The type and amount of absorber are determined according to the properties of the items to be cleaned Mixed waste and the goods to be bound. For example, it may be necessary to For cleaning foils, use other absorbers than for cleaning cup material.

The mixed waste is preferably comminuted, for example the Food packaging, silicone cartridges or toothpaste dispenser, so that pasty and dried Material stands out from the plastic as freely as possible and can be easily discharged.

It is also preferred to add the absorber before the pre-comminution. As an absorber for Oil or fat binding is used, for example, by chalk. Often, the ones to be processed Plastic packaging also delivered, for example, mixed with carrier cardboard boxes can also serve as an absorber. So it is generally not necessary to do this Cardboard boxes can be taken from the material flow to be processed before shredding, it is because they have already lost their ability to bind due to leaking ingredients.

The remaining mixed waste stream freed from foreign substances is further preferred for Remove the remaining residual moisture. This is an important process step when it comes to aluminum-lidded cups or bowls in subsequent ones Steps as described below.

It is namely possible to use the lid made of a mixture of paper and plastic Aluminum vapor deposition, as used by various manufacturers, by means of a wind sifting remove. The drier the material, the better this will be.

The aluminum covers, however, can be electrostatically or by means of eddy currents deposit. Spherical aluminum, which may come from the lids, will also be the same away. Dryness of both plastic and aluminum improves here also the sorting result.

The types of plastic can also be separated from one another by means of electrostatic deposition be separated as these have different electrostatic behavior and different Have surface charges.

It is therefore provided in a particularly preferred embodiment of the invention that the Residual mixed waste stream freed of foreign matter and optionally dried is subjected to at least one at least one-stage electrostatic deposition, the electrostatic conditions can be adjusted so that metals and individual Plastic types are deducted from the mass flow in succession.

The method according to the invention can be used by using a horizontal one Sieve basket for surface cleaning of the plastic product or, if applicable, the metallic components such as aluminum lids. The strainer basket is cylindrical or polygonal in cross section, with a rotatable inside the strainer Drive shaft is arranged, on which preferably rigid with the drive shaft connected blades are attached, the mixed waste in a state in which the Foreign substances are at least partially exposed, in particular the necessary ones from the blades experienced radial, axial and tangential impulse forces and the foreign matter through the Exit openings in the strainer basket. Such a strainer is already known from DE 196 16 623 A1 known and is used there to composite paper and plastic to unlock dry mechanically. It is surprising that this screen basket is unmodified can also be used to achieve the object on which the invention is based.

Those emerging from mechanical cleaning, in the sense of the invention expediently bound by absorbers pasty, greasy or oily residues are advantageous with transported away by a screw conveyor. It is usually also necessary to use the strainer basket To provide a device for mechanical cleaning with a scraper so that material that has passed through the openings of the screen basket can be removed. The Scraper device can be a scraper device running around the outside of the screen basket. Also Blowing off the remains is conceivable.

If this screen basket is used, continuous process control is also possible.

If the cleaning result is not satisfactory, the mechanical cleaning an additional conventional surface cleaning can be carried out for example by a brush cleaner known per se. Because the critical foreign matter have already been largely removed, the brush cleaner is only a few Remove residual and contaminants. With this dry mechanical post-cleaning predominantly the unwanted substances bound by the absorber from the surface away.

With the method according to the invention, the materials to be cleaned become only one exposed to mechanical stress, which is nevertheless too excellent cleaned plastics and metals. Wet processes do not only stress the plastic mechanically, but also thermally and in particular chemically and can affect the quality of the Plastic deteriorate sustainably. For example, there are often lactic acids Food residues in the wash water, which attack polystyrene (PS) in such a way that the material becomes brittle and is therefore no longer suitable for many applications. In which The procedure according to the invention is the use properties of the polystyrene through the Elimination of the washing step improved so much that the bendability is retained.

The plastics cleaned according to the procedure according to the invention can now be used without further intermediate stages, for example melted in an extruder and turned into granules are processed. The heat in the extruder occurs because of the minimal Adhesions of dairy products or oils and fats still have vapors, but they do vacuum degassing of the melt can be deducted. Maybe still existing organic or inorganic admixtures, such as paper and on the other hand, aluminum, through filters or other separation systems installed in the extruder head discharged from the melt. The result is a soiled out dry way Packaging plastic waste obtained clean plastic granules, which because of the elimination of the complete wet processing is also particularly inexpensive to manufacture. Such Inexpensive granules are therefore particularly suitable for mass applications for single-use products etc.

Typical applications, for example for such polystyrene Granules are flower pots, transport boxes, screw boxes, pallets for flower pots and the same.

It is also conceivable that cleaned unsorted according to the inventive method To process plastic mixture to agglomerate, this for example in one Pot agglomerator, a pelletizer or a disc agglomerator superficially is melted, so that the plastics with formation of a particle with jagged Glue the surface (agglomerate).

It has already been mentioned in the introduction that the method according to the invention is also intended to clean, especially degrease, foils. Here is one Possibility of packaging foils for sausage, cheese and the like, shopping bags, etc. treat and rid of foreign matter in such a way that a Odor nuisance due to decomposing biological materials is greatly reduced.

The invention will be explained in more detail below with reference to the drawing. It shows:

Figure 1 is a flow diagram for a method according to the present invention according to a first embodiment, which is suitable for example for milk product waste.

Fig. 2 is a flow chart of an extended and modified the method of the invention according to a further embodiment; and

Fig. 3 is a flow diagram of another embodiment of the method according to the invention.

The method, as shown in FIG. 1, begins with the pre-compression and, if necessary, with the pre-comminution 10 of the feed material, for example polystyrene beakers still filled with milk product, which are closed with an aluminum lid. The pasty material and other adhesions are largely exposed due to the pre-compression or pre-crushing, the aluminum lids are largely separated from the cups and form aluminum pieces or aluminum flakes. The material pretreated in this way then passes into the mechanical cleaning unit 20 , where it is exposed to the generally very high radial, tangential and axial impulse forces. The bound material is thrown against the walls of the screen basket according to DE 196 16 623 A1 and exits while the plastic pieces and aluminum parts remain in the screen basket and are carried on to the next process stage 30 , drying. The drying serves to prepare for the subsequent electrostatic deposition 40 , for example by means of a roller separator of the "corona" type, in which the aluminum is drawn off from the mass flow. If necessary, post-cleaning 50 can also be carried out, for example a wind sifting. Eddy current separation can also be used instead of electrostatic separation.

A simplified process, which includes the steps of pre-comminution 10 , mechanical cleaning 20 and optionally drying 30 , can be used to prepare silicone cartridges, toothpaste dispensers and the like.

If there is more than one type of plastic in the mixed waste, for example polypropylene or polypropylene or polyethylene terephthalate in addition to polystyrene, additional electrical separation stages can be provided in order to separate these types of plastic. This is explained in connection with FIG. 2, which shows a flow diagram for a method according to the invention, with which a milk product cup fraction can be treated with aluminum lids and paper-plastic lids. First, as in the process control according to FIG. 1, a preliminary comminution 10 is carried out, followed by mechanical cleaning 20 , the pasty material being drawn off from the mass flow. The remaining mass flow, which contains plastics and lids, is dried in stage 30 . It has been shown that in the mechanical cleaning 20 the light paper PET lids with aluminum vapor deposition and also the belly bands and belly foils are removed from the cups, so that they can be removed in a wind classifier 50 provided after the drying stage 30 . The aluminum material is then pulled out in the electrostatic deposition 40 . Basically, it is possible to swap stages 40 and 50 in this process run, the process management will be optimized based on the expected composition of the feed material. After the covers have been removed from the mass flow, the types of plastics are separated, an additional electrostatic or triboelectric separation stage 42 being provided for two types of plastics present, in which a selective, different charging of the different plastics is effected by triboelectric effects. If several types of plastic are to be separated, additional electrostatic separation stages can be used e.g. B. 44 are connected, gradually, as indicated by arrow 46 , the individual types of plastic are taken out of the mass flow.

FIG. 3 shows a further flow diagram, with which a particularly preferred embodiment of the invention is to be illustrated, in which the process sequences are further optimized.

First, packagings with residual ingredients, which may be pasty or solid, are fed to the pressing 5 , and pressed ingredients can continue to be used. For example, dairy products are still used in the animal feed industry. The compressed material then passes into the pre-comminution 10 , preferably with the addition of an absorber for binding fats, for example chalk or the like, present in the product. The amount of absorber required depends on the type of absorber and its absorption capacity for fats, oils and liquids, as well as the amount to be bound. It is ideal to dose the absorber, for example, in a screw conveyor, so that there is intensive contact with pasty, oily or greasy soiling. Kneading and mechanical mixing allow the absorber to bind the unwanted residue. The mechanical cleaning 20 then takes place according to the procedure according to the invention. If the moisture content of the mass flow is too high, paper or cellulose can be added. The cardboard boxes used as outer packaging, other recycling material, textile materials and product waste from the manufacture of diapers and other sanitary articles, in particular those containing so-called superabsorbers, are also suitable here. From the mechanical cleaning 20 , the fats or pasty residues bound by absorbers emerge as a largely dry product, optionally also paper fibers and other. The mechanically cleaned material is now optionally dehumidified in a dry centrifuge or a dryer 30 . A comminution 35 can expediently take place if an additional surface cleaning 38 or a further material digestion is planned. Here again, the addition of an absorber is useful, for example chalk to bind fats. The surface cleaning 38 can be a dry mechanical brushing process in which the last residues and contaminants are removed. The separation 40 from aluminum and similar metals and composites, which has already been described further in connection with FIGS. 1 and 2, is then carried out, for example, by means of an eddy current separator or an electrostatic separator. Downstream triboelectric isolators, which can be one or more stages, provide the plastic separation into individual types and form electrostatic separation stages 42 .

The pasty, exiting from mechanical cleaning, bound by absorbers, oily or greasy residues are conveniently with a screw conveyor removed. It is usually also necessary to use the screen basket of the device for mechanical To provide cleaning with a scraper so that the possibly adhering bound pasty material can be removed. The scraper device can be on the outside the screen basket running scraper device or a blow-off device.

The in the above description, in the drawing and in the claims Disclosed features of the invention can be used both individually and in any combination the realization of the invention may be essential.

Claims (14)

1. A method for dry processing of mixed waste, which contain plastic and possibly metallic materials to which foreign substances adhere, characterized in that the mixed waste in a state in which foreign substances are at least partially exposed, radial, axial and tangential impulse forces with minimized partially exposed , radial, axial and tangential impulse forces with minimized input of thermal energy, the foreign substances being separated from the plastic and possibly the metallic materials in different mass flows. 2. The method according to claim 1, characterized in that the mixed waste is comminuted become. 3. The method according to claim 2, characterized in that the pre-shredding under At least one absorber is added, which is pasty, greasy, oily materials and / or moisture binds. 4. The method according to any one of claims 1 to 3, characterized in that as an absorber Paper, cellulose or cellulose-like substances, such as wood pulp or wood dust, textile Materials, production waste of hygiene articles, possibly with superabsorbers, ground polyurethane foam or the like and mixtures of these substances is used. 5. The method according to any one of claims 1 to 4, characterized in that the of Foreign substances freed the remaining mixed waste stream to remove the remaining ones Residual moisture is dried. 6. The method according to any one of claims 1 to 5, characterized in that the of Foreign material freed and possibly dried residual mixed waste stream one Is subjected to wind sifting. 7. The method according to any one of claims 1 to 5, characterized in that the of Residual mixed waste stream freed of foreign matter and possibly dried at least one at least one-stage electrostatic or triboelectric deposition and / or subjected to an eddy current decision. 8. The method according to any one of claims 1 to 7, characterized in that before electrostatic deposition or eddy current deposition the surfaces of the rest Mixed waste stream can be brushed dry mechanically. 9. Use of a horizontal strainer basket, which is cylindrical or in Cross-section has a polygonal shape, with a rotatable inside the screen basket Drive shaft is arranged, on which preferably rigid with the drive shaft connected blades are attached for dry processing of mixed waste, which Plastic and possibly metallic materials, on which foreign substances adhere, included, the mixed waste in a state in which the foreign matter at least partially exposed, subject to radial, axial and tangential impulse forces and the foreign substances emerge through the openings in the strainer basket. 10. Use according to claim 9 for the continuous dry processing of Mixed waste, which plastic and possibly metallic materials, on which pasty, greasy or oily material adhered, included, with the addition of a hydrophilic or lipophilic absorber is used. 11. Use according to claim 10, wherein the or absorber by means of a metering screw be entered. 12. Use according to one of claims 9 to 11, wherein a stripping device for Removal of the material passed through the openings of the screen basket is provided. 13. Use according to claim 12, characterized in that the stripping device a scraper device or a blow-off device running around the outside of the screen basket is. 14. Use according to claim 9, wherein a screw conveyor for removing the discharged foreign matter material is provided.