DE19651571A1 - Recycling process treating wastes, plastic mixtures and plastic composites - Google Patents

Abstract

This new recycling process treats wastes, plastic mixtures and plastic composites. The mixed plastics and composites are separated by type, leaving other residual materials. The sorted plastic or plastic mixture undergoes wet treatment to clean the surfaces. An extractant removes soluble components of the plastics. Preferably the plastic mixture comprises polypropylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, low density polyethylene, high density polyethylene and polyurethane. The composites include metals and/or thermally-useful residues and one or more of the plastics above. Composites are separated before the wet treatment, into plastic components, residual materials and if appropriate, metallic components. The sorted plastics are dried after wet treatment. The plastic or plastic mixture is size reduced before wet treatment. Water is used in wet treatment; extraction employs a halogen- and aromatic-free substance, especially ethyl acetate. Any extractant residues left adhering to the plastic, are removed by water or heating. The plastic is extruded and granulated after extraction. Composite materials comprise packing, electronic scrap, aluminium composites, or scrap cable. Plastic mixture comprises hollow ware, sheets and other plastic objects.

Description

The invention relates to a recycling process for waste preparation, plastic mixtures and art Composite materials included.

In the German Waste Act, the obligation to recycle waste is anchored, the so-called waste recovery requirement. Accordingly, waste recycling, ie the extraction of substances or energy from waste, has priority over other disposal if

• - recycling is technically possible,
• - The resulting additional costs compared to other procedures are not unreasonable and
• - for the substances obtained or for the energy obtained there is a market.

Waste recycling enables multiple uses of substances saving primary raw materials or the saving of primary energy sources. A special Attention is paid to recycling when recycling waste directed by plastics. In the case where art that supplies waste by type Recycling only minor problems, since at least the thermopla plastic materials in this case relatively can be prepared by extrusion and granulation. The recycling of plastic waste becomes problematic then when these as plastic mixtures or as a composite materials are delivered. Typical plastic mixtures can be found in household waste, for example the "Dual System Germany" (DSD) are sorted. The The plastic fraction contains a wide variety of mate materials such as polystyrene, polypropylene, Po lyethylene and its compounds, which are processed without a cannot be fed for further use.  

Since the plastic mixtures that have arisen at the DSD so far practically not to the desired extent in the individual components can be separated, procedures have been carried out in recent years ren to improve the thermal recovery of such Waste developed further. Such approaches are however probably from an ecological as well as an economic point of view partial, because valuable raw materials are lost and a large most of the internal energy remains unused.

Great progress has been made in the past few years mechanical recycling of polyolefin plastics targets, such as those used for packaging will. In particular the processing of foils and hollow body fractions could be improved, so that as an end course product practically pure, high-quality plastic materials can be made available.

A problem with the processing of plastic waste len, especially of non-sorted plastic waste len, the predominant part of packaging stem from the fact that Ver cling to impurities. These contaminants can for example in containers from the product or from the Outside diffused pollutants originate. The white Such packaging is often printed, so that the printing inks must also be removed.

To remove such impurities, übli wet processing systems where the Plastic waste to be treated with water. At the on preparation is a multi-stage water purification systems used. The recyclate points to this However, wet processing has a very unpleasant smell and an indefinable color and is therefore only in one limited use still possible. I.e. the application rich of such recyclates is limited to goods to which  only minimal quality requirements are made - for example garbage bags, park benches, containers, clothes hangers gel, etc. In these cases, new material is often required and other fillers are added to make up the to be able to meet low quality requirements.

Extracts were used as an alternative to the wet preparation ons process where cleaning instead by water through a CFC and aromatic-free extraction medium done. Such a method is for example known as NOREC. The application of this procedure rens is on thin-walled packaging made of polyethylene and Polypropylene and thin-walled plastic packaging made of Po lyolephins limited.

As advantages of the NOREC process over the forth Conventional wet processing with water becomes an essential lower energy consumption and better cleaning efficiency called kung.

However, the cleaning procedures above will only for practically sorted plastic compos used. So far there is no recycling process known with the Ab containing several types of plastic cases can be processed such that a recyclate is obtained, that with regard to the material properties practically corresponds to a new product.

The invention is therefore based on the object, a Re to create cycling process that with minimal process technical effort a simple treatment of waste len allows that contain several types of plastic.

This object is achieved by the features of claim ches 1 solved.  

By the measure, the plastic waste initially wet processing and a mechanical separation step to undergo and the wet processed and mechanically ge then separated fractions in an extractor with egg nem extractant succeeds, the Mixed plastics and composite materials Separate plastics that have practically no mess more inclinations. Through the series connection of wet processing and extraction, the process engineering African effort to carry out the extraction and thus the amount of extractant is reduced to a minimum be, so that all from an environmental point of view existing requirements are satisfied.

The method according to the invention is particularly advantageous is applicable to waste, the plastics from the group PP, PET, PVC, PS, LDPE, HDPE and PUR, metals like Fe and Al and / or contain thermally usable residues.

In the event that the waste ent hold, these will be advantageous before Naßaufbe riding in the plastic components and the other Ma materials separated. For such a separation an ultrasonic separation process is particularly advantageous use in which the composite materials have a high loading acceleration are exposed.

The wet preparation can before the actual mechani separation of the plastic mixtures into the individual ones Fractions. However, it is also possible that the Plastic mixtures first separated and then wet be subjected to preparation.

Wet processing is particularly effective when the Plastic mixtures or the previously separated single-variety Plastic fractions crushed before wet processing  be, so that a maximum specific surface for Is made available.

The wet preparation was preferably carried out with water, that to temperatures between 60 to 95 ° C, preferably 90 ° C is brought. The extraction is done with a CFC and aromatic-free extractants, for example ethyl lacetate.

That after the extraction step on single-variety art Extractant adhering to the substance is removed by water or separated by a thermal treatment and extracted tion process.

The wet processing and extraction step cleaned plastic fraction is preferred homogenized by extrusion and granulation and in egg brought into a transportable and salable condition.

In the event that the waste is also sorted Contains plastic fraction, this can be bypassed Wet processing step after shredding directly Extraction step are fed.

Other advantageous developments of the invention are the subject of further subclaims.

Preferred embodiments of the invention are in following explained with reference to schematic drawings. Show it:

Fig. 1 is a flowchart of a recycling process according to the invention and

Fig. 2 is a flow diagram of a mechanical separation, which is alternatively used in the recycling process according to the invention.

As already described at the beginning, the in plastic or industrial waste fe, for example packaging films, hollow bodies (bottles, Containers, etc.) and composite materials made of plastics and other materials (metal, compounds, etc.) in the following Composites called, not clean and pure for ab case processing system delivered. Even after the "Dual System Germany" (DSD) delivered waste are usually neither cleaned nor sorted, so that considerable efforts to process the valuable materials are required.

By the method according to the invention, the above-mentioned composite materials (packaging, electronic waste, Cable residues, etc.), hollow body mixtures, foil mixtures, son Other plastic mixtures as well as unmixed films, types pure hollow bodies and unmixed plastic waste from Ge advertising and industry are prepared.

The preparation is comparatively simple of single-variety foils, hollow bodies and plastic waste, which are separated by type of plastic (e.g. polypropy len (PP), polyethylene glycol terephthalate (PET), Po lyvinylchloride (PVC), polysterol (PS), polyethylene low low density (LDPE), high density polyethylene (HDPE) and Po lyurethan (PUR) to a shredding step in which the plastics ge to a predetermined size be brought. After the crushing step, the over Shredders or cutting mills can be done, these are Plastic by type as a shredded film or art pieces of fabric with a maximum diameter of about 3 cm. This crushed, single-variety fraction is in between store saved. The intermediate storage can for example se through plastic silos.  

The non-sorted components of the supplied plastic-containing waste, ie the composites, hollow body, film and plastic mixtures are first mechanically separated and separated according to FIG. 1 (step 1), then or previously subjected to wet processing (step 2) and in In a final cleaning step, the soluble components are dissolved using a suitable extraction agent (step 3).

The mechanical / physical separation can be done in a variety of ways. 1 egg ne mechanical off and separation is only an example in Fig. Indicated in the delivered composites and plastic mixtures, first egg ner manual sorting are fed to the pre-sorting. For this purpose, the delivered material is applied to a conveyor belt and sorted by hand, so that a rough sorting into organic components, thermally usable materials, thermoplastic mixtures, composites and metal takes place.

The organic materials can, for example, in a bioreactor can be processed into methane gas is then usable for energy recovery.

The economically usable materials, as with for example those made of sorted metals and the thermal ones usable goods are separated and marketed leads. The resulting residues for which there is no market is present and which are also not biodegradable, are disposed of, whereby in principle a deposit on egg ner landfill or thermal recovery in question men.

After the first pre-sorting, the remaining Ab waste stream of a largely automated mechani fed separation in which the material flow into its Individual components is separated.  

In Fig. 2 an example of such a mechanical / physical separation is shown. The pre-sorted plastic mixtures, which, depending on the type of waste, can still be mixed with glass, wood, cardboard, organic materials and metals (Al, Cu, Cr-Ni, Pb, steel, etc.) that were not sorted out during pre-sorting first with a shredder and / or a cutting mill (before crushed and brought to a predetermined size. As with the pure-supplied materials, this predetermined size can be limited, for example, to a maximum diameter of 3 cm.

The aforementioned shredders and cutting or shearing mills are used for crushing soft, elastic and tough materials and are well known from the prior art, so that a detailed description of the device used can be dispensed with here for the sake of simplicity. The same applies in principle to the other apparatus used for the procedural steps described below, so that a description of the essential features of the apparatus and equipment used can be limited. After shredding, the material flow can be stored temporarily ( Fig. 2) or taken directly to the next processing step.

According to FIG. 2, the pre-sorted material flow after the comminution and, if appropriate, the intermediate storage is guided past a magnetic separator, via which magnetic components, such as iron, are separated. For this purpose, for example, a magnetic drum separator can be used, in which the material stream to be separated is placed on a shaker chute on which the parts are evenly distributed. The material flow is carried out in a separating drum, which contains a fixed electromagnet, which acts only on a partial area of the drum. The non-magnetizable parts experience no force from the electromagnet and are further promoted. The magnetizable parts are attracted to the electromagnet and adhere to the rotating roller. At the bottom of the roller, the attraction of the magnet decreases and the magnetizable substances fall under the effect of their own weight into a collection container or onto another conveyor belt. Of course, other magnetic separators can also be used, which should preferably act continuously.

Especially when the material flow to be separated Composite materials, such as plastic compound, Contains electronic waste, cable residues, etc. at mechanical separation another process step is pre see in which the composites are separated so that the Plastic components of the composite materials from son other materials.

One can, for example, to separate the composites the comminuted substances of a comparatively high loading expose acceleration by which the adhesive forces over wounds and thus the composite material in its original area components is separated. Such a high particle acceleration can, for example, by ultrasound Separators - so-called accelerators in which the material flow to be separated with Ultra sound is applied. Through this ultrasound Compounding will be both the plastic compo and as well as those with metallic materials Compounds separated so far that the thermoplastic Plastic components in a further process step can be mechanically processed.

To separate the other components (metals, duro plastic plastics, glass, wood, cardboard, organic mate rialien, etc.) from the thermoplastic components  the material flow one or more classification steps fed. A pre-classification can, for example by screening or sifting. Such a sighting can be used to separate pebbles with grain sizes of several ren micrometers (µm) up to 5 mm.

The classification by views is based on the below different large air resistance different sized part in an air stream. The sighting can, for example in a cross-flow classifier, in which the air flow runs across the material flow. Of course, too other types of classifiers, such as zigzag Classifiers or spreading plate classifiers can be used.

By sifting components with one specific gravity that differs significantly from those of plastic materials differ reliably divorce. Such substances are, for example, glass, wood, Paper / cardboard, organic materials and the aforesaid Metals. These substances are depending on their spe specific weight separately and total in own containers melt. Since these materials are valuable, they can be used for further use.

Sifting fails when materials with approximately the same density are contained in the material flow. Such material pairings are, for example, PP, PET; PVC, PS; LDPE, HDPE; Al, PUR. This means that the material flow can only be divided into a few subgroups (heavy fraction, light fraction) by one-time wind sifting, each of which contains the aforementioned material pairings. In difficult substance mixtures, sifting is combined with a large number of types of plastic with sieving steps, which may in turn be followed by sifting. In Fig. 2, the screening step is shown following the screening step - this simplified te illustration also includes several alternating viewing and screening steps, which may be required for the separation.

Read through a screening step before or after sifting coarse materials (cardboard, etc.) can be removed relatively easily nen. The screen residue can then again be viewed be further separated.

The separation into the individual components must therefore by combining it with another process step consequences. This can be done, for example, by combining it with egg sieve classification. Through so-called Fine screen separators in combination with classifiers or accelerators, the components of a group, for example PP and PET, separated and then sorted by type nem appropriate storage, for example a silo be performed. Due to the mechanical / physical separation can also be a separation of aluminum, which in aluminum Plastic composite material is included, of which art material with approximately the same density, for example PUR take place, so that a pure separation of Al is feasible.

After passing through the screening devices, the given if necessary again together with classifiers and accelerators the sorted components (PP, PET, PVC, PS, LDPE, HDPE, PUR and Al) in silos and temporarily stored.

The individual system components, i.e. H. Shredder, Cutting mills, magnetic separators, ultrasonic separators tion (accelerators), classifiers and screening devices each run as a closed system and are included Operated under vacuum. To control the dust explosion the hazardous areas are pressure shock proof or designed to relieve pressure.  

The resulting Me after mechanical separation talle (aluminum, iron, etc.) - as with the Pre-sorting - sold and the unusable rest substances deposited or recycled thermally.

In addition to mechanical separation, the single-variety thermoplastics are subjected to wet processing. In which the mechanical separation representative flow chart of Fig. 2 occurs, the wet processing after the separation into the thermoplastic components.

However, the wet preparation can also be done before the mechani separation step or between the sub-steps (Shredding and separation) of the separation step gene, so that a thermoplastic mixture wet processing passes through and only then mechanically separated becomes. In this variant, however, it takes place before the wet processing a composite separation, in which the compound de in thermoplastics and other materials (metals and other residues) are separated. With this ver The bundle separation step becomes the Ultra described above sound isolation (accelerator) used to the plastic to separate fe from other materials.

Depending on the procedure, the pure plastic components (mechanical separation according to FIG. 2) or the thermoplastic mixtures obtained after the sorting system and the composite separation are subjected to wet processing in which the surfaces of the substances or mixtures are cleaned.

Water is preferably used as the cleaning medium used at a temperature between 60 and 95 ° C, is preferably heated to about 90 ° C. Through these wet conditions dirt will adhere to the surface genes, digests, organic components, residues (at Containers, for example, the residues of the absorbed  Good) and possibly inks removed. The Nassauf Preparation can be done in two stages with different water temperatures or water pressures.

In the case where the plastic mixtures are pre-cleaned, the mechanical separation takes place only afterwards, as indicated in FIG. 2. With this procedure, however, the thermoplastic mixtures are brought to the predetermined grain size via shredders / cutting mills before wet processing.

As can also be seen in FIG. 1, wet processing can be dispensed with for types of purely delivered plastics, so that these plastics can be stored in the silos directly after the shredding step (shredder / cutting mill). If the composites are not dirty, they can be processed without wet processing.

The wet-processed, sorted plastics can then collected in interim storage facilities.

After mechanical separation (step 1) and wet preparation (step 2) of the thermoplastic Ingredients, these are separated according to type a wide Ren cleaning step (step 3) supplied. In this who the soluble components of the plastic particles (Plastic chips) through a CFC and aromatic-free Ex traction agent, for example ethyl acetate removed. Here can also be filled from inside and through Environmental conditions substances diffused from outside, especially odorants are removed. Furthermore can during the pretreatment steps described above Polymers degraded to waxy substances, which can be found in the polymer matrix had accumulated. According to this procedure it is therefore possible to send the Mineral and greasy Ver  remove dirt as well as networked printing inks. Of other migration-capable ingredients are identified solves.

As mentioned at the beginning, the extraction process is as already known as the NOREC method.

The extraction takes place in a carousel extractor, in which is carried out a multi-stage extraction. With egg Such carousel extractor is in one fixed round trough with slot bottom a cellular wheel, the turns slowly. This cellular wheel is in ge from each other divided cells into which the extraction material, i. H. the pure plastics are filled. The extra material slowly rotates with the cell wheel and is sprinkled with solvent during the circulation. The It seeps through the extraction material, solves the pre-described components and flows through the bottom of the slot floor in a drip pan. After the extraction material is one Rotated the cell wheel and turned out leached, it falls through an opening in the fixed Slit arch from the extractor.

In such a carousel arrangement, the Zel len of the cellular wheel continuously with fresh extracti filled and fall after a cell wheel rotation continuously down out. The extractant is also fed continuously and runs with Ex tracts loaded continuously. The solvent will be there in countercurrent to the circulating extraction material.

Through this extraction step, the aforementioned Contaminants detached and with the extractant (Ethyl acetate) removed.

The loaded extractant is then aufbe rides, for example by heating to a tem  temperature above the boiling point of the extractant the latter evaporates and thus thermally from the residues is separated. The subsequently condensed extraction medium can again be continuous and almost lossless be fed to the extraction process. The thermally abge separated residues are then disposed of (landfill, thermal recovery).

The extract that adheres to the pure plastics agent is rinsed off with water and then dried or removed thermally by heating.

The resulting mixture of what in the first case Water and extractant is in turn thermally separates, so that both the cleaning water and the Ex traction agents can be returned to the process.

Instead of the carousel extractor you can of course Lich also other continuously working extractor construction types, such as screw extractors or Band extractors are used.

Following the extraction step, ei ne Interim storage of the pure plastic components respectively.

In a further processing step, the sor ten pure, cleaned thermoplastics extruded and finally granulated, so that homogenized and processed ready raw materials.

As indicated in Fig. 1, the granules obtained after the extrusion are collected in granule silos and then brought into the respective sales or transport units.

After the preparation there is a high quality Recyclate, which is due to its substance properties were practically not covered by a corresponding new product separates. The recyclate can thus be used without any restrictions cations in the product cycle.

It is the first time using the method according to the invention possible, practically any thermoplastic plastic mix from household, industrial and commercial waste prepare, separate and sort by another, high supply valuable use.

Claims (14)

1. Recycling process for the treatment of waste containing plastic mixtures and plastic composite materials, with the steps:

• - mechanical separation of the plastic mixtures and composite materials into unmixed plastics and other residues,
• - Wet processing of single-variety plastics or plastic mixtures for surface cleaning; and
• - Extraction of soluble components of the art materials using an extraction agent.

2. Recycling process according to claim i, characterized net that the plastic mixtures plastics from the group pe PP, PET, PVC, PS, LDPE, HDPE and PUR and the composite materials metals and / or thermally usable rest fabrics and one or more of the aforementioned art substances included. 3. Recycling process according to claim 2, characterized net that the composite materials before wet processing into the plastic components, residues and given if metallic components are separated. 4. Recycling process according to one of the preceding claims che, characterized in that the varietal art fabrics are dried after wet processing. 5. Recycling process according to one of the preceding claims che, characterized in that the plastics or  Shredded plastic mixtures before wet processing will. 6. Recycling process according to one of the preceding claims che, characterized in that the wet treatment with Water and extraction with a CFC and aromatic free Extractant takes place. 7. Recycling process according to claim 6, characterized net that used as the extractant ethyl acetate becomes. 8. Recycling process according to claim 7, characterized net that the extraction with adhering to the plastic by water or by heating the plastic is separated. 9. Recycling process according to one of the preceding claims che, characterized in that the plastics according to the Extraction step can be extruded and granulated. 10. Recycling process according to one of the preceding claims che, characterized in that the composite materials Packaging, electronic waste, aluminum composite materials or cable remnants and the plastic mixtures hollow body, Contain foils and other plastic components. 11. Recycling process according to one of the preceding claims che, characterized in that the mechanical separation ultrasound separation, a Contains screening and / or a screening step.   12. Recycling process according to one of the preceding claims che, characterized in that the wet processing at a temperature of 60 to 95 ° C, preferably 90 ° C is carried out. 13. Recycling process according to one of the preceding claims che, characterized in that one contained in the waste The resulting single-fraction plastic fraction is crushed and without Wet processing is fed to the extraction. 14. Recycling process according to one of the preceding claims che, characterized in that one contained in the waste ne organic fraction during mechanical separation is separated.