WO1997027984A1 - Method and device for extruding waste material into pellets - Google Patents

Abstract

The invention concerns a method and device for extruding material or mixtures of materials, in particular waste. The method proposed is characterized by the following steps: the materials are fed into an extrusion press; in the extrusion press, the materials are fed towards an aperture unit and compressed; just before reacting the aperture unit, the materials are blended by a cutter and/or breaker unit moving at right angles to the direction of flow of the materials, thus leading to further compression of the materials and the materials are extruded through the aperture unit. The device proposed is characterized by the following items of equipment located one after the other in sequence: at least one worm-type compression; a cutter and/or breaker unit which moves essentially at right angles to the longitudinal axis of the compression unit and an aperture unit.

Description

Method and device for processing residues into extrudate pellets

Description

The invention relates to a method for processing substances and in particular residues or waste, which e.g. May contain plastic as well as a device for carrying out the method and a use of the device for reducing the volume of substances and in particular residues, waste or garbage and for increasing the calorific value of the residues.

Nowadays, more and more rubbish is being produced. This inevitably gives rise to the problem of disposing of the garbage or primarily recycling it. There are various approaches for the disposal of waste. For example, waste is recycled thermally. The garbage is burned and the thermal energy is used. A a further possibility is to reduce the volume of the waste and to store it in conventional waste disposal sites. It is particularly desirable to chemically bind or render inert substances that are relevant to the environment. Another possibility is to manufacture materials that can be used as raw materials for new consumer articles. The previously known methods and devices for the treatment of waste have some disadvantages, which are explained below, for example.

A process for the production of extruded or injection-molded articles based on waste containing plastics is known from DE 38 36 953. This known method comprises the following steps:

- mechanical pretreatment,

drying in the case of an approximately 8% excess of the water content in the starting material,

- preheating to 80 to 160 ° C, and

- Pressing or extrusion or injection molding taking place at a temperature between 120 and 250 ° C.

This known method is used for the production of injection molded and extruded parts made of plastics.

By heating to relatively high temperatures, the entire material in a subsequent sequent ^¬ kneading melts a continuous mix ensu ^¬ stet, so that a paste results which is under USAGE ^¬ dung a screw extruder pressed. The paste is heated further with the help of a double jacket to maintain the temperature. The method known from DE 38 36 953 is very complex and requires several different devices for producing the desired parts from plastic. In addition, the method specified in this document has the disadvantage that the compression of the manufactured parts is not optimized. In addition, the device is kept at a relatively high temperature. No further compression or blending takes place during extrusion.

It is known in plastics technology to produce Profi 1 materi al from plastic molding compositions by extrusion. Thermoplastic molding compounds that contain polyolefins, styrene polymer seeds, polyvinyl chloride and others. are used on screw extruders or extruders e.g. processed into sheets, strips, foils, tubes and hoses. The molding compounds are drawn from the storage container into the heated cylinder by the rotating screw of the extrusion press, conveyed, melted and pressed out into the open by a professional nozzle or tool, where the extrudate from further systems, e.g. Calibration, blowing, cooling, stretching, smoothing, peeling and winding systems are taken over.

In the processes known in plastics technology, chemical crosslinking agents and auxiliaries are usually added to the plastics, as described, for example, in DE 37 39 007 A1 or in DE 31 33 897 C2, and the resulting mixture is brought to the crosslinking temperature in the extrusion press Supply heated to increased temperature. The known methods are therefore relatively expensive and complex to carry out due to the additional supply of required material and further heating. The object of the present invention is to provide a process for the preparation of substances and in particular residual substances which causes relatively little cost and which can be used to produce prepared substances and in particular residual substances which, in comparison to the substances produced by the known methods, have a have higher compression, a lower volume and a higher thermal usability. It is also an object of the present invention to provide a device with which the production of processed residues which have the advantages just mentioned is possible.

The present object is achieved by the features of patent claim 1. Further developments of the invention are the subject of subclaims 2 to 20. A solution according to the invention of the task of specifying a corresponding device is given in the features of claim 21. Claims 22 to 36 have features that develop the subject matter of claim 21 according to the invention. Claim 37 specifies an inventive use of the device.

According to the invention, a method for the preparation of substances or substance mixtures and in particular of residual substances or waste is specified according to claim 1, which has the following method steps:

- the fabrics are fed into an extrusion press,

- in the extrusion press, the materials are fed and compressed in the direction of an opening system,

- In an area shortly before the opening system, the substances are mixed by a cutting and / or tearing system moving transversely to the direction of movement, as a result of which the substances are further compressed, and - The fabrics are pressed through the opening system.

The substances can advantageously contain organic materials, binders, such as plastics, etc. The substances preferably contain bindable constituents.

In particular, the following groups of substances are particularly suitable for the process according to the invention: plastic-containing residues, mixed plastics, sorted plastics, residues from waste paper processing, screenings from wastewater treatment, thickened sewage sludge, compost, food residues, grains, chemicals, old labels and leather residues . This list is by no means complete, rather other substances are also suitable for the process according to the invention. It is advantageous if at least some of the ingredients melt at relatively low temperatures. If the substances only melt at higher temperatures, higher temperatures should preferably be used for the process according to the invention.

Due to the pressure achieved and the friction of the cutting and / or tearing system with the substances, the method according to the invention achieves a temperature sufficient in the region in front of the opening system, at least when a binding agent, such as, for example, contained in the substances Plastic is included to melt it.

According to the invention, the essential compaction process takes place through the interaction of a feed system in the extrusion press, a material that is transverse to the direction of movement of the material guided in the feed system moving cutting and / or tearing system (in the following cutting system) and an opening system instead.

The feed system compresses the guided material on the way to the opening system. This material is already heated by friction. Further heating takes place through the transverse movement of the cutting and / or tearing system. Due to the transverse movement of this system, the material is further mixed and compacted. The heating and in particular the compression depends on the opening cross section of the opening system. The heating also depends on the speed of the cutting system and its sharpness. The faster the cutting system cuts through the material, the more the material is heated.

In this case, a temperature is generated which is sufficient to use at least one of the meltable and bindable material portions, which may be contained in the substances, as a binder. The mixing in the area of the cutting system then results in a uniform distribution of the bindable materials within the starting material.

As a result of the cooling of the material pressed through the opening system, the bindable parts of the substance solidify, if such parts of the substance are contained, and together with the other constituents form a compact and reduced-volume product. In addition to this, significant dehumidification of the starting material is possible if the moisture removal system according to the invention is used. In contrast to conventional processes, no addition of crosslinking agents or lubricants is required. moreover it is not necessary to add a defined amount of liquid. It is not even necessary for the substances to contain any bindable components at all.

If the processed materials are to be recycled, there is a strong improvement in thermal recycling, a significantly improved storage and supply option and a reduction in transport costs to approximately 30% compared to those of the non-processed materials.

The temperature of the substances in the region of the cutting system is preferably regulated. With this regulation it is possible to change the properties of the processed substances in a defined manner and in particular to adapt the parameters of the process to the composition of the substances supplied. The temperature is advantageously regulated via the speed of the cutting system. The temperature control can also be carried out using cooling systems, e.g. Water or nitrogen and / or e.g. electrical resistance heating or inductive.

The cutting system preferably rotates. Through this

The measure provides a compact possibility of implementation that enables simple control of the system.

Plastics that melt in the range of 70 to 120 ° C are usually found in residues or waste. For such residues, it is advantageous to reach temperatures in this range in the extrusion press. At high temperatures, gases can be generated that are toxic, for example. It could also cause fire come. In this respect, it is ensured that only such temperatures arise during the processing of the substances described, in particular residues or waste.

The materials are preferably comminuted before being fed to the extrusion press. This measure enables homogeneous mixing. Mixing the supplied substances enables an even bond of the processed substances.

To protect the means for cutting, tearing, pressing, mixing and blending used in the extrusion press, a magnetic separator and / or a magnetic magnet separator is preferably provided, which separates the magnetic or non-ferrous metals.

A controllable mixing arm is preferably provided, which generates a uniform and homogeneous material flow from residual materials to the extrusion press. The more uniform the material flow to the extrusion press, the more uniform is the density of the processed material. In addition, the processed material is networked as evenly as possible.

In contrast to conventional methods, no liquid and in particular no binding agent are added to the residual materials in order to obtain corresponding end products by extrusion. It is preferable to dispense excess liquid from the extrusion press.

In order to optimize the method according to the invention, gas flow detection and analysis of the gas produced in the extrusion press can advantageously be carried out become. This measure allows parameters such as supplied substances, rotational speed of the cutting system, rotational speed of the feed means or compression by the feed means, optimal cross section of the openings of the opening system etc. to be optimized. In particular, it is advantageously possible to separate processed substances, which contain an excessively high concentration of environmentally relevant pollutants, from the processed material, in order, if necessary, to send them to a separate treatment.

Behind the opening system, the processed material is preferably portioned into a desired size by cutting with the aid of a cutting device. The resulting strand pellets can be cut to the desired length.

If the substances have too high a moisture content, a pre-dewatering preferably takes place before the substances are fed to the extrusion press. The pre-dewatering step can take place before pre-comminution or afterwards and advantageously takes place after any metallic parts have been removed.

For some substances it is advantageous if a pre-compression takes place when the extrusion press is fed. The measure enables an increased compression effect to be achieved. For this purpose, the substances are preferably at least partially fed vertically to the extrusion press and / or at least part of the pre-compression takes place due to the force of gravity. The device according to the invention for carrying out the method has the following means arranged one behind the other:

- at least one screw compression system, e.g. has one or more working screws,

- A cutting system that is movable substantially transversely to the longitudinal axis of the worm, and

- an opening system.

The actual compaction and / or binding process results from the interaction of the screw compression system or the working screw, the subsequent cutting or tearing system and the following opening system.

The screw compression system advantageously has a decreasing pitch of the screw thread in the direction of the opening system. As a result, compression increases in the direction of the opening system. The screw compacting system preferably has sharp edges, as a result of which the materials fed to the screw compacting system can advantageously be comminuted even further.

A feed system is preferably provided that feeds the residues to the working screw. This feed system is advantageously a screw conveyor or a conveyor arm, which preferably conveys the materials transversely to the longitudinal axis of the screw compression system. The funding ensures a continuous flow of material to the screw compression system. The arrangement transversely to the longitudinal axis of the worm kenverdi chtungssystems enables a compact Bauwei ^¬ se. The compression is thus preferably optimized that the conveyor system pre-compresses the substances. For this purpose, the conveyor system is arranged above the screw compression system, whereby the gravitation is used for pre-compression and / or the conveyor system is a screw, the screw flight of which has a smaller and smaller pitch in the direction of the screw compression system.

The cutting and / or tearing system is advantageously a rotating set of cutting edges or blades. A set of cutting edges also means, for example, only one cutting edge or. Sound .

By using a set of blades, the material fed into the area of the opening system is further crushed and at the same time heated and further compressed. If the variable parameters are set correctly, this results in a paste-like liquid or a paste-like state of the material that is reminiscent of a Newtonian liquid.

The set of cutting edges is advantageously arranged rotationally symmetrically similar to the cutting edges in a meat grinder. By varying the speed of rotation, it is possible to set both the temperature and the pressure in the vicinity of the opening system. The blades, which can have different pitches, are preferably interchangeable.

The opening system can contain any type of opening. However, a perforated disc is used, the holes of which differ in size depending on the application. A controllable mixing arm known per se is preferably provided for producing a uniform and homogeneous material flow to the conveying means.

The preferred provision of a magnetic separator and / or a magnetic separator before feeding the material to the screw compression system for sorting out metal extends the life of the means used.

The material emerging from the opening system, which is also referred to as strand pellet, is preferably cut with a means, which in particular can be a knife.

A moisture removal system is advantageously provided, with which an excess of moisture in the residues can be removed.

A pre-cutter is preferably provided between the screw compression system and the cutting and / or tearing system. This serves for further pre-comminution, and is preferably a disk with openings on which the supplied material can be cut or torn off through one end of the screw compacting system.

The device according to the invention is advantageously used to reduce the volume of substances and in particular residues or waste to less than half of the previous volume. This advantageously also significantly increases the calorific value of the residual material.

In the following, the invention is described without limitation of the general inventive concept Execution examples explained. No further explanatory drawing is referred to here.

In one exemplary embodiment, the method according to the invention first provides for the comminution of the delivered residues. Subsequently or alternatively before comminution, any metallic material is removed from the residues with the aid of a magnetic separator and / or a magnetic separator.

The material is then mixed. The mixed material is fed evenly and homogeneously to a screw conveyor using an adjustable mixing arm. A homogeneous compaction of the material is achieved in the extrusion press through the homogeneous material flow.

The material conveyed by the screw conveyor is fed to a working screw in an extrusion press. The work screw can be designed in such a way that further mixing and comminution of the supplied material takes place. The closer the material is conveyed in the direction of the opening system, the greater the compression if a work screw or a screw compression system is used whose pitch of the screw thread is reduced. The material heats up due to friction. The opening system can be a perforated disc.

Shortly before the perforated disc, the material flow is further mixed, heated and compressed by rotating blades. There are considerable increases in temperature which can be regulated by the speed of rotation of the cutting edges. By heating the material, the bindable melt Materi al antei 1 e, whose melting point is below the temperature reached. The further mixing of the material, which contains, for example, melted plastic, enables a homogeneous distribution of the melted plastic, so that when the mixture is subsequently cooled to a temperature below that of the melting point, the plastic is uniformly crosslinked. In particular, this also enables the further contents of the processed material to be enclosed.

The material is then pressed out through the perforated disc and cut to the desired length by a cutter, which can in particular be a knife. The compression and also the temperature (different friction) are set by means of different opening cross sections. Pressing the material out of the extrusion press through the perforated disk increases the temperature of the material due to the friction.

For example, unnecessary liquid is drained from an area before the area of maximum compression. For this purpose, the device could be designed in such a way that an incline is provided in the area of the working screw, which allows the liquid to run off against the conveying direction of the material.

Depending on which ingredients are contained in the residues or in the garbage, a more or less high temperature in the extrusion press in the area just before the perforated disc is necessary in order to achieve optimal compression and optimal properties of the extruded pellets. This results on the one hand from the melting points of the bindable materials contained in the residues, such as plastics and be attached on the other hand from a possibly required Tempe ^¬ temperature, toxic substances in the example. For example, polyethylene melts at 70 ° C, while other plastics only melt at much higher temperatures. From this consideration, the temperatures required for the person skilled in the art can be easily measured in the area just before the perforated disk.

A temperature of approx. 100 ^* C has proven to be advantageous for processing the usual plastic-containing residues.

The temperature can not only be controlled by regulating the speed of rotation of the cutting edges. Rather, it is also possible to control the temperature via, for example, inductive heating, resistance heating or cooling, which at least partly. are arranged above the extrusion press. For cooling, for example, hoses or pipes come into question, which are arranged around or in the device and through which water or even liquid nitrogen flows.

Environmentally relevant substances in the residues or the garbage are problematic. In order to recognize these and remove them from the end product, it is advisable to carry out an analysis. This analysis can be carried out directly on the end product, for example by chemical analysis. However, the analysis is advantageously carried out on the gases generated in the extrusion presses. The gases produced are passed directly past a sensor, for example from the extrusion press, or the gas is dissolved in water and the pH is determined, for example. The latter alternative is particularly useful if Plastics are contained in the residues that contain chlorine compounds.

The encapsulated pellets produced are rendered inert by the possible encapsulation of the residues according to the invention which are not melted in the extrusion press. These strand pellets can be used, for example, as thermal insulation material or as a construction additive. The strand pellets usually have a calorific value of 300000 kJ and a volume reduced by 2/3.

The method presented is not restricted to substances or mixtures of substances which contain bindable constituents, rather, far more substances or mixtures of substances can be determined with the method pel 1 according to the invention.

Claims

claims 1. Process for the preparation of substances or mixtures of substances, in particular residues or waste, with the following process steps: - the fabrics are fed into an extrusion press, - in the extrusion press, the materials are fed and compressed in the direction of an opening system, - In an area shortly before the opening system, the materials are mixed by a cutting and / or tearing system moving transversely to the direction of movement, and - The fabrics are pressed through the opening system. 2. The method according to claim 1, characterized in that the substances bi-compatible Components included. 3. The method according to claim 1 or / and 2, characterized in that a regulation of the temperature of the residues is carried out in the area in front of the opening system. 4. The method according to claim 3, characterized in that the regulation of the temperature via the speed of the cutting and / or tearing system happens. 5. The method according to claim 4, characterized in that the cutting and / or tearing system rot i ert. 6. The method according to one or more of claims 3 to 5, characterized in that the temperature is controlled by a cooling system and / or a heating system. 7. The method according to claim 6, characterized in that the cooling by water or nitrogen flows through lines and the heating by an electrical resistance heater or inductively. 8. The method according to one or more of claims 1 to 7, characterized in that a temperature between 70 and 120 ° C is reached in the area in front of the opening system. 9. The method according to one or more of claims 1 to 8, characterized in that the materials are crushed before being fed to the extruder. 10. The method according to one or more of claims 1 to 9, characterized in that magnetic and in particular iron-containing substances are separated from the substances to be fed to the extruder with the aid of a magnet separator. 11. The method according to one or more of claims 1 to 9, characterized in that with the aid of a non-ferrous magnetic separator, non-ferrous metals are separated from the materials to be supplied to the extrusion press. 12. The method according to one or more of claims 1 to 11, characterized in that the substances are mixed before being fed to the extrusion press. 13. The method according to claim 12, characterized in that a controllable mixing arm generates a uniform and homogeneous stream of substances to the extrusion press. 14. The method according to one or more of claims 1 to 13, characterized in that superfluous liquid is separated from the extrusion press. 15. The method according to one or more of claims 1 to 14, characterized in that gas flow detection and analysis of the gas produced in the extrusion press is carried out. 16. The method according to claim 15, characterized in that the processed substances which have an excessively high concentration of environmentally relevant pollutants are separated out by the analysis. 17. The method according to one or more of claims 1 to 16, characterized in that behind the opening system, the processed material is portioned into a desired size by cutting with the aid of a cutting device. 18. The method according to one or more of claims 1 to 17, characterized in that a pre-dewatering takes place before feeding the substances to the extrusion press. 19. The method according to one or more of claims 1 to 18, characterized in that a pre-compression takes place when the substances are fed to the extrusion press. 20. The method according to claim 19, characterized in that the substances are at least partially fed vertically to the extrusion press and / or at least part of the pre-compression takes place by gravity. 21. Device for carrying out the method according to one or more of claims 1 to 20, with the following means arranged one behind the other: - at least one screw compression system, a cutting and / or tearing system which can be moved essentially transversely to the longitudinal axis of the screw compression system, and - an opening system. 22. The apparatus according to claim 21, characterized in that the screw compression system in the direction of the opening system has a decreasing pitch of the screw thread. 23. The apparatus according to claim 21 or / and 22, characterized in that the screw compression system has sharp edges. 24. The device according to one or more of claims 21 to 22, characterized in that a conveyor system is provided that the substances feeds the screw compression system. 25. The device according to claim 24, characterized in that the conveyor system is a screw conveyor. 26. The apparatus according to claim 24 and / or 25, characterized in that the conveyor system conveys the residues substantially transversely to the longitudinal axis of the screw compression system. 27. The device according to one or more of claims 24 to 26, characterized in that the conveyor system pre-compresses the substances. 28. The device according to one or more of claims 21 to 27, characterized in that the cutting and / or tearing system is a rotating set of cutting edges or blades. 29. The device according to claim 28, characterized in that the blades are interchangeable and / or can be used with different slopes s i nd. 30. The device according to one or more of claims 21 to 29, characterized in that the opening system is a perforated disk. 31. The device according to one or more of claims 21 to 30, characterized in that an adjustable mixing arm is provided for generating a uniform and homogeneous material flow to the conveyor system. 32. Device according to one or more of claims 21 to 31, characterized in that a magnetic separator and / or a Ni chtei senmagnetabscheider is provided, which removes or the metallic materials from the substances before feeding to the screw compression system. 33. Device according to one or more of claims 21 to 32, characterized in that a means is provided for cutting off the resulting strand pellets. 34. Device according to one or more of claims 21 to 33, characterized in that a moisture removal system is provided with which an excess of moisture is removed in the residues. 35. Device according to one or more of claims 21 to 34, characterized in that a pre-cutter is provided between the screw compression system and the cutting and / or tearing system. 36. Apparatus according to claim 35, characterized in that the pre-cutter is a disc with openings on which the supplied material can be cut off or torn off by one end of the screw compression system. 37. Use of the device according to one of claims 21 to 36 for reducing the volume of substances, in particular residues or waste, to less than half of the previous volume. 38. strand pellet which has been produced by the method according to one or more of claims 1 to 20.