Method and apparatus for the processing of used Styrofoam® material

Abstract

Method for processing used expandable polystyrene material with adhering substances comprising the following process steps: - Deformation of the elastic particles of expandable polystyrene in a decontamination plant (1) without cutting comminution such that the adhering substances of adhesives and / or plasters and / or PU foams and / or solid paints flake off, while preserving the pearly and cellular structure of the expandable polystyrene; - Separation of the mixture of substances consisting of adhering substances and particles of expandable polystyrene by density separation in a separation device (2).

Description

The invention relates to a method and a device for processing used Styropor® material and is applicable for returning so-called Styropor® cuttings to the pearly and cellular state. Styropor® is, according to the nomenclature, a name used by BASF AG for expandable polystyrene (EPS). Used Styrofoam® has the disadvantage of being contaminated with substances such as adhesives, plaster, and other impurities. The recycling of used Styrofoam® requires that its granular and cellular structure be preserved. Styrofoam®, in its granular and cellular form, is very elastic and very lightweight, with a density of approximately 30 kg / m³. In comparison, mineral contaminants such as adhesives and plaster have a density of 1700 to 2000 kg / m³. Due to their structure, these mineral components are not as elastic. The present invention addresses this issue with a physical principle for separating elastic substances from less elastic ones. No method or system is known from the current state of the art that can fulfill this task. DE 101 05 995 A1 describes a collection method and a collection device for collecting foam gas from expanded thermal insulation material contained in waste material, such as cooling devices, etc. The waste material is shredded in shredding machines. The shredded parts contain shredded expanded thermal insulation materials, plastic pieces, metal pieces, etc. The shredded parts are separated by means of a wind turbine separator. A method for the regenerative granulation of EPS cold-pressed materials is known from CN 1 11 438 837 A, which includes the processing steps of crushing and conveying the waste EPS cold-pressed materials. DE 197 14 793 C1 discloses a device and a method for the wet mechanical separation of a solid mixture, in particular of plastics of different densities. German patent DE 20 2016 106 083 U1 discloses a plant for processing EPS (Styrofoam®) waste contaminated with HBCDD (hexabromocyclododecane), comprising: - at least one comminution device for comminuting the waste, in particular a cross-flow shredder, wherein the waste to be processed can be fed to the comminution device, the comminution device has at least one discharge opening through which the comminutioned waste can be discharged, - at least one first extraction system connected to the discharge opening for extracting the comminutioned waste and the process gas released during comminution, - at least one cyclone connected to the first extraction system for separating a heavy fraction and a light fraction of the comminutioned waste, - at least one final extraction system connected to a cyclone for the process gas released during comminution.- with at least one exhaust gas treatment system for cleaning the process gas of hexabromocyclododecane (HBCDD) and / or biocides and / or fungicides. The invention is therefore based on the objective of creating a method and a device with which used Styrofoam® can be easily and inexpensively processed and returned to the economic cycle. This problem is solved by a method having the features of claim 1 and by a device having the features of claim 7. Advantageous embodiments of the invention are contained in the dependent claims. A particular advantage of the invention lies in the environmentally friendly mechanical processing of the used Styropor® material by implementing the following process steps: - Deformation of the elastic particles of expandable polystyrene in a decontamination plant without cutting comminution, such that the adhesions of adhesives and / or plasters and / or PU foams and / or solid paints flake off, while the pearly and cellular structure of the expandable polystyrene is preserved; - Separation of the mixture of substances consisting of adhesions and particles of expandable polystyrene by density separation in a separation device. An additional advantage of the invention results from the fact that the deformation of the elastic Styropor® particles is achieved by compression and / or pressing of the Styropor® particles, by flinging the Styropor® particles against the geometry of a stator by means of a rotor and the density separation is carried out by centrifugal force generated by means of a rotating centrifugal disc. It is also advantageous that the Styrofoam® particles freed from the adhesions are vacuumed up above the spinning disc and the adhesions sink towards below the spinning disc. A significant advantage of the invention is the robust and effective design of the inventive device for processing the used Styropor® material, which is characterized in that a decontamination system is connected to a separation device, wherein the decontamination system has a rotor and a stator with a geometry and the separation device comprises a centrifugal disc arranged in a housing, above which a feed for the Styropor® material with adhesions and a discharge for the Styropor® material freed from the adhesions are arranged and openings are arranged between the inner wall of the housing and the centrifugal disc through which the adhesions sink. It is advantageous to arrange an inlet for atmospheric supply air below the centrifugal disc. The rotor has rotor discs on which flails are arranged, and the geometry has arc-shaped depressions with inwardly directed inclined planes. The invention will be explained in more detail below with reference to exemplary embodiments illustrated at least partially in the figures. The figures show: Fig. 1 a flow diagram illustrating the processing sequence, Fig. 2 a detailed view of the decontamination system according to the invention, Fig. 2a rotor array in V-shape, Fig. 2b rotor array in VV-shape, Fig. 3 a detailed view of the separation device according to the invention. As shown in Fig. 1, the basic principle of processing used Styrofoam® is a multi-stage rotary process. This generates the different speeds necessary for shredding and decontamination. The process is explained below for each individual position. Styrofoam® in the form of so-called offcuts is stored at the manufacturer's plant and processed promptly. Position 1: A conveyor system 20 takes over the product, which in the present embodiment is fed in manually by an employee. Below the conveyor system 20 a drainage system 21 and a lower conveyor protection system 22 are arranged. Position 2: The material enters a primary crusher 24 via a metal detection bridge 23. Position 3: In the pre-crusher 24, the material is pre-shredded. The adhesives and plasters adhering to the Styrofoam®, being mineral components, lead to wear of the components of the pre-crusher 24. Position 4: Decontamination facility: The decontamination system 1 according to the invention, along with the separation system 2, is the core component of the device. Here, the elastic, pearly Styrofoam® particles are separated from the mineral deposits. The cell structure also loses these deposits in the process. The separation occurs physically and without the addition of water. Within the scope of the invention, it was important to find out which geometry, which must not be cutting, would achieve the best possible result with minimal wear. The decontamination system 1 according to the invention comprises a rotor 3 and a stator 4 with a housing, the rotor 3 being equipped with a drive. A material feed is located tangentially. The material is fed to the rotor 3 by gravity. The rotor 3 then sets the Styrofoam® in motion such that centrifugal acceleration begins first, and then the Styrofoam® is thrown by tangential acceleration against the inwardly directed geometry 5 anchored to the stator 4, causing the Styrofoam® to deform so that all adhering materials are flaked off by the impact and cannot withstand the deformation. This is because Styrofoam® is a very elastic material that is easily deformable. The adhering materials consist of mineral substances (plasters and adhesives), as well as PU foams and other less elastic substances such as plastic plasters, solid paints, and other materials. These components do not move with the material and detach due to the enormous deformation of the Styrofoam®. This is an induced physical process that separates elastic from non-elastic materials at normal temperature through material stresses. The highly elastic Styrofoam® retains its pearly, cellular structure and does not change its original shape during this process. Instead, this decontamination process cleans it, allowing it to be reused as a raw material in production. After the materials leave decontamination unit 1, they are still a mixture of Styrofoam, plaster, adhesives, etc., so a subsequent step is initiated. This involves separation unit 2, which cleanly separates the Styrofoam from the plaster, adhesives, and other materials. The movement sequences of the Styropors® in the decontamination plant 1 will be described in detail below. In Fig. 2, the geometry 5 for non-cutting comminution is shown in detail. From the primary crusher 24 in position 3 according to Fig. 1, the pre-shredded Styrofoam® pieces, with an edge length of 0 to 50 mm, are fed by a feeder 25 into the tangentially arranged inlet chute of the decontamination system 1. In the present embodiment, the housing of the decontamination system 1 is a robust welded construction, preferably made of 15 mm sheet metal. The interior is lined with a 10 mm thick, wear-resistant steel. The rotor 3 has external bearings and drive components. As the rotor 3 rotates, the Styrofoam® is initially subjected to centrifugal acceleration at a peripheral speed of 502 m / min. This acceleration causes the Styrofoam® to achieve the desired geometry 5 with arcuate depressions 17 and inwardly inclined planes 15.The centrifugal acceleration, combined with the subsequent tangential acceleration, causes the Styrofoam® to be flung so violently—and repeatedly—against the inward-facing planes 15 that a recurring deformation, compression, and compression of the Styrofoam® occurs. This change in shape separates the elastic components (Styrofoam®) from the non-elastic components (mineral components and other materials). These components simply break off because adhesion is no longer possible due to differing deformation forces and stresses. This process not only cleans the surface of the Styrofoam® granules but also the open cells of the cut surfaces, which are sometimes visible. This demonstrates the excellent properties and inherent strength of Styrofoam®, as well as its high resistance to deterioration. After the Styropor® particles, which have a closed surface, strike the rotor, they are guided back to rotor 3 via centripetal acceleration and fed back into the uniformly rotating reference system. This process is aided by flails 13 (hammers) that have no cutting effect. This rotation system maintains the pearly and cellular structure of the Styropor® and ensures the quality of its use as cleanly manufactured Styropor®. The flails 13 (hammers) are arranged on rotor disks 3a, 3b to 3n, as shown in Figures 2a and 2b. These flails have their own axes, which can deflect under high load and intentionally change the gap between the flail (hammer) and the geometry 5. Simultaneously, however, the centrifugal force pulls them back into the radial position because the center of gravity is asymmetrically arranged. The rotor disks 3a, 3b to 3n are mounted on a square drive shaft, and each rotor disk 3a, 3b to 3n also has its own axes for receiving the flails 13 (hammers). Various flail configurations are possible on the rotor disks 3a, 3b to 3n. In the present embodiment, these configurations range from a minimum of three flails 13 to a maximum of twelve flails 13 (hammers). Since not all mineral and plastic compounds, such as adhesives, plasters, and paints, have the same properties, rotor 3 is designed to allow for considerable flexibility in rotor configuration and composition. This is illustrated in the diagram, first with a single "V" configuration (Fig. 2a) and then with a double "VV" configuration (Fig. 2b). The variety of options therefore offers many possibilities. At this point, however, we still have a mixture of Styrofoam® and the mineral components and other substances, which are still separated together via a sieve basket and are separated and separated in position 5, Fig. 1. In front of position 5, the elastic Styropor® particles and the separated mineral components are in sand form, thus forming a mixture that is essentially unusable. Position 5: Separating device: The separation device 2 has a centrifugal disc 6 arranged in a housing 9. Here, particles are flung away, similar to the process used by gritters spreading de-icing salt in winter road maintenance. The centrifugal disc 6 is used for Styrofoam®, but with the difference that a negative pressure prevents the Styrofoam® from sinking through the openings 11 with the other materials beyond the gap "X" shown in Figures 1 and 2. The Styrofoam®, with its density of approximately 0.03 g / cm³, floats on the centrifugal disc 6, while all other materials are flung outwards by centrifugal force and sink through the openings 11 on the inner wall 10 of the housing 9. These material streams all have a higher density and can be separated from each other by this device due to the resulting centrifugal forces.Simultaneously, atmospheric air flows through an intake duct 16 centrally beneath the centrifugal disc 6 and through the variable gap "x", supporting the Styrofoam®. The Styrofoam® is thus held suspended above the centrifugal disc 6. Simultaneously, a tangentially mounted turbine screw ensures the continuous skimming of Styropor® residues from adhesives and / or plasters and / or PU foams and / or solid paints, while preserving the pearly and cellular structure of the expandable polystyrene. This material is located above the centrifugal disc 6 and is then transported away. Heavier materials sink to the bottom through the openings 11 on the inner wall 10 of the housing 9 and are discharged into a container 28 via a screw conveyor 27. The centrifugal disc 6 is driven by a drive shaft 26. The product can then enter the production process via conveying equipment (position 7), dust removal (position 6), intermediate silo and main silo (position 8). The invention is not limited to the embodiments shown here. Rather, it is possible to realize further embodiments by varying and combining the aforementioned features without departing from the scope of the invention.

Claims

Method for processing used expandable polystyrene material with adhering substances comprising the following process steps: - Deformation of the elastic particles of expandable polystyrene in a decontamination plant (1) without cutting comminution such that the adhering substances of adhesives and / or plasters and / or PU foams and / or solid paints flake off, while preserving the pearly and cellular structure of the expandable polystyrene; - Separation of the mixture of substances consisting of adhering substances and particles of expandable polystyrene by density separation in a separation device (2). Method according to claim 1, characterized in that the process step of deformation is preceded by a mechanical comminution of the expandable polystyrene material. Method according to claim 2, characterized in that the comminution is carried out in the size range of 0 - 50 mm. Method according to claim 1, characterized in that the deformation is achieved by compression and / or pressing of the expandable polystyrene particles by flinging the expandable polystyrene particles against the geometry (5) of a stator (4) by means of a rotor (3). Method according to claim 1, characterized in that the density separation is carried out by means of a centrifugal force generated by means of a rotating centrifugal disc (6). Method according to one of the preceding claims, characterized in that the particles of expandable polystyrene freed from the adhesions are suctioned off above the centrifugal disc (6) and the adhesions sink in the direction below the centrifugal disc (6). Device for processing used expandable polystyrene material, characterized in that a decontamination system (1) is connected to a separation device (2), wherein the decontamination system (1) has a rotor (3) and a stator (4) with a geometry (5) and the separation device (2) comprises a centrifugal disc (6) arranged in a housing (9), above which a feed (7) for the expandable polystyrene material with adhesions and a discharge (8) for the expandable polystyrene material freed from the adhesions is arranged and openings (11) are arranged between the inner wall (10) of the housing (9) and the centrifugal disc (6) through which the adhesions fall. Device according to claim 7, characterized in that a supply (12) for atmospheric supply air is arranged below the centrifugal disc (6). Device according to claim 7, characterized in that the rotor (3) has rotor disks (3a, 3b,...3n) on which flails (13) with hard metal (14) are arranged. Device according to claim 7, characterized in that the geometry (5) has arcuate recesses (17) with inwardly directed inclined planes (15).

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