Method for recycling and processing electroplated plastic workpieces

Abstract

The present invention relates to a method for recycling and regenerating electroplated plastic workpieces (4), in which the workpieces (4) are decoated in a decomposition unit (22) using the effect of submerged discharge to produce a suspension containing plastic granules (32) and coated granules (34), the suspension is dewatered, and the plastic granules (32) are separated from the coated granules (34) by magnetic separation using a magnetic separator (42).

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for the recycling and reprocessing of electroplated plastic workpieces. The present invention further relates to the use of a submerged discharge effect (electrohydrodynamic effect) for the removal of coatings from electroplated plastic workpieces. [Background technology]

[0002] Today, plastic workpieces are used in a wide range of applications due to, for example, their light weight, chemical stability, and easy and low-cost manufacturing using injection molding. Plastics can be coated with metals to improve their optical, electrical, mechanical, or thermal properties.

[0003] Metal coatings on plastics can be achieved by electrolytic deposition, which is also known as plastic electroplating or plating on plastics (POP). Plastics are generally not electrically conductive, so the plastic surface must first be covered with a conductive layer that adheres well to the surface for subsequent electrolytic coating.

[0004] Due to the strong adhesion of the metal layer to the plastic material, the recycling or reprocessing of electroplated plastics is relatively laborious and costly. In particular, relatively high quality and purity are required for secondary plastics, i.e., recycled plastics, to be usable as a replacement for primary plastics. To date, it has not been possible to decoat (downcycle) electroplated products or electroplated plastics by purely mechanical means without impairing the quality of the recycled plastics, and as a result, secondary plastics generally do not meet the quality requirements for plastic reuse. Therefore, an efficient recycling solution is needed to effectively utilize plastic raw materials and return inferior quality materials to production instead of discarding them.

[0005] German Patent Application Publication No. 10237960A1 describes the stepwise etching of electroplated coatings on electroplated plastic parts using hydrochloric acid, hydrogen peroxide, and sulfuric acid. This process consumes large amounts of the chemicals used, hydrogen peroxide and sulfuric acid, and requires subsequent washing and drying of the polymer. Furthermore, the use of acid damages the polymer structure of the plastic, reducing the material value of the recycled product. Known metal removal processes damage the plastic so severely that it cannot be reused for electroplating. Therefore, recycled products from such methods can only be used in lower-quality applications.

[0006] EP 2771120B1 discloses a method and apparatus for selectively decomposing recycled materials into recyclable materials using the in-liquid discharge effect. In this method, an impulse discharge with a discharge energy of 200 to 1500 J per electrode is generated primarily in the liquid between an electrode on the bottom side of a container and multiple electrodes arranged on the lid side of the container. The average electric field strength is less than 5 kV / mm (kilovolts per millimeter), and the repetition frequency of the high-voltage impulse is less than 10 Hz (hertz). Specifically, the method and apparatus are described for use with discarded electrical and electronic equipment, coated metal foils, printed circuit boards, and storage batteries.

[0007] WO 2017 / 037129 A1 describes a method for recycling glass-semiconductor-polymer composites, in which the glass components are separated using a submerged discharge effect, using an impulse discharge with a discharge energy of 200 J to 1500 J per electrode, a high voltage in the range of 30 kV to 50 kV, and a high-voltage pulse repetition frequency of less than 10 Hz.

[0008] WO 2019 / 234109 A1 discloses a method and apparatus for pulverizing and decomposing materials by the effect of submerged discharges. The impact discharges used have a discharge energy of less than 100 J, a high voltage in the range of 30 kV to 50 kV, and a high-voltage pulse repetition frequency in the range of 20 Hz to 100 Hz. The method is used to treat brittle materials or products containing brittle components, particularly silicates, ceramics, silicon, and silicon carbide, as well as materials requiring high purity, particularly glass, ceramics, semiconductor materials, glass-polymer composites, especially photovoltaic modules, laminated safety glass, and / or metallurgical slag. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] German Patent Application Publication No. 10237960A1 [Patent Document 2] European Patent No. 2771120B1 [Patent Document 3] International Publication No. 2017 / 037129A1 Brochure [Patent Document 4] International Publication No. 2019 / 234109A1 Brochure Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention is based on the object of providing a particularly suitable method for the recycling and reprocessing of electroplated plastic workpieces. In particular, the further processing goal is to achieve plastic granules with the highest possible purity and quality. The present invention is also based on the object of providing a particularly suitable apparatus for carrying out this method. [Means for solving the problem]

[0011] This problem is solved according to the invention with respect to the method by the features of claim 1, with respect to the device by the features of claim 7 and with respect to the use by the features of claim 14. Advantageous embodiments and further developments are the subject of the dependent claims. Advantages and embodiments mentioned with respect to the method also apply mutatis mutandis to the device and vice versa, to that effect.

[0012] Where method steps are described below, advantageous embodiments of an apparatus result in particular from the fact that the apparatus is configured to perform one or more of these method steps.

[0013] The method according to the invention is intended for, and is suitable and adapted for, the recycling and reprocessing of workpieces made of electroplated plastics.

[0014] Here and below, recycling is understood to mean, in particular, the decomposition of multi-component workpieces or recycled materials into reusable materials (recyclates).Here and below, electroplated plastics is understood to mean, in particular, the metallization of plastics, i.e., the coating of plastic materials with a metal coating (metallization), where the metal coating is provided on the plastic material in particular by electrolytic deposition (electroplated coating).

[0015] The workpieces are, for example, electroplated products or electroplating waste. The plastic or plastic material of the workpieces is, for example, a thermoplastic, in particular acrylonitrile-butadiene-styrene copolymer (ABS), or polyamide (PA), or ABS and polycarbonate (PC). The electroplated or metal coating is produced, in particular, from copper (Cu), nickel (Ni), and / or chromium (Cr).

[0016] According to this method, the workpiece is mechanically decoated in the decoating process or step by using the effect of a discharge in a liquid in a decomposition unit. Preferably, a shock wave method is used in a liquid, such as water or distilled water, in which strong pressure waves, so-called shock waves, are used to decoat electroplated products or electroplated plastics. In this case, "decoating" or "decoating" is understood to mean, in particular, the separation or detachment of the plastic material from the metal coating. This means that, according to the present invention, a shock wave method is used to decoat electroplated plastics.

[0017] The workpieces may be formed as whole parts or as (pre-)comminuted parts (plastic fragments). Preferably, prior to the shock wave treatment in the decomposition unit, the workpieces are first crushed into workpiece granules (powder material) by a crushing device in a preceding pre-comminuted step. This ensures homogenization of the workpiece material for the subsequent recycling process. For example, the workpieces are crushed into workpiece granules with an average particle size of less than 50 mm, in particular less than 20 mm. This mechanical pre-treatment or crushing step can already cause partial removal of the plastic and electroplated coating. Furthermore, pre-comminuted processing increases the efficiency of the decomposition unit or shock wave treatment.

[0018] The decomposition unit produces a suspension of liquid and plastic granules, as well as coated granules, as materials. In other words, the workpieces or workpiece granules are decomposed into plastic granules and coated granules by the decomposition unit. Here and below, plastic granules are understood to mean, in particular, the plastic fraction or the plastic product containing granules and debris. Correspondingly, here and below, coated granules are understood to mean, in particular, the coating fraction or the coated product containing granules and debris. In this case, the coated granules consist of magnetic granule fragments of peeled coating and weakly magnetic granule fragments of plastic debris containing coating residues.

[0019] For example, shock wave treatment can be followed by sieving to separate out metal-rich fines, and optionally a washing step can be added to clean / wash off the plastic surface.

[0020] The raw material or suspension from the decomposition unit is then (pre-) dewatered and, for example, dried. This removes the liquid from the suspension, leaving essentially only a heterogeneous mixture of plastic granules and coated granules. Pre-dewatering and, if necessary, drying the milled workpiece product facilitates sorting of the mixed material. Preferably, the mixture of plastic granules and coated granules contains less than 10% by weight, in particular less than 5% by weight, of residual moisture after dewatering and, if necessary, drying.

[0021] Finally, a magnetic separator is used to sort or separate the plastic granules from the coated granules by magnetic separation. In other words, sorting of the plastic granules and the coated granules is performed. The peeled coating components that were not separated by the preliminary screening are separated from the plastic by single-stage or multi-stage magnetic separation. In addition, by using magnetic separation, plastic fragments with the coating remaining can be efficiently sorted. This makes the method particularly suitable.

[0022] The result is a pure (non-magnetic) plastic product or plastic granules with a purity of more than 99% by weight, for example more than 99.9% by weight, a ferromagnetic product (peeled coating), and a weakly magnetic product (plastic debris with coating residues). The plastic product or plastic granules are filled, for example, at a filling station, in particular by big-bag filling.

[0023] The weakly magnetic product (plastic debris containing coating residues) can be returned to the decomposition unit for a shock wave based coating removal process.

[0024] Preferably, the plastic granules or recycled plastics have a sufficiently high quality or purity for direct recycling or direct reintroduction into the production, thereby allowing for the substitution or saving of new or primary plastics. The plastic granules have a purity of, for example, more than 99% by weight, in particular more than 99.9% by weight. This means that secondary plastics recycled using the method according to the invention are essentially free of downcycling and qualitatively equivalent to primary plastics.

[0025] The removal of coatings from workpieces according to the invention using the submerged discharge effect or shock wave method provides a particularly simple and cost-effective method that uses only electric current and mechanical pressure waves, so that no chemical and / or thermal methods are required to remove the coating.

[0026] The shock wave process subjects the plastic to minimal mechanical stress, thereby keeping the size of the fragments or particles nearly constant. During the coating removal process, the proportion of fine fractions produced is particularly small. For example, the proportion of fine fractions with a particle size of less than 1 mm is less than 10% by weight, particularly less than 5% by weight, and preferably less than 2% by weight. Therefore, the method according to the present invention ensures a narrow particle size distribution of the plastic granules, which is advantageous as input for industrial processes.

[0027] Furthermore, this method allows for the recovery of usable metal fractions or usable metal concentrates from the (electroplated / metal) coating of the workpiece, since the coating is not decomposed during the process. In particular, the remaining composite material (plastic debris containing coating residues) is weakly magnetic and can therefore be easily sorted back, allowing for a simple sorting method using a magnetic separator.

[0028] In a further possible embodiment, the suspension liquid is returned to the decomposition unit during the dewatering process. This reduces the liquid consumption of the decomposition unit. The resulting recirculation of the (process) liquid (process water) continues until a limiting conductivity is reached. In other words, the suspension liquid is tested for electrical conductivity and compared with a stored threshold or limit value. If the limiting value is not reached or is below the limiting value, the liquid is returned to the decomposition unit. If the limiting value is reached or exceeded, the liquid is discarded and new liquid is fed to the decomposition unit. The limiting conductivity is, for example, less than 5 mS / cm (millisiemens per centimeter), in particular less than 2 mS / cm.

[0029] An additional or further aspect of the present invention provides that the method is performed automatically, i.e., automatically. This means, for example, that the workpiece material is guided continuously or discontinuously from one method step to the next, with the method steps preferably occurring essentially parallel to one another in time. This increases the throughput for the recycling of electroplated plastics.

[0030] An apparatus according to the invention is provided, suitable and configured for carrying out the above-mentioned method, the apparatus being specifically designed for the recycling and reprocessing of workpieces made of electroplated plastics.

[0031] The apparatus comprises, for example, a crushing device for pre-crushing the workpieces into workpiece granules, which crushing device is, for example, configured as a cutting mill, a shredder or a cross-flow shredder.

[0032] The device comprises a decomposition unit for the submerged discharge decoating of workpieces or workpiece granules. The workpieces are decomposed into plastic granules and coated granules by shock wave treatment with (low) pulse energy. The workpieces or workpiece granules are fed to the decomposition unit using, for example, conveyor technology (belt, suction conveyor).

[0033] The crushed material is discharged from the disintegration unit by a belt or screw conveyor, a water sweeper, an airlift pump (pneumatic lifter), or a combination thereof. The crushed material, or granules, are suspended in the liquid of the disintegration unit during the material discharge. The resulting suspension is then (pre-) dewatered and, for example, dried using a dryer. The dryer may be, for example, a washing screener, a hot air (plastic) granule dryer, a fluidized bed dryer, a centrifugal dryer, or a combination thereof. The raw material for the dryer is essentially a heterogeneous mixture of plastic granules and coated granules. This mixture preferably has a residual moisture content of less than 10% by weight, in particular less than 5% by weight.

[0034] The dried mixture is fed to a magnetic separator, which separates the mixture into plastic granules and coated granules by magnetic separation, for example, in a single-stage or multi-stage magnetic separator, for example, implemented as a magnetic drum or belt magnet, with a magnetic field strength of 1,000 to 25,000 gauss.

[0035] This results in a particularly suitable device for the recycling of electroplated plastic workpieces, which preferably has a processing capacity of 50 kg / h (kilograms per hour) to 500 kg / h of raw material (workpieces, workpiece granules).

[0036] In a preferred embodiment, the decomposition unit includes a comminution reactor for shock wave treatment of workpieces. The comminution reactor comprises a container (comminution container) filled with a liquid, e.g., water, and an impulse power supply. The impulse power supply is conducted into the container by at least two electrodes submerged in the liquid. One of the electrodes is, for example, configured as a ground electrode, and the other electrode is configured as a high-voltage electrode. An underwater spark gap is formed between the electrodes, and during operation, the electrodes generate an impact discharge in the liquid by a high-voltage impulse. The workpieces or workpiece particles are guided through the underwater spark gap. Optionally, the comminution reactor can be closed by a process stabilization flap, which allows the residence time of the material to be comminuted in the comminution container to be set arbitrarily or freely.

[0037] The parameters of the impact discharge, in particular the pulse energy or discharge energy, the value of the high voltage between the electrodes, the repetition frequency of the high-voltage impulses, and / or the electrode arrangement, are selected in the decomposition unit so as to separate the electroplated coating from the plastic. In a preferred embodiment, the operating voltage is, for example, 25 kV to 50 kV, and the pulse energy or discharge energy of the impact discharge is less than 50 J, for example, 2 J to 50 J. The pulse repetition frequency is, for example, set to 10 to 50 discharges per second, and the electrode spacing is, for example, 5 mm to 40 mm.

[0038] In a preferred embodiment, the impulse power supply has at least one electrode stack with three to four (high-voltage) electrodes, which are arranged one behind the other or next to each other along the conveying direction. Preferably, the impulse power supply has one or more electrode stacks, each with three to four electrodes operating in parallel and each with one to four measuring electrodes. The electrode stacks can then be readjusted for process control during the shock wave process by means of an (adjusting) cylinder. In other words, distance adjustment, i.e., changing the distance between the electrode stacks or between the electrodes, is possible. This ensures reliable coating removal of the workpiece or workpiece particles. For scaling purposes, for example, the number of impulse power supplies and / or electrode stacks can be changed.

[0039] An additional or further aspect of the present invention provides that the decomposition unit has a comminution container that houses the comminution reactor. In particular, the sound-insulating and / or EMC-protected cabin of the decomposition unit is formed in the container structure. This ensures a simple and low-cost construction of the decomposition unit.

[0040] The workpieces or granules of workpieces are fed, for example, from the side or through the roof of the grinding container. For this purpose, the roof has, for example, a (filling) nozzle or an opening. Preferably, the workpieces are placed or fed by gravity directly, i.e., directly to each electrode stack, to a group circuit consisting of three to four high-voltage electrodes, between two adjacent electrode stacks, or to the center of the grinding reactor. This places the workpiece to be decoated directly in the area of ​​the highest pressure gradient, thereby ensuring reliable decoating.

[0041] According to the invention, the effect of a submerged discharge is used for the removal of coatings from electroplated plastic workpieces by shock wave treatment, whereby the descriptions relating to the method and / or apparatus also apply to this use, and vice versa, to that effect.

[0042] In the following, an embodiment of the invention will be described in more detail with reference to the drawings. [Brief explanation of the drawings]

[0043] [Figure 1] 1 is a schematic diagram showing an apparatus for recycling and regenerating electroplated plastic workpieces in a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a disassembly unit of the device according to the first embodiment. [Figure 3] FIG. 10 is a perspective view showing a disassembly unit of the device according to the second embodiment. [Figure 4] FIG. 10 is a schematic diagram showing an apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0044] In all figures, corresponding parts and sizes are always provided with the same reference signs.

[0045] FIG. 1 shows a simplified schematic representation of an apparatus 2. The apparatus 2 is configured as a recycling device for the recycling and reprocessing of workpieces 4 made of electroplated plastic. The apparatus design shown in FIG. 1 is configured in this case for an automatic processing capacity of, for example, 100 kg / h of raw material. This means that 100 kg of workpieces 4 per hour can be automatically recycled by the apparatus, either continuously or discontinuously. The following description relates, by way of example, to just one workpiece 4.

[0046] The workpiece 4 is in this case in particular electroplating waste or electroplated plastic made of ABS plastic with a coating of chromium, nickel and / or copper.

[0047] The apparatus 2 in this case has six process or method steps for the regeneration treatment. In the first method step, also referred to below as pre-grinding 6, the workpieces 4 are pulverized into workpiece granules 10 using a cutting mill 8. This achieves homogenization of the input material for the subsequent shock wave treatment. The workpiece granules 10 then have an average particle size of, for example, less than 20 mm.

[0048] The cutting mill 8 is designed to crush the workpiece granules 10, for example, to a mean particle size of less than 20 mm. The cutting mill 8 then has, for example, two rows of crushing rotor knives.

[0049] The workpiece granules 10 preferably have a narrow particle size distribution with an upper particle size limit and a lower particle size limit for further processing. In a second method step, which will hereinafter also be referred to as sieving 12, the workpiece granules 10 are sieved using a sieving machine 14. For example, the sieving machine 14 may be configured as a linear vibrating screen or a round screen / tumbler screen. Coarse particles 16 and fine particles 18 are sieved or removed from the workpiece granules 10 by the sieving machine 14. In this context, fine particles 18 are understood to mean granule fragments having a particle size smaller than the lower particle size limit, for example, less than 1 mm. Correspondingly, coarse particles 16 are understood to mean granule fragments having a particle size larger than the lower particle size limit, for example, larger than 10 mm. The sieved workpiece granules 10' thereby have a particle size distribution of, for example, 1 mm to 10 mm.

[0050] The sieved workpiece granules 10 ′ are fed to a decomposition unit, ie, a shock wave device 22 , in a method step also referred to as decoating 20 .

[0051] The decomposition unit 22 is shown separately in Fig. 2. The decomposition unit 22 is provided, suitable and configured for removing coatings from the workpiece granules 10' in this case by submerged discharge effects. In particular, the decomposition unit 22 is suitable and configured for continuous shock wave treatment with low pulse energy.

[0052] The decomposition unit 22 in this case comprises a comminution reactor (not shown in detail) for removing coatings from the workpiece granules 10' by shock wave treatment. The comminution reactor then comprises a container (comminution container) filled with a liquid, e.g., water, and at least one impulse power supply. The impulse power supply is guided into the container by at least two electrodes immersed in the liquid. One of the electrodes is, for example, configured as a ground electrode, and the other electrode is configured as a high-voltage electrode. The impulse power supply preferably comprises three to four (high-voltage) electrodes, which are arranged as an electrode stack. The decomposition unit 22 may, for example, comprise multiple impulse power supplies, each of which comprises one or more electrode stacks with three to four high-voltage electrodes. The electrode stack can then be readjusted by an (adjustment) cylinder during the shock wave process for process control.

[0053] By varying the number of impulse power supplies and / or the number of high voltage electrodes, the decomposition unit 22 can be easily and appropriately scaled with respect to the desired processing capacity.

[0054] An underwater spark gap is formed between the electrodes, and during operation the electrodes generate high voltage impulses that generate shock discharges in the liquid that remove the coating from the workpiece particles 10'. The workpiece particles 10' are then guided through the underwater spark gap.

[0055] The parameters of the impact discharge, in particular the pulse energy or discharge energy, the value of the high voltage between the electrodes, the repetition frequency of the high voltage impulses, and / or the arrangement of the electrodes, are selected so that the electroplated coating is separated from the plastic in the decomposition unit. In a preferred embodiment, the high voltage is less than 50 kV, and the pulse energy or discharge energy of the impact discharge is less than 50 J, for example, 5 J to 50 J.

[0056] The grinding reactor is enclosed in a grinding container 24 as a soundproof enclosure. The noise level during operation of the decomposition unit is preferably less than 85 dB(A). A control cabinet 26, which houses the control electronics for at least one impulse power supply, e.g., a programmable logic controller (PLC), is located adjacent to the grinding container 24. The impulse power supply, or (impulse current) generator, is housed in a generator cabinet, not shown in detail, located separately from the control cabinet 26.

[0057] The disintegration unit 22 has a conveyor device 28 configured as a suction conveyor for feeding the material, which conveyor device 28 guides the workpiece granules 10' via a ramp to an opening in the roof of the crushing container 24. Preferably, the workpiece granules 10' are positioned or fed by gravity directly to each electrode stack, which is a group circuit consisting of three to four high-voltage electrodes, between two adjacent electrode stacks or in the center of the crushing reactor. As a result, the workpiece granules 10' to be decoated are fed directly to the area with the highest pressure gradient, thereby ensuring reliable decoating.

[0058] FIG. 3 shows a second embodiment of the disintegration unit 22'. Compared to the previous embodiment, the disintegration unit 22' in this case has a larger grinding container 24'. For example, the grinding container 24' is four times larger than the grinding container 24. In one size considered, the grinding container 24 is formed as a 10-foot container, while the grinding container 24' is formed as a 40-foot container. The 10-foot container has, for example, a throughput of 100 kg / h, while the 40-foot container has, in particular, a throughput of approximately 500 kg / h. The disintegration unit 22' has, for example, two control cabinets 26. The conveyor device 28 of the disintegration unit 22' is formed, for example, as a belt conveyor.

[0059] Discharge of the comminuted material from the disintegration units 22, 22' can be by belt or screw conveyors, water flushing, air lift pumps, or combinations thereof.

[0060] The decomposition unit 22 produces a suspension as raw material. The suspension is then composed of the liquid 30 of the grinding reactor and the decoated components 32, 34 of the workpiece granules 10'. In particular, the suspension in this case comprises plastic granules 32, i.e., granules of a plastic component, and coated granules 34, i.e., granules consisting of metal fragments with an electroplated coating and plastic chips with residual coating.

[0061] The suspension is dewatered and dried in a subsequent method step, also referred to hereinafter as drying and dewatering 36, using a dryer 38. During dewatering 36, the liquid 30 is separated from the solid components 32, 34. Preferably, a sieving step is carried out, and if necessary, a washing step can be added, to separate the metal-rich fines of the coating granules 34. The fines are then formed by the metal fraction 40, i.e., metal fragments of the electroplated coating having a particle size of less than 1 mm.

[0062] The drying / dewatering part of the subsequent drying and dewatering 36 comprises, for example, a centrifuge for producing a residual moisture content of less than 5% by weight. For this purpose, the dryer 38 is formed, for example, as a centrifugal dryer, which separates the liquid 30 from the components 32, 34 by centrifugal dewatering. Preferably, the dryer 38 comprises, in this case, a sieve drum for the integrated separation of the residual fines or metal fraction 40.

[0063] Alternatively, the dryer 38 can be configured as a dewatering sieve. In this case, the dryer 38 is configured in particular as a linear vibrating sieve having three sections. The first section has an integrated cleaning nozzle for cleaning. In the second section, sieving and pre-dewatering take place in order to separate all particles smaller than 2 mm. In the third section, the granules 32, 34 are dried using a hot air blower.

[0064] The third section for hot air drying can be formed as a separate linear vibrating screen, which means that the first two sections of the dryer 38 are arranged in one unique vibrating screen for pre-dewatering, and the third section of the dryer 38 is arranged in a separate linear vibrating screen with hot air drying.

[0065] The raw material for drying and dewatering 36 is a heterogeneous mixture of plastic granules 32 and coated granules 34. This mixture preferably has a residual moisture content of less than 10% by weight, in particular less than 5% by weight.

[0066] The liquid 30 discharged from the dryer 38 during the dewatering process is preferably returned to the decomposition unit. For this purpose, the liquid first passes through a wastewater reclamation system for solids separation. For this purpose, a solids separator (not shown in detail) is provided, which separates coarse and fine particle components, such as the metal fraction 40, from the liquid. The solids separator is configured, for example, as a gradient filter or a vacuum belt filter. When the liquid 30 reaches a limiting conductivity, it is discarded and replaced with new liquid.

[0067] The dry mixture is separated by a magnetic separator 42 into non-magnetic plastic granules 32 and (at least partially) magnetic coated granules 34 in a method step of magnetic particle separation 44. In other words, the dry mixture is fed to the magnetic separator 42, which separates the mixture by magnetic separation into a magnetic fraction (coated granules 34) consisting of peeled coatings and plastic granules with residual coatings, and a non-magnetic fraction (plastic granules 32) of plastic chip material having a purity of more than 99% by weight.

[0068] The single-stage or multi-stage magnetic separator 42 is implemented, for example, as a magnetic drum or (hanging) belt magnet. In particular, the magnetic separator has a magnetic field strength of 3500 G to 20000 G. In this case, the mixture is fed, for example, via a vibrating chute, with continuous separation of magnetic particles, such as granules with removed metal coating and residual coating.

[0069] Preferably, in this case, the separated granules with the residual coating of the coated granules 34 are returned to the decomposition unit 22, whereupon the metal granules of the coated granules 34 can be further processed as recycled material.

[0070] The pure (non-magnetic) plastic products or plastic granules 32 have a purity of more than 99% by weight, for example more than 99.9% by weight. The plastic granules 32 are then filled by a filling station 48 in a method step called filling 46. In particular, big-bag filling of the plastic granules 32 is performed here.

[0071] The device 2' shown in Figure 4 generally corresponds to the above description, with the addition of a supply station 50 for a material supply 52 of workpieces 4, which is located upstream of the pre-grinding 6.

[0072] The system 2' may further include an optional wastewater reclamation system 54 for process water reclamation 56, which separates dissolved components from the liquid 30 of the dryer 38, thereby allowing the introduction of a reclaimed or purified liquid 30', which is returned to the decomposition units 22, 22'.

[0073] The invention is not limited to the above-described embodiments. On the contrary, other variants of the invention can be derived by those skilled in the art without departing from the subject matter of the invention. In particular, furthermore, all the individual features described in connection with the examples can also be combined with one another in other ways without departing from the subject matter of the invention. [Explanation of symbols]

[0074] 2,2' device 4 workpieces 6 Preliminary crushing 8 Cutting Mill 10,10' Workpiece Granular 12 Sifting and sizing 14 Sieving machine 16 Coarse grain 18 fine grain 20 Film removal 22 Decomposition Unit 24,24' crushing container 26 Control Cabinet 28 Conveyor equipment 30,30' liquid 32 Plastic granules 34 Coated particles 36 Drying and dehydration 38 Dryer 40 Metal Fraction 42 Magnetic Separator 44 Magnetic Particle Separation 46 Filling 48 filling stations 50 Supply Stations 52 Material supply 54 Wastewater reclamation treatment equipment 56 Process water reclamation treatment

Claims

1. A method for the recycling and reprocessing of electroplated plastic workpieces (4), comprising: Decoating the workpieces (4) by a decomposition unit (22, 22') using a submerged discharge effect to produce a suspension containing plastic granules (32) and coated granules (34); dehydrating the suspension; and separating the plastic granules (32) from the coated granules (34) by magnetic separation using a magnetic separator (42); The decomposition unit (22, 22') comprises a pulverization reactor having a container filled with liquid and an impulse power supply having at least two electrodes submerged in the liquid, and in the coating removal process by the decomposition unit (22, 22'), an underwater spark gap is formed between the two electrodes, and the underwater spark gap generates an impact discharge in the liquid by a high-voltage impulse, and the pulse energy or discharge energy of the impact discharge is less than 50 J at a high voltage of less than 50 kV.

2. 2. The method of claim 1, wherein the plastic granules (32) are of sufficient purity for direct recycling or direct reintroduction in the production of electroplated plastics.

3. 3. The method according to claim 2, characterized in that the plastic granules (32) have a purity of more than 99% by weight.

4. 2. A method according to claim 1, characterized in that the workpieces (4) are crushed into workpiece granules (10) before being fed to the disintegration unit (22, 22').

5. 2. A method according to claim 1, characterized in that the liquid (30, 30') of the suspension is returned to the decomposition unit (22, 22') in the course of dewatering (36).

6. 10. The method of claim 1, wherein the method is performed automatically.

7. An apparatus (2, 2') for carrying out the method according to claim 6, comprising: the decomposition unit (22, 22') for removing coatings from the workpiece (4) by means of a submerged discharge effect; a dryer (38) for dewatering the suspension containing the plastic granules (32) and the coated granules (34) coming out of the decomposition unit (22, 22'); and a magnetic separator (42) for magnetically separating the plastic granules (32) from the coated granules (34).

8. 8. The device (2, 2') according to claim 7, characterized in that the impulse power supply comprises at least one electrode stack with 3 to 4 electrodes.

9. 9. Apparatus (2, 2') according to claim 8, characterized in that the number of said impulse power sources and / or the number of said electrode stacks are variable.

10. 8. Apparatus (2, 2') according to claim 7, characterized in that the decomposition unit (22, 22') comprises a comminution container (24, 24') for accommodating the comminution reactor.

11. 11. The apparatus (2, 2') according to claim 10, characterized in that the workpieces (4) are fed through the roof of the grinding container (24, 24') so that they are brought by gravity directly in front of the electrodes of the grinding reactor.

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