PROCESS FOR RECOVERING PLASTICS

Description

[0001] The invention relates to a process for the recovery of plastics from a mixture of at least two polymers, wherein one polymer is present in a proportion of 1 to 99 wt.%.

[0002] To reduce waste volumes, it is recommended that as large a proportion of the waste generated as possible be recycled and returned to the recycling cycle. The recycling and recirculation of components from waste electrical and electronic equipment, especially less valuable plastic components, is particularly problematic. Due to incomplete recycling, particularly of halogen-containing plastics, and suboptimal recycling after waste treatment, waste electrical and electronic equipment causes significant damage to the ecosystem.

[0003] The complexity of the plastics composition presents a particular challenge, particularly when it comes to the desired recycling of plastics from waste electrical and electronic equipment. For example, one of the most common waste treatment methods, namely separation based on density, leads to unsatisfactory results for waste electrical and electronic equipment. At densities of less than 1 g / cm³, in addition to polyolefins, particularly low- and high-density polyethylene (LDPE, HDPE), polypropylene homopolymers and copolymers, polyurethane foams, polyvinyl chloride foams, wood, paper, biofibers, and other components are found. A similarly diverse composition can also be found at higher densities. For example, at a density fraction of 1.00 to 1.05 g / cm³, in addition to the desired high-impact polystyrene fractions (HIPS), filled polypropylene types, flame-retardant polypropylene types, and polyamides (PA), particularly PA 6.10, PA 6.12, PA 11, and PA 12, are found.At even higher densities, polybutylene terephthalate (PBT) is found both at densities above 1.4 g / cm³, where polyoxymethlenes (POM), particularly POM-h and POM-c, are separated, and at densities below 1.3 g / cm³, where flame-retardant polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) are separated. Due to its wide variety of variants, PVC is found in all density ranges and is highly likely to carry plasticizers and heavy metals into these ranges.

[0004] In addition to density separation, near-infrared sorting machines (NIR sorters) are also often used for separation. However, due to the technical requirements of electrical appliances, the most common color is black due to the carbon black they contain. The carbon black guarantees an antistatic or conductive surface to make electrical appliances safer. Unfortunately, NIR sorters cannot detect plastics filled with soot and therefore cannot sort them. The electrostatically altered properties of the plastics also often make separation with electrostatic sorting machines more difficult. For this reason, there is still no perfect process for efficiently and completely reprocessing old electrical appliances. Significant portions of old electrical appliances are either incinerated or illegally disposed of.

[0005] Even recycled plastics are generally only found in downcycling applications such as street sign bases, park benches, or coat hangers, but not in new electrical appliances. The reason for this is that not only is there no perfect process for separation, but also a corresponding process for compounding into granules for the plastics processing industry. Due to a lack of purity, outdated plastics, often manufactured up to 40 years ago, and aging through use of the electrical appliances, the properties of the recycled plastics do not meet the requirements of the modern electronics industry. All extruders currently offered for compounding recycled plastics are designed for mass waste streams, such as packaging or plastic bottles. Current processing and production processes for plastics from waste electrical appliances are not coordinated.When it comes to recycling waste electrical and electronic equipment, the focus is currently not on recycling plastics, but on recovering metals.

[0006] Generally, the processing of waste electrical and electronic equipment (WEEE) begins with the manual dismantling of valuable or harmful components, such as circuit boards for the recovery of precious metals, cables for the recovery of copper, or batteries for the recycling of mercury, lithium, or cadmium. The remaining fraction contains, in addition to housings and components made of metal or plastic, small electronic components and plastic components made of a variety of different plastics. The bulk consists of various metals, and the bulk consists of various plastics. High-impact polystyrene (HIPS) and polyacrylonitrile butadiene styrene (ABS) represent the largest proportion, accounting for approximately 50% of the plastics.In addition to HIPS and ABS, the plastics also include up to 10% polypropylene (PP) and a large number of smaller proportions of other thermoplastics, elastomers and thermosets, of which polyamides (PA) with a share of about 5% and polycarbonates (PC) with a share of about 3% are the most important.

[0007] The metals are usually separated in dry processes using magnets and eddy current separators. Copper and smaller circuit boards are also separated using color sorting systems. What remains is a plastic-rich mixture containing HIPS, ABS, and PP as easily recyclable components. Currently, this plastic-rich mixture is usually broken down in wet processes using density separation, with the disadvantages mentioned above. Due to the foreign components usually contained in the individual components obtained through density separation, these cannot be returned to the cycle as equivalent plastic. Due to their large surface area, foams in particular transport a variety of value-reducing contaminants, such as traces of heavy metals, POPs (persistent organic pollutants), or unpleasant odors, into the recyclate.This can therefore only be used in so-called downcycling for lower-quality products.

[0008] The heavy fraction obtained during density separation contains the styrene-based polymers HIPS and ABS, which are further separated, for example, by triboelectric or spectroscopic sorting. However, all known processes ignore the fact that the plastics used in electronic devices are usually heavily additive-rich or are used as highly complex compounded blends with very specific properties, particularly with regard to aging, conductivity, strength, flowability, sound absorption, or chemical resistance. This ignoring of the complexity of the plastic mixture results in approximately half of the plastic-rich mixture being lost as a complex waste mixture, reducing the efficiency and yield of the processes.

[0009] Processes for recovering plastics from the recycling of waste electrical and electronic equipment are described, for example, in WO-A 2006 / 131377, WO-A 2014 / 130546 or EP-A 2 163 369.

[0010] A process for separating different polymers from waste by means of density separation is known, for example, from US-B 6,460788.

[0011] The disadvantage of all known processes, however, is that the separation steps used either lead to insufficient separation and thus to contaminated fractions or, in the case of sufficient separation, as can be achieved by the process described in EP-A 2 163 369, to a loss of plastics of 20 to 40% due to the complex size reduction steps.

[0012] The object of the present invention is therefore to provide a process which achieves a separation of the plastics in such a way that efficient recycling is possible and the plastics obtained can be used not only in downcycling processes and in which the proportion of plastics lost is also minimized.

[0013] This object is achieved by a process for the recovery of plastics from a mixture of at least two polymers, wherein one polymer is present in a proportion of 1 to 99 wt.%, comprising: (a) performing a first density separation at a density in the range of 1.14 to 1.18 g / cm 3 , obtaining a first light fraction containing polyolefins and styrene-based polymers and a first heavy fraction; (b) feeding the first light fraction to a second density separation at a density in the range of 1.00 to 1.03 g / cm 3 , obtaining a second light fraction containing unfilled polyolefins and a second heavy fraction containing styrene-based polymers and optionally filled polyolefins; (c) feeding the first heavy fraction to a third density separation at a density in the range of 1.18 to 1.24 g / cm 3 , wherein the first heavy fraction is separated into a third light fraction containing polyamides, polycarbonates and methacrylate-based polymers, and a third heavy fraction containing polyoxymethylene, highly filled polymers and halogen-containing polymers;(d) separating all fractions into fractions containing essentially pure polymers; whereby metal-containing components are removed from the first heavy fraction before the third density separation.

[0014] Surprisingly, it has been shown that the first density separation at a density in the range of 1.14 to 1.18 g / cm³ maximizes the proportion of styrene-based polymers, particularly HIPS and ABS, and polyolefins, particularly PP, that can be recovered from the mixture by the process, compared to known processes in which the density separation is carried out to separate styrene-based polymers at a density of 1.08 g / cm³. Furthermore, it has been shown that, despite the comparatively high density of the first density separation, the halogen content, particularly the proportion of bromine from brominated flame retardants, does not increase.

[0015] According to the invention, a first density separation is initially carried out at a density in the range from 1.14 to 1.18 g / cm 3 , preferably at a density in the range from 1.14 to 1.17 g / cm 3 and in particular at a density in the range from 1.15 to 1.16 g / cm 3 , for example a density of 1.15 g / cm 3 , at which the first heavy fraction and the first light fraction are obtained. As a result of the density separation at a comparatively high density, the first light fraction also contains styrene-based polymers which, due to their additivation, have a higher density than usual. As a result, a much larger proportion of styrene-based polymers can be recovered from the plastic mixture than with the processes known from the prior art.Compared to the processes known from the prior art, the proportion of styrene-based polymers obtained by the first density separation at a density in the range of 1.14 to 1.18 g / cm 3 can be up to twice as large.

[0016] The first heavy fraction contains in particular waste materials and metals as well as a proportion of polymers with a high density, in particular plastics containing halogen compounds, for example polyvinyl chloride (PVC) or polymers with brominated flame retardants, plastics with a high proportion of fillers, for example carbon fibers or glass fibers, as well as polycarbonates (PC) and plastic blends containing polycarbonate, for example PC / ABS or PC alloys, polyamides, in particular PA6 to PA12, and polymethacrylates, for example polymethyl methacrylate (PMMA) or methacrylate alloys.

[0017] To separate the styrene-based polymers and the polyolefins from the first light fraction, the latter is subjected to a second density separation. The second density separation is carried out at a density in the range of 1.00 to 1.03 g / cm 3 , preferably at a density in the range of 1.00 to 1.02 g / cm 3 , and in particular at a density in the range of 1.00 to 1.01 g / cm 3 , for example a density of 1.00 g / cm 3 . The second density separation yields a second heavy fraction containing the styrene-based polymers, in particular HIPS and ABS, and optionally filled polyolefins, and a second light fraction containing unfilled polyolefins, in particular PP.

[0018] For both the first density separation (a) and the second density separation (b), all processes for density separation known to those skilled in the art can be used. For example, the density separation can be carried out in a cyclone or in a sink-float system. If a sink-float system is used, it contains a liquid with the density at which the feed mixture is to be separated. The components whose density is greater than the density of the liquid sink, and the components with a density lower than the density of the liquid float to the top. The liquid used can be water, for example, to which an appropriate amount of salt, in particular sodium chloride, is added to adjust the density.

[0019] When performing density separation in a float-sink system, it may be advisable to dry the particles of the individual fractions before they are sent to further processing steps. This can prevent, for example, entrained liquid containing moist particles from changing the density of the liquid in a subsequent float-sink system, or inaccurate results from adhering liquid in other processes.

[0020] Particularly with density separation in a sink-float system, the separation success is independent of the size of the individual particles contained in the mixture of at least two polymers. For this reason, a prior comminution process can be omitted. With density separation in a sink-float system, the heavy fraction is removed from the bottom of the sink-float system and the light fraction from the surface of the liquid. For this purpose, a weir can be used, for example, over which the liquid flows, whereby the light fraction flows with the liquid over the weir and can then be separated from the liquid. The liquid can then be returned to the sink-float system.

[0021] When the heavy fraction is removed from the sump, liquid is usually also removed, so the heavy fraction must first be separated from the liquid. Here, too, the liquid can then be returned to the float-sink system.

[0022] Any device for solid / liquid separation known to those skilled in the art can be used to separate the heavy or light fractions from the liquid. Separation can be achieved, for example, using a filter or a centrifuge. Separation using sieves is also possible, although the mesh size of the sieves must be smaller than the smallest particles contained in the mixture to prevent the small particles from concentrating in the liquid. Alternatively, to prevent the concentration of foreign substances or small particles, a portion of the liquid can be regularly or continuously removed from the process and replaced with fresh liquid. The removed liquid can then either be purified and disposed of or processed and returned to the process.

[0023] Particularly in density separation using a cyclone, it is advantageous to perform a comminution step prior to density separation, producing particles with an average grain size of 3 to 300 mm, more preferably 5 to 200 mm, and especially 7 to 150 mm. However, due to possible subsequent processing steps, it is also advisable to perform such a comminution step when density separation is performed in a sink-float system.

[0024] If drying is to be carried out before a subsequent step, any suitable dryer can be used, although continuous dryers are preferred. Warm air dryers are preferably used for drying, and these are operated at temperatures below the glass transition temperature or decomposition temperature of the individual components contained in the mixture to be separated.

[0025] Since the first heavy fraction separated in the first density separation (a) may still contain plastics, in particular polyamides, polycarbonates, methacrylate-based polymers, highly filled polymers and halogen-containing polymers, the first heavy fraction is fed to a third density separation at a density in the range from 1.18 to 1.24 g / cm 3< , more preferably at a density in the range from 1.19 to 1.24 g / cm 3< , further preferably at a density in the range from 1.20 to 1.23 g / cm 3< and in particular at a density in the range from 1.21 to 1.22 g / cm 3<.

[0026] In the third density separation, the first heavy fraction is a third light fraction containing polyamides, polycarbonates and methacrylate-based polymers and a third heavy fraction containing polyoxymethylene, highly filled polymers and halogen-containing polymers.

[0027] The third density separation, like the first or second density separation, can be carried out in any density separation system known to the person skilled in the art, for example a sink-float system or a cyclone.

[0028] Since the first heavy fraction may contain, in addition to the high-density polymers, other inorganic components with a density higher than the density at which the first density separation is carried out, for example metal-containing components, the metal-containing components are removed before the third density separation.

[0029] The metal-containing components can be removed by any method known to those skilled in the art. For example, it is possible to separate the metal-containing components by density separation, whereby the density must be selected such that the heavy plastic components, especially highly filled polymers, remain in the light fraction and are not separated. Furthermore, it is also possible to separate magnetic or magnetizable metallic components, especially iron-containing components, from the plastics by magnetic separation.

[0030] In order to remove the metal-containing components from the first heavy fraction, it is particularly preferred to process the first heavy fraction (i) is separated into a coarse fraction and a fine fraction, (ii) any inorganic and metallic components are removed from the coarse fraction, (iii) the coarse fraction is comminuted, (iv) the fine fraction and the comminuted coarse fraction are then mixed together again to form a first heavy, metal-free fraction, and (v) the first heavy, metal-free fraction is freed from the fines.

[0031] Water tables, for example, are used, for example, to separate composite parts containing metal, such as circuit boards. These can be followed by further sorting steps. For efficient separation using a water table, it is necessary that the particles of the mixture to be separated are smaller than the spacing between the water table's webs. For this reason, the first heavy fraction is first fed to a classifier and separated into a coarse metal-containing fraction and a fine plastic- and wood-rich fraction. The coarse fraction contains almost all particles whose grain size is larger than the web spacing of the water tables used. The particles of the fine fraction have a grain size that is smaller than the web spacing of the water tables used.The first heavy, metal-free fraction is forced into the classifier into an upflow of water with a density of 1 g / cm³ or a mixture with a density greater than 1 g / cm³ containing salt, clay, or iron powder. Forced conveying ensures that the particles of the first heavy, metal-free fraction are completely wetted, allowing for efficient separation of the plastic particles from the composite particles.

[0032] Since metal parts such as ball bearings, screws, nails, or even stones contained in the coarse fraction can cause damage to the grinding mechanism of downstream mills, it is preferable to separate the inorganic and metallic components from the coarse fraction before it is crushed. Air classifiers, for example, can be used to separate the inorganic components from the coarse fraction.

[0033] Any mill known to those skilled in the art can be used to comminute the coarse fraction, although cutting mills are preferred. In the mill, the particles of the coarse fraction are comminuted so that their size is no larger than the mesh width of the water tables used and corresponds to the maximum permissible size for downstream sorting systems. When using a cutting mill, a cutting screen is used for this purpose, the mesh width of which is matched to the mesh width of the water tables used, i.e. preferably corresponds to the mesh width of the water tables used. The particles comminuted in the cutting mill that are smaller than the mesh width of the cutting screen fall through it and can be removed from the cutting mill. Particles that are larger than the mesh width of the cutting screen remain in the mill and are further comminuted.

[0034] Even when using other comminution devices, especially other types of mills, only the particles that are smaller than the web width of the wash basins used are removed and the remaining particles are further crushed.

[0035] The coarse fraction thus crushed can then be mixed again with the fine fraction if the fine fraction is very rich in metals, for example in the form of cable pieces and copper strands, and fed together to the subsequent water tables.

[0036] This material stream, which essentially contains the composite particles containing filled polycarbonates, is fed to at least one, preferably two, serially operating water tables, where it is separated into a waste fraction, a metal-rich fraction, and a plastic fraction consisting of a complex composition of various plastics. In particular, the plastic fraction obtained here contains a large number of different plastics that are highly relevant for technical applications.

[0037] After separation of the metal-containing components, the first heavy, metal-free fraction thus obtained is fed to the third density separation, in which the third light fraction and the third heavy fraction are obtained.

[0038] After performing the first density separation (a), the second density separation (b), and the third density separation (c), all fractions obtained in the density separations are separated into fractions containing essentially pure polymers. The separation into the fractions containing essentially pure polymers can be carried out by any method known to the person skilled in the art.

[0039] In order to obtain essentially pure plastics, the second heavy fraction is preferably a fraction containing essentially styrene-based polymers and a fraction containing essentially filled polyolefins.

[0040] The separation of the second heavy fraction is preferably carried out by means of at least one triboelectric sorting, by means of at least one spectroscopic sorting or a combination of triboelectric and spectroscopic sorting.

[0041] In triboelectric sorting, the individual plastic particles are electrostatically charged through friction and can then be separated from each other in a high-voltage field due to their different charges.

[0042] In spectroscopic sorting, the individual types of plastic are usually separated from one another using near-infrared (NIR) spectroscopy or UV spectroscopy.

[0043] Both triboelectric sorting and spectroscopic sorting can be carried out using equipment for triboelectric sorting or spectroscopic sorting that is known to the person skilled in the art and available on the market. Spectroscopic sorting systems should also be designed, in particular, to be able to detect carbon black-colored plastics.

[0044] From the second light fraction obtained in the second density separation (b), light materials and waste materials are preferably first separated. The light materials and waste materials are non-polymeric impurities, such as paper or other foreign matter whose density is below the density of the polymers in the second light fraction. In this way, a fraction containing essentially unfilled polyolefins is obtained.

[0045] The separation of light materials and waste materials can also be carried out in at least one triboelectric sorting process, at least one spectroscopic sorting process or a combination of triboelectric and spectroscopic sorting.

[0046] By further sorting the second heavy fraction and the second light fraction obtained in the second density separation, the fraction containing essentially styrene-based polymers, the fraction containing essentially filled polyolefins and the fraction containing essentially unfilled polyolefins are obtained as fractions containing essentially pure polymers.

[0047] Since the third light fraction obtained in the third density separation contains several different plastics, in particular polyamides, polycarbonates and methacrylate-based polymers as well as highly filled polyolefins, in particular talc-containing polypropylene, the third light fraction is preferably a fraction essentially containing highly filled polyolefins, a fraction essentially containing polyamides, a fraction essentially containing polycarbonate and a fraction essentially containing methacrylate-based polymers are separated to obtain fractions essentially containing pure polymers.

[0048] The separation of the third light fraction into the fraction containing essentially polyamides, the fraction containing essentially polycarbonate and the fraction containing essentially methacrylate-based polymers as well as the fraction containing essentially highly filled polyolefins is also preferably carried out in at least one triboelectric sorting, at least one spectroscopic sorting or a combination of triboelectric sorting and spectroscopic sorting.

[0049] In order to also separate the third heavy fraction obtained in the third density separation, containing polyoxymethylene, highly filled polymers and halogen-containing polymers, into fractions containing essentially pure polymers, this is preferably a polyoxymethylene-containing fraction, a filled polymer-containing fraction, a bromine-containing fraction and a fraction containing essentially chlorine-containing polymers.

[0050] Here too, the separations of the third heavy fraction containing polyoxymethylene, highly filled polymers and halogen-containing polymers into the polyoxymethylene-containing fraction, the filled polymer-containing fraction, the bromine-containing fraction and the fraction containing essentially chlorine-containing polymers are carried out in each case in at least one triboelectric sorting, at least one spectroscopic sorting or combinations of triboelectric and spectroscopic sorting.

[0051] The fractions obtained by separating the second heavy fraction, the third light fraction and the third heavy fraction by means of at least one triboelectric sorting, at least one spectroscopic sorting or combinations of triboelectric and spectroscopic sorting, as well as the fraction obtained from the second light fraction after separation of the light materials and waste materials, namely the fraction containing essentially styrene-based polymers, the fraction containing essentially filled polyolefins, the fraction containing essentially unfilled polyolefins, the fraction containing essentially polyamides, the fraction containing essentially polycarbonates, the fraction containing essentially methacrylate-based polymers, the fraction containing polyoxymethylene, the fraction containing filled polymers, the bromine-containing fraction and the fraction containing essentially chlorine-containing polymers are also referred to as "fraction containing essentially pure polymers" if several of these fractions or all of these fractions are meant.

[0052] In addition to the polymers predominantly contained in the fractions containing essentially pure polymers, elastomers may also be present, which are separated from the fractions containing essentially pure polymers in one or more subsequent processing steps. The separation of the thermoplastic elastomers can be carried out using an elastomer separator known to those skilled in the art and is carried out before subsequent process steps, for example, extrusion.

[0053] To produce granules or other semi-finished products, the fractions containing essentially pure polymers are preferably extruded. To remove solid impurities such as thermosets, but also highly cross-linked and non-thermoplastic elastomers, which may still be present in the fractions containing essentially pure polymers and which were entrained by the preceding separation steps, melt filtration, for example, can be used. After melt filtration, in which the undesirable components, namely the solid or elastic components, are separated, the resulting plastic melt is extruded into the desired granules or semi-finished product.

[0054] Since the fractions containing essentially pure polymers may contain, in addition to solid and elastic components, also components that are volatile or that can decompose into volatile components, it is further preferred if these volatile components or components that decompose into volatile components are separated during extrusion under negative pressure by one or more vacuum devolatilizations. Characteristic of this vacuum devolatilization is a pressure of less than 100 mbar(abs), preferably less than 50 mbar(abs), and for special separation tasks a pressure of less than 10 mbar(abs) and for very special separation tasks a pressure of less than 1 mbar(abs). Substances that can be reduced to the detection limit in this way are, in particular, phthalates and brominated flame retardants. Vacuum devolatilization at a pressure of less than 100 mbar is suitable for drying the melt in the extruder.To handle vacuum condensate produced in this way, appropriate chemically resistant, automated filling and transport devices must be provided.

[0055] By separating the volatile components, the components that decompose into volatile components, the solid components, and the elastic components, polymers are obtained during extrusion that are essentially free of undesirable components. Therefore, the polymers obtained in this way can also be used for high-quality products, enabling not only downcycling but also a circular process in which the polymers are used for products that are equivalent to those for which the original, factory-fresh polymers were used.

[0056] Since the individual plastics can be colored in the various fractions, which essentially contain single-variety polymers, it is necessary, especially for a recycling process in which the polymers are used to manufacture high-quality products, to separate the respective fractions containing essentially single-variety polymers into fractions of different colors before further processing into granules. If the polymers are used for light or black products, it is sufficient to separate them into "light" and "dark." If they are used for colored products, it is necessary to sort them according to different colors. This sorting can be performed using commercially available color sorters.

[0057] An embodiment of the invention is illustrated in the figures and is explained in more detail in the following description.

[0058] They show: Figure 1 shows a first strand of the process according to the invention; Figure 2 shows a second strand of the process according to the invention; Figure 3 shows an alternative sorting in the second strand of the process according to the invention.

[0059] Figure 1 shows a first strand of the process according to the invention for the recovery of plastics.

[0060] To recover plastics, a waste fraction 1 is fed to a first density separation 3. The waste fraction 1 is generally a WEEE (Waste of Electrical and Electronic Equipment) waste fraction that has been pretreated by a primary waste treatment and metal recycling plant and predominantly contains materials with a density of more than 1.4 g / cm3. The particles of the waste fraction 1 can be of any size, but it is preferred if the waste fraction 1 has a grain size in the range of 3 to 300 mm, more preferably 5 to 200 mm, and in particular 7 to 150 mm.

[0061] The density separation 3 takes place at a density in the range of 1.14 to 1.18 g / cm 3 , preferably at a density in the range of 1.14 to 1.17 g / cm 3 , and in particular at a density in the range of 1.15 to 1.16 g / cm 3 , and can be carried out, for example, in a sink-float system or a cyclone. During the density separation, a first light fraction 5, containing polyolefins and styrene-based polymers, and a first heavy fraction 7 are obtained.

[0062] Surprisingly, it has been shown that by increasing the density for the first density separation 3 compared to the density commonly used for the density separation according to the state of the art, a significant increase in the content of styrene-based polymers, particularly ABS and PS, in the first light fraction 5 is achieved. This is shown as an example for various densities in Table 1. By increasing the density at which the separation is carried out in the first density separation 3, the yield of styrene-based polymers can be almost doubled. Table 1: Yield of ABS and PS with increasing density cuts Density (g / cm 3 ) ABS and PS yield (%) 1,08 23,2 1,10 30,4 1,15 41,3

[0063] After the first density separation 3, a light waste fraction 9 with a density of less than 1.15 g / cm3 can be added to the first light fraction 5. The light waste fraction 9 preferably also comprises WEEE waste.

[0064] In particular, if the first density separation 3 is carried out in a sink-float system, it is preferred if the first light fraction 5 is dried in a drying step 11 before it is fed to a second density separation 13. Drying prevents larger quantities of liquid with a higher density from being introduced into the second density separation 13 and, if the second density separation 13 is also carried out in a sink-float system, from unduly increasing the density of the liquid in the second density separation 13. If the second density separation 13 is carried out in a cyclone, the adhering liquid of the first density separation 3 can lead to an increase in the density of the particle, so that it is incorrectly separated in the second density separation 13.For this reason, the first light fraction is preferably dried in the drying step 11, regardless of the type of second density separation 13, if the first density separation 3 was carried out in a sink-float system.

[0065] The second density separation 13 can, like the first density separation, be carried out in a sink-float system or a cyclone, wherein the first light fraction 5 is separated in the second density separation 13 at a density in the range from 1.00 to 1.03 g / cm 3 , more preferably at a density in the range from 1.00 to 1.02 g / cm 3 and in particular at a density in the range from 1.00 to 1.01 g / cm 3 into a second light fraction 15 and a second heavy fraction 17. The second light fraction predominantly contains unfilled polyolefins, in particular polypropylene, and the second heavy fraction contains in particular styrene-based polymers such as HIPS and ABS and optionally filled polyolefins, in particular filled polypropylene.

[0066] For further separation into fractions containing essentially pure polymers, the second light fraction 15 can be dried in a second drying step 19. After the second drying step 19, the second light fraction 15 is fed to a first sorting step 21, in which waste materials 23 are separated from the second light fraction 15. The waste materials 23 separated in the first sorting step are, in particular, electrostatic contaminants, especially wood.

[0067] From the second light fraction, which has been freed of waste materials, light materials 27 are then separated in a second sorting stage 25, resulting in a fraction 29 containing essentially unfilled polyolefins. The separated light materials 27 are, in particular, films, fluff, and foams.

[0068] The first sorting step 21 for separating the waste materials 23 and the second sorting step 25 for separating the lightweight materials 27 can each independently be at least one triboelectric sorting step, at least one spectroscopic sorting step, or a combination of triboelectric sorting and spectroscopic sorting. Preferably, both the first sorting step 21 and the second sorting step 25 are triboelectric sorting steps.

[0069] The fraction 29 containing essentially unfilled polyolefins can then be fed to a color sorting stage 31, in which the polyolefin particles contained in the fraction 29 containing essentially unfilled polyolefins are sorted according to their color. Regardless of whether the color sorting stage 31 is carried out or not, any elastomers 35 present in the fraction 29 containing essentially unfilled polyolefins are separated in an elastomer separation stage 33 and removed from the process. After the elastomers have been separated, the fraction containing essentially unfilled polyolefins is fed to an extruder 37, which preferably has at least one devolatilization zone to remove volatile components 39 or components that decompose into volatile substances from the fraction 29 containing essentially unfilled polyolefins.The melt leaving the extruder 37 is then preferably fed to a melt filtration stage 41, in which any remaining solids 43 are separated from the fraction containing essentially unfilled polyolefins. The melt 45, purified of impurities, can then be fed to a compounding step and processed into semi-finished products, preferably granules, and subsequently used in manufacturing processes for plastic products made from polyolefins.

[0070] The second heavy fraction 17 obtained in the second density separation 13, which contains in particular styrene-based polymers such as HIPS and ABS and optionally filled polyolefins, in particular filled polypropylene, is also preferably dried in a third drying step 47.

[0071] In a third sorting step 49, the second heavy fraction is separated into a styrene-based fraction 51, which contains in particular ABS and PS, a fraction 53 containing HIPS and a fraction 55 containing essentially filled polyolefins.

[0072] The styrene-based fraction 51 is separated in a fourth sorting step 57 into a fraction 59 containing essentially ABS, a fraction 61 containing ABS and HIPS, and a fraction 63 containing filled polyolefins. The fraction containing ABS and HIPS is fed to a fifth sorting step 65, in which the fraction containing ABS and HIPS is separated into a fraction 67 containing essentially ABS and a fraction 69 containing essentially HIPS.

[0073] Due to the generally small amount, the fraction 63 containing filled polyolefins is preferably first collected until a plant-typical throughput of, for example, 1 t / h can be reasonably maintained, before it is fed together with the fraction 55 containing essentially filled polyolefins to a sixth sorting step 71 in which any HIPS still present is separated off, so that a fraction 73 containing HIPS and a fraction 75 containing essentially pure filled polyolefin, in particular talc-filled polypropylene, are obtained.

[0074] The third sorting step 49, the fourth sorting step 57, the fifth sorting step 65, and the sixth sorting step 71 can each independently be at least one triboelectric sorting step, one spectroscopic sorting step, or a combination of triboelectric sorting and spectroscopic sorting. Preferably, the third sorting step 49 and the fourth sorting step 57 are each triboelectric sorting steps, and the fifth sorting step 65 and the sixth sorting step 71 are each spectroscopic sorting steps, for example, sorting based on near-infrared spectroscopy, XRF spectroscopy, or UV spectroscopy. For spectroscopic sorting, a sorter based on NIR spectroscopy is used, particularly for light-colored mixtures, and a sorter based on UV spectroscopy is used for gray or dark mixtures.XRF sorters are particularly suitable for plastics that are separated according to metal content (aluminum, magnesium, silicon).

[0075] For further processing, the essentially ABS-containing fraction 59 and the ABS-containing fraction 67 are fed to a color sorting stage 77. Any elastomers 81 present in the essentially ABS-containing fractions sorted by color can then be separated in an elastomer separation stage 79 and removed from the process. After the elastomers have been separated, the essentially ABS-containing fraction is fed to an extruder 83, which has at least one venting zone for removing volatile components 85 or components that decompose into volatile substances. Solid impurities 89 can then be removed from the ABS melt produced in the extruder 83 in a melt filtration stage 87. The melt 91, purified of impurities, can then be fed to a compounding step and processed into semi-finished products, preferably granules, and subsequently used in processes for producing plastic products from ABS.

[0076] The HIPS-containing fractions 53, 69, 73 separated in the third sorting step 49, fifth sorting step 65, and sixth sorting step 71 are also combined and fed to a color sorting step 93, in which the HIPS-containing fractions are sorted by color. Elastomers 97 can then be separated and removed from the sorted HIPS-containing fractions in an elastomer separation step 95. The HIPS-containing fraction is then melted in an extruder 99, which preferably also has a venting zone in which volatile components 101 and components that decompose into volatile components can be removed. The HIPS-containing melt thus produced is fed to a melt filtration step 103, in which any remaining solid components 105 can be separated.The purified HIPS melt 107 can then be fed into a compounding step and processed into semi-finished products, preferably granules, and subsequently used to manufacture plastic parts from HIPS.

[0077] The filled polyolefin-containing fraction 75 obtained in the sixth sorting step 71 is also preferably fed to a color sorting step 109. Elastomers 113 still contained in the color-sorted fractions obtained there can then be separated in an elastomer separation step 111. The elastomer-free fraction is then melted in an extruder 115, wherein volatile components 117 and components that decompose into volatile substances can be removed in a degassing zone. The melt produced in the extruder 115 can be purified of solid impurities 121 in a melt filtration step 119. The filled polyolefin-containing melt 123 can then be fed to a compounding step and processed into semi-finished products, preferably granules, and subsequently used to produce plastic parts from filled polyolefin, in particular from talc-filled polypropylene.

[0078] In principle, the "principle of intersections" applies to all processing methods. This means that each separation and sorting technology covers a subset that can be found in the basic set. The individual sorting processes are most efficient and have the lowest losses when the sortable subsets overlap. If the subsets do not overlap, the specific sorting process has gaps and a specific subset is not generated and is lost. Ideally, the separation process therefore comprises a sequence of physically different sorting techniques, for example, as described above and in Figure 1 As shown, first a density separation, then a triboelectric sorting, and finally a spectroscopic sorting. However, depending on the composition of the mixture to be separated, any other combination of the three sorting processes may be effective.

[0079] Figure 2shows a second strand of the process according to the invention, in which the first heavy fraction 7 obtained in the first density separation 3 is further processed.

[0080] For this purpose, the first heavy fraction 7 is fed to a classifier 139, in which the plastics contained in the first heavy, metal-free fraction are separated from the circuit board particles also contained therein, which are essentially composed of glass fiber-filled polycarbonate. The separation preferably takes place in an upflow of water or an aqueous medium containing salt, clay, or iron dust. In this process, fraction 7 is introduced against the upflow by forced conveyance so that the particles contained in the first heavy fraction 7 are completely wetted and free of air. This allows the circuit board particles to be efficiently removed from the first heavy fraction 7. The upflow separates them into a coarse fraction 127 and a fine fraction 129. The fine fraction 129 generally corresponds to the web width of the subsequent water tables 131.1, 131.2.Typical bridge widths for water tables are, for example, 10 mm or 20 mm.

[0081] In order to process the coarse fraction 127, it is necessary to reduce the individual particles to a size at which they can be further sorted using the water tables 131.1, 131.2. For this purpose, the coarse fraction is first fed to an air classifier 133, in which inorganic and, in particular, metallic components 134 are removed from the coarse fraction 127, which could damage a subsequent mill 135, in particular the cutting edges of the mill 135. The inorganic and metallic components 134 that could damage the cutting edges of the mill 135 include, in particular, screws, nails, stones, ball bearings, etc. Since these all have a significantly higher density than the plastic parts or circuit board parts to be processed, the separation in the air classifier 133 is sufficiently effective.After separating the parts that could damage the mill, the coarse fraction is introduced into mill 135, and the individual particles of the coarse fraction are comminuted to enable further sorting by means of the downstream water tables 131.1, 131.2. To prevent particles from the coarse fraction that are not yet sufficiently small from being fed to the water tables, mill 135 preferably has a cutting screen through which the sufficiently comminuted particles are removed. The particles that are not yet sufficiently comminuted remain in the grinding process. In this way, the coarse fraction is comminuted in the mill into particles whose size corresponds to the maximum permissible particle size requirement of the downstream processes.

[0082] If the mill has a cutting screen so that only sufficiently comminuted particles leave the mill, the comminuted particles of the coarse fraction that have left the mill are mixed with the fine fraction 129 and freed from their fine fraction 126 in a screen 125. The mesh size of the screen 125 used is preferably 4 mm.

[0083] This produces a fraction 141, which is mostly rich in circuit board particles and cable residues and is fed to the two serially operating water tables 131.1, 131.2, or a fraction 152, which is too poor in metals for processing with the water tables. This distinction, whether it is a fraction 141 or 152, is easily made using a manual or automated XRF analyzer. Using the first water table 131.1, a metal-rich fraction 143 and a fraction 145 containing primarily plastics are separated. The remaining fraction is fed to the second water table 131.2, where a metal-rich fraction 147 and a fraction 149 containing primarily plastics are also separated. In addition to the metal-rich fraction 147 and the fraction 149, which mainly contains plastics, a waste fraction 151 may remain.Both the metal-rich fractions 143 and 147 and the waste fraction 151 generally still contain valuable materials, so they can be subjected to further processing. Waste fraction 151 is preferably analyzed to assess whether it corresponds to the quality of fraction 152. If this is the case, waste fraction 151 is further processed in the same way as fraction 152.

[0084] Fractions 145, 149, and 152, which essentially contain plastics, generally contain a highly complex composition of various plastics, which are particularly relevant for technical applications. For this reason, it is particularly preferred if, as shown here, fractions 145, 149, and 152, which essentially contain plastics, are mixed and further processed.

[0085] For further processing and separation of the fractions 145, 149, 152, which essentially contain plastics, these are fed either separately or, as shown here, mixed with one another, to a third density separation 153. The third density separation 153 is carried out at a density in the range of 1.18 to 1.24 g / cm 3 , more preferably at a density in the range of 1.19 to 1.24 g / cm 3 , further preferably at a density in the range of 1.20 to 1.23 g / cm 3 , and in particular at a density in the range of 1.21 to 1.22 g / cm 3 . Like the first density separation 3 or the second density separation 13, the third density separation 153 can also be carried out in a sink-float system or a cyclone.The third density separation 153 at a density of less than 1.25 g / cm³ prevents polycarbonates or ABS grades with higher glass fiber content from penetrating the essentially pure polymers obtained by the process according to the invention, which would impair the mechanical and optical properties of the corresponding granules. If the density is below 1.22 g / cm³, carryover of polyoxymethylene can also be prevented, which would make further processing of the polymers with an extruder or injection molding machine impossible due to health-endangering limit value violations.

[0086] In the third density separation 153, the fractions 145, 149, which essentially contain plastics, as well as the fraction 152 containing the plastics, are separated into a third light fraction 155 and a third heavy fraction 157. The third light fraction 155 contains polyamides, polycarbonates, and methacrylate-based polymers, and the third heavy fraction 157 contains polyoxymethylene, highly filled polymers, and halogen-containing polymers. The halogen-containing polymers include, in particular, polyvinyl chloride (PVC) and plastics with brominated flame retardants. The highly filled polymers contain, for example, fibers, especially glass fibers or chalk.

[0087] The third light fraction 155 obtained in the third density separation 153 is fed to an XRF spectroscopic separation 154 for further separation into essentially pure polymers, producing a fraction 264 containing essentially highly filled polyolefins and a fraction 158 containing polyamides, polycarbonates, and methacrylate-based polymers. The fraction 264 containing essentially highly filled polyolefins contains, for example, polyolefins filled with 10 to 50% talc.

[0088] The fraction 264, which essentially contains highly filled polyolefins, is preferably fed to a color sorter 265, as already described above for the polyolefins, the styrene-based polymers, and the fractions containing filled polyolefins. From the fractions sorted by color there, any PUR elastomers 268 still present can then be separated from the fraction essentially containing polycarbonates in an elastomer separation 266. The fraction 267, freed from PUR elastomers, is then melted in an extruder 269, wherein volatile components 271 and components that decompose into volatile substances can be removed in a vent zone. The melt 270 produced in the extruder 269 can be purified of solid impurities 274 in a melt filtration 272.Subsequently, the talc-containing melt 273 is also preferably processed into semi-finished products, such as granules, which can then be used in processes for producing plastic parts from polypropylene filled with talc and / or chalk.

[0089] The fraction 158 containing polyamides, polycarbonates, and methacrylate-based polymers is fed to a spectroscopic sorting step 159, in which essentially polycarbonates 161 are separated. The spectroscopic sorting step 159 is preferably carried out in the color-independent UV spectrum. In order to be able to separate heavy components, particularly POM-containing particles, with the aid of air blasts during the spectroscopic sorting step 159, it is further preferred that the particles to be sorted have a grain size of less than 20 mm.

[0090] The fraction 161 containing essentially polycarbonates is preferably fed to a color sorter 173, as already described above for the polyolefins, the styrene-based polymers, and the fractions containing filled polyolefins. From the fractions sorted by color there, any elastomers 177 still present can then be separated from the fraction containing essentially polycarbonates in an elastomer separation 175. The fraction freed from elastomers is then melted in an extruder 179, wherein volatile components 181 and components that decompose into volatile substances can be removed in a venting zone. The melt produced in the extruder 179 can be purified of solid impurities 185 in a melt filtration 183.Subsequently, melt 187, which essentially contains polycarbonates, is also preferably processed into semi-finished products, such as granules, which can then be used in processes for producing plastic parts from polycarbonate.

[0091] In the spectroscopic sorting 159, in addition to the fraction 161 containing essentially polycarbonates, a fraction 163 containing essentially polyamides and methacrylate-based polymers, for example, polymethyl methacrylate (PMMA), is produced. The fraction 163 containing essentially polyamides and methacrylate-based polymers is fed to a further spectroscopic sorting 165, in which a fraction 167 containing methacrylate-based polymers is separated. The remaining fraction contains, in particular, polymers and foreign plastics. This remaining fraction is also fed to a spectroscopic sorting 169, in which a polyamide-containing fraction 171 and a residual fraction 172 are obtained. The residual fraction 172 cannot generally be recycled economically and is therefore preferably fed to thermal recycling.

[0092] For further processing, the fraction containing essentially methacrylate-based polymers is fed to a color sorter 189, where it is sorted, in particular, for transparency. The sorted fractions can then be fed to an elastomer separation 191 to remove any remaining elastomers 193. The fraction freed from elastomers can then be melted in an extruder 195, wherein the extruder 195 preferably also has a degassing zone in which volatile components 197 or components that decompose into volatile substances can be removed. Solid impurities 201 can be removed with the aid of a melt filtration 199, and the thus purified melt 203 can be processed into semi-finished products, for example, granules, which can be used to manufacture plastic parts from methacrylate-based polymers, in particular from polymethyl methacrylate.

[0093] The fraction containing essentially polyamides is also preferably fed to a color sorting stage 205, and the fractions sorted by color are then fed to an elastomer separation stage 207 to remove any remaining elastomers 209. The fraction freed from elastomers is melted in an extruder 211, wherein volatile components 213 or components that decompose into volatile substances are preferably removed in the extruder. The melt produced in the extruder 211 can then also be purified of solid components 217 in a melt filtration stage 215, so that a melt 219 containing essentially polyamides is obtained, which can be processed into a corresponding granulate. However, it should be noted that a mixture of very different polyamides is usually obtained, and these are not present in pure form.In the case of a mixture of incompatible polyamides, these cannot be mechanically separated according to the current state of the art. In this case, such a mixture can be subjected to chemical recycling. Compatibility can also be achieved in the 211 extruder.

[0094] The third heavy fraction 157, which essentially contains polyoxymethylene, highly filled polymers, and halogen-containing polymers, is fed to a spectroscopic sorting stage 221, in which a fraction 223 containing essentially chlorine-containing polymers, in particular PVC, is separated from the third heavy fraction 157. The spectroscopic sorting stage 221 is preferably carried out using UV spectroscopy or XRF spectroscopy. The resulting fraction 223, which essentially contains chlorine-containing polymers, in particular PVC, can be fed to a color sorting stage 225 for further processing or, alternatively or additionally, to a sorting stage based on elasticity.

[0095] In a subsequent elastomer separation 227, elastomers 229 can be separated. Alternatively, it is also possible to use a rubber separator used for elastomer separation 227 to separate the fraction containing essentially chlorine-containing polymers, in particular PVC, into soft PVC and rigid PVC. The fractions containing chlorine-containing polymers, in particular PVC, freed from elastomers 229 are preferably melted in an extruder 231 with at least one venting zone for removing volatile components 233 or components that decompose into volatile substances. The melt 239 can then be purified of solid impurities 237 in a melt filtration 235 and subsequently formed into granules or other semi-finished products.

[0096] The fraction 241 remaining after the separation of the chlorine-containing polymers in the spectroscopic sorting stage 221 contains particularly high concentrations of bromine and antimony. The concentration of bromine and antimony is generally so high that this remaining fraction 241 is a more economical source of bromine and antimony than natural deposits.

[0097] For further processing, the remaining fraction 241 is fed to a spectroscopic sorting 243, in which highly filled composites, in particular highly filled glass fiber composites, polyoxymethylenes such as POM-h and POM-c and their alloys, polybutylene terephthalate, polyphenylene sulfide and other polymers are separated as reject fraction 245 in order to further increase the contents of bromine and antimony.

[0098] For this purpose, the material is preferably sorted for bromine in a first step using UV or XRF spectra, usually producing a bromine-rich ABS / HIPS mixture, which is then electrostatically separated into a bromine-rich ABS fraction and a bromine-rich HIPS fraction. This separation into ABS and HIPS enables the recycling of the plastic components during subsequent processing.

[0099] The reject fraction 245 can be further separated into its individual components using suitable density cuts and sorting processes. This allows for the recovery of POM, PBT, and the group of polysulfones and polysulfides, in particular. To achieve purities of greater than 99% for these engineering plastics, a corresponding plant size of at least 200,000 tons of annual processing capacity is currently required for an economical process.

[0100] From the bromine-containing fraction 244 obtained in the spectroscopic sorting 243, elastomers 249 can be separated in a subsequent elastomer separation 247. Subsequently, in a processing step 251, the brominated flame retardants are dissolved from the bromine-containing fractions, in particular the brominated ABS fraction and the brominated HIPS fraction, using suitable solvents. The preceding separation into ABS and HIPS allows a largely bromine-free polymer matrix to be obtained for subsequent extrusion. The polymers thus obtained, freed from brominated flame retardants, are freed from solid impurities 255 in a melt filtration 253, and the solvents used to remove the brominated flame retardants are subsequently separated in a solvent recovery 257. The solvents 259 separated in this way can be used again to separate the brominated flame retardants.In addition to the solvents, waste materials 261 are preferably also separated in the solvent recovery 257, so that granules or semi-finished products 263 are obtained which are essentially solvent-free, free from brominated flame retardants and free from other undesirable impurities and in particular essentially contain ABS or HIPS.

[0101] Regardless of the polymers used, additives necessary for polymer reuse can be added to each of the extrusions described above, bringing these sometimes outdated plastic types up to the standard of today's applications. These can include, for example, antioxidants, impact modifiers, chain extenders, chain reducers, UV stabilizers, internal or external lubricants, alloy partners, or even virgin materials.

[0102] Figure 3 shows an alternative embodiment of the pre-sorting for the processing of the first heavy fraction 7.

[0103] In contrast to the Figure 2 The pre-sorting shown in Figure 3 In the pre-sorting shown, the first heavy fraction 7 is first separated into a coarse fraction 127 and a fine fraction 129 using the oversize screen 275. The mesh size of the oversize screen 275 depends on the web width of the subsequent water tables 131.1, 131.2 and preferably corresponds to the web width of the water tables.

[0104] In order to also process the coarse fraction 127 removed from the oversize screen 125, it is necessary to reduce the individual particles to a size that allows them to be further sorted using the water tables 131.1, 131.2. For this purpose, the coarse fraction 127 is first fed to an air classifier 133, in which the inorganic, particularly metallic, components 134 that could damage a downstream mill 135, particularly the cutting edges of the mill 135, are removed from the coarse fraction 127. After separating the inorganic, particularly metallic, components that could damage the mill, the coarse fraction is introduced into the mill 135, and the individual particles of the coarse fraction are reduced in size so that further sorting using the downstream water tables 131.1, 131.2 is possible.To prevent particles from the coarse fraction that are not yet sufficiently small from being fed to the water tables, it is advantageous to first sieve the coarse fraction leaving the mill and then re-feed the particles that remain in the sieve as oversize to the mill 135. Alternatively, it is also possible to return the fraction leaving the mill to the oversize sieve 125, so that the sufficiently comminuted particles are removed as the fine fraction 129, and the oversized particles are re-fed to the mill 135 as oversize via the air classifier 123.

[0105] Alternatively and preferably, however, the mill 135 comprises a cutting screen through which the sufficiently comminuted particles are removed. The particles that are not yet sufficiently comminuted are fed back into the grinding process. In this way, the coarse fraction is comminuted in the mill into particles whose size corresponds to the size of the particles in the fine fraction.

[0106] If the mill has a cutting screen so that only the sufficiently crushed particles leave the mill, the crushed particles of the coarse fraction that have left the mill and the fine fraction 127 are mixed together again to form a first heavy, metal-free fraction 137.

[0107] When the fraction leaving the mill 135 is fed again to the oversize screen 275, the mixing of the first light fraction 129 and the crushed coarse fraction 127 already takes place on the oversize screen 275, so that in this case the fine fraction 129 is already the first heavy, metal-free fraction.

[0108] The first heavy, metal-free fraction 137 is fed to a classifier 139, in which the plastics contained in the first heavy, metal-free fraction are separated from the circuit board particles also contained therein, which are essentially composed of glass fiber-filled polycarbonate. The separation preferably takes place in an upflow of water or an aqueous medium containing salt, clay, or iron dust. In this process, the first heavy, metal-free fraction 137 is introduced by forced conveyance against the upflow, so that the particles contained in the first heavy, metal-free fraction are completely wetted and free of air. This allows the circuit board particles to be efficiently removed from the first heavy, metal-free fraction. In this way, a circuit board particle-rich fraction 141 is produced in the classifier 139, which is fed to the two serially operating water tables 131.1, 131.2.The first water table 131.1 separates a metal-rich fraction 143 and a fraction 145 containing primarily plastics. The remaining fraction is fed to the second water table 131.2, where a metal-rich fraction 147 and a fraction 149 containing primarily plastics are also separated. In addition to the metal-rich fraction 147 and the fraction 149 containing primarily plastics, a waste fraction 151 remains. Both the metal-rich fractions 143 and 147, as well as the waste fraction 151, generally still contain valuable materials, so they can be subjected to further processing.

[0109] The fractions 145, 149, which essentially contain plastics, generally contain a highly complex composition of various plastics, which are particularly relevant for technical applications. For this reason, it is particularly preferred if, as shown here, the fractions 145, 149, which essentially contain plastics, are mixed with the fraction 152, which contains plastics and is separated in the classifier 139, and then further processed.

[0110] Further processing is then preferably carried out as described above for Figure 2 described.

Claims

1. Method for recovering plastics from a mixture of at least two polymers, wherein one polymer is contained with a share of 1% to 99% by weight, comprising: (a) carrying out a first density separation (3) at a density in the range from 1.14 to 1.18 g / cm3, to give a first light fraction (5), which contains polyolefins and styrene-based polymers, and a first heavy fraction (7); (b) supplying the first light fraction to a second density separation (13) at a density in the range from 1.00 to 1.03 g / cm3, to give a second light fraction (15), which contains unfilled polyolefins, and a second heavy fraction (17), which contains styrene-based polymers and possibly filled polyolefins; (c) supplying the first heavy fraction (7) to a third density separation (153) at a density in the range from 1.18 to 1.24 g / cm3, wherein the first heavy fraction (7) is separated into a third light fraction (155), which contains polyamides, polycarbonates and methacrylate-based polymers, and a third heavy fraction (157) containing polyoxymethylene, highly filled polymers and halogen-containing polymers; (d) separating all the fractions into fractions substantially containing single-grade polymers, wherein, before the third density separation (153), metal-containing components (143, 147) are removed from the first heavy fraction (7).

2. Method according to Claim 1, characterized in that the second heavy fraction (17) is separated into • a fraction (51) substantially containing styrene-based polymers and • a fraction (55) substantially containing filled polyolefins.

3. Method according to Claim 2, characterized in that the separation of the second heavy fraction (17) is carried out in at least one triboelectric sorting, at least one spectroscopic sorting or a combination of triboelectric and spectroscopic sorting.

4. Method according to any of Claims 1 to 3, characterized in that lightweight substances (27) and waste substances (23) are separated off from the second light fraction (15) to give a fraction (29) substantially containing unfilled polyolefins.

5. Method according to Claim 4, characterized in that the separation of the lightweight substances (27) and waste substances (23) from the second light fraction (15) is carried out in at least one triboelectric sorting, at least one spectroscopic sorting or combinations of triboelectric and spectroscopic sorting.

6. Method according to any of Claims 1 to 5, characterized in that the first heavy fraction (7), for the removal of the metal-containing components (143, 147), (i) is separated into a coarse fraction (127) and a fine fraction (129), (ii) any inorganic and metallic constituents (134) are removed from the coarse fraction (127), (iii) the coarse fraction (127) is comminuted, (iv) the fine fraction (129) and the coarse fraction (127) are subsequently mixed again with one another to give a first heavy, metal-free fraction (137), and (v) the metal-free fraction (137) is freed from the fines.

7. Method according to any of Claims 1 to 6, characterized in that the third light fraction (155) is separated into • a fraction (264) substantially containing highly filled polyolefins, • a fraction (171) substantially containing polyamides, • a fraction (161) substantially containing polycarbonate, and • a fraction (167) substantially containing methacrylate-based polymers.

8. Method according to Claim 7, characterized in that the separation of the third light fraction (155) is carried out in at least one X-ray reflection-spectroscopic or at least one triboelectric sorting, at least one spectroscopic sorting or combinations of triboelectric and spectroscopic sorting.

9. Method according to any of Claims 1 to 8, characterized in that the third heavy fraction (157) containing polyoxymethylene, highly filled polymers and halogen-containing polymers is separated into • a fraction containing polyoxymethylene, • a fraction containing filled polymers, • a bromine-containing fraction (244), and • a fraction (223) substantially containing chlorine-containing polymers.

10. Method according to Claim 9, characterized in that the separations of the third heavy fraction (157) containing polyoxymethylene, highly filled polymers and halogen-containing polymers into the fraction containing polyoxymethylene, the fraction containing filled polymers, the bromine-containing fraction (244) and the fraction (223) substantially containing chlorine-containing polymers are carried out in respectively at least one triboelectric sorting, at least one spectroscopic sorting, or combinations of triboelectric and spectroscopic sorting, wherein the halogen-containing, more particularly bromine- or chlorine-containing, polymers are accumulated with at least one X-ray reflection-spectroscopic sorting.

11. Method according to any of Claims 1 to 10, characterized in that elastomers are separated off from the fractions (29, 53, 59, 75, 161, 167, 171, 223, 244) substantially containing single-grade polymers.

12. Method according to any of Claims 1 to 11, characterized in that the fractions (29, 53, 59, 75, 161, 167, 171, 223, 244) substantially containing single-grade polymers are extruded to give pellets.

13. Method according to Claim 12, characterized in that components (39, 85, 101, 117, 181, 197, 213, 233) which are volatile in the extrusion at subatmospheric pressure or components which decompose to give volatile components are separated off by one or more vacuum degassings and / or solid or elastic components (43, 89, 105, 121, 185, 201, 217, 237, 255) are separated off by one or more melt filtrations (41, 87, 103, 119, 183, 199, 215, 235, 253).