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Polymer type composition of monitor and TV components and mixed SHA. ABS: acrylonitrile butadiene styrene; PC/ABS: polycarbonate/acrylo- nitrile butadiene styrene; PS: polystyrene.
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Waste electrical and electronic equipment is a complex waste stream and treatment options that work for one waste category or product may not be appropriate for others. A comprehensive case study has been performed for plastic-rich fractions that are treated in German dismantling centres. Plastics from TVs, monitors and printers and small household...
Contexts in source publication
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... spectroscopic polymer-type identification was used to get an idea of the polymer-type composition of monitor and TV components and mixed SHA. Figure 2 depicts the results. Figure 2 reveals a high ABS-PC and ABS content for all monitor components. ...
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... spectroscopic polymer-type identification was used to get an idea of the polymer-type composition of monitor and TV components and mixed SHA. Figure 2 depicts the results. Figure 2 reveals a high ABS-PC and ABS content for all monitor components. PS was mainly used for M feet . ...
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... results of the 100 unsorted TV samples shown in Figure 2 reveal that 86 specimens were composed of HIPS, nine of ABS and five of other polymer types. The XRF identified bromine contents above 0.1% in 36% of the HIPS samples. ...
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... higher process yield could be achieved if only TV fronts were used, but since TV backs make up a bigger fraction of the WEEE stream, treating all TV components is recommended. Figure 2 depicts a rather high variety of materials in a mixed batch of SHA. Contents between 16% and 22% were identified for ABS, PS and polyolefins. ...
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... were performed for the output fractions of the crushing process to determine the particle size distribution. To characterise the big batches of M&P casings, TV casings and SHA static density fractionation was performed on a laboratory scale with samples from the coarse particle size reduction. Dipotassium phosphate was dissolved in water to create a density media of 1.0 g cm -3 , 1.03 g cm -3 , 1.06 g cm -3 , 1.07 g cm -3 , 1.08 g cm -3 and 1.09 g cm -3 . In the first step, the lightest density fraction was separated from 10 kg of each batch, the material was dried and the mass balances were recorded. The bromine content of the light fraction was measured by XRF. The heavy fraction of this first step was then introduced to the density medium of 1.03 g cm -3 , the material was dried, mass balances were recorded and the bromine content of the lighter fraction was measured. This procedure was repeated with media of higher densities until the bromine value exceeded 0.1% to determine which density cuts are expedient on a technical scale to produce legally marketable recyclates with high process yields. To determine tensile and impact strength of recycled styrenics and polyolefins, test specimen were produced. The recyclates were homogenised and cleaned in a single-screw extruder with a screen of 150 μm. The extrusion temperatures varied between 180 °C and 230 °C and pressures up to 200 bar were applied. The extruded products were granulated and test specimen were produced by injection moulding at 240 °C for ABS, polystyrene (PS) and ABS-PC, and 190 °C for PP. The injection moulding dies had temperatures between 45 °C and 60 °C. Tensile and impact (Charpy method) tests were performed in accordance to standardised methods (DIN EN ISO 3167, DIN EN ISO 179). Dismantling of TVs, monitors, printers and vacuum cleaners was performed manually to remove the panel glass, cartridges and motors in German dismantling centres. Coffee dispensers and vacuum cleaners were separated by hand sorting from batches of SHA. One dismantler applied sliding spark spectroscopy to identify halogens in casings of TVs and M&P, and to separate halogenated parts from halogen-free ones. For material sorting, manual dismantling, hand-sorting, handheld spectroscopic devices, crushing, automated NIR or continuous density separation and combinations of these techniques were applied. Figure 1 depicts the treatment scheme for the different input streams. Two basic approaches were chosen for material sorting. M&P casings were sorted by NIR separation and the particle size of the sorted ABS and PS fractions was further reduced to separate halogenated parts by density separation. The NIR-based separation approach was also tested for SHA casings, but was not pursued owing to insufficient process efficiency. Because of the high content of dark parts, TV casings, mixed SHA fractions, SHA coffee and SHA vacuum were directly introduced to the density separation process. The separated casings were pressed and shipped to a business partner who crushed the material in a rotary shear and granulator (both Andritz-MEWA GmbH, Gechingen, Germany). Fine grains were separated by a zigzag air-classifier (AUT GmbH, Chemnitz, Germany). Iron was extracted by an overhead suspension magnet and a neodymium magnet (both Steinert Elektromagnetebau, Cologne, Germany), and non-ferrous metals were removed by an eddy current separa- tor. Batches for the downstream continuous density separation were introduced to a hammer mill (Herbold, Meckesheim, Germany) for crushing to particle sizes below 8 mm. Automated NIR separation was tested on a technical scale with a UNISORT® NIR separation system (RTT-Steinert GmbH, Zittau, Germany). The first sorting step was performed with a multiplex sensor. The remaining fraction of parts that could not be identified was sorted once more by applying a camera system with an increased sensor resolution. Technical scale NIR separation was performed for M&P casings and for a batch of mixed SHA. On a technical scale, continuous density separation was performed with the Sorticanter ® (Flottweg, Vilsbiburg, Germany). The density media were produced by dissolving dipotassium phosphate in water to produce a density media of 1.0 g cm -3 , 1.06 g cm -3 and 1.08 g cm -3 . Which density cuts were chosen for which fraction was decided according to the results of the material characterisation. An input of 100 kg was the minimum amount for the Sorticanter ® to obtain separation results with repetitious accuracy. Continuous density separation was applied to sort halogen-free PS fractions from TV casings and halogen-free ABS and PS fractions of NIR pre-sorted M&P casings. From a batch of mixed SHA and from the sub-fractions SHA coffee and SHA vacuum , polyolefins and halogen-free styrenics were separated. Handheld spectroscopic polymer-type identification was used to get an idea of the polymer-type composition of monitor and TV components and mixed SHA. Figure 2 depicts the results. Figure 2 reveals a high ABS-PC and ABS content for all monitor components. PS was mainly used for M feet . In addition to the polymer type identification, M feet , M fronts and M backs of 908 monitor casings were characterised by handheld sliding spark spectroscopy to identify the presence of halogens. A total of 29% of M fronts contained chlorine and/or bromine and 28% of M backs , respectively. Less halogens were found in M feet , only 10% of the parts contained bromine and/or chlorine. The XRF results of the scrap material correlate with these results. For M backs , a total bromine content of 2.4% was measured and 0.15% for the feet. The results of the 100 unsorted TV samples shown in Figure 2 reveal that 86 specimens were composed of HIPS, nine of ABS and five of other polymer types. The XRF identified bromine contents above 0.1% in 36% of the HIPS samples. The chlorine content exceeded 0.5%, even though the bromine level was below 0.1% for another 8% of the HIPS samples. A cadmium content of 0.01% was exceeded for 19% of the samples, but only if either the bromine or chlorine content was too high as well. The bromine content of all ABS samples exceeds 0.1% and the legal threshold for cadmium is exceeded for most ABS samples. Manufacturers could be assigned to all TV parts analysed and ABS was almost exclusively used by a certain manufacturer. From these results, a halogen-free HIPS target fraction of 50% of the total TV fraction could be expected. Since no other halogen- free styrenics could be found, density separation appears to be a promising treatment to produce a pure halogen-free HIPS recy- clate. The polymer type composition of TV fronts and TV backs is similar. Comparing the XRF results of TV backs and TV fronts reveals that 37% of the backs exceeded bromine levels of 0.1% and only 6% of the fronts exceeded this value. A higher process yield could be achieved if only TV fronts were used, but since TV backs make up a bigger fraction of the WEEE stream, treating all TV components is recommended. Figure 2 depicts a rather high variety of materials in a mixed batch of SHA. Contents between 16% and 22% were identified for ABS, PS and polyolefins. Polyamide and polycarbonate could also be identified and a content of 33% of other plastics, metals and other material. The results of the static laboratory density fractionation are illustrated by Figure 3. For M&P casings, the bromine content stays below 0.1% for material densities of 1.08 g cm -3 and below, but the yield is only approximately 22% for both batches analysed. For the two batches of unsorted TV casings, legal thresholds for bromine can be kept when a density cut of 1.06 g cm -3 is applied. At this density cut, the yield is 69% and 77%. While the density fractions of both dismantlers show similar compositions for TV casings as well as for M&P casings, the two batches of SHA differ remarkably. For SHA 1 the bromine content stays below 0.1%, even in higher density fractions. Anyhow, thresholds for lead and cadmium are exceeded in this batch. The bromine content of batch SHA 2 exceeds 0.2% in the density fraction 1.07 g cm -3 < ρ < 1.08 g cm -3 . The cumulative yields of these two batches differ remarkably as the polyolefin content of SHA 1 is approximately 15% higher than that of SHA 2. Workers of the cooperating dismantling centres observed high variations of the input composition, dependent on time and delivering client. After the first coarse size reduction process, 85% to 90% of the parts are in the size range between 12 mm and 45 mm. Between 6% and 8% of the parts are smaller than 12 mm and 4% to 7% are larger than 45 mm. This particle size distribution was determined for casings of M&P, TVs and SHA. For the applied NIR separation process, particle sizes above 12 mm were necessary to achieve the best separation results relating to yield and purity. Figure 4 shows the NIR separation results for casings of M&P and SHA. Separation yield and impurities of each target fraction are depicted. TVs were mostly black and therefore not sorted by NIR separation. The achieved purities of the sorted target fractions vary between 68% and 90% for ABS, 51% and 77% for PS, and 79% and 94% for PC/ABS.] For M&P casings, 19% to 31% remained unsortable after a two-step NIR sortation. The predominant share of unsortable parts was smaller than 20 mm. The results for the M&P-X fraction in which halogenated parts were enriched, reveal a high content of ABS and only little PS and ABS-PC compared with the other M&P fractions sorted. Non-styrenic impurities of the ABS and HIPS target fraction are expected to be removed in the downstream density separation. The fraction of M&P casings contained mainly grey plastics and was thus an adequate input for the NIR-based separation. Two separation steps were necessary to achieve good yields for better product qualities. An optimised crushing, singularisation and calibration could ...
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... to the density medium of 1.03 g cm -3 , the material was dried, mass balances were recorded and the bromine content of the lighter fraction was measured. This procedure was repeated with media of higher densities until the bromine value exceeded 0.1% to determine which density cuts are expedient on a technical scale to produce legally marketable recyclates with high process yields. To determine tensile and impact strength of recycled styrenics and polyolefins, test specimen were produced. The recyclates were homogenised and cleaned in a single-screw extruder with a screen of 150 μm. The extrusion temperatures varied between 180 °C and 230 °C and pressures up to 200 bar were applied. The extruded products were granulated and test specimen were produced by injection moulding at 240 °C for ABS, polystyrene (PS) and ABS-PC, and 190 °C for PP. The injection moulding dies had temperatures between 45 °C and 60 °C. Tensile and impact (Charpy method) tests were performed in accordance to standardised methods (DIN EN ISO 3167, DIN EN ISO 179). Dismantling of TVs, monitors, printers and vacuum cleaners was performed manually to remove the panel glass, cartridges and motors in German dismantling centres. Coffee dispensers and vacuum cleaners were separated by hand sorting from batches of SHA. One dismantler applied sliding spark spectroscopy to identify halogens in casings of TVs and M&P, and to separate halogenated parts from halogen-free ones. For material sorting, manual dismantling, hand-sorting, handheld spectroscopic devices, crushing, automated NIR or continuous density separation and combinations of these techniques were applied. Figure 1 depicts the treatment scheme for the different input streams. Two basic approaches were chosen for material sorting. M&P casings were sorted by NIR separation and the particle size of the sorted ABS and PS fractions was further reduced to separate halogenated parts by density separation. The NIR-based separation approach was also tested for SHA casings, but was not pursued owing to insufficient process efficiency. Because of the high content of dark parts, TV casings, mixed SHA fractions, SHA coffee and SHA vacuum were directly introduced to the density separation process. The separated casings were pressed and shipped to a business partner who crushed the material in a rotary shear and granulator (both Andritz-MEWA GmbH, Gechingen, Germany). Fine grains were separated by a zigzag air-classifier (AUT GmbH, Chemnitz, Germany). Iron was extracted by an overhead suspension magnet and a neodymium magnet (both Steinert Elektromagnetebau, Cologne, Germany), and non-ferrous metals were removed by an eddy current separa- tor. Batches for the downstream continuous density separation were introduced to a hammer mill (Herbold, Meckesheim, Germany) for crushing to particle sizes below 8 mm. Automated NIR separation was tested on a technical scale with a UNISORT® NIR separation system (RTT-Steinert GmbH, Zittau, Germany). The first sorting step was performed with a multiplex sensor. The remaining fraction of parts that could not be identified was sorted once more by applying a camera system with an increased sensor resolution. Technical scale NIR separation was performed for M&P casings and for a batch of mixed SHA. On a technical scale, continuous density separation was performed with the Sorticanter ® (Flottweg, Vilsbiburg, Germany). The density media were produced by dissolving dipotassium phosphate in water to produce a density media of 1.0 g cm -3 , 1.06 g cm -3 and 1.08 g cm -3 . Which density cuts were chosen for which fraction was decided according to the results of the material characterisation. An input of 100 kg was the minimum amount for the Sorticanter ® to obtain separation results with repetitious accuracy. Continuous density separation was applied to sort halogen-free PS fractions from TV casings and halogen-free ABS and PS fractions of NIR pre-sorted M&P casings. From a batch of mixed SHA and from the sub-fractions SHA coffee and SHA vacuum , polyolefins and halogen-free styrenics were separated. Handheld spectroscopic polymer-type identification was used to get an idea of the polymer-type composition of monitor and TV components and mixed SHA. Figure 2 depicts the results. Figure 2 reveals a high ABS-PC and ABS content for all monitor components. PS was mainly used for M feet . In addition to the polymer type identification, M feet , M fronts and M backs of 908 monitor casings were characterised by handheld sliding spark spectroscopy to identify the presence of halogens. A total of 29% of M fronts contained chlorine and/or bromine and 28% of M backs , respectively. Less halogens were found in M feet , only 10% of the parts contained bromine and/or chlorine. The XRF results of the scrap material correlate with these results. For M backs , a total bromine content of 2.4% was measured and 0.15% for the feet. The results of the 100 unsorted TV samples shown in Figure 2 reveal that 86 specimens were composed of HIPS, nine of ABS and five of other polymer types. The XRF identified bromine contents above 0.1% in 36% of the HIPS samples. The chlorine content exceeded 0.5%, even though the bromine level was below 0.1% for another 8% of the HIPS samples. A cadmium content of 0.01% was exceeded for 19% of the samples, but only if either the bromine or chlorine content was too high as well. The bromine content of all ABS samples exceeds 0.1% and the legal threshold for cadmium is exceeded for most ABS samples. Manufacturers could be assigned to all TV parts analysed and ABS was almost exclusively used by a certain manufacturer. From these results, a halogen-free HIPS target fraction of 50% of the total TV fraction could be expected. Since no other halogen- free styrenics could be found, density separation appears to be a promising treatment to produce a pure halogen-free HIPS recy- clate. The polymer type composition of TV fronts and TV backs is similar. Comparing the XRF results of TV backs and TV fronts reveals that 37% of the backs exceeded bromine levels of 0.1% and only 6% of the fronts exceeded this value. A higher process yield could be achieved if only TV fronts were used, but since TV backs make up a bigger fraction of the WEEE stream, treating all TV components is recommended. Figure 2 depicts a rather high variety of materials in a mixed batch of SHA. Contents between 16% and 22% were identified for ABS, PS and polyolefins. Polyamide and polycarbonate could also be identified and a content of 33% of other plastics, metals and other material. The results of the static laboratory density fractionation are illustrated by Figure 3. For M&P casings, the bromine content stays below 0.1% for material densities of 1.08 g cm -3 and below, but the yield is only approximately 22% for both batches analysed. For the two batches of unsorted TV casings, legal thresholds for bromine can be kept when a density cut of 1.06 g cm -3 is applied. At this density cut, the yield is 69% and 77%. While the density fractions of both dismantlers show similar compositions for TV casings as well as for M&P casings, the two batches of SHA differ remarkably. For SHA 1 the bromine content stays below 0.1%, even in higher density fractions. Anyhow, thresholds for lead and cadmium are exceeded in this batch. The bromine content of batch SHA 2 exceeds 0.2% in the density fraction 1.07 g cm -3 < ρ < 1.08 g cm -3 . The cumulative yields of these two batches differ remarkably as the polyolefin content of SHA 1 is approximately 15% higher than that of SHA 2. Workers of the cooperating dismantling centres observed high variations of the input composition, dependent on time and delivering client. After the first coarse size reduction process, 85% to 90% of the parts are in the size range between 12 mm and 45 mm. Between 6% and 8% of the parts are smaller than 12 mm and 4% to 7% are larger than 45 mm. This particle size distribution was determined for casings of M&P, TVs and SHA. For the applied NIR separation process, particle sizes above 12 mm were necessary to achieve the best separation results relating to yield and purity. Figure 4 shows the NIR separation results for casings of M&P and SHA. Separation yield and impurities of each target fraction are depicted. TVs were mostly black and therefore not sorted by NIR separation. The achieved purities of the sorted target fractions vary between 68% and 90% for ABS, 51% and 77% for PS, and 79% and 94% for PC/ABS.] For M&P casings, 19% to 31% remained unsortable after a two-step NIR sortation. The predominant share of unsortable parts was smaller than 20 mm. The results for the M&P-X fraction in which halogenated parts were enriched, reveal a high content of ABS and only little PS and ABS-PC compared with the other M&P fractions sorted. Non-styrenic impurities of the ABS and HIPS target fraction are expected to be removed in the downstream density separation. The fraction of M&P casings contained mainly grey plastics and was thus an adequate input for the NIR-based separation. Two separation steps were necessary to achieve good yields for better product qualities. An optimised crushing, singularisation and calibration could further improve yield and purity. The unsortable rest of SHA casings amounts to 74% and was dominated by dark plastics. This observation and the results from the material characterisation lead to the decision to drop this approach. In the proceedings, the focus was put on density separation for SHA unsorted and the subfractions SHA coffee and SHA vacuum that two of the dismantling centres separate routinely from the entire batch of SHA. NIR-sorted ABS and HIPS from M&P casings were introduced to the continuous density separation process. According to the laboratory results, a density cut of 1.08 g cm -3 was applied to separate halogenated particles from M&P fractions. For TV casings and SHA fractions, a density cut of ...
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... spectroscopy to identify halogens in casings of TVs and M&P, and to separate halogenated parts from halogen-free ones. For material sorting, manual dismantling, hand-sorting, handheld spectroscopic devices, crushing, automated NIR or continuous density separation and combinations of these techniques were applied. Figure 1 depicts the treatment scheme for the different input streams. Two basic approaches were chosen for material sorting. M&P casings were sorted by NIR separation and the particle size of the sorted ABS and PS fractions was further reduced to separate halogenated parts by density separation. The NIR-based separation approach was also tested for SHA casings, but was not pursued owing to insufficient process efficiency. Because of the high content of dark parts, TV casings, mixed SHA fractions, SHA coffee and SHA vacuum were directly introduced to the density separation process. The separated casings were pressed and shipped to a business partner who crushed the material in a rotary shear and granulator (both Andritz-MEWA GmbH, Gechingen, Germany). Fine grains were separated by a zigzag air-classifier (AUT GmbH, Chemnitz, Germany). Iron was extracted by an overhead suspension magnet and a neodymium magnet (both Steinert Elektromagnetebau, Cologne, Germany), and non-ferrous metals were removed by an eddy current separa- tor. Batches for the downstream continuous density separation were introduced to a hammer mill (Herbold, Meckesheim, Germany) for crushing to particle sizes below 8 mm. Automated NIR separation was tested on a technical scale with a UNISORT® NIR separation system (RTT-Steinert GmbH, Zittau, Germany). The first sorting step was performed with a multiplex sensor. The remaining fraction of parts that could not be identified was sorted once more by applying a camera system with an increased sensor resolution. Technical scale NIR separation was performed for M&P casings and for a batch of mixed SHA. On a technical scale, continuous density separation was performed with the Sorticanter ® (Flottweg, Vilsbiburg, Germany). The density media were produced by dissolving dipotassium phosphate in water to produce a density media of 1.0 g cm -3 , 1.06 g cm -3 and 1.08 g cm -3 . Which density cuts were chosen for which fraction was decided according to the results of the material characterisation. An input of 100 kg was the minimum amount for the Sorticanter ® to obtain separation results with repetitious accuracy. Continuous density separation was applied to sort halogen-free PS fractions from TV casings and halogen-free ABS and PS fractions of NIR pre-sorted M&P casings. From a batch of mixed SHA and from the sub-fractions SHA coffee and SHA vacuum , polyolefins and halogen-free styrenics were separated. Handheld spectroscopic polymer-type identification was used to get an idea of the polymer-type composition of monitor and TV components and mixed SHA. Figure 2 depicts the results. Figure 2 reveals a high ABS-PC and ABS content for all monitor components. PS was mainly used for M feet . In addition to the polymer type identification, M feet , M fronts and M backs of 908 monitor casings were characterised by handheld sliding spark spectroscopy to identify the presence of halogens. A total of 29% of M fronts contained chlorine and/or bromine and 28% of M backs , respectively. Less halogens were found in M feet , only 10% of the parts contained bromine and/or chlorine. The XRF results of the scrap material correlate with these results. For M backs , a total bromine content of 2.4% was measured and 0.15% for the feet. The results of the 100 unsorted TV samples shown in Figure 2 reveal that 86 specimens were composed of HIPS, nine of ABS and five of other polymer types. The XRF identified bromine contents above 0.1% in 36% of the HIPS samples. The chlorine content exceeded 0.5%, even though the bromine level was below 0.1% for another 8% of the HIPS samples. A cadmium content of 0.01% was exceeded for 19% of the samples, but only if either the bromine or chlorine content was too high as well. The bromine content of all ABS samples exceeds 0.1% and the legal threshold for cadmium is exceeded for most ABS samples. Manufacturers could be assigned to all TV parts analysed and ABS was almost exclusively used by a certain manufacturer. From these results, a halogen-free HIPS target fraction of 50% of the total TV fraction could be expected. Since no other halogen- free styrenics could be found, density separation appears to be a promising treatment to produce a pure halogen-free HIPS recy- clate. The polymer type composition of TV fronts and TV backs is similar. Comparing the XRF results of TV backs and TV fronts reveals that 37% of the backs exceeded bromine levels of 0.1% and only 6% of the fronts exceeded this value. A higher process yield could be achieved if only TV fronts were used, but since TV backs make up a bigger fraction of the WEEE stream, treating all TV components is recommended. Figure 2 depicts a rather high variety of materials in a mixed batch of SHA. Contents between 16% and 22% were identified for ABS, PS and polyolefins. Polyamide and polycarbonate could also be identified and a content of 33% of other plastics, metals and other material. The results of the static laboratory density fractionation are illustrated by Figure 3. For M&P casings, the bromine content stays below 0.1% for material densities of 1.08 g cm -3 and below, but the yield is only approximately 22% for both batches analysed. For the two batches of unsorted TV casings, legal thresholds for bromine can be kept when a density cut of 1.06 g cm -3 is applied. At this density cut, the yield is 69% and 77%. While the density fractions of both dismantlers show similar compositions for TV casings as well as for M&P casings, the two batches of SHA differ remarkably. For SHA 1 the bromine content stays below 0.1%, even in higher density fractions. Anyhow, thresholds for lead and cadmium are exceeded in this batch. The bromine content of batch SHA 2 exceeds 0.2% in the density fraction 1.07 g cm -3 < ρ < 1.08 g cm -3 . The cumulative yields of these two batches differ remarkably as the polyolefin content of SHA 1 is approximately 15% higher than that of SHA 2. Workers of the cooperating dismantling centres observed high variations of the input composition, dependent on time and delivering client. After the first coarse size reduction process, 85% to 90% of the parts are in the size range between 12 mm and 45 mm. Between 6% and 8% of the parts are smaller than 12 mm and 4% to 7% are larger than 45 mm. This particle size distribution was determined for casings of M&P, TVs and SHA. For the applied NIR separation process, particle sizes above 12 mm were necessary to achieve the best separation results relating to yield and purity. Figure 4 shows the NIR separation results for casings of M&P and SHA. Separation yield and impurities of each target fraction are depicted. TVs were mostly black and therefore not sorted by NIR separation. The achieved purities of the sorted target fractions vary between 68% and 90% for ABS, 51% and 77% for PS, and 79% and 94% for PC/ABS.] For M&P casings, 19% to 31% remained unsortable after a two-step NIR sortation. The predominant share of unsortable parts was smaller than 20 mm. The results for the M&P-X fraction in which halogenated parts were enriched, reveal a high content of ABS and only little PS and ABS-PC compared with the other M&P fractions sorted. Non-styrenic impurities of the ABS and HIPS target fraction are expected to be removed in the downstream density separation. The fraction of M&P casings contained mainly grey plastics and was thus an adequate input for the NIR-based separation. Two separation steps were necessary to achieve good yields for better product qualities. An optimised crushing, singularisation and calibration could further improve yield and purity. The unsortable rest of SHA casings amounts to 74% and was dominated by dark plastics. This observation and the results from the material characterisation lead to the decision to drop this approach. In the proceedings, the focus was put on density separation for SHA unsorted and the subfractions SHA coffee and SHA vacuum that two of the dismantling centres separate routinely from the entire batch of SHA. NIR-sorted ABS and HIPS from M&P casings were introduced to the continuous density separation process. According to the laboratory results, a density cut of 1.08 g cm -3 was applied to separate halogenated particles from M&P fractions. For TV casings and SHA fractions, a density cut of 1.06 g cm -3 was derived from the laboratory results to produce a halogen-free styrenic fraction. All batches were introduced to a density medium of 1.0 g cm -3 to separate a light, polyolefin-rich fraction. The results of the continuous density separation are depicted in Figure 5. NIR-sorted ABS and HIPS from M&P and M&P-noX were separated in the Sorticanter ® by a two-step density separation. The density cut at 1.0 g cm -3 is redundant since no polyolefins were present. The yield for the halogen-free ABS target fraction amounted to 27% and 45% for M&P and M&P-noX, respectively. The HIPS from M&P and M&P-noX were mixed to have a sufficient amount to be introduced to the Sorticanter ® . A yield of 56% could be achieved for the halogen-free HIPS target fraction. All bromine levels of the target fraction between 1.0 and 1.08 g cm -3 were below 0.1%. Manual pre-sorting by sliding spark spectroscopy could increase the yield of the density separation process, but still a rather high percentage ended up in the heavy fraction. Thus, the reliability of the SSS3 results must be questioned. As the SSS3 device was applied by unskilled staff, this unreliability may possibly be attributed to handling mistakes. By continuous density separation of TV casings, polypropylene ends up in the light fraction and the flame-retarded styrenics ...
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... fractions of the crushing process to determine the particle size distribution. To characterise the big batches of M&P casings, TV casings and SHA static density fractionation was performed on a laboratory scale with samples from the coarse particle size reduction. Dipotassium phosphate was dissolved in water to create a density media of 1.0 g cm -3 , 1.03 g cm -3 , 1.06 g cm -3 , 1.07 g cm -3 , 1.08 g cm -3 and 1.09 g cm -3 . In the first step, the lightest density fraction was separated from 10 kg of each batch, the material was dried and the mass balances were recorded. The bromine content of the light fraction was measured by XRF. The heavy fraction of this first step was then introduced to the density medium of 1.03 g cm -3 , the material was dried, mass balances were recorded and the bromine content of the lighter fraction was measured. This procedure was repeated with media of higher densities until the bromine value exceeded 0.1% to determine which density cuts are expedient on a technical scale to produce legally marketable recyclates with high process yields. To determine tensile and impact strength of recycled styrenics and polyolefins, test specimen were produced. The recyclates were homogenised and cleaned in a single-screw extruder with a screen of 150 μm. The extrusion temperatures varied between 180 °C and 230 °C and pressures up to 200 bar were applied. The extruded products were granulated and test specimen were produced by injection moulding at 240 °C for ABS, polystyrene (PS) and ABS-PC, and 190 °C for PP. The injection moulding dies had temperatures between 45 °C and 60 °C. Tensile and impact (Charpy method) tests were performed in accordance to standardised methods (DIN EN ISO 3167, DIN EN ISO 179). Dismantling of TVs, monitors, printers and vacuum cleaners was performed manually to remove the panel glass, cartridges and motors in German dismantling centres. Coffee dispensers and vacuum cleaners were separated by hand sorting from batches of SHA. One dismantler applied sliding spark spectroscopy to identify halogens in casings of TVs and M&P, and to separate halogenated parts from halogen-free ones. For material sorting, manual dismantling, hand-sorting, handheld spectroscopic devices, crushing, automated NIR or continuous density separation and combinations of these techniques were applied. Figure 1 depicts the treatment scheme for the different input streams. Two basic approaches were chosen for material sorting. M&P casings were sorted by NIR separation and the particle size of the sorted ABS and PS fractions was further reduced to separate halogenated parts by density separation. The NIR-based separation approach was also tested for SHA casings, but was not pursued owing to insufficient process efficiency. Because of the high content of dark parts, TV casings, mixed SHA fractions, SHA coffee and SHA vacuum were directly introduced to the density separation process. The separated casings were pressed and shipped to a business partner who crushed the material in a rotary shear and granulator (both Andritz-MEWA GmbH, Gechingen, Germany). Fine grains were separated by a zigzag air-classifier (AUT GmbH, Chemnitz, Germany). Iron was extracted by an overhead suspension magnet and a neodymium magnet (both Steinert Elektromagnetebau, Cologne, Germany), and non-ferrous metals were removed by an eddy current separa- tor. Batches for the downstream continuous density separation were introduced to a hammer mill (Herbold, Meckesheim, Germany) for crushing to particle sizes below 8 mm. Automated NIR separation was tested on a technical scale with a UNISORT® NIR separation system (RTT-Steinert GmbH, Zittau, Germany). The first sorting step was performed with a multiplex sensor. The remaining fraction of parts that could not be identified was sorted once more by applying a camera system with an increased sensor resolution. Technical scale NIR separation was performed for M&P casings and for a batch of mixed SHA. On a technical scale, continuous density separation was performed with the Sorticanter ® (Flottweg, Vilsbiburg, Germany). The density media were produced by dissolving dipotassium phosphate in water to produce a density media of 1.0 g cm -3 , 1.06 g cm -3 and 1.08 g cm -3 . Which density cuts were chosen for which fraction was decided according to the results of the material characterisation. An input of 100 kg was the minimum amount for the Sorticanter ® to obtain separation results with repetitious accuracy. Continuous density separation was applied to sort halogen-free PS fractions from TV casings and halogen-free ABS and PS fractions of NIR pre-sorted M&P casings. From a batch of mixed SHA and from the sub-fractions SHA coffee and SHA vacuum , polyolefins and halogen-free styrenics were separated. Handheld spectroscopic polymer-type identification was used to get an idea of the polymer-type composition of monitor and TV components and mixed SHA. Figure 2 depicts the results. Figure 2 reveals a high ABS-PC and ABS content for all monitor components. PS was mainly used for M feet . In addition to the polymer type identification, M feet , M fronts and M backs of 908 monitor casings were characterised by handheld sliding spark spectroscopy to identify the presence of halogens. A total of 29% of M fronts contained chlorine and/or bromine and 28% of M backs , respectively. Less halogens were found in M feet , only 10% of the parts contained bromine and/or chlorine. The XRF results of the scrap material correlate with these results. For M backs , a total bromine content of 2.4% was measured and 0.15% for the feet. The results of the 100 unsorted TV samples shown in Figure 2 reveal that 86 specimens were composed of HIPS, nine of ABS and five of other polymer types. The XRF identified bromine contents above 0.1% in 36% of the HIPS samples. The chlorine content exceeded 0.5%, even though the bromine level was below 0.1% for another 8% of the HIPS samples. A cadmium content of 0.01% was exceeded for 19% of the samples, but only if either the bromine or chlorine content was too high as well. The bromine content of all ABS samples exceeds 0.1% and the legal threshold for cadmium is exceeded for most ABS samples. Manufacturers could be assigned to all TV parts analysed and ABS was almost exclusively used by a certain manufacturer. From these results, a halogen-free HIPS target fraction of 50% of the total TV fraction could be expected. Since no other halogen- free styrenics could be found, density separation appears to be a promising treatment to produce a pure halogen-free HIPS recy- clate. The polymer type composition of TV fronts and TV backs is similar. Comparing the XRF results of TV backs and TV fronts reveals that 37% of the backs exceeded bromine levels of 0.1% and only 6% of the fronts exceeded this value. A higher process yield could be achieved if only TV fronts were used, but since TV backs make up a bigger fraction of the WEEE stream, treating all TV components is recommended. Figure 2 depicts a rather high variety of materials in a mixed batch of SHA. Contents between 16% and 22% were identified for ABS, PS and polyolefins. Polyamide and polycarbonate could also be identified and a content of 33% of other plastics, metals and other material. The results of the static laboratory density fractionation are illustrated by Figure 3. For M&P casings, the bromine content stays below 0.1% for material densities of 1.08 g cm -3 and below, but the yield is only approximately 22% for both batches analysed. For the two batches of unsorted TV casings, legal thresholds for bromine can be kept when a density cut of 1.06 g cm -3 is applied. At this density cut, the yield is 69% and 77%. While the density fractions of both dismantlers show similar compositions for TV casings as well as for M&P casings, the two batches of SHA differ remarkably. For SHA 1 the bromine content stays below 0.1%, even in higher density fractions. Anyhow, thresholds for lead and cadmium are exceeded in this batch. The bromine content of batch SHA 2 exceeds 0.2% in the density fraction 1.07 g cm -3 < ρ < 1.08 g cm -3 . The cumulative yields of these two batches differ remarkably as the polyolefin content of SHA 1 is approximately 15% higher than that of SHA 2. Workers of the cooperating dismantling centres observed high variations of the input composition, dependent on time and delivering client. After the first coarse size reduction process, 85% to 90% of the parts are in the size range between 12 mm and 45 mm. Between 6% and 8% of the parts are smaller than 12 mm and 4% to 7% are larger than 45 mm. This particle size distribution was determined for casings of M&P, TVs and SHA. For the applied NIR separation process, particle sizes above 12 mm were necessary to achieve the best separation results relating to yield and purity. Figure 4 shows the NIR separation results for casings of M&P and SHA. Separation yield and impurities of each target fraction are depicted. TVs were mostly black and therefore not sorted by NIR separation. The achieved purities of the sorted target fractions vary between 68% and 90% for ABS, 51% and 77% for PS, and 79% and 94% for PC/ABS.] For M&P casings, 19% to 31% remained unsortable after a two-step NIR sortation. The predominant share of unsortable parts was smaller than 20 mm. The results for the M&P-X fraction in which halogenated parts were enriched, reveal a high content of ABS and only little PS and ABS-PC compared with the other M&P fractions sorted. Non-styrenic impurities of the ABS and HIPS target fraction are expected to be removed in the downstream density separation. The fraction of M&P casings contained mainly grey plastics and was thus an adequate input for the NIR-based separation. Two separation steps were necessary to achieve good yields for better product qualities. An optimised crushing, singularisation and calibration could further improve yield and ...
Citations
... Sorting lines sort only one plastic per step; hence, sorting plants operate with a series of such lines. However, due to economic reasons, they focus on a limited number of plastic types (Arends et al. 2015). ...
... Legacy additives such as certain BFRs or phthalates can only be separated by specific technologies, such as density separation or spectroscopic sorting, as described for plastics from WEEE (UNEP 2021c). Spectroscopic sorting (laser spectroscopy) and density separation have proven to produce ABS, PP and PS recyclates with acceptable mechanical properties and BFR levels that comply with the RoHS directive and are below a low POP content of 1,000 or 500 mg/kg (Arends 2014;Arends et al. 2015, Dewulf et al. 2019 The recycling of plastic packaging waste also exemplifies the challenges of sorting monoplastics such as PE, PP, PS and PET from the bulk of the packaging. Labels on the plastic hinder identification. ...
https://www.unep.org/resources/report/chemicals-plastics-technical-report
The report provides state of knowledge on chemicals in plastics and based on compelling scientific evidence calls for urgent action to address chemicals in plastics as part of the global action on plastic pollution.
Overview of the report:
The “Chemicals in Plastics: A Technical Report” aims to inform the global community about the often-overlooked chemical-related issues of plastic pollution, particularly their adverse impacts on human health and the environment as well as on resource efficiency and circularity. Based on compelling scientific evidence, it further highlights the urgent need to act and outlines possible areas for action. It also aims to support the negotiation process to develop the instrument on plastic pollution based on United Nations Environment Assembly resolution 5/14. The report outlines a set of credible and publicly available scientific studies and initiatives focused on chemicals in plastics and the science-policy interface.
The report was developed by UNEP in cooperation with the Secretariat of the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, the Rotterdam Convention on the Prior Informed Consent Procedure for Certain Hazardous Chemicals and Pesticides in International Trade, and the Stockholm Convention on Persistent Organic Pollutants, with lead authors from the International Panel on Chemical Pollution, as well as contributions from key experts.
Some key findings:
Based on the latest studies, more than 13,000 chemicals have been identified as associated with plastics and plastic production across a wide range of applications.
Ten groups of chemicals (based on chemistry, uses, or sources) are identified as being of major concern due to their high toxicity and potential to migrate or be released from plastics, including specific flame retardants, certain UV stabilizers, per- and polyfluoroalkyl substances (PFASs), phthalates, bisphenols, alkylphenols and alkylphenol ethoxylates, biocides, certain metals and metalloids, polycyclic aromatic hydrocarbons, and many other non-intentionally added substances (NIAS).
Chemicals of concern have been found in plastics across a wide range of sectors and products value chains, including toys and other children's products, packaging (including food contact materials), electrical and electronic equipment, vehicles, synthetic textiles and related materials, furniture, building materials, medical devices, personal care and household products, and agriculture, aquaculture and fisheries.
Chemicals of concern in plastics can impact our health and our environment: Extensive scientific data on the potential adverse impacts of about 7,000 substances associated with plastics show that more than 3,200 of them have one or more hazardous properties of concern.
Women and children are particularly susceptible to these toxic chemicals. Exposures can have severe or long-lasting adverse effects on several key period of a women’s life and may impact the next generations. Exposures during fetal development and in children can cause, for example, neurodevelopmental / neurobehavioural related disorders. Men are not spared either, with latest research documenting substantial detrimental effects on male fertility due to current combined exposures to hazardous chemicals, many of which are associated with plastics.
Chemicals of concern can be released from plastic along its entire life cycle, during not only the extraction of raw materials, production of polymers and manufacture of plastic products, but also the use of plastic products and at the end of their life, particularly when waste is not properly managed, finding their way to the air, water and soils.
Existing evidence calls for urgent action to address chemicals in plastics as part of the global action on plastic pollution, to protect human health and the environment, and transition to a toxic-free and sustainable circular economy.
UNEP acknowledges the financial support from the Government of Norway, the Government of Sweden and the Government of Switzerland, for the development of the report.
... The recycling is of high quality despite progressive thermal-mechanical degradation. Arends et al. [45] pointed out that the lower recycling quality achieved by remelting, semi-volatile hazardous additives such as flame retardants, plasticizers, and stabilizers can only be removed by precise presorting, presorting by density separation, Xray fluorescence (XRF), or spectroscopic near-infrared (NIR) sorting technologies, resulting in a high rejection rate for plastics with a high content of legacy additives. Schyns and Shaver [46] studied the mechanical recycling of five major packaging materials: PET, PE, PP, PS, and PVC, and indicated that reprocessing leads to polymer degradation that requires mechanisms and strategies to improve recycling. ...
Challenges associated with plastic waste management range from littering to high collection costs to low recycling rates. Effective collection of plastics is obviously an important step in the management of plastic waste and has an impact on recycling rates. For this reason, several countries have transformed their collection systems in recent decades. Collecting more plastic packaging comes at a cost, as the feedstock for the sorting process becomes more complex and leads to cross-contamination within the sorted fractions. Therefore, a balance must be obtained between some elements, such as the design of packaging, collection and recycling rates, and finally, the quality of fractions that have been sorted. Further investment to improve pretreatment, sorting, and recycling technologies and simpler recyclable packaging designs are, therefore, key to further increasing plastic recycling rates. It is essential to possess more data, especially on the type of containers and plastics, and examine how often unsorted waste is collected. The automated waste collection monitoring system is a step forward in automating manual waste collection and sorting. Multi-sensory artificial intelligence (AI) for sorting plastic waste and the blockchain sorting platform for the circular economy of plastic waste are forward-looking activities that will increase the efficiency of recycling plastic waste. This review focuses on the development of collection systems and sorting processes for post-consumer plastic recycling. The focus is on best practices and the best available technology. Separate collection systems for recyclable plastics are presented and discussed along with their respective technical collection and sorting solutions, taking into consideration that progress in separation and sorting systems are implicitly linked to approaches to waste collection.
... A sorting method using infrared rays or X-rays has been extensively studied in recent years [170][171][172][173][174]. For mechanical recycling, it is also necessary to presort by type of plastic such as ABS, HIPS, and PS, which increases the processing cost. ...
Research into plastic recycling is rapidly increasing as ocean and land pollution and ecosystem degradation from plastic waste is becoming a serious concern. In this study, we conducted a systematic review on emerging research topics, which were selected from 35,519 studies on plastic recycling by bibliometrics analysis. Our results show that research on the biodegradability of plastics, bioplastics, life cycle assessment, recycling of electrical and electronic equipment waste, and the use of recycled plastics in construction has increased rapidly in recent years, particularly since 2016. Especially, biodegradability is the most emerging topic with the average year of publication being 2018. Our key finding is that many research area is led by developed countries, while the use of recycled plastics in the construction sector is being actively explored in developing countries. Based on our results, we discuss two types of recycling systems: responsible recycling in the country where plastic waste is generated and promoting recycling through the international division of labor between developed and developing countries. We discuss the advantages and disadvantages of both approaches and propose necessary measures for sustainable and responsible production and consumption of plastics such as waste traceability system and technology transfer between developed and developing countries.
... If proper collection, dismantling, and treatment of household appliances along with the plastics contained are carried out, the wellbeing of the environment will be better secured (Tian, 2016). HAP after proper collection and recycling can also be very valuable resources, relieving the huge demand for virgin polymers, as demonstrated and supported by multiple previous studies (Ardente et al., 2015;Arends et al., 2015;Hall and Williams, 2007;He et al., 2006;Wu et al., 2020). The markets for reprocessed HAP are growing, and usually have higher market values than other grades (Fisher et al., 2003). ...
China has the highest level of plastic production and consumption in the world. The plastic waste ban has resulted in a lack of raw materials for plastic reprocessing, while household appliance-related plastic (HAP), as a high-value and high-quality plastic waste source, receives great attention to fill such a gap. As HAP is scattered and has been rapidly increasing, a better understanding of the spatial-temporal patterns of HAP waste is critical. For the first time, this study quantifies the stocks and flows of plastics contained in five categories of household appliances (refrigerator, washing machine, air conditioner, TV, and computer) in China over 1978–2016 and maps their province-specific distribution through a dynamic stock-driven material flow analysis model. We find that (i) the HAP stocks are growing rapidly to reach around 25.4 million tonnes (MT) in 2016 and the HAP waste generated in 2016 is over 2 MT while the dismantling capacity is failing to catch up; (ii) the HAP waste in southeastern provinces is notably more than in northwestern provinces by approximately 11 times; (iii) washing machines (37%) and refrigerators (24%) are the major types of household appliances that contribute most to HAP waste generation; (iv) PP (38%) and PS (34%) are the major plastic types in HAP waste. These findings can provide quantitative references for the government to arrange waste management facilities, improve recycling capacities of dismantling companies, and promote coordinated efforts from multiple stakeholders to achieve efficient waste management of HAP.
... Classification by NIR is not precise since materials are mainly dark-colored which makes detection difficult by the equipment. Additionally, as it was aforementioned, they are mainly styrenics resins and, consequently, their chemical similarities also contribute to complicate the detection (Da Silva and Wiebeck 2020; Arends et al. 2015). In this way, sorting is commonly performed manually which also is not accurate and increases labor costs. ...
... Sorting is not accurate, as it was demonstrated previously with the presence of AN in HIPS WEEE. Even using specific techniques and equipment these difficulties persist since ABS and HIPS are very similar resins from the compositional point of view and they are generally darkcolored, which difficult their differentiation (Da Silva and Wiebeck 2020; Arends et al. 2015). Because of these reasons, obtained results are very promising for the recycling industry. ...
E-waste management is becoming a very challenging subject since it is very multidisciplinary, encompassing concepts such as circular economy, closed-loop supply chains, supply chain risk management, and supply chain resilience. These pillars must be strongly supported by a huge amount of quality data, therefore, opening an important interface with the concept of smart cities. Among the main challenges, is the need to motivate the customers to collaborate, creating a culture of reusing and recycling end-of-life products. In addition, it is crucial to develop reverse recycling channels suitable to each client and enabled by an effective logistics network design. Despite the relevance of this topic, many significant gaps can be pointed out, since there are still few relevant papers. Thus, there is a substantial necessity of understanding what have been done by scholars to establish the state of the art. In this sense, this paper has the objective of mapping the state of the art of e-waste management through a bibliometric study. Among the main results, we highlight the mapping of the state of the art composed of the literature statistics.
... Classification by NIR is not precise since materials are mainly dark-colored which makes detection difficult by the equipment. Additionally, as it was aforementioned, they are mainly styrenics resins and, consequently, their chemical similarities also contribute to complicate the detection (Da Silva and Wiebeck 2020; Arends et al. 2015). In this way, sorting is commonly performed manually which also is not accurate and increases labor costs. ...
... Sorting is not accurate, as it was demonstrated previously with the presence of AN in HIPS WEEE. Even using specific techniques and equipment these difficulties persist since ABS and HIPS are very similar resins from the compositional point of view and they are generally darkcolored, which difficult their differentiation (Da Silva and Wiebeck 2020; Arends et al. 2015). Because of these reasons, obtained results are very promising for the recycling industry. ...
Electronic waste (e-waste) is gaining the attention of scholars since its supply chain offers valuable materials that can be recovered, generating resilience to supply chains and the environment. To recover these materials, it is necessary to establish closed-loop supply chains, enabling a circular economy logic. In this sense, supply chain flows must be designed to retrieve these values and mitigate the risks. Furthermore, collection points must be strategically positioned to make this operation feasible, integrating the concept of smart cities. Therefore, this article proposes a conceptual analysis of the literature and, as its main result, presents an integrated framework considering five dimensions: (i) E-waste management, (ii) Supply Chain Resilience—SCRes, (iii) Circular Economy, (iv) Closed-loop supply chains, and (v) Smart cities.
KeywordsE-Waste managementSupply chain resilienceCircular economyClosed-loop supply chainsSmart cities
... Sink-float separation in a centrifugal force separator achieved a separation of PO (Polyolefins) from PCP waste with a very high PO content (> 90 wt%) [3]. Finally, to accentuate the density separation's capabilities in sorting, it was also found that sink-float separators can produce halogen-free HIPS (High Impact Polystyrene) streams as it was applied to sort halogenfree PS fractions from TV casings and halogen free ABS and PS fractions from monitors and printer casings [2]. Furthermore, density separation combined with a solvent based process was applied for sorting halogenated styrenics from WEEE plastics [18]. ...
The Circular Economy Action Plan, in the context of the European Green deal, introduces new policies which promote a more sustainable use of plastics. These policies also prioritize the optimization of plastics recycling processes by increasing both the amount and quality of plastic recyclates produced, which is to a large extend defined by the purity and yield achieved by state-of-the-art plastic sorting processes. Therefore, the presented research focuses on developing a Computational Fluid Dynamics (CFD) based model to predict and obtain better insights in the separation performance of sink float separators, more specifically Dense Medium Drum (DMD) separators. The flow inside the drum is simulated by adopting an Euler-Lagrangian approach, a widely employed model for the numerical simulation of multi-phase flows including solid particles. To validate the simulations, a transparent lab-scale sink float separator, using the principle of a rotating drum, is constructed. In all experiments, water is used as medium. The separation objects represent a single polymer type which is fed to the drum. For the present work these are Polypropylene (PP), Polystyrene (PS), High Density Polyethylene (HDPE) Acrylonitrilic Butadiene Styrene (ABS), Polycarbonate Acrylonitrile Butadiene Styrene (PC/ABS) grains with a length scale of 3 mm and High Density Polyethylene grains of 4 mm. The separation number is easily expressed as the ratio of objects leaving the sink or float outlet depending on the type of the polymer density to the total amount of separation objects. It was found that the separation numbers computed by the numerical model for all separated objects agree with the measured ones within a maximum error of 7%. When comparing the hydrophilic ABS to the hydrophobic PS, which have similar densities, it is shown that air bubbles have a large influence on the separation efficiency. With the validated CFD model, essential insights are gained on the physics of the flow field inside the separator which help in further optimizing these devices to achieve higher separation efficiencies.
... Most bromine was found in PS and ABS, whereas almost no bromine was found in PC and PC/ABS as earlier reported by Arends et al. [32]. The measured bromine and chlorine contents of PC, PC/ABS were below 2000 ppm for each sample. ...
This paper describes a study for waste of electrical and electronic equipment (WEEE) to characterise the plastic composition of different mixed plastic fractions. Most of the samples studied are currently excluded from material recycling and arise as side streams in state-of-the-art plastics recycling plants. These samples contain brominated flame retardants (BFR) or other substances of concern listed as persistent organic pollutants or in the RoHS directive. Seventeen samples, including cathode ray tube (CRT) monitors, CRT televisions, flat screens such as liquid crystal displays, small domestic appliances, and information and communication technology, were investigated using density- and dissolution-based separation processes. The total bromine and chlorine contents of the samples were determined by X-ray fluorescence spectroscopy, indicating a substantial concentration of both elements in density fractions above 1.1 g/cm3, most significantly in specific solubility classes referring to ABS and PS. This was further supported by specific flame retardant analysis. It was shown that BFR levels of both polymers can be reduced to levels below 1000 ppm by dissolution and precipitation processes enabling material recycling in compliance with current legislation. As additional target polymers PC and PC-ABS were also recycled by dissolution but did not require an elimination of BFR. Finally, physicochemical investigations of recycled materials as gel permeation chromatography, melt flow rate, and differential scanning calorimetry suggest a high purity and indicate no degradation of the technical properties of the recycled polymers.
... Some EEE have a higher plastic content. These devices [17] and polymers by weight found in WEEE [9] [29] Different electronic devices from commercial entities and residences FTIR and inductively-coupled plasma optical emission spectroscopy (ICP-OES) [24] TVs, monitors, printers and small appliances NIRS and energy-dispersive X-ray fluorescence (ED-XRF) [30] Content courtesy of Springer Nature, terms of use apply. Rights reserved. ...
... The solvents used exhibit low boiling points (< 100 °C) and can be recovered by fractional distillation in order to separate them from the brominated flame retardants [44]. The diversity of polymers and additives in WEEE make recycling difficult; however, some studies [24,28,30] used more advanced techniques to identify and separate polymers [44], making it possible to recycle them as efficiently as possible. ...
Acrylonitrile–butadiene–styrene (ABS) copolymer and high-impact polystyrene (HIPS) are the plastics most commonly found in waste electrical and electronic equipment (WEEE), although properties generally decline with recycling. Technical studies are important in assessing the properties of recycled plastics and obtaining better evidence of their return or not to the same production cycle, through a study of their impacts and life cycle assessment (LCA). This article aimed at a literature search for information that demonstrates the importance of considering the technical property results of LCA studies on WEEE plastics. LCA studies show that recycling WEEE plastics, when compared with virgin raw material, prevents 87% of ABS gas emissions, in addition to reducing energy consumption by up to 90% for ABS and HIPS. However, some technical properties of recycled WEEE polymer material, such as impact strength and ultimate elongation, decline when compared to virgin materials, which may hinder their reinsertion into the same production cycle. These properties can be enhanced by preparing compatible mixtures of ABS and HIPS, or by mixing them with virgin polymers. Recycled ABS (not mixed with another material) can return to the same production cycle when the goal is to preserve the modulus of elasticity. Studies that investigate properties using LCA are scarce. However, they are important in determining the viability of the material returning or not to the same production cycle, which would impact the process and produce different LCA results. Recycled ABS and HIPS polymers from WEEE can return to the same function even if some properties decline, since properties can be improved when the polymers are properly mixed or made compatible, thereby lowering costs and primarily minimizing the negative environmental impacts.
... The WEEE recycling process involves dismantling, shredding, and crushing. Therefore, a singular crushing process to deal with WEEE will produce electronic-waste shredder residue (ESR) containing plastic-rich fractions, although it is considered a low value product or even waste (Arends et al. 2015). However, the plastic fraction in ESR has usually not been taken seriously due to the focus on metal recovery rather than recovering plastic for recycling purpose. ...
This study reports the selective hydrophilization of the ABS/PC blend surface using the peroxide-sonochemical system and then its selective separation by froth flotation technique from other ABS-based plastics (ABS, ABS/PMMA) and PS/HIPS in electronic shredder residue (ESR). FT-IR and XPS measurements confirm that the hydrophilic moiety development on the ABS/PC surface led to increasing the wettability of ABS/PC and then decreased its floatability. The confocal scanning results also support the enhancement of microscale roughness of the treated ABS/PC surface. The enhanced surface roughness is attributed to the oxidative process which degrades hydrophobic moieties and promotes hydrophilic functional groups on the ABS/PC surface using commercial oxidant peroxide and ultrasound. This study also investigated removal of Br-containing compounds on the ABS/PC surface. The optimum conditions for selectively ABS/PC separation are peroxide concentration 2%, power cycle 70%, treatment time 5 min, temperature 50 °C, floating agent concentration 0.4 mg/L, flotation time 2 min, and airflow rate 0.5 L/min. ABS/PC was selectively separated from ESR styrene plastics with high recovery and purity of 98.9% and 99.8%, respectively. Hence, the developed novel surface treatments having removal of hazardous Br chemicals and none-formation of secondary pollutants should be applied for upgrading plastic recycling quality.
