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Waste plastics

New pigments for packaging intended to be compostable

Producers of plastic articles are increasingly using polymers that are compostable. Clariant’s business unit Pigments wants to contribute to this growth in compostable plastic articles, with a range of certified “OK compost Industrial” pigments, offering customers new coloring opportunities.

The organic pigments are certified with the “OK compost Industrial” label. (Source: Clariant/TÜV Austria)

Nine selected products in the ranges PV Fast and Graphtol now feature the label “OK compost Industrial”, that meet the requirements of the European Union EN 13432: 2000 standard when not used above the maximum concentration in the final application, representing a significant contribution to sustainability.

“We are proud of this development that is part of our strategy to offer solutions for more sustainable packaging and to strengthen our product portfolio,” said Andreas Buder, Technical Marketing Manager Plastics at Clariant. “This certification allows our customers to use bright colors in their biodegradable products, since they are suitable for industrial composting.”

The PV Fast and Graphtol range of pigment powders are high performance organic pigments. Both product ranges are used in various applications in the consumer goods sector, such as sensitive food contact packaging, plastics tableware/dishware or toys.
The coloration of biodegradable polymers requires the pigments to meet certain characteristics in order to be considered compostable. For processing through organic recovery facilities, this requires a low heavy metal and fluorine content, and no ecotoxicity towards plants.

RecyClass tests functional barriers in PP containers

EVOH which is combined with a polypropylene-grafted maleic anhydride (PP-g-MAH, with MAH > 0.1%) tie layer does not jeopardize the recyclability of a package, the findings demonstrated.

Testing was performed on a PP bottle consisting of 6% of EVOH with 3% of PP-grafted-MAH tie layers (by weight), as well as on a PP sheet with the same levels of the EVOH and PP-g-MAH.

The German lab Institut für Kunststofftechnologie und -recycling (IKTR) was tasked with carrying out the analysis following the RecyClass Recyclability Evaluation Protocol for PP containers.

The results show that concentration of up to 6% of EVOH (with respect to overall packaging weight) tied with PP grafted maleic anhydride will not have a negative impact on the PP rigids and, therefore, is fully compatible with the respective stream. Additionally, same structure with concentrations higher than 6% of EVOH were found to have limited recycling compatibility. Both conclusions are applicable to all types of PP rigid packaging, that includes not only bottles and sheets that were tested but also tubes, pots and trays.

The recycled material coming from this packaging can be used in high-end applications including bottles and sheets.

RecyClass recommends to compatibilise the EVOH-barrier layer with a minimal amount of tie layer, following a ratio below two of EVOH versus tie layer. The recommendations described above are not to be universally applied to other types of tie layers, as their compatibility must be further tested.

The aforementioned results are used to update the RecyClass Design for Recycling Guidelines for PP Natural and Coloured Containers and respectively the RecyClass Online Tool.

Moreover, these findings are in line with the previous testing done on EVOH in HDPE containers released last year. They contribute to increasing the knowledge about the functional barriers and their impact on the recyclability of plastic packaging.

RecyClass tests functional barriers in PP containers

EVOH which is combined with a polypropylene-grafted maleic anhydride (PP-g-MAH, with MAH > 0.1%) tie layer does not jeopardize the recyclability of a package, the findings demonstrated.

Testing was performed on a PP bottle consisting of 6% of EVOH with 3% of PP-grafted-MAH tie layers (by weight), as well as on a PP sheet with the same levels of the EVOH and PP-g-MAH.

The German lab Institut für Kunststofftechnologie und -recycling (IKTR) was tasked with carrying out the analysis following the RecyClass Recyclability Evaluation Protocol for PP containers.

The results show that concentration of up to 6% of EVOH (with respect to overall packaging weight) tied with PP grafted maleic anhydride will not have a negative impact on the PP rigids and, therefore, is fully compatible with the respective stream. Additionally, same structure with concentrations higher than 6% of EVOH were found to have limited recycling compatibility. Both conclusions are applicable to all types of PP rigid packaging, that includes not only bottles and sheets that were tested but also tubes, pots and trays.

The recycled material coming from this packaging can be used in high-end applications including bottles and sheets.

RecyClass recommends to compatibilise the EVOH-barrier layer with a minimal amount of tie layer, following a ratio below two of EVOH versus tie layer. The recommendations described above are not to be universally applied to other types of tie layers, as their compatibility must be further tested.

The aforementioned results are used to update the RecyClass Design for Recycling Guidelines for PP Natural and Coloured Containers and respectively the RecyClass Online Tool.

Moreover, these findings are in line with the previous testing done on EVOH in HDPE containers released last year. They contribute to increasing the knowledge about the functional barriers and their impact on the recyclability of plastic packaging.

NONTOX Project to recover contaminated plastics

Increasing plastic recycling rates is key to creating the circular economy of plastics promoted by the European Union. It is therefore essential for research to continue developing new recycling processes, including procedures to recover plastic waste containing hazardous substances and then use it to produce safe, high-quality plastic products. The European NONTOX Project aims to eliminate hazardous and unpleasant substances from plastic waste and thus convert non-recyclable plastics and recycling waste into new resources. AIMPLAS, the Plastics Technology Centre, is participating in the project.

The research developed by the different project partners will focus on the recovery of plastic materials from waste electrical and electronic equipment (WEEE), end-of-life vehicles (ELV), and construction and demolition waste (CDW), all of which contain hazardous additives and unpleasant compounds such as flame retardants, stabilizers and filling materials. Two different technologies will be used (Extruclean and CreaSolv®) to eliminate these hazardous substances from waste plastics such as ABS, EPS, PS, HIPS, PE and PP, which jointly account for about half of EU demand for plastics, hence the importance of recycling plastics rather than continuing the current practice of landfilling or incinerating a significant part of this waste.

The NONTOX Project, funded through the European Union’s research and innovation programme Horizon 2020, grant agreement 820895, is coordinated by the VTT Technical Research Centre of Finland. The other consortium members are AIMPLAS, Fraunhofer, Università degli studi della Campania Luigi Vanvitelli, Treee, Fundación IMDEA Energía, Stena Recycling International AB, Galea Polymers, ECODOM – Consorzio Italiano per il Recupero e Riciclaggio Elettrodomestici, Norner Research AS, Aalto University and Coolrec.

NONTOX Project to recover contaminated plastics

Increasing plastic recycling rates is key to creating the circular economy of plastics promoted by the European Union. It is therefore essential for research to continue developing new recycling processes, including procedures to recover plastic waste containing hazardous substances and then use it to produce safe, high-quality plastic products. The European NONTOX Project aims to eliminate hazardous and unpleasant substances from plastic waste and thus convert non-recyclable plastics and recycling waste into new resources. AIMPLAS, the Plastics Technology Centre, is participating in the project.

The research developed by the different project partners will focus on the recovery of plastic materials from waste electrical and electronic equipment (WEEE), end-of-life vehicles (ELV), and construction and demolition waste (CDW), all of which contain hazardous additives and unpleasant compounds such as flame retardants, stabilizers and filling materials. Two different technologies will be used (Extruclean and CreaSolv®) to eliminate these hazardous substances from waste plastics such as ABS, EPS, PS, HIPS, PE and PP, which jointly account for about half of EU demand for plastics, hence the importance of recycling plastics rather than continuing the current practice of landfilling or incinerating a significant part of this waste.

The NONTOX Project, funded through the European Union’s research and innovation programme Horizon 2020, grant agreement 820895, is coordinated by the VTT Technical Research Centre of Finland. The other consortium members are AIMPLAS, Fraunhofer, Università degli studi della Campania Luigi Vanvitelli, Treee, Fundación IMDEA Energía, Stena Recycling International AB, Galea Polymers, ECODOM – Consorzio Italiano per il Recupero e Riciclaggio Elettrodomestici, Norner Research AS, Aalto University and Coolrec.

Masotina chooses ZenRobotics as partner for AI-based sorting

The Masotina S.p.A. plant in Milan, Italy, is a household waste plastic recovery and sorting facility with a total capacity of 355.000 tons per year. The facility has been retrofitted in recent years to include the most sophisticated recycling automation technologies to separate out recyclable waste plastics.

Italian waste management company Masotina’s S.p.A. facility is one of the largest material recovery facilities (MRF) in Europe that receives, sorts, separates and prepares recyclable household waste plastics. Masotina has made substantial investments in recent years into advanced automation and recycling technologies to gain a leadership position in the plastic waste recovery and recycling market. By partnering with ZenRobotics, Masotina expands its technology leadership to include AI-based waste sorting robotics at its flagship facility.

The robustly automated Masotina S.p.A. household waste plastic sorting facility is located near Milan and has a yearly capacity of 250.000 tons. The facility has been retrofitted in recent years to feature automated sorting and selection lines that make use of the highest recycling technology to separate out recyclable waste plastics through a combination of optical, mechanical and manual sorting. One of the latest additions is the ZenRobotics Fast Picker sorting station that performs quality control at the facility, improving efficiency and reducing the need for manual sorting.

The facility separates household waste plastics coming mostly from municipal collection. Plastic waste is first sorted from other valuable recyclable materials like paper, cardboard, aluminum, tinfoil, polylaminates and inert. Then it is separated by polymer and color to maximize the recycle-reuse value of plastic. The job of the ZenRobotics Fast Picker is to ensure high output purity for clear PET by removing contaminants and taking out other valuable recyclable polymers such as HDPE that are returned back to the recycling loop. Thanks to its compact size, the ZenRobotics Fast Picker has been integrated into the existing sorting line despite very tight spaces at the facility.

Masotina chooses ZenRobotics as partner for AI-based sorting

The Masotina S.p.A. plant in Milan, Italy, is a household waste plastic recovery and sorting facility with a total capacity of 355.000 tons per year. The facility has been retrofitted in recent years to include the most sophisticated recycling automation technologies to separate out recyclable waste plastics.

Italian waste management company Masotina’s S.p.A. facility is one of the largest material recovery facilities (MRF) in Europe that receives, sorts, separates and prepares recyclable household waste plastics. Masotina has made substantial investments in recent years into advanced automation and recycling technologies to gain a leadership position in the plastic waste recovery and recycling market. By partnering with ZenRobotics, Masotina expands its technology leadership to include AI-based waste sorting robotics at its flagship facility.

The robustly automated Masotina S.p.A. household waste plastic sorting facility is located near Milan and has a yearly capacity of 250.000 tons. The facility has been retrofitted in recent years to feature automated sorting and selection lines that make use of the highest recycling technology to separate out recyclable waste plastics through a combination of optical, mechanical and manual sorting. One of the latest additions is the ZenRobotics Fast Picker sorting station that performs quality control at the facility, improving efficiency and reducing the need for manual sorting.

The facility separates household waste plastics coming mostly from municipal collection. Plastic waste is first sorted from other valuable recyclable materials like paper, cardboard, aluminum, tinfoil, polylaminates and inert. Then it is separated by polymer and color to maximize the recycle-reuse value of plastic. The job of the ZenRobotics Fast Picker is to ensure high output purity for clear PET by removing contaminants and taking out other valuable recyclable polymers such as HDPE that are returned back to the recycling loop. Thanks to its compact size, the ZenRobotics Fast Picker has been integrated into the existing sorting line despite very tight spaces at the facility.

SUP Directive: Negative consequences of strict deadlines on EU Single Market

National legislators are currently rushing into their legislative activities in the attempt of meeting the strict timeline set at EU level.

“The Commission should have realised the disruptive impact of the Single-Use Plastics (SUP) Directive on businesses and how lengthy national legislative processes can be. Those changes cannot be done overnight and the fragmentation of the EU single market is now an unavoidable scenario having severe consequences on employment and businesses losses in the EU”, said Alexandre Dangis, EuPC Managing Director.

The Single-Use Plastics Directive is a peculiar piece of European legislation that leaves considerable room for interpretation to the national legislators. Member States are developing dissimilar understandings of many pivotal concepts, which will eventually cause the impossibility to preserve the ultimate goal of the harmonization throughout the European Union.

The differences among EU Member States are substantial, both in regard to the timeline of the transposition and the content of the legislative acts themselves. Many countries already proceeded with the notification to the European Commission of the draft texts for the transposition. Among others, France decided to take some distance from the provisions of the Directive and, after gathering the feedback of many concerned stakeholders, one of the notified texts was recently sent back to the national legislator for amendment, causing further delays. Italy might be the only country to take the questionable decision of excluding bio-based plastic products from the scope of the transposition law, while in Sweden the delay seems to be an unavoidable scenario due to the extremely high number of responses that the draft text of the national law received from the stakeholders. Many countries like Romania and Bulgaria have not made yet real steps towards the transposition.

If timely provided, the long-debated Guidelines could have represented a great instrument for Member States to build together a unified framework in the context of the national transposition. However, the guidance was only published at the end of May, just one month before the deadline for transposition, causing the document to lose its very raison d’être.

“The entire world is still paying the consequences of the outbreak of the pandemic, which, in the past year, has represented the main element of focus and concern both at EU and national level. Allowing a shift of the deadline as requested by our industry at the start of the Covid-19 pandemic could have granted the EU Member States enough time to properly consider all the legislative options, work on harmonization and properly exploit the clarifications provided by the Guidelines and the other implementing acts still” according to Dangis.
Now the focus will be put on supporting national stakeholders in their battle for a fair transposition of the Directive, trying to limit, to the extent possible, the expected negative consequences of those unprecedently rushed transposition processes which is only work for lawyers and eurocrats.

SUP Directive: Negative consequences of strict deadlines on EU Single Market

National legislators are currently rushing into their legislative activities in the attempt of meeting the strict timeline set at EU level.

“The Commission should have realised the disruptive impact of the Single-Use Plastics (SUP) Directive on businesses and how lengthy national legislative processes can be. Those changes cannot be done overnight and the fragmentation of the EU single market is now an unavoidable scenario having severe consequences on employment and businesses losses in the EU”, said Alexandre Dangis, EuPC Managing Director.

The Single-Use Plastics Directive is a peculiar piece of European legislation that leaves considerable room for interpretation to the national legislators. Member States are developing dissimilar understandings of many pivotal concepts, which will eventually cause the impossibility to preserve the ultimate goal of the harmonization throughout the European Union.

The differences among EU Member States are substantial, both in regard to the timeline of the transposition and the content of the legislative acts themselves. Many countries already proceeded with the notification to the European Commission of the draft texts for the transposition. Among others, France decided to take some distance from the provisions of the Directive and, after gathering the feedback of many concerned stakeholders, one of the notified texts was recently sent back to the national legislator for amendment, causing further delays. Italy might be the only country to take the questionable decision of excluding bio-based plastic products from the scope of the transposition law, while in Sweden the delay seems to be an unavoidable scenario due to the extremely high number of responses that the draft text of the national law received from the stakeholders. Many countries like Romania and Bulgaria have not made yet real steps towards the transposition.

If timely provided, the long-debated Guidelines could have represented a great instrument for Member States to build together a unified framework in the context of the national transposition. However, the guidance was only published at the end of May, just one month before the deadline for transposition, causing the document to lose its very raison d’être.

“The entire world is still paying the consequences of the outbreak of the pandemic, which, in the past year, has represented the main element of focus and concern both at EU and national level. Allowing a shift of the deadline as requested by our industry at the start of the Covid-19 pandemic could have granted the EU Member States enough time to properly consider all the legislative options, work on harmonization and properly exploit the clarifications provided by the Guidelines and the other implementing acts still” according to Dangis.
Now the focus will be put on supporting national stakeholders in their battle for a fair transposition of the Directive, trying to limit, to the extent possible, the expected negative consequences of those unprecedently rushed transposition processes which is only work for lawyers and eurocrats.

Innovation in batch-type waste tire pyrolysis technology (part II)

In the current article (Part II) we address some characteristics and advantages of a batch reactor regarding the thermochemical reactions and their effects on the end products. We refer to the extensive scientific literature and to the findings of successful companies in the industry.

Introduction

In terms of a sustainable, environmentally sound treatment of waste tires, thermochemical conversion technologies (pyrolysis) have become increasingly important in recent years, and some of them have already proven their technical and economic maturity.

Pyrolysis is a thermochemical pathway to treat vulcanized rubber for the recovery of valuable products. It involves the decomposition of the rubber at high temperatures (400 – 900°C) in the absence of an oxygen atmosphere. The main products of pyrolysis are a solid fraction, usually raw recovered carbon black (according to ASTM D8178); a liquid fraction comprised of light oil, heavy oil, and tar; and a permanent gas fraction. [Ramirez-Canon et. al., 2018]

The thermochemical decomposition process (pyrolysis) takes place in a reactor (reaction zone). A distinction is made between batch and continuous filling and processing modes, which in turn significantly determine the reactor design.

Batch-type processes are typically characterized by a completed loading process, followed by completed processing and a subsequent unloading process. Plotting this sequence on a time axis, at different times there are different states (as material concentration in the reactor is changing with the time). In contrast to this, with continuous process designs, the material and the processing are “in flux”.

In our last article we concluded that batch-based semi-continuous tire pyrolysis systems can then exploit the advantages of “both worlds” (and even more), if

  1. the material loading and unloading is automated,
  2. the end point of complete decomposition can be permanently detected by measuring the pyrolysis gas flow (and the process duration can be continuously adjusted),
  3. the batch reactors are not exposed to downtimes and are constantly kept at the reaction temperature,
  4. and the timing of the individual processes has such short intervals that an overall view results in a continuous flow of products.

In summary, it can be stated that modern batch reactors (depending on their design) have great advantages, especially regarding a precise process control with a given inhomogeneity of the feedstock. This is a significant aspect because end-of-life tire deliveries may significantly vary depending on the manufacturer and their proprietary chemical composition. Else, the composition and yields of the products raw recovered carbon Black (raw rCB), oil and gas vary depending on the pyrolysis conditions.

Influence of the reactor model on the product yields

It is evident that the type of reactor has a key influence on oil and permanent gas yields, and on the composition and quality of recovered carbon black. The product yields depend mainly on the thermal decomposition temperature (T), the heating rate (HR) and the residence time (RT) of oil vapors and solid products in the reactor. [LEWANDOWSKI et. al., 2019]

Although the yield of raw rCB is the same in both batch type (“fixed bed”) and continuously charged (“moving bed”) reactors, provided that the feedstock was completely devolatilized in both, it can be observed that the oil and permanent gas yields are different. The oil yield is higher in a batch reactor whereas the (incondensable) permanent gas yield is higher in a moving bed reactor (e.g., Rotary kiln or Auger). The higher gas yield can be attributed to a faster heating rate and longer gas residence time (oil vapor) in a continuously charged moving bed reactor where a more severe cracking occurs. [AYLON et. al., 2008]

The higher oil yield in a batch reactor has a practical economic benefit since higher product sales can be achieved. At the same time, the (lower) yield of permanent gas with modern batch reactor designs is still sufficient to generate the necessary process heat and the waste heat from the flue gas can be used for further process steps.

Influence of the decomposition temperature and vapor residence time

Beside natural rubber (NR) the most common (synthetic) rubbers used in the manufacture of tires are cis-polybutadiene rubber (CBR), isobutylene-isoprene copolymer rubber (e.g., butyl rubber (BR)) and styrene-butadiene copolymer rubber (SBR) [KAN et. al., 2017]. The degradation (pyrolysis) takes place mainly over these rubber compounds. These processes are very interlaced and overlap with each other. The pyrolysis process of all rubbers in the tire takes place in parallel at the same time. [GONZALES et.al., 2001]

Various studies suggest that SBR decomposed mainly at higher temperatures, natural rubber (NR) at lower temperatures whilst BR can be decomposed at both higher and lower temperatures [RAMIREZ-CANON et. al., 2018].

Whereas the heating rate (HR) is influenced by the power supplied, the particle size, and thermal conductivity of the feedstock, the temperature (T) affects the types of primary thermal decomposition reactions of organic materials. Prolonging the residence time in the reactor increases the probability of secondary reactions, such as the conversion of oil and char into gas, because the molecules present in the liquid and the remaining solid body decompose to form smaller molecules that enrich the permanent gas fraction. [LEWANDOWSKI et. al., 2019]

Laboratory tests have shown that the yield of liquid increases first to a maximum value at 475 °C, and then decreases to a minimum value at 575 °C. The gas yield increases over the whole temperature range. It is apparent that a sharp optimum exists in temperature at which maximum yield of liquid was achieved probably due to strong cracking of the feedstock at this temperature. However, 475 °C seems to be the optimum temperature to obtain liquid products (oil) from thermochemical conversion of the tire feedstock by pyrolysis technology, since decomposition is complete, and the liquid yields become maximized at this temperature. [ROFIQUL ISLAM et. al., 2010]

High temperatures generally favor the production of oil (liquid fraction) where the highest amount was obtained at 550 °C. However, a further increase of the temperature leads to higher production of gas and a reduction of the liquid fraction compared to that one obtained at 550 °C. [RAMIREZ-CANON et. al., 2018]

In contrast low temperatures around 450 °C result in a high production of raw recovered carbon black (solid fraction). But the solid fraction slightly decreases with a further increase in temperature until 550 °C. At higher temperatures, the solids yield increases again [RAMIREZ-CANON et. al., 2018]. Anyway, various studies have shown that the optimal decomposition temperature for the production of raw recovered carbon black (solid fraction) is between 450 °C and 550 °C.

Also, low temperatures (plus low pressure and short vapor residence time) favor the production of limonene, benzene, toluene, and xylene (BTX) and increase their yield in the oil (TDO). Limonene and BTX are high-value primary chemicals with many noteworthy applications.

High temperatures (above 550 °C) and/or long residence times, however, lead to secondary subsequent cracking reaction of volatiles which (inter alia) promote the undesirable development of aromatic and polycyclic aromatic compounds. [cited in NKOSI et. al., 2021]

Conclusion

In contrast to the continuously charged rotary kiln and auger reactors, which are usually associated with a high heating rate and longer vapor residence time, which in turn can cause undesired secondary reactions, the slower heating rates of modern batch reactors tend to prevent secondary reactions and thus increase – through the limited gas accumulation around the char external area – the value of the recovered carbon black produced. [LOPEZ et. al., 2010; NKOSI et. al., 2021]

The complex and partially overlapping processes that take place during end-of-life tire pyrolysis and the given inhomogeneity of the feedstock (with a chemical composition that cannot be precisely determined for every delivery) underline the importance of precise process control. This, especially regarding the question of a completed devolatilization of all volatile components from the solid fraction and thus the rCB is “dry” but not “roasted” (and / or a subsequent energy-intensive “second” pass would be required).

It is therefore obviously not so much the continuous material feed, but the continuous process progress control that is important for high product quality and the necessary flexibility regarding constantly changing feedstock qualities (even if their variance may appear marginal)!

Considering the easier implementation (and other arguments mentioned), this appears to be a strong argument for a modern, batch-based, and semi-continuous process design.

Weibold Consulting