TECHNICAL FIELD

[0001] The present disclosure relates to processes for recycling end-of-life tyres and plastics.

BACKGROUND

[0002] Polymeric materials such as rubber and plastics are used ubiquitously worldwide. With rapidly growing populations and economies there has consequently been a rapid increase in waste generation and associated concerns about the world’s ecosystems. For example, the contamination of seas by polymer products is expected to cause a yearly loss of 1-5% in ecosystem services, resulting in financial losses of roughly USD 2.5 billion per year.

[0003] Using tyres as an example, the global demand for tyres is expected to be 3.2 billion units in 2022. End-of-life or scrap tyres take up space in landfills or are often illegally dumped. Landfilling requires huge capacities of space, as tyres cannot be compressed to decrease space. To reduce the space occupied by waste tyres in landfills, shredding waste tyres prior to disposal is an option, but the high operating costs make this process impractical.

[0004] The total amount of rubber recycled at its end-of-life is 3-15%. The total amount of waste rubber re-used in some way (e.g., retreading, new products, etc.) is 5-23%. The total amount of waste rubber used for energy recovery is 25-60%. The total of amount waste rubber sent to landfill or stored is 20-30% (Brown, D. Proceedings of the Recycling of Rubber Meeting', Institute of Materials: London, UK, 2008; Forrest, M.J. Recycling and Re-Use of Waste Rubber; De Gruyter: Boston, MA, USA; Berlin, Germany, 2019.).

[0005] Whilst the U.S. Tire Manufacturers Association has reported that tyres remain one of the most recycled products in the U.S., end-of-life markets are simply not keeping pace with the annual generation of scrap tyres.

[0006] End-of-life tyres and plastics can be disposed of by burning, gasification or pyrolysis. However, these processes have high carbon emissions and pose pollution risks. End-of-life tyres and plastics can also be repurposed into energy and other recycled products. However, these products are usually niche or low-quality products.

[0007] To date, none of the protocols discussed above is keeping pace with the annual generation of end-of-life rubber and plastics.

[0008] There is thus a need to provide improved processes for processing end-of-life rubber and plastics. Alternatively, or in addition, there is a need to provide recycling processes that are able to efficiently and effectively recycle end-of-life rubber and plastics products such as tyres.

SUMMARY

[0009] According to a first aspect, there is provided a system for recycling end-of-life rubber or plastics materials, the system comprising: a pyrolysis apparatus configured to subject end-of-life rubber or plastics material to a pyrolysis reaction under conditions to produce carbon black and a liquid or gaseous hydrocarbon transition feedstock; a separator for separating the liquid or gaseous mixed hydrocarbon transition feedstock from the pyrolysis reaction; a decarbonisation apparatus configured to treat the mixed hydrocarbon transition under conditions to produce hydrogen and carbon black.

[0010] According to a second aspect, there is provided a process for recycling end-of-life rubber or plastics materials, the process comprising: pyrolysing end-of-life rubber or plastics material under conditions to produce carbon black and a liquid or gaseous hydrocarbon transition feedstock; capturing the liquid or gaseous mixed hydrocarbon transition feedstock; treating the mixed hydrocarbon transition feedstock under decarbonisation conditions to produce hydrogen and carbon black.

[0011] According to a third aspect, there is provided carbon black produced by the process of the second aspect. [0012] According to a fourth aspect, there is provided hydrogen produced by the process of the second aspect.

BRIEF DESCRIPTION OF THE FIGURES

[0013] Embodiments of the present disclosure will be discussed with reference to the accompanying figures wherein:

[0014] Figure 1 is a schematic representation of a system for recycling end-of-life rubber or plastics materials according to an embodiment of the present disclosure;

[0015] Figure 2 is a schematic representation of a system for recycling end-of-life rubber or plastics materials according to another embodiment of the present disclosure;

[0016] Figure 3 is a schematic representation of a system for recycling end-of-life rubber or plastics materials according to another embodiment of the present disclosure; and

[0017] Figure 4 is a flowchart showing a process for recycling end-of-life rubber or plastics materials.

[0018] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0019] Details of terms used herein are given below for the purpose of guiding those of ordinary skill in the art in the practice of the present disclosure. The terminology in this disclosure is understood to be useful for the purpose of providing a better description of particular embodiments and should not be considered limiting.

[0020] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0021] In the context of the present disclosure, the terms “about” and “approximately” are used in combination with an amount, number, or value, then that combination describes the recited amount, number, or value alone as well as the amount, number, or value plus or minus 10% of that amount, number, or value. By way of example, the phrases “about 40%” and “approximately 40%” disclose both “40%” and “from 36% to 44%, inclusive”. [0022] The singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise. The term “comprises” means “includes.” Therefore, comprising “A” or “B” refers to including A, including B, or including both A and B.

[0023] Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described herein. In case of conflict, the present specification, including explanations of terms, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

[0024] With reference to Figure 1, disclosed herein is a system 10 for recycling end-of-life rubber or plastics materials 12. The system 10 comprises a pyrolysis apparatus 14 configured to subject the end-of-life rubber or plastics material 12 to a pyrolysis reaction under conditions to produce a first carbon black product 16 and a liquid or gaseous hydrocarbon transition feedstock 18. Such pyrolysis apparatuses 14 and processes are known in the art and may be similar to the apparatus and/or methods disclosed in any of US Patent No. US7,341,646B2, Japanese patent publication JP2014237766A, Japanese patent publication JP2014237765A, US patent publication US20070286779A1, WIPO PCT patent publication WO2010/137352A1, Japanese patent publication JP5675061B2, and/or Japanese patent publication JP6111088B2. The system 10 also comprises a separator 20 for separating the liquid or gaseous mixed hydrocarbon transition feedstock 18 from the pyrolysis reaction. The system 10 further comprises a decarbonisation apparatus 22 configured to treat the mixed hydrocarbon transition feedstock 18 under conditions to produce hydrogen 24 and a second carbon black product 26. Such decarbonisation processes are known in the art, some examples of which include disclosures in US Patent No. US 10,808,097B2, US patent publication US20190048200A1, US patent publication US20180022925A1, US patent number US11149148B2, Canadian patent publication CA2937870A1, US patent publication number US20200140691A1, European patent publication EP3331821A1, European patent publication EP3253826B1, Canadian patent publication CA3033943A1, WIPO PCT patent publication W02022076306A1, US patent publication US20190048200A1, US patent publication US20180022925A1 and their equivalents. It is further envisaged that in a decarbonisation process, the temperatures may be initially raised for the liquid by-products of the pyrolysis process in order to gasify these.

[0025] The end-of-life rubber or plastics materials 12 can be any scrap, used or end of life rubber or plastic material. For example, the end-of-life rubber or plastics materials 12 may be end of life rubber such as waste rubber, old tyres and industrial rubber products. The end-of-life rubber or plastics materials 12 can also be a mixture of rubber and plastics or a mixture of different plastics materials.

[0026] The plastic may be any suitable plastic such as polyethylene, polypropylene, polypropylene, polystyrene, polyethylene terephthalate, polycarbonate, etc. Plastics that are particularly amenable to treatment in pyrolysis apparatus 14 include high density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS). Some plastics may require conditioning prior to treatment in pyrolysis apparatus 14 include polyethylene terephthalate (PET) and polycarbonate.

[0027] The end-of-life rubber or plastics materials 12 may be used as is and fed into the pyrolysis apparatus 14. For example, whole tyres or part tyres may be fed into the pyrolysis apparatus 14. Alternatively, the end-of-life rubber or plastics materials 12 may be treated before it is fed in to the pyrolysis apparatus 14. For example, the end-of-life rubber or plastics materials 12 may be comminuted or crushed to produce a crumb, chips, shreds, particles or powder. This increases the surface area of the material and enhances the rate of the pyrolysis reaction. The end-of-life rubber or plastics materials 12 may be comminuted or crushed using any suitable mechanical cutting or grinding process. The end-of-life rubber or plastics materials 12 may be comminuted into pieces within the size range of from about 5 mm to about 30 mm.

[0028] The end-of-life rubber or plastics materials 12 may be maintained in a hopper or similar container before it is fed to the pyrolysis apparatus 14.

[0029] Optionally, the system 10 may comprise apparatus for pre-heating of the comminuted end- of-life rubber or plastics materials 12. The apparatus may use heated flue gases from the pyrolysis apparatus 14 to heat the end-of-life rubber or plastics materials 12. The apparatus may include means for monitoring temperature in the pyrolysis apparatus 14, temperature of the comminuted end-of-life rubber or plastics materials 12 and a controller for performing a pre-set control of flow rate of the gases.

[0030] Tyres are composed of various elements including rubber/elastomers (45-47%), carbon black (21.5-24%), metals (12-25%), textile (0-10%), zinc oxide (1-2%), sulfur (1%), and additives (5-7.5%). Optionally some or all of the non-rubber components may be separated from the end-of-life rubber or plastics materials 12 before it is fed in to the pyrolysis apparatus 14. For example, at least some of the steel wire may be separated magnetically from the comminuted end- of-life rubber materials 12. Alternatively, or in addition, the end-of-life rubber or plastics materials 12 may be chemically treated prior to it being fed in to the pyrolysis apparatus 14.

[0031] The pyrolysis apparatus 14 can be any suitable apparatus that subjects the end-of-life rubber or plastics materials 12 by microwave pyrolysis, thermal pyrolysis or vacuum pyrolysis. The pyrolysis apparatus may be electrically powered. Advantageously, the electrically powered pyrolysis apparatus 14 may be powered from a renewable source in order to reduce the carbon footprint. Alternatively, a thermal pyrolysis apparatus 14 may be thermally powered. Optionally, the thermal energy may be internally derived by the oxidation of a portion of the gaseous, oil or solid fuels generated in the pyrolysis apparatus 14.

[0032] The pyrolysis apparatus 14 may also use one or more catalyst and solvent to decompose the end-of-life rubber or plastics materials 12.

[0033] In certain embodiments, the pyrolysis apparatus 14 is a microwave pyrolysis apparatus. Suitable pyrolysis equipment is commercially available such as the apparatus available from supplied by Environmental Waste International (www.ewi.ca/tires-process.html), Chip Tyre Pty Ltd (chiptyre.com.au) or Klean Industries (kleanindustries.com).

[0034] In the pyrolysis apparatus 14, the end-of-life rubber or plastics material 12 is subjected to a pyrolysis reaction which results in decomposition of the material into a range of hydrocarbons that collectively provide the liquid or gaseous mixed hydrocarbon transition feedstock 18. A first carbon black product 16 is also obtained from the decomposition of the material. A solid char biproduct may also be obtained from the decomposition of the material.

[0035] The conditions used to produce the first carbon black product 16 and the hydrocarbon transition feedstock 18 in the pyrolysis apparatus 14 are preferably tuned to produce a hydrocarbon transition feedstock 18 that is suitable for decarbonisation in the decarbonisation apparatus 22. The conditions preferably minimise production of the first carbon black product 16 and force as much carbon as possible to the hydrocarbon transition feedstock 18.

[0036] The conditions used to produce the first carbon black product 16 and the hydrocarbon transition feedstock 18 in the pyrolysis apparatus 14 are preferably anaerobic. For example, the pyrolysis reaction may be carried out in the pyrolysis apparatus 14 under an inert gas atmosphere, such as a nitrogen atmosphere, and under a slight vacuum. These conditions minimise the production of carbon dioxide in the pyrolysis apparatus 14. In practice, carbon dioxide oxidises electrodes in decarbonisation apparatus 22. Also, minimising carbon dioxide production in pyrolysis apparatus 14 maximises the carryover of carbon into the hydrocarbon transition feedstock 18.

[0037] When the end-of-life rubber or plastics material 12 is rubber, such as end-of-life tyres (4), the pyrolysis produces a hydrocarbon transition feedstock 18 containing the substances identified in Table 1.

[0038] Table 1 : Substances contained in the hydrocarbon transition feedstock 18 that are suitable for decarbonisation in the decarbonisation apparatus 22 [0039] When the end-of-life rubber or plastics material 12 is plastic, the pyrolysis produces a hydrocarbon transition feedstock 18 containing the substances identified in Table 2. [0040] Table 2: Substances contained in the hydrocarbon transition feedstock 18 that are suitable for decarbonisation in the decarbonisation apparatus 22

[0041] 3.2 When end-of-life plastic 12 are used, the system 10 can produce a transition feedstock 18 containing the substances identified in Table 3 to Table 8 below.

[0042] Table 3 : A list of substances contained in the transition feedstock 18 that are suitable for decarbonisation that can be produced when the end-of-life plastic 12 is PET “1 ” (Polyethylene Terephthalate, m.p. 267 °C) and processed by the system 10.

[0043] Table 4: A list of substances contained in the transition feedstock 18 that are suitable for decarbonisation that can be produced when the end-of-life plastic 12 is HDPE “2 ” (High Density Polyethylene, m.p. 337°C) and processed by the system 10.

[0044] Table 5 : A list of substances contained in the Transition Feedstock (3) that are suitable for decarbonisation that can be produced when the end-of-life plastic 12 is PVC “3 ” (Polyvinyl Chloride, m.p., 100-260 °C) and processed by the system 10.

[0045] Table 6: A list of substances contained in the transition feedstock 18 that are suitable for decarbonisation that can be produced when the end-of-life plastic 12 is LDPE “4” (Low Density Polyethylene, m.p. 106-112 °C) and processed by the system 10.

[0046] Table 7: A list of substances contained in the transition feedstock 18 that are suitable for decarbonisation that can be produced when the end-of-life plasticl2 is PP “5” (Polypropylene, m.p. 135-165 °C) and processed by the system 10.

[0047] Table 8 : A list of substances contained in the transition feedstock 18 that are suitable for decarbonisation that can be produced when the end-of-life plastic 12 is PS “6” (Polystyrene, m.p. 240 °C) and processed by the system 10.

[0048] The first carbon black product 16 produced in the pyrolysis apparatus 14 is a low quality carbon black. The amount of carbon black produced in this step will typically be the carbon black originally present in the end-of-life rubber or plastics material 12. For example, tyres typically contain 21.5-24% carbon black and most of that may be recovered in this step.

[0049] The liquid or gaseous mixed hydrocarbon transition feedstock 18 produced in the pyrolysis apparatus 14 is separated from the pyrolysis reaction using separator 20. The separator 20 can be any device that preferably separates liquids or gases from solids, such as a cyclonic separator or other known gas-solid separator. The pyrolysis apparatus 14 may include a vacuum fan to extract any volatiles from the solids.

³ Chemeo, 2016, 'Chemical Properties of Styrene, alpha-methyl-, dimer (CAS 3910-35-8),' Chemeo, accessed online, <https://www.chemeo.com/cid/34-383-9/Styrene,%20alpha-met hyl-,%20dimer> [0050] The mixed hydrocarbon transition feedstock 18 is treated in decarbonisation apparatus 22 under conditions to produce hydrogen 24 and a second carbon black product 26.

[0051] Decarbonisation apparatus 22 may treat the mixed hydrocarbon transition feedstock 18 by any suitable thermal, thermal plasma or thermo-catalytic decarbonisation process. Suitable equipment for achieving decarbonisation is commercially available from Monolith Inc. (monolithcorp. com), Hazer Group (hazergroup.com.au), C-Zero (www.czero. energy) or Synergen Met Limited ( w w w . synergenmet.com/hydrogen-production) .

[0052] Advantageously, the decarbonisation apparatus 22 may be powered from a renewable source as a means to reduce the carbon footprint.

[0053] The mixed hydrocarbon transition feedstock 18 can be fed into decarbonisation apparatus 22 at a temperature range from 1°C to 2,000°C. At this temperature, the substances in the mixed hydrocarbon transition feedstock 18 will primarily be in a gaseous form. Molecules in the gaseous form are most desirable for decarbonisation. However, some decarbonisation technologies are able to accept both gases and liquids.

[0054] The mixed hydrocarbon transition feedstock 18 may be conditioned for decarbonisation by removing substances that are undesirable, such as carbon dioxide (CO2) and hydrogen Sulphide (H2S), by applying scrubbing equipment in conjunction with a heat exchanger.

[0055] To achieve a scale, the mixed hydrocarbon transition feedstock 18 may be supplemented with hydrocarbon gases (primarily but not limited to methane) from various sources including, but not limited to fossil fuel reserves and bio-gas.

[0056] The gaseous hydrogen 24 produced by decarbonisation of the mixed hydrocarbon transition feedstock 18 may be marketed as is, and may also be upgraded to a range of products including ammonia and urea using known processes.

[0057] The second carbon black product 26 produced by decarbonisation of the mixed hydrocarbon transition feedstock 18 may be marketed for material use.

[0058] The present disclosure also provides a process 100 for recycling end-of-life rubber or plastics materials, shown schematically in figure 4. The process 100 comprises pyrolysing end- of-life rubber or plastics material 110 under conditions to produce carbon black and a liquid or gaseous hydrocarbon transition feedstock 120. The liquid or gaseous mixed hydrocarbon transition feedstock is captured and treated under decarbonisation conditions 130 to produce hydrogen and carbon black 140. In turn the hydrogen by product may then be utilised 150 in the production of ammonia, for example for the manufacture of fertiliser. The high quality carbon black produced in the decarbonisation process is in turn utilised 160 in the production of new tyres.

[0059] The present disclosure also provides carbon black produced by the processes described herein.

[0060] The present disclosure also provides hydrogen produced by the processes described herein.

[0061] It will be evident from the foregoing that the systems and processes described herein may have one or more of the following advantages:

• the systems and processes reduce the carbon emission footprint of recycling or repurposing end-of-life rubber and end-of-life plastic;

• the systems and processes increase the recycling rate and quality of materials derived from end-of-life rubber and end-of-life plastic;

• the systems and processes reduce the need for carbon black manufacturing from virgin fossil fuel;

• the systems and processes reduce the likelihood of direct and indirect pollution from end-of-life rubber and end-of-life plastic; and

• the systems and processes may incorporate sulphur management technology when applied to end-of-life rubber.

[0062] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

[0063] It will be understood that the terms “comprise” and “include” and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0064] In some cases, a single embodiment may, for succinctness and/or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0065] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.