The Challenges for Secondary Raw Materials
Is there a circular economy for end-of-use-cycle tyres and other industrial rubber products? There are a lot of competing forces and trade-offs being made under the name of the circular economy which begins to highlight the real challenges we face in the development of a secondary raw materials industry. Although there are several different products manufactured from end-of-use-cycle tyres, such as athletic surfaces, gym flooring, rubber matting, road construction as barriers and permeable pavement, this article focuses on Tyre Derived Fuel (TDF).
Tyre-derived fuel is composed of shredded scrap tyres. Tyres may be mixed with coal or other fuels, such as wood or chemical wastes, to be burned in concrete kilns, power plants, or paper mills. A US EPA test program concluded that, with the exception of zinc emissions, potential emissions from TDF are not expected to be very much different from other conventional fossil fuels, as long as combustion occurs in a well-designed, well-operated and well-maintained combustion device.
As an advocate of materials management rather than waste management the starting point is with compounds. On average, a modern tyre on a passenger car will contain up to 25 components and as many as 12 different rubber compounds. Knowing the compounds of tyres helps the reprocessing industry to determine how the end-of-use-cycle tyre will be reprocessed and ultimately, how the material will be used in its second use-cycle.
- Rubber (natural and synthetic) 41%
- Fillers (carbon black, silica, carbon, chalk…) 30%
- Reinforcing materials (steel, polyester, rayon, nylon) 15%
- Plasticisers (oils and resins) 6%
- Chemicals for vulcanisation (sulphur, zinc oxide…) 6%
- Anti-ageing agents and other chemicals 2%
In 2023, the equivalent of 68 million passenger car tyres came off vehicles across Australia according to statistics from Tyre Stewardship Australia (TSA). An equally bigger problem are tyres from the mining industry. As of August 2024, the mining industry represented 14.3% of Australia’s GDP, the largest share of any industry sector except for services (approximately 70%). Export statistics tell a different story, resources accounted for 62.5%, services at 17.9%, agriculture at 10.2% and manufactured goods at 7.4%.
- An estimated 49% of all waste mining tyres in Australia come from Western Australia’s Pilbara region.
- That equates to about 44,000 tonnes of off-the-road (OTR) tyres requiring disposal each year.
OTR tyres can have up to fifteen different compounds. For example, solid tyres for forklifts may only contain one type of tyre compound, while an OTR tyre can have more than ten different compounds depending on the size of the tyre and the type of job it is being used. This applies to not just the tread compound of the tyre, but also under tread, belt, shoulder, and bead compounds. There are different areas of a tyre that require different compounds for the unique purpose that material is being used for. Every manufacturer has its way of developing their own rubber recipe.
What is a Sustainable Outcome for End-of-Use-Cycle Tyres?
Professor Veena Sahajwalla, Director of the Centre for Sustainable Materials Research and Technology (SMaRT) at the University of New South Wales, believes tyres are much more than waste. Professor Sahajwalla has developed technology that decarbonises steelmaking by replacing coal and coke with waste tyres. The process unlocks carbon and hydrogen from the tyres, creating a raw material ‘feedstock’ of hydrogen and solid carbon.
Australian steel manufacturer Molycop has helped to develop the new steel manufacturing process alongside the UNSW SMaRT Centre, footwear manufacturer Crawford Boots, and the Advanced Manufacturing Growth Centre (AMGC).
The new process uses waste rubber from end-of-use-cycle vehicle tyres, conveyor belts, and rubber safety boots as a substitute for carbon-heavy feedstock in the company’s Newcastle (New South Wales) furnace. This process is less emissions-intensive because while traditional feedstock contains carbon and ash and no hydrogen, rubber tyres contain carbon, roughly 8% hydrogen and a lower level of ash. Because hydrogen is a very efficient reducing agent, less carbon is emitted when the rubber burns.
Is burning tyres a sustainable or circular outcome?
The Circular Economy for End-of-Use-Cycle Tyres
The US company Lehigh Technologies has developed PolyDyne™ a ground rubber compound produced from end-of-use-cycle tyres that provides compound cost savings, lower cost compound options, reduced landfill costs and supports circular and sustainable materials use. PolyDyne™ is currently being incorporated into tyres around the world, including North America, Europe, Asia and South America. To date, over 500+ million tyres have been manufactured using Lehigh’s micronized rubber powder. Seven of the top ten tyre companies use PolyDyne™ over 40 plants in 15 countries.
The EU funded the BlackCycle project (May 2020 ~ June 2024) which brought together 13 partners from six countries. BlackCycle has an upcycling ambition, the target is to create a circular economy of end-of-life tyres (ELT) into technical applications for the tyre industry by producing highly technical second raw materials (SRMs) from ELTs. A key lever is to consider the circular economy within the tyre domain: recycle ELT into new tyres. Currently, known technologies in this domain are limited and this new research project will have the ambition to pass these roadblocks and deliver new technical raw materials relevant to tyre production or other technical products.
Rubber Production and Deforestation
The demand for natural rubber continues to rise due to its affordability, lightweight properties, and suitability for a wide range of applications. From insulating materials to tyres and shock absorbers in the automotive industry, footwear and construction sectors, including floor mats and window seals. In 2022, the natural rubber market was valued at approximately US$17 billion. Natural rubber remains indispensable across diverse sectors, driving its consumption to an estimated value of US$30 billion by the end of 2033.
To meet the growing demand for natural rubber the harvested area for natural rubber production is forecast to increase to an additional maximum of 5.1 million hectares worldwide in 2030. The area needed is expected to increase year-on-year, in line with a growth in natural rubber consumption over the same period. The lowest amount of additional harvest area needed by 2030 is expected to be 2.7 million hectares.
The European Union Deforestation Regulation (EUDR) is scheduled to commence on 30 December 2024. Under the EUDR, certain products for export to the European Union (EU) will have to meet new rules relating to the land on which they were produced. Exporters will need to ensure the land has not been subject to deforestation or forest degradation since 31 December 2020. They will need to provide clear evidence to EU operators and EU traders to support this.
Commodities targeted by the EUDR are:
It also extends to a range of relevant products derived from these commodities, such as leather, chocolate and paper.
Conclusion
The circular economy’s aim is to reduce the use of primary raw materials. This goal is achieved through product life extension and by maintaining the value of materials through the development of a secondary raw materials industry. The website WasteInitiatives.com.au writes, “In pursuing a cleaner environment and a regenerative, circular economy, the recycling and reuse of materials play a vital role. One such material that has gained significant attention is scrap tyres. These discarded tyres can pose environmental hazards and occupy valuable landfill space if not properly managed.
However, innovative technologies, such as Tyre Derived Fuel (TDF), provide a sustainable solution to address these challenges…”
A few Australian companies are exporting end-of-use-cycle tyres into Asia where some of it is also used as TDF. Tyre Stewardship Australia (TSA) provides information on their Foreign End Market Verification (FEM Verification) program developed by TSA in partnership with Intertek, a Total Quality Assurance provider to industries worldwide.
The FEM Verification program claims it is a leading initiative assisting to deliver supply chain transparency and improvement opportunities in areas such as Environment, Health & Safety and Modern Slavery.
TSA states they work with local businesses exporting tyre-derived material, tyre seconds and casings to understand and mitigate environmental, social and occupational health and safety (OH&S) risks by having their overseas destinations assessed against in-country regulations and basic environment, health and safety standards. Providing greater transparency and confidence in the entire supply chain for end-of-life tyres.
There is no doubt this is a great initiative except in-country regulations may not be as robust as we all would like. More to the point, there is a balancing act between carbon emissions, the huge volume of end-of-use-cycle tyres, deforestation and resource management. To only focus on one, such as carbon emissions, the current justification and business model for TDF from tyre recyclers and waste management companies misses the bigger picture. Nor does it develop real markets for a genuine secondary raw materials industry, within Australia and with business partners in the Asian region.
The practical application of the circular economy is complex and requires stakeholders all working together. Companies will need to look beyond short-term profits of TDF for domestic and regional markets because at the moment there is a lot of money being left on the table. It is this money that will determine the longevity of many reprocessors wherever they may be geographically located.
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Ms Adrienna Zsakay is the Founder and CEO of Circular Economy Asia Inc., and this article represents her opinions on the circular economy. Circular World Pick of the Week is brought to you by Circular World™ Media — a brand owned by Circular Economy Asia Inc.
For all the best content, join one of the fastest-growing circular economy groups on LinkedIn — Circular Economy Asia.
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Tyre Derived Fuel — Wikipedia
‘Tyre mixture — What’s in your tyres?’ published by Continental
‘Australia produces millions of used tyres a year but many still go to landfills’ by Norman Hermant and Lucy Kent, published by the ABC, 13 April 2024.
‘Composition of the Australian EconomySnapshot’ published by the Reserve Bank of Australia, 07 August 2024.
‘Growing push to recycle the Pilbara’s 44,000 tonnes of mining tyre waste locally’ by Rosemary Murphy, published by the ABC, 21 June 2024
‘How are OTR tyres manufactured and what are tyre compounds?’ by Maxam, 22 April 2024
‘Numerical Estimation of the Uneven Wear of Passenger Car Tires’ by Sang Wook Lee, Kyoung Moon Jeong*, Kee Woon Kim, Jang Hyeon Kim from the R&D Center, Kumho Tire Co. Inc., Yongin, South Korea, published by World Journal of Engineering and Technology, 2018.
‘Rubber Reimagined: The Tireless Potential of Recycled Tyres’ by Hayley Webb, published by the Australian Circular Economy Hub, 16 April 2024
‘Greener steelmaking cuts carbon using thousands of old car tyres’ by Amalyah Hart & Joshua S. Hill, published by Renew Economy, 06 April 2023
Tires by Lehigh Technologies
‘For The Circular Economy Of Tyre Domain: Recycling End Of Life Tyres Into Secondary Raw Materials For Tyres And Other Product Applications’ — CORDIS EU Research
‘Natural rubber market forecast at $30 billion by 2033’ published by RubberWorld, 08 May 2024
‘Minimum and maximum additional harvested area for natural rubber consumption between 2020 and 2030 worldwide’ from Statista, published 07 August 2024
‘European Union Deforestation Regulation’ published by the Department of Agriculture, Fisheries and Forestry, Australian Government.
‘Tyre Derived Fuel: A Sustainable Solution for Energy Production’ published by www.wasteinitiatives.com.au
‘FEM Verification — Foreign End Market Verification’ by Tyre Stewardship Australia
Originally published at https://www.linkedin.com.
