Disruptions to Carbon Black supply chains, rising costs of the fossil fuels used to produce Carbon Black, sustainability regulations, and stakeholder pressure have concerned industry leaders about the future of Carbon Black.

Luckily, more circular options are on the market, with similar properties to Carbon Black. Although they’re not directly replacing Carbon Black, these sustainable options have applications in many industries.

This article will teach you about the many recovered Carbon Black uses as a sustainable opportunity, especially as a feedstock for paints and inks.

What is recovered Carbon Black?

Recovered Carbon Black (rCB) is a solid residue from end-of-life tire (ELT) pyrolysis. Though rCB can be produced from various rubber waste, the billions of ELTs discarded annually provide a plentiful feedstock that would otherwise be treated as waste and end up in landfills.

Char is one of the tire pyrolysis products that is processed, milled, and pelletised to yield rCB. Industries manufacturing tires, inks, paints, coatings, and rubber that usually use virgin Carbon Blacks (vCBs) are opting for rCB. These industries find rCB is a sustainable choice capable of matching vCB properties and can help to overcome vCB supply bottlenecks and high costs. It’s also a more planet-conscious option that can meet consumer and industry demands for green products.

For example, the automotive industry is sourcing products made from recycled raw materials to make circular cars. Tire manufacturers incorporating rCBs into their tires can ensure that new cars are more sustainable and have a lower carbon footprint.

Similarly, the paints and coatings industries are adopting green chemistry and emphasising resource conservation by using products from alternate feedstocks instead of fossil fuels to minimise carbon emissions. Currently, 2 per cent of global fossil fuels are used to make ingredients for the paints and coatings industry.

Depletion of fossil fuels and concern over carbon emissions are driving the paints, inks, and coatings industries to look for sustainable opportunities. Instead of fossil fuels, rCB production uses ELTs as feedstock in pyrolysis, making rCB a circular option for vCBs made from fossil fuels.  

Properties: recovered Carbon Black vs virgin Carbon Black

Despite its environmental and cost advantages, rCB is not a 1:1 replacement for any particular vCB grade.

rCB is a new, unique grade with its own properties. The American Society for Testing and Materials (ASTM) International workgroup 36, set up in 2017, is still developing quality standards for rCB. The properties of rCB include a mix of passenger and truck ELTs used in pyrolysis. Recovered Carbon black’s in-rubber properties are close to the vCB grades from N550 to N772, with N650 and N660 as the closest matches, found in significant quantities in tires of all vehicles. In coatings or plastics, rCB can substitute popular grades like N220 and N330.

However, minor amounts of high reinforcing vCB grades in tire components will also be part of rCB. Moreover, the chemicals and additives in waste tires will also make their way into rCB, affecting its properties.

The circular option: Recovered Carbon Black

rCB is a sustainable Carbon Black option because of its small carbon footprint and circularity.Contec’s rCB manufacturing process ensures 80 per cent less or 2 tonnes fewer carbon emissions per tonne of the product than vCB production. Whereas producing vCB requires 2 tonnes of sulphur-rich fossil fuels, 1 tonne of rCB can be made from just three ELTs. 

The rCB’s low carbon footprint and circularity help industries comply with the environmental standards industries must now meet.

Tire producers can solve their waste problems and meet requirements set by the EU End-of-life Vehicles Directive using pyrolytic products.

The paints, inks, and coatings industries will find rCB valuable in reducing emissions as required by the Industrial Emissions Directive 2 2010/75/EU (IED) and its 2022 revisions covering chemicals production. The Directive regulates pollutant emissions (including greenhouse gases) and stipulates the use of Best Available Techniques to choose raw materials. The 2022 Commission to revise the IED supports improving resource use to build a low-carbon, clean, and circular economy.

Moreover, rCB’s low volatile organic carbon content and water-based formulations help the paints, inks, and coatings industries comply with REACH Regulation (EC 1907/2006) controlling the production and use of chemicals.

How is recovered Carbon Black made?

Around 20 to 30 types of pyrolysis processes exist, but not all are created equal. Conventional pyrolysis systems can’t guarantee consistency in the quality of rCB. Contec has improved the pyrolysis process with several innovations to make rCB of consistent quality.

What is pyrolysis? It’s a thermo-chemical process, and the technique is several decades old. While it has been used to recycle tire waste to recover materials for many years, market interest in the technology is new.

The tire rubber is separated from other components like steel, wires, and fabrics as part of the process and sent into a reactor. Contec uses its novel Molten technology to heat the shredded tires to temperatures up to 510°C in an oxygen-free atmosphere to decompose the complex polymers in tires into simpler components. The pyrolytic products of commercial interest are recovered gas, oil, Carbon Black, and steel.

What are common Carbon Black grades?

Carbon Black is a synthetic material made of 98 per cent carbon. Petroleum oil, gas, and coal tar are the common raw ingredients used to produce vCB through burning in reactors at very high temperatures to vaporise the carbon. After cooling, a paracrystalline spherical powder is made.

Different manufacturing processes and feedstocks produce varying particle sizes, surface area, and aggregate structure, which define the properties of the vCB. This means there are many grades of Carbon Black.

Most vCB grades stabilise and strengthen rubber products, but some also act as pigments:

• Grades with smaller particles, such as N110, N220, and N234, have high reinforcing, abrasion resistance, and tear strength. These grades are used as reinforcing filler materials to make rubber elastomers that form tire treads.
• Medium to high reinforcing grades like N330, N339, and N550 are found in tire treads, inner liners, carcasses, sidewalls, hoses, and extruded goods.
• Medium reinforcing vCB grades like N660 and N770 have low heat build-up and prevent tire deformation. They’re suitable for tire sidewalls, inner liners, and sealing rings. Other applications include hoses, extruded goods, cable jackets, footwear, floor mats, and mechanical goods.
• Low reinforcing vCBs like N990 have high loading capacity and elongation and are suitable for tire inner liners and belts, footwear, belts, hoses, mechanical goods, and wire insulation.

What are the uses of Carbon Black?

The tire industry consumes around 70 per cent of Carbon Black. Manufacturing other rubber products consumes around 20 per cent, with the remaining 10 per cent used for non-rubber applications. Carbon Black is used in many industries due to its potential uses as fillers, pigments, or UV protectants. 

1. Fillers

Tire manufacturing uses most vCB grades as fillers to stabilise and strengthen rubber products, such as tire treads, sidewalls, tubes, belts, and carcasses. The cumulative effect of vCBs makes tires safer, longer lasting, and more durable for driving.

The vCBs comprise 21.5 per cent and 22 per cent of passenger and truck tires, respectively. The rCB’s properties make it a suitable replacement for several of these vCB fillers, reducing the carbon footprint significantly.

2. Pigments and For UV-Protection

Several vCB grades produce a wide range of pigments with good tinting, conductivity, and dispersibility properties, providing ultraviolet (UV) protection.

• The tire industry uses Carbon Black to protect tires from the harmful effects of UV light and ozone to extend tire lifespan. 
• Inks, coatings, and paint manufacturers use Carbon Black to enhance the undertone and colour in many ink types, including toners for laser printers and screen inks. Coatings benefit from the Carbon Black’s high jetness, UV protection, and conductivity. High-performance coatings for aerospace, marine, wood, industrial, and decorative applications rely on Carbon Blacks.
• Plastic manufacturers add Carbon Black to industrial bags, refuse sacks, and household containers. The Carbon Black adds colour and provides UV protection to the plastic polymers making them thermal resistant. These properties are also essential for power cable insulations.

The use of fossil fuels to provide feedstock and energy for the manufacture of vCBs has increasingly become an image and compliance issue in all industries. rCB is a sustainable option to vCB for several of the above applications. Adding 10 to 30 per cent of rCB will often maintain the properties while reducing the negative environmental impact.

Common recovered circular products from ELTs

Each of these four recovered products has a place in the circular economy.

1. Recovered Carbon Black

Contec’s ConBlack® is a sustainable Carbon Black option, which can replace up to 30 per cent of semi-reinforcing vCBs, such as N550 and N660, to make new tires. ConBlack® can make inner liners, sidewalls, sealing rings, heavy-duty conveyors, transmission belts, and hoses. Adding up to 100 per cent of rCB can secure UV protection and produce non-tire items like rubber sheeting, roofing, cables, geomembranes, pigments, paints, inks, coatings, and plastic items.

2. Recovered gas

Gas is one of the first products formed in pyrolysis. Some condense into liquids during cooling, but the rest remains as gas, rich in hydrocarbons such as methane, butadiene, and butadiene. Contec has achieved self-sufficiency by using its recovered gas to heat the Szczecin plant.

3. Recovered Oil

Contec’s ConPyro® is the oil produced after refining and can equal virgin fossil fuels in quality. Sulphur and aromatic hydrocarbon-rich end-of-life tires derived pyrolysis oil (TDO) can replace fossil-based oil as feedstocks to produce high-reinforcing vCBs. These vCBs can further increase the proportion of recovered materials in tires.

4. Recovered steel

Contec’s ConWire® is retrieved before and after pyrolysis and can also be used again to produce new tires without losing quality. The tire, paints, coatings, ink, and plastic industries are considering various options, including biological materials and recycled products, as circular options to produce more sustainable Carbon Black options.

Manufacturers should consider using recovered Carbon Black

Recovered Carbon Black’s importance as a sustainable, circular raw material for several industries is growing.

In the tire manufacturing industry, rCB can offer a greener option. In the inks and paints industries, higher concentrations of rCB will be required to get the same pigment opacity levels as with vCB. However, the environmental benefits of rCB are considerable and outweigh the issues associated with making the switch.

Contec’s ConBlack® uses ELTs as feedstock and is asustainable and circular Carbon Black option to vCB because of its various proven uses and applications in several industries, from tire and rubber to paints, coatings, and inks. Get in touch to learn more about our sustainable solutions.

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Environmental protection is becoming an important concern in manufacturing.

However, manufacturers do not have all the necessary viable technology to reach their Net Zero goals and help limit global warming to 1.5˚C. Therefore, R&D investments are being made to find circular solutions limiting carbon footprints, waste generation, and natural resource use in manufacturing.

This article will show how investing in R&D supports the circular model adoption — and how Contec is part of the story.

How to adopt the circular economy through R&D?

Knowing how to transition from a linear to a circular manufacturing business model can be challenging. Breaking down the process into small steps can make it easier to implement viable solutions. At Contec, we recommend breaking down this process into two steps.

Step 1: Determine carbon footprint and environmental impact

Manufacturers trying to reduce their environmental impact can start by establishing their current carbon emissions.

To do this, it’s important to calculate not only scope 1 and 2 emissions for each product but also scope 3 emissions: 

• Scope 1 and 2 emissions come from company activities and energy sources.
• Scope 3 emissions cover a product’s entire value chain. These include emissions from manufacturing, processing, services, transporting raw materials, product packaging, transport, and media.

In some EU countries, it is also a requirement for companies to document data collection and testing for verification and transparency.

Step 2: Introduce a framework and standard for managing environmental impact

Companies should introduce a system for environmental management, like ISO 14001, if they don’t have one already.

They can incorporate their carbon footprint data into the system, which provides the structure needed for environmental improvements. These include formulating an environmental policy, planning, implementation, checking, and management review.

Most companies easily control Scope 1 and 2 emissions by replacing conventional energy with renewable sources. However, the complexities of Scope 3 emissions, accrued from other companies’ activities, make it harder to control them. For example, most emissions in tire manufacturing come from raw materials, like rubber and virgin Carbon Black (vCB), produced from fossil fuel-based feedstocks.

What other activities can R&D support?

R&D can help reduce the Scope 3 emissions of an entire value chain by providing innovative technological and material solutions.

Circular solutions such as recycling reduce natural resource use, associated carbon emissions, and the environmental impact of producing ingredients by making secondary raw materials from waste. It reduces waste landfilling and soil and water pollution. Moreover, circularity emphasises incorporating old material into new products, keeping it in circulation.

For example, tire manufacturers can get high-quality recovered Carbon Black (rCB) from pyrolysis using Molten technology. Molten allows for uniform and regulated heating of tire wastes to produce rCB of high and consistent quality. This rCB can replace 20 per cent of medium-grade vCB. Molten technology uses less energy to produce secondary raw materials, reducing production emissions.  

rCB’s carbon footprint is only 20 per cent of vCB’s. Tire manufacturers can use rCB in a tire-to-tire business model to diminish Scope 3 emissions. Thus, an innovation like Contec’s Molten technology integrated into an old process like pyrolysis can become a game changer for the entire tire industry.

Evolving the R&D at Contec

Every technology is the result of detailed research. However, a manufacturing operation can’t be changed before its influence on the process and product quality is identified. For this, it’s necessary to have standards to establish product quality and correlate new applications with product parameters.

These standards are created by more investment in R&D.

Contec’s pyrolysis process is rooted in R&D. Molten technology was incorporated into tire pyrolysis during laboratory testing and was found to improve the efficiency and safety of tire pyrolysis for people and the environment.

Next, Contec aimed to scale up the innovation and upgrade the tire pyrolysis plant to achieve nominal capacity. Due to an absence of ready-made technological solutions, Contec built its own laboratory facilities and tested the effect of every technology process change on product quality. Complete control over the research process and cooperation with technical universities make Contec’s R&D process unique.

Since there were no existing rCB quality standards, Contec joined the ASTM Committee D36 to contribute to formulating quality standards and testing methods for rCB. The company leverages its knowledge over years of R&D to improve product quality.

The Circular Economy is not possible without R&D

R&D can enable the development of environmentally friendly technologies for the circular economy by supporting the environmental impact verification of new recycled products.

A company with its R&D laboratory can shorten the validation process through monitoring and rapid course corrections. The flexibility to customise tests for specific needs helps to create products suited for market needs and gives a company a competitive edge. Cooperation with research institutions increases access to scientific expertise and improves fund-raising possibilities. Follow our Linkedin Page to learn how the latest R&D advancements.

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As manufacturers move toward the circular economy, they’re increasing the use of recycled materials.

In the tire and automotive industry, one of the solutions is to extract raw materials from recycled tires to produce new tires with a higher percentage of recycled materials.

Contec is one of the supporters of this movement toward circularity, supplying raw materials from recycled tires and allowing manufacturers to keep resources circulating within the industry.

However, tires are complex products, and to fully understand how a tire-to-tire circular model can function properly, it’s essential to know the composition and components of the tires.   

Let’s start with understanding the composition of tires: what are they made of?

What are tires made of?

Tires are complex structures made of rubber, steel, and fabric components. Rubber is the primary material in any tire, and four main types of rubber are used in various tire components (Grammeli).

The primary source of natural rubber is Hevea trees (or rubber trees), whose latex is about 40 per cent rubber. The rubber is extracted by coagulating the latex with formic acid. Natural rubber is self-reinforcing and has high mechanical strength and medium elasticity but has low viscosity and other disadvantages.

Natural rubber needs further treatments before it can be used in tire manufacturing, such as vulcanisation, mixing with Carbon Black fillers, and other processes (Deng).

Due to the high cost and scarcity of natural rubber, synthetic rubber polymers produced from fossil-fuel-based hydrocarbons are also used (Deng). All synthetic rubbers are highly elastic and have good wear resistance, but variations in heat generation and hysteretic loss exist. There are four main types of synthetic rubber:

• Styrene Butadiene Rubber
• Polybutadiene Rubber
• Isobutylene-isoprene Rubber
• Isobutylene-isoprene Halogenated Rubber

In tire manufacturing, synthetic and natural rubber are cut and mixed in fixed ratios with other ingredients.

Different recipes or precise mixes of materials produce tires with unique properties suitable for diverse vehicles. Moreover, tire rubber composition can differ based on national or regional regulations (Grammelis), as shown in Table 1.

Composition of tires: beyond rubber

Even though rubber is the primary component in any tire, it’s essential to recognise that tires are complex products, and their composition extends to many other materials that vary according to their use and country of origin.

Besides rubber, the different materials in a tire are steel, textiles, fillers, and chemical additives required for structure, strength, longevity, and durability, as we can see in the table below:

Table 1: The composition of tires from different regions will vary. Materials are listed according to the percentage of the total tire weight. (Credits: Progress in used tyres management in the European Union: A review)

Let’s look at each tire component in more detail:

• Rubber (natural and synthetic) comprises 41-45 per cent of tire materials and has structural and strain functions. Rubber determines tread tensile and tear strength, elasticity, and elongation. Truck tires have more natural rubber, and car tires have more synthetic rubber. Trucks carry heavy loads and travel intensively, so the tires are subject to wear and tear. Natural rubber’s abrasion properties are superior to synthetic rubber, so more natural rubber is used for trucks. A higher proportion of synthetic rubber is enough for less wear and tear in car tires due to lower load and mileage. 
• Fillers make up nearly 30 per cent of tire materials. Fillers such as Carbon Black, silica, carbon, and chalk, among others, are reinforcing materials. Different fillers provide varying tire strength, wear resistance, tear resistance, rolling resistance, puncture resistance, etc.
• Steel makes up 13-25 per cent of tires, and as part of belts, beads, and plies act as a structural skeleton.
• Textiles (polyester, rayon, nylon) as fabric cords comprise around 5-15 per cent of tires and provide structure and reinforcement.
• Antioxidants, antiozonants, plasticisers, and curing chemicals comprise the remainder. The substances and percentage of these minor ingredients depend on each manufacturer.

Antioxidants like phenols and secondary naphthylamines protect against the effects of temperature and oxygen, and antiozonants shield tires against ozone. Curing chemicals like sulphur, zinc, lead, magnesium, and cadmium oxide are used for vulcanisation. Plasticisers, such as oils and resins, are added to the rubber mixture to reduce friction in the tire.

Differences in tire composition will affect the nature of secondary material recovered after recycling.

Tire recyclers like Contec have a strict truck-to-passenger-tires ratio to maintain consistency in their product profile and characteristics of products like medium-grade recovered Carbon Black (rCB). However, it’s still challenging to standardise rCB since the tires produced in different regions have varying quality and properties due to regional tire composition variations.

Contec’s involvement with ASTM International is important to developing industry rCB standards and industry applications. Learn more about our involvement in ASTM.

What are the main parts of a tire?

The main parts of a tire are the bead, bead filler, inner liner, carcass, sidewall, belts, and tread—you can see it in detail in the image below.

Bear in mind that, depending on the type of tire, there can be more components.

Figure 1: Tire structure. (Credits: What is in a Tire)

The various components used in making a tire are also crucial for material recovery. Several materials can go into making a single component depending on its function. Let’s discuss some components common to all tires below:

• Bead has steel cord in rubber bundles to secure the tire to the wheel rim and prevent wear and tear by rubbing against the edge.
• Bead Filler is a synthetic rubber component wrapped on the top and around the bead and between body plies to tune the ride.
• Innerliner is made of butyl rubber and is necessary to maintain inflation pressure.
• Carcass or body ply is made of textile, fiberglass, and aramid cords to retain tire shape and prevent the tire from bursting during inflation.
• Sidewall is made of natural rubber, protects the carcass, and can withstand bending and aging.
• Belts are composed of steel cords encased in rubber. Belts prevent carcass damage, stabilise the tread, and reduce rolling resistance.
• Tread and tread patterns can have synthetic or natural rubber, depending on their use. It’s the part that comes in contact with the road and provides grip and abrasion resistance.

The cross-linked nature of rubber structures with other materials like fabrics or steel makes recycling challenging, as the different components and materials must be separated before processing.

How are tires manufactured?

Tire manufacturing is a complex process. Each tire manufacturer follows unique and proven procedures, from raw materials selection to quality management.

There are five main stages in tire manufacturing, which, according to Weyessenhoff, are as follows:

1. Sourcing good quality material: The first step in tire manufacturing. Choosing reliable and standardised recycled secondary materials allows manufacturers to make tires circular. Manufacturers can get recovered medium-grade Carbon Black, recovered steel, and feedstocks to produce fine-grade virgin Carbon Black. They can also source carbon materials and chemical additives from other recycled biological materials. Choosing materials depends on their properties and interactions with each other because the end goal is to produce a strong and stable tire. The mixed chemical composition makes tires resistant to decomposition by chemicals or high temperatures during recycling.
2. Manufacturing components: A step that requires mixing different materials to produce various tire components. For example, steel cords and rubber for beads, etc.
3. Tire assembly: This is the stage where the components of prepared belts are wound and glued together. The end-product of this confectioning stage is called a “green tire.”
4. Vulcanisation: This step completes the process and gives the tires their final shape, including the tread and its patterns. Since the EU stipulates that the minimum tread groove is at 1.6 mm, some manufacturers add a tread depth indicator: 3 mm for summer tires and 4 mm for winter tires.
5. Quality control: Tires must pass quality tests to meet stringent safety standards (UNECE, SAE). Improper quality control during manufacturing can produce hidden defects in materials and tires. Most of these tend to occur at the interface of different materials and can be at the shoulder, internal, external, side, or tread. Quality checks during manufacturing are vital to reducing user risks and financial burdens on customers and producers.

Other questions on how a tire is made

Here are answers to three FAQs for a quick and brief understanding of the multifaceted tire manufacturing process.

Where does rubber come from for tires?

The latex of a tropical tree, Hevea brasiliensis, also known as the “rubber tree”, is the source of natural rubber used in tires.

Around 90 per cent is obtained from Asian plantations. The tire industry is the largest consumer of natural rubber, using 76 per cent of the annual rubber production. The rubber tree is currently the only commercial source of natural rubber, though efforts are being made to identify other easily renewable crops or wildflowers like dandelions to produce rubber.

The four types of synthetic rubber made from hydrocarbons derived from petroleum products are mixed with natural rubber to make tires.

What is used to make tires?

Tires are made of several materials, including natural rubber, synthetic rubber, steel, textiles (rayon, polyester, aramid, and nylon), fillers (carbon black, silica from sand, carbon), chemicals including hazardous compounds like lead and cadmium oxide, and fossil fuels as feedstock for producing many of the synthetic materials.

Are tires made of natural rubber?

Tires are made of natural rubber.

Aviation tires are made entirely of natural rubber as they withstand abrasion better than synthetic rubber. For the same reason, trucks and heavy vehicles also have more natural rubber in their tires. Passengers or light vehicles have more synthetic rubber. Due to the scarcity of natural rubber, synthetic rubber use is high, making up around 60 per cent of tire rubber, while natural rubber makes up about 40 per cent.

Adding recycled materials to tire composition

Manufacturers want to maximise circularity in tires. Therefore, tire manufacturing, especially the sourcing and assembly stages, is undergoing a paradigm shift to fit a circular economy.

Besides recycling and sourcing bio-based renewable materials for significant tire components, manufacturers are also rethinking tire design to make disassembly, material separation, and recycling easier to reduce tire waste.

Contec has one of the few tire pyrolysis plants where they recover 85 per cent of the material in tires and 15 per cent of energy to tackle the growing end-of-life tire waste problem. Contec is promoting tire-to-tire production by providing manufacturers with rCB, recovered steel, and feedstocks to realise manufacturers’ vision.

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Our funding round now reaches EUR 15 million — one of 2023’s largest Clean Tech investments in Europe.

The largest Polish manufacturer of steel roofing and facades – Pruszyński – has contributed an additional EUR 5 million to the funds already provided by VINCI and the Warsaw Equity Group. These two entities had initially invested EUR 10 million in Contec back in March 2023.  

The investment will be used to triple the capacity of Contec’s current facility in Szczecin, Poland, and to position the company for the construction of several new commercial plants across Europe. This will support Contec’s mission to accelerate the transformation of the manufacturing industry toward carbon neutrality. 

For many years, we have been supporting the efforts of the manufacturing sector to promote environmental sustainability and circularity. Contec’s circular products significantly reduce the carbon footprint by more than five times compared to traditional fossil fuel-based raw materials. That’s why there is a great deal of interest in Recovered Carbon Black for the tire, manufactured rubber goods, plastics, and pigment industries. – Krzysztof Wróblewski, CEO of Contec. 

Thank you to our investors and the entire team for making this milestone possible!

To read the full press release, please download it as a PDF .

For media inquiries, please reach out to Anna Goławska <a.golawska@contec.tech>.

We’re so proud and delighted to announce that we have won the award for ‘investment efficiency.’

Waste Management and Recycling Cluster thank you for recognizing Contec’s efforts in development and growth.

We’re happy that an independent organization has noticed our activities. It’s a clear message from the Cluster’s experts that our work is necessary.

Moreover, it serves as motivation for us to do more and not slow down. 

Waste Management and Recycling Cluster

Waste Management and Recycling Cluster (KGOIR), National Key Cluster (Klaster Gospodarki Odpadowej i Recyklingu) is a modern, innovative organization of significant importance to the Polish economy and high international competitiveness, with an established position in the country and in Europe. It belongs to the elite group of 19 Polish national key clusters certified by the Ministry of Development and Technology of the Republic of Poland, described as the most effective instruments of development policy at the national and regional level. KGOIR brings together entrepreneurs from the broadly defined area of green economy, oriented towards the closed cycle economy, dealing with, among others, waste management, recycling, recovery, creating technologies and equipment, offering pro-environmental solutions and services, as well as key Polish scientific units operating in the field of research and development and waste and packaging industry.

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Tire pyrolysis oil is the most abundant product from recycling end-of-life tires with pyrolysis.

As a circular product, its properties allow it to be used as an eco-friendly alternative to several industrial manufacturing commodities. This article will conduct a tire pyrolysis oil analysis, review the properties, and shed more light on this valuable product.

What is Tire Pyrolysis Oil?

Tire pyrolysis oil (TPO) is the liquid fraction produced by the pyrolysis of end-of-life tires (ELTs). According to Martinez 2023, TPO can make up between 40 and 50 per cent by weight of the pyrolytic products depending on the process and temperature.

TPO is a thick, viscous dark brown or black liquid that can be semi-solid in cooler temperatures. It’s a complex mixture of hydrocarbon families with varying carbon numbers of C5 – C50. These consist of 49.54 per cent aliphatic compounds and 16.65 per cent aromatic compounds, like xylene, etc. The hydrocarbons have a wide range of boiling points from 70 ºC to 450 ºC (Pilusa 2013).

TPO composition will depend on tire types, pyrolysis technology, and conditions. However, the average TPO composition (Pilusa et al., 2013) is as follows:

• Carbon: 83 per cent by weight
• Hydrogen: 6.6 per cent by weight
• Oxygen: 8.6 per cent by weight
• Nitrogen: 0.3 per cent by weight
• Sulphur: 1 per cent by weight

The various components of TPO will influence the oil’s physical and chemical properties and behaviour (Jammel 2018). 

Let’s look at some of these properties more closely.

What are the properties of tire pyrolysis oil?

Other tire pyrolysis oil analyses have found that it has critical properties and characteristics similar to some fossil fuels, allowing it to be used as an eco-friendly alternative.

However, TPO does have disadvantages, such as a higher sulphur content and a lower flash point than fossil fuels. To determine whether TPO is an appropriate alternative feedstock instead of fossil-based petroleum products for producing chemicals or use as fuel, its viscosity, flash point, calorific values, and corrosivity must be analysed.

1. Viscosity

Viscosity refers to how easily oil can flow. The viscosity of oil changes with temperature and pressure: oil becomes thinner as the temperature rises and its viscosity decreases. At 40oC, TPO from ELTs has medium viscosity and is 10 centistokes (cSt) at 40oC, whereas fossil–based diesel, which TPO could replace, has a viscosity of 2.58 cSt at 40oC (cSt) (Pilusa 2013). 

2. Density

Viscosity is connected to density, which is the relation of the weight of a substance with its volume.

At higher temperatures, oil’s density decreases. TPO from ELTs has a high energy density of 920 kg/m3@15oC. In comparison, petrol and diesel have a density of 740 and 822 kg/m3@15oC, respectively (Pilusa 2013).

3. Calorific value

The calorific value indicates the energy or heat a substance produces when completely burnt.

A high calorific value indicates a substance will be suitable as a fuel. TPO’s Gross Calorific Value is 41-44  MJ/Kg, that is, burning one kilo of it produces 41-44 megajoules of energy. In comparison, the Gross Calorific Value of diesel and petrol are 43.8 and 46.0 MJ/kg, respectively, according to Pilusa.

4. Flash point

TPO, like other fossil fuels, produces vapours.

The flashpoint of oil is the temperature at which its vapour will burn when a small flame is applied. When there is little vapour and more air, there is no combustion. When the mix of air and vapour is correct, even a small spark can cause it to burn. The pressure created from burning has produced violent explosions that can destroy storage tanks and lead to oil spills and major fires. TPO has a low flashpoint below 65°C, which is one of its disadvantages (Pilusa 2013).

5. Corrosivity

Like other crude oils, TPO is corrosive due to contaminants, like a high content of oxygen and acids.

Corrosivity in oils can affect metal pipes and storage tanks. Raw TPO can be very corrosive to metals like steel and other alloys with low chromium content. Containers at 50°C develop cracks when TPO is stored for a few hundred hours (Keiser 2011).

Why is recovered Tire Pyrolysis Oil important?

Industries are looking to increase the use of secondary products in their manufacturing processes to improve circularity. TPO is a circular and sustainable product whose range of potential applications positions it as a valuable secondary raw material.

The high carbon content of TPO makes it an interesting raw material for producing high-value carbon products. TPO is also called bunker oil or black liquor because of its composition and properties that are similar to petroleum products. It could be used in place of diesel for internal combustion engines, after distillation and removing undesirable chemicals like sulphur and nitrogen using existing refinery facilities.

Moreover, heavy aromatic compounds make TPO suitable for producing carbon black (CB) by replacing fossil fuel feedstocks, which make up 60 per cent of the manufacturing costs of CB (Martinez et al., 2023). Xylene in TPO also has several applications in the chemical industry.

It’s possible to increase the value TPO can bring to industries by introducing standards and regulations for the tire pyrolysis industry. Creating demand will also stabilise supply and prices to reduce raw material bottlenecks.

Conventional ELT recycled products like rubber crumbs have reached market saturation. TPO’s high value and wide range of applications in the circular economy can also make pyrolysis upcycling of ELTs profitable, more sustainable, and attractive globally. Though ELT recycling is high in the EU, it is very low in several regions worldwide.

Environmental reasons

The environmental benefits of TPO are another reason to consider using it instead of conventional fuels and feedstocks.

Pyrolysis, a thermo-chemical process, is the most environmentally friendly method of recycling ELTs. The process produces little or no pollutants, has a low carbon footprint, and can be made operationally safe. TPO’s carbon footprint as fuel is competitive compared to biofuels (Martinez et al., 2023).

Contec’s TPO

Contec’s protected and innovative tire pyrolysis process has integrated design and engineering features to make the process safe for its staff and the environment.

The company has measured its process’s carbon emissions, and ConPyro, Contec’s TPO, has a low carbon footprint of only 399.75 kg CO2e/1t.

Contec has designed and operates one of Europe’s few tire pyrolysis plants to solve the ELT problem and produce circular products for tire manufacturing, plastics, and other industries. Promoting tire pyrolysis oil uses helps to support the circular economy and sustainability goals. Find out more about Contec’s circular TPO, ConPyro.

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Recovered tire pyrolysis oil (TPO) is a high-value secondary product from the pyrolysis process.

The market for it will expand by a CAGR of 2.9 between 2021 to 2031. It has enormous potential as a circular, renewable feedstock and fuel for several industries. TPO can be a viable alternative to fossil-based products and help manufacturers meet their carbon and circularity goals. 

Since TPO is a relatively new product, there’s still some discussion about which conventional feedstocks and fuels the recovered tire oil can replace. However, there are many possible tire pyrolysis oil uses for this sustainable alternative. In this article, you will learn the common application and properties of TPO.

What is recovered tire pyrolysis oil?

Recovered TPO is a product of recycling end-of-life tires (ELTs) through pyrolysis. At Contec, the results from the pyrolysis process are: 40 per cent recovered tire oil, 33 per cent recovered Carbon Black, 15 per cent recovered steel, and 12 per cent recovered gas.

Tire material is manufactured to be strong and durable, and recycling ELTs is challenging. Pyrolysis manages to upcycle the materials in ELTs through a thermochemical process. Using this method, tire crumbs, produced by shredding tires, are heated at 550°C in an oxygen-free atmosphere. The complex polymers in old tires are decomposed in a series of thermal and chemical processes to give simpler compounds in the form of oils, char (Carbon Black), and gas.

Contec is one of the few companies operating a tire pyrolysis pilot plant in Europe that produces recovered TPO in Szczecin, Poland. We’ve improved the decades-old pyrolysis process through protected innovations and novel engineering to recycle 100 per cent of the ELTs received.

The high-quality recovered tire oil produced by Contec is rich in aromatic compounds, over 50 per cent, unlike most other crude fossil fuels. Since ELTs are made of natural rubber, the oil is also bio-based.

What are the properties of tire pyrolysis oil?

TPO is a heavy, dark fluid made of a blend of many hydrocarbon families with a high sulphur, nitrogen, and oxygen content.

Recovered TPO is mainly composed of hydrocarbons, including aliphatic, aromatic, and monoterpene compounds. The aliphatic compounds are dodecane and tridecane. The light aromatic compounds are single-ring benzene, toluene, ethylbenzene, and xylene, polyaromatics are naphthalene, and monoterpenes are limonene, according to Jammel 2018.

The composition and specifications of TPO, which determine the properties of recovered TPO, can vary based on the pyrolysis process and conditions, so standardisation is necessary to find industrial applications.

Analyses of recovered TPO and comparisons have shown that its composition and properties are similar to petrol and diesel.

Where is tire pyrolysis oil used?

Recovered TPO can be a circular and eco-friendly alternative to fossil-based petroleum products if its properties and composition are similar to conventional oils.

The main potential of tire pyrolysis oil uses that have been explored are fuel for engines, heating and power generation, and feedstock for producing Carbon Black and other chemicals.

Let’s look at where TPO is used in manufacturing:

1. Tire pyrolysis oil as a New Fuel

According to Han 2023, recovered TPO has a high energy content, but its sulphur content of 1 per cent by weight is more than commercial diesel, which has less than 0.05 per cent by weight of sulphur.

TPO’s low flash point makes it less safe. Therefore, it must undergo treatment and desulphurisation before use as a fuel. After treatment, TPO (44 MJ/kg) has an energy or calorific value close to commercial diesel (45 MJ/kg). Its other properties like viscosity, density, and flashpoint also become similar to diesel after treatment.

Therefore, treated recovered TPO can be blended with diesel and used as a fossil-fuel substitute for motor vehicles, diesel burners, generators, engineering machinery, etc.

TPO is derived partially from the natural rubber used to make tires. It can be considered a biogas and renewable energy source in compliance with the 2009/28/EC European directive. The TPO produced from pyrolysis also has a competitive carbon footprint compared to other first-generation biofuels.

2. Tire pyrolysis oil for Heating

Due to the recovered TPO’s high calorific value of 41-44 MJ/kg and the similarity of its properties to diesel, it can be used as a direct substitute for diesel as a heat source, using the same machinery and pipes, in industrial settings. TPO can be used for heating purposes in industries such as boiler heating, cement, steel, glass factories, etc.

3. Tire pyrolysis oil for Power Generation

Again, TPO’s high gross calorific value makes it an ideal option as a renewable biogas fuel for generating power and cutting carbon emissions. It can replace coal or natural gas, which are expensive.

TPO has the same energy/calorific value as fossil fuel oils, 25-50 per cent more than coal, and 100-200 per cent more than wood.

Most countries around the world import fossil fuels for power generation and heating. All countries use vehicles and discard ELTs, but recycling is poor in many countries. These nations could use ELTs as feedstock to produce economical TPO and cut back on fossil fuel importation.

4. Tire pyrolysis oil for Carbon Black Production

Currently, 90 to 95 per cent of virgin Carbon Black (vCB) is produced using fossil fuel-based feedstocks, rich in aromatic compounds. TPO can be a sustainable and circular feedstock that reduces reliance on fossil fuels for manufacturing vCB of medium to low-reinforcing vCBs.

The presence of high sulphur content is also not a problem and doesn’t influence the yield or the product characteristics. Producing vCB is also scalable, and using TPO as feedstock for some grades can contribute to a circular economy.

5. Tire pyrolysis oil for High-Value Chemical Production

After distillation, TPO yields three fractions, including naphtha, from which it’s possible to extract high-value components like benzene, limonene, toluene, xylene, and phenolic compounds.

According to Han 2023, these compounds are individually valuable for producing industrial commodities:

• Limonene is used to manufacture aromatic agents and solvents.
• Benzene is needed to make dyes, drugs, pesticides, and surfactants.
• Xylene derivatives are used in the fibre industry and for producing polyester fibres.

What are the advantages of using recovered tire pyrolysis oil?

TPO has substantial economic and environmental benefits, largely because tire pyrolysis oil uses can be a substitute instead of virgin fossil fuels in many industries.

Some of the main benefits are:

1. TPO production is more economical than fossil fuels

As fossil fuels become scarce, extraction requires more resources and costs. In contrast, TPO is produced using abundant and economical tire waste as feedstock. Manufacturers in the European Union must pay for their waste management, and any landfilled material can be expensive.

Shredding waste tires and using them as feedstock to produce TPO lowers manufacturers’ costs and provides them with valuable, circular raw materials.

2. TPO from ELTs is more economical than fossil fuels

South Asian countries are opting to use recovered TPO, as natural gas is more expensive, and they’re seeking to reduce dependence on coal for power generation. Similarly, African countries cannot meet the demand for fuel for industries through conventional fuels and find using recovered TPO is more economically viable than increasing the import of fossil fuels.

3. TPO is more attractive than other biofuels

Interest in recovered TPO is increasing to keep up with the boost in demand for renewable energy sources. Recovered TPO can be used in existing fossil fuel facilities, making it an easy substitute. Moreover, it has more energy than ethanol and is more stable and easily transported than biodiesel.

4. TPO reduces land use changes and emissions from mining 

Replacing virgin raw materials with circular secondary tire oil will reduce the associated pollution and environmental costs of exploration, mining, and processing. Less mining also protects pristine biodiversity-rich forests from being cut down to mine more fossil fuels.

5. TPO can be produced in decentralised and small operations

When tire recycling facilities aredistributed throughout a country, they can prevent long-distance transportation of fossil-based raw materials. The shorter transport distance will also reduce the carbon footprint and pollution associated with transporting ‘new’ fossil fuels. Local production of TPO can reduce dependence on imports of fossil fuels, providing assured and uninterrupted feedstocks and fuel supplies to industries.

6. TPO reduces carbon footprint 

TPO has a lower carbon footprint than fossil fuels. Choosing TPO as the raw material for manufacturing will lower the carbon footprint of processes and products and can improve air quality through reduced pollution.

Increasing TPO applications with Contec

As industries become more circular, the opportunities that recovered TPO offers the tire, vCB, chemical, and manufacturing sectors are great. Equally, if not of greater interest, is the possibility of using TPO to generate power and run vehicles, two of the most polluting sectors with significant carbon footprints. Contec seeks to increase tire oil applications by providing a reliable source of high-quality tire oil for these industries. Find out more about Contec’s sustainable TPO.

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Tire recycling is not new.

Currently, the standard method for tire recycling is rubber granulation. However, rubber granulate applications aren’t environmentally friendly or circular and don’t recycle 100 per cent of the materials in waste tires.

Tire pyrolysis, an alternative method of tire recycling, offers the automotive industry circularity and the possibility of reusing materials beyond recycling.

What is tire pyrolysis?

Tire pyrolysis is a form of chemcycling where ground tire waste undergoes thermochemical decomposition at high temperatures in an inert oxygen-free atmosphere to yield recovered Carbon Black (rCB), recovered steel, pyrolytic oil, and pyrolytic gas.

Without oxygen, the polymers in tire wastes don’t burn. The heat catalyses chemical reactions to break down the vulcanising bonds in the rubber granulates. Since 85 per cent of tire components are petroleum- or polymer-based, pyrolytic oil and gas are two major products generated.

All pyrolytic products from tires have circular uses.

• The rCB is a valuable alternative material that can be used to manufacture new tires instead of medium-grade virgin Carbon Black (vCB) produced from fossil fuels.
• The recovered steel can be used again in tire manufacturing.
• The high-quality pyrolysis oil can be used as vehicle fuel or to produce fine-grade vCB for tire manufacturing.
• The pyrolytic gas can run a facility plant and reduce the carbon footprint of all the pyrolytic products produced there.

Tire pyrolysis adapts the well-known process to specifically recycle end-of-life tires (ELTs) since each feedstock needs a different temperature and treatment time.

Three main types of pyrolysis exist — slow, fast, and flash.

Each uses different temperature ranges, heating rates, and residence times to give various products. The distinction between the types is not clear-cut. Furthermore, reactors can be batch or continuous types and use various kinds of beds.

Tire pyrolysis is the most environmentally friendly and safe method to dispose of tires. It produces few poisonous pollutants and has a low carbon footprint compared to other methods — landfilling, incineration for energy, open burning, or rubber granulate civil engineering applications.

Figure 1: Systems boundaries, Buadit et al. 2020. (Image credits: Life Cycle Assessment of Material Recovery from Pyrolysis Process of End-of-Life Tires in Thailand)

How does pyrolysis work?

The products, yield, and quality will all be different depending on the pyrolysis reactor. However, all pyrolysis methods share basic processes, which can be grouped into three steps.

Figure 1 explains the various steps involved in the basic pyrolysis process.

Phase 1: Feedstock Preparation

The processes before actual pyrolysis are crucial and influence the quality of the pyrolytic products. The ELTs are shredded to separate steel and fabric from the rubber components.

Mechanical primary and secondary shredders cut the rubber down to produce 10-50 mm rubber granulates stored in silos.

Shredding tires leads to better quality products than entire tires, as they can be heated faster and more evenly. The separated steel can be recycled. Our process at Contec involves sourcing and using the best quality feedstock during this phase.

Phase 2: Pyrolysis Process

Before the rubber granules are fed into the pyrolysis reactor, the chamber undergoes inertisation to protect the process and staff from combustion.

The oxygen content of air is reduced from 21 per cent by volume to less than 13 per cent by pumping in nitrogen, an inert gas. Not all pyrolysis processes use this step, and by not opting for this step, they risk explosions. Inertisation is crucial to the safety of the process.

Next, the rubber granulates are fed into the reactor and heated to temperatures between 400 and 700°C. Some pyrolysis methods use high pressure and catalysts to aid this process.

The heat leads to various decomposition and volatilization reactions like cracking, dehydration, isomerization, aromatization, dehydrogenation, and condensation. The solid tire waste is converted to volatile gases, steel, and char.

Phase 3: Post-Processing

After passing through the condenser, most of the gas liquefies into pyrolytic oil rich in aromatic compounds, and the un-condensed gas is used as fuel to run the pyrolysis process, which is energy intensive.

The char comes out mixed with finer steel bits and inorganic salts. The solids go under a magnetic separator to remove all traces of steel, which is recyclable. The char is refined and powdered to produce rCB, then pelletised to meet market demand. 

Is the process safe?

The traditional pyrolysis process, despite its benefits, has some risks and is prone to explosions and fire. Historically, the equipment can be damaged, and people have been injured and even killed due to explosions in pyrolysis plants.

Problems can occur because the gases produced from tire decomposition are combustible. If excess oxygen gets into the system because of a mishap or flaw and comes in contact with the gases at high temperatures, the gas can ignite and cause an explosion.

Explosions are a result of a lack of inertisation and proper process control. Therefore, modern tire pyrolysis processes have introduced many security measures to eliminate or diminish the chances of such explosions.

Contec has incorporated stringent safety measures while planning and constructing its protected tire pyrolysis plant to ensure the process is safe for its people, the neighbourhood, and the environment:

1. Contec uses an expensive inertisation process, even though it isn’t legally required.
2. Contec avoids gas pressure buildup by taking the following precautions:
   1. Cleaning pipes even when the plant is in process.
   2. Using two sensors to check pressure each second so that personnel can take steps to correct pressure changes.
   3. Using a relief pipe to divert excess gas.
   4. Carrying out a thorough inspection of pipes, pressure, and gas odour before the start of any run.
3. Contec maintains complete and instant control over the temperature of molten salts, used as a heating medium. These circulate in a different jacket, which makes the system safer. The disposal of molten salts also causes no environmental problems, as their chemical composition is similar to that of fertilisers.

Tire pyrolysis at Contec

Contec has improved upon older tire pyrolysis processes in collaboration with the Warsaw University of Technology and has been involved from the planning stage in setting up the pilot plant in Szczecin, Poland.

The protected Contec tire pyrolysis process uniquely uses molten salts as a heat transfer medium.

Molten salts, historically used to store solar energy, have recently been incorporated into tire pyrolysis. Contec heats the molten salts and pumps them into a jacket where they circulate and remain in a loop around the reactor holding the ELTs’ rubber granulates. An auger inside the reactor rotates to ensure that each rubber particle is evenly heated for the optimum duration so that the rCB is consistently high quality. In addition, staff checks rCB quality every 1-3 hours, so 90 per cent of the product meets stringent quality criteria.

Contec also introduced engineering elements and security steps to ensure that staff has complete control over the molten heating process and that strict safety requirements are met. Less than 15 per cent of all stops in the plant have been non-scheduled stops due to equipment failure. Moreover, molten salts need less energy to maintain their temperature than other methods and can be reused, making the entire tire pyrolysis process more efficient, economical, and eco-friendly.

In addition, the inertisation process ensures that explosion risks are minimised.

The Contec process has ensured that our rCB’s carbon footprint is 80 per cent less than conventional vCB and that our products are circular. Thus, we manage the growing ELTs disposal problem to provide circular rCB, steel, and fuel, to tire manufacturers and the automotive industry to help them become more sustainable and attain their climate-neutral goals.

Get in touch to learn more about our sustainable solutions.

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The commission appreciated our team’s outstanding work, and we managed to more than triple our revenues in 2022. It’s always satisfying to be recognised for hard work and dedication, and this award is a testament to our team’s success.

The recognition from the commission has not only boosted our team’s morale but has also increased our motivation to develop.

We’re confident that with our team’s dedication and hard work, we will continue to exceed expectations and achieve even greater success in the future.

Krzysztof Wróblewski, CEO Contec S.A.

We would like to congratulate the other winners (VIGO Ventures, Piwik PRO, Polskie Konsorcjum Gospodarcze S.A.) and wish them all the best in their future endeavors.

About WEG Awards

The WEG AWARDS 2023 is an awards gala where we nominate WEG portfolio companies in 5 categories:
1. Management Team of the Year
2. Biggest Growth
3. Innovation of the year
4. Globalization
5. Courage in business

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