Is it better to pyrolysis recycle tires or burn them for energy?

As a bulky, durable product containing multiple components, tire recycling presents multiple challenges to the environment, energy, and resource cycles. Today, we will discuss two main methods of waste tire recycling: tire pyrolysis and direct burning for power generation.

Waste tire recycling methods

Tire Pyrolysis Recycling

Tire pyrolysis is a thermochemical process that decomposes tire rubber at high temperatures (typically 300°C to 400°C) in an oxygen-free environment. The absence of oxygen prevents burning, instead breaking down the complex polymer chains of rubber into various valuable components：

Pyrolysis Oil (40-50% yield): This is a heavy fuel oil that can be used directly in industrial burners, furnaces, or boilers. It can also be used as a heating system in heavy oil power plants. With further refining, it can be upgraded into diesel fuel serving as a feedstock for the petrochemical industry and for diesel generators.

Applications of tire pyrolysis oil

Carbon Black (30-35% yield): This is a solid, char-like material. While not always of the same grade as virgin carbon black, it can be reprocessed and used as a reinforcing agent in new rubber products, as a pigment, or as a raw material for manufacturing plastic masterbatch.

Pyrolysis carbon black usages

Steel Wire (10-15% yield): The steel belting embedded in tires remains intact and is easily separated. This clean steel scrap is of high quality and is commodity for steel mills and foundries.

Application of steel wire obtained by pyrolysis

Syngas: The non-condensable gases generated during the pyrolysis process are typically recycled to heat the pyrolysis reactor, making the system largely self-sustaining and reducing external energy requirements.

DOING tire pyrolysis plant syngas recylcing system

Advantages of Tire Pyrolysis:

Material Circularity: Pyrolysis is fundamentally a recycling process. It recovers and repurposes the core materials of the tire, keeping them in the economic cycle. This reduces the demand for virgin resources like crude oil and virgin carbon black, whose production is highly energy-intensive.

Reduced Carbon Footprint: By creating reusable materials that displace virgin counterparts, pyrolysis often results in a lower net carbon footprint compared to both burning and the production of new materials from scratch.

Controlled Emissions: When operated within a fully enclosed system and with proper emission control devices (like scrubbers and desulfurization tower), pyrolysis plants can effectively manage and minimize the release of pollutants. The oxygen-free environment inherently prevents the formation of dioxins and furans, which are major concerns in burning processes.

DOING pyrolysis plant environment protection devices

Waste Elimination: The process achieves a very high diversion rate from landfills, with up to 90% of the tire's mass being converted into useful products.

DOING tire pyrolysis plant profit analysis

Tire Burning for Energy

In this method, shredded tires are used as a supplemental fuel in cement kilns, pulp and paper mills, or dedicated power plants. Tires have a high calorific value, comparable to or even higher than coal, making them an attractive alternative fuel.

The Process and Its Justification:

The primary benefit of tire burning for energy is energy recovery. By replacing fossil fuels like coal, it can reduce the reliance on non-renewable resources and lower the carbon emissions associated with fossil fuel burning (as the carbon in tires is considered biogenic to a small extent and partly fossil-based). In industrial settings like cement kilns, the high temperatures and long residence times are said to ensure relatively complete burning, and the steel wire and ash minerals can be incorporated into the cement clinker.

Practical Drawbacks of Burning:

Irreversible Resource Loss: Burning tires is a linear "take-make-dispose" process. The valuable materials—the rubber, carbon black—are permanently destroyed, converted only into heat and ash. This represents a significant loss of potential resources.

Emission Concerns: Despite advanced air pollution control systems, tire burning remains a source of concerning emissions. These include:

1)Heavy Metals: The metals used in tire compounding can volatilize and be released into the atmosphere or concentrated in the ash.

2)Polycyclic Aromatic Hydrocarbons (PAHs): Incomplete burning can lead to the formation of these hazardous compounds.

3)Dioxins and Furans: The burning of chlorine-containing compounds can form these highly toxic and persistent organic pollutants under certain conditions.

4)Particulate Matter: The process generates fine particles that must be controlled.

Public and Regulatory Opposition: Projects involving tire burning, especially in dedicated power plants, often face significant public opposition due to perceived health risks from emissions, making permitting and operation challenging.

Lower Economic Value Creation: The sole product is energy, which has a relatively low market value compared to the suite of products (pyrolysis oil, carbon black, steel) generated by pyrolysis.

While burning tires to energy can be a viable waste to energy option in specific, well-controlled industrial contexts, it is ultimately a linear process that fails to capture the full value locked within waste tires. It treats tires as a problem to be disposed of, rather than a resource to be harnessed.

In contrast, tire pyrolysis represents a more advanced and sustainable waste tire management and recycling way. It aligns directly with the principles of a circular economy by deconstructing waste into its core components and returning them as industrial feedstock. By producing pyrolysis oil, recovered carbon black, and steel, it creates a closed-loop system that conserves natural resources, reduces environmental impact, and generates greater economic value from waste.

DOING tire pyrolysis recycling plant manufacturer

If you are evaluating the opportunity in waste tire recycling, we invite you to contact DOING to explore how our pyrolysis solutions can be tailored to your specific local conditions and business goals. From initial feasibility assessment and plant design to commissioning and operational support, we provide the comprehensive partnership.