How Are Tires Recycled?

‍Tire Recycling has changed

Piles of used tires used to plague the landscape in major cities and fill landfills with masses of rubber. This was before good methods were designed to ground up and reuse existing tires. Rather than exposing tires to the heat and risking the potential for uncontrolled burning, recycling processors have developed ways of getting the most of the rubber from tires.

Removing steel

Many tires have steel bands installed to keep the tire composed and structurally sound while under driving stress. Before tire recyclers start to shred the rubber, they first remove the steel or nylon parts that make that structure happen using magnets to pull them out. Tires can have over 2 pounds of steel within their bands, which composes about 10-20% of the tire’s overall weight.

Most often, the steel is melted to create new products as melting steel requires far less energy than creating new steel. Tire steel does have limited applications, as it can already be rusted or have contaminants within. The United States is the largest exporter of tire steel.

How is tire rubber recycled?

Tire processors use a couple of methods to break tire rubber into smaller pieces. Mechanical,  cryogenic, and heat.

Mechanical

Processors use a mechanical grinder to tear apart tires that don’t require further breakdown to make the after grind rubber functional. A mechanical grinder involves rotating mechanical “teeth” that can exert tremendous weight and pressure onto tires. These can be setup in specific ways, but most often grind tire rubber into 2 inch strips after which they are chemically treated.

Cryogenic

You’ve probably heard of cryogenic methods of keeping people alive using extreme cold. In this case, tire remnants are frozen by liquid nitrogen and broken into smaller parts using what amounts to mechanical hammers while other non rubber parts, like steel, are whisked away by magnets.

Pyrolysis

You might have put together “heat” from pyro, and you are right. Tire processors can use a heat method in which tire rubber is softened in an oven before being sent to a shredder.

How is the resulting tire rubber cleaned?

With tires shredded into smaller pieces and any remaining steel removed, tires are then cleaned using a mixture of water and other cleaning substances. The purpose of cleaning is to remove any road substances and any residue resulting from the process of tearing the tires apart.

What products can recycled tires make?

Recycled tires do an excellent job of making a few products, including

Gravel substitute

Gravel is heavy and can be expensive to move. Recycled tires do a similar job of becoming a layer in a freeway, backfill for roads, and an aggregator for ditches. Homeowners near railroad tracks like tire chips over gravel, as they absorb the vibration of an oncoming train better than gravel. These are especially useful in colder places as rubber doesn’t freeze easily.

Environmentally and labor speaking, tire rubber requires less energy and gas to transport. Why? Tire chips and rubber weight about ⅓ as much as gravel - less gas burned to carry.

Playgrounds and Mats

Ground up tire rubber makes an excellent, soft, and durable fill for playgrounds and anti-fatigue mats. Tire rubber is both supportive and soft, reducing the chance of injury when kids fall. Parents also welcome removing rubber bits from shoes instead of tracking wood chips home. Workers who do a significant amount of standing also appreciate the support a tire rubber mat offers.

Landfill Liner or Cover

While landfills aren’t normally the best place for tires, a torn and shredded tire can be helpful in replacement of ash or coal. Tire chips hold balanced temperatures better, are more readily available, and are cheaper than other methods. In previous decades, tires were often thrown into landfills. More recently, landfills can use shredded tires to prevent some of the same problems they used to create with being excessively filling and likely to cause fires.

Tire Fuel

We don’t quite mean gasoline here. Tires can be burned in a safe manner and are often used in the making of cement, paper, and pulps. Tires are cheaper and offer heat advantages compared to other methods of producin heat in these factories. In case tire burning doesn’t sound quite right to you, these are regulated and allowed the Environmental Protection Agency.

New methods of recycling tires

While current methods of recycling tires are appreciated and tire processors and manufacturers have come a long way in avoiding tire fires and reusing rubber, science is helping go further. The list of products made from tire rubber isn’t all that long for a rubber that is rather plentiful.

New labs are being designed to use organic processes to break down the sulfur within tires. These processes leave only the organic compounds that can be reused for more purposes, including making new tires.

Companies like Lehigh also have a hand in starting the process of transforming old tires into new ones - with some tire companies using recycled rubber for up to 20% of their future tires. The number of tires being recycled in the United States is up - and still going up, so their types of labs are certainly relevant for the future.

The future of recycling aims to make recycled rubber usable for products besides cushioning and safety. Manufacturers can use significantly less new rubber and need to extract much less rubber if they can use the existing rubber that is still literally on the road today.