weibold! Academy: Applications for Fibers from End-of-Life Tires

Dear Readers,

Month by month, our weibold! academy series dwells deeper into the world of tire recycling, its products and applications. In case you have missed our previous w! academy articles, you can find the links at the end of this article.

This month we will elaborate on applications for fibers from end-of-life tires.

The average passenger tire contains approximately 1.1 kg (2.5 lbs) of fiber, while truck tires may have much less. The fibers are a combination of polyester, rayon and nylon. Fiber is liberated from rubber and wire using different methods during processing. Mechanical vibrating screens and pneumatic systems can liberate fiber from other tire material when shreds are about 20 mm (¾”) in size; however, some material will re-pass through the system, as it is not yet liberated. The more the material is passed through, the shorter the fibers become. This can make the material less marketable for certain applications. Vibrating air fluidized beds are also used to separate fiber from rubber. The resulting fiber is “fluffy” in nature, resembling cotton, and is often referred to as “fluff.” Because the material is low in bulk density, it may need to be baled in order to transport to market it successfully. Vacuum systems often collect the fiber material or convey it to its final destination due to its light nature.

Tire derived fiber is largely an underutilized commodity. If markets were better developed and offered a sufficient price, processors would be more prone to recycle tires in the way where they remove and prepare fibers for reuse.

From the whole range of applications identified for separated tire-derived fiber, only its use as a fuel appears to be commercially significant. Landfill engineering and cement kilns are also relatively large sinks for tire fiber as this material is part of (and not separated from) the shredded or whole tires used in these applications. Research has identified a broad range of applications for tire-derived fiber, but many of these are still at the research and development stage.

Some of the asphalt producers who use rubber granulate include the fiber as well in some products, as it helps form a matrix that adds strength to the material.

It can also be used as reinforcing component in manufacturing masticated rubber products such as mud flaps, rubber sheets and rolls.

Tests showed that adding tire fibers in concrete can improve the shrinkage performance of reinforced concrete and although there might be a noticeable decline in the compressive strength of the concrete there is an increase in the toughness of the concrete.

Carpet backing is another application where we monitored efforts to incorporate it into the production process. However, tire fiber usually has significant amounts of contamination in the fiber—including both rubber and wire—which makes the material unsuitable for this purpose without proper cleaning. Also longer fibers are preferred over short ones.

Given the fact that the fiber has a relatively high btu value (similar to tire derived fuel) one market expansion opportunity for any recycler is to approach cement kilns to explore whether and how they could begin to use it to complement existing fuel sources. The btu value usually is between 30,000 and 35,000 btu per kg (14,000 to 16,000 btu per pound), dry weight.

Summary:

  • Summarizing the specific properties of tire fibers the material is reinforcing, sound deadening, insulating, and with a high btu value.
  • Beyond use as fuel, tire-derived fiber is highly absorbent and lightweight and has low or no cost, potentially making it a possible replacement for materials in some other markets.
  • Industrial applications for the fiber are limited, but market appetite is growing.
  • Most of the scrap tire recyclers are primarily interested in producing good-quality rubber rather than producing clean fiber.
  • For tire-derived fiber to be used in many of the newer applications, auxiliary equipment to clean the materials to an acceptable quality would normally be required. This would lead inevitably to additional processing costs which are often difficult to pay off based on the average low volume a single tire recycler produces.

Please contact us to request more information on this topic. We will be happy to help you!

Links to our previous newsletters:

  1. Welcome to weibold! Academy
  2. weibold! Academy: Recycled Rubber Output Spectrum and Rubber Granulates
  3. weibold! Academy: Rubber Granulates, Rubber Powder, Tire Derived Steel and Tire Derived Fiber
  4. weibold! Academy: Tyre Recycling Value Chain
  5. weibold! Academy: Applications for Tyre Recycling Plant Output
  6. weibold! Academy: Rubber Granulate Applications
  7. weibold! Academy: Rubber Powder Applications – Rubber Industry
  8. weibold! Academy: Rubber Powder Applications – Surface Coatings
  9. weibold! Academy: Success Factors in the Tire Recycling Industry 
  10. weibold! Academy: Understanding Tire Recycling Technology
  11. weibold! Academy: Total Quality Management in Tire Recycling

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