Published Feb 23, 2017
Tire shredding is a very common way of preparing scrap tires for disposal or recycle. In order to dispose of tires in a landfill, they must be shredded to various sized chips. The size required depends on the state or area you live in. Tire shredding is also used for recycling tires; crumb tire or tire mulch can be reused to create surfaces on playgrounds, athletics tracks, roads, and more. Many companies are investing in their own tire shredding systems. These companies are then able to sell the shredded tires and make a profit on them, instead of paying someone else to remove and dispose of their tires!
Tire shredding machines serve an important purpose. You may wonder, though, how does a tire shredder work, exactly? It’s good to understand the mechanics of these powerful machines; knowledge is power, after all, and it can help keep you safe while you shred tires. And, if you are debating the benefits of tire shredding, this may help you understand if a tire shredding machine is what your company needs.
Primary shredders are the first machine that a scrap tire will encounter. These hefty shredders can take a whole tire and turn it into a pile of 2”-6” rough shreds; they can typically process between 10-30 tons of rubber per hour. Primary shredders can have a single shaft or two shafts.
Single-shaft shredders are great for creating uniform pieces. For instance, the Eco Green Monster, our single-shaft tire shredding machine, can create 2” chips with the insertion of the proper screen. Screens act as a filter on single-shaft shredders, making sure that only the right sized pieces are allowed through. Larger pieces are re-cut until they fit through the screen; this feature ensures that every piece ends up a similar size, making it easier to use them for what you need.
Two-shaft shredders create rougher shreds, since they typically do not have the screening equipment that a single-shaft shredder does. However, the process of shredding is faster, and two-shaft shredders are typically more durable and long-lasting. The Eco Green Giant, our two-shaft tire shredding machine, can process up to 30 tons of tires per hour, and outputs 8” rough shreds. Screens can be fitted to create smaller output, if needed. Deciding between a single-shaft or two-shaft shredder really just depends on your needs.
A primary shredder is only the first step in tire shredding, as these large pieces will then be turned over to a secondary shredder for further refinement.
Next up, the rough shreds of tire will be put into a secondary shredder, also known as a grater. These will refine the tire shreds down to chips that are just 1” or smaller. Tires contain steel wires which need to be filtered out, and the secondary shredder does this as well. Different screens can be fit onto the grater to create output as small as .5”.
After going through a grater, the clean mulch is then put into a granulator. This high-speed processing machine removes other materials from the rubber, such as nylon and polyester, and produces what’s known as crumb rubber. Crumb rubber is the result of very fine tire shredding, with each “crumb” being around 3/8” in size.
If an even finer shredding is required, the last step in tire shredding would be milling equipment. The crumb rubber produced by the granulator is put into a cracker mill, or fine grinder, and is reduced down to just 2mm or smaller, creating what is essentially a rubber powder.
To sum it all up, each step of the tire shredding process is about refining the rubber pieces more and more. Primary shredders work by slicing whole tires up into rough chunks, pieces about 2” in size. Each machine that is used after that will make the pieces smaller, and will also take out any material that was in the tire that is not rubber. Steel wire, polyester, and nylon are all removed during the tire shredding process, leaving you with a pure rubber powder.
If you are considering purchasing a tire shredder or shredding system, consider what the purpose of the outputted material will be. How refined does your tire shredding need to be? Are you just looking to create pieces small enough to dispose of in a landfill? Are you interested in creating crumb rubber or rubber powder which can be sold and recycled? Are you using the rubber to produce other materials? These questions will help you decide on what type of machine or machines you need.
TDS, or Tire Derived Shreds, are what you will get from a primary shredder. They contain steel, fiber, and rubber, and can be used for energy production, as a fuel additive, or for civil engineering purposes. A secondary shredder will produce Wire-Free Chips, also known as Rubber Mulch. These can be used for landscaping, playground surfaces, and other engineering purposes. The secondary shredder will also leave you with scrap steel, which can be sold for an additional profit.
Crumb Rubber, the output from a granulator, can be used for athletic tracks and fields, or can be used as part of a rubber sealant or asphalt. And lastly, Rubber Powder, the smallest form of shredded tires, can be used in a wide variety of ways. Asphalt, roofing materials, polymers, injection molding products, and more can all benefit from the use of Rubber Powder.
Each size of rubber shreds can be used for multiple purposes, so there’s no wrong choice. It all just depends on your company’s needs and what your ultimate goal is with your shredded tires.
For More Information
For more information about the various stages of tire shredding, check out Eco Green’s available tire recycling systems. Our experts can help you figure out the right equipment for you, no matter what type of tire shredding you are interested in.
Source: Wilson, David. “Shredder Selection Basics.” Recycling Today, August 18, 2009. Accessed January 31, 2017. http://www.recyclingtoday.com/article/shredder-selection-basics/.
about the right equipment for you.