Tires literally serve as a foundation for transportation in North America. According to data from 2015, there are approximately 300 million transport units on roads and highways in Canada and the United States. Simple computation suggests that at any time, 1.2 billion tires can be in contact with highway surface.

Obviously, once those tires are out-of-life, it is necessary to store them somewhere, for example, in a landfill. But this is an old-fashioned practice, as more innovations in tire recycling have been introduced.  These advances signify that a big number of end-of-life tires undergo shredding and new products are created from the recycled rubber.

Nevertheless, passenger tires aren’t the only rubber meeting the road – or, in some cases, the rock and dirt. Heavy off-road vehicles such as mining trucks and earthmoving equipment also run on rubber. These tires, being rather larger than their passenger-vehicle cousins, pose an even greater problem when it comes to end-of-life treatment. Most of the time, the scrap yard has been their final destination, leading to potential environmental challenges.

Seeking better ways of handling and recycling of end-of-life OTR tires

As its customers expressed their desire to seek better approaches to dispose of their OTR tires, Kal Tire started looking at its options for recycling. According to Bob Bennet, Kal Tire’s vice president of Canadian branch of Mining Tire Group, Kal Tire has considered themselves obliged to assist the buyers with the long-term maintenance of the purchased tires. He also says that disposal has been an ongoing problem for their clients.

Generally, the clients with OTR tires have had to find uncommon ways for disposal, taking into account local laws. Bennet explained that clients could have buried their waste tires, as some laws don’t prohibit that. Even though it’s harmful for environment, no better alternative was available for companies. Alternatively, tire owners could give their tires to benefit the cattle industry, as the old material could be cut and used as a feed trough.

The approach which gains popularity for tire disposal worldwide is pyrolysis, however the end of the process sees a lot of remainders which also need to be disposed of. The leader of disposal practices now is shredding.

According to Bennet, shredding has a variety of applications and is widely used in the passenger and medium truck business. The result is a nice product that can be used in a variety of applications – it can be used for running tracks, can be compressed into mats for high-wear areas or cushioning. It can be used in highway construction, and in newer applications such as sub-base in engineered landfills or in road construction as an alternative to gravel or aggregates.

The sheer size of OTR can be a challenge in case of shredding, as it is difficult to recycle and shred a 63-inch mining tire. Therefore, Kal Tire turned to the experience of tire recycling industry.

Liberty Tire, one of the key tire processors in North America, based in Legal, Alberta, became a collaborator of Kal Tire. Neil Bansal, regional vice president of Liberty Tire, said that till the recent times, the facility processed 40,000 tons of passenger tires and not heavy-weight truck tires per annum. He added that during the times when Kal Tire decided to collaborate with Liberty Tire, their equipment wasn’t capable of shredding large mining tires. Partnership with Kal Tire allowed to do that in 2016.

For the past years, Kal Tire has been a leader in this way of recycling due to its close connection to clients of heavy vehicles. Bennet revealed that it took them 3 years to engage with the clients. And they still work with them, and wait for some customers to send the product over. Some clients seriously consider the alternative. He explained that The OTR tire recycling program is managed from customer sites by Kal Tire representatives. He also explained that the company is responsible for the weighing, the collection and the documentation needed for tires. Normally, they are brought to Liberty’s facility, which is in the northern part of Edmonton. Once they reach this destination, the tires are weighted and documented yet another time.

At that site, the preparation for shredding begins for the tires, which have various sizes and can be as large as 63 inches in size. More preparatory work may be needed depending on the sheer size of the OTR before the actual shredding.

Bansal said that the tires can be so huge, that it is impossible to put them into machine. In addition, debeading may be needed prior to shredding. Mechanical shears normally cut tires into dozen of pieces when they are moving into the recycling line. To prevent difficulties and avoid blade wearing, bead is taken out prior to shredding

The bead on a 63-inch tire is around four to six inches – that would just gum up the teeth. So, they extract the bead and dispose of it as a separate entity. It’s rubber-impregnated steel, but it’s high quality steel – there’s value there. Once the tires are cut down to size, the shredding process begins. Liberty Tire uses a Granutech-Saturn shredder for processing of the large tires, and thanks to the company’s extensive experience with smaller tire sizes, is able to manage the various challenges of rubber shredding.

After the cutting process, Granutech-Saturn shredder is used by the company to deal with huge tires. Liberty Tire’s extensive experience in shredding regular passenger and truck tires helps to handle challenges occurring while shredding.

Bennet said that the company has developed a strategy to work with equipment in an effective way when dealing with rubber. Normally, they apply a closed-circuit process, instead of a common crushing circuit, in which any fraction can be visible on a screen deck and can be then accumulated, whereas the larger rubber will be still processed until it develops a design-size fragment.

Bansal highlighted that there is a strict regulation at the facility to secure the most effective operation of the system, which handles approximately 14 tons of rubber per hour. He said that the main aim is to create standard size chips, not on just large chips, and this demands more time.

The end result of Liberty’s OTR tire shredding operation is a collection of products that can be used in different ways. According to Bansal, one of the main areas they are targeting is tire-derived aggregate (TDA). TDA has seen interest within Alberta and elsewhere for use in engineering projects such as landfill construction, where it can replace aggregate in the leachate layers. It can be used as part of the subgrade for roads and in some other areas which would normally involve traditional aggregates as well. Other markets for the end product include tire-derived- fuel (TDF), mulch, crumb rubber and similar products.

Bennett said he expects to have around 12,000 to 15,000 tons of tires processed per year, with the goal of reducing existing stockpiles of waste tires spread around at Canadian mines. Offering the option of recycling to Kal Tire customers is a way to close the circle of tire life cycles, he said.

The company helps source tires, helps spec tires, manage the tires throughout their life cycle on the mine site, but, according to Bennet, there was a gap when it came to end-of-life tires. He adds that the company’s tracking software will be able to give customers the comfort of knowing the full life cycle of the tire, right through to disposal – where before it just stopped at scrap in a stockpile.

Bennett also adds that there are some minor costs involved in the shipping and final handling of the tires, but that the disposal program isn’t really intended to be a money maker for Kal Tire. Reportedly, the company is helping solve a problem to which there’s no conventional solution available on the market today.

Article source: Recycling Product News