Aerial view of Kal Tire’s recycling plant near Antofagasta.

Kal Tire, a leading supplier and service provider of mining tires, has designed and developed a plant in northern Chile capable of recycling ultra class mining tires efficiently

By Oscar Martinez, Latin America Editor

Kal Tire has an established presence in Antofagasta, Chile, which includes a retreading plant and an end-of-life (EOL) recycling plant for large off-road (OTR) mining tires. The EOL-OTR plant is a thermal conversion plant, which processes the largest tires. It is unique in terms of the volumes handled, its fully automatic control of the entire process, the gas recirculation system and the use of the energy generated by the process. In addition, the plant can be upgraded to increase its capacity, depending on the needs of the market. It is currently the only recycling plant of its kind in the world.

Recycling mining tires is not new. The mining industry knows firsthand the challenges associated with recycling and final disposal of these massive tires. It’s visible at most mining operations where they have dedicated large areas where mining tires are stacked and stored.

The steel wire waste is removed from the reactor area and trucked to a storage area.

Chile recently passed the Law of Extended Producer Responsibility, which goes far beyond taking care of waste, as it encompasses the entire life cycle of processes and products. It involves incorporating this vision from the design of processes and extending the useful life of products by replacing disposable or single-use items, repairing to reuse and recycling waste.

To comply with the new law, tire importers will need to manage waste streams by establishing ambitious tire collection and recovery goals. The law differentiates the recycling goals for tires according to size, above and below 57 inches (in.). In 2023, the recycling rate for the largest ultra class tires is mandated to start at 25% of imported tonnage and by 2030 it rises to 100%.

With an area of 60,000 m2, Kal Tire’s OTR tire recycling plant allows for the circular processing of EOL tires and generates raw materials that can be reused in other production processes or energy recovery. As an example, Kal Tire’s recycling process for a 63-in. tire (4,000 kg) generates three basic raw materials: approx. 20% steel cables, 40% fuel oil, 5% synthetic gas which is used to power the process, and 35% carbon black, which can be reused in rubber, paints, printing inks and plastics.

The plant design also meets the anti-seismic standards as required by the authorities. Dan Allan, senior vice president for Kal Tire’s Mining Tire Group, explained that the plant was designed and built to withstand grade 8 tremors without major problems. “Even though the plant area is open air, it has a concrete foundation and the risk of earthquakes in Chile is so high that all the engineering must be designed to meet the required standards,” Allan said. “This also makes a lot of sense from a safety perspective because we have materials under pressure. An inappropriate design would introduce unwanted risk.”

How the Process Works

The first phase of the recycling process begins with stacking and cutting. The 57- and 63-in. OTR tires are handled with a system that consists of two cutting machines and a loading machine. Both are automatic and hydraulically controlled. A forklift transports each tire from the storage area to the cutting area.

Two cutting machines are able to produce a total of 18 slices per tire.

The trucks transporting tires to the cutting area normally carry four tires each. It is very important to know the weight of the tires entering the plant area for traceability purposes required by current regulations. Every relevant piece of information is recorded, such as the serial number of each tire, which allows exact traceability from the origin to the plant. In addition, before entering the actual process, each truck is weighed on a scale located in the field to determine the number of tires entering the plant and their tonnage.

Once in the tire storage area, machines cut the tires into six initial pieces which are then broken down again to generate smaller tire pieces.

Telescopic conveyor belts transport tire chunks into the reactors. Once the reactors are loaded, operators close the hatches, and the pyrolysis process begins. Loading the reactor takes up to 90 minutes.

Initially, the reactor is heated using natural gas, and six hours later synthetic gas is extracted, which is the first byproduct resulting from the degradation process of the components that were loaded into the reactor. This syngas then powers the remaining process. 

The pyrolysis process inside the reactors is fully complete after approximately 24 hours with the tires being fully degraded and converted into byproducts. During this process, the oil is extracted, as well as the recycled carbon. When the reactor is opened, all that is left in is the steel. The company plans to eventually install and implement a second stage process to “clean” the carbon black. 

Kal Tire’s tire recycling plant has the capacity to process five 63-in. (20,000 kg) tires every day, generating 8,000 kg of carbon black, 6,500 liters of fuel oil, 4,000 kg of steel, and synthetic gas.

Kal Tire’s recycling plant has two reactors that transform mining tire slices into by-products that will later be incorporated into the circular economy.

Reducing the Carbon Footprint

Carlos Zuñiga, general manager of Kal Tire’s Chilean operations, explained how the company strives to demonstrate to its customers that its tire recycling process substantially reduces its carbon footprint. “Several years ago, we commissioned a study on the process to determine the carbon footprint reduction, so that we could make comparisons, such as diesel with pyrolytic oil, carbon black with recovered carbon black, and obviously steel,” Zuñiga said. “We wanted to know what the carbon footprint of the fuel oil and carbon black would be. This study was carried out by a North American company, then peer-reviewed for independent validation, which issued a report indicating that, effectively, there would be a significant saving in emissions compared to the production of conventional carbon, oil and steel.

According to Zuñiga, apart from the environmental benefits, the greatest benefit for the mining companies is to have a solution that allows them to remove an environmental liability that has been building for many years. “Mining companies are obligated to have a closure plan, and until now there was a solution for all the inputs and waste generated by the mines, except for tires,” Zuñiga said. “Today, there is, and they will be able to acquire it.”

“In the future, it is most likely that, from an economic point of view, some products used by mining companies will have a better price because they are manufactured with the alternative materials generated from the thermal conversion plants,” Zuñiga said. “The conditioning factor for this business model is based mainly on the regulatory framework imposed by the Chilean authorities. Without this regulatory framework, or some incentive to recycle, mining companies would weigh the benefits against the costs.”

In July, Kal Tire’s Mining Tire Group obtained the ISCC PLUS certification for Sustainability and Carbon Certification (ISCC) which certifies that its tire recycling plant in Chile processes raw materials in a circular way, thus supporting the circular economy and promoting a lower carbon future.

“Kal Tire is committed to promoting a circular economy where recycled mining tire products are put to their highest and best use,” Allan said. “This ISCC PLUS certification assures customers that they can reliably use the products from the recycling plant knowing that they are 100% derived from waste materials.”

ISCC is a global leader in developing standards for sustainable materials recycled through chemical processes. Kal Tire’s plant is one of very few tire recycling plants in the world, which the company is aware of, to have achieved ISCC PLUS certification for producing “circular raw materials.”

As Kal Tire is 100% ISCC PLUS compliant, customers of this major tire supplier will benefit as more and more mining companies seek to demonstrate that its operations are run in a sustainable and circular way.