A 2020 study in Australia came up with some surprising numbers on the country’s off-the-road tire (OTR) industry. In 2019, the Australian mining industry generated a staggering 68,100 tonnes of used tires.
Of that number 93% or 63,300 tonnes were disposed of onsite – either piled up or buried. A further 3% were sent to landfill (2,000t) while just 1% (700t) were recycled, with the remainder stockpiled or used in civil engineering.
Tires don’t degrade, so anything that is not recycled becomes part of the landscape indefinitely. There are likely millions of ELT buried or piled high at mining locations around the world – and there are only so many haul road safety berms, feeding troughs, playground surfaces and lawn mulch where rubber can find other end uses.
Needless to say, for an industry struggling to burnish its ESG credentials, tires are a big black mark on its environmental reputation and an easy target for green activists.
Last month MINING.COM toured a facility in the heart of Chile’s copper region and home to many of the world’s largest open cut mines, in a showcase for how this intractable problem can be tackled.
Joint venture
Kal Tire, a B.C.-based family-owned business that traces its roots to the early 1950s, operates a first of its kind tire recycling plant in La Negra, an industrial area outside Antofagasta and the mining epicentre of the world’s top copper producer.
Dan Allan, Senior Vice President of Kal Tire’s Mining Tire Group, says the company is not trying to reinvent the wheel: “We did not set out to be the biggest or take over the world with tire recycling.
“Our mining customers had a problem and we worked to find a solution.”
Kal Tire’s operations in Chile, the first outside its Canadian home base, started in 1997 and today the company’s mining division provides services to more than 150 mine sites across five continents.
The thermal conversion plant started running on a trial basis in 2021 after around three years of R&D (initially in Italy) and entered commercial operation this year.
In September last year Kal Tire signed a joint venture deal with Japanese conglomerate Mitsui & Co. to expand and further develop the business. Mitsui’s annual revenues are nearly $100 billion and the company has extensive investments in mining and metals around the world.
Carbon black
Pyrolysis is a decades old, relatively simple process but setting up a plant to handle so-called ultra-class tires used on mining trucks is a specialist undertaking. A single truck tire can weigh as much as five tonnes, so simply transporting it from often remote locations is a challenging and costly task.
Kal Tire’s recycling facility has the capacity to process five 63” or 1.6m diameter tires weighing 20,000 kilograms every day. The process creates 8,000 kg of carbon black, 6,500 litres of oil, 4,000 kg of high-tensile steel (sought after as scrap for steelmaking) and enough synthetic gas to fuel the plant itself for seven hours.
Mining truck tires are typically manufactured with mainly natural rubber with only a small percentage of the synthetic equivalent. Close to 100% of the constituent material going into the facility can be repurposed and the plant has been designed to be scalable and, crucial in this part of the world, can sustain earthquakes of up to 8 on the Richter scale.
Legislation roll-out
Chile is a leader in pushing for greener tires with a new law that mandates that 2023 through 2026, 25% of all mining tires must be recycled. This rises to 75% in 2027 and 100% by 2030. Estimates put stockpiles of used OTR tires in the country at 500,000 tonnes.
Kal Tire set up the venture with input from the Chilean government and Allan says legislation is a key driver of greater recycling in the global industry.
South Africa has introduced a small recycling levy on new tires but efficacy of the program, given the economics of tire recycling, remains in doubt. Australia and other countries are looking at instituting programs while Canadian legislation, introduced in 2016, covers shredding and repurposing of rubber, not full recycling.
Stand-alone industry
Allan could not be drawn on exactly where and when Kal Tire Mining may build a plant next, but given the ESG impetus in global mining and ever-stricter environmental rules being put in place by regulators, its expansion plans may not take long to become public.
Allan fully expects other entrants into the market and tire recycling to be a stand-alone industry with tire manufacturers like Bridgestone or Michelin, despite their size and resources, unlikely to enter the market in a significant way.
How mining tire recycling may evolve around the world is not yet clear either. Given the size and remoteness of many mines, on-site solutions may work better in certain instances given transport logistics and costs while in other regions a central hub approach may be the ideal solution.
Where it fits into miners’ economic structures is also being considered and Allan believes shifting tire recycling from operational costs to remediation budgets may offer a solution.
rCB industry growth
Allan says Kal Tire does not have to look for customers for the plant’s recovered carbon black (rCB) – it’s a rapidly growing industry with some analysts predictingfor the next five years. rCB can be used to produce tires and a variety of plastic products, inks and coatings.
North America is the largest market for rCB and pricing in the first quarter of this year was pegged at some $2,300 a tonne (high grade FOB Texas). And that is after some steep declines in 2022 over worries about growth in the automotive sector.
Construction is about to start on the next phase of the plant to further refine and standardise the carbon black output through processes that include milling and pelletizing .
Earlier this month the recycling plantInternational Sustainability and Carbon Certification (ISCC) PLUS, a voluntary program to advance standards for chemically recycled materials to promote the so-called circular economy.
Allan says the question he’s asked most frequently is – what about conveyor belts?
What to do with end of life conveyor systems – some of which, like at the Mt Saddleback mine in Western Australia, run for 51 kilometres or nearly 32 miles – is as big a headache for the mining industry as tires. Kal Tire has researched the issue, but decided given the different composition and unique properties of conveyors, it requires a different set of solutions.
Last resort
Kal Tire’s Chile office employs some 330 workers and counts as customers a number of mines in the region synonymous with the global copper industry.
Particularly at open cut mines, tires can easily be in the top five concerns for miners in terms of operational costs, says Allan. At roughly $60,000 per tire for the largest sizes, outfitting six-wheeler dump trucks is an expensive undertaking.
Without damage – which even at these sizes can be caused by something as simple as a pebble getting stuck in the tread – the tires last only around 6,000 hours.
And in places like the bone-dry Atacama, conditions for tire wear and damage is in fact favourable.
Somewhat counterintuitively, water is a tire’s biggest enemy, said Carlos Zuniga, General Manager of Kal Tire Chile during a tour of the adjacent repair and vulcanization plant.
“Tire recycling is always the last resort,” says Zuniga. “The main priority is to extend the life of the tire.”
