Repurposing end-of-life tyres

Repurposing end-of-life tyresTHE good news according to the Freedonia Group is that global demand for tyres would climb 4.7% a year through 2015 to 3.3 billion units, advancing along is the tyre market, which will be valued at US$ billion. Now the downside is that there will be a resulting glut of end of life tyres finding their way to the landfills and stockpiles later on.

Recycling the tyres, not to be reused but to recover the mine of useful components such as oil, steel, gas and carbon and char through tyre pyrolysis is a viable technique albeit labour and cost intensive.

The technique had been used rather crudely for years to produce coke and coal and is based on the principle of heating a material without oxygen in a reactor as it decomposes,

Although recent tyre pyrolysis systems are more refined now, most of the systems in use are targeted at producing output for low-key end-market sectors.

UK-based PYReco, Europe’s first large-scale tyre pyrolysis company uses an advanced proprietary process called Zerowaste Process (PZP) via a “critically, controlled patented procedure” in obtaining oil, gas, fuel and carbon black in old rubber tyre feedstocks.

Noel Harasyn , Managing Director exolains that their work at PYReco encompasses a more complex “pyrolysis” than what the term is normally connoted.

“There are thousands of lower cost pyrolysis systems available. Unfortunately, many of them randomly focus on the raw gas and oil output, while others produce a pyro-carbon char product with a significantly lower market demand and value. The processes are usually ‘batch’ kilns that require emptying after each ‘firing’ and are heavily dependent on manual intervention, “ he said.

Emphasising further that tyre pyrolysis, per se, does not recover valuable components form tyres, Harasyn explains that their PZP can efficiently reclaim high revenue carbon, the PZP Eco Black, which is worth US$ 1,600 per tonne in the market.

“PZP Eco Black is dependent as much on the carbon finishing equipment as it is on the initial heat process.”, he said,

PYReco also produces PZP Steel, PZP Oils ( which contains a multifaceted mixture of aliphatic and aromatic hydrocarbons), and Gas – each one fetches high market value, he said.

The PZP in the UK enables the combined energy outputs of the PZP Oil and Gas to form high-pressure steam to power steam turbines to generate electricity, he added.

Not compromising on safety
Due to its mechanism, tyre pyrolysis may pose risks especially if oxygen leaks occur that may expose workers to chemicals and fumes.
Moreover, a recent study by Stockholm University researchers shows that automobile tyres may contain potential carcinogenic dibenzopyrenes—a type of high molecular weight polycyclic aromatic hydrocarbon (PAH)—that could leech to the environment through tread wear, stockpiling (of scrap tyres) and emissions from pyrolysis (of scrap tyres). PAHs from recycled tyres also cause pollution. .

PYReco’s system has taken 15 years to develop, Harasyn said, ensuring that safety is taken as a priority consideration. He also warrants that their equipment, all purpose-built in North America, the UK and Continental Europe are assembled and built on site..

“PYReco can confirm that it conforms to European regulations for its own process. Having spoken to buyers of lower cost systems , we know that some of those systems would fail the UK and the EU environmental regulations, as well as those set by the USA and South Africa.”, he averred.

Citing that PYReco is taking health and safety standards seriously, Harasyn said, “ The PZP unit does not have any emissions to air from the tyre material. Waste heat is used in the carbon pelletising process to ensure a high heat efficiency. Any emissions into the air emanate only from the system’s gas burners, but in any case, have to meet the limits proscribed by the United Kingdom Environment Agency.”, he assured, adding “There is some wastewater produced, predominantly from the steel product cooling quench bath, boiler blow-down and domestic use. The emissions to water are routed to sewer and treated to comply with the plant’s trade effluent consent. PYReco’s low emission plant makes it one of the cleanest processes in the region.”

Ensuring safety of workers, Harasyn said that the PZP process purges the calciner or kilns of oxygen by the injection of nitrogen to ensure that “no flame can occur” because once the material “burn up” during the process, the valuable carbon will be destroyed.

Keeping at the supply
Whilst efficient, the PZP process is expensive, Harasyn said that the plant, refining and steam generation facility cost around U$150 million. But the cost is significantly outweighed by the quality of the output. “ (PZP) is warranted by one of the world’s largest engineering firms and most importantly, the return on investment is excellent.”, he said.

To support the equipment cost, Harasyn emphasised the importance of scale. “About 60,000 tonnes processed per annum is the minimum requirement to support the equipment costs.”, he advised.

Moreover, he said that the high value achieved from the sale of the PZP products ensures continued profitability.. “For every 60,000 tonnes of tyres PYReco processes, it reclaims circa 20,000 tonnes of PZP Eco Black, 20,000 tonnes of Eco Gas, 15,000 tonnes of Eco Oil (grade 2) and 7,500 tonnes of Eco Steel.”

PYReco sees a gold mine in the landfills with the end of life tyres ready to be reclaimed. If for anything, PYReco’s ability to reduce tyre waste is only limited by the tonnage of waste tyres available to process in any region or country. (RJA)

Noel Harasyn, Managing Director of PYReco admits that, tyre pyrolysis is often confused with waste pyrolysis and tyre incineration, both are known to pose certain levels of risks. In lieu of the standard pyrolysis and reclamation process, PYReco makes a cut for safety and efficiency:

Pre-treating the waste, which usually involves sterilising it and separating some of the impurities, especially glass, grit and metal.
“PZP does not require pre-treating other than shredding the tyre. “

Heating the remaining waste, mainly organic pulp, to produce gas, oils and ash.
“The PZP process does require heat but only in relatively small quantities in relation to the energy released by the process. In addition to a net energy gain, PZP also produces considerable quantities of pyro-carbon and steel.”

Scrubbing’ (cleaning) the gas to remove some of the particulates, hydrocarbons and soluble matter.
“Flue gases from steam generation in the PZP process are cleaned in the normal way. The pyro-carbon contains materials needed by the motor industry and requires no cleaning.”

Using the scrubbed gas to generate electricity and, in some cases, heat (through combined heat and power – CHP).

“PZP reclaims valuable materials in addition to the oil and gas. PZP Eco Black and PZP Eco Steel are separated and can be reused without the necessity of removing the additives originally introduced by the tire manufacturer.. Meanwhile, the PZP Eco Gas and PZP Eco Oil can be sold separately or used to produce energy.