Waving aside tyre incineration

Microwave technology that cleanly converts potentially toxic products such as car tyres into high-quality reusable waste has been developed by a UK company. However, Amat admitted that its system may never be used in this country.

Despite receiving DTI funding for the initial research, the company said government backing for controversial incineration plants has effectively closed the door on its UK commercial ambitions. The process will almost certainly first appear abroad.According to Amat, its process could revolutionise the way substances such as tyre rubber are disposed of by breaking them down using high-frequency radio waves rather than heat, which produces toxic emissions.

The Crewe-based company has also successfully tested its technology with other materials such as plastics and petroleum, as well as the initial application of tyre reprocessing.

Amat’s technology, which it has patented under the name Z3a, bombards the material with microwave energy. By precisely controlling the wave form of the microwaves Amat causes the bonds within compound chains to break and reduces the substance to its original molecular components.

In the case of rubber tyres these include high-grade carbon, which can be sold to rubber companies for reuse, and oil of a high enough quality to power the microwave unit the next time it is used, making it energy self-sufficient. Wire mesh embedded in the tyres can also be recycled.

Because the process relies on microwave rather than thermal energy, the temperature does not reach the extreme levels of heat at which tyres begin to emit toxins.

Dr John Newham, a specialist in environmental chemistry who assessed the Amat process during research at the University of Northumbria, said Z3a represented ‘acompletely novel use of microwave radiation. In essence it is very low-energy pyrolysis but operates to completely different principles from thermal pyrolysis.’

Newham said pyrolysis relies on extreme levels of heat alone to destroy compounds such as rubber. Microwave energy is a far more subtle tool, with ‘many favourable aspects’ in terms of the high quality of the residue and lack of toxins produced. ‘It may well have potential in other areas,’ he said.

With stockpiling of old tyres due to become illegal under EU rules later this year, Amat’s system looked like a technology whose time had come. However, despite successful independent validation of Z3a’s tyre-processing capabilities, Amat said it feared it would never be used in the UK.

Amat received £80,000 of government funding for its research in the form of two DTI Smart awards – alongside £1.2m invested privately by the company’s founders – but is struggling to secure commercial backing in the UK. Peter Skeels, Amat’s managing director and one of the developers of the technology, claimed short-termism had led the government to pursue the cheaper option of incineration.

The Environment Agency is allowing high-temperature pyrolysis of tyres to take place in cement kilns, insisting the process is safe despite concerns of local residents that toxins will leak into the environment.

According to Skeels, the single-track approach has virtually shut out possible sources of funding for those pursuing alternative technologies. ‘It’s blocking what is genuinely a new and exciting way to do things more cleanly and efficiently.’

He said development of a full-scale Z3a unit was likely to happen abroad following interest from Japan and the US.

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