New from old

Old tires can be devulcanized

More than one billion old tires are produced every year. In view of this huge quantity, increased material recycling is not only desirable but is also eminently important for reasons of resource preservation. A share of today’s waste tires are ground down and used as a floor covering on playgrounds and sports fields, for example. However, the majority are burnt to generate energy. Up to now, it has not been possible to recycle the vulcanized material to produce new tires – up to now.

This has now been disproved by a Canadian company. And the American colleagues from Leistritz Advanced Technologies Corp./BU Extrusion played a major role in this.


The company has developed an eco-friendly devulcanization method that allows old tires to be recycled and therefore produce a new, versatile and high-quality rubber material. Leistritz is also part of the success story as an exclusive test and licensing partner: vulcanized rubber is for the first time transformed into a thermoplastic state. 100% of the shredded old tires is added to the extruder as ground material. After melting, super-critical carbon dioxide is fed to the process. The resulting melt is packed as granules or in endless strips and can then be used to produce new car tires. What makes this process special is that no devulcanization or chemical solvents are added. 99% of the material is thus transformed. This is the only known, eco-friendly technology that can reverse the vulcanization effect.



is a chemical-technical process by which long-chain rubber molecules are cross-linked by sulfur bridges. The plastic properties of the rubber are thus lost and an elastic state is achieved. The result is a long-life rubber product – perfect to produce tires. The problem then is that vulcanized rubber cannot be easily returned to its constituent parts.

Leistritz Aktiengesellschaft