TyGre Tyre Recycling Method Billed as ‘The Ultimate Retread’
The Economist news magazine has referred to the TyGre gassification method of tyre recycling as “the ultimatum retread” in an article published online on 9 August 2010. TyGre, a project developed by nine collaborators including Tubitak Marmara Research Centre in Gebze, Turkey in a European Union-financed endeavour intended to make useful things out of redundant rubber researchers at the sees tyres transformed into silicon carbide by reacting them with sand. The resultant silcon carbide can reportedly fetch up to 10,000 euros ($13,000) a tonne.
Silicon carbide, which is also known as carborundum, is formed when carbon and silicon atoms are arranged in a diamond-like pattern. According to the Economist, on the Mohs scale of mineral hardness, carborundum scores nine or better. Diamonds, for example, score 10.
Here’s how the report described the process: “First, the tyres are gasified, a process which is similar to burning but involves less oxygen. This releases a mixture of hydrogen and carbon monoxide, known as syngas, and leaves a residue of amorphous elemental carbon called carbon black. Tyres also contain sulphur, which is added as part of the process of vulcanisation that makes rubber into a suitably resilient material. Gasification liberates this in its elemental form, making it easy to recover. Burning a tyre, by contrast, produces sulphur dioxide, a noxious pollutant.”
The carbon black is then mixed with sand and the mixture is heated to between 1,400 and 2,100 degrees Celcius in a syngas-fired oven.