The world practically runs on pneumatic tires, but getting rid of them is an environmental nightmare.
Apart from playground flooring material, running tracks for athletes and horses and unfashionable footwear, disposing of or reusing tires has proven to be extremely problematic (remember the Osborne artificial reef off Ft Lauderdale, Florida, made from old tires? It became an environmental disaster and had to be removed by the US Military). Now a scientist at the University of Basque Country, Spain, has used the process of pyrolisis to decompose and reuse the left-over components of pneumatic tires.
Because tires have been designed to perform in the toughest conditions, they also resist the elements, which means when the use-by date has expired, a very large percentage of the tire remains intact (albeit useless). Hence, tire’s damaging short- and long-term environmental impacts.
As her PhD thesis, chemist Ms María Felisa Laresgoiti, undertook to study a process of recovering part of the energy and material costs used to create a tire, as well as a method of decomposing the tire. She used pyrolisis to achieve both aims.
Pyrolisis is a sophisticated method of heating in the absence of oxygen. Ms Laresgoiti used a 3.5 liter fixed bed reactor (vertical tubes packed with particles that accelerate the process of reaction) and employed a nitrogen sweep to guarantee the absence of oxygen.
In her study she concluded that at above 500°C and with 30 minutes of reaction time, the organic material within the tire decomposed. The entire decomposition could be separated into liquids (44 percent) and gases (16 percent) – which could be reused as fuels or raw materials – and 44 percent as solid material, such as metals and soot, which remained basically unaltered.