Tires Recycling & Decomposition

Historically the bulk of used tires have been disposed of in tire dumps – some legal, some not.  In the USA and worldwide there is a huge, and growing stockpile of these tires.  For example, a recent U.S. E.P.A. report estimates there were some five billion tires stockpiled in the U.S. alone – representing a fraction of the worldwide total of 20 billion.  Each year, in the USA 330 million passenger tires are added to this stockpile.

Disposal and Recycling

Apart from being eyesores, tire dumps have become environmental tragedies when they combust into difficult to extinguish fires and release a noxious mix of gases into the environment.

Tires are composed of a combination of refined natural rubbers, chemical binders and carbon black.  They also contain sulfur, zinc, nylons and steel (between 8 and 15%).  Tires represent a valuable source of raw materials although only small portion of used tires are shredded and recycled – generally with government subsidy – into low value products such as playground mats, as filler for asphalt in road construction ingredient and as base of landfills.  Tire shred has also been used as fuel source (e.g. cement kilns) although most jurisdictions have past laws banning ‘Tire Deprived Fuels’ (TDR).  These laws only add to the available used tire stockpile.

Decomposition Through ‘Traditional’ Pyrolysis

Since the late 1980’s various attempts have been made to decompose and recucle tires into valuable component products through micro wave heating, or more commonly pyrolysis – which is the chemical decomposition of an organic material at elevated temperatures in the absence of oxygen.  The process is used heavily in the chemical industry, for example, to produce charcoal, activated methanol and other chemicals from wood.  To its advantage, pyrolysis is a well understood and therefore useful process.

A main limitation of the technology is the enormous energy required to sustain a pyrolysis reaction (7 times the energy required to bring water to the boiling point).  This energy inefficiency makes pyrolysis an expensive and a significant source of greenhouse gases. 

‘Traditional’ pyrolysis, as well as TiPs, break tires into an oil as well as carbon product.  However, in the case of pyrolysis, the oil produced is a low value ‘bunker fuel’ and the carbon produced is a sludge the requires further processing in order to be made into a saleable product.  Utilizing our TiPs process creates a high value solvent oil with wide applications as an oilfield solvent (see above) and a high quality ‘carbon black’ in a single operational step.

By comparison TiPs tire decomposition requires only minimal outside fuel (at start up) and produces only minimal greenhouse gases.