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RECYCLING
USED TIRES RECYCLING |
Currently, less than 5% of tires worldwide are being recycled and the use of tires as alternative energy fuel presents environmental challenges. There is currently no viable solution to the scrap tire problem. Since tires have no positive sale value the illegal dumping of tires is on the rise.
As a rule of thumb, the scrap tire generation in industrialized countries is approximately one passenger car tire per capita per year. Each tire contains approx.: 85% rubber, 12% steel and 3 % fiber. There are at this time in the world billions of tires that have to be disposed of. While scrap tires represent less than 2% of the total solid waste stream, their disposal is a growing complex problem.
Landfills. Most of the scrap tires (over 75%) are landfilled. Burying whole tires, is not a good disposal option though because tires are resistant to compaction and take up a disproportionate amount of space. In some landfills, methane gas, given off by decaying waste, collects in the cavities of tires, causing them to float to the surface, becoming a potential breeding ground for mosquitoes and rats.
Stockpiling. Roughly 10% of scrap tires are stockpiled in anticipation of finding a future use. This presents a high fire hazard and the clean up cost of tire fires is estimated to be greater than 10 times the cost of tire pile abatement. (Not taking into account the toxic chemicals released).
Recycling. Technological developments over the past few decades have resulted in higher quality tires that meet tougher safety and performance standards, and have longer life spans. At the same time, reclaiming rubber from scrap tires so it can be used again in the production of new tires has become more difficult due to their complex chemistry.
The best use for worn tires is rethreading which currently diverts an estimated 10 -15% from the waste stream. (each rethreaded tire, saves approx. 4 gallons of oil). The rethreading of passenger tires, however, has declined over the last 15 years because the cost of new tires is comparable to quality retreads, and the public perceives the retreads as of poorer quality.
Incineration. While not environmentally sound, incineration of whole or shredded tires is currently used to recover energy. (In the U.S. 9% of scrap tires are presently burned for energy). Scrap tires have about 10% more heat value by weight than coal and burn comparatively cleaner. Tire derived fuel is used in Japan, the U.S., and Europe, and the demand is expected to grow. The environmental consequences are the release of toxic emissions recognized carcinogens: volatile organic chemicals such as benzene, chloroform, 1,2 dichloroethane, methylene chloride and metals such as lead, mercury, chromium and zinc.
Recently, granulated rubber, (known as crumb rubber) has been produced. Tires are ground they can be frozen and shattered. The rubber, steel and fiber is then separated out using screens, magnets and density techniques. Crumb rubber is used as a substitute for virgin rubber or, the main use is as additive in asphalt cement for paving roads. Experts say, however that the long term performance of the product has not been evaluated, including the particle emissions resulting from the wear and tear of the pavement and the recyclability of the end product.
Pyrolysis is the thermal decomposition of an organic material under the exclusion of ambient oxygen. The typical products of scrap tire pyrolysis are: hydrocarbon gases and oils, low grade carbon black and steel. Pyrolysis plays only a marginal role in the scrap tire industry and there seems to be no economically viable pyrolysis process in operation today.
The new technology secured by Lion Energy allows the integration of recycled rubber in a large range of high quality construction materials through an environmentally clean process.
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