PR0535342 - Laserfiche WebLink

Home Browse Search

scrept.baca a - 9 P24 to track existing and emerging recycling technologies. The scrap tire recycling effort seems to be improving, but at a very slow pace . A major problem appears to be the existing stockpiles of scrap tires . In California, the CIWMB estimated that 33 million tires were stockpiled throughout the State . The CIWMB is currently investigating over 400 illegal tire dump sites containing millions of tires . The national stockpile was pegged at 3 to 4 billion scrap tires . The greatest potential for recycling large quantities of scrap tires lies in power generation and cement manufacturing. An automobile tire contains considerably more energy than an equivalent weight of bituminous coal . United States cement plants and five hundred power plants currently burn bituminous coal . According to CIWMB, tires produce less ash and contain less sulfur than many commonly used types of coal, and with no significant differences in emissions . A power plant that burns 5 . 5 million tires annually produces enough energy to provide power to 15, 000 homes for one year. In the cement manufacturing process, tires are a supplemental fuel source and the ash residues become part of the chemistry of the cement . At the Calaveras Cement Company in Redding, CA, powdered limestone and shale are fed into a rotating kiln. As whole tires are dropped into the furnace they flash into fire . The furnace reaches temperatures of around 2, 600 degrees fahrenheit . As the rock, revolving, roasts, the tires supply not only the heat but also the iron oxide indispensable to cement . The steel wire and belts completely oxidize . The heat causes the limestone ' s calcium carbonate and carbon dioxide to separate, leaving calcium oxide, or quicklime. Then quicklime reacts with silica and alumina (in the shale) to form calcium silicates and aluminates, which leave the kiln as clinker. This clinker is ground with gypsum, making cement . No ash and no slag. In Germany and Japan, about twenty per cent of the fuel for cement plants is whole tires . California has eleven cement plants . Those eleven plants could consume the entire 33 million tire stockpile in one year. According to CIWMB, the cement manufacturing industry could use all of the waste tires generated in the state as well as the existing stockpiles . From an energy perspective, use of tires as a supplemental fuel in cement kilns displaces fossil fuels and results in no wastes and no significant differences in emissions . Cement plants alone could solve the scrap-tire dilemma. There are enough cement plants in the United States to use three billion tires a year. The major obstacles to solving the dilemma appear to reside in regulatory programs, public perceptions and economics . State and regional health and air pollution control agencies need to loosen up on their restrictions, streamline the permitting