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Chipping Makes Old Tires Burn Better
United Power Association, of Elk River, Minn., has burned some 250 tons of old tires in its electric generating furnaces during the last two years and is now preparing to burn more than 2,000 tons of old tires at once in a 50% mixture with coal. Old tires are turned into chips to make them burn better, and to facilitate handling.
The company, which sells electricity to distributors throughout Minnesota, decided to go ahead with a big burn of old tires after tests with a rubber and coal mixture were monitored favorably by the state's pollution control agency.
Wayne Hanson, production engineer, says the chipped/tire rubber which the company uses behaves much like coal when burned, and has about 16,000 btu's per pound, or about twice as many btu's per pound as coal. In the extreme heat of the generating station's furnaces the tires are completely combusted and whatever smoke is left from the tires is removed by pollution control equipment. Steel used in the bead, or in radials, also disappears completely, being oxidized by the extreme heat.
"One problem we've had is that there is less ash left after burning tire rubber than coal. Normally, a layer of ash from the coal protects the fire grates from the heat of the fire. So, because the rubber burns more completely, a partial mixture of coal is necessary when burning rubber," explains Hanson.
He adds that, so far as he knows, United Power Association is one of the first utilities in the country to experiment with tire rubber as fuel but he expects others to follow if further tests continue to prove successful. He notes that there are as many as 4 million tires thrown away in Minnesota alone each year that could yield 40,000 tons of high-grade tire fuel.
Handling is a problem in burning tires, unless they are processed in some way. UPA obtains its tire chips from Schriptek Recovery Systems, Ltd., in La Crosse, Wis. The company recently developed a shredding machine that can tear up even steel-belted tires, bead and all. It makes chips 2 to 3 in. across from any tire up to truck size.
Tim Brady, vice president of marketing for Schriptek, told FARM SHOW there is a strong market for their machine across the country, although he says United Power Association is the first company he's heard of that's burning old tires for fuel. Other companies use various processes to extract the rubber in tires for re-use by manufacturers.
"We take our machine on the road to customers and supply their needs on a regular basis by shredding discarded tires in their area. Other customers buy their own machine," explains Brady. He's excited by the idea of developing small furnaces that can burn old tires. Groups of farmers could buy their own tire-shredding machine, or hire Schriptek to visit on a regular basis. He notes that tire chips are selling for as much as $50 a ton, or about 50 cents for each of the 100 tires in a ton. The machine can also be used to shred wood pallets, tin and other waste products for fuel.
For more information, contact: FARM SHOW Followup, Schriptek Recovery Systems, Ltd., P.O. Box 2105, La Crosse, Wis. 54601 (ph 608 781-1180).

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1982 - Volume #6, Issue #1