Good year for tire recovery

Diversion of tires from landfills increased substantially in 1995, reflecting the diversity of end uses being developed.

EACH person in the United States generates about one scrap tire per year, totaling 250 million scrap tires annually, according to the Scrap Tire Management Council (STMC). The good news is that tire recovery continues to rise at a rapid pace. The Council notes that 174.5 million (69 percent) of the 253 million tires that became scrap in 1995 were recovered, an increase of 26 percent from 1994. "This new level of demand is truly amazing when you consider that as recently as 1990, market demand for scrap tires was a mere 11 percent of the total number generated annually," says Michael Blumenthal, STMC's executive director.

Most recovered scrap tires are shredded to generate tire-derived fuel (TDF) for electric utilities, pulp and paper mills, power plants and cement kilns. From 1994 to 1995, the number of scrap tires used for TDF increased from 101 million to 130 million, and is expected to rise to 185 million by 1997. The remaining 44.5 million scrap tires recovered in 1995 were handled as follows: 15 million exported; 12 million used for road fill, landfill cover, erosion control and other civil engineering applications; eight million in punched and stamped products; six million in ground rubber; 2.5 million in agricultural applications; and one million in miscellaneous uses. From 1994 to 1995, civil engineering applications and ground rubber uses increased by 33 percent. The only use which declined in 1995 was pyrolysis, a process to thermally decompose scrap tires into steel, gas, oil, char and other products. The lack of markets for pyrolysis by-products led to the closure of plants and demonstration facilities.

TDF MARKETER

Tire Tech Environmental Systems of Muscatine, Iowa, is one of many companies producing tire chips for TDF. In June,1995, the company began a seven year contract with a private processing plant that burns 800 tons of coal each day. TDF is becoming increasingly popular as a replacement for coal, because it has a higher heating value (more BTUs per pound) and is generally lower in sulphur and ash. To meet its end user's requirements, Tire Tech grinds 25,000 tires weekly into chips. The company collects tires from Iowa, Illinois, Wisconsin, Mississippi, South Dakota and Minnesota in leased trucks and 24-foot vans. Tire Tech charges customers by the ton, and gives their larger suppliers a bulk discount. A million dollar shredder grinds 2,000 automobile tires or 750 truck tires per hour. The firm currently has 22 employees, and expects to double that number this year.

GROUND RUBBER PRODUCTS

American Tire Recyclers (ATR) is Florida's largest ground rubber producer. ATR's vice president, Tiffany Hughes, says the company processed more than 1.2 million tires in 1994 and 1.5 million in 1995. Tires are collected in trailers and fed by conveyors into ATR's processing plant. They are debeaded (steel beads removed from the sidewalls) and shredded into four by six inch strips. A second shredding step results in two inch minus chips. Ninety-nine percent of the steel is removed by putting the pieces through two grinders and four drum magnets; the steel is sold to a Tampa recycler. The chips are ground to sizes ranging from a three-eighth inch crumb to a fiber-free, minus 40 mesh (rubber that passes through a screen with 40 holes per linear inch "about the size of a Sweet and Low granule," notes Hughes).

ATR's line of ground rubber products includes surfaces for horse arenas, playgrounds and parking lots, as well as mulches, highway additives and a soil amendment for sports fields. Equestri-Foot, a surface topping made of irregularly shaped, wire-free tire rubber is used in both indoor and outdoor horse arenas. Fiber reinforced ground coverings are used for landscaping, parking lots and driveways. Sports Turf, a ground covering of one-quarter inch rubber chips for playground areas has two layers, an undercoat of granulated and foam rubber covered with a layer of granulated virgin rubber. To prevent clothes and skin from being stained, the carbon in the rubber is sealed through vulcanization.

ATR also produces Rebound, a soil amendment composed of equal parts of crumb rubber and composted yard trimmings which is being used on approximately 20 sports fields and parks in Florida and Georgia. The rubber has a memory, so it's great as a shock absorber," says Hughes. "It's also porous so water and air can get into the soil, and the ground doesn't become compacted."

COMPOST BULKING AGENT

Eastern Iowa Tire Recyclers, Inc. in Muscatine, Iowa, supplies rubber tire chips to the municipally owned compost site in Davenport, Iowa, where they are used as a bulking agent. One part rubber chips and two parts hardwood chips are mixed with one part biosolids and a small amount of yard trimmings, says Scott Plett, site manager. Rubber chips were introduced into the mix (and the quantity of wood chips was reduced accordingly) in August, 1995. Materials are composted using aerated static piles in an enclosed structure for approximately 21 days. The compost is screened to remove the wood and rubber chips, which are reused as bulking agents. "The rubber chips are initially more expensive, but they don't break down as quickly as wood chips," says Plett. "The wood chips will only last in three or four piles, but we expect the rubber chips to last for a year before they become brittle and pieces start to break off."

Davenport initially purchased 1,500 tons of rubber chips at $35/ton delivered. Wood chip utilization has been reduced from 90 tons/week, at $25/ton delivered, to 60 tons/week by substituting rubber chips.

REGIONAL MARKETS

Two companies have capitalized on their geographical locations to produce specialized products for local markets. F&B Enterprises, located in New Bedford, Massachusetts, was founded in the early 1970s to buy, repair and sell used truck tires. Coowner Thomas Ferreira learned that local operators of commercial fishing boats were having problems with boat parts such as rollers and chafing gear wearing out, and FB began manufacturing the parts out of recycled rubber. The company then expanded into making marine fenders from recycled rubber for ships, docks, tugs, barges, wharves, pilings, and oil rigs, as well as cutting rubber strips from passenger car tires to repair lobster traps.

F&B also manufactures rubberized wear pads for snowplows used to clear airport runways and equipment in transfer stations. Rubber pads, made by laminating die cut pieces of scrap earth mover tires together, are designed to protect concrete floors and surfaces from the wear and tear caused by commonly used steel blades.

Palmer Shredding, Inc. is taking advantage of its location in rural Ferrisburg, Vermont, to make cow mattresses and cow bedding for dairy farms. "We're in the middle of agricultural country here," notes owner Nate Palmer, "and we need local markets to make our business fly, so cow bedding is a logical product." The company is shredding tires into quarter-inch rubber chips, which are stuffed into bags made of a geotextile fabric. The bags can be sized to cover an entire barn floor, or an individual stall.

Two years ago, Palmer acquired an out of commission rubber processing plant located in Andover, Massachusetts, at a fraction of its original $2 million cost. Palmer has been dismantling the mill and transporting it up to Vermont in pieces since July, 1995. He says that he expects the mill to be up and running in March, 1996. The mill is designed to process 700 to 800 tires/hour to produce a two-inch chip, 250 tires/hour to produce a quarter-inch chip, and 200/hour to make a minus 10 to minus 40 mesh chip. Several local haulers collect tires for Palmer, both within and outside of Vermont. Palmer charges 50 cents for an individual tire, and $40 to $50/ton for a large trailer load.

Whole and shredded scrap tires are used in a variety of civil engineering applications. Dodger Enterprises of Fort Dodge, Iowa collects scrap tires from four states to make different products. The company creates tire pipe by banding groups of truck tires together with strips of half-inch steel. The pipe is used for crossings, culverts, drainage, and grain ventilation. According to company representative Ernie Kersten, tire pipe structures are less expensive than concrete and steel structures, and are strong enough to be driven over by heavy vehicles. "We drove an excavator weighing 22 tons over an 1,100 foot section of truck tire pipe, and the pipe did not fail," says Kersten.

Dodger Enterprises also shreds scrap truck tires into chunks ranging from six to 24 inches, used for fill in embankments, around basement walls and over tire pipes. "Rings" and "planter boxes" from tire sidewalls are placed on slopes, covered with soil and seeded at Iowa's Fort Dodge Airport where heavy surface runoff has washed away the ground cover.

RESEARCHING NEW USES

Scrap tire companies are working with university researchers to develop civil engineering applications. Iowa State professors Bruce Kjartanson and Bob Lohnes have received a grant to develop design specifications for the tire pipe and shredded materials produced by Dodger Enterprises. Dana N. Humphrey, a civil engineer at University of Maine, has been testing the suitability of using layers of tire chips in place of gravel as a fill material for road construction. "Tire chips are half the weight of gravel so they don't sink into weak soil, and are eight times better as an insulator than gravel, which can help to prevent frost heaves from forming on roads."

The scrap tire industry expects markets for products to continue to grow in 1996, although not at the rapid pace that occurred in 1995. "It is not unreasonable that we will have demand for 75 percent of all the scrap tires generated by the end of 1996," says John Serumgard, chair of the STMC. -M.F.