Car and truck tires are discarded at the rate of about one tire per year per person in America. But this isn't a problem, according to Robert H. Snyder, a chemist who spent 50-plus years in the rubber and tire industry.
"Within a period of perhaps three years, we may be able to conclude that the national scrap tire problem in the United States has been solved," he says. "By the latter part of 1998, we will be reusing scrap tires at the same rate at which they are being generated. At that point, the existing stockpiles (estimated by the Environmental Protection Agency in 1994 at 3 billion tires nationwide) will acquire some value and soon be depleted."
In his book "Scrap Tires Disposal and Reuse," Snyder says the solution to the scrap tire problem will be hastened by the establishment of profitable, commercial scrap tire enterprises and markets. But before this can happen the following should be addressed:
*The "tire jockey." The jockey, who collects used tires from tire dealers for a fee, plays a significant role in determining where used tires wind up - sold as used tires; sold to a recycler, retreader or someone who turns them into fuel; or landfilled.
To make a profit, the jockey tries to avoid landfills with tipping fees. When scrap tire prices become deflated or fees become too high, dishonest "gypsy tire jockeys" will illegally dump tires that can't be sold.
* Recycling tires into other products. This usually involves chopping and sometimes grinding, which can be troublesome because tires contain dissimilar materials.
For example, modern tires are difficult to process because they contain rubber and wire for the steel belts. Fortunately, virtually every tire component has commercial value, provided they can be separated and recovered economically.
* Correct equipment. Rubber compounds are surprisingly abrasive. Just look at a well-traveled highway. A new surface is rough, but after a few years, tires "polish" it smooth. These factors create a need for rugged, expensive, high-maintenance, special processing equipment.
Equipment used to chop tin cans, scrap tires, auto bodies, appliances or steel barrels is virtually useless.
* Tire Derived Fuel (TDF). By far, the biggest use for scrap tires - more than two thirds of all reused tires - is for TDF. The biggest TDF consumers are cement kilns, followed by pulp and paper mills, electric utilities, industrial boilers and dedicated tire-to-energy plants.
There are other interesting applications for processed scrap tires, albeit in smaller quantities, in road construction and repair, including asphalt, crack and joint sealers, road patching and railroad crossings. Unfortunately, there have been problems in using tire chips in highway construction, such as fires that have started in retaining walls and embankments made from tire chips used a subgrade or backfill.
Tires can be applied successfully to:
* rubber mats;
* large agrimats used in horse and cow barns;
* playground mats;
* "playturf" rubber chips; and
* chips for equestrian areas.
Tire chips can replace wood chips used to turn the sludge from sewage plants into a high-grade compost for horticultural use. Chips also can be used as a lightweight aggregrate fill on highways, as a sub-grade thermal insulation to eliminate frost penetration and heaving on gravel roads in cold climates, as backfill behind retaining walls and to replace crushed stone in septic field drainage systems.
Crumb rubber can be used as a soil amendment on golf courses and on football, baseball and soccer fields, or in fishing reefs, parking lot bump stops, landscape timbers, mailbox posts, etc.
Proponents of tire pyrolysis see promise in this destructive distillation that produces a variety of products from liquid petrolem gas and gasoline to steel and silica. However, Snyder questions this process' economic profitability. The main problems are the considerable energy required during pyrolysis and the inability of derived products to compete economically with other sources. For example, tire chips probably are used directly as fuel or in other applications because they have a higher market value than the products that could be produced by pyrolysis from scrap tires.
Finally, government, both federal and state, help in solving the scrap tire problem is needed, Snyder says. This includes state regulations as well as funding for regulation and stockpile cleanup programs.