Plastics, Rubber, and Paper Recycling - ACS Publications - American

Chapter 20

Scrap Tire Recycling: Regulatory and Market Development Progress 1

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Downloaded by UNIV OF QUEENSLAND on October 8, 2015 | http://pubs.acs.org Publication Date: May 5, 1995 | doi: 10.1021/bk-1995-0609.ch020

John R. Serumgard and Andrew L. Eastman

1Scrap Tire Management Council, 1400 K Street, NW, Washington, DC 20005 Goodyear Tire & Rubber Company, Akron, OH 44316

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The largest problem area for polymer reuse and recycling is the 250 million scrap tires generated annually in the United States. Lacking any possibility of closed loop recycling with this thermoset product, the challenge is to find economically and environmentally sound uses for the tire, whether whole or processed. Since 1990, the beneficial utilization rate for scrap tires has increasedfromless than 11 % to more than 33% of annual generation. Principal methods of utilization are as a high value fuel in several industrial and electric generating applications, the use of ground rubber to modify asphalt paving materials, the use of ground rubber in other products, and the use of whole and processed tires in civil engineering applications. The outlook for expanding these markets is such that by 1998, virtually all newly generated tires will be reused in some manner.

Two hundred and fifty million tires ~ each year, every year — for the foreseeable future will be discarded in the United States. The search for economically and environmentally sound uses for those tires is a major challenge facing both the solid waste management industry and, equally importantly, all segments of the tire industry. Substantial progress is being made in this effort, although there is still a considerable distance to go before the goal of sound utilization of all scrap tires is realized. The efforts to insure proper handling of scrap tires and to expand their markets involve both responsible regulation at the federal and state government levels and development of private and public sector end uses. The Current Scrap Tire Situation Volumes. With tires being scrapped at the rate of nearly 250 million per year, this amounts to roughly one scrap tire for each man woman and child in the country. 0097-6156/95/0609-0237$12.00/0 © 1995 American Chemical Society In Plastics, Rubber, and Paper Recycling; Rader, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1995.


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A state need only look to its population numbers to estimate the number of scrap tires discarded annually. Because all tires are not equal, if the annual generation were converted to passenger tire equivalents, the number would be nearly 350 million, with a total weight of around 3.5 million tons, or slightly more than one and one half percent of the municipal solid waste stream. Annual generation is only part of the management problem. For many years, one of the major disposal options for tires was the scrap pile. In the absence of good markets, most tires went to landfills or to scrap tire stockpiles. Stockpiles, both legal and illegal, can be found in virtually all states. Some began as entrepreneurial dreams in times of energy shocks that tires would be "black gold" and would someday be worth fortunes for their energy value. Other stockpiles grew out of failed recycling ventures that ended up only with piles of tires and no useful end product. And many stockpiles grew through illegal dumping on out of the way land, or in streams or forests. For the nation as a whole, the United States Environmental Protection Agency estimates there are more than 2 billion stockpiled and landfilled scrap tires. 1

Markets. In 1990, some 25 million scrap tires, or approximately 10% of the annual generation rate, had markets. The most significant market was tire-derived fuel, which consumed 95% of the market share. The remaining five percent was split between rubber modified asphalt and civil engineering applications. Over the course of the last four years, markets for scrap tires have more than tripled. By the end of 1994 it is estimated that the equivalent of 160 million passenger tires will have markets, or about 46 % of the total annual generation. Whole or processed tire-derived fuel is still the most significant market, consuming almost 103 million scrap tire equivalents. Other major markets are set forth in the following table: 2

Table I SCRAP TTRE REUSE/RECYCLING

as of December 31,1994 USE

Energy Recovery Ground Rubber (Asphalt (Other Fabricated Products Civil Engineering Agriculture Export Total Landfill/Stockpile/Monofill

PERCENT AGE

PASSENGER TIRE EQUIVALENT (000,000)

29% 6%

103 20

2.6 3.4 4.6 2.4 1% 3% 46% 54%

11) 16 8 3 10 350

9)

In Plastics, Rubber, and Paper Recycling; Rader, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1995.

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Scrap Tire Recycling

Projections by the Scrap Tire Management Council show that by the 1997 1998 timeframe,virtually all annually generated scrap tires will have markets. The three major markets are projected to be whole or processed tire-derived fuel (TDF), rubber-modified asphalt and civil engineering. The remainder should be consumed by a variety of innovative technologies. 3


The Regulatory Picture As a solid waste, scrap tires are regulated principally at the state level. There are no specific scrap tire provisions in the Resource Conservation and Recovery Act, the principal federal solid waste law. Currently 48 of the 50 states have some specific legislation or regulations dealing with scrap tires, Delaware and Alaska being the last two holdouts. At last count, 37 states have enacted specific scrap tire legislation. The balance of the states regulating scrap tires do so under broad solid waste laws. These laws and regulations often have many common features. Among the most common features are: 1. Regulation of the manner of disposing of tires in landfills or at stockpiles; 2 Regulations, including permitting requirements, for scrap tire haulers, processors and end users; 3. Financial responsibility requirements for sites at which scrap tires are collected, stored or processed; 4. Provisions for market development, including financial assistance to end use markets or new entrants into the scrap tire business; 5. Provision forfinancialsupport for implementation of the state's scrap tire management program, supported by a state fee or tax at some point in vehicle or tire ownership; and. 6. Provision for cleanup of scrap tire piles. The actual experiences within several states demonstrate that it is possible to positively affect the management and use of scrap tires. In Oregon, a state law was passed in 1985, just the second state to pass a scrap tire law. By 1992, the state had been successful in cleaning up its scrap tire stockpiles and the private sector had developed markets for all of the newly generated scrap tires, these being principally fuel markets. As a result, the state allowed its special fee for its scrap tire program to expire. Minnesota was thefirststate to enact scrap tire legislation in 1984, and it has reached the point where it is in the final stages of stockpile cleanup, and has functioning markets for all its new scrap tires. In the process Minnesota has cleaned up more than 12 million stockpiled tires. Illinois has had an aggressive program to assist in developing scrap tire markets, and has seen several major markets develop with state assistance. In Illinois, the use of state funds in the developmental stages of several projects was money well spent when the projects came to operational state.



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Where states have focused their attention on identifying, promoting and assisting end use markets, such as in the states just mentioned and in others such as Florida, California, Georgia, and others, steady progress is being made. Some states, however, have taken a different attack, focusing instead on assumption of the burden of basic scrap tire management, and on intermediate processing. In these states, principally Texas and Oklahoma, the development of end use markets has lagged. The Texas program provides payment to processors who collect tires from dealers and process the tires into shreds. The processors have until January 1, 1996 to establish that they have markets for their shreds. As a result, the state now has more than 40 million shredded tires in stockpiles, and very few end use markets. Oklahoma has a similar, if smaller scale problem. The tire industry has consistently supported sound scrap tire legislation at both the state and federal level to ensure that scrap tires are managed in environmentally responsible ways. Equally importantly, the tire industry has been a consistent participant in the effort to find appropriate markets for scrap tires, and to promote the expansion of those markets. Markets for Scrap Tires Any solutions must address the various sources of scrap tires. Almost 95% are returned by the consumer to thousands of dealers across the country when worn out tires are replaced by new ones. Of the alternatives, immediate recycling/recovery of scrap tire through viable non-subsidized markets is the industry's priority. Feeding stockpiles and landfills — even with shredded materials ~ provides few benefits. The key tofindingsolutions to the scrap tire dilemma is the same as it is for any number of other products which society would like to see reused: it's markets, markets, markets. In addressing any solid waste issue, there is a national public policy which favors consideration of a hierarchy of alternatives. This hierarchy is the now familiar mantra of Reduce, Reuse, Recycle, Recover, Dispose. For tires, this hierarchy has certain limitations and opportunities. These can be summarized as follows: Reduce. Thefirstmost desirable alternative is source reduction. In the case of tires, the objective is to reduces the number of tires that enter the waste stream. The tire industry's efforts during the past twenty years to improve tire life has doubled the mileage and life of a typical passenger tire. Reuse. The next best alternative is to reuse the tire. The tire casing is retreaded or manufactured into miscellaneous products. Significant improvements in retreading permit the average truck tire to be retreaded 2 or 3 times. Airplane tires are retreaded up to 12 times. The casing is often used for miscellaneous products such as muffler hangers and snow blower paddles. Unfortunately, this market represents a small part of the annual take-off and is slow to expand. Grindings or


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crumb rubberfromtread and sidewalls can be used as a filler for rubber or plastics products and asphalt. Recycle. True recycling of vulcanized rubber products through devulcanization, while technically possible in the laboratory, is highly impractical for large scale use.


Recovery. Energy recovery is the best alternative today. There are significant economic and environmental reasons to explain why this alternative is the current best solution. Disposal. Finally, when tires are shredded, they do not create an environmental problem in a landfill or monofill. A recent study by Radian Consultants verified that scrap tires do not create hazardous leachate. Shredded tires take up less space than whole tires and almost eliminate thefirehazard. In 1994 several regions of the United States will have competitive environmentally sound and economically viable markets that did not exist just a few years before. The additional markets will create competition which will lower scrap tire management costs. There are several sound markets for scrap tires. The largest current and potential market is the use of scrap tires as fuel, in markets such as electrical generation, industrial boilers, and particularly in energy intensive processes such as cement manufacturing. Ground rubberfromtires isfindingits way into new applications every day,froman additive to asphalt paving materials, to a wide variety of new products such as flooring and sneakers. Shredded tires are being used as a lightweight fill material in civil engineering applications. Cut tires are used to produce many useful products, including equipment for the commercial fishing industry Tire-Derived Fuel. Tire Derived Fuel, either as whole tires or processed into a chip, is the largest single current and potential market for scrap tires. There are several advantages to using scrap tires in place of most types of coal. Whole scrap tires average about 15,000 Btu per pound. Most coal is in the range of 12,000 Btu per pound. Less carbon dioxide is released to the atmosphere since scrap-tire fuel has more hydrogen than found in coal. NOx is reduced because secondary burning of the carbon in tires occurs, and less organic nitrogen exists in tires than in most coals. Additionally, there is less sulfur in tires than in most coals. Cement kilns are a particularly goodfitwith tires. As of July, 1994, 24 kilns were using tires on a regular basis, another 13 had conducted test burns and an additional 29 kilns were considering using tires. In cement kilns, tires replace up to 20 percent of the total required fuel. The feed systems for whole tires and TDF are relatively inexpensive. A big advantage of using scrap tires in cement kilns is there is no solid waste disposal. The tire is completely consumed and becomes part of thefinalproduct of the kiln called clinker. The clinker is ground with gypsum and the resulting product is Portland cement. Whole passenger tires 4



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can be used as well as coarse tire shreds. Additional success stories in Europe and Japan support the use of scrap tire in cement kilns. Pulp and paper mills in virtually every section of the US are using tires. Paper manufactures that use stoker grate boilers combine TDF with the wood waste they burn - bark and sawdust - to produce steam. The TDF improves the combustion efficiency and replaces fossil fuels. Scrap tires can be used infivedifferent types of boilers used in electric generation - liquid slagging bottom, cyclone, fluidized bed, stoker grate, and dedicated tire boilers. The use of tires in liquid slagging bottom boilers was pioneered by the Goodyear Tire & Rubber Company and further developed by the Ohio Edison Co. at a facility in Toronto, OH. Nearly 50 boilers of this type are currently operational in the US and are potential markets for scrap tire fuel. Several utilities are using tires in various cyclone, fluidized bed and stoker grate boilers. Only two dedicated tires-only plants are operating, although the technology is environmentally sound and the performance is proven. The drawback is the heavy investment needed. One area of concern is with the potential air emissions from using tires as a fuel. Rather than presenting a problem, extensive emissions testing has shown that the use of tires to replace a portion of coal results in reduced emissions. One example is a test conducted at a Monsanto plant in Sauget, IL. Scrap tires were used to generate steam for electricity generation with 2 inch x 2 inch TDF replacing 20 percent of the plant's coal. The test results proved that TDF is an environmentally sound fuel. Particulate was reduced through lower ash. Volatile organic compound reductions were attributed to TDFs increased volatility when compared to coal, Nitrogen oxide was reduced through reburning. Chlorine reduction was attributed to tires having nearly undetectable levels of chlorine. Sulfur increased slightly because low-sulfur coal was used at the facility. An increased presence of carbon monoxide was corrected after the test by adjusting the TDF chip size and the fuel-to-air mixture ratio. Other metals, such as lead, mercury and cadmium, present when coal is the only fuel, were reduced during the supplement test. Furthermore, the test found that fiirans and dioxins were nondetectable. The main components of fuel arefixedcarbon and hydrogen-based material. Carbon, when burned, creates carbon dioxide (CO2) which is targeted as a major contributor to the greenhouse effect that causes global warming. Coal contains twice the fixed carbon that is in TDF. Conversely, TDF contains much more hydrogen based material than coal. Because TDF has less carbon and more hydrogen than coal, TDF burns much cleaner and hotter, and has over 20 percent more heat value, yet creates less C0 . A fuel potential which has not been developed to date in the US is the use of scrap tire shreds in iron foundries. As in cement kilns, the steel in the tires becomes one of the raw materials required in the foundry operations. The foundries, however, are not as limited with regard to the amount of steel that can be consumed. This technology has an excellent potential to handle truck tires. 3

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Many additional fuel users are expected to be on stream by 1997. Capacity to handle the majority of the scrap tire take-off will exist by this time. In many areas of the country, the capacity will exist to make significant reductions in the tire piles. The competition that develops will be favorable to disposal costs and will weed out noncompetitive markets. Growth in tire usage has also increased in other areas. In many of theses cases, subsidies and legislation have played an important role in developing these markets. Nonetheless, usage in these areas has increased, and all of these options combine to help address the scrap tire problem. Civil engineering uses have increased primarily in the area of highway construction. Tire shreds used as lightweight fill have gained acceptance and will be further driven by the asphalt rubber mandate in the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). Whole tires have been used on some projects to form walls and barriers as part of road projects. Soil modifiers are gaining acceptance and use in athletic fields. California, Florida and Arizona are the most active in promoting the use of crumb rubber in asphalt. Most states are running tests to decide how to deal with the mandate of ISTEA. Section 1038 of ISTEA requires that Crumb Rubber Modifier (CRM) for asphalt paving be used in a percentage of each states roads constructed using federal funds. Studies required by the Act were released in 1993. State governors and others challenged the wisdom of the mandate, and Congress chose to delay its implementation. Changes to the law are being proposed to allow wider use of scrap tire rubber in road construction and to delay implementation until 1995. The cost of using crumb rubber is a major drawback. Consistent improvements in test results, reduction in pavement thickness and market volume increases could reduce costs. However there is only limited evidence of this in the last several years. This continues to be a technology that should continue to be developed and utilized where found to be cost effective.. Laws that mandate scrap tire technology, however, interfere with development of free market solutions. Crumb rubber in plastics is being driven by many recycling entrepreneurs, In general, this material enhances the economics more than the quality of the end product. Finally, fabricated productsfromscrap tires continues to show slow growth; however, entrepreneurs are looking for conventional (non-radial) tires to fill their production requirements. Some believe that scrap tires could be reused in new tires in quantities of 5 percent or more. However, there is a serious problem in this concept since ground rubberfromscrap tires is not chemically the same as natural rubber or synthetic rubber. In the grinding process, the rubber is broken down, but no chemically combined sulfur has been removed. The rubber has not been devulcanized. An analogy can be made with baked bread. Yeast and flour cannot be removed from the final product and reused again. Old bread cannot be recycled into new bread. Reclaim or ground material used as afillerin tires causes lower tensile strength, heat buildup and oxidative aging. Therefore, in a new tire, for each 6


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percent of reclaim that is used, there is approximately a 1 percent reduction in tread life. The rolling resistance of a tire containing reclaim is increased, which results in lower fuel economy. Also there is increased lug cracking in large tires. The conclusion — these use of reclaim rubber in new tires is very limited.


Conclusion The tire industry continues to work at all levels to find balanced solutions to the scrap tire issue. This includes working with legislators and regulators at the federal, state and local level on a nearly continuous basis. In addition, extensive efforts continue to promote sound, effective markets. Using scrap tires for fuels is a true win/win opportunity. Overall, solid waste and air emissions are reduced, natural resources are conserved, and energy independence is enhanced. In most cases, it is the cost effective solution. There are many viable, higher uses for scrap tires that exist today and will evolve in the future. Each should be developed, even if individually it does not have a major impact on the waste stream. Together they will. Support must be given to existing technologies. As other solutions develop, they will be encouraged. The tire industry is acting now to enable scrap tires to be handled in an environmentally sound way at the lowest cost to the tire consumer. References 1. 2. 3. 4. 5. 6.

U.S. Environmental Protection Agency, Markets for Scrap Tires, EPA/530SW-90-074B, 1991. A.T. Kearney, Scrap Tire Use/Disposal Study, Scrap Tire Management Council, 1990. A.T. Kearney, Scrap Tire Use/Disposal Study, Scrap Tire Management Council, 1992. Malcolm Pirnie, Air Emissions Associated with the Combustion of Scrap Tires for Energy Recovery, Ohio Air Quality Development Authority, 1991. U.S. Environmental Protection Agency, Burning Tires for Fuel and Tire Pyrolysis, EPA-450/3-91-024, 1991. Federal Highway Administration, State of the Practice - Design and Construction of Asphalt Paving Materials with Crumb Rubber Modifier, 1992.

RECEIVED May 2,

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Plastics, Rubber, and Paper Recycling - ACS Publications - American

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