SAE R-158-1998 Scrap Tires Disposal and Reuse (To Purchase Call 1-800-854-7179 USA Canada or 303-397-7956 Worldwide).pdf

1、Scrap Tires Disposal and Reuse Robert H. SnyderScrap Tires: Disposal and Reuse Robert H. Snyder Society of Automotive Engineers, Inc. Warrendale, Pa. Copyright 1998 Society of Automotive Engineers, Inc. eISBN: 978-0-7680-3671-8Library of Congress Cataloging-in-Publication Data Snyder, Robert H. Scra

2、p tires: disposal and reuse / Robert H. Snyder. p. cm. Includes bibliographical references (p. ) and index. ISBN 1-56091-682-6 (alk. paper) 1. Waste tires-Management. I. Title. TD797.7.S64 1998 678.320286-dc21 97-46942 CIP Copyright 1998 Society of Automotive Engineers, Inc. 400 Commonwealth Drive W

3、arrendale, PA 15096-0001 U.S.A. Phone: (724) 776-4841 Fax: (724) 776-5760 http:/www.sae.org ISBN 1-56091-682-6 All rights reserved. Printed in the United States of America. Permission to photocopy for internal or personal use, or the internal or personal use of specific clients, is granted by SAE fo

4、r libraries and other users registered with the Copyright Clearance Center (CCC), provided that the base fee of $.50 per page is paid directly to CCC, 222 Rosewood Dr., Danvers, MA 01923. Special requests should be addressed to the SAE Publications Group. 1-56091-682-6/98 $.50. SAE Order No. R-158Ta

5、ble of Contents Preface vii Introduction . ix References xvi Chapter 1 The Problem of Scrap Tires 1 Description of the Problem 1 Tires as a Fire Hazard 2 Health Hazards from Scrap Tires 3 The Origins of Scrap Tires 4 References 8 Chapter 2 The Scrap Tire Collection Process 9 Role of the Tire Jockey

6、9 The Dealer-Jockey Relationship 10 Disposition of Medium-Truck Tires 14 Dual Nature of the Scrap Tire Problem 15 Reference 18 Chapter 3 Tire Processing and Its Problems 19 Difficulties in Chopping Tires 19 Primary Tire Chopping 20 Screening and Sorting of Tire Chips 28 Utility of Coarsely Chopped T

7、ire Chips 29 References 30 iiiScrap Tires: Disposal and Reuse Chapter 4 Further Comminution of Tire Chips 31 Particle Size as Related to Process 31 Problems with Tire Cord and Tire Wire . 32 Ambient Grinding 34 Cryogenic Grinding 35 Wet Grinding 37 Reference . 37 Chapter 5 Engineering Properties and

8、 Value of Tire Chips 39 Unique Properties of Scrap Tires 39 Cost Considerations 41 Perception of the Problem 42 Hierarchy of Uses for Scrap Tires 44 Reference 45 Chapter 6 Fuel Uses of Scrap Tires 47 Characteristics of Tires Burned as Fuel 47 Whole Tires as Boiler Fuels 50 TDF as Supplemental Coal F

9、uel 51 TDF as Wood Supplement 52 TDF in the Portland Cement Industry 53 Reference 56 Chapter 7 Transportation Uses of Scrap Tires 57 Rubber in Asphalt 57 Crumb Rubber in Crack Sealants 61 Crumb Rubber in Repair Membranes 61 Crumb Rubber in Paving Courses 62 ISTEA Mandate on Use of Crumb Rubber in Hi

10、ghway Construction 65 Rubber in Railroad Crossings 67 References . . 70 ivTable of Contents Chapter 8 Mats, Playturf, and Equestrian Uses of Scrap Tires 71 Rubber Mats 71 Agrimats . 73 Rubber Mats for Playground Surfaces 74 Playturf from Scrap Tires 76 Rubber in Equestrian Arenas 78 References 80 Ch

11、apter 9 Scrap Tires in Sewage Sludge Composting and Soil Amendments . 81 Sewage Treatment Plant Sludge 81 Tire Chips Replace Wood Chips in Composting . 82 Effects of Crumb Rubber on Soil . 86 Crumb Rubber as a Soil Amendment 87 References . 93 Chapter 10 Civil Engineering Studies and Applications 95

12、 Use as a Lightweight Aggregate in Fill 95 Use as Subgrade Thermal Insulation 98 Use as Backfill Behind Retaining Walls . 98 Use in Landfills 98 Use in Septic Fields 99 Recent Problems in Using Tire Chips in Highway Construction 100 References 105 Chapter 11 Tire Pyrolysis 107 Description of the Pro

13、cess 107 Feasibility of Tire Pyrolysis 108 References 111 vScrap Tires: Disposal and Reuse Chapter 12 Other Solutions: Fishing Reefs and Molded Rubber-Plastic Blends 113 Scrap Tires in Fishing Reefs 113 Molded Rubber-Plastic Blends 114 References 120 Chapter 13 Scrap Tire Regulations in the United S

14、tates 121 Perception of a National Problem 121 The Need for State Regulation 121 Patterns Among State Regulations . 123 Funding 124 New Programs 125 References 126 Chapter 14 Overview and Projections for the Future 127 Overview of Current Usage 127 Conclusions and Projections 130 References . 134 In

15、dex 135 About the Author 149 viPreface In the early 1970s before any general recognition was given to a national scrap tire problem, the situation was brought to my attention as part of another problem. A lieutenant on the Detroit police force had written a long let- ter to the president of the U.S.

16、 Rubber Company about a prob- lem that was plaguing the police, namely, abandoned vehicles. Every month the Detroit police coped with approximately 2,000 vehicles that had been abandoned and had subsequently become a police problem. The police officers worked with the local car junkies with good suc

17、cess except for two items: scrap tires and upholstery. The lieutenants letter, which asked if we could help him, came to my desk, with the admonition of “Please handle.“ Even 30 years later, I am still trying to “handle“ the problem. In response to the letter, I spent the next few days in the lieute

18、nants company, visiting the depots where the abandoned vehicles were sequestered. The vehicles were kept for six months while the police tried to identify the owners and determine whether the vehicles had been used in a crime. Assuming no answers were found, the vehicles were now ready for the auto

19、junkies, with whom the police had regular dealings. We visited several sites that were typical, admiring the expertise that goes into separating the more valuable residual metal components from those of less value and finally coming face to face with the large piles of scrap upholstery and the scrap

20、 tires that remained mounted on wheels because of high dismounting costs. At that time, the viiScrap Tires: Disposal and Reuse mounted tires were likely to be hauled to a dump and burned, but public opinion was rising in opposition to the practice. The auto upholstery was mostly Saran, originally ch

21、osen because it was nonflammable; however, at this point, the upholstery was cursed with a high scrap cost because it could not be disposed of by burning. This event prompted my interest in the scrap tire problem, an interest that grew steadily and persisted into my retirement. More recently, I am h

22、appy to acknowledge a debt to Norman Emanuel of Baltimore, Maryland, the guru of all tire choppers in terms of depth of experience and technical expertise, for his friend- ship and advice during the past 30 years. I also extend gratitude to Louie and Tim Baker of Baker Rubber. Finally, I express my

23、appreciation for the splendid support that I received from Kuivi, my gracious and lovely wife for 52 years, and from our chil- dren, one of whom developed my affliction and does business as JaiTire Industries, chopping tires in Denver and marketing Crown III nationally as a turfgrass top dressing. R

24、obert H. Snyder February 1997 viiiIntroduction From the beginning of the automotive industry, vehicles have been equipped with rubber tires. It can be argued that the mod- ern automobile would not have been possible without Robert Dunlops invention of the pneumatic tire and its enormous sub- sequent

25、 development. In the 1920s, the average mileage that could be expected from a pneumatic tire was only a few thousand miles, in contrast to the 40,000- to 50,000-mile treadlife expectancy of todays tires. During the 1920s, tires also were much larger. Modern textiles and improved rubber compounds hav

26、e permitted substantial increases in the load-carrying capabilities of tires. During most of the history of the automobile, a scrap tire prob- lem did not exist. The problem began in the early 1960s and has become acute only during the last 15 years. It is a matter of interest and some relevance to

27、understand why this occurred. Prior to World War II, tires were constructed from cotton textile cords, natural rubber, and (then as now) steel wire beads. Natu- ral rubber, as received from the Indies, came in 200-lb bales of highly elastic but nonplastic smoked sheets which are intrac- table in the

28、 rubber factory. Before articles can be shaped and molded from raw natural rubber, the rubber first must undergo substantial processing to reduce it to a limp, plastic state that is suitable for the calendering and extrusion operations required to assemble the raw tire before vulcanization. ixScrap

29、Tires: Disposal and Reuse Calendering is the process in which extended sheets of uniform films are produced by squeezing rubber or plastic between large counterrotating rolls. In extrusion, thick shaped pieces are pre- pared by forcing the material through a die under pressure from a rotating screw.

30、 Vulcanization is the process in which sulfur is combined with rubber or plastic in a chemical operation that links the polymer chains, thereby increasing strength, stability, and elasticity of the polymer. These preparative operations were expensive and time consuming. Fortunately, the processing o

31、f natural rubber compounds could be expedited by the use of sub- stantial amounts of previously vulcanized but reclaimed rubber compounds. Here, reclamation refers to a process by which a vulcanized rubber object is devulcanized or otherwise degraded back to a plastic mass. One of the properties of

32、natural rubber compounds is its ability to slowly devulcanize when heated strongly. In the jargon of the compounder, the natural rubber compounds are said to “revert.“ For tires or other rubber articles in service, this property clearly is a defect; however, this defect becomes an advantage in rub-

33、ber reclaiming. In the devulcanization process, what appears to occur is that some of the polymeric chains in the rubber poly- mer molecule are cleaved, and some of the sulfur cross links are broken. The net effect results in smaller, modified rubber mole- cules that can be recompounded and revulcan

34、ized to produce rubber articles with reasonably good properties, although not as good as those of articles made from virgin rubber. More specifically, this devulcanized rubber compound (reclaimed rubber) can be added in substantial amounts to new natural rub- ber to yield compounds of superior proce

35、ssability and minimal loss of quality. In the face of such obvious value, reclaiming processes were developed to accelerate the reaction and to xIntroduction produce reclaimed rubber of high value at low cost. Prior to the period following World War II, such tires as could be collected economically

36、were collected and reclaimed in hundreds of facilities throughout the United States. All of the major U.S. tire companies operated reclaiming plants. According to annual reports provided by the U.S. Department of Commerce,I-1 291,082 long tons of reclaimed rubber were used in 1943, and as late as 19

37、60 reclaim consumption was 278,703 long tons. The unavailability of natural rubber during World War II neces- sitated the development of synthetic rubber. Initially, this new synthetic rubber was of poor quality and intolerable processability. At the end of World War II, synthetic rubber remained ge

38、nerally inferior to natural rubber. Melvin Mooney, one of the great figures in rubber science and technology, once wrote a sober comparison of the technical quality of early styrene-butadiene rubber (SBR) versus natural rubber and con- cluded that “the properties of SBR bore the same relation to tho

39、se of natural rubber that a hens egg does to that of a stork!“ He was referring primarily to treadwear resistance and cut and tear resistance of compounds of that day. But with continuing devel- opment, the true virtues of SBR in terms of treadwear superior- ity and the absence of the reversion defe

40、ct began to emerge, and synthetic rubber slowly supplanted natural rubber in tires. Of particular importance in the development of synthetic rubber was the commercial benefit of long-range price stability of the synthetic product in comparison to the wild price swings that occurred with natural rubb

41、er. Several times within a decade, the price of natural rubber fluctuated from $0.05/lb to more than $1/lb during one calendar year. These wild price swings in a major commodity whose markets were 10,000 miles distant were intolerable. There were several years when at least one major xiScrap Tires:

42、Disposal and Reuse U.S. tire manufacturer lost more money in rubber inventories than it made in operations. In the continued technical development of synthetic rubber, poly- mer chemists achieved great control of the process and were able to produce SBR of superior processability, which could be fur

43、- ther improved by the addition of cheap petroleum oils at prices of approximately $0.04/lb, in contrast to reclaim at $0.14/lb. Inevitably, rubber reclaiming became a dying industry. In 1996, no commercial operation was reclaiming tire rubber domesti- cally, and the single remaining operator, U.S.

44、Rubber Reclaim- ing Company, reclaims only butyl tubes at the level of approximately 1,500 tons annually.I-2 In tracking the demise of the previously prosperous rubber reclaim- ing business, one other important point must be understood. Even in the heyday of the industry, it was impossible to use re

45、claim in amounts greater than 20% without serious loss of quality. Tires made entirely from reclaim would have been of commercially unsatisfactory quality. Accordingly, it was never possible to reclaim all of the tires discarded in any year and to reuse them by putting them back into that same numbe

46、r of new tires to be pro- duced the following year (i.e., 100% recycling of tires back to tires). However, during the thriving years of the rubber reclaim- ing industry, many articles made from rubber that could also use reclaim are no longer manufactured from rubber today. Modern plastics have repl

47、aced rubber in many large-volume uses. Wire insulation, floor tile, floor mats, garden hose, and other articles were once made chiefly of rubber compounds, and those articles also could employ large amounts of reclaimed rubber. In recent times, polyethylene or polyvinyl chloride (PVC) has replaced r

48、ubber in many of those items. Thus, the corresponding markets for reclaim have disappeared. xiiIntroduction As noted above, the level of use of reclaim in tires has declined drastically. In addition to the technical reasons, one important contributing factor was the decline in the use of snow tires.

49、 Years ago, the average car owner maintained a pair of snow tires, which had to be mounted on the car for the winter and removed in the spring. Often, these snow tires were retreads, and the rubber compounds used in their bulky treads usually contained substan- tial amounts of reclaim. All-season tires have virtually displaced conventional snow tires in the marketplace, with a considerable diminution in reclaim usage. Finally, the adoption of radial tires has played a role in the demise of reclaim markets. The greater tread life of radial tires and enhanced service requirements,