Pyrolysis of scrap tires

B. L. SchuJman and P. A. White, "Pyrolysis of Scrap Tires Using the Tosco-11 Process— Progress Report," ACS Symposium Series No. 76, American Chemical Society, Washington, D.C., 1978. 

Pyrolysis of scrap tires was studied by several mbber, oil, and carbon black industries [14]. Pyrolysis, also known as thermal cracking is a process in which polymer molecules are heated in partial or total absence of air, until they fragment into several smaller, dissimilar, random-sized molecules of alcohols, hydrocarbons, and others. The pyrolysis temperature used is in the range of 500°C-700°C. Moreover, maintenance of partial vacuum during pyrolysis in reactors lowered the economy of the process. Several patents were issued for the pyrolysis of worn out tires to yield cmde oil, monomers, and carbon black in economic ways [15-18]. The major drawback of chemical recycling is that the value of the output is normally low and the mixed oils, gases, and carbon black obtained by pyrolysis cannot compete with similar products from natural oil. Pyrolyzing plant produces toxic wastewater as a by-product of the operation [19]. 

If markets for char cannot be developed, the char becomes a major solid waste problem. Analysis of char from the pyrolysis of scrap tires does not indicate a problem with hazardous materials.4 However if it must be disposed of in a landfill, the char should be collected in plastic bags and shipped and disposed of in steel drums to prevent additional fugitive emissions during transportation and disposal. 

Schulman, B.L., P.A. White. Pyrolysis of Scrap Tires Using the Tosco II Process. American Chemical Society 0-8418-0434 9/78/47-076-274. September, 1978. 

The book is presented in two parts. Part I covers the problems associated with scrap tires and identifies existing and potential source reduction and utilization methods that may be effective in solving the tire problem. Barriers to increased utilization and options for removing the barriers are identified and evaluated. Part II provides information on the use of whole, scrap tires and tire-derived-fuel (TDF) as combustion fuel, and on the pyrolysis of scrap tires. The use of whole tires and TDF as a primary fuel is discussed for dedicated tire-to-energy facilities. The use of whole tires and TDF as a supplemental fuel is discussed for cement manufacturing plants, electric utilities, pulp and paper mills, and other industrial processes. The focus of Part II is on the impact of burning whole tires and TDF on air emissions. The information in the book is from the following documents ... 

Pyrolysis of scrap tires gives as major products, gas, oil, and residue. The gas is the result of thermal cracking and dehydrogenation. The oil derives from extender oils used in the compounding of the vulcanizates as well as from the depolymerization fragments from the rubber. The residue represents recovered carbon black as well as any inorganic material used in the fabrication of the original rubber. 

During the last 20 years, significant research has been carried out and various pyrolysis processes have been developed [212-214]. However, despite this progress, pyrolysis of scrap tires is done on a limited scale. This is mainly due to the absence of a wide market for the oil and the carbon black derived by means of the pyrolysis process. 

An unusual feed obtained by pyrolysis of scrap tires was tested by Ucar et At 623 K and 7 MPa of H2, the AC was active for HDS and HCR. However, the activity was significantly enhanced after the addition of active metals to the AC. 

Merchant, A.A., and Petrich, M.A., Pyrolysis of scrap tires and conversion of chars to activated carbon, AlChE J.,39(8), 1370-1376(1993). 

Pyrolysis - [MANGANESE COMPOUNDS] (Vol 15) -in batteries [BATTERIES - PRIMARY CELLS] (Vol 3) -of benzene [BENZENE] (Vol 4) -of esters [ESTERS, ORGANIC] (Vol 9) -of lignite [LIGNITE AND BROWN COAL] (Vol 15) -of scrap tires [RECYCLING - RUBBER] (Vol 21)... 

Fluidized sand beds are surprisingly insensitive to the unit size of the feed material. Pieces of scrap tires up to a weight of 2.7 kg each were fed and quantitatively pyrolyzed. These results offer the perspective for a pyrolysis process for scrap tyres without prior size reduction. Most pyrolysis processes use feed crushed to a 200-20 nun size which involves considerable expense [9], Successful pyrolysis experiments in an indirectly heated rotary kiln have been conducted by Kobe Steel [3]. 

H. W. Schnecko, Pyrolysis of used tires, Chem. Ing. Techn., 48, 443-447 (1976). W. Kaminsky, Pyrolysis of plastic waste and scrap tyres in a fluid bed reactor. Resource Recovery Conserv., 5, 205-216 (1980). 

The actual plant will process T 000 tons of scrap tires collected each year by Automotive Tire Trading Association. The plant is funded by several public agencies such as Kikai Shinko Kyokai (Japan Society for the Promotion of Machinery Industry), Clean Japan Center, Hyogo Shigen Sairiyo Jigyo-dan (Hyogo Prefecture Resource Recovery Incorporation). Fig. 4 shows a view of the pyrolysis plant and Fig. 5 is the layout of the plant. 

Co-disposal of Scrap Tire and Refuse. The experiment was carried out with shreded tires mixed with municipal refuse. The composition of the samples of produced gases from pyrolysis furnace are as shown in Table VI. 

Part I of this book discusses markets for scrap tires including major issues of the current problem, market barriers, and options for dealing with the waste tire problem. Part II discusses using tires for fuel and tire pyrolysis. This part focuses on use of scrap tires as a primary fuel for dedicated tire-to-energy facilities and as a supplemental fuel for cement pants, electric utilities, pulp and paper mils, and other industrial processes... 

Pyrolysis, or the destructive distillation of scrap tires, has been proposed as a means of converting scrap tires to useful products. Pyrolysis in the absence of air is not a new technique. It was, and still remains, used as a powerful investigative tool. 

Pyrolysis of scrap rubber gives oil and char, from which carbon black can be obtained. The process has been tested on a small scale, more often on a laboratory scale, and sometimes on a large scale, and seems promising [57], in spite of the high quality required for the carbon black used to reinforce rubber, especially in tires [56]. 

Combustion of scrap tires and, for that matter, any pulverized fuels including coal, coke, or biomass proceeds in two phases. First, the organic solid polymer undergoes pyrolysis upon reaching a temperature of about 250-300°C to release the volatile matter and solid residue (char). Second, these volatiles and char undergo combustion (Figure 6.3). 

Nippon Zeon estimated that the break-even cost of its tire pyrolysis pilot plant was 0.25 per tire (29,30). One study indicates that pyrolysis of tires and other polymers should be considered as a means for disposing of scrap within environmental constraints. A plant processing 81,000 t/yr of scrap could be profitable, based on sales of reclaimed products (31). 

Scrap tire pyrolysis, 22 466-467 Scrap tire regulations, 22 462 Scrap tire utilization projects, goal of, 22 478... 

The U.S. Environmental Protection Agency s Office of Solid Waste recently produced a report entitled "Markets for Scrap Tires", which summarizes the barriers to development of TDF markets for dedicated tire-to-energy facilities, other utility facilities, the cement industry, the pulp and paper industry, and pyrolysis facilities. Table 1-4 summarizes the reported barriers. 

The only raw material required for most tire pyrolysis processes is scrap tires. Some processors purchase and use whole tires, while others chip whole tires into two inch pieces, or purchase the tires already chipped. Conrad uses a local tire chipper to shred whole tires to a 2-inch size, wire-in, for their use. The tire chipper, who works on Conrad property, receives a tipping fee for collecting the tires, and provides the TDF to Conrad free of charge. 

In 1983, the U.S. Department of Energy evaluated the economic viability of tire pyrolysis and published its findings in a report entitled Scrap Tires A Resource and Technology Evaluation of Tire Pyrolysis and Other Selected Alternative Technologies.2 Their "Economic Results" stated in part ... 

Dodds, J., W.F. Domenico, D.R. Evans, W. Fish, P.L. Lassahnn, and W.J. Toth. SCRAP TIRES A Resource and Technology Evaluation of Tire Pyrolysis and Other Selected Alternate Technologies. U.S Department of Energy. November, 1983. 

He is currently supervising a group of 15 students and scientists in the field of pyrolysis of plastic waste in a fluidized bed process and a group in the field of metal-locene/methylaluminoxane chemistry. His past experience includes the development of pilot plants for the feedstock recycling of plastic wastes and scrap tires, and discovering highly active metallocene catalysts for the polymerization of olefins. He has published more than 300 papers and books and holds 20 patents. He has organized several international symposia in the field of pyrolysis and olefin polymerization. 

H. Sinn and W. Kaminsky Pyrolysis of Plastic Waste and Scrap Tires Using a Fluidized-Bed Process. Abstr. Pap. Am. Chem. Soc., 94 (1979). 

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