Abstract:
The invention relates a pyrolytic carbon black produced from pyrolyzed rubber, the pyrolytic carbon black having an ash content ranging between 9-15%, a toluene discoloration at 425 mu of between 80-90% transmission, an iodine adsorption between 30 and 45 mg/g; and, an n-dibutyl phthalate absorption number of or to 65 cc/100 gm.

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application is a divisional of application Ser. No. 12/697,818 filed Feb. 1, 2010, which is a non-provisional of provisional application No. 61/162,847 filed Mar. 24, 2009. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of waste recycling, and more particularly, to methods for reclaiming useful carbonaceous materials from scrap rubber materials, such as, for example, scrap rubber tires. 
     BACKGROUND OF THE INVENTION 
     The continuing accumulation of scrap tires is a major global environmental hazard. The industrialized world continues to amass used tires at the alarming yearly rate of one for every man, woman, and child. 
     According to the Rubber Association of Canada, there are 29.8 million scrap tires generated annually in Canada (equating to 37.1 million passenger tire equivalents). This generation comes from both the replacement tire market and vehicles that have been scrapped. 
     In the United States, the Rubber Manufacturers Association estimates that 299 million scrap tires were generated in 2005. Of this, an estimated 42 million tires were stockpiled in landfills, contributing to a total 188 million tires in total stockpiled across the US (the US EPA estimates the stockpiled amount to be 265 million). 
     Generally, landfill use is declining while the recycling of tires is growing. Currently, approximately 70% of scrap tires are processed in Canada with the balance being stockpiled or exported. However, these proportions can vary considerably by province. For instance, it is estimated that roughly half of all scrap tires generated in Ontario each year are sent over the US/Canada border to be burned as fuel in the US. In Quebec, somewhere between 30% and 40% of scrap tires each year are sent to privately-owned stockpiles located throughout the province. 
     Moreover, the demanding product specifications for safe, durable tires make scrap tires difficult and expensive to break down. 
     Tires, which are generally composed of approximately 65% rubber, 10% fibre and 12.5% steel by weight, can be recycled in two forms: processed and whole. Whole tire recycling involves using the old tire, as is, for other purposes (e.g., landscape borders, playground structures, dock bumpers and highway crash barriers). The recycling of processed tires, on the other hand, requires first reducing the tire to smaller pieces. This can be accomplished by chopping, shredding, or grinding at ambient or cryogenic temperature. 
     Punching or die cutting small sections of rubber from tire treads or sidewalls can be used to create items such as water troughs. This technique is typically done with non-road tires, such as those used on earth moving or mining equipment, or farm tractors. 
     The process of shredding and grinding scrap tire rubber, and the shred size, depends upon its intended end use. Possible applications include using shred as a lightweight fill for highway embankments, retaining walls and bridge abutments, and as an insulation to limit the depth of frost penetration beneath roads. 
     Crumb rubber is produced by either an ambient or cryogenic grinding process. Ambient processing is conducted at room temperature. Cryogenic processing uses liquid nitrogen, or other materials or methods, to freeze the rubber chips or particles prior to further size reduction. Particle sizes range from one-quarter inch to fine powder generally used for producing molded products. Uses for larger sized crumb rubber include safety and cushioning surfaces for playgrounds, horse arenas and walking and jogging paths. 
     Through the use of heat and pressure and a binder, crumb rubber may be molded into various products. Examples include rubber mats used in skating rinks, roof shakes, and rubber mattresses used in livestock stalls. 
     The production of energy from tires, although technically not a form of recycling, accounts for a significant proportion of used tire disposal. In this application, scrap tires are used as an alternative to coal for fuel in cement kilns, pulp and paper mills, and industrial and utility boilers. This is especially the case in the United States, where tire-derived fuel (TDF) accounted for approximately 155 million scrap tires in 2005, or about 52% of all scrap tires generated. 
     The tire recycling market faces challenges in that recycled rubber products often cannot meet the quality of products made from virgin rubber, yet they often are more expensive to make. For example, rubberized asphalt is more expensive than normal asphalt, but has not proved to be superior to it; in fact, many transportation engineers are skeptical of its merits. When it is time to repave a rubberized-asphalt road, the top layer cannot be stripped off, heated and reused, because the heat burns the rubber and releases toxic emissions. In addition, rubberized asphalt consumes 25% more petroleum. 
     As well, considerable research has gone into rubber devulcanization, whereby recycled tires are used in the production of molded or die cut rubber materials such as mats, tubs, and pails such as mats, tubs, and pails. However, the final renewed material has slightly different chemical properties from virgin rubber, and is more rigid and less flexible. As a result, the recycled material does not meet the stringent requirements of modern tire manufactures, nor can it be used in the manufacture of flexible products such as hoses. As these applications account for 85% of Canada&#39;s rubber market, the potential supply of devulcanized rubber tends to exceed demand. In addition, the cost of processing old tires, particularly modern radial tires with steel belts, into devulcanized rubber exceeds the cost of virgin rubber production. As a result of this quality/cost challenge, many rubber recycling enterprises either cannot sustain themselves on a commercially attractive basis, or, worse, cannot prosper without government assistance. 
     Meanwhile, TDF activity has increased, but this is facing more opposition each year. Firstly due to air quality concerns from the general public and civil society organizations. Burning in cement kilns or incinerators results in high NO x , dioxins, PAH, furans, PCB and heavy metals in particulates (flue dusts). Moreover, the high-tech incinerators needed for such operations are very expensive. To ensure their long-term economic stability, heavily-urbanized regions generating a huge and constant supply of scrap tires are required. A current example of public aversion to TDF is the recent ruling by Ontario Divisional Court to uphold a citizen-led appeal of Lafarge Canada&#39;s plan to burn tires and other materials in a cement kiln in Bath, Ontario. The appeal cited concerns about potential air pollution, water contamination, and human health impacts. 
     Pyrolysis systems refer to the thermal processing of waste in the absence (or near absence) of oxygen. Major component fractions resulting from the pyrolysis of vehicle tires are:
         a) a gas stream containing primarily hydrogen, methane, carbon monoxide, carbon dioxide and various other gases. The gas after cleaning is very similar to natural gas with about the same energy content, but with a higher heat content;   b) a liquid fraction of an oil stream containing simple and complex hydrocarbons similar to No. 6 fuel oil; and,   c) a char consisting of almost pure carbon, plus some inert materials (e.g. steel, zinc oxide) originally present in the scrap tire.       

     A traditional pyrolysis process involves heating tires under substantially anaerobic conditions so that the tire material is not completely converted to gases and ash. The typical automobile tire contains approximately 4 litres of oil, about 230 g of fibre, a kilogram or more of carbon black and about a kilogram each of steel and methane. 
     However, despite prior art efforts to commercialize pyrolysis technology, it has not yet been achieved in an economically viable way. Although many pyrolysis projects have been proposed, patented, or built over the past decade, none have been commercially successful. Many of these processes are not truly continuous, but are, in at least some aspects or steps, limited to batch processing techniques. As such, they suffer from not being sufficiently scalable so as to be commercially viable. Others require excessive energy inputs to produce end products of sufficiently high quality to permit recycling, with the result that they are not economical. In particular, the products of batch-type tire pyrolysis have limited marketability due to the low quality of their end products as compared to virgin materials. For instance, prior art pyrolytic carbon black (CBp) typically contains too many contaminants for use in new tires. Moreover, with batch pyrolysis techniques, the consistency of the end products may vary with each run. As such, the resulting CBp cannot compete in the auto, rubber, and other industry sectors, which require consistent a carbon black product. As a result, much of the CBp arising from existing pyrolysis processes are used as high grade coal for the fuel industry, as well as for industrial hoses, mats, roofing materials and moldings. 
     Accordingly, none of these prior art recycling processes have received the widespread acceptance level necessary to effectively tackle the environmental problem posed by ever-increasing levels of scrap tires. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is disclosed an environmentally friendly, commercially viable, and substantially continuous process for recycling scrap rubber tires to produce distillate oil and gas, steel, and CBp of consistently high quality. Oil recovered from the process has been verified to be within the specifications for No. 6 fuel oil. The type of steel generated by the pyrolysis process of the present invention is classified as a No. 1 or No. 2 Heavy Melting Steel (HMS). The quality of the CBp has been verified to have characteristics comparable to virgin Prime N-600 or N-700 series of carbon black. 
     According to a further aspect of the present invention there is described recycled rubber when produced by a continuous process comprising the steps of:
         a) shredding cleaned rubber tires into shreds less than 2″ long, and preferably 1.5″ long.   b) pyrolyzing the shreds in a reaction chamber of a thermal processor in a first anaerobic environment to produce a char;   c) drawing off volatile organics from the reaction chamber;   d) removing the char from the reaction chamber;   e) cooling the char in a second anaerobic environment;   f) removing metal and textile components from the char to obtain CBp;   g) milling and sizing the CBp so obtained into particles of 325 mesh size or smaller; and,   h) utilizing the CBp from the previous step in a polymerization process that produces said recycled rubber.       

     According to another aspect of the present invention, the temperature within the reaction chamber is between about 450-550° C., and preferably at about 500° C. More specifically, a temperature profile exists, where the temperature is maintained in four zones for at least 30 minutes each. Preferably, the temperature profile is in 4 different zones: 500, 550, 550, 550° C. for at least 30 minutes. 
     According to yet another aspect of the present invention, the recycled rubber process further comprises, after step g), and before step h), the step of pelletizing the CBp into pellets of 60 to 100 mesh size. 
     According to yet another aspect of the present invention, the recycled rubber product of the above process has a minimum tensile strength ranging between 2500-3100 psi. 
     According to another aspect of the invention, there is produced a high quality CBp from a continuous recycling process for rubber tires comprising the steps of:
         a) shredding cleaned rubber tires into shreds less than 2″ long;   b) pyrolyzing the shreds in a reaction chamber of a thermal processor in a first anaerobic environment to produce a char;   c) drawing off volatile organics from the reaction chamber;   d) removing the char from the reaction chamber;   e) cooling the char in a second anaerobic environment;   f) removing metal and textile components from the char to obtain CBp; and,   g) milling and sizing the CBp so obtained into particles of 325 mesh size or less.       

     According to another aspect of the invention, the process includes, prior to step b), a cleaning sub-process to remove any extraneous and residual materials. 
     According to another aspect of the invention, the process of the previous paragraph further comprises, after step g), the step of pelletizing the CBp into pellets of 60 to 100 mesh size. 
     According to one further aspect of the invention, there is produced, from pyrolyzed rubber, CBp having:
         a) an ash content ranging between 9-15%;   b) a toluene discoloration (425 mu) of 80-90% transmission;   c) an iodine adsorption between 30 and 45 mg/gm; and,   d) an n-dibutyl phthalate absorption number of up to 65 cc/100 gm.       

     According to another aspect of the invention, there is provided a method of reclaiming carbonaceous materials from scrap tires comprising the steps of:
         a) shredding rubber tires into shreds less than 2″ long;   b) pyrolyzing the shreds in a reaction chamber of a thermal processor in a first anaerobic environment to produce a char;   c) drawing off volatile organics from the reaction chamber;   d) removing the char from the reaction chamber;   e) cooling the char in a second anaerobic environment;   f) removing metal and textile components from the char to obtain pyrolytic carbon black;   g) milling and sizing the pyrolytic carbon black so obtained into particles of 325 mesh size or smaller; and,   h) utilizing the pyrolytic carbon black from the previous step in a polymerization process that produces recycled rubber.       

     The process according to the invention is a continuous feed, closed loop, controlled atmosphere pyrolysis process. The process uses special valves to maintain a constant production environment and to be able to consistently produce specified end-use products, including a consistently structured, high quality CBp that the market requires. The process is capable of running 24/7 non-stop for 340 days per year, creating substantially the same end products in characteristic and size throughout the operating term. 
     It is thus an object of this invention to obviate or mitigate at least one of the above mentioned disadvantages of the prior art, and to provide at least one or more of the above-described advantages over the prior art. 
     Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements and structures, and the combination of steps and economies of process, will become more apparent upon consideration of the following detailed description and the appended claims, with reference to the accompanying drawings, the latter of which is briefly described hereinbelow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features which are believed to be characteristic of the process and end products according to the present invention, as to their structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred process according to the invention will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention. In the accompanying drawings: 
         FIGS. 1-4  are different sections of a flow diagram which sections together illustrate an example of a process according to the invention; and 
         FIG. 5  is a detailed diagram of two vertically stacked flap valves referenced in  FIG. 1 . 
         FIGS. 6A-6D  are different sections of a flow diagram showing cleaning steps prior to the process of  FIG. 1 . 
         FIG. 7A  illustrates a representative calciner for use in the process of  FIG. 1 . 
         FIG. 7B  is a detail view of Detail A shown in  FIG. 7A   
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Described herein is a continuous recycling process involving the pyrolytic decomposition of used rubber tires to consistently produce high quality distillate gas, oil, steel, and CBp as end products that have value and use in today&#39;s market. Pyrolysis is meant and understood in this specification and the appended claims to mean the thermal decomposition of matter in the absence (or near absence) of oxygen. In particular, the disclosed process reproducibly yields a pyrolytic carbon black (CBp) that is fine, free of extraneous material, and is of consistently high quality. This high quality CBp can be used in various applications such as molded and extruded rubber, foams, sponge, wire coverings, cable, roofing material etc. It is also possible that certain tire applications such as innerliners, carcasses and side walls could utilize CBp produced by the process of the present invention in a blend with virgin carbon black. 
     The Pre-Treatment of Tires 
     As a prelude to  FIG. 1  and prior to shredding, the tires to be recycled are thoroughly cleaned to remove all extraneous material adhered to the tires such as grit, earth, clay and dirt. It has been found that the removal of all extraneous material is important to ensure the reproducibility and quality of the CBp produced. Residual grit not only adds to the ash content in the carbon black product, but it also raises the energy and cost of the process due to the more arduous milling necessary to grind the grit to the desired particle size. 
     The water used for washing the tires is preferably recycled. Surprisingly, it has been found that this water, which now contains the grit and dirt removed from the tires, becomes increasingly acidic with each wash cycle. This is problematic, as it causes corrosion and pitting of the metallic surfaces of the equipment, such as the blades of the shredder. Therefore, to continuously reuse the water, but eliminate the costly corrosion problems induced by the acidity of the waste water, it must not only be filtered to remove the solid contaminants but must also be neutralized before reintroducing it into the washing cycle. 
     The cleaned tires are shredded in the presence of water not only to provide an additional cleaning step but also to reduce the wear and tear on the blades. The tires are cut into rubber pieces of 2″ (on the diagonal) or less, and preferably 1.5″ or less, and more preferably approximately 1.5″. A selection screen in the shredder (not shown) allows shreds of 1.5″ or smaller to pass through while those that are bigger are returned to the shredder for further shredding. The shreds that pass through the screen are distributed onto a conventional conveyor belt where they are dried by forced, dry and heated air to remove all moisture. Once dried, the shreds are stored in a storage silo. 
     Referring now to  FIGS. 6A-6D , there is shown a preferred embodiment of the cleaning steps that are used to provide some of the aforementioned advantages. First, whole tires are received and weight at scale  210  before being deposited by dump truck  214  onto conveyor  216 . The whole tires are then distributed through diverter  218 , where some tires are placed in outdoor storage for future use, and those to be used are diverted to a primary feed conveyor  220  and onto a primary shredder  222 . Primary shredder  222  shreds the whole tires into relatively larger pieces. Typically, spray water is added to the primary shredder  222  for lubricating the shreds. 
     Next, the shredded tire pieces proceed to a vibratory discharger  224  where sprinklers  226  spray the shreds to wash off dirt and grit. The wash water is collected, and pumped via pump  228  to primary sedimentation tank  230 , with overflow draining to a secondary sedimentation tank  232 , also used as a neutralization tank for pH balancing. It has been discovered that the aforementioned lubricating and wash water becomes acidic, and thus the recycled water is pH balanced prior to being reused. Some of the water is cycled to a storage location as will be described below. 
     Returning now to the path of the tire shreds, and referring to  FIG. 6C , the tire shreds are fed into a secondary shredder  234  where they are preferably shredded into pieces 1.5″ long on the diagonal. These smaller shreds then pass through a double deck disc classifier  236 , that sorts the shreds and directs those sized 1.5″ or smaller to chip storage  238 . The larger sized shreds proceed to a vibrating screen  240  where, any shreds sized 1.5″ or smaller that were not sorted properly by disc classifier  236  are directed to storage  238  and larger sized shreds continue to third shredder  242 . The shreds are then cycled back to the vibratory screen  240 , as shown, and the process is repeated from this point to ensure chip size consistency and provide a maximum number of operational days. Optionally, a dust collection control system may also be installed to control the dust in the surrounding areas and pollution levels, as may be required. The shreds are also preferably dried to have a moisture level of less than 1%. 
       FIG. 6D  shows chip storage  238 , where chips are stored in a number of compartments. Preferably, each compartment includes sprinkler systems  244  using water recycled after pH balancing as discussed above. 
     The shreds are then moved, for example, by front loading vehicles  246  to hopper  248 , from where they are directed to the continuous and complete process according to the invention as described below. 
     The Process 
     Referring now to  FIG. 1 through 4  of the drawings, there is disclosed a continuous and complete process according to the invention for the recycling of used rubber tires shreds. 
     From the storage silo, the rubber shreds are fed into a conveying and dispersing assembly that, for example, could consist of a vibrating feeder  2 , a belt conveyor  4  with belt scale  5 , a hopper  6 , and screw feeder  3 . The purpose of the conveying and dispersing assembly is to transport, on a continuous basis, a measured volume of shreds onto one of two serially arranged, fast acting pneumatic flap valves  7 ,  7 ′ (see  FIG. 5  for more detail) set up in sequence above the opening of the reaction chamber  8   c  of a rotary thermal processor, or calciner  8 . A suitable type of rotary calciner  8  is a gas-fired Bartlett-Snow 72″ diameter Rotary Calciner (shown in  FIG. 7A ) available from Alstom Power, Inc. of Warrenville, Ill., USA. Suitable flap valves  7 ,  7 ′ are available from Alstom Power, Inc. of Warrenville, Ill., USA. The shreds are gravity fed from the screw feeder  3  onto the flap  7   a  of the top flap valve  7  which opens and closes according to a predetermined frequency that is electronically controlled (preferably, about 6 dumps/min). As the flap  7   a  opens, the collection of tire shreds fall by gravity onto the closed flap  7   b  of the bottom flap valve  7 ′, and the top valve  7  immediately returns to its closed position. Thereafter, as the flap  7   b  of the second valve  7 ′ opens, the shreds are fed through a feed chute  1  down into the opening of the rotary calciner  8 . 
     The fast acting pneumatic flap valves  7 ,  7 ′ function as atmospheric interlocks between the open air (oxygenated) environment of the screw feeder  3  and the inert atmosphere (oxygen-free) reaction chamber  8   c  of the calciner  8 . To restrict the unwanted introduction of oxygen into the calciner  8 , an inert gas such as nitrogen is introduced between the two flap valves  7 ,  7 ′ so as to create a positive nitrogen pressure in both valve cavities. Nitrogen is beneficial for two purposes: (i) to create an inert atmosphere to avoid combustion and possible explosion; (ii) the right amount of nitrogen, based on test results is ideally no less than 0.007 volume/minute of the calciner internal volume. Insufficient amounts of nitrogen will affect the char quality. The purpose of the nitrogen is to ensure the calciner is in an inert atmosphere and reduce the chance of pyrolysed gases which could break down and form carbon and redeposit onto the char. Furthermore, it is preferred that the calciner  8  is kept at ¾″ to 1¼″ of negative water column, controlled by a fan at the downstream side, so as to reduce the retention of the pyrolysed gases which could break down and redeposit onto the char. When flaps  7   a ,  7   b  are opened in the aforesaid serial sequence, the positive nitrogen pressure gradient prevents atmospheric oxygen from entering the calciner  8 , as the nitrogen gas forces its way out from flap valves  7 ,  7 ′ to the lower pressure ambient atmosphere. To further reduce the possibility of oxygen entering into the calciner  8 , the opening and closing of flaps  7   a ,  7   b  are electronically controlled (rather than gravity controlled) to ensure efficient and timely closing of at least one of the flaps  7   a ,  7   b  at all times. 
     The thermal processor (i.e. rotary calciner)  8  in which the pyrolysis takes place, is comprised of, inter alia, an internal rotary cylinder having a feed end  8   a  and a discharge end  8   b , with the reaction chamber  8   c  disposed in-between. A spiral flight is preferably located on the internal diameter of the feed end  8   a  of the calciner  8  as well as being present throughout the reaction chamber  8   c . Thus, as the calciner  8  rotates about its longitudinal axis, the spiral flight smoothes out the rubber shreds dumped by the valves  7 ,  7 ′, and propels the shreds forward into the heating zone of the reaction chamber  8   c . The second flight in the reaction chamber  8   c  moves the solid material along the length of the calciner  8  to the discharge end  8   b.    
     To further assist in transporting the solid material forward, the calciner  8  is preferably positioned slightly off the horizontal such that the feed end  8   a  is slightly higher than the discharge end  8   b . This angled position makes use of gravity to further assist in propelling the solid material through the calciner  8 . 
     The rotary calciner  8  is heated indirectly to preferably create four heating zones within the reaction chamber  8   c , each with accessible temperatures ranging between about 450-650° C. A temperature profile is generated according to the type of end products required. Preferably, the heating zones 1, 2, 3 and 4 are heated to 500° C., 550° C., 550° C. and 550° C. respectively. Preferably, the profile has a maximum pyrolysis temperature in the range of about 450-550° C., and preferably about 500° C. in not less than 30 minutes. 
     The pyrolysis reaction taking place inside the calciner  8  is sensitive to oxygen. Both safety (i.e., explosion risk) and quality issues arise if oxygen is allowed to penetrate in any significant amount into the reaction chamber  8   c . Prior to commencing the continuous recycling operation, the calciner  8  must therefore be filled with nitrogen gas (or other inert gas). In addition to also having positive nitrogen pressure in flap valves  7 ,  7 ′, air tight seals  9  must be fitted at the interfaces between the rotating reaction chamber  8   c  and the stationary framework  8   d  surrounding the rotting cylinder to prevent atmospheric oxygen from seeping into the calciner  8  through these interfaces. Gas-tight bellows type seals are preferably used for this purpose. These seals are designed to retain the positive nitrogen pressure within the reaction chamber  8   c  of the calciner  8 . A suitable form of bellows seals is disclosed in U.S. Pat. No. 3,462,160, issued Aug. 19, 1969 to O. J. Adams. 
     In the course of the pyrolysis process, the rubber shreds are heated to temperatures above 450° C., and preferably to about 500 to 550° C. The anaerobic decomposition of the rubber thus caused produces volatile organics which fill the reaction chamber  8   c  as volatile organic gas. The pressure inside the calciner  8  is therefore preferably kept slightly under atmospheric pressure to prevent over pressurization of the reaction chamber  8   c . The pyrolysis gas is extracted at the discharge end  8   b  of the calciner  8  through a discharge pipe  11  on the other side of which is a pressure lower than that in the calciner  8 . The gas in the reaction chamber  8   c  is thus suctioned out through the discharge pipe  11  due to this pressure difference. 
     It has been discovered that in order to produce char of sufficient quality in the pyrolysis process, it is preferable to ensure that the char produced has no, or insignificant amounts of volatile content. Figure The breeching section, that is the end section, of the calciner  8  is maintained at temperature of no less than 500° C. to avoid gaseous condensation back onto the char prior to discharge to the cooler.  FIG. 7   b  shows the discharge end of the representative calciner of  FIG. 7   a . The end section preferably has a continuous sleeve  700  and the area is insulated with insulation  720  and heat traced in order to keep the temperature to at least 500° C. Also shown are a representative bellows seal assembly  740  and cylinder dish end  760 . It will be understood by those skilled in the art that the calciner of FIGS.  7   a  and  7   b  is shown for representative purposes only and is not to be considered limiting on the present invention. Generally, any gaseous re-condensation (i.e. below 500° C.) onto the char will produce char with higher than acceptable volatile content. 
     The pyrolysis gas thus obtained is directed by discharge pipe  11  to an oil quench tower  10  to condense out the heavier gases as oil, and to extract the lighter gas which is drawn from the top end  10   a  of the oil quench tower  10  through suction line  13 , and thence pushed by gas blower  12  through line  17  into a separator  14  (see  FIG. 2 ). The separator  14  functions as another extraction stage to separate the lighter gas fraction from any residual heavier gas that can be condensed to oil and subsequently stored. The lighter gas fraction is drawn from the top  14   a  of the separator  14  through line  25  to storage tank  16 . The lighter gas fraction can be drawn out of storage tank  16  through supply line  27  by blower  18  to a tank truck, train or sip, or to another holding vessel for further use. This gas may also be scrubbed and recycled as fuel for, for example, the burners (not shown) used to heat the rotary calciner  8 . 
     As an aside, test results have indicated that the all oils obtained from the process are characterized as No. 6 oils and accordingly, are not being separated into light and heavy oils. The oils are preferably combined and stored, and two condensers in series are used to condense and collect the oil which is stored in a holding tank and then pumped through a filter prior to the storage tank for shipment. Preferably, a hot cyclone is incorporated prior to the gas condensation phase in order to knock out particulates to prevent plugging of pipes and other elements in the condensation system. The non-condensable gas then goes through a scrubbing process, wherein a caustic solution is used to strip all the acidic components. The scrubbed gas is stored to run the calciner and dryer which is used to dry the CBp pellets. 
     Returning to the process itself, the oil fraction condensed in the lower end  14   b  of the separator  14  exits through line  29  which, in turn, outputs into line  35 . Line  35 , in turn, delivers the oil into storage tank  26   a , or is discharged into line  37 , which optionally directs the oil into storage tank  26   b . Lines  29 ,  35 , and  37  are all fitted with conventional control valves  31  to selectively control the flow of oil through interconnected lines  29 ,  35  and  37 . 
     The oil condensed in the oil quench tower  10  is collected at the lower end  10   b  of the tower  10 , exiting therefrom, through control valve  19 , into supply line  39 , which in turn, ends in a T-junction at bi-directional junction line  43  having oppositely directed branches  43   a  and  43   b . Each branch  43   a  and  43   b , is preferably fitted with a respective control valve  19   a  and  19   b , one on either side of the T-junction with supply line  39 . Moving downstream, each branch  43   a ,  43   b  feeds a respective oil filter  20   a ,  20   b . The oil travels downstream from each of the oil filters  20   a ,  20   b  into respective supply lines  20   c , and  20   d , which are further controlled by control valves  21   a  and  21   b  installed on supply lines  20   c  and  20   d , respectively. Supply lines  20   c  and  20   d  join up downstream of the control valves  21   a  and  21   b  at a T-junction with line  35 . The oil entering line  35  is directed thereafter through a water-cooled oil cooler plate and frame  22  which cools the oil prior to being stored in storage tanks  26   a  or  26   b . The water in the cooler plate and frame  22  circulates through pipe loop  45  fitted with circulation pump  23 . The pipe loop  45  passes through the central cooling water system  24  which cools the warmed water exiting the cooler plate and frame  22  and pumps cold water back into the pipe loop  45 . 
     The oil collected in storage tanks  26   a  and  26   b  can be released from the tanks into line  47 . Through the use of conventional control valves  28 , the oil can either be directed to flow from storage tanks  26   a ,  26   b  into line  49  and thence pumped by pump  30   a  into tank trucks, trains, or ships, or, can be flowed into line  15  and thence pumped by pump  30   b  back to the oil quench tower  10  for further fractionation. 
     Referring again to  FIG. 1 , the hot solid products produced during pyrolysis, i.e. the char, are discharged from the calciner  8  by gravity, falling through the open space of the discharge breeching (not shown) and landing on the first of another two fast acting pneumatic flap valves  53 ,  53 ′ at bottom of the breeching. Flap valves  53 ,  53 ′ are substantially identical to the double flap valves  7 ,  7 ′ positioned at the feed end  8   a  of the rotary calciner  8 , and are also fitted with a gas inlet between them to create a positive nitrogen pressure inside the flap valves  53 ,  53 ′. The use of nitrogen at this stage is important, not only to prevent oxygen from entering into the rotary calciner  8 , but also to prevent oxidation of the hot char. Oxidation of the char would, inter alia, reduce the quality of the CBp end product. The hot char is therefore passed through the double flap valves  53 ,  53 ′ and deposited into the feed end  32   a  of a nitrogen-filled rotary cooler  32 , preferably having flighting on the internal diameter to transport the char through rotary cooler  32  to the discharge end  32   b . A suitable rotary cooler  32  is a Bartlett-Snow 36″ diameter Rotary Cooler available from Alstom Power, Inc. of Warrenville, Ill., USA. The temperature in the rotary cooler  32  is preferably kept low by indirectly cooling the outside surface of the rotating cylinder with water that is continuously circulated by circulation pump  33  through pipe loop  51  and cooled by central cooling water system  24 . 
     The char exits the discharge end  32   b  of the rotary cooler  32  at a sufficiently low temperature, preferably approximately 200° C., that it can thence be exposed to air without significant reaction therewith (i.e., oxidation). Surprisingly, it has been found that the char is not particularly agglomerated at this stage and a de-agglomeration step is not required as previously described in the prior art (see, for example U.S. Pat. No. 5,037,628, issued to John Fader on Aug. 6, 1991). This can be explained by a reduced oil content in the char produced under the stringent anaerobic operating conditions described by the inventor herein and by a pyrolysis temperature of between about 450-550° C., and preferably at about 500° C. The char is preferably discharged from the rotary cooler  32  into an enclosed screw conveyor  55  and then passed through two magnetic separators  34  and  36 : the first to remove the steel  38  from the char, and the second, usually more powerful than the first, to remove rare earth metals and other magnetic matter left behind by the first magnetic separator  34 . The char is transported between the first  34  and second  36  magnetic separators by an enclosed conveyor belt  57 . The steel  38  extracted from the char is preferably transported away to a central collection location by respective conveyors  61   a  and  61   b , whereat, using the natural gas produced from the pyrolysis process, the steel  38  (compacted into) may be heated, compacted and melted into 100 lb briquettes, ready for use in producing new metal products, or for further processing. 
     The char, now free of steel  38  and other magnetic components, is preferably transported by an enclosed conveyor belt  63  from the second magnetic separator  36  to a vibrating screen  40 , (see  FIG. 3 ), preferably of mesh size 100, to separate out any remaining textile fibers or cords  41  that remain as components of the original scrap tire pieces. These textile remnants are removed from the vibrating screen  40  via conveyor belt  65  for subsequent disposal or possible recycling. 
     Solid material fine enough to pass through the vibrating screen  40  and onto conveyor  67  is thence referred to as the ‘crude’ CBp. The conveyor  67  transports the crude CBp to a conventional rotary valve  42  which releases the CBp powder onto an enclosed conveyor  44 . A suitable enclosed conveyor can be, for example, a tip track elevator marketed by Unitrack Corp. of 299 Ward Street, Port Hope, Ontario, Canada. The CBp powder is transported by enclosed conveyor  44  to a vibrating bin discharger  46  fitted with a bin vent filter and top mount fan  48  for pollution control. A speed-controlled electronic feeder  50  releases the crude CBp from the vibrating bin discharger  46  into a mill feed bin  52  via enclosed chute  69 . The crude CBp exits the mill feed bin  52  by gravity, through enclosed chute  81 , into a closed hopper  54 , and thence onto an enclosed conveyor belt  56 , where it is released down chute  72  into a pulverizer  58  to reduce the particle size. Pulverizer  58  is preferably a Palla™ Vibrating Mill. Air borne particulate matter produced in closed hopper  54  is drawn through conduit  73  to a mechanical air classifier  60  fitted with a 325 mesh, and connected to bag filter  62  via conduit  75 . Air borne particles measuring 44 μm or less exit the mechanical air classifier  60  into conduit  77  and are transported therethrough to surge bin  64 , which surge bin  64  is fitted with a level indicator  66 , and with a vent filter and top mount fan  68 . 
     The CBp in the pulverizer  58  is pushed out by blower  59  connected to the pulverizer  58  by conduit  79 . The fine CBp is thus blown out of the pulverizer  58  into the enclosed conveyor  83  which delivers it to the mechanical air classifier  60 . Again, particles of 325 mesh size, or smaller, are directed to surge bin  64  through conduit  77 . Using a closed conveying system  70 , the fine CBp is transported from the surge bin  64  to surge bin  72  (see  FIG. 4 ), also fitted with a level indicator  74  and bin vent filter with a top mount fan  76 . The CBp exits the surge bin  72  through an electronically speed-controlled feeder  78  which delivers a predetermined amount of the powder onto an enclosed conveyor  80  fitted with an impact flow meter  82  to restrict the flow to 3000 lbs/hour. A pin-mixer agglomerator  84  receives the fine CBp where it is pelletized by mixing with a binder solution (supplied from tank  86 ), and/or water. Preferably, the pelletization is achieved with water, and with a binder solution. An air line  88  is connected to the agglomerator  84 , the air being controlled by shut off valve  90  and regulator  92 . 
     The binder solution tank  86 , which holds up to 8000 gallons, is fitted with an agitator  94 , a water pipe  96  controlled by valve  98  and fitted with a 5 micron strainer  100 . A level indicator  102  is also present at the top of the tank  86  to prevent overflow. The flow of the binding solution from the tank  86  through pipe  103  is controlled by a circulation pump  104 . Control valves  106   a  and  106   b , depending on whether opened or closed, can direct the flow of the solution either back into the tank  86 , or into the agglomerator  84 . Water can be introduced directly into the pin-mixer agglomerator  84  through the water line  108 , also fitted with a 5 micron strainer  110 , and controlled by shut off valve  112  and control valve  114 . 
     The CBp exits the agglomerator  84  as pellets, preferably of 60 to 100 mesh size, that are transported by an enclosed conveyor belt  116  to a dryer  118 , ideally fuelled by the gas produced and collected from the pyrolysis process. The pellets, dried to less than 1% humidity, preferably with an indirect rotary dryer, exit the dryer  118  and fall by gravity down an enclosed chute  119  to enclosed conveyor  120  which brings the pellets to a 100 mesh screen separator  122 . Any undersized pellets (i.e., those &lt;149 μm) may passed through a conventional rotary valve  124  and a blower  126  pushes the pellets through conduit  127 , which directs same back to surge bin  72  to be re-agglomerated. The oversize pellets, (i.e. those ≧149 μm), are transported by enclosed conveyor  129  to a vibrating bin  128 , fitted with a butterfly valve  130 , and are ready to be bagged. Any overflow is collected in surge bin  132  fitted with a bin vent filter  134  and level indicator  136 . A rotary valve  138  allows the pellets to exit the surge bin  132  onto enclosed conveyor  140 , ready for bagging. 
     Carbon Black (CBp)—Characteristics and Definitions 
     CBp is not the same as normal cure furnace N series virgin carbon black. Tire composition analysis indicates that there is a fair amount of inorganic compounds, most of these compounds remain with the char after pyrolysis, thus it is possible that the ash content of CBp could be as high as 15% in weight where as virgin carbon black typically has an ash content of below 1%. Small amount of surface deposits of pyrolytic carbon could also be formed and adsorbed on the CBp. However, the amount of insulation on the calciner, the amount of nitrogen and maintaining the calciner system pressure can serve to limit this carbon deposition. 
     It is not unusual to have N100, N200, N300 N600 and N700 series of virgin carbon black in a tire. Thus the recovered CBp will have a mixture of carbon blacks. However, the modified characteristics of the CBp can also be a plus for some specific applications in the plastic and rubber industries. 
     Carbon black is the predominant reinforcing filler used in rubber compounds, and the improvement in rubber properties is a function of the physical and chemical characteristics of carbon black. The most important fundamental physical and chemical properties are aggregate size and shape (structure), particle size, surface activities, and porosity. These properties are distributional in nature and this distribution in properties has an impact on rubber performance. Other non-fundamental properties include the physical form and residue. The physical form of carbon black (beads/pellets or powder) can affect the handling and mixing characteristics of carbon black and hence, rubber properties. The ultimate degree of dispersion is also a function of the mixing procedures and equipment used. 
     Structure/Aggregate Size: Carbon blacks do not exist as primary particles. Primary particles fuse to from aggregates, which may contain large number of particles. The shape and degree of branching of the aggregates is referred to as structure. The structure level of a carbon black ultimately determines its effects on several important in rubber properties. Increasing carbon black structure increases modules, hardness, electrical conductivity, and improves dispersibility of carbon black, but increases compound viscosity. 
     Particle Size is the fundamental property that has a significant effect on rubber properties. Finer particles lead to increased reinforcement, increased abrasion resistance, and improved tensile strength. However, to disperse finer particles requires increased mixing time and energy. Typical particle sizes range around 8 nanometers to 100 nanometers for furnace black. Surface area is used in the industry as an indicator of the fineness level of the carbon black. 
     Surface Activity, or Surface Chemistry is a function of the manufacturing process and the heat history of a carbon black. It is difficult to measure directly, surface activity manifests itself through its effect on rubber properties such as abrasion resistance, tensile strength, hysteresis, and modulus. The effect of surface activity on cure characteristics will depend strongly on the cure system in use. 
     Porosity is a fundamental property of carbon black that can be controlled during the production process. It can affect the measurement of surface area providing a total surface area larger than the external value. Increasing the porosity reduces the density of the aggregates. This allows a rubber compounder to increase carbon loading while maintaining compound specific gravity. This leads to an increase in compound modulus and electrical conductivity for a fixed loading. 
     Physical Form of carbon black has an impact on the handling and mixing characteristics of the carbon black. The most common form of rubber carbon black is beads (pellets). 
     The Pyrolytic Carbon Black (CBp) Product 
     Using their disclosed recycling process, the inventors have demonstrated that the pyrolysis of used rubber tires can generate a CBp that meets the consistently high quality levels demanded by the market. This implies that the CBp produced by the invention has a consistent composition falling within well defined limits following the ASTM (American Society for Testing and Materials) standards testing. To this end, the inventors have carried out extensive research to identify the operating conditions that would result in a CBp that demonstrates acceptable reinforcing levels when used as a filler in rubber. Their findings have shown that the morphology and characteristic of the CBp can be controlled in part by varying the process temperature and residence time. Utilizing the process herein disclosed which allows for strict control of temperature and other parameters such as pressure and the inertness of the gases within the reaction chamber and the cooler, CBp production can be optimized by consistently striking a balance between oil and gas production, and the associated sulphur content in the CBp. 
     These aspects of the invention will be more fully understood by reference to the following examples which are to be considered as merely illustrative thereof. 
     Example 1 
     Cleaned rubber tire shreds of 2″ (on the diagonal) were pyrolyzed in an anaerobic environment at four different temperatures: 450° C., 500° C., 600° C. and 700° C. Table 1 shows the process mass balance at the various pyrolysis temperatures. It can been seen that pyrolysis carried out at the higher temperatures favour oil production and while the lower operating temperatures favour char production. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Temp 
                 Temp 
                 Composition % Wt 
                   
               
             
          
           
               
                   
                 (° C.) 
                 (° F.) 
                 Gases 
                 Oil 
                 Char 
                 Total 
               
               
                   
                   
               
             
          
           
               
                   
                 450 
                 842 
                 5.8 
                 40.2 
                 46.2 
                 92.2 
               
               
                   
                 500 
                 932 
                 3.1 
                 42.3 
                 43.7 
                 89.1 
               
               
                   
                 600 
                 1112 
                 6.2 
                 44.3 
                 40.5 
                 91 
               
               
                   
                 700 
                 1292 
                 5.7 
                 45.5 
                 38.6 
                 89.8 
               
               
                   
                   
               
             
          
         
       
     
     Table 2 shows the gross calorific value and sulphur content of the oil and char generated at the four experimental pyrolysis temperatures. The results indicate that the oil sulphur content is greater at the higher pyrolysis temperatures and that contrarily, the char&#39;s sulphur content increases as the pyrolysis temperature is lowered. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                   
                   
                 Corrected 
                 Corrected 
                   
               
               
                 Temp 
                 Temp 
                 GCV MJ/KG 
                 CV MJ/KG 
                 Sulphur Content % 
               
             
          
           
               
                 (° C.) 
                 (° F.) 
                 Oil 
                 Char 
                 Oil 
                 Char 
               
               
                   
               
             
          
           
               
                 450 
                 842 
                 42.3 +/− 0.3 
                 31.1 +/− 0.6 
                 1.11 +/− 0.09 
                 2.17 +/− 0.13 
               
               
                 500 
                 932 
                 42.4 +/− 0.3 
                 30.2 +/− 0.2 
                 1.11 +/− 0.19 
                 2.21 +/− 0.35 
               
               
                 600 
                 1112 
                 41.9 +/− 0.4 
                 30.7 +/− 0.3 
                 1.27 +/− 0.19 
                 2.04 +/− 0.01 
               
               
                 700 
                 1292 
                 41.2 +/− 0.4 
                 30.6 +/− 0.3 
                 1.27 +/− 0.11 
                 2.10 +/− 0.03 
               
               
                   
               
             
          
         
       
     
     It was also of interest to analyze the surface area of the char as a function of temperature. Table 3 presents the Brunaer, Emmett, and Teller (BET) surface area of the char at the four temperatures investigated. As can be seen, the data suggests that the surface area of the char increases with increasing pyrolysis temperature. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Temp (° C.) 
                 Temp (° F.) 
                 BET (m 2 /g) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 450 
                 842 
                 38 
               
               
                 500 
                 932 
                 55.5 
               
               
                 600 
                 1112 
                 65.7 
               
               
                 700 
                 1292 
                 62.4 
               
               
                   
               
             
          
         
       
     
     The thermal decomposition of rubber in anaerobic conditions generates gaseous products and the rates of emission of these gases were also found to be correlated to the pyrolysis temperature. Tables 4-7 show the evolution rate of hydrogen, carbon monoxide, carbon dioxide, methane and other hydrocarbon (HC) gases at pyrolysis temperatures of 450° C., 500° C., 600° C. and 700° C. respectively. Table 4 shows that at 450° C., gas evolution climbs up and peaks at about 110 minutes into the pyrolysis process and levels off at around 125 minutes. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Time 
                   
                   
                   
                   
                   
                 Other HC 
               
               
                 Cumulative 
                 Temp. 
                 H 2 (g)   
                 CO (g)   
                 CO 2 (g)   
                 CH 4 (g)   
                 Gases 
               
             
          
           
               
                 (min) 
                 (° C.) 
                 Output (Mol) 
               
               
                   
               
             
          
           
               
                 20 
                 110 
                 0.001 
                 0.001 
                 0 
                 0 
                 0.001 
               
               
                 25 
                 200 
                 0.002 
                 0.002 
                 0.001 
                 0 
                 0.006 
               
               
                 35 
                 300 
                 0.003 
                 0.003 
                 0.01 
                   
                 0.013 
               
               
                 40 
                 320 
                 0.004 
                 0.002 
                 0.012 
                 0.007 
                 0.014 
               
               
                 45 
                 325 
                 0.005 
                   
                 0.005 
                 0.012 
                 0.022 
               
               
                 55 
                 400 
                 0.01 
                 0.001 
                 0.003 
                 0.017 
                 0.034 
               
               
                 65 
                 430 
                 0.011 
                 0 
                 0.003 
                 0.02 
                 0.032 
               
               
                 85 
                 450 
                 0.015 
                 0 
                 0.004 
                 0.015 
                 0.02 
               
               
                 105 
                 425 
                 0.065 
                 0.002 
                 0.006 
                 0.036 
                 0.05 
               
               
                 125 
                 405 
                 0.003 
                 0 
                 0 
                 0.002 
                 0.002 
               
               
                 155 
                 400 
                 0.001 
                 0 
                 0 
               
               
                   
               
             
          
         
       
     
     At 500° C., the rate of gas evolution increases significantly and peaks in almost half the time when compared to 450° C., that is around 50 minutes into the pyrolysis process. Gas emission is found to level off around 100 minutes (Table 5). 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Time 
                   
                   
                   
                   
                   
                 Other HC 
               
               
                 Cumulative 
                 Temp. 
                 H 2 (g)   
                 CO (g)   
                 CO 2 (g)   
                 CH 4 (g)   
                 Gases 
               
             
          
           
               
                 (min) 
                 (° C.) 
                 Output (Mol) 
               
               
                   
               
             
          
           
               
                 20 
                 250 
                   
                   
                 0.002 
                 0 
                   
               
               
                 25 
                 360 
                 0.005 
                 0.004 
                   
                 0.006 
                 0.008 
               
               
                 35 
                 400 
                 0.006 
                 0.006 
                 0.007 
                 0.011 
                 0.022 
               
               
                 40 
                 430 
                 0.007 
                 0.004 
                 0.005 
                 0.016 
                 0.03 
               
               
                 45 
                 440 
                 0.01 
                 0.002 
                 0.004 
                 0.018 
                 0.031 
               
               
                 50 
                 460 
                 0.012 
                 0.001 
                   
                 0.014 
                 0.018 
               
               
                 60 
                 480 
                 0.013 
                 0 
                 0.002 
                 0.015 
                 0.02 
               
               
                 70 
                 490 
                 0.011 
                 0.002 
                   
                 0.015 
                 0.012 
               
               
                 100 
                 490 
                 0.01 
                 0.001 
                 0.001 
                 0.006 
                 0.007 
               
               
                 130 
                 500 
                 0.008 
                 0 
                 0 
                 0.003 
                 0.005 
               
               
                 160 
                 500 
                 0.005 
                 0 
                 0 
                 0.002 
                 0.002 
               
               
                   
               
             
          
         
       
     
     As the pyrolysis temperature is increased to 600° C., Table 6 shows that gas evolution peaks earlier, at 40 minutes, and levels off at around 140 minutes. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Time 
                   
                   
                   
                   
                   
                 Other HC 
               
               
                 Cumulative 
                 Temp. 
                 H 2 (g)   
                 CO (g)   
                 CO 2 (g)   
                 CH 4 (g)   
                 Gases 
               
             
          
           
               
                 (min) 
                 (° C.) 
                 Output (Mol) 
               
               
                   
               
             
          
           
               
                 20 
                 250 
                 0.001 
                   
                 0.002 
                 0 
                 0.001 
               
               
                 25 
                 330 
                 0.01 
                 0.001 
                 0.007 
                 0.015 
                 0.023 
               
               
                 35 
                 370 
                 0.015 
                 0.007 
                 0.006 
                 0.011 
                 0.028 
               
               
                 40 
                 410 
                 0.025 
                 0.007 
                 0.001 
                 0.022 
                 0.048 
               
               
                 45 
                 465 
                 0.024 
                 0.004 
                 0.004 
                 0.025 
                 0.072 
               
               
                 50 
                 460 
                 0.022 
                 0.004 
                 0.005 
                 0.025 
                 0.062 
               
               
                 60 
                 500 
                 0.032 
                 0.003 
                 0.002 
                 0.023 
                 0.045 
               
               
                 80 
                 550 
                 0.03 
                 0.002 
                 0.002 
                 0.022 
                 0.022 
               
               
                 110 
                 560 
                 0.02 
                 0.001 
                 0.002 
                 0.01 
                 0.002 
               
               
                 140 
                 565 
                 0.008 
                 0.001 
                 0.001 
                 0.003 
                 0.001 
               
               
                 170 
                 570 
                 0.002 
                 0 
                 0 
                 0 
               
               
                   
               
             
          
         
       
     
     Lastly, Table 7 presents data collected for evolution of the gases when pyrolyzing the rubber shreds at 700° C. It can be seen that gas production peaks at about 38 minutes and levels off around 140 minutes. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Time 
                   
                   
                   
                   
                   
                 Other HC 
               
               
                 Cumulative 
                 Temp. 
                 H 2 (g)   
                 CO (g)   
                 CO 2 (g)   
                 CH 4 (g)   
                 Gases 
               
             
          
           
               
                 (min) 
                 (° C.) 
                 Output (Mol) 
               
               
                   
               
             
          
           
               
                 20 
                 275 
                 0.002 
                   
                   
                 0.002 
                 0.001 
               
               
                 25 
                 410 
                 0.0011 
                 0.005 
                 0.003 
                 0.018 
                 0.028 
               
               
                 35 
                 500 
                 0.047 
                 0.003 
                   
                 0.021 
                 0.093 
               
               
                 40 
                 515 
                 0.04 
                 0.002 
                 0.005 
                   
                 0.054 
               
               
                 45 
                 525 
                 0.054 
                 0.002 
                 0.002 
                 0.043 
                 0.055 
               
               
                 55 
                 590 
                 0.043 
                 0.001 
                 0.002 
                 0.038 
                 0.033 
               
               
                 70 
                 620 
                 0.022 
                 0.003 
                 0.003 
                 0.032 
                 0.022 
               
               
                 85 
                 660 
                 0.028 
                 0.003 
                 0.002 
                 0.015 
                 0.013 
               
               
                 115 
                 650 
                 0.01 
                 0.005 
                 0.005 
                 0.01 
                 0.002 
               
               
                 145 
                 670 
                 0.002 
                 0.002 
                 0.001 
                 0 
                 0 
               
               
                 155 
                 685 
                 0.002 
                 0.001 
                 0 
                 0 
               
               
                   
               
             
          
         
       
     
     In summary, the research shows the critical importance of understanding how the pyrolysis temperature affects the quantity and quality of the oil, char and gas produced. The findings can be summarized as follows:
         For the complete pyrolysis of tires, the operating temperature should not go below about 450° C.   High pyrolysis temperatures favour oil yield and consequently, a lower yield of CBp.   Lower pyrolysis temperatures favour char production and consequently, a lower yield of oil.   The rate of gas evolution increases with increasing pyrolysis temperature.   The CBp product contains a higher sulphur content when produced at lower pyrolysis temperatures.   The oil has a higher sulphur content at higher pyrolysis temperatures.   Higher pyrolysis temperatures favour the formation of a CBp having a greater surface area.       

     Example 2 
     Used rubber tire shreds of 1½ or less were pyrolyzed at 450° C. in an inert nitrogen atmosphere. Following a cooling period, the char was collected and the steel removed with the use of a magnet. The crude CBp was milled to pass a 325-mesh sieve. The milled CBp (bulk density of 25 lb/ft 3 ) was mixed with 1% Norlig G (calcium lignosulphonate binder) then pelletized using an agglomerator. The product was subsequently dried at a temperature of 120° C. and the product screened at 2.0×150 microns (10×100 mesh). The bulk density of the pellets produced was approximately 35 lb/ft 3 . 
     Example 2a 
     The pelletized CBp was subsequently tested in two natural rubber formulations (ASTM D3192). Rubber compound A was formulated with conventional N-762 and rubber compound B with the CBp. The results are presented in Tables 8, 9 and 10. 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 8 
               
               
                   
                   
               
               
                   
                 Compund A 
                 Compound B 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Natural Rubber 
                 100 
                 100 
               
               
                   
                 N-762 
                 50 
                 0 
               
               
                   
                 CBp 
                 0 
                 50 
               
               
                   
                 Zinc Oxide 
                 5 
                 5 
               
               
                   
                 Stearic Acid 
                 3 
                 3 
               
               
                   
                 Sulphur 
                 2.5 
                 2.5 
               
               
                   
                 TBBS 
                 0.6 
                 0.6 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Reometer Cure Data at 145° C. 
               
             
          
           
               
                   
                 Compound A 
                 Compound B 
               
               
                   
                   
               
             
          
           
               
                   
                 Min. Torque, 
                 14.25 
                 11.25 
               
               
                   
                 lb-in 
               
               
                   
                 Max. Torque, 
                 75.5 
                 53.5 
               
               
                   
                 lb-in 
               
               
                   
                 Time to 2-pt 
                 7.5 
                 3.65 
               
               
                   
                 rise, min 
               
               
                   
                 Time to 90% 
                 21.25 
                 14.5 
               
               
                   
                 cure, min 
               
               
                   
                 Cure rate 
                 13.75 
                 10.85 
               
               
                   
                 (t 90  − t 2 ), min 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 Vulcanize Normal Properties 
               
             
          
           
               
                   
                 Compound A 
                 Compound B 
               
               
                   
                   
               
             
          
           
               
                   
                 Cure Time at 145° C., 
                 20 
                 14 
               
               
                   
                 min 
               
               
                   
                 Hardness Shore A 
                 59 
                 53 
               
               
                   
                 Modulus psi 100% 
                 370 
                 225 
               
               
                   
                 Modulus psi, 300% 
                 1770 
                 615 
               
               
                   
                 Tensile Strength psi 
                 3410 
                 2250 
               
               
                   
                 Elongation @ Break % 
                 485 
                 570 
               
               
                   
                 Tear Strength Die C 
                 314 
                 220 
               
               
                   
                 Compression Set % 
                 16.5 
                 19 
               
               
                   
                   
               
             
          
         
       
     
     Example 2b 
     The utility and reliability of the styrene butadiene rubber (SBR) have made this copolymer the most important and widely used rubber in the world. The following results show the reinforcement character of the CBp in a blend formula with a higher structure carbon black, N339. The same blend with conventional N-762 is also compared (Tables 11-13). 
     
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 11 
               
               
                   
                   
               
               
                   
                 Compound A 
                 Compound B 
                 Compound C 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 SBR-1712 
                 137.5 
                 137.5 
                 137.5 
               
               
                   
                 N-339 
                 82.5 
                 41.5 
                 41.5 
               
               
                   
                 N-762 
                 0 
                 0 
                 41.5 
               
               
                   
                 CBp 
                 0 
                 41.5 
                 0 
               
               
                   
                 Sundex 790 
                 25 
                 25 
                 25 
               
               
                   
                 Zinc Oxide 
                 3 
                 3 
                 3 
               
               
                   
                 Sulphur 
                 1.75 
                 1.75 
                 1.75 
               
               
                   
                 Stearic Acid 
                 1.5 
                 1.5 
                 1.5 
               
               
                   
                 TBBS 
                 1.25 
                 1.25 
                 1.25 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 12 
               
             
             
               
                   
               
               
                 Reometer Cure Data at 145° C. 
               
             
          
           
               
                   
                 Compound A 
                 Compound B 
                 Compound C 
               
               
                   
                   
               
             
          
           
               
                 Min. Torque, 
                 14 
                 14 
                 14 
               
               
                 lb-in 
               
               
                 Max. Torque, 
                 41 
                 36 
                 36 
               
               
                 lb-in 
               
               
                 Time to 2-pt 
                 2.7 
                 3.1 
                 3.1 
               
               
                 rise, min 
               
               
                 Time to 90% 
                 6.2 
                 6.9 
                 6.2 
               
               
                 cure, min 
               
               
                 Cure rate 
                 96 
                 80 
                 83 
               
               
                 (t 90  − t 2 ), min 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 13 
               
             
             
               
                   
               
               
                 Vulcanize Normal Properties 
               
             
          
           
               
                   
                 Compound A 
                 Compound B 
                 Compound C 
               
               
                   
                   
               
             
          
           
               
                 Durometer Hardness 
                 65 
                 58 
                 58 
               
               
                 Modulus psi 100% 
                 318 
                 198 
                 253 
               
               
                 Modulus psi, 300% 
                 1258 
                 640 
                 893 
               
               
                 Tensile Strength psi 
                 1986 
                 1139 
                 1430 
               
               
                 Elongation @ Break % 
                 465 
                 547 
                 500 
               
               
                 Specific Gravity 
                 1.15 
                 1.15 
                 1.15 
               
               
                   
               
             
          
         
       
     
     Example 3 
     Used rubber tire shreds of 1½″ or less were pyrolyzed at 500° C. in an inert nitrogen atmosphere. Following a cooling period, the char was collected and the steel removed with the use of a magnet. The crude CBp was milled to pass a 325-mesh sieve. The milled CBp (bulk density of 25 lb/ft 3 ) was mixed with 1% Norlig G (calcium lignosulphonate binder) then pelletized using an agglomerator. The product was subsequently dried at a temperature of 120° C. and the product screened at 2.0×150 microns (10×100 mesh). The bulk density of the pellets produced was approximately 35 lb/ft 3 . 
     Example 3a 
     The CBp was tested by using it in a natural rubber formulation according to ASTM 3192. The results are set out in Tables 14-16. 
     
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 14 
               
               
                   
                   
               
               
                   
                 Compound A 
                 Compound B 
                 Compound C 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Natural 
                 100 
                 100 
                 100 
               
               
                   
                 Rubber 
               
               
                   
                 CBp 
                 50 
                 0 
                 35 
               
               
                   
                 N-762 
                 0 
                 50 
                 0 
               
               
                   
                 N-330 
                 0 
                 0 
                 15 
               
               
                   
                 Zinc Oxide 
                 5 
                 5 
                 5 
               
               
                   
                 Stearic Acid 
                 3 
                 3 
                 3 
               
               
                   
                 Sulphur 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 TBBS 
                 0.6 
                 0.6 
                 0.6 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 15 
               
             
             
               
                   
               
               
                 Reometer Cure Data at 145° C. 
               
             
          
           
               
                   
                 Compound A 
                 Compound B 
                 Compound C 
               
               
                   
                   
               
             
          
           
               
                 Min. Torque, 
                 16.5 
                 16.75 
                 19.25 
               
               
                 lb-in 
               
               
                 Max. Torque, 
                 80.7 
                 81.5 
                 81.5 
               
               
                 lb-in 
               
               
                 Time to 2-pt 
                 3.5 
                 4.5 
                 4 
               
               
                 rise, min 
               
               
                 Time to 90% 
                 18 
                 17 
                 17 
               
               
                 cure, min 
               
               
                 Cure rate 
                 14.5 
                 12.5 
                 13 
               
               
                 (t 90  − t 2 ), min 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 16 
               
             
             
               
                   
               
               
                 Vulcanize Normal Properties 
               
             
          
           
               
                   
                 Compound A 
                 Compound B 
                 Compound C 
               
               
                   
                   
               
             
          
           
               
                 Hardness Shore A 
                 60 
                 61 
                 63 
               
               
                 Modulus psi 100% 
                 345 
                 355 
                 415 
               
               
                 Modulus psi, 300% 
                 1390 
                 1570 
                 1695 
               
               
                 Tensile Strength psi 
                 3640 
                 3280 
                 3645 
               
               
                 Elongation @ Break % 
                 530 
                 490 
                 505 
               
               
                 Tear Strength Die C 
                 357 
                 347 
                 395 
               
               
                   
               
             
          
         
       
     
     Based on the described pyrolysis conditions and follow up controlled operating conditions as described in Examples 1, 2 and 3, the inventors have discovered that the pyrolysis of rubber tire shreds at temperatures between about 450 and 500° C., but preferably at about 500° C., can generate a high grade marketable CBp product. Properties of the CBp produced include a toluene discoloration transmission of 90%. Other characteristic of the CBp are summarized in Table 17 and were measured on a sample free of steel and milled with undersize below 325 mesh prior to pelletization. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 17 
               
               
                   
               
               
                 Properties 
                 UNITS 
                 N762 
                 N550 
                 CBp 
                 ASTM 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Ash content 
                 % 
                 0.26 
                 0.34 
                  9-15 
                 D1516 
               
               
                 Pour density 
                 lb/ft 3   
                 31.2 
                 22.6 
                 24-26 
                 D1513 
               
               
                 Heat loss, as packaged 
                 % 
                 0.1 
                 0.1 
                 1.0 max 
                 D1509 
               
               
                 35 mesh sieve residue 
                 % 
                 0 
                 0 
                 0 
                 D1514 
               
               
                 325 mesh sieve residue 
                 % 
                 0.003 
                 0.002 
                 0.2 max 
                 D1514 
               
               
                 Toluene discoloration, 
                 % 
                 83 
                 95 
                 90 
                 D1613 
               
               
                 425 mu 
               
               
                 Pellet crush strength, 
                 gm 
                 14 
                 8 
                 20 
                 D1937 
               
               
                 min 
               
               
                 Pellet crush strength, 
                 gm 
                 41 
                 32 
                 50 
                 D1937 
               
               
                 max 
               
               
                 Fine 5′ rotap (pelleted 
                 % 
                 4.4 
                 3.6 
                 8 
                 D1508 
               
               
                 fines content) max 
               
               
                 Iodine adsorption 
                 mg/gm 
                 28.3 
                 43.3 
                 30 
                 D1510 
               
               
                 DBP 1   
                 cc/100 gm 
                 64.4 
                 119.9 
                 65 
                 D2414 
               
               
                 Min. tensile-SBR 2   
                 psi 
                 3110 
                 2070 
                 2500 
                 D3191 
               
               
                 Min. tensile-NR 3   
                 psi 
                 3627 
                 3740 
                 3100 
                 D3192 
               
               
                   
               
               
                   1 n-dibutyl phthalate absorption number 
               
               
                   2 styrene-butadiene rubber 
               
               
                   3 natural rubber 
               
             
          
         
       
     
     Other modifications and alterations may be used in the design and manufacture of other embodiments according to the present invention without departing from the spirit and scope of the invention, which is limited only by the accompanying claims.