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Recycling of Scrap Tires to Oil and Carbon Black by Vacuum Pyrolysis
Abstract
Tire recycling has become a necessity because of the huge piles of tires that represent a threat to the environment. There is about one worn tire produced per year and per person in the developed countries. The used tires represent a source of energy and valuable chemical products. By thermal decomposition of rubber under reduced pressure, it is possible to recover the useful compounds. A step-by-step approach has been used, from bench-scale batch systems, to process a development unit and finally a pilot plant, to experiment and develop vacuum pyrolysis of used tires. Yields are 55% oil, 25% carbon black, 9% steel, 5% fiber and 6% gas. The maximum recovery of oil was performed at 415°C below 2 kPa abs. The specific gravity of this oil was 0.95, its gross heating value was 43 MJ/kg and total sulfur content about 0.8%. It was rich in benzol and other petrochemical components. The carbon black favorably compared with the low standard grades and may find an application in lowgrade rubber goods following further research and development. The heat of pyrolysis for the reactions is low, estimated around 700 kJ/kg. The process has been tested in a 200 kg/h pilot plant, which positively demonstrated the possibility of continuously feeding large chunks of rubber under vacuum. The process feasibility is promising, with returns on the investment of 31% after three years of operation.
... m/m sulphur, which is important from the aspect of using char as a fuel, and that its heating value is ranging in the interval 27-29 MJ/kg. Some authors state that the heating value of char is approximately 30 MJ/kg [32,42]. Choi et al. [43] conducted one-and two-stage pyrolysis of tyres waste. ...
... At such parameters the yield of liquid distillates is maximized, while char is reduced to a minimum. Roy et al. [42] performed pyrolysis with a constant temperature of 500 °C, but varied the pressure in the interval 0.8-28 kPa. It was shown that the change in pressure did not significantly affect the yield of pyrolysis as a whole, and that the change in pressure did not affect the change in the yield of any individual product. ...
This paper presents the results of investigations on the pyrolysis of tyres waste in a laboratory fixed bed batch reactor. The results regarding the influence of either the reaction temperature (425, 450, 475, and 500 °C) and the flow of the inert gas (0, 100, 300, and 500 mL/min) on products yield (referred to pyrolysis of waste tyres) are also considered and discussed. On the basis of the above mentioned findings, the most appropriate experimental conditions were selected to contribute to a higher yield of pyrolysis oil. The sample of pyrolysis oil obtained from the experiments carried out in the selected optimal conditions (reaction time 120 min, temperature 450 °C and the inert gas flow of 100 mL/min) was subjected to a calorimetric and infrared spectroscopy analysis. The results of IR spectroscopy analysis on this oil sample showed the following content in percentages (by mass): 32.59 % of aromatics, 51.06 % of paraffins and 16.35 % of naphthenes. The pyrolysis oil so obtained has a high calorific value (42 MJ/kg) and a low sulfur content (0.41 % by mass), which makes it an excellent raw material for energy production. The solid product, i.e. pyrolysis char or carbon black, has the potential to be used as an adsorbent or catalyst support after an activation process, which changes its irregular pore structure to a more voluminous one, making the overall structure more crystalline and symmetrical. Pyrolysis coal has a fairly high calorific value of 31 MJ/kg, when compared to typical solid fuels, so it can be used in energy production or as a feedstock for the gasification process.
... Thermal decomposition or pyrolysis of rubber under reduced pressure has been reported and is being used for the recovery of useful components. 81 It is regarded as a promising disposal method for waste tires. Carbon black and oil are the two main tire pyrolysis products. ...
... Also, recycling whole tires is seemingly more efficient, thus reducing the shredding and ball milling problem. 81 Some of the research also focuses on waste tire 1 The former also reduces the overall environmental impact of tire materials through circular processes and improves the performance characteristics and longevity. As suggested in each subsection earlier, tire companies are developing new technologies for the discussed sustainable materials. ...
The development of a 100% sustainable tire has emerged as a milestone for several tire companies across the globe. It has created new commercial opportunities for the biobased, renewable, and recycled polymer materials. However, there are concerns that the incorporation of such sustainable new materials may have an undesirable impact on the main performance properties of the tire. At the same time, with new capabilities and product innovations, it can help us meet society’s need in a more sustainable fashion and protect the environment. This Feature first outlines the opportunities and need for sustainable tire materials. Next, it describes the main types of sustainable material attributes in tire material, elastomers, reinforcing agents, fibers, and plasticizers, among a few others. The challenges to achieving the performance properties are discussed with possible design guidelines. Recent approaches to the tire attributes are described in the form of a meticulous overview of the existing literature, with a critical analysis of some of them. This contribution attempts to highlight, in a comprehensive way, sustainable tire materials on the basis of recent research advancements, existing challenges, and prospective future scope in this field.
... Tire recycling has become a need that has been identified since the 1980s, mainly due to the existence of huge tires piles accumulated and dispersed all over the world, which represent a serious environmental problem needing a solution. Roy et al. (1990) presents one of the first works where the possibility of recycling scrap tires to oil and carbon black using pyrolysis is possible, since, as the authors refer, scrap tires represent an immense source of energy and chemical products [30]. In other words, as sustained in the work, the thermochemical decomposition of rubber, occurring at low pressure, allows the recovery of various compounds, which can be reused and valued. ...
... Tire recycling has become a need that has been identified since the 1980s, mainly due to the existence of huge tires piles accumulated and dispersed all over the world, which represent a serious environmental problem needing a solution. Roy et al. (1990) presents one of the first works where the possibility of recycling scrap tires to oil and carbon black using pyrolysis is possible, since, as the authors refer, scrap tires represent an immense source of energy and chemical products [30]. In other words, as sustained in the work, the thermochemical decomposition of rubber, occurring at low pressure, allows the recovery of various compounds, which can be reused and valued. ...
The common use of tires is responsible for the production of large quantities of waste worldwide, which are landfilled or energetically recovered, with higher economical cost and known environmentally harmful consequences. This type of problem must be studied, and all efforts must be conducted to eliminate, or at least mitigate, such high costs. The use of thermochemical conversion processes, such as pyrolysis, can allow the recycling and the reuse of raw materials for the tire industry, namely, in the production of carbon black, usually produced using the controlled combustion of fossil fuels. This article reports the production of torrefied and carbonized waste tire samples using a laboratorial procedure, and their subsequent laboratory characterization, specifically the elemental and proximate analysis. This preliminary approach found that carbon concentration in the produced rubber char reached values higher than 75%, indicating the possibility of its reuse in the production of carbon black to in turn be used in the production of new tires or other industrial rubber materials. The possibility of using this rubber char for other uses, such as energy recovery, is still depending on further studies, namely, the evaluation of the amount of sulfur present in the final product.
... Pyrolysis is an alternative for the conversion of tires into energy; it consists of the thermal decomposition of macromolecules in the absence of oxygen to obtain products such as liquids, gases and residual carbon that can be used as raw materials for other processes or as fuels [13], [14], [15]. Coal can be used as a solid fuel or can be converted into activated carbon. ...
Waste tires, composed of rubber, have caused negative environmental problems. There have been problems regarding an increase in the accumulation of tires in different sectors, together with the fact that waste management methods are obsolete. These problems have awakened interest in their study and thermal degradation. Tires composed of rubber represent a material with an important potential for recycling and utilization, together with the conversion of these wastes into energy, value-added products or for the improvement of raw materials. The technique used to carry out thermal degradation is called pyrolysis and consists of heating the organic matter in the absence of oxygen at a specified rate or heating rate, up to a maximum temperature known as pyrolysis temperature, and maintaining it there for a specified time. The products of pyrolysis correspond to: liquid, condensable gases and solid char or ash; for its part, the condensable gas can be further decomposed into non-condensable gases (〖CO, CO2, H2 and CH4), liquid and char. This work aims to contribute with the design and simulation of the condensation cycle of the gases obtained from pyrolysis. Particularly, for the condensation of these gases, the ASPEN HYSYS process simulator was used, where the adaptation of a shell and tube heat exchanger allowed to carry out the condensation. The feed containing these gases comes from tests in a pyrolytic reactor with favorable results. As a result of this condensation and the operating conditions, it is observed that, for a range between 80 and 90 °C, the condensation of gases such as i-Butene and Propylene is favored. This study aims to take up existing research in this area and make a proposal for the condensation of pyrolysis gases, generating an idea of the feasibility and recovery of tire waste with a circular economy approach.
The process of disposing discarded tyre is considered as a significant environmental and economic concern. As a result, many recycling technologies have been investigated to account for their re–use. Pyrolysis is considered to be most hopeful of all these methods. Pyrolysis is the process of a waste tyre being thermally degraded at a high temperature. The value–added products of the pyrolysis process include tyre pyrolysis oil (TPO), pyrochar, and pyrogas etc. TPO corresponds to an alternative fuel for engines as well as a starting material for producing of benzene, toluene, xylene, and limonene. In process of producing carbon nanotubes (CNTs), TPO is used as a precursor. Transformation of porous carbon structure from pyrochar is utilized for absorption and energy storage in batteries and supercapacitors. Pyrogas acts as a source of hydrogen and also may be utilized as an industrial fuel. Pyrolysis may be used to turn the waste tyre into useful materials in this fashion. In this review, we collectively addressed the recent developments of the waste tyre disposal and their by–products.
Scrap tire recycling is a concern for local and national governments because of the associated environmental hazards. As motor vehicle use increases around the globe, fueled by booming demand in the emerging market, more governments are imposing stringent recycling rules for scrap tires. New and emerging technologies have been introduced to solve the recycling problem. Pyrolysis, which involves the decomposition of materials at elevated temperatures under inert conditions, converts scrap tires into gas and liquid fuels and these products can be used by other industries such as chemical, energy and transportation industries. The feasibility of pyrolysis depends on several factors, including the material content of the scrap tire and market value of the products. Current and past market conditions suggest that pyrolysis plants can be run profitably as independent operations. This study evaluated the economic potential of the pyrolysis industry based on evolving market conditions and forecasts the potential market size based on the volume of scrap tires expected to come into the market in the next 20 years. Separate models were used for market predictions for Europe and Turkey. The economic benefits of using scrap tire pyrolysis were discussed, including the potential monetary value of adopting such policies for Turkey.
Waste management is an important indicator for creating sustainable and livable cities, but it remains a challenge for many countries around the world. Millions of rubber tire waste pollute the environment due to improper disposal methods, creating a global environmental crisis. The number of rubber tire waste piles continues to grow, posing greater environmental, safety, and aesthetic issues due to a lack of clear disposal options. This chapter gives a general overview of rubber tire waste recycling and disposal worldwide. A brief history of natural and synthetic rubber and global rubber production and consumption was first discussed. Next, various rubber tire recycling and disposal technologies were elaborated. This is followed by discussing the issues involved in recycling and disposal.
Due to the extensive generation of scrap tires around the world, the application of such waste materials has been considered as an environmentally friendly and cost-effective solution. In geotechnical and geo-environmental engineering, sub-productions derived from scrap tires have been effectively reused to modify the problematic expansive soils. However, no further evaluation has been explored on its performance under freeze-thaw weathering. To fill this gap, this paper presents an attempt to investigate the effect of freeze-thaw cycles on volume change, mechanical behaviour and permeability of expansive soils mixed with scrap tire rubbers. Scrap tire rubber in the form of crumb rubber powder was mixed with natural expansive soils with the percent by weight of 0%, 1%, 3%, 6%, 10%, 15% and 25%. All the laboratory tests were performed on expansive soil-rubber mixtures after 0, 1, 2, 3, 6, 10 and 15 freeze-thaw cycles. The volume change, stress-strain response, unconfined compression strength, resilient modulus, strain at failure as well as permeability coefficient of the expansive soil-rubber mixtures have been discussed. The results show that cyclic freeze-thaw has a significant degradation of mechanical and hydraulic performance of expansive soil-rubber mixtures. Small amount of rubber addition (CR = 1– 3%) will make soil less sensitive to swelling-shrinkage, thereby increasing strength/stiffness and reducing permeability. Besides, independent of freeze-thaw cycles, the relations between resilient modulus and unconfined compression strength can be well expressed by a quadratic function. Increasing freeze-thaw cycles significantly increases the void ratio of parent soil matrix, thus leading to the increase in permeability. Additional research is encouraged to explore an effective method to prevent the freeze-thaw triggered performance deterioration of rubber modified expansive soils in practical projects.
Heavy traffic roads combined with large ranges of temperature lead an extensive attention to improve asphalt's performance and durability. This modification intend to offer enhanced strength and stability at both temperature extremes. Nowadays, the addition of polymers and commercial carbon blacks (CBc) are the most frequent. The scrap tyre-derived carbon black (CBp) investigated in this work, has some similar physico-chemical properties comparing to CBc. On the other hand, environmental and bitumen producers are relying on the road construction industry to develop markets for some waste materials which can be cheaply used as reinforcing agents. These aspects together motivate our interest in studying CBp modified asphalt binders. In this perspective, commercial carbon black (CBc) designated ASTM N550 and pyrolytic carbon black (CBp), a by-product of scrap tyre pyrolysis, were compared as modifiers in two different bitumen grades. Standard tests such as penetrability, softening and Fraass breaking points, were performed on straight and modified binders at different CBp and CBc concentrations. Linear viscoelastic properties were also studied at temperatures ranging from 0°C to 60°C. Comparing to the used commercial carbon black, the CBp revealed a good potential as a reinforcing agent. The study suggested that for warm climates, the addition of pyrolytic carbon black may be useful in increasing the rigidity and the elasticity of binders. It also reduces the rutting potential for heavy road traffic pavement sections. The lower susceptibility to crack propagation is exhibited with 5 to 15% CBp blends.
Onahama Smelting & Refining Co., Ltd., the first joint venture of Japanese copper producing firms, started its plant in April 1965, which was originally designed for a capacity of 5, 000 mtpm of cathode copper.
In December 1968, the addition of NO.2 tankhouse raised the capacity of cathode copper up to 12, 000 mtpm.
In 1973, it was further expanded up to 20, 000 mtpm with the addition of NO.2 reverberatory furnace, a Hazelett casting machine, NO.3 tankhouse, a MgO plant and a gypsum plant. Since the start-up of the plant we have made much effort to control the sulfur oxide emission, recovery rate of sulfur from the smelter being kept over 99.7% at present.
We have achieved constant compliance with sulfur oxide emission standard and ambient air standard.
The surface properties of carbon blacks obtained by vacuum pyrolysis of different used rubbers (CB p) and of commercial carbon blacks were measured by inverse gas chromatography (IGC). The dispersive component of the surface energy (γ ds) and the specific interaction (I sp) of the recovered CB p were lower than γ ds and I sp of the virgin carbon black initially present in the rubber. However, γ ds and I sp of recovered medium surface area carbon black and of virgin low-surface-area carbon black were comparable. During the pyrolysis, carbonaceous deposits are formed on the CB p surface. A correlation between γ ds and I sp and the amount of the carbonaceous deposits, measured by ESCA, was found, suggesting that the formation of these deposits is responsible for the decrease of γ ds and I sp.
Increasing numbers of old tires and waste plastics are creating problems regarding their disposal. Alternatively, there is a continuing search for new sources of hydrocarbons as a result of increasing energy and raw material needs. Old tires and waste plastic can be converted by pyrolysis into almost residue free organic raw materials, to meet this need. Two different procedures exist for dealing with plastic waste. Through Re-use the macro-molecular structure stays intact in contrast to other methods (Pyrolysis, Hydrolysis, Burning) which change the chemical structure to produce raw materials or energy. Re-use processes have a negative influence on the macro-molecular structure which is mainly a chain depolymerization effect. These processes take place in rotary kilns, screw-kilns, melting vessels, or fluidized bed reactors. The problem lies in transferring the heat to solid materials in such a way that the conditions of pyrolysis are evenly distributed to produce the desired product spectrum. Using rotary or other indirectly heated kilns with their varying temperature zone results in an uneven decomposition of the material. However by using a quartz sand or carbon black fluidized bed with its even heat transfer properties, uniform conditions for decomposition can be reached. At the University of Hamburg, a fluidized bed process for the pyrolysis of plastic waste and scrap tires has been developing since 1970. Three stages of up-scaling were used - 0.1 kg/h; 10 kg/h; 100 kg/h. This process is described.
The results of a technical and economic evaluation of scrap tire pyrolysis are presented and some other alternative uses for scrap tires are discussed. A scrap tire, by definition in this report, is one for which there is no economic end use. Information is presented on the scrap tire resource, pyrolysis processes, pyrolysis products (char, oil, and gas), markets for these products, and the economics of tire pyrolysis. A discussion is presented on alternative ideas for using scrap tires as an energy resource.
In early February 1990, vandals set fire to a used tire storage facility near Hagersville, Ontario, Canada, During the fire, the Ontario Ministry of Environment and Energy (MOEE) monitored the site and surrounding impact zone for numerous organic contaminants. Samples of air, soil, vegetation, runoff water, and oily residue were collected and analyzed for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). Air samples produced complex incineration patterns with a large number of isomers detected. Total toxicity equivalents (TEQ) at 1 km downwind of the fire were an order of magnitude higher than those at 3 km downwind. Soil samples collected during the fire did not show elevated PCDD or PCDF concentrations, however, low concentrations were detected in vegetation collected at 100 m and 200 m from the site. PCDD and PCDF concentrations in the foliage decreased with time but were still detectable for at least 200 days after the fire started. As the tires burned, water used to extinguish the fire caused runoff of oil and oily water. Unique patterns of PCDDs and PCDFs were detected in these samples.
Used tyres were thermally decomposed under vacuum in a process development unit. At 510°C and total pressure 2–20 kPa, the process yielded 50 wt% oil, 25 wt% carbon black, 9 wt% steel, 5 wt% fibres and 11 wt% gas. Distillation of the pyrolytic oil yielded ∼20 wt% light naphtha (i.b.p. 160°C), 6.8 wt% heavy naphtha (160–204°C), 30.7 wt% middle distillate (204–350°C) and 42.5 wt% of bottom residue (>350°C). d,l-Limonene was one of the major chemicals in the naphtha fraction, with a concentration of ∼7 wt%. The naphtha also had high contents of aromatics, olefins and iso-alkanes (45, 22 and 15 vol. % respectively). Its relatively high levels of sulfur, nitrogen, olefinic and diolefinic compounds would make it unsuitable as a blending component for gasoline without hydrofining and reforming. However, ∼2 vol. % of the naphtha could be blended with hydrofiner feedstock without significantly affecting the process requirements. Approximately 71.1 and 68 wt% of the pyrolytic and petroleum light naphthas respectively were quantified.
A research program was undertaken to evaluate the overall performance of a vacuum pyrolysis process applied to the treatment of Automobile Shredder Residues (ASR). North American and European ASR samples were tested. Vacuum pyrolysis experiments were carried out in the temperature range of 496–536°C and a total pressure of approx. 1–5 kPa. Pyrolysis product yields averaged 52.5 wt.% solid residue, 27.7 wt.% organic liquids, 13.3 wt.% pyrolytic water and 6.6 wt.% pyrolysis gas. Composition of ASR feedstocks and pyrolysis products has been thoroughly characterized. After pyrolysis, ASR volume and weight were reduced 5×and 1.8×, respectively. It was possible to readily recover 14 wt.% of useful metals remaining in the solid residues; the material left over can be safely landfilled. Pyrolytic gas and oil can be used as heating fuels. The heavy fraction of the oil (>400°C) can be added to road bitumens in order to improve their performance. The total oil also represents a challenging matrix for various purposes. The vacuum pyrolysis technology can be seen as an alternative to landfill and incineration.