Auto shredder residue recycling: Mechanical separation and pyrolysis

Directive 2000/53/EC sets a goal of 85% material recycling from end-of-life vehicles (ELVs) by the end of 2015. The current ELV recycling rate is around 80%, while the remaining waste is called automotive shredder residue (ASR), or car fluff. In Europe, this is mainly landfilled because it is extremely heterogeneous and often polluted with car fluids. Despite technical difficulties, in the coming years it will be necessary to recover materials from car fluff in order to meet the ELV Directive requirement. This study deals with ASR pretreatment and pyrolysis, and aims to determine whether the ELV material recycling target may be achieved by car fluff mechanical separation followed by pyrolysis with a bench scale reactor. Results show that flotation followed by pyrolysis of the light, organic fraction may be a suitable ASR recycling technique if the oil can be further refined and used as a chemical. Moreover, metals are liberated during thermal cracking and can be easily separated from the pyrolysis char, amounting to roughly 5% in mass. Lastly, pyrolysis can be a good starting point from a "waste-to-chemicals" perspective, but further research should be done with a focus on oil and gas refining, in order both to make products suitable for the chemical industry and to render the whole recycling process economically feasible.     

Recovering metallic fractions from waste electrical and electronic equipment by a novel vibration system

The need to recover and recycle valuable resources from Waste Electrical and Electronic Equipment (WEEE) is of growing importance as increasing amounts are generated due to shorter product life cycles, market expansions, new product developments and, higher consumption and production rates. The European Commission (EC) directive, 2002/96/EC, on WEEE became law in UK in January 2007 setting targets to recover up to 80% of all WEEE generated.Printed Wire Board (PWB) and/or Printed Circuit Board (PCB) is an important component of WEEE with an ever increasing tonnage being generated. However, the lack of an accurate estimate for PCB production, future supply and uncertain demands of its recycled materials in international markets has provided the motivation to explore different approaches to recycle PCBs.The work contained in this paper focuses on a novel, dry separation methodology in which vertical vibration is used to separate the metallic and non-metallic fractions of PCBs. When PCBs were comminuted to less than 1 mm in size, metallic grades as high as 95% (measured by heavy liquid analysis) could be achieved in the recovered products.     

废印制线路板真空热解产物分析

在自行设计的间歇式固定床真空热解装置中热解废印制线路板(PCB),对热解产物进行了分析.在热解温度为550 ℃、热解压力为20 kPa、恒温时间为60 min的条件下,得到的热解产物质量分数为:热解渣70%;热解油3%～4%;不可冷凝热解气26%～27%.经气相色谱-质谱联用(GC-MS)分析,热解油经常压蒸馏后得到的低沸点液态油中含有29种化合物,主要有苯酚、对异丙基酚、3-乙基酚、4-甲酚及2-溴苯酚,还含有少量含溴化合物和含氯化合物.热解油经简单的蒸馏就可达到回收酚类化合物的目的.热解渣经风选可实现铜与黏附有碳黑的玻璃纤维的分离,其中铜质量分数约30%,黏附有碳黑的玻璃纤维质量分数约70%.     

Characterization of products obtained from pyrolysis and steam gasification of wood waste,RDF, and RPF

Pyrolysis and steam gasification of woody biomass chip (WBC) obtained from construction and demolition wastes, refuse-derived fuel (RDF), and refuse paper and plastic fuel (RPF) were performed at various temperatures using a lab-scale instrument. The gas, liquid, and solid products were examined to determine their generation amounts, properties, and the carbon balance between raw material and products.The amount of product gas and its hydrogen concentration showed a considerable difference depending on pyrolysis and steam gasification at higher temperature. The reaction of steam and solid product, char, contributed to an increase in gas amount and hydrogen concentration. The amount of liquid products generated greatly depended on temperature rather than pyrolysis or steam gasification. The compositions of liquid product varied relying on raw materials used at 500 °C but the polycyclic aromatic hydrocarbons became the major compounds at 900 °C irrespective of the raw materials used. Almost fixed carbon (FC) of raw materials remained as solid products under pyrolysis condition whereas FC started to decompose at 700 °C under steam gasification condition.For WBC, both char utilization by pyrolysis at low temperature (500 °C) and syngas recovery by steam gasification at higher temperature (900 °C) might be practical options. From the results of carbon balance of RDF and RPF, it was confirmed that the carbon conversion to liquid products conspicuously increased as the amount of plastic increased in the raw material. To recover feedstock from RPF, pyrolysis for oil recovery at low temperature (500 °C) might be one of viable options. Steam gasification at 900 °C could be an option but the method of tar reforming (e.g. catalyst utilization) should be considered.     

Characteristics of products and PCDD/DF emissions from a pyrolysis process of urethane/styrofoam waste from electrical home appliances

A plastic fraction consisting mainly of polyurethane/styrofoam waste is generated after separating valuable spare parts and metals from used electrical home appliances. In Korea, such waste is currently incinerated in cement kilns or is landfilled. However, owing to its high volatile matter content, conversion into gaseous or liquid pyrolysis products is a preferable alternative. A pyrolysis process of polyurethane and styrofoam waste from electrical home appliances was evaluated by characterizing the products generated at 500°–800°C. The para meters determined were the yields of gas, oil, and char; the characteristics of the remaining char; and the con centration of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzo-furans in the product gas. As expected, the char yield decreased at higher temperatures, whereas gas and oil yields showed increasing tendency. The oil products could be used as storable fuels with a calorific value of 6000–8000 kcal/kg. Fine pores were observed in the char. The adsorption and decolorizing ability of the char were almost the same as those of activated carbon, so that pyrolysis char has potential for use as a sorbent. Further feasibility studies will be needed before utilizing pyrolysis technology to recover either fuels or usable products from polyurethane/styrofoam waste.     

Pyrolysis of waste tyres: A review

Approximately 1.5 billion tyres are produced each year which will eventually enter the waste stream representing a major potential waste and environmental problem. However, there is growing interest in pyrolysis as a technology to treat tyres to produce valuable oil, char and gas products. The most common reactors used are fixed-bed (batch), screw kiln, rotary kiln, vacuum and fluidised-bed. The key influence on the product yield, and gas and oil composition, is the type of reactor used which in turn determines the temperature and heating rate. Tyre pyrolysis oil is chemically very complex containing aliphatic, aromatic, hetero-atom and polar fractions. The fuel characteristics of the tyre oil shows that it is similar to a gas oil or light fuel oil and has been successfully combusted in test furnaces and engines. The main gases produced from the pyrolysis of waste tyres are H₂, C₁–C₄ hydrocarbons, CO₂, CO and H₂S. Upgrading tyre pyrolysis products to high value products has concentrated on char upgrading to higher quality carbon black and to activated carbon. The use of catalysts to upgrade the oil to a aromatic-rich chemical feedstock or the production of hydrogen from waste tyres has also been reported. Examples of commercial and semi-commercial scale tyre pyrolysis systems show that small scale batch reactors and continuous rotary kiln reactors have been developed to commercial scale.     

Utilization of magnetic and electrostatic separation in the recycling of printed circuit boards scrap

The progress of the technology is directly related to the growth of production and consumption of electrical/electronics equipment, especially of personal computers. This type of equipment has a relatively short average lifetime, 2-3 years. The amount of defective or obsolete equipment has been increasing substantially; consequently its disposition and/or recycling should be studied. In this work, printed circuit boards, which are used in personal computers, were studied in order to recover the metals in the circuit boards through mechanical processing, such as crushing, screening, as well as magnetic and electrostatic separation. The results obtained demonstrate the feasibility of using these processes to separate metal fractions from polymers and ceramics, and that it is possible to obtain a fraction concentrated in metals containing more than 50% on average of copper, 24% of tin and 8% of lead.     

Pyrolysis and dehalogenation of plastics from waste electrical and electronic equipment (WEEE): A review

Plastics from waste electrical and electronic equipment (WEEE) have been an important environmental problem because these plastics commonly contain toxic halogenated flame retardants which may cause serious environmental pollution, especially the formation of carcinogenic substances polybrominated dibenzo dioxins/furans (PBDD/Fs), during treat process of these plastics. Pyrolysis has been proposed as a viable processing route for recycling the organic compounds in WEEE plastics into fuels and chemical feedstock. However, dehalogenation procedures are also necessary during treat process, because the oils collected in single pyrolysis process may contain numerous halogenated organic compounds, which would detrimentally impact the reuse of these pyrolysis oils. Currently, dehalogenation has become a significant topic in recycling of WEEE plastics by pyrolysis. In order to fulfill the better resource utilization of the WEEE plastics, the compositions, characteristics and dehalogenation methods during the pyrolysis recycling process of WEEE plastics were reviewed in this paper. Dehalogenation and the decomposition or pyrolysis of WEEE plastics can be carried out simultaneously or successively. It could be ‘dehalogenating prior to pyrolysing plastics’, ‘performing dehalogenation and pyrolysis at the same time’ or ‘pyrolysing plastics first then upgrading pyrolysis oils’. The first strategy essentially is the two-stage pyrolysis with the release of halogen hydrides at low pyrolysis temperature region which is separate from the decomposition of polymer matrixes, thus obtaining halogenated free oil products. The second strategy is the most common method. Zeolite or other type of catalyst can be used in the pyrolysis process for removing organohalogens. The third strategy separate pyrolysis and dehalogenation of WEEE plastics, which can, to some degree, avoid the problem of oil value decline due to the use of catalyst, but obviously, this strategy may increase the cost of whole recycling process.     

Conventional and fast pyrolysis of automobile shredder residues (ASR)

This work aims at comparing performance and product yields in conventional pyrolysis and fast pyrolysis of automotive shredded residues. In both processes, carbon conversion to gaseous and liquid products was more than 80%. Gas production was maximised in conventional pyrolysis (about 35% by weight of the initial ASR weight), while fast pyrolysis led to an oil yield higher than 55%. Higher heating values (HHV) of both conventional pyrolysis gas and fast pyrolysis oil increased from 8.8 to 25.07 MJ/Nm3 and from 28.8 and 36.27 MJ/kg with increasing pyrolysis temperature.     

Effect of some environmentally degradable materials on the pyrolysis of plastics II: influence of cellulose and lignin on the pyrolysis of complex mixtures

Pyrolysis of polymer mixtures with a composition similar to that of municipal plastic waste containing polyvinyl chloride (PVC) and of municipal plastic waste free of PVC was performed in the presence of components of biomass, namely lignin, cellulose, or both. The pyrolysis products were characterized by standard methods utilized in the petrochemical industry, i.e., paraffins-isoparaffinsolefins-naphthenes-aromatics analysis, proton nuclear magnetic resonance and infrared spectroscopy, and gas chromatography-mass spectrometry. Up to 3 wt% lignin, cellulose, or both in mixed polymers changed the material balance of pyrolysis by decreasing the amount of waxy products. The presence of both PVC and biomass components significantly changed the material balance by decreasing the waxy product yield and increasing the gas and coke yield. The composition of all pyrolysis products was also modified with the addition of PVC, components of biomass, or both.     

Reaction Kinetic Model For Optimal Pyrolysis Of Plastic Waste Mixtures

Reaction kinetics at various temperatures for pyrolysis of mixtures of plastic waste [polyethylene(PE) and polystyrene(PS)] are modelled in terms of five types of pyrolysis reaction. The model development is based on the assumption that as plastic wastes are heated in a non-reactive environment they are decomposed homogeneously to various products of gas, oil and char by a first-order rate, irreversible reaction and isothermal condition. Among the five models, the type II model in which the activated polymer exists as an intermediate product is the most accurate in predicting the pyrolysis products of pure PE or pure PS. Also, for mixtures of plastics both type II and IV models can be used to explain the composition of pyrolysis products. Furthermore, from the analysis of variance (ANOVA), the mixing ratio and temperature are shown to be the parameters that have the greatest effect on the pyrolysis reaction of polymer waste mixture. The pyrolysis reaction time for the maximum oil production from PE-PS mixtures is shorter than for PE alone and approaches that of PS alone. Oil production increases with increase of PS content. The optimal temperature for maximum oil production is 600°C for the pyrolysis of 2:8, 5:5 and 1:0 mixtures (w/w) of PE and PS. Oil production for PS alone is constant when the pyrolysis is above 600°C.     

Pyrolysis of latex gloves in the presence of Y-zeolite

In this study we have investigated the possibility of processing waste rubber gloves using pyrolysis. Y-zeolite catalyst was employed to upgrade the pyrolysis products to give higher yields of valuable aromatic compounds such as toluene and xylenes. The composition of the pyrolysis products was determined using gas chromatography with linked mass spectrometry (GC-MS), gas chromatograph equipped with a flame ionization detector (GC-FID), gas chromatograph fitted with dual thermal conductivity detectors (GC-TCD), and Fourier Transform Infra-Red Spectrometry (FT-IR). It was found that when rubber gloves were pyrolysed in the absence of a catalyst, the pyrolysis oil consisted mainly of limonene and oligomers of polyisoprene. When Y-zeolite was added to the reaction system, the yields of toluene, xylene, methylbenzenes, ethylbenzenes, and naphthalenes increased dramatically. The Y-zeolite also catalysed the decomposition of limonene, which was absent from the catalytic pyrolysis products. The presence of the Y-zeolite catalyst also increased the yield of hydrocarbon gases. The tests were carried out at both 380 degrees C and 480 degrees C and it was found that the higher reaction temperature led to increased yields of all the major compounds, both in the presence and absence of the Y-zeolite catalyst.     

Pyrolysis of polyethylene mixed with paper and wood: Interaction effects on tar, char and gas yields

In the present study the interactions between the main constituents of the refuse derived fuel (plastics, paper, and wood) during pyrolysis were studied. Binary mixtures of polyethylene-paper and polyethylene/sawdust have been transformed into pellets and pyrolyzed. Various mixtures with different composition were analyzed and pyrolysis products (tar, gas, and char) were collected. The mixtures of wood/PE and paper/PE have a different behavior. The wood/PE mixtures showed a much reduced interaction of the various compounds because the yields of pyrolysis products of the mixture can be predicted as linear combination of those of the pure components. On the contrary, a strong char yield increase was found at a low heating rate for paper/PE mixtures. In order to explain the results, the ability of wood and paper char to adsorb and convert the products of PE pyrolysis into was studied. Adsorption and desorption tests were performed on the char obtained by paper and wood by using n-hexadecane as a model compound for the heavy products of PE pyrolysis.     

TG-DSC and FTIR study on pyrolysis of irradiation cross-linked polyethylene

Irradiation cross-linked polyethylene (PEX) and irradiation cross-linked polyethylene with carbon black filler (CB-PEX) are two types of scraps, generated in electric cable production. Their pyrolysis is studied in this work using instrumental TG\DSC\FTIR techniques and kinetic analysis. The experiments are performed at a constant heating rate of 10 °C/min in nitrogen flow at atmospheric pressure. It is found that the main pyrolysis stage is in the temperature range of 395–503 °C for PEX, and in range of 408–515 °C for CB-PEX. In the main pyrolysis stage, CB-PEX requires more external heat than PEX does. Olefins are the major products of pyrolysis for both materials, but they are quite different in their composition and molecular weight distribution. PEX can be converted almost quantitatively into volatile compounds. CB-PEX has a stronger coking tendency, as well as a larger residue composed of carbon black.     

热解温度对青霉素菌渣热解产物的影响

将青霉素菌渣在400～700℃进行热解,研究了产物中热解炭、热解油及气体的产率,以及热解油的组成变化.实验结果表明:600℃时热解油产率最高,随着温度升高,热解炭的产率降低,气体的产率升高;热解油中含量最高的是含氧化合物,在400℃时质量分数达到最高值69.69％,含氧化合物的含量随着热解温度的升高而降低,酸和醇类是热...     

Characteristics of gas and residues produced from electric arc pyrolysis of waste lubricating oil

An attempted has been made to recover high-calorific fuel gas and useful carbonaceous residue by the electric arc pyrolysis of waste lubricating oil. The characteristics of gas and residues produced from electric arc pyrolysis of waste lubricating oil were investigated in this study. The produced gas was mainly composed of hydrogen (35–40%), acetylene (13–20%), ethylene (3–4%) and other hydrocarbons, whereas the concentration of CO was very low. Calorific values of gas ranged from 11,000 to 13,000 kcal kg^?1 and the concentrations of toxic gases, such as NO_x, HCl and HF, were below the regulatory emissions limit. Gas chromatography–mass spectrometry (GC/MS) analysis of liquid-phase residues showed that high molecular-weight hydrocarbons in waste lubricating oil were pyrolyzed into low molecular-weight hydrocarbons and hydrogen. Dehydrogenation was found to be the main pyrolysis mechanism due to the high reaction temperature induced by electric arc. The average particle size of soot as carbonaceous residue was about 10 μm. The carbon content and heavy metals in soot were above 60% and below 0.01 ppm, respectively. The utilization of soot as industrial material resources such as carbon black seems to be feasible after refining and grinding.     

Pyrolysis of waste animal fats in a fixed-bed reactor: Production and characterization of bio-oil and bio-char

Several animal (lamb, poultry and swine) fatty wastes were pyrolyzed under nitrogen, in a laboratory scale fixed-bed reactor and the main products (liquid bio-oil, solid bio-char and syngas) were obtained. The purpose of this study is to produce and characterize bio-oil and bio-char obtained from pyrolysis of animal fatty wastes. The maximum production of bio-oil was achieved at a pyrolysis temperature of 500 °C and a heating rate of 5 °C/min. The chemical (GC–MS analyses) and spectroscopic analyses (FTIR analyses) of bio-oil showed that it is a complex mixture consisting of different classes of organic compounds, i.e., hydrocarbons (alkanes, alkenes, cyclic compounds…etc.), carboxylic acids, aldehydes, ketones, esters,…etc. According to fuel properties, produced bio-oils showed good properties, suitable for its use as an engine fuel or as a potential source for synthetic fuels and chemical feedstock. Obtained bio-chars had low carbon content and high ash content which make them unattractive for as renewable source energy.     

Valorisation of waste tyre by pyrolysis in a moving bed reactor

The aim of this work is to assess the behaviour of a moving bed reactor, based on a screw transporter design, in waste tyre pyrolysis under several experimental conditions. Waste tyre represents a significant problem in developed countries and it is necessary to develop new technology that could easily process big amounts of this potentially raw material. In this work, the influence of the main pyrolysis process variables (temperature, solid residence time, mass flow rate and inert gas flow) has been studied by a thorough analysis of product yields and properties. It has been found that regardless the process operational parameters, a total waste tyre devolatilisation is achieved, producing a pyrolytic carbon black with a volatile matter content under 5 wt.%. In addition, it has been proven that, in the range studied, the most influencing process variables are temperature and solid mass flow rate, mainly because both variables modify the gas residence time inside the reactor. In addition, it has been found that the modification of these variables affects to the chemical properties of the products. This fact is mainly associated to the different cracking reaction of the primary pyrolysis products.     

Sustainability analysis of organic fraction of municipal solid waste conversion techniques for efficient resource recovery in India through case studies

Worldwide solid waste generation is nearly 1.3 billion tonnes/year, whereas in India 62 million tonnes of solid waste is generated per year by 377 million urban people. The increasing amount of solid waste in India, nearly 50% of which is organic matter, is the major concern for treatment and waste management. Several technologies are already in practice for the treatment of organic fraction of municipal solid waste (OFMSW) in India. It is important to assess the sustainability of these processes. In this study, the existing OFMSW technologies in India were examined. Case-study approach was taken for this purpose along with some published secondary reports. It was found that the selection of technology quite depends on the composition of the OFMSW. Food waste rich fractions are recommended for biomethanation, whereas the fractions rich in market waste and household waste are suitable for composting. Fractions rich in lignin and lignocellulosic materials are suitable for pyrolysis and gasification, whereas the rejects are to be sent for RDF preparation. Based on the findings, a sustainable framework has also been proposed, implementation of which may result in better waste management.     

Recycling of non-metallic fractions from waste electrical and electronic equipment (WEEE): A review

The world’s waste electrical and electronic equipment (WEEE) consumption has increased incredibly in recent decades, which have drawn much attention from the public. However, the major economic driving force for recycling of WEEE is the value of the metallic fractions (MFs). The non-metallic fractions (NMFs), which take up a large proportion of E-wastes, were treated by incineration or landfill in the past. NMFs from WEEE contain heavy metals, brominated flame retardant (BFRs) and other toxic and hazardous substances. Combustion as well as landfill may cause serious environmental problems. Therefore, research on resource reutilization and safe disposal of the NMFs from WEEE has a great significance from the viewpoint of environmental protection. Among the enormous variety of NMFs from WEEE, some of them are quite easy to recycle while others are difficult, such as plastics, glass and NMFs from waste printed circuit boards (WPCBs). In this paper, we mainly focus on the intractable NMFs from WEEE. Methods and technologies of recycling the two types of NMFs from WEEE, plastics, glass are reviewed in this paper. For WEEE plastics, the pyrolysis technology has the lowest energy consumption and the pyrolysis oil could be obtained, but the containing of BFRs makes the pyrolysis recycling process problematic. Supercritical fluids (SCF) and gasification technology have a potentially smaller environmental impact than pyrolysis process, but the energy consumption is higher. With regard to WEEE glass, lead removing is requisite before the reutilization of the cathode ray tube (CRT) funnel glass, and the recycling of liquid crystal display (LCD) glass is economically viable for the containing of precious metals (indium and tin). However, the environmental assessment of the recycling process is essential and important before the industrialized production stage. For example, noise and dust should be evaluated during the glass cutting process. This study could contribute significantly to understanding the recycling methods of NMFs from WEEE and serve as guidance for the future technology research and development.