Environmental burdens in the management of end-of-life cathode ray tubes

We compared the environmental burdens in the management of end-of life cathode ray tubes (CRTs) within two frameworks according to the different technologies of the production of televisions/monitors. In the first case, CRT recycling is addressed to the recovery of the panel and funnel glass for the manufacturing of new CRT screens. In the second case, where flat screen technology has replaced that of CRT, the recycling is addressed to the recovery of the glass cullet and lead for other applications. The impacts were evaluated according to the problem-oriented methodology of the Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands. Our data confirm that in both cases, the recycling treatment allows benefits to be gained for the environment through the recovery of the secondary raw materials. These benefits are higher for the “CRT technology” framework (1 kg CO₂ saved per CRT) than for the “flat screen technology” (0.9 kg CO₂ saved, per CRT, as the highest possible), mainly due to the high energy consumption for lead separation from the funnel glass. Furthermore, the recovery of yttrium from the fluorescent powders that are a residue of the recycling treatment would further improve the CO₂ credit for both the frameworks considered, which would provide a further saving of about 0.75 kg CO₂ per CRT, net of the energy and raw materials needed for the recovery.Overall, this study confirms that, even with a change in the destination of the recovered materials, the recycling processes provide a benefit for the environment: indeed the higher loads for the environment are balanced by avoiding the primary production of the recovered materials.     

The characterization of waste cathode-ray tube glass

New re-use applications are needed to address the relatively large quantity of waste electronic products generated in the world. Cathode-ray tubes (CRTs) from computer monitors and TV sets are a large component of such waste. The three glass components of CRTs are the funnel, panel and neck, which are produced by various manufacturers and are now collected by asset-recovery centres. In this paper, we characterize waste funnel and panel glass from dismantled cathode-ray tubes with a view to assisting the development of new re-use applications. The heavy metal (lead, barium, and strontium) content of such glass represents an acute risk to the environment. Our results of the chemical composition for different kinds of waste CRT glass including black & white and color CRTs show that CRT glass from different producers have generally similar chemical compositions. In particular, the compositions of funnel and panel black & white CRT glass are similar, but are different to those of panel and funnel color CRT glass. We also measured the following specific properties of each type of CRT glass: density, glass transition temperature, and linear coefficient of thermal expansion. It was found that the coefficients of thermal expansion of CRT glass do not vary with their composition. In contrast, the measured densities and glass transition temperatures do vary with composition. On the basis of our experimental data and data found in the literature, we outline the main properties of several waste CRT glass currently in circulation. The aim of this study was to provide the data required to determine if this kind of waste could be entirely (or partially) re-used and to aid the search for promising methods of treatment.     

Quantification and probabilistic modeling of CRT obsolescence for the State of Delaware

The cessation of production and replacement of cathode ray tube (CRT) displays with flat screen displays have resulted in the proliferation of CRTs in the electronic waste (e-waste) recycle stream. However, due to the nature of the technology and presence of hazardous components such as lead, CRTs are the most challenging of electronic components to recycle. In the State of Delaware it is due to this challenge and the resulting expense combined with the large quantities of CRTs in the recycle stream that electronic recyclers now charge to accept Delaware’s e-waste. Therefore it is imperative that the Delaware Solid Waste Authority (DSWA) understand future quantities of CRTs entering the waste stream. This study presents the results of an assessment of CRT obsolescence in the State of Delaware. A prediction model was created utilizing publicized sales data, a variety of lifespan data as well as historic Delaware CRT collection rates. Both a deterministic and a probabilistic approach using Monte Carlo Simulation (MCS) were performed to forecast rates of CRT obsolescence to be anticipated in the State of Delaware. Results indicate that the peak of CRT obsolescence in Delaware has already passed, although CRTs are anticipated to enter the waste stream likely until 2033.     

Direction of CRT waste glass processing: electronics recycling industry communication

Cathode Ray Tube, CRT, waste glass recycling has plagued glass manufacturers, electronics recyclers and electronics waste policy makers for decades because the total supply of waste glass exceeds demand, and the formulations of CRT glass are ill suited for most reuse options. The solutions are to separate the undesirable components (e.g. lead oxide) in the waste and create demand for new products. Achieving this is no simple feat, however, as there are many obstacles: limited knowledge of waste glass composition; limited automation in the recycling process; transportation of recycled material; and a weak and underdeveloped market. Thus one of the main goals of this paper is to advise electronic glass recyclers on how to best manage a diverse supply of glass waste and successfully market to end users. Further, this paper offers future directions for academic and industry research. To develop the recommendations offered here, a combination of approaches were used: (1) a thorough study of historic trends in CRT glass chemistry; (2) bulk glass collection and analysis of cullet from a large-scale glass recycler; (3) conversations with industry members and a review of potential applications; and (4) evaluation of the economic viability of specific uses for recycled CRT glass. If academia and industry can solve these problems (for example by creating a database of composition organized by manufacturer and glass source) then the reuse of CRT glass can be increased.     

Recycling and pollution control of the End of Life Vehicles in China

The quantity of vehicles has increased rapidly in recent years in China; however, the recycling of End of Life Vehicles (ELV) faces several problems and barriers including the collection difficulty and the environmental pollution caused by improper dismantling. In this paper, based on analysis of the basic situation regarding management and recycling of ELV in China, the ELV flow was introduced, and the potential ELV quantity was estimated. The current management regulations and policies were summarized, and dismantling and pollution control technologies for ELV recycling were introduced, too. It was suggested that with the rapid growth of ELV quantities, more regulations will be enacted, and the recycling network will be more effective; the dismantling technology and pollution control measures will be upgraded, and the recycling and remanufacturing industries will be more combined. The government should pay more attention to improve the management and supervision of, and encourage the development of, high level enterprises.     

Encapsulation of lead from hazardous CRT glass wastes using biopolymer cross-linked concrete systems

Discarded computer monitors and television sets are identified as hazardous materials due to the high content of lead in their cathode ray tubes (CRTs). Over 98% of lead is found in CRT glass. More than 75% of obsolete electronics including TV and CRT monitors are in storage because appropriate e-waste management and remediation technologies are insufficient. Already an e-waste tsunami is starting to roll across the US and the whole world. Thus, a new technology was developed as an alternative to current disposal methods; this method uses a concrete composite crosslinked with minute amounts of biopolymers and a crosslinking agent. Commercially available microbial biopolymers of xanthan gum and guar gum were used to encapsulate CRT wastes, reducing Pb leachability as measured by standard USEPA methods. In this investigation, the synergistic effect of the crosslinking reaction was observed through blending two different biopolymers or adding a crosslinking agent in biopolymer solution. This CRT-biopolymer-concrete (CBC) composite showed higher compressive strength than the standard concrete and a considerable decrease in lead leachability.     

Cathode ray tube glass recycling: an example of clean technology.

In this study the use of 'cleaned' end of life (EOL) cathode ray tube (CRT) glass as a raw material in ceramic glazes is described. At present, the recycling and industrial utilization of CRT, a glass material from TV and computer sets, is a subject of intense research with particular regard to the so-called open-loop recycling, namely cycles different from that of the origin. However, the use of CRT glass as a secondary raw material is strictly related to the demand of high-quality raw material. The good preliminary results reached by introducing clean TV and PC monitor panel and cone glass into ceramic glaze formulations pushed research toward the setting-up of a base glaze that is exploitable for the production of pigmented, silk-screened and flame-hardened glazes (products used industrially for coating floor tiles). The aesthetic and chemical characterization of the tiles glazed by this product showed an extremely similar behaviour to originals that did not contain CRT glass. The good technical results achieved have been supported by the life cycle assessment analysis, which has demonstrated a reduction of the environmental impact of the CRT glass-containing ceramic glaze with respect to the standard one.     

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.     

从废阴极射线管含铅玻璃中回收金属铅的研究进展

随着显像管技术的发展,我国迎来了大量阴极射线管(CRT)玻璃的报废期。废弃的CRT玻璃中含有大量的铅,属于危险废物。从国内外废CRT含铅玻璃的处理处置现状出发,归纳总结了废CRT含铅玻璃中铅的分离回收技术工艺,并分析了其特点及存在的问题。指出,未来该领域新技术的研发应同时注重4个方面:铅的回收率高,对玻璃中的其他组分能够有效利用,满足经济可行性要求,便于工业化生产。     

Recovery of yttrium from cathode ray tubes and lamps’ fluorescent powders: experimental results and economic simulation

In this paper, yttrium recovery from fluorescent powder of lamps and cathode ray tubes (CRTs) is described. The process for treating these materials includes the following: (a) acid leaching, (b) purification of the leach liquors using sodium hydroxide and sodium sulfide, (c) precipitation of yttrium using oxalic acid, and (d) calcinations of oxalates for production of yttrium oxides.Experimental results have shown that process conditions necessary to purify the solutions and recover yttrium strongly depend on composition of the leach liquor, in other words, whether the powder comes from treatment of CRTs or lamp. In the optimal experimental conditions, the recoveries of yttrium oxide are about 95%, 55%, and 65% for CRT, lamps, and CRT/lamp mixture (called MIX) powders, respectively. The lower yields obtained during treatments of MIX and lamp powders are probably due to the co-precipitation of yttrium together with other metals contained in the lamps powder only. Yttrium loss can be reduced to minimum changing the experimental conditions with respect to the case of the CRT process. In any case, the purity of final products from CRT, lamps, and MIX is greater than 95%.Moreover, the possibility to treat simultaneously both CRT and lamp powders is very important and interesting from an industrial point of view since it could be possible to run a single plant treating fluorescent powder coming from two different electronic wastes.     

Composition of plastics from waste electrical and electronic equipment (WEEE) by direct sampling

This paper describes a direct analysis study carried out in a recycling unit for waste electrical and electronic equipment (WEEE) in Portugal to characterize the plastic constituents of WEEE. Approximately 3400 items, including cooling appliances, small WEEE, printers, copying equipment, central processing units, cathode ray tube (CRT) monitors and CRT televisions were characterized, with the analysis finding around 6000 kg of plastics with several polymer types. The most common polymers are polystyrene, acrylonitrile-butadiene-styrene, polycarbonate blends, high-impact polystyrene and polypropylene. Additives to darken color are common contaminants in these plastics when used in CRT televisions and small WEEE. These additives can make plastic identification difficult, along with missing polymer identification and flame retardant identification marks. These drawbacks contribute to the inefficiency of manual dismantling of WEEE, which is the typical recycling process in Portugal. The information found here can be used to set a baseline for the plastics recycling industry and provide information for ecodesign in electrical and electronic equipment production.     

Chemical characterization and toxicity assessment for the sustainable management of end of life cathode ray tubes

Journal of Material Cycles and Waste Management - Cathode ray tube (CRT) monitors represent currently one of the most produced category of electronic waste. In CRTs most of the glass components...     

E-waste assessment methodology and validation in India

An attempt has been made to establish an approach and a methodology to quantify electronic waste (e-waste) in India. The study was limited to personal computers (PCs) and televisions (TVs) within the state boundaries of Delhi and in selected areas in the National Capital Region (NCR). Material flow analysis was used to establish an e-waste trade value chain, where cathode ray tubes (CRTs) were tracked in the e-waste dismantling stream of the CRT regunning process. The market supply method was used to estimate the theoretical amount of e-waste for each item. Sensitivity analysis was carried out for PCs, using 5 years and 7 years as the average life, and for TVs, using 10 years and 12 years as the average life. Externalities such as e-waste entering the study area from outside were factored into the final e-waste analysis. Sensitivity analysis on the average life also factored in elements of active usage, reuse, and storage of electronic items and consumer behavior into assumptions about the obsolescence rate in market supply method. A primary survey indicated an output of 1800–2100 CRTs per day from all regunning units in the study area. This range validated the theoretical output for an average life of 7 years for a PC and 12 years for a TV. Using this approach, e-waste was estimated to reach 2 million units from the domestic market by 2010.     

发达国家废玻璃回收利用经验及借鉴

介绍了发达国家处理和再利用废玻璃的经验,提出我国应借鉴发达国家经验,从科研、政策、法律等方面加强废玻璃的再利用工作。     

我国报废汽车回收拆解企业发展的关键问题研究

报废汽车回收拆解具有巨大的经济、环境和社会效益。我国报废汽车回收拆解企业正面临极佳的发展环境,但目前存在着诸多问题,需要进行转型升级。提出报废汽车回收拆解企业转型升级过程中存在的若干关键问题,即回收阶段中的报废汽车量预测、回收模式选择、报废汽车回收网络构建;拆解阶段中的拆解工艺选择、拆解设备选择;产品销售阶段中的产品分类及市场分析、销售模式确定及销售网络构建、产品定价等问题,并对这些问题进行分析,提供解决方法和措施。     

Forecasting quantities of disused household CRT appliances--a regional case study approach and its application to Baden-Württemberg

Due to special requirements regarding logistics and recycling, disused cathode ray tube (CRT) appliances are handled in some countries as a separate waste fraction. This article presents a forecast of future household waste CRT quantities based on the past and present equipment of households with television sets and computer monitors. Additional aspects taken into consideration are the product life time distribution and the ongoing change in display technology. Although CRT technology is fading out, the findings of this forecast show that quantities of waste CRT appliances will not decrease before 2012 in Baden-Württemberg, Germany. The results of this regional case study are not quantitatively transferable without further analysis. The method provided allows analysts to consider how the time shift between production and discard could impact recycling options, and the method could be valuable for future similar analyses elsewhere.     

Metallurgical use of glass fractions from waste electric and electronic equipment (WEEE)

Within the European Union, it is estimated that between 8 and 9 million tonnes of waste electric and electronic equipment (WEEE) arises annually, of which television sets and computers account for an important part. Traditionally, Cathode Ray Tubes (CRT) have been used for TVs and computer monitors, but are rapidly being replaced by flat-screen technology. Only part of the discarded CRT glass is being recycled. Primary smelters use large amounts of silica flux to form iron-silicate slag, and can, in most cases, tolerate lead input. Use of discarded CRT glass in copper smelting is a potential alternative for utilization of the glass.The mineralogical composition of a slag sampled during ordinary slag praxis has been compared with that of a mixture of slag and CRT glass when re-melted and slowly cooled. Slag (iron-silicate slag) from Boliden Mineral AB, Sweden, was used for the experiments. Slag and glass have been mixed in various proportions: pure slag, pure glass, 90% slag-10% glass and 65% slag-35% glass, and heated in an inert atmosphere up to 1400 °C in a Netzsch Thermal Analysis (TA) instrument. The re-melted material has been analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to determine changes in mineralogical composition after mixing with glass.The results show that the main mineralogical component of the slag is fayalite; the CRT glass is amorphous. The main crystalline phases of the slag do not change with addition of glass. An amorphous phase appears when the addition of glass is increased, which gives the sample a different structure.     

我国废旧电子电器产品拆解技术、设备应用现状及改进建议

从我国废旧电子电器回收行业基本情况、专业技术人才情况、相关企业拆解技术设备情况等方面，阐述了我国废旧电子电器产品拆解技术、设备应用现状，并提出相关改进提升建议。     

Sustainable design for automotive products: Dismantling and recycling of end-of-life vehicles

The growth in automotive production has increased the number of end-of-life vehicles (ELVs) annually. The traditional approach ELV processing involves dismantling, shredding, and landfill disposal. The “3R” (i.e., reduce, reuse, and recycle) principle has been increasingly employed in processing ELVs, particularly ELV parts, to promote sustainable development. The first step in processing ELVs is dismantling. However, certain parts of the vehicle are difficult to disassemble and use in practice. The extended producer responsibility policy requires carmakers to contribute in the processing of scrap cars either for their own developmental needs or for social responsibility. The design for dismantling approach can be an effective solution to the existing difficulties in dismantling ELVs. This approach can also provide guidelines in the design of automotive products. This paper illustrates the difficulty of handling polymers in dashboards. The physical properties of polymers prevent easy separation and recycling by using mechanical methods. Thus, dealers have to rely on chemical methods such as pyrolysis. Therefore, car designers should use a single material to benefit dealers. The use of materials for effective end-of-life processing without sacrificing the original performance requirements of the vehicle should be explored.     

关于我国报废汽车市场发展趋势的初步研究

随着汽车保有量的快速上升,我国报废汽车市场规模正在进入快速增长区间。根据发达国家的经验,报废汽车拆解与回收利用是循环经济产业的重要支柱。未来我国报废汽车市场规模的增长以及相关资源回收利用市场的发展,将会产生许多新的市场机会,也会对我国循环经济产业发展产生较大影响。