Cathode Ray Tube Glass Research Articles

Supply planning for industrial ecology and remanufacturing under uncertainty: a numerical study of leaded-waste recovery from television disposal

The use of waste as a raw material for manufacturing is hampered by the uncertainty associated with the availability of supply. Technological change and obsolescence further complicates the ability of decision makers to consider discarded durable products as a potential source of raw materials. This uncertainty complicates remanufacturing and industrial ecology. A problem since remanufacturing and industrial ecology need to be (and can be) profitable as well as environmentally desirable if they are to be encouraged. To address this problem the modelling of the waste flow of durable goods is considered. The disposal of televisions in the United States is used to illustrate the challenges and requirements for forecasting in an environment with supply uncertainty. This example is timely since the diposal of cathode ray tubes (CRTs) in municipal landfills is being banned and an alternate technology trajectory for televisions exists—the flat panel display and phase-out of analogue broadcasting in the US. This paper estimates the waste stream resulting from three different scenarios of CRT leaded-waste disposal patterns. The reuse of lead-containing CRT glass is found to offer potential. The elimination of this controversial waste stream, as a result of replacement by the adoption of flat panel television technology, is still decades away. The findings in this study indicate the range of the quantity of waste that will require an alternative infrastructure as it is displaced from municipal landfills. This study provides important information for both developing a collection infrastructure and processing alternatives to extract the residual value of the disposed of televisions.

The role of forecasting in sustainability

A lack of understanding of the waste flow of durable goods complicates decision-making efforts that will increase sustainability. To address this problem, the modeling of the waste flow of durable goods is considered. Televisions are used to illustrate the requirements for forecasting and the magnitude of the associated uncertainty of the waste flow for a durable good that is impacted by technological change and/or unpredictability in field life. This example is timely due to disposal laws affecting cathode ray tubes (CRTs) and the emergence of alternate technology trajectories for televisions. The findings suggest that the reuse of lead-bearing CRT glass is worthwhile, even though flat panel TV technology will eliminate this controversial waste stream. The findings also indicate the implications of forecasting durable waste flows for decisions regarding policy, business models, required infrastructure and supply chain management.

Recycling of scrap cathode ray tubes.

It is estimated that approximately 50% of the weight of a computer monitor is composed of cathode ray tube (CRT) glass. Thus, the successful recycling of scrap CRT glass can greatly relieve the disposal problem created by scrap monitors. CRT glass may be considered a hazardous waste due to its high lead concentration. A CRT can be divided into panel (front) glass and funnel (back) glass. Several coatings have been applied to the surface of the CRT panel and funnel glass. These coatings may present an adverse effectto the environment by obstructing the recycling and reuse of the CRT glass. To recycle CRT glass, a series of tests has been conducted to remove the coatings from scrap CRT glass. In this study, the CRT panel and funnel glass obtained from scrap computer monitors was cleaned by wet-scrubbing and ultrasonic cleaning methods. This cleaned CRT glass is intended to be recycled and reused by CRT manufacturers. This study shows that the wet-scrubbing method has a better coating removal performance and no associated pollution problem (i.e., no additional chemical additives). Thus, the wet-scrubbing method is recommended for use as a CRT coating removal method. The results of these tests are presented in this paper.

Towards greener disposal of waste cathode ray tubes via ultrasonically enhanced lead leaching

The disposal of waste cathode ray tubes (CRT) from old televisions and discarded computer monitors is rapidly becoming an issue of growing environmental concern due to the leaching of lead and other toxins by groundwater from landfill sites. Imminent legislation in both the EU and the USA is likely to demand much stricter control on the disposal of such hazardous electronic equipment, with a drive towards lead removal prior to landfill and/or recycling. This paper describes the use of power ultrasound to facilitate the removal of lead from the heavily-leaded CRT glass via an accelerated leaching protocol, with the aim of producing a lead-free product for greener disposal or more ideally for glass recycling purposes. The paper also describes the use of cathodic stripping voltammetry at a boron-doped diamond sensor, as a quick, easy and cost-effective technique for monitoring the rate of lead released from the CRT glass into a mildly acidic leachate.

A Study on the Thermal Properties of Glass for Effective Salvage Process of Flat Cathode-ray Tube

The CRT(Cathode-ray Tube) of salvage is a process of separating the panel and funnel to recycle a cathode-ray tube. In this paper, the thermal properties of glass for CRT were studied to improve its recycling ratio. In the salvage process, several patterns of breakage, as called 'comer pull', were easily generated on the sealing surface of panel or funnel glass due to the residual tensile stress, which had correlations with some parameters of the manufacturing process of CRT and the initial material properties of glass. Finite element analyses and experimental approaches on the flit sealing process were carried out to obtain the major characteristic of glass related to the residual stress. From this study, it was identified that the thermal expansion coefficient of glass had much influence on the residual stress of panel glass after frit sealing process. Therefore, the optimal conditions of thermal properties for CRT glass were proposed to achieve an effective salvage process. By using these optimal conditions, the size of comer pull on the panel and funnel glass was reduced to 10% level compared with the original size, and the recycling ratio of CRT was increased in the salvage process.

Glass Tube Design for CRT (Cathode Ray Tube)

Stress and deformation of cathode ray tubes (CRTs) under atmospheric pressure and implosion protection band tightening were analyzed using a finite element method (FEM). The stress and deformation of the tubes were measured experimentally by using strain gages and three-dimensional position measuring techniques. The experimental results showed close agreements with those of the simulation. The location of the highest tensile stress and the effects of tightening of the implosion protection bands on the stress and deformation of the tube were clarified. Long-term reliability of the tubes were also studied by using these simulation techniques and the strength characteristics of the CRT glass taking account of surface roughness and delayed fracture.

Cathode ray tube recycling

Lead and polybrominated flame retardants are the two hazardous materials that can be found in electronic appliances. Particularly, cathode ray tubes (CRT) contain leaded glasses. In a computer monitor, over 98% of the lead is in the CRT. This material is generally not accepted for reuse as a component; only those from televisions can be reused. However, this currently represents only a very small market. Envirocycle (a US company) has developed a process to recycle all glasses contained in CRTs; this process includes cleaning and sorting glass. The product obtained is used for the manufacture of new CRT glass. Some industries have used pulverized glass from CRTs in smelting processes as slagging material instead of sand or slag. In this paper, some environmental issues related to the recycling of computers and television sets, and CRTs from computers are presented and discussed. Different processes used to recycle CRTs are described along with an economic analysis.

Joint Vitrification of Various Mixed Wastes

Mixed wastes involve radioactive constituents and hazardous components and must be conditioned to be disposed. Joint vitrification of low and intermediate level radioactive wastes (LILW) from nuclear power plants, together with spent catalysts, sorbents, and cathode ray tube (CRT) glass is proposed as a suitable means to condition these wastes. Preliminary experiments on vitrification in crucibles in a laboratory-scale resistive furnace were carried out that demonstrate possibility of 40 wt.% LILW salt loading in a batch. Homogeneous silicate- and borosilicatebased glasses have been obtained and characterized. A phase separation problem at high sulfate and chloride content caused a “yellow phase” to be formed. To prevent this, sulfates and chlorides must be separated from the LILW. The most promising method of mixed waste vitrification is inductive melting in a cold crucible (IMCC) because of its high throughput rate, high achievable temperatures, and long lifetime of the apparatus. Bench-scale tests have been carried out. Preliminary testing of IMCC of spent CRT glass and a combined batch of this glass and LILW salt surrogate was also conducted. LILW salt loading in the batch reached 30 wt.%. The starting melt was formed by heating electrically conductive silicon carbide rods in a high frequency electromagnetic field. The CRT glass melt has low electric conductivity and high viscosity at temperatures of about 1200°C, which does not allow the required IMCC starting melt to be formed. Addition of up to 30 wt.% of surrogate RW salts to the batch increases the electric conductivity and reduces the viscosity of the melt to values that support IMCC. The batch is preferably fed as a calcine.

Author index

This experimental study aimed to design an autoclaved aerated concrete (AAC) with different kind of glass wastes as an alternative fine aggregates for mass housing projects that will meet the requirements in order to help contribute to the industry in saving the environment. Moreover we want to encourage the government to find solutions regarding the disposal to landfills of glassy waste materials and provide new knowledge to the contractors and developers on how to improve the construction industry methods and services by using glassy waste to sustain good product performance and meet recycling goals. Different kinds of glass wastes in the form of sub grain packaging glass cullet, CRT (Cathode Ray Tube) panel glass waste and calsi glass, were used as a sand replacement in AAC production. Large proportion of the post-consumer glass is recycled into the packaging stream again, but some sub grain packaging glass cullet does not meet the strict criteria for packaging glass thus is sent to landfill. CRT is classified as a hazardous glass waste and there are several issues surround CRTs which create barriers to increased recovery of the glass. In countries e.g. Latin America and Asia where still CRT glass is being produced even when shredder, the glass stream is a mixture of panel and funnel glass, making it difficult for reuse in new CRTs. Based on our knowledge also calsi glass as a processed blast furnace slag is not used in packaging production. The viability of current and novel applications of mentioned glasses is examined here. Although aerated concrete was initially envisaged as a good insulation material, there has been renewed interest in its structural characteristics in view of its lighter weight, savings in material and potential for large scale utilization of wastes. Due to this fact we undertake the studies of an influence of different amounts of glass wastes onto properties of aerated concrete in terms of physical (microstructure, density), mechanical (compressive and tensile strengths) and chemical characteristic. Use of milled waste glass in concrete as partial re-placement of sand represents an important step towards development of sustainable (environmentally friendly, energy-efficient and economic concrete-based infrastructure systems.

Left Heart Bypass: A Modified Technique

Abundantly available discarded cathode ray tubes are a serious threat to the environment and loss to resource conservation and therefore requiring immediate recycling efforts. In this study, extensive characterization of all parts of the discarded cathode ray tube was carried out using X-ray diffraction, thermo-gravimetric, X-ray photoelectron spectroscopy, Scanning electron microscope, and Energy Dispersive Spectroscopy. The detailed mass balance and the overall potential (market value calculations) of discarded cathode tubes as an urban source, and the techno-economic calculations were carried to provide guidelines for the development of recycling technology. Recycling techniques of cathode-ray tubes were reviewed, and a concise flow sheet for overall recycling was prepared for evaluation and assessment of recycling potential. The thermal response and dissociation kinetics of the phosphor were investigated, and the activation energy in the temperature range (600–930 °C) for thermal processing of phosphor was determined as 105.4 kJ/ mol. Effective recycling of cathode ray tube phosphor can yield 4.5 g of Y, Eu and, La metal values per 500 kg of discarded units with a market value of 835 INR and an overall market value of 115,870 INR ($1567.34). The different fractions of cathode-ray tube glass were recycled using a combination of the pyrometallurgical and hydrometallurgical processes for metal recovery. Recycling of different fractions of hazardous discarded cathode ray tubes is necessary and is beneficial for a circular economy for recovery of phosphor, copper, glass and coating material, plastics, and steel.

Proceedings of hydrology symposium no. 4; research watersheds

Environmental concerns related to the disposal of various waste materials have escalated to a worrying level. Depending on the local industries, different types of waste are generated in huge quantities every year. Hence, the demand for more sustainable development has further increased the importance of green construction. In recent years, extensive study efforts have been made to recycle wastes for possible use in the production of concrete products. This is because concrete blocks seem to be the most popular option for the incorporation of recycled waste materials due to the lower quality requirements of materials. This paper reviews published research works on the use of various kinds of wastes (i.e. recycled concrete, crushed brick, soda lime glass, cathode ray tube glass, crumb rubber, ceramic and tile waste, etc.) in the production of concrete blocks. The common concrete block properties as well as the value-added properties of concrete blocks with incorporated waste materials are highlighted and discussed in this paper. Several unique characteristics of recycled crumb rubber, plastic waste and crushed brick enhance the fire resistance, toughness, functional and insulation properties of concrete blocks. Also, the quantity of these materials incorporated into concrete blocks can be maximized up to 100% as natural aggregate replacements, while their usage can also be limited to below 30% in certain applications in order to meet the standard requirements of concrete blocks. The compliance of concrete blocks with standard requirements and the value-added properties have demonstrated good potential for incorporating wastes as aggregate in concrete blocks.