Recent developments on recycling end-of-life flat panel displays: A comprehensive review focused on indium
ENEA1
04 Mar 2021-Critical Reviews in Environmental Science and Technology (Taylor & Francis)-Vol. 51, Iss: 5, pp 429-456
TL;DR: In this paper, a review of the most recent technologies for indium recovery from waste flat panel displays is provided, which is different from the other fractions obtained after primary dismantling (such as indium fractionation).
Abstract: In this paper, a review of the most recent technologies for indium recovery from waste flat panel displays is provided. Differently from the other fractions obtained after primary dismantling (such...
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TL;DR: The present approach addresses the transdisciplinary problem of the reduction and substitution of critical materials in functional devices intended for consumers, and can be generalized to other energy-related materials and devices.
Abstract: White light emitting diodes (wLEDs) have become, in the last decade, the most efficient device for most lighting applications. They are mainly composed of indium and gallium for the blue emitting LED, and rare-earth elements for the phosphor producing the yellow component of the white light. Those elements are crucial to achieve the excellent lighting properties of wLEDs, but they are systematically ranked among the most critical materials. In the present review, the essential roles of indium, gallium and rare-earth elements in wLEDs are specified, and their criticality through the main criteria of supply shortage risk and economic importance is discussed in detail in the light of the wLED market. The opportunities and technological challenges of their reduction using nano-sized objects and substitution using non-critical materials are considered in relation to the resulting changes in the performance of wLEDs, but also to the stated preference of consumers of the final product, creating an opportunity for trade-offs between the performance and avoidance of critical materials in wLEDs. The economic value that a consumer could place in a critical material-free wLED is further estimated through a choice experiment conducted with 297 consumers. The results obtained show a positive, significant willingness to pay for critical material-free wLEDs. On average, consumers are ready to pay €2.82 more for a wLED sold at €10. The present approach addresses the transdisciplinary problem of the reduction and substitution of critical materials in functional devices intended for consumers, and can be generalized to other energy-related materials and devices.
29 citations
Additional excerpts
...Its market could be stabilized by new methods of recycling In-rich flat panel displays [38], as well as by emerging substitute materials [39]....
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TL;DR: Tb3+-activated Sr2P2O7 phosphor samples were prepared via the co-precipitation route as discussed by the authors, and the phase structure and vibrational characteristics of the synthesized phosphors were confirmed by X-ray diffraction and Fourier transform-infrared spectroscopy, respectively.
19 citations
22 Jan 2021
Abstract: As display devices based on liquid crystals have matured over the last decades, liquid crystal research has shifted its priorities in slightly different directions, such as sensors, photonics, nanotechnology and even more biologically related fields like drug delivery. This implied a change of emphasis in the development of novel materials, of which a completely new class of liquid crystal based composites emerged, that of nanoparticle-dispersed liquid crystals. The underlying ideas were to add functionality, while maintaining switchability, and the exploitation of liquid crystal self-organisation to build hierarchical nanostructures. Of particular interest for applications are dispersions of carbon nanomaterials, such as fullerenes, nanotubes and the graphene variants, due to their interactions with conventional liquid crystals. While such systems have been investigated for the past two decades, we concentrate in this review on the effects of dimensionality of the dispersed carbon nanoparticles, which goes hand in hand with the more recent developments in this field. Examples are the doping of 0D fullerenes in liquid crystals and implications for Blue Phase stability, or 1D nanotubes in nematic and ferroelectric liquid crystals, questions of dispersibility and applications as alignment media in ITO-free devices. Graphene (2D) and especially graphene oxide are mainly investigated for their formation of lyotropic liquid crystals. We here discuss the more recent aspects of dispersion in thermotropics.
14 citations
10 Dec 2020
TL;DR: In this article, the main contenders for new electrode technologies are discussed with an emphasis placed on carbon-based materials for liquid crystal displays, including composite approaches, and the advantages and disadvantages of ITO-free technologies with application examples given.
Abstract: Indium tin oxide (ITO)-free optoelectronic devices have been discussed for a number of years in the light of a possible indium shortage as demand rises. In particular, this is due to the largely increased number of flat panel displays and especially liquid crystal displays (LCDs) being produced for home entertainment TV and mobile technologies. While a shortage of primary indium seems far on the horizon, nevertheless, recycling has become an important issue, as has the development of ITO-free electrode materials, especially for flexible liquid crystal devices. The main contenders for new electrode technologies are discussed with an emphasis placed on carbon-based materials for LCDs, including composite approaches. At present, these already fulfil the technical specifications demanded from ITO with respect to transmittance and sheet resistance, albeit not in relation to cost and large-scale production. Advantages and disadvantages of ITO-free technologies are discussed, with application examples given. An outlook into the future suggests no immediate transition to carbon-based electrodes in the area of LCDs, while this may change in the future once flexible displays and environmentally friendly smart window solutions or energy harvesting building coverings become available.
5 citations
TL;DR: In this paper , an orderly, manual LCD dismantling line is put into operation for differentiated recycling of electronic boards, cold cathode lamps that may contain mercury, polymers, metals, and other valuable materials.
Abstract: For several decades, Liquid Crystal Displays (LCDs) have been widely used in televisions, laptops, mobile phones, and other devices. Nowadays, liquid crystals (LCs) represent an important economic value of the recycling system of LCDs. The reuse of these organic molecules could become a profitable basis since it permits to preserve the value of these materials. In this context, the general objective of this work focuses on the recovery of LCs as well as on other valuable materials present in end-of-life LCDs. An orderly, manual LCD dismantling line is put into operation for differentiated recycling of electronic boards, cold cathode lamps that may contain mercury, polymers, metals, and other valuable materials. There is also an extraction line where LCD panels are opened and exposed to an ultrasonically activated organic solvent bath to recover LCs. The resulting solution contains LCs, solvent, organic and inorganic impurities. The LCs mixtures were purified and then characterized mainly by spectroscopic, chromatographic, and thermal techniques. A study of the influence of adding diamond nanoparticles at 0.05, 0.1 and 0.2 wt% to recycled LCs was also performed using dielectric spectroscopy. Dielectric properties of LCs were measured at room temperature, using an impedance analyzer in the frequency range from 0.1 to 106 Hz.
3 citations
References
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TL;DR: There have been parallel and collaborative exchanges between academic research and industrial developments since the materials were first reported in 1914, it is demonstrated.
Abstract: In contrast to a recently expressed, and widely cited, view that “Ionic liquids are starting to leave academic labs and find their way into a wide variety of industrial applications”, we demonstrate in this critical review that there have been parallel and collaborative exchanges between academic research and industrial developments since the materials were first reported in 1914 (148 references)
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TL;DR: It seems that hydrometallurgical route will be a key player in the base and precious metals recoveries from e-waste, along with purification and refining.
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TL;DR: One firm with integrated mining and processing operations produced kyanite from two hard-rock open pit mines and mullite by calcining Kyanite as mentioned in this paper, which was estimated to have been used in refractories and 10% in other uses, including abrasive products such as motor vehicle brake shoes and pads and grinding and cutting wheels.
Abstract: Domestic Production and Use: In Virginia, one firm with integrated mining and processing operations produced kyanite from two hard-rock open pit mines and mullite by calcining kyanite. Two other companies, one in Alabama and another in Georgia, produced synthetic mullite from materials mined from four sites. Each company sourced materials from one site in Alabama and one site in Georgia; these data are withheld to avoid disclosing company proprietary data. Commercially produced synthetic mullite is made by sintering or fusing such feedstock materials as kyanite or bauxitic kaolin. Natural mullite occurrences typically are rare and uneconomic to mine. Of the kyanitemullite output, 90% was estimated to have been used in refractories and 10% in other uses, including abrasive products such as motor vehicle brake shoes and pads and grinding and cutting wheels; ceramic products, such as electrical insulating porcelains, sanitaryware, and whiteware; foundry products and precision casting molds; and other products. An estimated 60% to 65% of the refractory usage was consumed by the iron and steel industries, and the remainder was used by industries that manufacture chemicals, glass, nonferrous metals, and other materials. Andalusite was commercially mined from an andalusite-pyrophyllite-sericite deposit in North Carolina and processed as a blend of primarily andalusite for use by producers of refractories in making firebrick.
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TL;DR: It is found that the demand of indium, REEs, lithium and cobalt in EEE will continuously increasing, while precious metals are decreasing because of new substitutions with less or even without precious metals.
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