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Valorization of Waste LCD and Recovery of Critical Raw Material for Circular Economy: A review
Abstract
Waste an E-waste is a global environmental issue but potential resources for Indium through urban mining and recycling, which a critical raw material for the industry has been reviewed. In the e-waste, the computer followed by spent television scarp is the second highest by volume generation invariably contains the LCD panel. Indium-tin-oxide (ITO) layer in the LCD panel is an important resource for indium which has 90 wt% In2O3 and 10 wt% SnO2 is a potential resource for indium has been focused in the discussion. Challenges and opportunities associated with LCD recycling and indium recovery have been critically reviewed. Indium a critical metal; scarce in primary sources but abundant in e-waste, critical in supply chain but crucial to green energy, lacking in recycling rate but progressive EOL waste generation, poses a threat to ecosystem/habitat but potential to circularize the economy, primarily as a by-product but potential urban mine, both a challenge and an opportunity, concurrently. Cost effective industrial process development is essential for a circular economy and urban mining notion, which can address the challenge associated with environment and energy and create the opportunity for circularizing the metal economy.
... The waste LCD panel is contributing a significant portion to the e-waste which is not only a major global environmental challenge but also a significant secondary resource for industrially important metals like indium (Akcil et al. 2019;Swain et al. 2015aSwain et al. , 2015b. A recently published report by the United Nations University (UNU) and United Nations Institute for Training and Research (UNITAR) entitled "Global E-waste Monitor 2020: Quantities, flows, and the circular economy potential" highlighted the year 2019 share of the e-waste generated from the screens and monitors was 6.7 million Mt (metric ton) versus total e-waste of 53.6 million Mt (Forti et al. 2020). ...
... Zhang et al. have reported the recycling of indium from waste LCD by non-crushing leaching using ultrasonic wave (Zhang et al. 2017b). Whence, the majority of the researchers in the literature reported have used crushed waste powder to recover indium using various techniques, broadly pyrometallurgical processes, hydrometallurgical processes, and bio-hydrometallurgical processes which have been reviewed elsewhere (Akcil et al. 2019;Moroney 2017;Zhang et al. 2015). Recycling of LCD followed by dismantling reported by various authors in the open literature using various techniques is summarized in Table 1 through a brief review of the literature. ...
... Supplementary information (SI) Fig. 1(a) shows a common schematic for the LCD and exhibits the layered structure of LCD construction and constituents. Detail of the structure and constituent has been discussed elsewhere (Akcil et al. 2019). The SI Fig. 1, indicates in the LCD panel, one ITO layer is sandwiched between the back TFT glass substrate and liquid crystal layer, and one ITO layer is sandwiched between the back liquid crystal layer and front glass color Fig. 6 a SEM, filter. ...
Currently, more than 55% of global indium production is consumed for indium tin oxide (ITO) production because of its excellent display properties mainly driven by demand for flat panel displays (FPDs) or LCDs. At the end of life, the waste LCD flows to the e-waste stream, accounts for 12.5% of the global e-waste, and is forecasted to be increasing progressively. These waste LCDs are potential wealth for indium that poses a threat to the environment. The volume of waste LCD generation is a global as well as national concern from a waste management perspective. Techno-economical recycling of this waste can be a panacea to the challenges associated with the lack of commercial technology and extensive research. Hence, a mass production capable of beneficiation and classification of ITO concentrate from waste LCD panels has been investigated. The mechanical beneficiation process for waste LCDs consists of five steps of operation, i.e., (i) size reduction by shredding by jaw milling, (ii) further size reduction to feed for ball milling, (iii) ball milling, (iv) classification to enrich ITO concentrate, and (v) characterization ITO concentrate and confirmation. The bench-scale process developed is intended to integrate with our indigenously developed dismantling plant (which can handle 5000 tons per annum) to handle separated waste LCD glass for indium recovery. Once scaled up, it can be integrated for continuous operation synchronized with the LCD dismantling plant.
... As this heterogeneity makes it difficult to recycle waste LCD glass as a raw material, most of it is landfilled. Owing to the importance of indium as a raw material, various pyrometallurgical processes have been introduced to recover indium from waste LCD glass, but they also face various problems from the viewpoints of efficiency, environment, energy, etc. [4]. Nevertheless, the construction industry can offer a potential solution for recycling waste LCD glass. ...
... An LCD panel comprises a liquid crystal between two glass substrates on which a TFT and color filter plate are attached, as shown in Fig. 1 [4]. General oxide TFT consists of indium-gallium-zinc-oxide (IGZO). ...
... As Na 2 O is soluble in Fig. 1. Structure of LCD panel [4]. aqueous solutions, CaO is added to enhance its insolubility [30]. ...
As the demand for display devices increases, the disposal of liquid crystal display (LCD) glass waste becomes an emerging issue. It is thus necessary to make efforts to recycle bulk LCD glass waste. The construction industry can propose a solution to this by using LCD glass waste as an alternative resource for construction materials. This paper presents a state-of-the-art review on the utilization of liquid crystal display (LCD) glass waste as replacements for cement and fine aggregate. Its applications in special types of concrete, e.g., ultra-high-performance concrete (UHPC), self-consolidating concrete, and geopolymers, are also evaluated. Thanks to the high pozzolanicity with abundant alumina, the LCD glass powder can partially replace the cement in a classical concrete and filler of UHPC. The matrix modified with the LCD glass powder is effective in improving the medium- to long-term mechanical strength (generally at a replacement level of up to 10% or 20%) and the overall durability, with respect to alkali-silica reaction expansions, sulfate attacks, and chloride ion penetration, and freeze–thaw, as well as the pull-out resistance. However, the alternative use of LCD glass powder in metakaolin negatively affects the mechanical strength of the geopolymer, owing to the increased heterogeneity, pore size, and volume. The use of LCD glass waste as sand decreases the mechanical strength in general but leads to better workability, durability, and volume stability. Thus, LCD glass waste can be used as a new alternative ingredient for concrete, i.e., as a replacement for cementitious materials or sand.
... Numerous attempts have been made to recover indium from ITO scraps for mitigating indium resource crisis. Pyrometallurgical recycling techniques such as vacuum-chlorinated separation and vacuum carbonization reduction are able to effectively recover indium from ITO scraps, but the processes are generally lengthy, energy intensive, and carbon inefficient [11][12][13]. On the other hand, a hydrometallurgical process mainly consists of three essential steps, including leaching (acid, organic acid, alkali, etc.), separation/purification (solvent extraction, adsorption, ion exchange, etc.), and metal recovery (cementation, precipitation, reduction, etc.). ...
... In comparison with pyrometallurgical processes, hydrometallurgical processes generally have the advantages of flexibility in production scale, less energy consumption and production costs, and negligible waste gas emission. However, hydrometallurgical processes are commonly faced with waste water disposal issues, and more importantly, the leaching of ITO scraps generally generates very dilute indium-containing solutions, resulting in technical difficulties in the following separation/purification procedure for selective indium recovery [11,[14][15][16]. ...
In this work, a fundamental study on the electrochemical behavior of indium on a molybdenum electrode in the molten NaCl-KCl eutectic system at 750 °C was carried out. A variety of transient electrochemical techniques such as cyclic voltammetry, chronopotentiometry, square wave voltammetry, and linear sweep voltammetry were utilized to clarify the redox mechanism of indium in the molten melt. The results showed that the reduction of In(III) to metallic In is a diffusion-controlled one-step process of reversibility. The diffusion coefficient of In(III) in the eutectic NaCl-KCl system at 750 °C was evaluated by cyclic voltammetry and chronopotentiometry, and the results obtained by the two electrochemical methods accord well with each other, as to be approximately 1.05×10⁻⁵ and 3.7×10⁻⁵ cm²/s, respectively. This study aims to provide a theoretical basis for the development of an efficient and cost-effective process for indium secondary resources recycling on the basis of molten salt electrochemistry.
... Both circular economy and reverse logistics appreciate WEEE reuse, as it is an appropriate way to deal with the input supply chain, through increasingly available technologies, and to maximize the reuse of waste or part of it after the life cycle. The economic development of these industrial processes creates the opportunity for inserting these materials in a circular economy (Akcil, Agcasulu & Swain, 2019), since its strategies encourage the extension of products' useful life, among other actions (Vanegas, Peeters, Cattrysse, Paolo Tecchio, Ardente, Mathieux, Dewulf & Duflou, 2018). ...
... Therefore, we can assume that there is a great market potential related to the reverse logistics of WEEE and end-of-life EEE, as a source of raw material, and which still has to be explored in Brazil, creating new jobs and income. As raw materials are crucial for industrial growth and competitiveness, regarding critical metals, the circular economy is vital for processing, reusing, recycling and recovering sustainable technologies (Akcil, Agcasulu & Swain, 2019). ...
Purpose
The purpose of the article is to analyze the chain of electrical and electronic equipment (EEE) and its waste (WEEE), within the product chain of Recicladora Urbana (Reurbi), and its interaction with the circular economy.
Design/methodology/approach
Exploratory research with a qualitative approach, based on the study case method, was conducted. The following stages were carried out: definition of the study object; bibliographic survey; documentary survey; technical visit to Reurbi; contacts with experts; creation of research instruments and research execution.
Findings
The main recipients of remanufactured EEE are third sector organizations that run social programs and schools with few financial resources. Recycling firms receive parts and components from the WEEE handled by Reurbi.
Research limitations/implications
The authors only addressed the WEEE reverse remanufacturing chain of Reurbi; therefore, the authors cannot extend the results to an industrial sector.
Practical implications
One practical contribution is disclosing the remanufacturing processes of EEE and the recycling processes of its waste, fostered by the National Solid Waste Policy (PNRS), under a circular economy policy.
Social implications
There is a large market potential for reverse logistics of WEEE and end-of-life EEE as a source of raw material, which is yet to be explored in Brazil, for creating new jobs and revenue.
Originality/value
The publication of articles with the main reflections from the results can provide new discussions and provide opportunities for new studies regarding the Brazilian Solid Waste Policy.
... The electronic waste stream comprises a variety of materials, including both valuable ones like steel, palladium, iron, aluminium, silver, gold, platinum, copper, and polymers, as well as hazardous ones like polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), mercury, polybrominated biphenyls (PBBs), along with lead, that can't be dumped of in landfills (Kumar et al., 2017;Akcil et al., 2019;Tutton et al., 2022). In accordance with the research conducted by Shi et al. (2020), E-waste deconstruction operations have caused a spike in the amounts of copper (Cu), nickel (Ni), cadmium (Cd), zinc (Zn) and lead (Pb) in paddy soils in China. ...
... The topic of life cycle assessment [70,85] holds the second position in terms of page rank value, but its low betweenness centrality indicates that it does not serve as a link between other topics. This cluster also contains the following topics: cleaner production [86][87][88], exergy [67,89], recycling [90,91], climate change [92,93], global warming [94], environmental impact [95,96], energy efficiency [97,98], energy transition [99,100], industry 4.0 [101], anaerobic digestion [102,103], bioenergy [104,105], biogas [58,104,105], and solar energy [106,107]. Compared to solar energy, wind energy, and hydropower, bioenergy appears the most frequently in the author's keywords in the article database regarding the application of renewable energy in the circular economy framework. ...
Over the past half-century, scientists from many different areas have been investigating how to switch to renewable energy, especially in the context of a circular economy. Numerous articles have discussed the scientific aspects of developing technology to support this process. This systematic literature review and bibliometric study aim to fill in research gaps by looking at trends, challenges, and possible future directions for the use of renewable energy in the context of a circular economy, especially in the fields of business, management, and economics. The study analyzed 294 peer-reviewed articles using the R Studio-Biblioshiny package version 4.1.2 software. The challenges of integrating renewable energy technologies within a circular economy include financial constraints, such as a high initial investment, the lack of an adequate regulatory framework and government support, the intermittent availability of renewable energy sources, the scarcity of resources and components for renewable energy generation technologies, relatively low energy conversion efficiency, the challenge of increasing consumer awareness, and the environmental impact of technological waste. The study suggests that future research should focus on financial models and policy incentives that can encourage businesses and investors to take advantage of renewable energy. The study also recommends exploring sustainable alternative fuel technologies, optimized waste-to-energy conversion, the increased efficiency of bioenergy conversion, more efficient solar panels, improved energy storage capacity, the life cycle management of solar panel devices, and the development of innovative business models to facilitate industrial symbiosis.
... 9 LCD screens are commonly used for recovering their component materials like glass, plastic, and valuable metals like silver (Ag), copper (Cu), nickel (Ni), indium (In), etc. 10 LCD panels consist of a liquid crystal film sandwiched between two glass plates and a conductive indium tin oxide (ITO) film coated on the inner surface of the glass plate. 11 The ITO film renders a transparent structure and electrical conductivity to LCDs. Moreover, the surface functional groups such as NH 2 , C�O, O−C, and C−O−C act as conductive sites on the LCD surface, 12 which lowers the thickness of the electric double layer and the activation energy barrier at the electrode surface. ...
... Regarding LCDs, the estimated production of LCD-based e-waste products in Europe in 2020 was close to 399 kt for TVs, 194 kt for monitors, and 97 kt for notebooks (Cucchiella et al., 2015). These data depict the rapid diffusion of LCD in the market, as they present an integral part of all types of electronic devices, such as TV units, laptops, monitors, mobile phones, equipment displays, and billboards, as screens (Akcil et al., 2019). Although LCDs have less environmental impact than cathode ray tubes (CRT), some of the elements embedded in LCDs, such as Cr, Cd, Pb, and Hg, are hazardous to the environment and human health (Savvilotidou et al., 2014). ...
Currently, electronic waste (e-waste) is grossly overproduced and only a few recycling programs exist. Improper e-waste destinations have a negative impact on the environment and human health because they contain several potentially toxic substances. Scientific publications on this topic have also grown over the years, necessitating a systematic literature review to identify trends and gaps in research. We performed a systematic review of the scientific literature on the toxic effects of e-waste and its adverse environmental impacts. We searched the literature using the Web of Science and Scopus databases , and 335 articles were selected after applying the exclusion criteria. The e-waste class most studied in the articles was the small IT and Telecommu-nication equipment, and the trashes most cited were cell phones, printed circuit boards, and liquid crystal display (LCD) panels. The heavy metals most associated with toxicity were Pb and Cd, whereas polybro-minated diphenyl ethers were the most cited organic components. In addition, we identified the different uses of bioassays to evaluate the toxic potential of e-waste in soil and water. In contrast, a few articles introduced alternative strategies for e-waste toxicity by bioremediation and educational research. Regarding human exposure, all articles demonstrated the hazardous effect of e-waste on health; however, studies include methodological difficulties, such as short-term surveys with a few volunteers, various pollutants , and different evaluated endpoints. These data gaps in the evaluation of exposure and long-term effects will narrow when collaborative studies including distinct fields are published, and the involvement of government agencies will regulate the production, discard, and recycle electronic wastes.
... The sandwich layer has a front vertical light polarizer and a rear horizontal light polarizer followed by a reflector layer. The reflected light cannot pass through the adapted molecules, and the activated segment appears to darken and forms the character of the data to be displayed [18]. ...
Traditional medicines are ingredients or ingredients in the form of plant ingredients, animal ingredients, mineral ingredients, galenic preparations, or mixtures of these materials, which have been used for generations for treatment and can be applied according to the norms in force in society. Bottle shark (Centrophorus atromarginatus) has good prospects as a producer of liver oil; this fish is easy to catch and occurs in relatively large quantities in Indonesian waters. The catch rate until now is only 39% of its sustainable potential. Bottled shark liver oil contains 90% squalene, Vitamin A, and Omega, which are very useful for the human body as a supplement for heart disease and stomach ulcers and increase stamina and brain intelligence. The rapid Development of technology certainly benefits the people who use it. One example of today's use of technology is applying a technology system for the fisheries sector. This tool works automatically to monitor the processing of bottled shark livers. That way, fishermen don't have to worry about cloudy weather or things that will take longer than processing the shark liver bottle. This Bottle Shark Liver Heater uses temperatures at 31˚, 32˚, 33˚, 34˚, and 35˚. With PID (Proportional Integral Derivative) control, the quality of the Bottle Shark liver can be maintained. This tool is supported by a DS18B20 temperature sensor, Arduino uno, Relay, Ceramic Heater element, DC Fan, LCD 16X12, Power Supply, and Switch. It is hoped that the community, with this automatic system device, can make it easier to manage Bottle Shark Liver Oil.
... Excluding premature device replacement, the lifetime of a LCD is approximatively ten years [8]. Televisions, computers and tablets based on LC technologies includes a set of high value-added materials whose recycling represents a strategic issue [9]. ...
... In addition, precious metals may be lost due to slag formation during pyrometallurgy (Chauhan et al., 2018). The hydrometallurgical approach has advantages such as negligible emission of hazardous gases, less energy requirement, lesser initial investment, lower operating cost, and selective metal recovery with high efficiency (Akcil et al., 2019). The current hydrometallurgical approaches use different leaching agents (e.g., cyanide, acid, alkali, halide, thiosulfate, thiourea, etc.) to extract metals from e-waste (Birloaga and Vegliò, 2022;Mir and Dhawan, 2022;Niu et al., 2022). ...
The rapid increase in electronic waste (e-waste) generation and its unsustainable management pose a threat to the environment and human well-being. However, various valuable metals are present in e-waste, which makes it a potential secondary source to recover metals. Therefore, in the present study, efforts were made to recover valuable metals (Cu, Zn, and Ni) from waste printed circuit boards (WPCB) of computers using methanesulfonic acid (MSA). MSA is contemplated as a biodegradable green solvent and has a high solubility for various metals. The effect of various process parameters (MSA concentration, H2O2 concentration, stirring speed, liquid to solid ratio, time, and temperature) was investigated on metal extraction to optimize the process. At the optimized process conditions, 100% extraction of Cu and Zn was achieved, while Ni extraction was around 90%. The kinetic study for metal extraction was performed using a shrinking core model and findings showed that MSA-aided metal extraction is a diffusion-controlled process. Activation energies were found to be 9.35, 10.89, and 18.86 kJ/mol for Cu, Zn, and Ni extraction, respectively. Furthermore, the individual recovery of Cu and Zn was achieved using the combination of cementation and electrowinning, which resulted in 99.9% purity of Cu and Zn. The current study proposes a sustainable solution for the selective recovery of Cu and Zn from WPCB.
... In addition to recycling, there are methodologies to extend the useful life of products and recover values from WEEE (Garrido-Hidalgo et al. 2020). For example, indium, a critical metal that is scarce in primary sources but abundant in e-waste, represents both a supply chain risk and mitigated opportunity (Akcil et al. 2019). Nowadays, product refurbishment is one of the most profitable and environmental benefit processes, drawing more and more attention from both product manufacturers and customers (Chen et al. 2018). ...
Electronic waste (e-waste) is gaining the attention of scholars since its supply chain offers valuable materials that can be recovered, generating resilience to supply chains and the environment. To recover these materials, it is necessary to establish closed-loop supply chains, enabling a circular economy logic. In this sense, supply chain flows must be designed to retrieve these values and mitigate the risks. Furthermore, collection points must be strategically positioned to make this operation feasible, integrating the concept of smart cities. Therefore, this article proposes a conceptual analysis of the literature and, as its main result, presents an integrated framework considering five dimensions: (i) E-waste management, (ii) Supply Chain Resilience—SCRes, (iii) Circular Economy, (iv) Closed-loop supply chains, and (v) Smart cities.
KeywordsE-Waste managementSupply chain resilienceCircular economyClosed-loop supply chainsSmart cities
... In addition to recycling, there are methodologies to extend the useful life of products and recover values from WEEE (Garrido-Hidalgo et al. 2020). For example, indium, a critical metal that is scarce in primary sources but abundant in e-waste, represents both a supply chain risk and mitigated opportunity (Akcil et al. 2019). Nowadays, product refurbishment is one of the most profitable and environmental benefit processes, drawing more and more attention from both product manufacturers and customers (Chen et al. 2018). ...
E-waste management is becoming a very challenging subject since it is very multidisciplinary, encompassing concepts such as circular economy, closed-loop supply chains, supply chain risk management, and supply chain resilience. These pillars must be strongly supported by a huge amount of quality data, therefore, opening an important interface with the concept of smart cities. Among the main challenges, is the need to motivate the customers to collaborate, creating a culture of reusing and recycling end-of-life products. In addition, it is crucial to develop reverse recycling channels suitable to each client and enabled by an effective logistics network design. Despite the relevance of this topic, many significant gaps can be pointed out, since there are still few relevant papers. Thus, there is a substantial necessity of understanding what have been done by scholars to establish the state of the art. In this sense, this paper has the objective of mapping the state of the art of e-waste management through a bibliometric study. Among the main results, we highlight the mapping of the state of the art composed of the literature statistics.
... The circular economy (CE) concept is a closed cyclic concept that is designed and aims to achieve maximum utilization of the products and their value and ensures 4R's (Reduce, Reuse, Recycle, and Recovery) concept (Geissdoerfer et al., 2017;Akcil et al., 2019). Implementation of the CE concept instead of the linear economic model enhances the natural capital, optimization of resource yields, minimizing the risks in the system and the environment through proper management policies (Arya and Kumar, 2020). ...
E-waste management has become a global concern because of the enormous rise in the rate of end-of-life electrical and electronic equipment's (EEEs). Disposal of waste EEE directly into the environment leads to adverse effects on the environment as well as on human health. For the management of E-waste, numerous studies have been carried out for extracting metals (base, precious, and rare earth) following pyrometallurgy, hydrometallurgy, and biometallurgy. Irrespective of the advantages of these processes, certain limitations still exist with each of these options in terms of their adoption as treatment techniques. Several journal publications regarding the different processes have been made which aids in future research in the field of E-waste management. This review provides a comprehensive summary of the various metal recovery processes (pyrometallurgy, hydrometallurgy, and biometallurgy) from E-waste, along with their advantages and limitations. A bibliometric study based on the published articles using different keywords in Scopus has been provided for a complete idea about E-waste with green technology perspective like bioleaching, biosorption, etc. The present study also focussed on the circular economic approach towards sustainable E-waste management along with its socio-economic aspects and the economic growth of the country. The present study would provide valuable knowledge in understanding E-waste and its different treatment processes to the students, researchers, industrialists, and policymakers of the country.
... This has led to the generation of significant amounts of waste electrical and electronic equipment (WEEE) [5,6]. WEEE includes but is not limited to worn-out integrated circuit (IC) manufacturing and computer industry products, printed circuit boards (PCBs), connectors, wiring, metal housings, as well as batteries and fluorescent lamps [7][8][9][10]. ...
... 12 This has allowed its implementation in technologies such as optoelectronics, 13 sensors and biosensors, 14 and photovoltaics, 15 among others. 16 Beyond the technological advantages, ITO production involves a significant use (55%) of the worldwide available indium, 17 an amount that is expected to grow due to indium involvement in critical and demanding sectors, mainly in electronic devices for liquid crystal displays (LCDs). 18 Thus, attempts have been carried out to recover ITO after a device's useful life. ...
... Indium is widely considered a strategic material because of its increasing demand as indium-tin-oxide (ITO) in audiovisual technologies, optoelectronic systems, semiconductors and photovoltaic solar cells (Akcil et al., 2019;Schulz et al., 2017). Thus, a continuous indium increase in demand and consumption for high-tech applications has caused this metal to reach the top critical material classification. ...
The indium recovery via electrowinning from sulfate baths has recently gained significant attention due to the absence of toxic emissions, sealed-system requirements, human health and environmental hazards. In the present research, Ni has been considered as a cathode for indium electrowinning from sulfate baths. The influence of process parameters, temperature, pH, current density, electrolyte composition and additive additions on specific energy consumption (SEC), current efficiency (CE), as well as deposit morphology has been evaluated. The findings indicate that the indium electrowinning using Ni cathode at 40 °C temperature, 2.3 pH, 70 g/L In³⁺ as sulfate, 5 g/L H3BO3, 30 g/L Na2SO4 and 20 g/L Al2(SO4)3 electrolyte composition maintained a high CE of about 98% and low SEC of about 1.7 kWh/kg from 25 to 80 A/m² current density. While increasing current density up to 100 A/m², a maximum of about 83.3% CE with 2.4 kWh/kg SEC are obtained if 40 g/L and 30 g/L of boric acid and sodium sulfate are used, respectively. In the optimized conditions, indium deposits exhibited a lamellar morphology and crystallographic tetragonal structure.
... The pyrometallurgy, hydrometallurgy and biohydrometallurgy have been investigated for the recovery of metals from e-waste [9,10]. Pyrometallurgy employs incineration, roasting, smelting and calcination at higher temperature (>1000 • C) for the recovery of metals [11]. Few industrial plants such as Ronnskar smelter in Sweden, Umicore in Belgium, Noranda copper smelter in Canada and Aurubis in Germany are using pyrometallurgy for the recovery of metals from e-waste. ...
(Link to access full article: https://authors.elsevier.com/c/1eKR27sxn0bz~h)
The study investigated the non-isothermal co-pyrolysis of Sargassum wightii (macroalgae) with electronic waste in the temperature range of 50–800 °C using a thermogravimetric analyser in an inert nitrogen atmosphere. Using the thermogravimetric analysis data, the synergistic influence of macroalgae on electronic waste and vice versa was evaluated by considering thermal decomposition behavior, the degree of thermal degradation and kinetics as evaluation criteria. The thermogravimetric analysis revealed the presence of three different decomposition stages (50–150, 150–550 and 550–800 °C) for all the samples and their blends. The second stage, which is considered as a major pyrolysis zone witnessed maximum weight loss in all the cases. While the decomposition of structural components can be attributed to the major weight loss with macroalgae, the thermal decomposition of polymeric fraction along with brominated and non-brominated epoxy resins could be the reason for weight loss with electronic waste in the second zone. The thermogravimetric data via isoconversional method was interpreted to evaluate the kinetic triplet for the co-pyrolysis process. The kinetic analysis indicated that the activation energy varied significantly with respect to the conversion in the range 0.1–0.8. Furthermore, the values obtained in this study for the kinetic parameters correspond to those reported in the literature. The synergistic impact of macroalgae on electronic waste and vice versa was clearly evident in terms of thermal degradation pattern, residues and reaction kinetics. The obtained thermodynamic and kinetic parameters demonstrated the co-pyrolysis of macroalgae and electronic waste as a potential pathway to harness bioenergy and ease the optimization of macroalgae co-pyrolysis with other similar feedstocks.
... However, indium is considered as the most desired metal since it occurs in a higher amount in LCD waste. The studies conducted on the leaching of In from LCD panels in the last decade have been reviewed and can be found elsewhere [43,44,72]. ...
There is a growing interest in electronic wastes (e-wastes) recycling for metal recovery because the fast depletion of worldwide reserves for primary resources is gradually becoming a matter of concern. E-wastes contain metals with a concentration higher than that present in the primary ores, which renders them as an apt resource for metal recovery. Owing to such aspects, research is progressing well to address several issues related to e-waste recycling for metal recovery through both chemical and biological routes. Base metals, for example, Cu, Ni, Zn, Al, etc., can be easily leached out through the typical chemical (with higher kinetics) and microbial (with eco-friendly benefits) routes under ambient temperature conditions in contrast to other metals. This feature makes them the most suitable candidates to be targeted primarily for metal leaching from these waste streams. Hence, the current piece of review aims at providing updated information pertinent to e-waste recycling through chemical and microbial treatment methods. Individual process routes are compared and reviewed with focus on non-ferrous metal leaching (with particular emphasis on base metals dissolution) from some selected e-waste streams. Future outlooks are discussed on the suitability of these two important extractive metallurgical routes for e-waste recycling at a scale-up level along with concluding remarks.
... • Raw materials are crucial for strong industrial growth and competitiveness; therefore, circular economy is vital for sustainable processing, reuse, recycling, and recovery of critical metals. Akcil et al. (2019) 2015). However, long processing times (i.e., 20-40 days) and low yields make improvements necessary (Chen et al., 2008;Zheng et al., 2014). ...
Due to the recent boom in urbanisation, economy, and global population, the amount of waste generated worldwide has increased tremendously. The World Bank estimates that global waste generation is expected to increase 70% by 2050. Disposal of waste is already a major concern as it poses risks to the environment, human health, and economy. To tackle this issue and maximise potential environmental, economic, and social benefits, waste valorisation – a value-adding process for waste materials – has emerged as a sustainable and efficient strategy. The major objective of waste valorisation is to transit to a circular economy and maximally alleviate hazardous impacts of waste. This review conducts bibliometric analysis to construct a co-occurrence network of research themes related to management of five major waste streams (i.e., food, agricultural, textile, plastics, and electronics). Modern valorisation technologies and their efficiencies are highlighted. Moreover, insights into improvement of waste valorisation technologies are presented in terms of sustainable environmental, social, and economic performances. This review summarises highlighting factors that impede widespread adoption of waste valorisation, such as technology lock-in, optimisation for local conditions, unfavourable regulations, and low investments, with the aim of devising solutions that explore practical, feasible, and sustainable means of waste valorisation.
... In China, the estimated ewaste was 5.52 million tons in 2013 and 11.7 million tons in 2020 and expected increases is 20 million tons in 2040 [10]. The LCD e-waste increases globally per year and two times faster than other e-waste and it could be 52.2 million metric tons in 2021 [11]. The heavy toxic like polycyclic aromatic hydrocarbons (PHAs), polychlorinated biphenyls (PCBs) and polychlorinated dioxins (PCDs) are dangerous for the environment during incineration process [12]. ...
Recycling of materials can play an important role in sustainable environment and in the development of economy. In accordance with this generalized sustainable practice, the feasibility study of using non-metallic fractions (NMFs) from waste liquid crystal displays (LCDs) with waste polyethylene terephthalate (PET) bottles to produce a valuable composite material was carried out. Different composition of LCD-PET composite material was investigated in terms of mechanical strength properties and examination of composite fracture surfaces. The acquired results showed that the mechanical properties such as tensile strength, bending strength, impact strength and modulus of LCD-PET composites is improved by increasing of NMFs of LCDs. The optimum results of mechanical strength properties reflected in morphologies of fractured surface was obtained at 70 %wt of NMFs. At optimized weight ratio of NMFs in LCD-PET composite samples, tensile strength (0.46 MPa), tensile modulus (0.35 MPa), bending strength (2.09 MPa), bending modulus (14.15 MPa) and impact energy (0.74 J) was achieved. The improved value of these properties are due to strong adhesion bonding between particles of NMF and PET. This research suggests that the utilization of NMFs of waste LCDs with PET will result in the substantial reduction of environmental pollution.
... The amount of WEEE generated varies between countries and depends mainly on economic and technological developments, consumption levels, and the availability of EEE equipment, and it is expected to increase systematically regardless of the discrepancies [5]. Electronic scrap is diverse; it includes spent products used in the production of integrated circuits, PCB, connectors, wiring, etc., as well as batteries and fluorescent lamps [6,7]. WEEE contains many different hazardous components that can be released during improper storage or processing, posing a threat to human health and the environment [8], as well as valuable precious metals, such as gold or silver, the recovery of which is desirable [7][8][9][10]. ...
In this article, the application of a polymer film containing the ionic liquid Cyphos IL 101
for the simultaneous recovery of precious and heavy metal ions ((Ni(II), Zn(II), Co(II), Cu(II), Sn(II), Pb(II), Ag(I), Pd(II), and Au(III)) from waste electrical and electronic equipment (WEEE) is described. The experiments were performed for solutions containing metal ions released from computer e-waste due to leaching carried out with concentrated nitric(V) acid and aqua regia. It was found that the applied polymer film allows for the efficient recovery of precious metals (98.9% of gold, 79.3% of silver, and 63.6% of palladium). The recovery of non-ferrous metals (Co, Ni, Cu, Zn, Sn, and Pb)
was less efficient (25–40%). Moreover, the results of the performed sorption/desorption processes show that the polymer film with Cyphos IL 101 can be successfully used after regeneration to recover metals ions several times.
... Conventional CRT glass recycling is carried out in a closed-loop, where waste glass, after an appropriate removal of metal and luminophore contaminants, is utilized during manufacturing of new CRTs [15,16]. However, the above-mentioned recycling method is insufficient, as technology develops and modern liquid crystal display (LCD), plasma or light-emitting diode (LED) screens are introduced, the demand for CRT glass decreases [17]. As a result, it is necessary to provide the industry with new technical solutions for the processing of waste glass which led to other products than CRTs [18]. ...
This paper presents a novel approach for the recovery of lead from waste cathode-ray tube (CRT) glass by applying a combined chemical-electrochemical process which allows the simultaneous recovery of Pb from waste CRT glass and electrochemical regeneration of the leaching agent. The optimal operating conditions were identified based on the influence of leaching agent concentration, recirculation flow rate and current density on the main technical performance indicators. The experimental results demonstrate that the process is the most efficient at 0.6 M acetic acid concentration, flow rate of 45 mL/min and current density of 4 mA/cm2. The mass balance data corresponding to the recycling of 10 kg/h waste CRT glass in the identified optimal operating conditions was used for the environmental assessment of the process. The General Effect Indices (GEIs), obtained through the Biwer Heinzle method for the input and output streams of the process, indicate that the developed recovery process not only achieve a complete recovery of lead but it is eco-friendly as well.
Remanufacturing, reuse, and recycling in supply chain (RRR & Supply chain) are recently gaining significant attention from researchers. This bibliometric study aims to make overall research scenarios on RRR & Supply chain by analyzing the published papers. For a collection of exclusive papers in this area, we rely on the well-known trustworthy database SCOPUS. The bibliometric study is done by the contents of publication and citation structure of influential papers, leading authors, institutions, and countries, citation structure of top ten journals, country analysis in the area of RRR & Supply chain research. Present study reveals that S.M. Gupta has the highest number of publications, the USA is the most influential country, the renowned ‘Journal of Cleaner Production’ has published the greatest number of papers, and the Institute ‘Huazhong University of Science and Technology’ has the highest number of publications in this field. Through data mining this work revealed that closed loop supply chain, industry, waste, review, policy, circular economy, and sustainability are mostly used keywords while highly cited articles frequently used keywords like supply chain management; closed-loop supply chain; reverse logistics; article; logistics; manufacture; costs; decision making; environmental impact; and waste management. This study will help to fill the research gap and show a roadmap for future research direction in this area.
As a rare metal, indium is an important component of ITO targets in liquid crystal displays (LCDs). In order to alleviate the problem of resource loss, the recycling of indium in waste LCDs has become more and more important. In this paper, the adsorbent (CM-HPEI-HD-1) was prepared by modifying the weakly acidic macroporous resin (HD-1) with hyperbranched polyethyleneimine (HPEI) and sodium chloroacetate. The adsorbent was characterized using SEM, XRD, FTIR, TGA, and XPS. And its adsorption performance for In(iii) in the hydrochloric acid system was investigated. The experimental results showed that the maximum adsorption capacity of the CM-HPEI-HD-1 for In(iii) was 97.78 mg g⁻¹ at 35 °C. Kinetic experiments showed that the adsorption of In(iii) on CM-HPEI-HD-1 was in accordance with the pseudo-second-order kinetic model. The adsorption process is an endothermic process. The adsorption isotherm data were consistent with the Freundlich isotherm model. The cyclic performance of CM-HPEI-HD-1 was evaluated using the dynamic adsorption-desorption method. The cyclic experiments showed that the adsorption performance of the adsorbent remained basically unchanged after five adsorption-desorption cycles. The separation performance of the adsorbent for In(iii) and Sn(ii) was investigated, and it was found that the adsorbent had a better adsorption performance for In(iii). In addition, the adsorption mechanism of In(iii) on CM-HPEI-HD- was investigated based on XRD and XPS. It was found that both carboxyl groups and amine groups interact with In(iii).
The copper recovery from waste printed circuit boards is of great significance to protect natural resource and environment. Direct current electrodeposition has been applied to extract metal from hydrometallurgical leach solutions. However, during the direct current electrodeposition process, concentration polarization and hydrogen evolution reaction often exist, which reduces current efficiency and metal recovery capability. In this work, a pulse current was applied to electrodeposit copper. The electrolyte was the leach solution of waste printed circuit boards obtained using a sulfuric acid-hydrogen peroxide system. The influence of process parameters in the leaching stage and the electrodeposition process on current efficiency were both investigated. The results showed that the current efficiency was 95.1% in pulse current electrodeposition, while that was only 90.9% in direct current electrodeposition. The increased current efficiency was proposed to be attributed to the fact that pulse current electrodeposition could improve the mass transfer of copper ions which suppressed concentration polarization and hydrogen evolution reaction. These results demonstrate that pulse current electrodeposition is a promising approach for recovering copper from waste-printed circuit boards.
Esforços consideráveis estão sendo realizados na introdução gradual de fontes de energias sustentáveis para satisfazer as necessidades futuras de energia. A energia desempenha um papel essencial na economia circular porque as atividades circulares, como o processamento de materiais, requerem energia e calor. O objetivo foi pesquisar na literatura se a geração e o uso de energia solar fotovoltaica poderão contribuir para com os preceitos de economia circular. Foram realizadas pesquisas na base de dados ScienceDirect utilizando-se as palavras “solar and energy and circular economy”, “photovoltaic and energy and circular economy” sendo encontrados 25 artigos. Os artigos foram classificados nos temas “geração e uso de energia solar fotovoltaica”; “recuperação de material dos equipamentos de geração de energia fotovoltaica” e “comparação com a geração de outras formas de energia”. Foram localizados quinze artigos sobre “geração e uso de energia solar fotovoltaica”, oito artigos sobre “recuperação de material dos equipamentos de geração de energia fotovoltaica” e dois artigos sobre “comparação com a geração de outras formas de energia”. Verificou-se na pesquisa que a energia solar fotovoltaica, seja na geração de energia considerada uma fonte limpa e renovável, uso ou por meio de seus resíduos tanto da produção dos equipamentos ou após a vida útil, é uma tecnologia que poderá contribuir com a economia circular.
Plastics play an indispensable role in our daily lives, owing to their ease in use, low cost, strength, versatility and durability but their excessive usage in packaging industries, pharmaceuticals, agriculture and other sectors has caused severe environmental damages, raising serious concerns. Plastics’ (primary and secondary) fragmentation results in the formation of micro-and nano-plastics (MNPs). MNPs, once disposed in the environment, persist there for long duration due to their extremely poor degradability. MNPs may act as a carrier for persistent organic pollutants (POPs), thus raising environmental and human health complications. House-hold activities, improper municipal solid waste management, anthropogenic waste, and agricultural run-off, etc. are among the several aspects responsible for the accumulation of MNPs in the soil or in waterways (lakes, rivers, and finally sea). Terrestrial contamination leads groundwater contamination with leachates, causing harmful ecotoxicological impact on the rhizosphere, microbiota and plants. The current review aims to elucidate the major sources and pathways responsible for the emergence of MNPs in groundwater, ecotoxicity and human health hazards. Novel hybrid technologies that are conducive for the characterization and mitigation of MNPs have also been discussed. Furthermore, special emphasis has been laid upon the valorization of plastic wastes as a way forward for circular bioeconomy and to attain the sustainable development goals by 2030. For management of plastic waste, it is highly recommended to find sustainable alternate material and to adopt policies that regulates its usage, and suggests measures such as recycling and regeneration.
The need to increase sustainability and reduce the ecological footprint of the construction industry is leading to the search for alternative sources of raw materials. Liquid crystal display (LCD) screens have been used for many years and are also rapidly aging as a result of rapid development. Therefore, the use of the waste from LCD screens is an interesting avenue for the construction industry. This paper presents a very practical study of the use of ground material from old LCD screens to replace various fine aggregates. Fifteen concrete mixes of different strength levels and with different amounts of LCD powder were prepared. The results of density, compressive strength, and tensile strength at 7 and 28 days after concreting are presented. The results are correlated with the amount of replacement waste components and are also correlated with each other. There is a high correlation between the compressive strength of concrete and the amount of LCD waste aggregate in the form of a lognormal curve. Similarly, there is a high correlation using a lognormal curve between tensile strength and amount of LCD aggregate. The correlation between density and strength tests presented interesting results. For the 7-day data the correlations are lower, but for the 28-day results high linear correlation fits are observed. The presented data improve the understanding of the practical application of LCD waste aggregate in concrete.
The recovery of strategic metals such as rare earth elements (REEs) requires the development of new sorbents with high sorption capacities and selectivity. The bi-functionality of sorbents showed a remarkable capacity for the enhancement of binding properties. This work compares the sorption properties of magnetic chitosan (MC, prepared by dispersion of hydrothermally precipitated magnetite microparticles (synthesized through Fe(II)/Fe(III) precursors) into chitosan solution and crosslinking with glutaraldehyde) with those of the urea derivative (MC-UR) and its sulfonated derivative (MC-UR/S) for cerium (as an example of REEs). The sorbents were characterized by FTIR, TGA, elemental analysis, SEM-EDX, TEM, VSM, and titration. In a second step, the effect of pH (optimum at pH 5), the uptake kinetics (fitted by the pseudo-first-order rate equation), the sorption isotherms (modeled by the Langmuir equation) are investigated. The successive modifications of magnetic chitosan increases the maximum sorption capacity from 0.28 to 0.845 and 1.25 mmol Ce g−1 (MC, MC-UR, and MC-UR/S, respectively). The bi-functionalization strongly increases the selectivity of the sorbent for Ce(III) through multi-component equimolar solutions (especially at pH 4). The functionalization notably increases the stability at recycling (for at least 5 cycles), using 0.2 M HCl for the complete desorption of cerium from the loaded sorbent. The bi-functionalized sorbent was successfully tested for the recovery of cerium from pre-treated acidic leachates, recovered from low-grade cerium-bearing Egyptian ore.
From this e-book, it can be concluded that even though a wide variety of novel and innovative building materials using C&DW has been developed worldwide, more incentives are required (e.g.through public policies) to really convert the local and national construction sectors in sustainable businesses which appropriate the circular economy as production and consumption systems that promote, at least, the efficiency in the use of materials, water and energy. This has not only the potential to develop new sustainable business models based on research, this also might transform existing companies into more sustainable businesses, which results very important for the current economy post-pandemic scenario.
The tracking of electronic waste (e-waste) flows through and within pre-processing facilities plays a crucial role in determining the fate of resources contained in e-waste. This study maps material and economic flows of e-waste through manual and mechanical processes at the pre-processing facility using material flow analysis. Both daily and annual material flows were accounted for, and daily flow outputs were also translated into economic flows. Each day the facility mainly processed printers and peripheral devices, laser cartridges, and refurbishable flatscreen displays. The main material outputs were glass, mixed plastics, and computer and communication wires containing copper. The most valuable products were refurbished goods and the highest revenue material was copper, whereas the highest cost item was glass from cathode ray tube (CRT) displays, due to its lead content. From 2016–2018 the facility received fewer CRT displays due to both global e-waste trends, by selling and trading CRTs to other Ontario pre-processors in exchange for flatscreen displays. This approach helped the facility to capitalize new specialized equipment for the processing of flat screens and reduced downstream leaded glass processing costs. The changing product and material profile of e-waste in Canada, and globally, needs advanced technological solutions by the pre-processors to maximize resource recovery in economically feasible manner.
Recovering indium tin oxide (ITO) is crucial to alleviate the In and Sn resources shortage and eliminate environmental pollution while treating waste liquid crystal displays. Since the key to ITO recovery lies in In and Sn separation, the adsorption behavior of Sn in one-step separation was studied with a macroporous silica-based adsorbent, D2EHPA/SiO2-P, which was successfully prepared and well characterized. Based on the analysis of adsorption selectivity, adsorbent dosage, adsorption kinetics, adsorption isotherms, as well as thermodynamics and desorption performance, a new simple process was explored to solve the tedious process of several times extraction and back-extraction of D2EHPA. The batch experiments revealed that D2EHPA/SiO2-P presented significant adsorption selectivity for Sn(IV) with SFSn/other metals over 1479 mL/g in 6 M H2SO4 solution, and XPS showed that both P=O bond and P-O bond were involved in the chemical reaction as an electron acceptor during the adsorption of Sn(IV). The adsorption equilibrium was obtained within 10 min. The adsorption process was homogeneous monolayer chemisorption and endothermic chemical process. The adsorption mechanism indicated that the O-H bond in D2EHPA participated in bonding and performed a substitution reaction with free Sn(IV) ions with an energy of about 0.016 eV in the adsorption process. Furthermore, O-H in NaOH played a decisive role in the desorption process, directly bonded to the Sn atom, causing the Sn-O bond to break with an energy of about 1.738 eV.
Global transition towards low-carbon future is threatened by supply risks surrounding critical raw materials, particularly the rare, scarce, and scattered metals (RSSM) with poor mineral endowments. Thus, the metal recycling from various end-of-life products are widely advocated and advanced as a key strategy, but the present understanding of their recycling potentials, limitations and challenges is quite scattered and limited. Here, this paper conducts a literature review, based on the PRISMA analysis of approximately 160 types of relevant studies from 2010 to 2021, to provide sophisticated knowledge related to the recycling status, progress, and future directions of 34 types of RSSM. Results indicate only a part of those metals can be recycled due to the obstacles in metal design as well as societal and economic factors in its usage and recycling, and the corresponding obstacles for each metal are further identified by key factors including complexity of the product design, more complex end-use of metal, and lack of suitable infrastructure for collection. Thus, the jointed efforts from all stakeholders along metal cycle from material design, use, throughout to final recycling are highly suggested and urged to secure metal base for future circular and low-carbon economy.
Considerable efforts are being made to gradually introduce sustainable energy sources to meet future energy needs. Energy plays an essential role in the circular economy because circular activities, such as materials processing, require energy and heat. The objective was to research in the literature if the generation and use of photovoltaic solar energy can contribute to the circular economy precepts. Searches were carried out in the ScienceDirect database using the words "solar and energy and circular economy", "photovoltaic and energy and circular economy" and 25 papers were found. The papers were classified under the themes "generation and use of photovoltaic solar energy"; "recovery of material from photovoltaic energy generation equipment" and "comparison with the generation of other forms of energy". Fifteen articles were found on "generation and use of photovoltaic solar energy", eight articles on "material recovery from photovoltaic energy generation equipment" and two articles on "comparison with the generation of other forms of energy". It was found in the research that photovoltaic solar energy, whether in the generation of energy considered a clean and renewable source, use or through its waste either from the production of equipment or after its useful life, is a technology that can contribute to the circular economy.
The report focuses on the mineral natural resources needed for digitalization. The use of digital applications and digital devices continues to grow and increasing amounts of information are being converted into a digital format. Prior research on digitalization in the context of sustainability has focused mainly on energy consumption and emissions. However, with the increasing demand for ICT hardware in numerous applications in modern society, the raw materials requirement of digital devices has become a crucial sustainability issue. Therefore, this report delves deeper into the topic of the raw materials consumption of digitalization. We focus on the following challenges and topics: • Sources, production, availability and sustainability of digitalization raw materials
• ICT sector's raw materials consumption, with a specific focus on selected key end-user devices: smartphones and smart TVs
• Key aspects of the ICT value chain
• Key ICT consumer and end-user aspects
• Possible solutions to support the sustainability of digital devices throughout their life cycle
• Key policy aspects and recommendations
Raportti käsittelee digitalisaatiossa tarvittavia mineraaliluonnonvaroja. Digitaalisten sovel-
lusten ja digitaalisten laitteiden käyttö lisääntyy jatkuvasti, ja yhä uutta tietoa muunnetaan
digitaaliseen muotoon. Aiempi tutkimus digitalisaatiosta vastuullisuuden näkökulmasta
on painottunut energiankulutukseen ja päästöihin. Koska ICT-laitteiden kysyntä useissa
nyky-yhteiskunnan käyttökohteissa kuitenkin kasvaa jatkuvasti, digitaalisten laitteiden
raaka-ainevaatimuksista on tullut vastuullisuuden kannalta ratkaiseva kysymys. Siksi tässä raportissa syvennytäänkin digitalisaation raaka-ainekulutukseen. Keskitymme seuraaviin haasteisiin ja aiheisiin:
• Digitalisaation raaka-aineiden lähteet, tuotanto, saatavuus ja vastuullisuus
• ICT-sektorin raaka-aineiden kulutus, painopisteenä valikoidut keskeiset loppukäyttäjä-
laitteet: älypuhelin ja älytelevisio
• Keskeiset näkökulmat ICT-alan arvoketjuun
• Keskeiset näkökulmat ICT-alan kuluttajiin ja loppukäyttäjiin
• Mahdolliset ratkaisut, joilla digitaalisten laitteiden vastuullisuutta voidaan tukea niiden
elinkaaren aikana
• Keskeiset poliittiset näkökulmat sekä suositukset
The present work presents a review of literature reviews in the area of recycling/reusing/re-manufacturing supply chain research. It also highlights the contribution of the review papers published in this area. To collect the sample, we use the well-reputed search engine: SCOPUS and then screening it categorically and descriptively to finalise the sample for the study. A category, impact, and topic-related classification schemes are developed, and the 67 review works existed in our final sample are discussed in the light of these classification schemes. Sustainability has three different facets: environmental, economic, and social. Achieving sustainability for enhancing the quality of the environment, cost-effective economic concern, and benefit of society is the priority in most of the articles. The study identifies several emerging issues like ways of utilisation of food and vegetable waste, ways of collection of rare earth metals from secondary sources, integration of reverse and forward supply chain, sustainable smart and flexible production system, etc., to give higher preferences for future research. The classification framework presented in this article may assist researchers to realise research gaps and help them in writing high-quality research work in the future.
This chapter introduces the concepts behind governance for an interdisciplinary audience of the relevant actors. We establish the definitions of governance used in this work and discuss governance from a technological context. We look at examples of the governance of sustainable technologies to date, with a particular focus on critical raw materials (CRMs). Further, the notion of research-oriented anticipative governance is introduced, along with the potential benefits of early stage intervention. Fuel cells are then presented as an upcoming technology where early stage governance could still have enormous benefit for preventing CRM-related bottlenecks in the future. We look at the tools that can be used according to our governance framework, especially including foresight, engagement, and integration.
The large generation of electronic waste (e-waste) is posing a serious threat to society. It is important to develop sustainable technology for the effective management of e-waste and the recovery of valuable metals from it. The present study employed hydrometallurgical approach for Cu and Ni extraction from waste printed circuit boards (WPCB) of mobile phones. This study demonstrates the application of ammonia-ammonium sulfate leaching for the maximum recovery of Cu and Ni. Investigations revealed that the most favourable reaction parameters for efficient metal extraction are - ammonia concentration - 90 g/L, ammonium sulfate concentration - 180 g/L, H2O2 concentration - 0.4 M, time - 4 h, liquid to solid ratio - 20 mL/g, temperature - 80 °C and agitation speed - 700 rpm. Under these conditions, 100% Cu and 90% Ni were extracted. Furthermore, the kinetic study was performed using the shrinking core model which revealed that the internal diffusion is the rate-controlling step for Cu and Ni extraction. The activation energies for Cu and Ni extraction were found out to be 4.5 and 5.7 kJ/mol, respectively. Finally, Cu was recovered with 98.38% purity using electrowinning at a constant DC voltage of 2.0 V at Al cathode. The present study provides a solution for concurrent extraction of Cu and Ni from the raw WPCB of mobile phones and selective recovery of Cu from metal leached solution. The process has the potential to recover the resources from WPCB while minimising the pollution caused by mismanagement of WPCB.
The emerging problem of electronic waste has promoted the interest in exploring metal recovery from secondary sources under the umbrella of urban mining. This study presents the physical and chemical characterization of various components present in end-of-life laptops to help ascertain the sites of metallic values and develop sustainable and environment-friendly recycling. The recycling potential of a laptop is evaluated by sequential disassembly, separation, and characterization of components such as body (49.8 wt.%), printed circuit board (9.7 wt.%), hard disk drive (4.9 wt.%), and battery (12.4 wt.%). The printed circuit boards comprise metallic values, majorly copper (25 wt.%), tin (5.8 wt.%), and lead (3.1 wt.%). The precious metals (Au, Ag) with an economic advantage are abundantly present in electronic components such as integrated circuits, capacitors, resistors, and processors. Critical elements such as lithium, cobalt, and rare earth elements are detected in the discarded laptops' batteries and hard disk drives. The recycling potential representing the amount of material that can be recycled in various components, depending on the type, concentration, and purity, is determined in the range of 36–100%. On average, a unit laptop contains~ 386 g of Cu (14.45 wt. %), 49.73 g Co (1.86 wt. %), ~346 mg Ag, ~141.2 mg Au, ~650 mg of rare earth elements (Nd, Dy). This study presents a database for investigating integrated and economical recycling techniques from different components of a laptop, and an overall process flow is also proposed.
Thermal treatment has been proved as an efficient and promising method for LCD panel scraps pre-treatment and resource recycling. However, undesirable pollutants including polycyclic aromatic hydrocarbons (PAHs) and heavy metals tend to occur during the thermal treatment. To better understand the metals migration behavior and to illustrate the interaction effect between organics and metals, effect of the polarizer on the metals (Cr, In, Ni, Cu, Zn, Fe) migration and transformation behaviors was analyzed in this study. Results showed that polarizer, the main organic component in LCD panel, could enhance the metals migration behavior during the thermal treatment and also affect the metals speciation distribution in solid residue. The enhancement effect on metals migration rate was mainly deduced by the gas/volatile compounds from polarizer decomposition, while the metals speciation distribution in solid residue was mainly affected by the solid product from polarizer decomposition. The polarizer also showed increase effect on the potential risk of In, Cu and decrease effect on Fe in solid residue. The results suggest that reducing the organics content or adding solid carbon in treatment system would helpful to decrease the metals migration during thermal treatment process of discarded LCD panels.
Using Aspergillus niger (A. niger) to produce low-concentration organic acids is challenging for dissolving In3O2 from waste LCD (liquid crystal display) panels with high toxicity. In this study, three bioleaching approaches from the general and the optimized fermentation systems were investigated respectively to compare indium recovery effects and firstly clarified its bioleaching mechanism. The indium bioleaching efficiency can be improved from 12.3% to 100% by fermentation method optimization. Carboxy groups from organic acids and proteins were the critical substances to release H⁺ for leaching indium mainly competed with iron via reactions analysis. The effective components increased after optimizing, including the dissociative H⁺ concentration, the effective carboxyl groups for leaching metal oxides, and the output of oxalic acid. A. niger biomass prevented the contact between H⁺ and In3O2 and adsorbed In³⁺ adverse to indium recovery. The bioleaching effects of fermentation broth for indium can be further promoted by controlling bioleaching process parameters.
Eco‐friendliness is becoming an indispensable feature for electrical and electronic equipment to thrive in the competitive market. This comprehensive review is the first to define eco‐friendly electronics in its multiple meanings: power saving devices, end‐of‐life impact attenuators, equipment whose manufacturing uses green processing, electronics that use materials that minimize environmental and health risks, designs that improve lifespan, reparability, etc. More specifically, this review discusses eco‐friendly technologies and materials that are being introduced to replace the well‐established ones. This is done for all material classes (metals, polymers, ceramics, and composites). Manufacturing, recycling, and final product characteristics are discussed in their various interconnected aspects. Additionally, the concept of consciously planned obsolescence is introduced to address the paradoxical relationship between durability and efficiency. The overall conclusions are that there is an important global trend to make electronics more eco‐friendly. However, matching the performance and stability of well‐established materials and technologies seems to be the main barrier to achieve it. These new implementations can have detrimental or beneficial net impacts on the environment. Assessing their net outcome is challenging because their impacts are frequently unknown and the current evaluation methods (and tools) are incapable of comprehensively quantifying these impacts and generating reliable verdicts.
With a huge amount of waste liquid crystal displays (LCDs) generated annually, their proper recycling raises continuous concern to realize pollution control (heavy metal and liquid crystal) and resource recovery (indium). However, due to their multi-metallic feature, traditional hydrometallurgy lacks of sufficient selectivity, which makes the recycling route lengthy, costly, and generate more waste. Electrodeposition acts as a prospective technique for selective metal extraction from multi-metallic system due to its high selectivity and electron as clean reagent. To fully develop its application in metal recovery, stepwise Cu/MoO2 and In electrodeposition from In-Cu-Mo-Fe waste LCD leachate is explored in depth. Electrochemical behavior analysis shows Cu and MoO2 can be first electrodeposited for their higher electroreduction potential. Cl⁻ acts as a key role in accelerating indium electroreduction process, which largely shortens the extraction time without the sacrifice of current efficiency. This accelerating effect was attributed to the increased number of electroactive species or collision frequency. Under optimized condition, 99.41% of indium (> 99% purity) can be electrodeposited within 13 h with high current efficiency. This study provides a cleaner approach for waste LCDs recycling and gives implications for the potential application of electrochemical technique in E-waste recycling.
For hydrometallurgical recovery of indium from glass cullet after dismantling a waste liquid crystal display (LCD), leaching is the rudimentary stage. Though size reduction of the cullet pieces adds convenience for recycling, from an efficiency and cost-effectiveness perspective regarding leaching process development, determining the proper cullet piece size is essential. Hence, in this study, leaching efficiency of indium as a function of cullet piece size was investigated, wherein the proper mechanical classification of crushed glass cullet could be addressed. The optimum conditions of 5 M mineral acid as the lixiviant, pulp density of 500 g/L, temperature of 75 °C, agitation speed of 500 rpm, 2 h process time were kept constant for the leaching studies. It was concluded that the size of the waste LCD cullet inversely affected the leaching efficiency of indium. For efficient leaching, a smaller cullet size is recommended; hence, waste LCD should be crushed to pieces 1 mm or smaller. Indium leaching behavior comparison using HCl, HNO3, H2SO4 revealed that all three mineral acids had similar leaching efficiencies. The reported process provides the missing link between physical dismantling and chemical processing for indium recovery via techno-economical-sustainable process development.
The management of Waste from Electrical and Electronic Equipment (WEEE) is always asking for innovative solutions. However, in order to make this business interesting for companies, more information is needed, especially economic data. To this aim, this work discusses the recycling of wasted Liquid Crystal Displays (LCDs), both in technical and economic terms. In addition, a sensitivity analysis has been implemented to justify the soundness of the results and the effect of instability on some critical variables. Results demonstrated as spent LCDs are an interesting field in which to develop circular practices. The economic analysis defines that the recycling of wasted LCDs are profitable in the baseline scenario (134 thousand €) and this is determined mainly by both back cover and valuable PCBs (Printed Circuit Boards). Additionally, the project is not economically feasible without a disposal fee (-1.7 million €).
Waste electrical and electronic equipment (WEEE) contains economically significant levels of precious, critical metals and rare earth elements, apart from base metals and other toxic compounds. Recycling and recovery of critical elements from WEEEs using a cost-effective technology are now one of the top priorities in metallurgy due to the rapid depletion of their natural resources. More than 150 publications on WEEE management , leaching and recovery of metals from WEEE were reviewed in this work, with special emphasize on the recent research (2015-2018). This paper summarizes the recent progress regarding various hydrometallurgical processes for the leaching of critical elements from WEEEs. Various methodolo-gies and techniques for critical elements selective recovery (using ionic liquids, solvent extraction, electrowinning, adsorp-tion, and precipitation) from the WEEEs leachates are discussed. Future prospects regarding the use of WEEEs as secondary resources for critical raw materials and its techno-economical and commercial beneficiaries are discussed.
On a global scale, the high consumption of electric and electronic equipment (EEE) leads to mounting volumes of e-waste. The e-waste problem in Egypt is not very well assessed, so a feasibility study for an e-waste dismantling facility in Cairo is introduced in this research. This feasibility study aims to provide a guide to set up an economically viable e-waste recycling business by calculating the main costs and revenues of the recycling system taking into account the environmental standards. The profit and loss predictions showed that the facility would gain revenues of USD 708,659 after a 5-year of operation.
The issue of E-waste disposal is concerning all the stakeholders, from policymakers to the end users which have accelerated the research and development on environmentally sound disposal of E-waste. The recovery of metals (gold, tantalum, copper, iron etc.) from E-waste has become an important focus. The mechanical recycling, thermo-chemical processes like pyrolysis, pyro-, hydro- and biometallurgical processes can play important roles in the Metal Recovery from E-waste (MREW) technology. For the industrial application of the MREW technology, it is important to analyze the sustainability. In this paper, two case studies have been presented on E-waste recycling industries in India and China. Based on the literature data, an attempt has been made to assess qualitatively the overall sustainability of MREW technology considering the three pillars, i.e., environmental, economic and social. Two conceptual frameworks with (Option-2) and without (Option-1) pyrolysis for integrated MREW units have been developed and the generalized energy and environmental impact analysis has been made using the principles of LCA. The impacts of two options have been compared. Option 2 has been found to be more efficient and sustainable. It has been realized that climate change, fossil fuel depletion, water depletion, eutrophication, acidification, fresh and marine water ecotoxicity are possible impact categories. The recommendations based on the generalized assessment are in good agreement with the findings of previous researchers on individual steps of MREW unit. The findings of this paper are expected to be beneficial to researchers and stakeholders for research directions and decision making on MREW. Open image in new window
This paper presents an experimentally-proved hydrometallurgical process for selective metals recovery from the waste-printed circuit boards (WPCBs) using a combination of conventional and time-saving methods: leaching, cementation, precipitation, reduction and electrowinning. According to the results obtained in the laboratory tests, 92.4% Cu, 98.5% Pb, 96.8% Ag and over 99% Au could be selectively leached and recovered using mineral acids: sulfuric, nitric and aqua regia. Problematic tin recovery was addressed with comprehensive theoretical and experimental work, so 55.4% of Sn could be recovered through the novel physical method, which consists of two-step phase separation. Based on the results, an integral hydrometallurgical route for selective base and precious metals recovery though consecutive steps, (i) Cu, (ii) Sn, (iii) Pb and Ag, and (iv) Au, was developed. The route was tested at scaled-up laboratory level, confirming feasibility of the process and efficiencies of metals recovery. According to the obtained results, the proposed hydrometallurgical route represents an innovative and promising method for selective metals recovery from WPCBs, particularly applicable in small scale hydrometallurgical environments, focused on medium and high grade WPCBs recycling.
Technology innovation has accelerated progress in Information and Communications Technology (ICT), especially in the mobile phones sector. Concurrently, local, national, and international governments are enforcing stricter regulations to protect natural resources and human health. The paper attempts to address the question: Have technological innovations and regulation development had a positive impact on ecosystems and public health? We identified 36 waste mobile phones (WMPs) manufactured between 2002 and 2013, assessed their metals concentration, leachability, and potential impact on environment and human health using digestion, Toxicity Characteristic Leaching Procedure (TCLP), and USEtox model, respectively. The results highlight that regulations did not have significant impact on total metal content, except some heavy metals, while technology innovation recorded stronger impact. WMPs should be classified as hazardous due to excessive lead content. Copper posed the most significant ecotoxicity risk, and chromium showed the most significant risk for both cancerous and non-cancerous diseases. Additionally, we demonstrated that WMPs toxicity increased with technology innovation.
This study proposed an innovative method to separate and recover indium and tin from spent indium–tin-oxide (ITO) targets. ITO was first dissolved using concentrated HCl and then the leaching solution was distilled to recycle HCl and crystallize indium and tin ions. Next, the obtained crystals were transferred into SOCl2 solution under refluxing to remove the crystal water. By simply fractionating the mixture, anhydrous indium chloride, tin tetrachloride, and SOCl2 can be separated in a single operation. The recovery rate of InCl3 was ca. 99.6% with a purity of ca. 99.8%, while ca. 98.0% of SnCl4 was recovered with a purity of ca. 99.7%. Both the recovery rates and purities are the highest reported so far. Since all the reagents used in this process were carefully designed, almost all of the reagents can be reused. This is an environmentally friendly, economical and practical method to efficiently recycle ITO targets.
ABSTRACT
The by-products of zinc refineries are used as the primary mineral resources for the commercial production of indium. The discarded LCDs containing adequate amount of indium is rather worth as its secondary resources compared to the by-products of zinc refineries. Mining and recycling rates of indium, respectively from minerals and waste LCDs are in progress to meet its huge demand. Recycling of the LCDs has been dominating over mining, as presently 480t of indium are produced annually from mining, however, that of 650t annually from recycling. Different aspects of the extractive metallurgy of indium are summarized in this review paper.
KEYWORDS: Indium, pyrometallurgy, hydrometallurgy, biometallurgy, recycling, recovery
https://www.tandfonline.com/eprint/hF4dWP3eMjyeq7trE9zV/full
Rapid Technological development induces increase of generation of used electric and electronic equipment waste, causing a serious threat to the environment. Waste printed circuit boards (WPCBs), as the main component of the waste, are significant source of base and precious metals especially copper and gold. Printed circuit boards (PCBs) are currently being dumped in landfills or incinerated which is causing a serious environmental harm in the form of toxic gases or leached hazardous compounds. To recover these metals from waste has always been a challenge. The paper here presents a detailed literature review on the components and the metal content of PCBs.
NdFeB permanent magnets have different life cycles, depending on the applications: from as short as 2–3 years in consumer electronics to 20–30 years in wind turbines. The size of the magnets ranges from less than 1 g in small consumer electronics to about 1 kg in electric vehicles (EVs) and hybrid and electric vehicles (HEVs), and can be as large as 1000–2000 kg in the generators of modern wind turbines. NdFeB permanent magnets contain about 31–32 wt% of rare-earth elements (REEs). Recycling of REEs contained in this type of magnets from the End-of-Life (EOL) products will play an important and complementary role in the total supply of REEs in the future. However, collection and recovery of the magnets from small consumer electronics imposes great social and technological challenges. This paper gives an overview of the sources of NdFeB permanent magnets related to their applications, followed by a summary of the various available technologies to recover the REEs from these magnets, including physical processing and separation, direct alloy production, and metallurgical extraction and recovery. At present, no commercial operation has been identified for recycling the EOL NdFeB permanent magnets and the recovery of the associated REE content. Most of the processing methods are still at various research and development stages. It is estimated that in the coming 10–15 years, the recycled REEs from EOL permanent magnets will play a significant role in the total REE supply in the magnet sector, provided that efficient technologies will be developed and implemented in practice.
The development of the recycling technologies for waste electrical and electronic equipment (WEEE) has entered a new stage. The WEEE disposing technologies have evolved from simple disassembly, classification and sorting to high value-added utilization technologies. In the past decade, some modified and novel technologies have been developed to recover metals from WEEE. This paper focuses on the recycling of metals from WEEE. The recycling principle, separating process, and optimized operating parameters of existing technologies are summarized and discussed in detail. Based on traditional recycling technologies of WEEE, pyrometallurgical technology and some mild extracting reagent, such as chloride medium, ammonia–ammonium and non-cyanide lixiviants can effectively recycle metals. Compared with the conventional acid and cyanide leaching, they have vast improvements in aspect of environmental protection. More than 98% of Cu and 70% of Au can be extracted. In addition, electrochemical technology, supercritical technology, vacuum metallurgical technology, etc. are also applied to recycle WEEE. The recovery rate of Cu and Pb under optimum conditions is around 84.2% and 89.4% respectively in supercritical water oxidation (SCWO) combined with electrokinetic (EK) technology. Vacuum technology has good environmental performance due to its avoiding discharge of waste water. Other new technologies such as ultrasound technology, mechanochemical technology, and molten salt oxidation technology have also been tried to recycle metals from WEEE. Regrettably, although many endeavors to develop recycling technologies have been attempted, these technologies are still relatively single and limited because WEEE is a complex system. Hence, the shortages and defects of each technology are discussed from the perspective of technological promotion and environmental protection. Furthermore, the outlook about the further development of recycling technologies for metals from WEEE is presented.
The etching waste solution from the indium-consuming fabrication processes is considered as the viable resource for indium recovery. The extraction equilibrium of indium(III) from a hydrochloride acid solution using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an extractant and dissolved in kerosene by solvent extraction was studied. To optimize the extraction and separation of indium from etching waste solution, the effects of O/A ratio, pH, and extractant concentration on the distribution ratios of In(III) and selective precipitation of alumina, cerium, and iron from indium were also investigated in this work. The experimental results showed that satisfactory separation of alumina, cerium, and iron from indium was achieved with 0.3 M D2EHPA at room temperature and pH values ranging from 1 to 1.5. In this process, 92% of indium could be extracted from 0.74 to 8.62 g/L at an O/A ratio of 1:1. Quantitative stripping experiments of indium by HCl showed that the preferred O/A phase ratio was 1:2 or less at HCl concentration of 2.0 M to attain a high indium recovery and minimum iron coextraction. Where maximum purity is desired, the extraction is desirably carried out in three theoretical extraction stages. Based on these results, the aqueous and organic phase parameters can be easily manipulated to attain a high separation efficiency of indium(III) from commonly associated elements. © 2016 American Institute of Chemical Engineers Environ Prog, 2016
Indium is a critical raw material with economic importance and high supply risk. In the present study, we recovered indium by means of cementation from a leaching solution of waste liquid crystal display panels. Cementation with zinc powder was optimized through the investigation of the effects of different variables (zinc concentration, pH, cementation time) on cementation efficiency and purity of the solid product. Almost all the indium present in the leaching solution passed to the solid phase when cementation was performed with a low (2–5 g/L), a medium (15–20 g/L) and a high (100 g/L) concentration of zinc, at pH 3. At pH 2, a complete cementation was obtained only with the highest concentration of zinc. Moreover, the highest purity of the indium product (62% indium percentage in the solid product, calculated in the 4-metal system indium-aluminum-calcium-iron) was achieved after a cementation of 10 min, whereas the presence of impurities increased with time. An empirical model successfully fitted the experimental data and suggested that the highest purity of the cemented product was expected at pH 2. A quantification of the environmental impact of the process for indium recovery from end-of-life liquid crystal display panels was also carried out through a life cycle analysis approach, and it outlined that relevant benefits to the environment were obtained thanks to the recovery of indium from waste electric and electronic equipment. The results obtained in the present study are promising since this is the first time that cementation was applied to a leaching solution of waste liquid crystal display panels. In this paper we found that indium cementation took place also with low concentrations of zinc at pH 3, allowing important reagent saving. Investigations in progress are aimed at increasing the purity of indium and at improving the environmental sustainability of the process. The approach presented here is considered extremely useful in the frame of urban mining strategies. It can help ensure progress towards sustainable societies, encourage industrial innovation of the recycling companies and the implementation of cleaner processes.
Background:
Electronic waste (e-waste) is produced in staggering quantities, estimated globally to be 41.8 million tonnes in 2014. Informal e-waste recycling is a source of much-needed income in many low- to middle-income countries. However, its handling and disposal in underdeveloped countries is often unsafe and leads to contaminated environments. Rudimentary and uncontrolled processing methods often result in substantial harmful chemical exposures among vulnerable populations, including women and children. E-waste hazards have not yet received the attention they deserve in research and public health agendas.
Objectives:
We provide an overview of the scale and health risks. We review international efforts concerned with environmental hazards, especially affecting children, as a preface to presenting next steps in addressing health issues stemming from the global e-waste problem.
Discussion:
The e-waste problem has been building for decades. The increasingly observed adverse health effects from e-waste sites calls for protecting human health and the environment from e-waste contamination. Even if e-waste exposure intervention and prevention efforts are implemented, legacy contamination will remain, necessitating increased awareness of e-waste as a major environmental health threat.
Conclusion:
Global, national, and local levels efforts must aim to create safe recycling operations that consider broad security issues for people who rely on e-waste processing for survival. Paramount to these efforts is reducing pregnant women and children's e-waste exposures to mitigate harmful health effects. With human environmental health in mind, novel dismantling methods and remediation technologies, and intervention practices are needed to protect communities.
With the liquid crystal displays (LCDs) being widely used in televisions, notebooks, and mobile phones, etc., large quantities of LCDs are entering into their end-of-life stage for treatment. If not treated properly, a loss of resources and undesirable impacts on the environment and human health can occur. In order to treat the waste LCDs in an efficient and environmentally friendly way, a combined process of physical methods was proposed to separate and recover materials from waste LCDs in the present study. On the basis of primary disassembly, two key processes (including liquid crystals removal and the recovery of polarizer and glass) were studied. Liquid crystals were removed from the panel glass by dissolving in isopropyl alcohol solution (16.7 vol.%) assisted with ultrasound. Recovery of polarizer and glass was achieved through mechanical crushing and gravity concentration. Results show that approximately 100 wt.% of liquid crystals were removed after dissolving for 45 min at 60oC. Up to 79.7 wt.% of polarizer was separated from glass and its average content in the recovered product was 90.3 wt.%.
Indium and other geologically scarce metals are routinely integrated into green technologies and modern consumer electronics. The manufacture of solar cells and liquid crystal displays (LCDs) relies strongly on continued indium supply, yet very little research has been conducted to determine what total resources exist to meet future or even present needs. This paper provides an improved understanding of the nature of indium resources and the current and future production and supply of this critical metal through a summary of global trends in indium production and demand, and through a preliminary account of global code-based reporting of indium mineral resources. Authors also present an overview of the potential for indium extraction from mine wastes and recycled electronics using Canadian and Australian case studies. Our preliminary data suggest that considerable resources are likely to exist in a diversity of deposits globally, which have the potential to meet long-term demand for indium. However, it is clear that a secured future supply of this metal will require some shift of focus from conventional extraction practices. It will be necessary to revisit controls on the conversion of resources to reserves and to supply and the discovery of additional resources to replace those depleted by continuing production. The prospects for indium supply from mine wastes and recycled electronics are found to be substantial, and these sources warrant greater consideration given their probable environmental and social advantages over the discovery and development of new primary indium deposits.
Indium is a critical element mainly produced as a by-product of zinc mining, and it is largely used in the production process of liquid crystal display (LCD) panels. End-of-life LCDs represent a possible source of indium in the field of urban mining. In the present paper, we apply, for the first time, cross-current leaching to mobilize indium from end-of-life LCD panels. We carried out a series of treatments to leach indium. The best leaching conditions for indium were 2M sulfuric acid at 80°C for 10min, which allowed us to completely mobilize indium. Taking into account the low content of indium in end-of-life LCDs, of about 100ppm, a single step of leaching is not cost-effective. We tested 6 steps of cross-current leaching: in the first step indium leaching was complete, whereas in the second step it was in the range of 85-90%, and with 6 steps it was about 50-55%. Indium concentration in the leachate was about 35mg/L after the first step of leaching, almost 2-fold at the second step and about 3-fold at the fifth step. Then, we hypothesized to scale up the process of cross-current leaching up to 10 steps, followed by cementation with zinc to recover indium. In this simulation, the process of indium recovery was advantageous from an economic and environmental point of view. Indeed, cross-current leaching allowed to concentrate indium, save reagents, and reduce the emission of CO2 (with 10 steps we assessed that the emission of about 90kg CO2-Eq. could be avoided) thanks to the recovery of indium. This new strategy represents a useful approach for secondary production of indium from waste LCD panels.
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With respect to a new pyrometallurgical process for the recoveries of metallic indium and tin from ITO (Indium Tin Oxide) scrap, laboratory scale experiments have been conducted to verify the proposed process for practical purpose. The process consists of two stages of reaction. At the first stage, ITO is reduced to In-Sn alloy with CO at a low temperature. At the second stage, indium in the In-Sn alloy preferentially vaporizes at a high temperature due to the difference between the vapor pressure of indium and that of tin. In the first stage of the process, 70 vol% CO, 1023 K and 90 min are desirable for reducing atmosphere, reduction temperature and reduction time, respectively, for the reduction of ITO with CO to In-Sn alloy. As for the second stage, the temperature more than 1373 K is required for rapid preferential vaporization of indium under vacuum.
Waste from end-of-life electrical and electronic equipment, known as e-waste, is a rapidly growing global problem. E-waste contains valuable materials that have an economic value when recycled. Unfortunately, the majority of e-waste is recycled in the unregulated informal sector and results in significant risk for toxic exposures to the recyclers, who are frequently women and children.Objectives
The aim of this study was to document the extent of the problems associated with inappropriate e-waste recycling practices.Methods
This was a narrative review that highlighted where e-waste is generated, where it is recycled, the range of adverse environmental exposures, the range of adverse health consequences, and the policy frameworks that are intended to protect vulnerable populations from inappropriate e-waste recycling practices.FindingsThe amount of e-waste being generated is increasing rapidly and is compounded by both illegal exportation and inappropriate donation of electronic equipment, especially computers, from developed to developing countries. As little as 25% of e-waste is recycled in formal recycling centers with adequate worker protection. The health consequences of both direct exposures during recycling and indirect exposures through environmental contamination are potentially severe but poorly studied. Policy frameworks aimed at protecting vulnerable populations exist but are not effectively applied.ConclusionsE-waste recycling is necessary but it should be conducted in a safe and standardized manor. The acceptable risk thresholds for hazardous, secondary e-waste substances should not be different for developing and developed countries. However, the acceptable thresholds should be different for children and adults given the physical differences and pronounced vulnerabilities of children. Improving occupational conditions for all e-waste workers and striving for the eradication of child labor is non-negotiable.
The recovery of ITO and the glass substrate from discarded TFT-LCDs, without crushing the glass substrate, was done by using an electrochemical method and acid treatments. Anodic conditions did not show any redox reaction of the ITO except oxygen evolutions. The oxygen evolution lifted the ITO layer off the glass substrate with remaining colour filer and black matrix. Recovery of the ITO was 75%, but it showed an In/Sn ratio of 15.9:1. The recovered ITO could not be suitable for reuse directly. Maybe, it needed an addition of extra Sn. However, this work presented a new process for the resource circulation of the indium from discarded LCD panels. The free glass substrate was then recovered after removing colour filter and black matrix by using an acid solution. The optical transmittance of recovered glass substrate was about 90% in the visible region, and the average roughness was 0.96 nm.
Electronic waste, which includes everything from refrigerators to smartphones, is one of the world’s fastest growing waste streams. Often these items are simply discarded as new technology becomes available. A huge amount of electronic waste is generated globally and currently only around 20% of it is recycled. The complex mixture of materials and components within electronic waste makes it difficult to manage and many of these components can pose hazards to human health or the environment if not disposed of carefully.
There have been significant changes in the global approach to electronic waste management and the legislation around it since the publication of the first edition of Electronic Waste Management. This new edition provides an updated overview across the world as well as presenting new chapters on current issues in recycling and management of this waste.
This is an essential reference not only for those working in recycling and waste management, but also for those working in manufacturing and product development who wish to consider the full lifecycle of their products. It also provides valuable insights for policymakers developing more environmentally sound and sustainable systems and strategies for the management of electronic waste.
Recycling of the waste LCD and recovery of indium which is an important classified critical raw material rarely have been industrially valorized for the circular economy due to lack of technology. Waste specific technology development is a cost-intensive and time-consuming process for the recycling industry. Hence, integrating existing technology for the purpose can address the e-waste issue in general and waste LCD in particular. Waste LCD and LCD industry itching wastewater are two important challenges can be addressed through an insightful combination of two. Hence, here possible integration of waste LCD leaching process with ITO wastewater treatment has been focused on indium recovery purpose. From our perspective process integration can be managed in two different ways, i.e., waste-to-waste mix stream process and integration of two different valorization processes for complete recovery of indium. With reference to indium recovery and context of e-waste recovery the process integration can be managed in two different ways, i.e., (i) waste LCD leaching with ITO etching industry wastewater then valorized (Waste-to-waste mix stream), (ii) Integration of waste LCD leaching process with ITO wastewater treatment process (integration of two valorization processes).Through proposed process semiconductor manufacturing industry and ITO recycling industry can address various issues like; (i) waste disposal, as well as indium recovery, (ii) brings back the material to production stream and address the circular economy, (ii) can be closed-loop process with industry and (iii) can be part of cradle-to-cradle technology management and lower the futuristic carbon economy, simultaneously.
With the increase of waste LCDs, indium recovery from waste LCD panels has aroused wide attention. In order to improve the indium recovery efficiency from waste LCDs, ultrasound was proposed to leach indium from waste LCDs in this study. With sulfuric acid as the leaching medium, influence of ultrasound and different factors on the indium leaching rate was investigated. Results show that the ultrasonic assistance can effectively improve indium leaching rate, and the leaching rate increases with the increase of ultrasonic power, reaction temperature and acid concentration, decreases with the particle size increasing. Under the optimized conditions i.e., ultrasound power of 800 W, reaction temperature of 60-70℃, sulfuric acid concentration of 0.5 mol/L, particle size smaller than 0.5 mm, 74.1% of indium was leached into the acid. Based on the results, reaction mechanism of ultrasonic assistance was further analyzed. According to the analysis, thermal and mechanical effect produced by sonochemical is the main reaction mechanism for the indium leaching reaction, which significantly improves the indium leaching rate.
This papers details a simple, sustainable approach for the recovery and concentrating of indium from waste scrap LCD panels. After manual dismantling, the glass fraction of the panel was pulverized through a mechanical treatment, Indium from crushed glass was then mobilized in an acidic solution such as HCl:HNO3 lixiviant followed by an ultrasonic wave. Indium was successfully adsorbed by three macro porous polystyrene-divinylbenzene resins (Lewatit TP 208, Lewatit TP 260 and Amberlite IRA 743) and the influence of pH, weight of resin, contact time, temperature and type of resin on the efficiency of sorption process were investigated and the optimum condition was found. Theoretical calculations, indicated the In(III) phase formed through the leaching process was InCl3(aq). The adsorbed In(III) onto the resins was effectively desorbed in acidic medium to prepare concentrated indium solution. For the kinetic study, the adsorption onto Lewatit TP 208, Lewatit TP 260 and Amberlite IRA 743 could be fitted to pseudo second-order.
More than three quarters of global indium consumption is used for the manufacture of liquid crystal displays (LCDs). These devices contain indium at concentrations that appear to be too low to be economically valorized by standard hydro- or pyrometallurgical methods under current market conditions. Because indium is a metal critical to many electronics and clean energy technologies, developing commercially viable processes for recovery indium from such end of life products is expected to offer societal benefit. While LCD screens contain indium at low levels, the surface confinement of indium in these devices makes abrasion an intriguing option for concentrating indium to industrially relevant levels. To that end, attrition scrubbing is investigated and shown capable of producing a concentrate upgraded in indium concentration by a factor of 10 with greater than 90% recovery of indium. The same process leaves the LCD glass cleaned of semiconductor elements that are viewed as impurities to the glass recycling sector. Relative economics of such a pretreatment process relative to direct chemical processing routes are presented.
The tremendous amount of end-of-life liquid crystal displays (LCDs) has become one of the prominent sources of waste electrical and electronic equipment (WEEE) in recent years. Despite the necessity of safe treatment, recycling indium is also a focus of waste LCD treatment because of the scarcity of indium. Based on the analyses of the structure of Indium Tin Oxide (ITO) glass, crushing is demonstrated to be not required. In the present research, a complete non-crushing leaching method was firstly adopted to recycle indium from waste LCDs, and the ultrasonic waves was applied in the leaching process. The results demonstrated that indium can be leached efficiently with even a low concentration of chloride acid (HCl) without extra heating. About 96.80% can be recovered in 60 mins, when the ITO glass was leached by 0.8 M HCl with an enhancement of 300 W ultrasonic waves. The indium leaching process is abridged free from crushing, and proves to be of higher efficiency. In addition, the ultrasonic wave influence on leaching process was also explained combing with micron-scale structure of ITO glass.
The present paper deals with physico-mechanical pre-treatments for dismantling of spent liquid crystal displays (LCDs) and further recovery of valuable fractions like plastic, glass and indium. After a wide experimental campaign, two processes were designed, tested and optimized. In the wet process, 20%, 15% and 40% by weight of the feeding panels are recovered as plastic, glass and indium concentrate, respectively. Instead, in the dry process, only two fractions were separated: around 11% and 85% by weight are recovered as plastic and glass/indium mixture. Indium, that concentrated in the -212μm fraction, was completely dissolved by sulphuric acid leaching (0.75molL(-1) H2SO4 solution, 80°C, 10%vol H2O2, pulp density 10%wt/vol, leaching time 3h). 100% of indium can be extracted from the pregnant solution with 5%wt/vol Amberlite™ resin, at room temperature and pH 3 in 24h. Indium was thus re-extracted from the resin by means of a 2molL(-1) H2SO4 solution, at room temperature and S/L of 40%wt/vol.
Considering indium scarcity, the end-of-life (EOL) LCD, which accounts for up to 90% of market share can be a feasible secondary resource upon successful recycling. In the preferred hydrometallurgical process of such critical metals, leaching is the essential primary and essential phase has been investigated. In this process, LCD was mechanically separated along with other parts from EOL TVs through a smartly engineered process developed at our institute, Institute for Advanced Engineering (IAE), the Republic of Korea. After removing plastics and metals from the LCD, it was mechanically shredded for size reduction. The mechanically shredded LCD waste was leached with HCl for recovery of indium. Possible leaching parameters such as; effect of acid concentration, pulp density, temperature and effect of oxidant H2O2 concentration were investigated to identify the best conditions for indium extraction. Indium (76.16 × 10−3 g/L) and tin (10.24 × 10−3 g/L) leaching was achieved at their optimum condition, i.e. lixiviant of 5 M HCl, a pulp density of 500 g/L, temperature 75 °C, agitation speed of 400 rpm and time for 120 min. At optimum condition the glass, plastic and the valuable metal indium have completely been separated. From indium enriched leach liquor, indium can be purified and recovered through hydrometallurgy.