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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.

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... 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]. ...
Article
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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.
... 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). ...
Preprint
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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 above being a consequence of its special properties and wide industrial uses, i,e., liquid-crystal displays (LCDs), electronics, catalysts, etc. Thus, the recovery of this element from the above sources is an important target, and several technologies had been proposed to resolve such a situation [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13]. Besides the above, indium is considered a hazardous element due to its carcinogenic character [14], being its removal from residual aqueous solutions i.e., resulted from a number of the above processes, is of the foremost importance, and here it is when liquid membranes must be considered as a technology suitable for the recovery of metals or other solutes present, in the few mg/L concentration order, in the wastewaters. ...
... This expression combines the diffusional and equilibrium parameters involved in the transport of indium(II), from HCl solutions, across a membrane supporting the ionic liquid. Then: (8) and Db,org being of 5.6x10 -2 cm 2 /s. It can be observed, that Dorg had a lower value than Db,org, the reason may be caused to the diffusional resistance due to the membrane thickness located between the source and receiving phases. ...
Preprint
The transport of indium(III), from HCl solutions, across a supported liquid membrane in flat-sheet configuration was investigated, being the carrier the ionic liquid HA324H+Cl- (derived from the tertiary amine Hostarex A324 and hydrochloric acid). Different variables affecting the metal transport: hydrodynamic conditions in the source and receiving phases, metal and HCl concentrations in the source phase, and carrier concentration in the membrane phase, were investigated. Also the transport of indium(III) using carriers of various nature: ionic liquids, alcohol, ketone, phosphine oxide, etc., was compared. The metal transport was modelled describing the transport mechanism as: diffusion across the source diffusion layer, a fast interfacial chemical reaction, and diffusion of the InCl4--carrier complex through the membrane support. Diffusional parameters for the transport of indium(III), from the experimental data and the model, were estimated.
... The simple design process allows an indium recovery efficiency higher than 90% and makes it suitable for fulfilling an entire management system for the enhancement of LCDs [45]. Considering the strategic role of indium, recycling further fractions (e.g., plastic, printed circuit boards) could have a significant impact from an economic point of view [14,45,46]. Compared to the current literature, the treatment solves one of the main panel recycling bottle-necks due to the relatively low indium concentration. ...
Article
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End-of-life liquid crystal displays (LCD) represent a possible source of secondary raw materials, mainly glass and an optoelectronic film composed of indium (90%) and tin (10%) oxides. A strong interest for indium, classified as critical raw material, pushed research towards the development of high-efficiency recycling processes. Nevertheless, a deepened study of the technological innovation highlighted that only a small number of treatments included use of whole waste. Furthermore, these processes often need high temperatures, long times, and raw materials that have a significant environmental impact. In this context, this article shows an approach developed in accordance with the “zero waste” principles for whole, end-of-life LCD panel recycling. This process includes preliminary grinding, followed by cross-current acid leaching and indium recovery by zinc cementation, with efficiencies greater than 90%. A recirculation system further increases sustainability of the process. To enhance all waste fractions, glass cullets from leaching are used for concrete production, avoiding their disposal in landfill sites. Considering the achieved efficiencies, combined the simple design suitable for real-scale application (as confirmed by the related patent pending), this process represents an excellent example of implementing circular economy pillars.
... • 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). ...
Article
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.
... 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]. ...
Article
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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.
... 7 ITO is principally used as a transparent, conductive thin-film coating on displays (most commonly LCDs), and the indium content in waste LCD is considered to be about 100 ppm. 8 In particular, the ITO used in the panel is mainly composed of 90 wt.% In 2 O 3 and 10 wt.% SnO 2 . ...
Article
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Using ammonium chloride as chlorination agent, indium in waste liquid crystal display panels was successfully extracted by microwave-assisted chloride metallurgy under vacuum pressure. Optimal conditions for indium extraction from pure indium oxide are explored through single factor and orthogonal experiments, and the indium extraction ratio was 98.91 % when temperature was 500 Cl/In molar ratio was 8, and heating time was 3 min for pure In2O3. The Cl/In molar ratio illustrates the most important effect on indium extraction, followed by heating temperature and heating time. For the extraction of indium in the waste liquid crystal display panel powders (-indium extraction ratio was nearly 79.46 % for waste liquid crystal display panels under the condition that the ammonium chloride mass ratio was 0.6 wt%, temperature was 500 min. Excess gaseous hydrogen chloride would react with ammonia to form ammonium chloride during the condensation, which avoided the emission of hydrogen chloride into the environment. This work presented a promising technology for the extraction of indium from waste liquid crystal display panels with a very low heating time and a relatively low chlorination agent loss, and no harmful gas emission.
... 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]. ...
Article
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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.
... However, there is growing concern in the Spanish cement industry about the progressive decrease in the availability pozzolans traditionally listed in the European standard. In this context, the need to diversify the sources of mineral additions with pozzolanic activity for use in cement manufacture and derived materials is highlighted [4][5][6]. ...
Article
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The processes focused on stone cutting generate a large volume of waste. Small size waste, silt/clay, is not used and goes to landfill. However, the composition of these wastes makes them useful for adding to cements and for use in construction. In the present paper, 10% Ordinary Portland cement is replaced by 10% waste from granite sawmill, which is studied to obtain sustainable ecological cement. This replacement provides advantages from the morphological and chemical point of view at the cements. The waste has a particle size that does not exceed 15 µm and that when replacing in the cement, after the hydration reaction, generates structures where Calcium Silicate Hydrate (C-S-H) gels and double layered hydroxide compounds (LDH) are reaction products formed in high concentration. These products develop stable phases in the structures over long time periods such one year, which was the time frame used in this study.
... Simply put, it allows data obtained from the sensors to be easily understood by the users [27]. It is one of the two graphical user interfaces implemented [28,29]. ...
Article
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The use of fireworks and firecrackers to celebrate festivities is a very common activity in the Philippines. But due to the lack of strict control and regulation, there are unwanted risks of accidents from occurring due to the poor handling and storage conditions of these devices. Proper monitoring is important to reduce any unnecessary risks imposed on human life and property. While existing storage monitoring devices exist, the developed prototype is designed to contain sensors that are more suited in monitoring the ideal conditions of where the fireworks are stored. Monitoring the climate conditions on these devices may seem trivial at first, but such climate change can involve a rapid rise in temperature that can accidentally ignite the fireworks and deal with catastrophic damage. Another concern is the rise of humidity that may alter that chemical characteristics of the gunpowder stored in the fireworks. Such changes may not have any noticeable effects until it arrives in the consumer, that may experience an unwanted and unintended change in the performance of the fireworks leading to accidents. Therefore, it is important for this device to properly monitor the surrounding area then indicate various forms of alarms as a method of redundancy.
... Currently, the concept of "urban mining" is increasingly used in relation to entities recovering particular materials from waste (e.g. "mining"): Akcil, Agcasulu & Swain, 2019;Arora, 2020). The adjustment actions of the technological process itself in the scope of the introduction of circular economy in mining plants will have to be of a varied nature, tailored to the specificity of each plant. ...
Article
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The publication analyses and evaluates the impact of the implementation of circular economy on the economy and especially on its mining and power generation sector in Poland. Circular economy is a relatively new concept concerning an innovative economic development model. The publication briefly describes the concept of circular economy. Among other things, the basic economic processes that make up circular economy are discussed. In addition, history is presented as well as examples of legislation that have had the strongest impact on the implementation of circular economy in the EU are identified. Further on in the paper, the impact that circular economy will have on the mining and power generation industry in Poland is discussed. Areas have been identified that will need the most attention in relation to the implementation of circular economy. It was pointed out that in the mining and power generation sector the scale of use of current and landfill waste should be increased as a priority. Attention has been paid to the necessary reduction of water demand and rational water and sewage management. Examples of use of mining gas and ventilation air have been discussed. The publication provides examples of a number of measures taken in accordance with circular economy. It was pointed out that there is still a need to popularize the existing ones and to look for new technical and organizational solutions conducive to the introduction of this new economic model. An important aspect of the impact of the circular economy on these sectors will be the decrease in energy demand resulting from the widespread implementation of the new economic model. For those already struggling with a number of problems of some of the mining and power generation sectors based on coal mining and combustion in Poland, the implementation of circular economy will pose another challenge.
... 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]. ...
Article
Full-text available
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 above is a consequence of its special properties and wide range of industrial applications, i.e., liquid-crystal displays (LCDs), electronics, catalysts, etc. Thus, the recovery of this element from the above sources is an important target, and several technologies have been proposed to resolve this issue [1][2][3][4][5] , including ion-exchange 6 , adsorption 7 , cementation 8 , liquid-liquid extraction [9][10][11] , liquid membranes 12 and a process that uses a sequence of steps: leaching-distillation-refluxing in SOCl 2 13 . Moreover, the use of bioleaching with A. thiooxidans and A. ferrooxidans has been proposed in the treatment of LCD panels 14,15 ; however, it is assumed that bioleaching processing has a higher environmental impact than some chemical processes due to its long duration and high electricity consumption 16 . ...
Article
Full-text available
By reaction of HCl and the tertiary amine HA324, an ionic liquid denoted HA324H+Cl− was generated and used in the transport of indium(III) from HCl solutions. Metal transport experiments were carried out with a supported liquid membrane, and several variables affecting the permeation of indium(III) across the membrane were tested: stirring speed, metal and acid concentrations in the feed solutions and the carrier concentration in the supported organic solution. The metal transport results were also compared with those obtained using different carriers in the solid support. A model that described indium(III) transport across the membrane was proposed, and the corresponding diffusional parameters were estimated.
... As most of the globally produced In being used in optical display devices, the industrial-scale In recovery from EOL e-wastes like LCD, and LED are a challenge for the circular economy notion of this metal. As reported in the literature, after leaching the In content in leach liquor is very small for industrial recovery, which is a genuine challenge and adversely affects the In recovery interests from these resources [12,14,15]. Indium and Sn recovery from ITO bearing EOL waste LCD and its optimization process has already been developed in our earlier research and reported elsewhere [12,15]. ...
Chapter
Various e-wastesE-waste like waste LCD, LED, and LCD etching industry wastewaterWastewater are important secondary resourcesSecondary resourcesfor indiumIndium, which is a critical metal. In this research, the industrial-scale indiumIndiumrecoveryRecoveryfrom e-wasteE-waste resources like waste LCD, LED, and LCD industry etching wastewaterWastewater is being emphasized through simulation and integration of the developed processes. A demonstration plant for indiumIndiumrecoveryRecovery on one ton/day of ITO etchingITO etchingwastewaterWastewater has been developed with almost complete (99%) recoveryRecoveryof indiumIndium. For the indiumIndiumrecoveryRecovery, integration of the processes can be managed by following two approaches unique to this system, (i) utilization of ITO etchingITO etchingindustry wastewatersWastewater for the leachingLeaching of waste LCD, (ii) integration of leachingLeaching processes developed for waste LCD and LED with that of the treatment process for ITO wastewatersWastewater. Through the proposed approach, the semiconductor manufacturing industry and ITO industry can address various pressing issues like (i) waste disposal, (ii) indiumIndiumrecoveryRecovery, (iii) circular economyCircular economy.
... Within this model, it is planned to reduce the negative environmental impact of cities by 2030, paying special attention to the management and recycling of generated waste [3]. Sustainable cities are thus required to achieve, through technological innovation, substitution of the "linear economy" for a "circular economy", in which waste is incorporated (again and again) in the production processes of new products and/or materials (towards the "zero-waste" objective) [4]. ...
Article
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This article demonstrates the possibility of producing alkali-activated materials (AAM) from a mixture of mechanically processed concrete, ceramic, masonry, and mortar wastes, as a sustainable alternative for recycling construction and demolition wastes (CDWs) under real conditions. The addition of 10% Portland cement allowed the materials to cure at room temperature (25 °C). CDW binder achieved a compressive strength of up to 43.9 MPa and it was classified as a general use and low heat of hydration cement according to ASTM C1157. The concrete produced with this cement and the crushed aggregates also from CDW reported a compressive strength of 33.9 MPa at 28 days of curing and it was possible to produce a high-class structural block with 26.1 MPa according to ASTM C90. These results are considered one option in making full use of CDWs as binder and aggregates, using alkaline activation technology thereby meeting the zero-waste objective within the concept of the circular economy.
... 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]. ...
Article
Full-text available
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.
... 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. ...
Article
(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.
... 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. ...
Article
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.
... 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]. ...
... The co-valorization of different waste streams is in line with the principles of industrial symbiosis and circular economy [30,31]. Thus, this research study aims to fully investigate the optimum alkali-activation synthesis conditions and the associated properties of IPs produced using brick wastes and metallurgical slag as raw materials. ...
Article
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This paper explores the alkali activation potential of brick wastes and metallurgical slags. Inorganic polymers (IPs) were produced using an alkaline medium consisting of sodium hydroxide and sodium silicate solutions and the optimum synthesis conditions were determined. In this context, the variable parameters, such as solid to liquid (S/L) ratio, curing temperature (60, 80 and 90 °C) and ageing time (7 and 28 days) on the compressive strength and the morphology of the produced IPs were investigated. Specimens produced under the optimum synthesis conditions were subjected to high temperature firing and immersed in distilled water and acidic solutions for various periods of time, in order to assess their durability and structural integrity. The results showed that the IPs produced using a mix ratio of 50 wt % metallurgical slag and 50 wt % brick wastes, cured at 90 °C and aged for 7 days obtained the highest compressive strength (48.9 MPa). X-ray fluorescence analysis (XRF), particle size analysis, Fourier transform infrared spectroscopy (FTIR), mineralogical analysis (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and thermogravimetric (TG) analysis also confirmed the optimum microstructural characteristics and the chemical reactions that took place during synthesis. The overall results of this study indicate that the co-valorization of different waste streams, which are produced in large quantities and cause environmental problems if not properly managed, is a viable alternative for the production of binders or secondary construction materials with higher added value.
Article
A large amount of waste liquid crystal display (LCD) glass becomes a secondary waste after extracting the scarce metal indium from waste LCD by acid leaching. The feasibility of preparing biocarriers from waste LCD glass as raw materials was studied. The effects of different types and contents of foaming agents, foaming temperature and time on the biocarriers were studied. Under the condition of foaming temperature of 1050 ℃ and foaming time of 20 min, a suitable biocarrier was prepared by adding 5% CaCO3 as a foaming agent into the waste LCD glass (denoted as Biocarrier-CaCO3). The technical indicators, which including void fraction, specific surface area, compressive strength and others of the Biocarrier-CaCO3, met the standard of CJ/T 299-2008 for water treatment. When Biocarrier-CaCO3 was applied for Shewanella cultivating, the biomass of the biofilm reached as high as 38 mg/g. In contrast, Na2CO3 was not suitable for the preparation of biocarriers for its porcelainization; SiC also failed as a foaming agent because the strength of the biocarrier could not reach the technical requirements of the product. In all, this study provided a novel strategy to recycle waste LCD glass as biocarrier to support the development of microbes and biofilm.
Article
The increasing demand for metals and the concomitant depletion of the primary metallic resources is one of the most important environmental and societal challenges nowadays. Critical metals, rare earth elements, base and precious metals demand is growing day-by-day and driving many metals towards the edge of supply risk. On the other hand, the problems linked to waste generation (especially waste electrical and electronic equipment (WEEE)) are also increasing globally. These end-of-life electronic wastes contain significant concentration of critical raw materials accompanied by harmful substances. Spent Li ion batteries is a kind of WEEE stream, bearing considerable concentrations of valuable metals (like Co, Li, Mn and Ni). If the end-of-life Li ion batteries are not managed properly, there is a high risk that these valuable metals and toxic substances could end into the environment. In order to address the environmental complications, sustainable resource management and boost circular economy, it is important to properly manage and recycle these spent Li ionbatteries. Conventional methods based on high-temperature pyro-metallurgical routes together with hydro-metallurgical processing have been widely studied for the recovery of metals from spent LiBs. However, bio-metallurgical approaches have an edge over their counter parts because of their environmentally friendly nature. Microbe-metal interactions have received special attention both in terms of leaching metals from WEEE and also in recovering metal ions from aqueous streams. Microbial technologies are promising for removing metal ions because of less cost, technical feasibility for large scale applications and no need for addition of toxic chemicals thereby avoiding generation of toxic or hazardous byproducts. In this study, particular emphasis is placed on reviewing the progress made in biohydrometallurgy (i.e. bacterial and fungal leaching practices as one and two-step mode) for the leaching of critical metals from waste lithium ion batteries. Biotechnological methods (e.g. biosorption, bioprecipitation and bioelectrochemical treatment) for the recovery of critical metals from pregnant leachates and aqueous streams are also discussed.
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Since the ratification of the Kyoto protocol by the EU in 2002, Members States have committed themselves both to reducing their greenhouse gas emissions and to environmental sustainability, inter allia by using cements with alternative additions that incorporate industrial waste. In this paper, ionic mobility through a pozzolanic cement is studied. The cement contains substitutions of 10% and 20% rejected ballast waste and is prepared for railway infrastructure (slab or ballast less track) that is exposed to extreme climatic conditions (high thermal amplitudes and saline environments). Studied with CT-Scanning, ionic mobility can be observed along the cement pores. The cement with 10% substitutions of ballast waste was considered ideal to minimize ionic penetration and cement deterioration.
Article
The phenomenon of the long leaching time and low leaching rate is presented in the acid leaching process under the conventional conditions of low reaction temperature and acid concentration. In order to promote leaching rates of indium and tin in waste liquid crystal display, an optimized process combining rapid milling and acid leaching has been proposed, which is more time and energy-efficient, environmentally sound compared with the traditional acid leaching process. Leaching mechanism analysis was conducted to uncover the different leaching behavior of indium and tin. And the external factors affecting the leaching rates of indium and tin were studied to optimize. In this process, the fine powder with a weight ratio of 97.6%, which particle size less than 0.075 mm, was obtained with the optimal milling time of 30 min by rapid grinding in the planetary high energy ball milling. About −0.003 l/s of grinding rate constant was performed in the grinding size fraction from 3 mm to 0.075 mm. The research results indicated that the particle size less than 0.035 mm was agglomerated, and the addition of H2O2 reduced the leaching rate for the particle size less than 0.075 mm. Moreover, 86.3% and 76.1% of indium and tin were leached in a short leaching time of 10 min by using 3 M H2SO4 at 85 °C for particle size range from 0.075 to 0.035 mm, while 96.9% and 85.6%, respectively in 90 min.
Article
Thermal decomposition was used to enrich indium tin oxide (ITO) from waste colour filter glass. The colour layer was destroyed through oxidation, and the ITO layer was separated from the glass substrate. With the increase in the temperature and time of thermal decomposition, the yield of ITO concentrate decreased, but the ITO recovery and enrichment ratio increased. Furthermore, the ITO could be effectively enriched at 600 °C and 8 min, where the yield, recovery and enrichment ratio of ITO were 0.06%, 98% and 1669, respectively. The particle size distribution of the ITO concentrate was mainly distributed in 0.1–1.3 and 2.6–42.0 μm, with cumulative percentages of 4.33% and 95.55%, respectively. Moreover, the crystal structure of recycled ITO was not changed. Substantial poisonous and harmful mixed flue gas are produced during thermal decomposition. After condensation and adsorption by activated carbon, the emission of mixed flue gas could be effectively controlled to avoid serious pollution to the atmospheric environment.
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In the extant literature, circular economy (CE) is considered a driver for sustainable development of the manufacturing sector, being it an industrial paradigm aiming at regenerating resources. CE is transferred to manufacturing companies through the adoption of different Circular Manufacturing (CM) strategies (e.g., recycling, remanufacturing, etc.). Nowadays, manufacturers are struggling to implement these strategies to limit their resource consumption and pollution generation. To enable their adoption, the extant literature unveiled the importance to control along the entire value chain different types of resource flows (i.e., material, energy, and information). Nevertheless, while for material and energy management some advancements were achieved, information management and sharing remains one of the major barriers in adopting these strategies. The present work, through a systematic literature review, aims to identify the relevant information and data required to support the manufacturer’s decision process in adopting and managing the different CM strategies to pursue the transition towards CM. Furthermore, based on the results obtained, this research proposes a theoretical framework. It elucidates the four main areas to be managed by manufacturers in adopting CM strategies and it provides to the manufacturer an overview of what should be updated and upgraded inside the company to embrace CM strategies.
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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.
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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.
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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.
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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.
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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.
Article
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.
Chapter
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.
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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.
Technical Report
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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
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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
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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.
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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.
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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.
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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.
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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 €).
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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.
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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.
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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
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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
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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.
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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.
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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.%.
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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.
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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. Copyright © 2015 Elsevier Ltd. All rights reserved.
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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.
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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.
Chapter
Since the last decade there have been many changes to legislation impacting the manufacture of electrical and electronic equipment (EEE), proscribing a wider range of input materials. The cases of lead, cadmium, mercury, hexavalent chromium and brominated flame retardants in particular are examined. Product innovations have increasingly been made possible owing to the application of novel materials containing elements that are sometimes rare, expensive and in limited supply, so-called critical raw materials. This chapter discusses the issues surrounding the use of gallium, cobalt, tantalum, indium, antimony and silicon in EEE and in batteries. Along with the common thermoplastics, opportunities for closed loop or in-sector recycling exist but are currently not adequately exploited. The strengthening of key European Union Directives has required industry to adopt a more holistic approach to manufacture, with the emphasis being placed on all aspects of a product's lifecycle, from design to the end-of-life, with legislation and the economics of materials supply and lifecycle management being the key drivers for change. Applying ecodesign principles, which include materials selection, will lead to further integration of environmental considerations during the design and materials selection phases of a product. This will require changes in thinking and practice within the electronic and recycling industries which will address the waste electrical and electronic equipment (WEEE) challenge.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
Article
As one of the most widely used scarce metals located at the column of IIIA in the periodic table, indium has drawn more and more attention due to its semiconductor and optoelectronic performance. While the reduction of indium minerals, as one of secondary resources, the amount of waste liquid crystal display (LCD) has been accumulated considerably. Indium tin oxide (ITO) film which is the main functional fraction of LCD has consumed more than 70% of the indium production worldwide. Therefore, it is necessary to recycle indium from waste LCDs. Some researches have been done for proper treatment to recycle indium from waste LCD which is a primary part of waste electric and electronic equipment (WEEE). In this paper, the main characteristics of indium and the waste management status of end-of-life LCDs are introduced. And we mainly focus on the highly developed single recycling and reusing techniques. In addition, several combined recycling processes are evaluated. Furthermore, on the foundation of techniques and processes mentioned above, the promising related single techniques and the improvements on whole treatment process of waste LCDs are suggested.
Article
Abstract: A laboratory scale sustainable commercial green process for treatment of indium-tin-oxide (ITO) etching wastewater and total recovery of In, Mo, Sn and Cu by combination liquid-liquid extraction and wet chemical reduction has been developed. The ITO etching wastewater is a threat to the ecosystem and human health, containing significant amounts of valuable metals like In and Cu. In metal and 100nm Cu nanopowder with 5N purity has been recovered. The developed process concurrently treats the ITO etching wastewater and recovers pure metals. By the process, Mo and Sn are recovered by liquid-liquid extraction, In is recovered through liquid-liquid extraction followed by wet chemical reduction. Value added semiconductor industry grade Cu nanopowder is recovered through wet chemical reduction using ascorbic acid. After a series of treatment, the wastewater is free of pollutant, worthy to use in the same industry or disposed. The process is a sustainable, green, versatile and flexible process.
Article
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.
Article
Chalcopyrite is the primary copper mineral used for production of copper metal. Today, as a result of rapid industrialization, there has been enormous demand to profitably process the low grade chalcopyrite and "dirty" concentrates through bioleaching. In the current scenario, heap bioleaching is the most advanced and preferred eco-friendly technology for processing of low grade, uneconomic/difficult-to-enrich ores for copper extraction. This paper reviews the current status of chalcopyrite bioleaching. Advanced information with the attempts made for understanding the diversity of bioleaching microorganisms; role of OMICs based research for future applications to industrial sectors and chemical/microbial aspects of chalcopyrite bioleaching is discussed. Additionally, the current progress made to overcome the problems of passivation as seen in chalcopyrite bioleaching systems have been conversed. Furthermore, advances in the designing of heap bioleaching plant along with microbial and environmental factors of importance have been reviewed with conclusions into the future prospects of chalcopyrite bioleaching. Copyright © 2015 Elsevier Ltd. All rights reserved.
Article
In the present work the recovery of indium and of the polarizing film from waste liquid crystal displays was experimentally investigated in the laboratory. First of all, the polarizing film was removed by employing a number of different techniques, including thermal and chemical treatments. Leaching of indium was then performed with HCl 6N, which allowed solubilisation of approximately 90% In (i.e. 260mg In per kg of glass) at room temperature, without shredding. Indium recovery from the aqueous phase was then investigated through solvent extraction with polyethylene glycol (PEG)-based aqueous biphasic systems. Indium extraction tests through the PEG-ammonium sulphate-water system were conducted as a function of PEG concentration, salt concentration and molecular weight of PEG, using 1,10 phenanthroline as a ligand. The experimental results demonstrated that indium partitioning between the bottom (salt-rich) and the top (PEG-rich) phase is quite independent on the composition of the system, since 80-95% indium is extracted in the bottom phase and 5-20% in the top phase; it was also found that when PEG concentration is increased, the ratio between the bottom and the upper phase volumes decreases, resulting in an increase of indium concentration in the bottom phase (at [PEG]=25% w/w, indium concentration in the bottom phase is ∼30% higher than the initial concentration before the extraction). Copyright © 2015 Elsevier Ltd. All rights reserved.
Article
Although copper is the principal metal in most electronic scrap, printed circuit boards in mobile phones also contain a significant amount of silver, gold and palladium. A bench-scale extraction study was carried out on the applicability of economically feasible hydrometallurgical processing routes to recover these precious metals. The starting material contained 27.37% copper, 0.52% silver, 0.06% gold and 0.04% palladium. In a first step, the following leaching solutions were applied: An oxidative sulfuric acid leach to dissolve copper and part of the silver; an oxidative chloride leach to dissolve palladium and copper; and cyanidation to recover the gold, silver, palladium and a small amount of the copper. A thiourea leach, as an alternative to cyanidation, was also investigated but did not give a sufficiently high yield. To recover the metals from each leaching solution, the following methods were evaluated: cementation, precipitation, liquid/solid ion exchange and adsorption on activated carbon. Precipitation with NaCl was preferred to recuperate silver from the sulfate medium; palladium was extracted from the chloride solution by cementation on aluminum; and gold, silver and palladium were recovered from the cyanide solution by adsorption on activated carbon. The optimized flowsheet permited the recovery of 93% of the silver, 95% of the gold and 99% of the palladium.
Chapter
Environmental problem turns one of the most important issue in the world. Recently, more and more people concerned about environment and their health. Especially, waste management and resources recycling issues are important problems equal to global warming, disruption of ecosystem and other problems. The markets of electric appliances and electronics devices are highly developing, therefore wastes from those items are supposed to be rapidly increasing. Rapid rise of industrial production leads to growing demand of resources, so securing of resources is very important for manufacturer in the future. So there are strong needs to recover and recycling of resources from used products and waste from materials. Thanks for its advantages such as “flat screen”, “lightweight”, and “low power consumption”, LCD panels are utilized in many final products such as LCD TV, mobile phone etc. And the production of final products with LCD are growing rapidly, too. Therefore, in the recycling technology of LCD panels, we should focus on how we collect the materials from LCD panel effectively. Especially, indium is very important. Because indium is a one of rare metal, and essential materials for transparent electrode of LCD panel. To avoid the shortages of indium for LCD production in near future, securing indium resources is important for LCD panel manufacturers. We are developing technologies that work to recover indium resources from LCD panels. In particular, the simple and energy-saving ion exchange method is proving to be effective approach. We have constructed demonstration equipment that can process 240kg of waste LCD panels per day. We have achieved a recovery rate of 94%, using glasses discarded from LCD panel manufacturing plant.
Article
A few studies have focused on release of valuable/toxic metals from Pb/Zn smelting slag by heterotrophic bioleaching using expensive yeast extract as an energy source. The high leaching cost greatly limits the practical potential of the method. In this work, autotrophic bioleaching using cheap sulfur or/and pyrite as energy matter was firstly applied to tackle the smelting slag and the bioleaching mechanisms were explained. The results indicated autotrophic bioleaching can solubilize valuable/toxic metals from slag, yielding maximum extraction efficiencies of 90% for Zn, 86% for Cd and 71% for In, although the extraction efficiencies of Pb, As and Ag were poor. The bioleaching performance of Zn, Cd and Pb was independent of leaching system, and leaching mechanism was acid dissolution. A maximum efficiency of 25% for As was achieved by acid dissolution in sulfursulfur oxidizing bacteria (S-SOB), but the formation of FeAsO4 reduced extraction efficiency in mixed energy source - mixed culture (MS-MC). Combined works of acid dissolution and Fe(3+) oxidation in MS-MC was responsible for the highest extraction efficiency of 71% for In. Ag was present in the slag as refractory AgPb4(AsO4)3 and AgFe2S3, so extraction did not occur. Copyright © 2015. Published by Elsevier Ltd.
Article
A commercial process for recovery of metals from Indium-Tin-Oxide (ITO) etching industry wastewater by liquid-liquid extraction has been developed. A suitable cross current simulated batch process was developed; extraction mechanisms involved in the process were analyzed. Mathematical models were proposed to correlate metal extractability with respect to extractant concentrations and metal loading with respect to solvent/solution volume ratio. Optimum conditions required for complete scrubbing of Mo and Sn using Cyanex 272, quantitative extraction of pure In using DP-8R were estimated by a proposed model. A good agreement between proposed model and observed results were indicated. Based on the laboratory scale simulation a pilot plant batch process was developed and simulated. The developed process is a techno economical feasible, environment friendly, occupational safe, clean and green process for commercial treatment of ITO etching industry wastewater and recovery of metal values through liquid-liquid extraction. In with 99.999 % purity, Cu nanopowder with 99.999 % purity, Mo and In with 99 % purity has been recovered.
Article
With rapid growth in the use of liquid crystal display (LCD) and increasing concerns for environmental protection as well as conservation of scarce metals such as indium, the recycling of indium from waste LCDs is becoming a hot issue for current society. In this study, the leaching process for indium and explore its mechanism were carried out with full consideration of potential theory and experiments. The optimal parameters for leaching process is controlled at <75µm sample size, 180-min retention time, 50 ? temperature, H2SO4 of leaching agent, 100 g/L initial concentration, and 1:1 of liquid-solid ratio. The initial samples and leaching yields were examined with the necessary analytical techniques including SEM, XRF, EDS, XRD, FTIR, and ICP. We also found leaching process could largely modify raw material and enhance its activation for further recovery. All the obtained results and findings could contribute to affording a closed-loop recycling process for waste LCDs and sustainable development of
Article
Advances in technological development have resulted in high consumption of electrical and electronic equipment (EEE), amongst which are cell phones, which have LCD (liquid crystal display) screens as one of their main components. These multilayer screens are composed of different materials, some with high added value, as in the case of the indium present in the form of indium tin oxide (ITO, or tin-doped indium oxide). Indium is a precious metal with relatively limited natural reserves (Dodbida et al., 2012), so it can be profitable to recover it from discarded LCD screens. The objective of this study was to develop a complete process for recovering indium from LCD screens. Firstly, the screens were manually removed from cell phones. In the next step, a pretreatment was developed for removal of the polarizing film from the glass of the LCD panels, because the adherence of this film to the glass complicated the comminution process. The choice of mill was based on tests using different equipment (knife mill, hammer mill, and ball mill) to disintegrate the LCD screens, either before or after removal of the polarizing film. In the leaching process, it was possible to extract 96.4wt.% of the indium under the following conditions: 1.0M H2SO4, 1:50 solid/liquid ratio, 90°C, 1h, and stirring at 500rpm. The results showed that the best experimental conditions enabled extraction of 613mg of indium/kg of LCD powder. Finally, precipitation of the indium with NH4OH was tested at different pH values, and 99.8wt.% precipitation was achieved at pH 7.4. Copyright © 2015 Elsevier Ltd. All rights reserved.
Article
Flotation tailings dump material of the former lead–zinc mine near Freiberg (Germany) consists of fine grained quartz, feldspar, mica as well as the sulphide minerals pyrite, galena and sphalerite not recovered by flotation. Sphalerite contains, aside from iron, copper and cadmium, significant amounts of indium (up to 0.38% (w/w)) leading to indium contents up to 70 mg/kg in the mine tailings. Prelimi