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Resource Recovery from Waste Electronics has emerged as one of the most imperative processes due to its pressing challenges all over the world. The Printed Circuit Board (PCB) is one of the typical E-waste components that comprise large varieties of metals and nonmetals. Urban Mining of these metals has received major attention all over the world....
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Printed circuit boards (PCBs) constitute an important segment of electronic waste that can be effectively utilized to recover valuable metals and organics. The present work is focused on the kinetics and product distribution from pyrolysis of three different PCB samples, viz., television PCB (TV PCB), motherboard PCB (MB PCB), and hard disk PCB (HD...
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... In comparison to pyrometallurgical methods, hydrometallurgical techniques have a few advantages, such as lower energy interest, easier lab execution, and lower operating costs. Additionally, the use of hydrometallurgical processes frequently results in the recovery of base metals, which may affect the efficiency of conventional filtering methods like particle trade and electrowinning [13]. ...
In today's world, the proliferation of electronic devices has led to a significant increase in electronic waste (e-waste) generation, necessitating the development of innovative approaches for sustainable management. E-waste recycling, which involves the recovery of valuable materials from discarded electronic devices, has emerged as a promising solution to the growing e-waste problem. This article presents an analysis of the current state of research on e-waste management, encompassing various recycling approaches, including mechanical, chemical, and biological methods. The analysis revealed that most of the research on e-waste management has focused on the development of recycling technologies, with a significant emphasis on the use of chemical methods. However, there is a growing interest in the use of biological methods, such as bioreactors and microbial technologies, for e-waste management. Many challenges including lack of uniform regulations, inadequate infrastructure, and high cost of recycling technologies were initiated. The formation of product reuse through remanufacturing, and the deployment of effective recycling facilities are necessary for the management of e-waste. The challenge is to develop innovative and cost-effective solutions to e-waste management (plastic-based e-waste and metals-based e-waste). Several technologies are currently applied to plastic-based e-waste and metals-based e-waste management. primary, secondary, and tertiary recycling of plastic-based e-waste and metallurgical approaches for metals-based e-waste are ideal methods for e-waste management. Furthermore, the techno-economic feasibility of different e-waste recycling approaches was estimated. The analysis suggests that while some recycling approaches are economically viable, there is a need for more research to optimize the efficiency and cost-effectiveness of these methods.
... REEs can be extracted from primary sources (e.g., bastnasite and monazite ores) or recovered from secondary sources (e.g., electronic waste, coal byproducts, and spent FCC catalysts). Biological processes (i.e., bioleaching) have already been widely used in the mining industry to extract high-value metals from low-grade ore, but there are very few reports of biological REE extraction and separation from ore deposits (Arya and Kumar, 2020). REE recovery from electronic and industrial waste has been proposed as a more sustainable way to meet the growing need for REEs. ...
... Low capital costs favour this technique in developing countries, though final liquid and solid waste management aspects are not explicitly discussed in a myriad of studies in the literature (Yong et al., 2019). The coupling of bio-leaching to existing hydrometallurgical operations is also considered (Arya and Kumar, 2020), and the industrial applications are not explicitly reported. ...
E-waste generation has been exponential due to technological advancements, urbanisation and modern lifestyles, reduced replacement intervals of consumer electronics, lack of design-for-environment components in electrical and electronic equipment, lack of repairs and high costs of repairs. 62 million tonnes of e-waste was generated in 2022, equivalent to 7.8 kg of e-waste per person per year. E-waste management has also been challenging, and a significant fraction ends up in landfills despite the presence of precious, base and critical metals. In addition, another substantial fraction is processed by the informal sector employing substandard methods without considering approved environmental, health and safety aspects. Since only 22.3 % of e-waste has been collected and properly recycled, extensive e-waste recycling frameworks, including niche methods, are needed. E-waste co-processing with ore minerals, including mine waste, and metal concentrates and other waste materials in smelters, is thus identified as a promising area to address the e-waste management and value recovery challenge. This is supported by the availability of low-grade ores to produce critical metals and copper and mine tailing management requirements. Integrated pyro-hydrometallurgical facilities in developed countries already process some e-waste with metal concentrates and other waste materials. However, niche e-waste co-processing techniques utilising heap leaching, tank leaching and acid-generating mine tailings are needed since the best available techniques depend on local socio-techno-economic considerations. This study on e-waste co-processing with natural resources and their products could be beneficial to developing the relatively unexplored research area with future studies.
... However, these established methods are deemed unsustainable due to their high costs, the significant pollution they cause, and their substantial energy consumption, amidst other issues [22][23][24]. Biometallurgical processes harness microorganisms to extract metals from solid PCBs, converting them into soluble forms in an aqueous solution by generating lixiviants, which play a pivotal role in the metal extraction process [5,[25][26][27]. The use of such microorganisms holds significant promise because it is environmentally friendly, can operate at ambient temperatures and pressures, is cost-effective, and results in minimal secondary waste generation [28,29]. ...
As the volume of e-waste continues to rise, it is crucial to sustainably manage printed circuit boards (PCBs) and their valuable metal components. PCBs are ubiquitous in modern society, powering a variety of electronic devices. The metal resource crisis and the imperative for a low-carbon circular economy have accelerated the development of e-waste recycling technology. High-value discarded PCBs represent a vital component of e-waste. However, discarded PCBs are deemed hazardous to the ecosystem due to the presence of heavy metals and brominated organic polymers. Thus, recycling metals from discarded PCBs is not only a strategic necessity for fostering a green ecological civilisation but also a crucial guarantee for ensuring a safe supply of mineral resources. This comprehensive review gives the profound details of PCBs, and the performance of and advances in the latest chemical metal recovery methods. Reviewing the latest metal recovery processes, we explored the application of diverse leaching agents, including ionic liquids (ILs), deep eutectic solvents (DESs), organic acids and amino acids. These solvents were assessed in terms of their recovery efficiencies, and most of them demonstrated excellent leaching performance. The role of optimising leaching parameters such as concentration, oxidants, pH, particle size, solid-to-liquid ratios (S/L), temperature, and contact time is underscored, offering insights into achieving sustainable PCB recycling practices. Most of these recent leaching methods successfully extracted base metals (Cu, Fe, Zn, Sn, etc.), as well as precious metals (Au and Ag), achieving leaching efficiencies exceeding 90.0%. Interestingly, their effectiveness can compete with that of traditional hydrometallurgical methods.
... In contrast to the corrosiveness, need for higher temperatures, and health and safety risks associated with inorganic acid leaching (Khanna et al., 2020), spent medium bioleaching operates close to room temperature (25 • C) and at pH levels between 3.3 and 4.0. This highlights the economic advantage of bioleaching over conventional metallurgy in reducing infrastructure costs and energy requirements (Arya and Kumar, 2020). In a techno-economic analysis of REE bioleaching, it was found Fig. 4. Schematic representation of the bioleaching of rare earth elements (REE) from waste printed circuit boards (WPCBs) by the fungal isolate P. expansum. ...
The recovery of rare earth elements (REE) from electronic waste is crucial for ensuring future demand security, as there is a high supply risk for this group of elements, and mitigating the environmental impacts of conventional mining. This research focuses on extracting REE from waste printed circuit boards through bioleaching, addressing the limited attention given to this source. A strain of Penicillium expansum demonstrated efficient bioleaching under optimal conditions of 7.5 initial pH, 0.1 mM phosphate concentration, and excluding a buffering agent. The study achieved significant improvements in La and Tb extraction and enhancements in Pr, Nd, and Gd recovery, approaching 70 % within 24 h. Fungal mechanisms involved in REE extraction included fungal pH control, organic acid biosynthesis, phosphate bioavailability, and potential fungal proton pump involvement. This approach offers a promising solution for sustainable REE recovery from e-waste, contributing to resource security and circular economy.
... However, recent literature on material composition, modern e-waste disassembly, sorting methodologies and metal recovery via ammoniacal solutions is limited [19][20][21]. Review papers on these processes have been published extensively [22][23][24][25]. Our review comprehensively aims to fill this void, concentrating on the latest advancements in e-waste disassembly and sorting techniques, particularly exploring the recovery of metals through ammoniacal solutions (NH 3 /NH 4 + ). ...
The improper disposal of discarded electronic and electrical equipment raises environmental and health concerns, spanning air pollution to water and soil contamination, underscoring the imperative for responsible management practices. This review explores the complex composition of discarded printed circuit boards (DPCBs), crucial components in electronic devices. Comprising substrates, electronic elements and solder, DPCBs showcase a heterogeneous structure with metal (30.0-50.0%) and non-metal (50.0-70.0%) fractions. Notably abundant in precious metals such as Au, Ag, and Pd, DPCBs offer a compelling avenue for recycling initiatives. The inclusion of heavy metals and flame retardants adds complexity, necessitating environmentally sound disposal methods. Ongoing research on smart disassembly, utilising 3D image recognition technology, underscores the importance of accurate identification and positioning of electronic components (ECs). The targeted approach of smart disassembly, centred on valuable components, highlights its significance, albeit with challenges in equipment costs and capacity limitations. In mechanical disassembly, techniques such as grinding and heat application are employed to extract ECs, with innovations addressing gas emissions and damage induced by overheating. Chemical disassembly methods, encompassing epoxy resin delamination and tin removal, present promising recovery options, whilst the integration of chemical and electrochemical processes shows potential. Efficient sorting, encompassing both manual and automated methods, is imperative post-disassembly, with smart sorting technologies augmenting accuracy in the identification and categorisation of ECs. In addition, explorations into NH3/NH4+ solutions for selective metal recovery underscore challenges and stress the necessity for meticulous process optimisation in environmentally sustainable PCB recycling. Challenges and future perspectives have also been expounded.
... Communities engaged in informal e-waste management are exposed to diseases such as blood disorders, congenital disabilities, nausea, asthma, lung diseases and depressed immune systems. Pregnant women miscarry due to high exposure to lead [44]. Exposure to toxic fumes from acid leaching and incineration damages the respiratory system. ...
... Governments are battling with the gobbling up of non-renewable resources, depletion of natural materials, dependence on minerals from conflict zones and the need to reduce the catastrophic effects of improper e-waste handling on the environment and human health [65]. Urban mining can save gold and silver deposits destined for interment, worth $21 billion annually destined for dumpsites and landfills [44,66]. Billions are lost in revenues annually as only 15% of e-waste is recycled [63]. ...
... Although complete recycling of complex e-waste is limited in most African countries, collaborations with partners with state-of-the-art equipment are necessary to complete the process [76]. Recyclers reported marginal profits of between 25 and 30%; hence, urban mining can be a source of livelihood, aggregating different players in the e-waste value chain [44]. ...
The amount of discarded electrical and electronic equipment (EEE), popularly known as e-waste, is rising alarmingly and drawing immediate attention from stakeholders. Governments in emerging economies support importing second-hand EEE to bridge the digital divide and allow communities to access the information superhighway. E-waste contains toxic elements deleterious to the environment and human health. Simultaneously, e-waste contains rare earth minerals that generate USD65 billion in revenue annually through recycling. Urban mining is reclaiming minerals from anthropogenic materials, reducing the extraction of virgin minerals facing depletion and with some sourced from unstable regions and conflict zones. The unidirectional flow of e-waste into Africa from the developed world is viewed as the re-colonisation and the carbonisation divide. Due to a lack of appropriate infrastructure and policies and low knowledge levels in developing countries, the management of e-waste is left to the informal sector, which uses rudimentary tools to extract rare earth metals. This chapter highlights the contentious definition of e-waste, its movement from the Global North, and its epidemiological and environmental impact. It advocates for setting policies and infrastructure to turn landfills and dumpsites into urban mines. This chapter also recommends that developing countries monitor the state of EEE imports and transform informal to formal recycling supported by coordinated collection and storage centres.
... According to the authors, LCD panels can be considered a secondary source of both elements, with industrial routes to recovery involving thermal, aqueous, and biological processing (pyro-, hydro-and biohydrometallurgical processing) (Akcil et al., 2019). E-waste such as LED panels (Cenci et al., 2020), fluorescent lamps , hard disk drives (Talens Peiró et al., 2020), Li-ion batteries (Takahashi et al., 2020), printed circuit boards (Arya and Kumar, 2020b), and discarded mobile phones (He et al., 2020) all feature in the literature. ...
This literature review aimed at analyzing the link between urban mining and the 17 Sustainable Development Goals (SDGs). It seeks to answer the questions: "Does published evidence indicate a relationship between the SDGs and urban mining?", and, if so, "Does the relationship represent a synergy or a trade-off?". The results of this enquiry demonstrate the connection between urban mining and e-waste in the context of the SDG targets for sustainable cities, highlighting convergence between arrangements stemming from different technologies. This suggests that certain SDGs can guide management in a broader and systemic approach, whereby policy-makers can benefit in their daily decision-making. The article stresses the need for social engagement in recycling and reusing processes, as well as the need for an interdisciplinary approach to reach the SDGs' targets for a better future and cleaner cities. The study found a strong connection with some of the targets (6.3, 8.4, 9.4, 9.5, 12.4, and 12.5) and very little connection with others (SDGs 1-5, 10, 14, and 15).
... Demand for critical metals used in the manufacture of advanced technological devices is steadily increasing, while high-strength minerals are rapidly running out. Technological advances, industrial processes, rapid consumption, and the accumulation of significant quantities of valuable materials, including critical metals, in landfills have led to the emergence of a growing global industry known as "urban mining" (European Commission, 2023;Arya and Kumar, 2020;Venkata Mohan et al., 2020). ...
... Demand for critical metals used in the manufacture of advanced technological devices is steadily increasing, while high-strength minerals are rapidly running out. Technological advances, industrial processes, rapid consumption, and the accumulation of significant quantities of valuable materials, including critical metals, in landfills have led to the emergence of a growing global industry known as "urban mining" (European Commission, 2023;Arya and Kumar, 2020;Venkata Mohan et al., 2020). ...
BIOLEACHING OF METALS FROM SECONDARY SOURCES-Review
