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Funding Information: This review was supported by the Academy of Finland project EARMetal (LC, KY, ML: 339979 and LC, KY, JV: 342080). The RawMatTERS Finland Infrastructure (RAMI) funded by the Academy of Finland and based at Aalto University is also acknowledged. Publisher Copyright: © 2023 The Authors One way to overcome the complex problem of the increasing demand for metals coupled with the rapid depletion of high-grade raw materials is to boost research into innovative methods of metal recovery. Electrochemical recovery for metal production has already gained ground in the electrowinning and electrorefining of Cu, Zn, and Au, for example, from highly concentrated and purified hydrometallurgical solutions. Since 2015, an electrochemical technique, based on the combination of the electrodeposition (ED) and redox replacement (RR) processes, has been developed in the context of trace metal recovery (μg/L – mg/L). Specifically, EDRR enables the efficient recovery of precious metals, including Ag, Au, Pt, and Te, from underutilized secondary raw materials-hydrometallurgical solutions, where these metal species are naturally present. With highly flexible electrochemical process parameters, EDRR also allows controllable preparation of metal coatings, nanoparticles, and even functional surfaces directly from lower-grade resources, further indicating the promise of EDRR to relieve material scarcity. In this review, we analyze in detail the significant progress regarding EDRR for both metal recovery behavior and creation of high-value-added materials. The future prospects for EDRR, including energy efficiency and sustainable materials, are also outlined.

EoL of new aircraft integral welded panels of 3rd generation of Al-Li alloys welded between them by Laser Beam Welding (LBW) and Friction Stir Welded (FSW), including new Cr-free coatings to protect them was investigated. The best EoL route including dismantling and recycling procedures was defined for 10 different combinations of FSW/LBW Al-Li alloys and two coatings. Different cutting strategies, ranging from cutting only for size reduction to full separation of all materials, including the separation of the welded seam were defined with the objective to recycle the maximum amount of material to manufacture high quality aircraft Al-Li alloys. Furthermore, the need to eliminate primer and topcoats and different decoating methods were investigated for TFSAA (Thin film Sulphuric Anodizing) and Sol Gel coatings. The separated metallic fractions of the different EoL routes were recycled and the produced metallic alloys characterised in order to establish a ranking in terms of costs, environmental impact and effectivity, that allowed to select the best option for recycling for each LBW and FSW panels. Fading/enrichment of the different elements were researched, and the recycled alloys were compared with commercial primary Al-Li alloys to determine the compatibility with each of them. Materials and energy flows, emissions and waste generation were inventoried during the new End of Live process tested and provided to ecoTech project for the Life Cycle Assessment (LCA). The best EoL route was defined to valorize as much as possible of the valuable alloying elements and minimize the environmental impact: cutting only for size reduction (6 FSW and 3 LBW configurations) and full separation of all materials (1 LBW configuration).

The end of fife (EoL) of new aircraft panels made of Al-Li alloys in which the stringers and skin were joined, either by laser beam welding (LBW) or by friction stir welding (FSW), was investigated at the lab scale. Different cutting strategies, ranging from cutting only for size reduction to full separation of all materials, including the removal of the welded seam, were defined, with the objective of recycling the maximum amount of panel scrap back into high-quality aircraft Al-Li alloys. Those welded aerostructures were coated with two novel Cr-free coating systems. The effect of the coatings on the recyclability of the panels and the need to eliminate the primer and topcoats were researched. Fading/enrichment of the alloying elements during recycling was determined. The chemical compatibility of the recycled alloys with four commercial Al-Li alloys was examined. The EoL route that maximized closed-loop recycling and the conservation of the valuable alloying elements was identified. Nine out of the ten configurations were found to be compatible with joint recycling. Only the LBW structure with ER4047 filler wire required sorting into scrap fractions and removing the weld seam. Decoating by corundum blasting followed by cutting before remelting is the recommended EoL process.

Scrapped saggars, used for the calcination of the cathode materials of lithium-ion batteries, contain large amounts of nickel, cobalt and manganese compounds, which have high economic value and significance to the ecological environment if recycled. This paper uses the life cycle assessment method to evaluate the environmental impact of the recycling process, compares its impact intensity with that of the direct disposal of Ni-Co-containing saggars and the production of corresponding products with alternative processes, and then compares the impact of each process. Sensitivity analysis of each material input and output item is carried out to find whether the input or output item that has a greater impact on the environment. The results show the following: (1) the environmental impact of the recovery of Ni-Co-containing saggars is much lower than that of equivalent products produced by alternative production methods, and the weighted person equivalent is only 14.5% of the alternative process; (2) from the perspective of processes, the crystallization and leaching processes demonstrate the greatest impact; and (3) among all input and output items, the sulfuric acid input in the reduction and leaching process, the potassium carbonate and steam input in the crystallization process, the potassium carbonate and potassium hydroxide input in the cascade separation process, and the ammonia input in the purification process are the items with the greatest environmental impact, accounting for 86.05% of the overall environmental impact sensitivity and becoming the focus of future process improvement.

For minor metal recycling from electric parts, detachment without breakage (non-destructive detachment) of the electric parts from printed circuit boards (PCBs) is required. A cross-flow shredder (CFS), a drum-type chain mill, is often used in PCB recycling, but the effects of its individual features (e.g., chain thickness) on the non-destructive detachment of the PCB parts have yet to be understood. In this study, a CFS suited to the design-of-experiment (DoE) approach was developed; 27 different experimental conditions were evaluated, with three repetitions under each condition for a single PCB crushing, and the effect of nine CFS factors on the non-destructive detachment of parts from the PCBs of mobile phones was investigated. It was revealed that two factors (rotation rate and vent screen) have a statistically significant influence on such non-destructive detachment, and two other factors (chain-wall distance and crushing time) have a significant influence on related results such as the overcrushing of boards (PCBs after parts detachment) and powder generation. Based on these results, a future perspective on CFS improvement is presented.

The concept of Circular Economy (CE) and its main strategy recycling are seen as one of the most important measures to achieve sustainable development. Meanwhile, however, concerns are being raised in the scientific community about the conceptualization and orientation of CE. One major issue is that CE is in danger of becoming an end in itself, with the goal of completely closed material cycles. Its contribution to sustainable development is gradually fading into the background. To contribute to this ongoing discussion, we focus in our article on the recycling of metals as part of CE and its contribution to climate protection, as one of the main aspects of sustainable development. Based on life cycle assessment and substance flow modelling carried out in our previous works, we show that metal recycling in most cases requires much less energy and therefore results in much lower greenhouse gas (GHG) emissions than primary production. However, this is by no means without limitations. We show empirically that metal concentration is a significant factor that determines the energy required for recycling. If the metals are too diluted in the technosphere, as it is indeed the case for several metal applications, their recycling require much more energy than the alternative primary production, and thus intensifying rather than mitigating climate change.

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works While deep learning has helped improve the performance of classification, object detection, and segmentation in recycling, its potential for mass prediction has not yet been explored. Therefore, this study proposes a system for mass prediction with and without feature extraction and selection, including principal component analysis (PCA). These feature extraction methods are evaluated on a combined Cast (C), Wrought (W) and Stainless Steel (SS) image dataset using state-of-the-art machine learning and deep learning algorithms for mass prediction. After that, the best mass prediction framework is combined with a DenseNet classifier, resulting in multiple outputs that perform both object classification and object mass prediction. The proposed architecture consists of a DenseNet neural network for classification and a backpropagation neural network (BPNN) for mass prediction, which uses up to 24 features extracted from depth images. The proposed method obtained 0.82 R2, 0.2 RMSE, and 0.28 MAE for the regression for mass prediction with a classification performance of 95% for the C&W test dataset using the DenseNet+BPNN+PCA model. The DenseNet+BPNN+None model without the selected feature (None) used for the CW&SS test data had a lower performance for both classification of 80% and the regression (0.71 R2, 0.31 RMSE, and 0.32 MAE). The presented method has the potential to improve the monitoring of the mass composition of waste streams and to optimize robotic and pneumatic sorting systems by providing a better understanding of the physical properties of the objects being sorted.

South Korea is a resource-dependent country that relies on the import of most metal resources. Therefore, we should save resources through recycling. In particular, the recycle rate of non-ferrous metals is very low. This is due to the limitations of the recycling technology currently in use. To overcome these limitations, non-ferrous metal recycling studies using laser induced breakdown spectroscopy are underway. In this paper, we will discuss an automatic metal classification system that receives metal information from a laser-induced breakdown spectrum and classifies a metal scrap by material. Currently, sorting systems use non-contact pneumatic systems. Compared to the contact method, the system is durable and is controlled at high-speed. This is because the system does not directly contact the metal scrap. Therefore, we will study how to effectively use the flow rate by modeling the pneumatic system.

The article deals with the most effective primary utilization and subsequent processing of the main waste of machine-building enterprises-metal chips. To solve the above problems, the recycling of metal waste the most effective method is a comprehensive approach to the conditions of machine-building enterprises working in the conditions of the automated production consists of solutions to several problems, the main of which are submitted to the necessary properties of the chips produced and optimization of the technological equipment used for initial processing and subsequent briquetting of the chip. The solution of the problem of obtaining chips of the specified characteristics after the analysis of existing methods of its solution is proposed to be performed by applying the method of preliminary local physical impact on the surface of the workpiece. The proposed method makes it possible to obtain chips of such parameters that will meet the technical conditions of the type of automatic line for its processing and disposal, which is available in a particular production. The problem of optimization of the technological line of primary processing of chips is proposed to be solved on the basis of preliminary engineering analysis of chip crushing devices, which allows you to choose the optimal geometry of the cutter inserts depending on the type and material of the chips being crushed. The proposed set of measures should help machine-building enterprises to increase the profitability of production.

One of the most promising innovation strategies for sorting and recycling post-consumer aluminium scrap is using quantitative Laser-Induced Breakdown Spectroscopy (LIBS) analysis. However, existing methods to estimate alloying element concentrations based on LIBS spectra, such as linear univariate regression and Machine Learning models, are still too limited in their performance to achieve the accuracy demanded by the industry. Therefore, this study presents novel Deep Learning approaches and compares their performance to those of traditional univariate regression and Machine Learning methods in terms of RMSE, MAE, and R2 value. For this evaluation, two sample sets of aluminium pieces are used: one containing 27 certified aluminium reference samples and the second containing 733 post-consumer scrap pieces for which the ground truth concentrations are determined by X-Ray Fluorescence (XRF). Adopting multiple loss functions, one for each element, has proven its significant value for the regression performance. It improves the results for all performance metrics in the Scrap Sample set, and the same is true for the Reference Sample set, except for the coefficient of determination of Fe, Mn and Mg. In addition, the proposed methodology considers the learning prioritisation problem to prevent that learning the concentration of the base element is prioritised over the alloying elements. Although the effect of excluding the base alloy aluminium from the learning is small and not always positive for the performance, demonstrating this effect is also considered valuable. Since the average RMSE on the prediction is just 0.02 wt% for Al and Si, and not more than 0.01 wt% for Fe, Cu, Mn, Mg, and Zn, the best-performing Deep Learning model shows promise for the future of LIBS in metal sorting applications.

Recycling of waste is critical for sustainability. Modern industrialization has caused a rapid decline in natural resources, and a dramatic rise in hazardous pollutants released into the environment. A recent study reported that global resource usage rose from 23.7 billion tons in 1970 to 70.1 billion tons in 2010. Global consumption of metals has increased at a significant pace, placing severe environmental and economic pressure for recycling. Electrochemical processes are particularly well suited for metal recovery. Due to the ionic nature of the metals after leaching, both Faradaic and non-Faradaic electrochemical processes can play an important role in separating and purifying these elements. Here, an overview of electrochemical approaches for chemical recycling will be presented, with a focus on metal recovery from electronic waste, battery components, as well as methods for selective recycling specialty metals and rare earth elements. This article discusses emerging recycling methods for value-added compounds beyond metals, including organic compounds, which may point to new directions in chemical recycling. In sum, electrochemical separation processes are expected to play a significant role in waste recycling and contribute towards a sustainable circular economy.

Recycling of waste electrical and electronic equipment has become an urgent global issue in recent years from the prospectives of resources recycling and environmental protection. In the present work, the recycling of waste memory modules (WMMs) through low-temperature alkali melts was investigated, based on the thermodynamic analysis of the nonmetallic reactions of brominated epoxy resin, glass fiber and memory chip with the molten mixed alkali. The effects of the reaction temperature and the ratio of alkali mixture on the removal rate of nonmetallic parts in WMMs were discussed under the condition of air atmosphere. The optimum process parameters were further confirmed by in-situ monitoring of the temperature during the whole reaction process. The mixtures with Cu, Fe and Ni as the main components were obtained after the treatment of WMMs in the molten alkali. These mixed metals were further separated into copper-rich and ferronickel-rich metals by physical magnetic separation. Moreover, the precious metals Au and Ag were enriched in Cu-rich alloys. This work provided an efficient and environment-friendly method for metal recycling from WMMs.

The metal recycling industry provides jobs, generates revenue in local communities and conserves energy and resources. Nonetheless, possible negative impacts of metal recyclers (MRs) include the potential for emissions of metal aerosols and other dusts, noise, traffic and fire during operations. In Houston, Texas, there were more than 180 resident complaints about air quality related to MRs from 2006 to 2011 that were reported to the city’s 311 call system. As a part of a community-based participatory research study, Metal Air Pollution Partnership Solutions (MAPPS), we evaluated the impact of metal emissions from MRs on air quality over two years in four environmental justice communities. We simultaneously collected samples of inhalable particles (aerodynamic particle size less than 10 μm, PM10) using a sampling strategy to capture emissions from the MRs while they were in operation at four locations within each community: an upwind location, the fence line of MR and two downwind locations and analyzed the samples for 10 metals. The highest values of iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), arsenic (As) and chromium (Cr) were detected at the fence lines of MRs. The normalized ratios of these metals at near and far neighborhood locations were 0.01 to 0.64 and 0.01 to 0.34, respectively, as compared with the metals at the fence line. The concentrations of metals rapidly decreased by 57–70% within 100 meters and reached similar levels at upwind (background) locations at approximately 600 meters. After adjusting the measured data for wind direction, rain and operating hours, we calculated non-carcinogenic hazard index values and carcinogenic risks for adult residents from breathing metals emitted from the facilities. Estimated inhalation cancer risks ranged from 0.12 case to 24 cases in 1 million people and the hazard index values ranged from 0.04 to 11. Implications: In Houston, Texas, residents complained about air quality related to metal recyclers from 2006 to 2011. Using a community-based participatory research method, metal emissions were characterized at four environmental justice communities. The results indicate that metal concentrations were the highest at the fence line and decreased by 57–70% within 100 meters and reached similar levels of background at 600 meters. After adjusting the measured data for meteorological parameters and operating hours, estimated inhalation cancer risks ranged from 0.12 cases to 24 cases in 1 million people and hazard index values ranged from 0.04 to 11.

Damage healing in steel parts enables them to be reused again without going through the conventional metal recycling/remelting process, thus damage healing is a process with potential for reclaiming products while causing less environmental damage, that is, improving resource efficiency. In this paper, damage healing of a porous free cutting steel during a hot flat rolling process has been investigated. A UMAT subroutine incorporating damage healing models has been utilised which includes two stages: void closure and diffusion bonding. The developed UMAT subroutine captures evolution of void volume fraction (vvf) as a result of plastic compression, to model the void closure process and predict the subsequent healing time. Effects of roll gap geometry factor (RGF), initial porosity size (void volume fraction) on porosity elimination during rolling have been investigated.

Spotting radioactive material in waste is of paramount importance for environment protection. This is particularly challenging when orphan sources are hidden in scrap metal that shields their activity from the traditional detectors in the portals scanning incoming trucks. In order to address this issue, we present a wireless and compact SiPM-based gamma spectrometer compatible with strong magnetic fields (0.1 T) to be installed in the bore of the lifting electromagnets to scan reduced volumes of metal and thus achieve higher sensitivity. The microcontroller-based instrument provides 11% energy resolution (at 662 keV), an energy range from 60 keV to 1.5 MeV, a max. count rate of 30 kcps, a weight

With the rapid development of China’s new energy industry, the use of lithium-ion batteries has increased sharply, and the demand for battery cathode metals such as nickel, cobalt, and manganese has also increased rapidly. Scrapped ceramic saggars that are used to produce the cathode materials of lithium-ion batteries contain large amounts of nickel, cobalt, and manganese compounds, thus, recycling these saggars has high economic value and ecological significance. In this paper, the emergy method is used to analyze the ecological benefits of the typical Ni–Co-containing saggar recycling process in China. This paper constructs an ecoefficiency evaluation index for industrial systems based on emergy analysis to analyze the recycling of nickel and cobalt saggars. The ecological benefits are analyzed, and the following conclusions are drawn. (1) The Ni–Co-containing saggar recycling production line has good economic and ecological benefits. (2) The process has room for improvement in the energy use efficiency and clean energy use of the crystallization process and the efficiency of chemical use in the cascade separation and purification process. This study also establishes a set of emergy analysis methods and indicator system for the evaluation of the ecological benefit of the recycling industry, which can provide a reference for the evaluation of the eco-economic benefit of similar recycling industry processes.

In the recycling industry, the use of deep spectral convolutional networks for the purpose of material classification and composition estimation is still limited, despite the great opportunities of these techniques. In this study, the use of Laser-Induced Breakdown Spectroscopy (LIBS), Machine Learning (ML), and Deep Learning (DL) for the three-way sorting of Aluminum (Al) is proposed. Two sample sets of Al scrap are used: one containing 733 pieces for pre-training and validation with a ground truth of X-Ray Fluorescence (XRF), and the second containing 210 pieces for testing for unknown compositions. The proposed method comprises a denoising system combined with a method that extracts 145 features from the raw LIBS spectra. Further, three ML algorithms are assessed to identify the best-performing one to classify unknown pieces of aluminum post-consumer scrap into three commercially interesting output classes. The classified pieces are weighed, melted, and analyzed using spark analysis. Finally, to optimize the best-performing ML system, three state-of-the-art denoising and three feature extraction networks are pre-trained for learning the baseline correction and the proposed feature extraction. Transfer Learning from the six pre-trained networks is applied to create and evaluate 24 end-to-end DL models to classify Al in real-time from >200 spectra simultaneously. The end-to-end DL scheme shows the advantages of learning and denoising the spectra, allowing the transfer of traditional spectral analysis knowledge and the proposed feature extraction into DL, where the network learns from the entire spectrum. The best results for ML and DL were obtained with Random Forest processing one spectrum in 150 ms and BPNN+GHOSTNET(Fine-tuning) processing 200 spectra in 9 ms, which achieved 0.80 Precision, 0.81 Recall, 0.80 F1-score, and 0.80 Precision, 0.79 Recall, 0.79 F1-score, respectively.

The rapid development of lithium-ion batteries (LIBs) in emerging markets is pouring huge reserves into, and triggering wide interest in, as the popularity of electric vehicles is driving the explosive growth of EV LIBs. These mounting demands are posing severe challenges to the supply of raw materials for LIBs and producing an enormous quantity of spent LIBs, bringing difficulties in the areas of resource allocation and environmental protection. This review article presents an overview of the global situation of power LIBs, aiming at different methods to treat spent power LIBs and their associated metals. We provide a critical review of power LIB supply chain, industrial development, waste treatment strategies and recycling, etc. Data show that power LIBs will form the largest proportion of the battery industry in the next 30 years, at a dramatically increasing rate. The analysis of the sustainable supply of critical metal materials is emphasised, as recycling metal materials can alleviate the tight supply chain of power LIBs. The existing significant recycling practices that have been recognised as economically beneficial can promote metal closed-loop recycling. Scientific thinking needs to innovate sustainable and cost-effective recycling technologies to protect the environment because of the chemicals contained in power LIBs.

The effects of pyrolysis on the composition of the battery cell materials as a function of treatment time and temperature were investigated. Waste of Li-ion batteries was pyrolyzed in a nitrogen at...

Nowadays, solid waste has become a major problem in Malaysia. However, most people in Malaysia are not aware and take this problem for granted. The rising number of population and massive development in recent years indirectly generated an enormous value of household waste, making the household waste the main generator for solid waste in Malaysia. It stated that only 5 percent of an average 30,000 tons of waste have been recycled in Malaysia. The purpose of the paper is to design a system to separate the metal recyclable household waste automatically and record the data waste collected. There are total of four detectors used to separate the non-metal, steel, copper and aluminum metal waste. The average time used to complete metal separation process by using the proposed prototype is 14.5 seconds. This paper includes a mechanical part, programming part, an electronic design and also the data collected from this proposed system. The system will be programmed using Arduino Mega as a microcontroller to control all the electronic component in the system.

This paper presents an integrated approach to the identification of complex re-processing operations of ancient ferrous artefacts from the multi-period site of Saruq al-Hadid, Dubai, United Arab Emirates. Spatial and morphological studies and a range of archaeometric analyses – optical microscopy, X-Ray diffraction, Micro-Raman spectroscopy, neutron tomography – are used to identify various processing markers preserved in these heavily corroded objects and to distinguish two groups of differently processed fragments. The main analytical focus is the investigation of corrosion layers preserving traces of hot oxidation and forging of metallic iron, along with re-heating of previously formed rust layers. The collected evidence suggests that the numerous iron artefacts ritually deposited of at the site in the early Iron Age were subsequently retrieved and re-forged into semi-products as a part of larger scheme of recycling operations, in which Saruq al-Hadid was a first node.

In this study, the chelating extraction of base metals namely, Cu, Zn, Ni from printed circuit board (PCB) of obsolete computer was carried out using diethylene triamine pentaacetic acid (DTPA) as a safer ligand. At a liquid to solid ratio (L/S ratio) of 50 and the comminuted PCB in the size range of 0.038–1 mm, the maximum extraction of around 97% Cu at 4.5 d and more than 99% each of Zn and Ni at 3 d was achieved using 0.5 M DTPA at pH of 9, temperature of 50 °C and mixing speed of 450 rpm. Using 0.9 M H2O2 under optimized process conditions, around 99% Cu and 82% Ni leaching were achieved in 8 h along with complete leaching of Zn in 1 h only. Kinetics development using the shrinking core model (SCM) indicated that the metal extraction from the PCB comminution fines using DTPA is controlled by diffusion process. Further, metal recovery of around 98% each for Cu and Ni and 95% for Zn was achieved by the chemical precipitation of the leachate. Chelating extraction using DTPA coupled with the chemical precipitation of the leachate has the potential to emerge as a complete solution for metal recycling from e-waste.

The pyrolysis experiment was carried out on the waste printed circuit boards (WPCBs) of mobile phones to obtain the mixed metals which contains more than ten valuable metals. The main components in the mixed metals are elements Fe, Cu, Pb, Sn. The liquid-liquid phase separation behavior of (Fe0.4Cu0.6)100-xPbx ternary alloy has been studied. The introduction of Pb into the metastable immiscible Fe-Cu alloy can result in a stable liquid-liquid phase separation into L(Fe) and L(Cu,Pb) liquids. With the increasing of Pb content, the second phase separation in the residual L(Cu,Pb) liquid was detected, resulting in the formation of three-zone-separation structure. On this basis, a hierarchical separation system was designed to recycle mixed metals in super gravity field. The results show that the metals Cr, Co, Ni, Si are mainly enriched in the Fe-rich zone, the precious metals Au, Ag and a small amount of Zn are concentrated in the Cu-rich zone, while the low-melting-point metals Sn, Bi, Cd, and In are collected in the Pb-rich zone.

The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming to assess the auto-catalyst-derived environmental impact to the large city of Athens and the potential human health risk. The determined mean values of 314 Pt, 510 Pd, and 23 Rh (all in μg/kg) in dust samples are much lower than the 2070 μg/kg Pt and 1985 μg/kg Pd contents in gully pots in the Katechaki peripheral highway and higher than the mean values of 230 Pt, 300 Pd, and 13 Rh (all in μg/kg) in the soil samples. With the exception of two samples from gully pots, from 51% to 70% of the samples (for the Pd and Pt, respectively) fall in the range from 100 to 400 μg/kg. The calculated accumulation factors showed means of 3.88 μg/kg Pd and 2.95 μg/kg Pt for plants and tree leaves, but any significant difference (t-test) is lacking, and they are much lower than those reported for roots of plants (literature data). Although the Pt, Pd, and Rh bioaccumulation factors for shoots of plants/crops are relatively low, the increasing number of cars with catalytic converters in Greece and the relatively high bioaccumulation in the food chain may highlight a potential risk for human health and ecosystems, and the need for special attention on their bioaccumulation and bioaccessibility on a global scale.

The process to extract rhenium from a superalloy is an immense technical challenge due the complex chemistry involved. Being one of the rarest elements in the earth’s crust the scarcity and cost of rhenium makes it advantageous to recover the element from scrap superalloy. In this research the separation and monitoring of the different stages of the recycling process to extract rhenium from CMSX-4 superalloys using a distillation process were performed. This novel method combining distillation and use of exchange resins was used to separate rhenium from a complex mixture of metals in the CMSX-4 superalloy. The identification and quantitation of perrhenate and contaminants were performed by atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), ion chromatography (IC) and Scanning Electron Microscopy- Energy Dispersive X-Ray (SEM-EDX). Perrhenate ions were extracted with purity close to 93%. The analytical characteristics for a novel infrared method to quickly identify perrhenate anions from CMSX-4 are presented. The main characteristics of the analytical validation were: LoD: 0.5% w/w; LoQ: 1.5% w/w; linear range 1.5-100% w/w; correlation coefficient R2 = 0.9905; precision (%RSD) for 10%w/w = 6.6 and 75%w/w = 4.1, respectively; accuracy (%) for 10% w/w 99.6% and 75% w/w=101.1, respectively.

Orientador: Sergio Tonini Button Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica Resumo: Nas últimas décadas, a concorrência entre as indústrias vem ficando cada vez mais acirrada. Tem-se visto um movimento mundial no sentido de melhorar a competitividade, através de melhorias de qualidade nos produtos e serviços, redução de custos através da melhoria da produtividade, redução de quadro de pessoal e aumento da eficiência dos processos. O atendimento às normas e legislação ambientais também tem contribuído para a imagem das companhias, atuando a favor da sua competitividade. As empresas produtoras de baterias automotivas têm uma margem de lucro bastante reduzida por unidade produzida, portanto precisam produzir em larga escala, para serem lucrativas. A variabilidade dos processos, tanto administrativos quanto industriais, provoca desvios e gastos de recursos desnecessários, que devem ser eliminados. A intenção deste trabalho é demonstrar como ferramentas estatísticas podem ser utilizadas para reduzir a quantidade de borra de ligas de chumbo enviada para reciclagem externa, gerada na fundição de bobinas para a expansão de grades de baterias automotivas, através da utilização da filosofia Seis Sigma. O objetivo do trabalho foi atingido como se pode observar pela expressiva redução do nível de PPM atingido e sua conseqüente redução de custo. A redução de 55,4 % na quantidade de borra gerada significou menos resíduos de chumbo em circulação nas estradas e menos manuseio do material que, embora transportado na fase metálica, possui uma parte que se oxida e fica na forma de pó. Abstract: In recent decades, the competition between industries is becoming increasingly fierce. It has seen a worldwide movement to improve competitiveness through quality improvements in products and services, reducing costs by improving productivity, reducing staff and increasing the efficiency of processes. The service standards and environmental legislation has also contributed to the image of companies, acting in favor of its competitiveness. The manufacturers of automotive batteries have a profit margin greatly reduced per unit of output, so they must produce on a large scale to be profitable.The variability of processes, both administrative and industrial to deflections and spending unnecessary resources, which must be eliminated. The intention of this work is to demonstrate how statistical tools can be used to reduce the amount of sludge lead alloys sent for recycling outside, generated in the casting reels for expanding grids of automotive batteries through the use of Six Sigma philosophy. The objective was achieved as shown by the significant reduction in the level of PPM achieved and the consequent cost reduction. The 55.4% reduction in the amount of sludge generated meant less waste lead in circulation on the roads and less handling of material that, while carried in metallic phase, has some rust and it is in powder form. Mestrado Materiais e Processos de Fabricação Mestre em Engenharia Mecânica

During the steel production process, nearly twice as many input materials are used as compared to finished products. This creates a large amount of post-production waste, including slag, dust, and sludge. New iron production technologies enable the reuse and recycling of metallurgical waste. This paper presents an investigation on the reduction of selected iron-bearing waste materials in a laboratory rotary furnace. Iron-bearing waste materials in the form of dust, scale, and sludge were obtained from several Polish metallurgical plants as research material. A chemical analysis made it possible to select samples with sufficiently high iron content for testing. The assumed iron content limit in waste materials was 40 wt.% Fe. A sieve analysis of the samples used in the subsequent stages of the research was also performed. The tests carried out with the use of a CO as a reducer, at a temperature of 1000 °C, allowed to obtain high levels of metallization of the samples for scale 91.6%, dust 66.9%, and sludge 97.3%. These results indicate that in the case of sludge and scale, the degree of metallization meets the requirements for charge materials used in both blast furnace (BF) and electric arc furnace (EAF) steelmaking processes, while in the case of reduced dust, this material can be used as enriched charge in the blast furnace process. Reduction studies were also carried out using a gas mixture of CO and H2 (50 vol.% CO + 50 vol.% H2). The introduction of hydrogen as a reducing agent in reduction processes meets the urgent need of reducing CO2 emissions. The obtained results confirm the great importance and influence of the selection of the right amount of reducer on the achievement of a high degree of metallization and that these materials can be a valuable source of metallic charge for blast furnace and steelmaking processes. At an earlier stage of the established research program, experiments of the iron oxides reduction from iron-bearing waste materials in a stationary layer in a Tammann furnace were also conducted.

This mini-review article summarizes the available technologies for the recycling of heavy metals (HMs) in municipal solid waste incineration (MSWI) fly ash (FA). Recovery technologies included thermal separation (TS), chemical extraction (CE), bioleaching, and electrochemical processes. The reaction conditions of various methods, the efficiency of recovering HMs from MSWI FA and the difficulties and solutions in the process of technical development were studied. Evaluation of each process has also been done to determine the best HM recycling method and future challenges. Results showed that while bioleaching had minimal environmental impact, the process was time-consuming. TS and CE were the most mature technologies, but the former process was not cost-effective. Overall, it has the greatest economic potential to recover metals by CE with scrubber liquid produced by a wet air pollution control system. An electrochemical process or solvent extraction could then be applied to recover HMs from the enriched leachate. Ongoing development of TS and bioleaching technologies could reduce the treatment cost or time.

Effective recycling of metallic waste and end-of-life vehicles (ELVs) is of crucial importance. Currently used separation and sorting techniques result in the formation of fine residue (usually below 10–20 mm) called shredder fines. Shredder fines contain the so-called ‘fluff' (i.e., foam, wood and textile fibres) with metal particles entangled in it. This ‘fluff' interferes with sorting techniques and thus reduces the metal recycling rate. For this reason, presently, shredder fines are primarily landfilled, which is not covered by the greater objective of the circular economy; therefore, the need for their recycling emerged. Low-temperature pyrolysis (torrefaction) increases the ‘fluff' fragility and thus liberates the metal particles without their substantial oxidation, thereby enabling their recycling. For that reason, in this article, shredder fines torrefaction was performed at the temperature range of 250–450 °C. The process products were comprehensively characterised using, among others, MicroGC (non-condensables), GC/MS (condensables), and ICP-SFMS (char). The possible application of the torrefied shredder fines after the metal sorting was discussed as well. Torrefaction was identified as a promising way of shredder fines recycling, and the torrefied shredder fines after metals sorting have the potential to be used as an ingredient of a raw material mix for cement kilns.

Global digitisation and availability of affordable and advanced electrical and electronic equipment (EEE) have aggravated the management problem of waste electrical and electronic equipment (WEEE) or electronic waste (e-waste) around the world. According to a report published by Balde et al. (2017), global electronic waste (e-waste) generation in the year 2016 is estimated to be 44.7 Mt and projected to grow to 52.2 Mt by 2021. EEE has been categorised into two categories: (a) Information technology and telecommunication (IT and telecom) equipment and (b) consumer electrical and electronics (e-waste management rules, 2016). End-of-life mobile phones (Eol-MPs) are contributing a major portion in e-waste content because of its high obsolescence rate and ever-increasing consumer base and year-wise sales as shown in Fig. 1 (Beigl et al., 2012; Kasper et al., 2011; Monteiro et al., 2007; Osibanjo and Nnorom, 2008; Robinson, 2009). Printed circuit board (PCB) is the core component of any EEE so as of end-of-life mobile phone (EoL-MP). Metal recycling from the PCBs of EoL-MP as a secondary resource has become a necessity both from an economical and environmental point of view considering the abundant presence of base, precious and toxic metals in them.

It is well understood that waste or scrap is a by-product of daily activities and social behavior. Waste could originate from various sectors and encompasses various components that renders it quite attractive to valorize and develop various valuable products out of. Waste could originate from industrial sectors that render it hard to classify, such as the case in end-of-life tires or industrial scrap. Both of which contain a hefty proportion of metallic fractions that make them quite attractive to reuse. To put things into a better perspective, the Oxford English Dictionary defines scrap as “odds and ends, leavings; waste material.” For hundreds of years, waste materials were viewed as undesired substances that must be disposed of after their primary use. Recycling in modern societies has received great attention since it provides the means for generating value from scrap materials. This chapter aims to provide a critical insight on the challenge of sustainable development that has been started from the last century, dedicated to develop cost-effectiveness processes for metallic-based recycles. It will also discuss the current technologies employed for metal recovery and recycling from waste to high purity metallic feedstock production, that can be used in both traditional and high-tech applications. Here we will focus on the recycling of iron (Fe) and copper (Cu) metals and their alloys, originating from various sectors. Moreover, a detailed discussion on the new applications of the recycled metals in different sectors will be provided. This chapter will also present research insights and case studies of metal recycling and their advanced applications. This chapter provides a Birdseye view of possible integrated waste management holistic approaches that can render such metallic waste of high end value to the chain of waste management.

This study assesses the environmental performance of the municipal solid waste (MSW) incineration bottom ash (IBA) treatment plant in Hinwil, Switzerland, a large-scale industrial plant, which also serves as a full-scale laboratory for new technologies and aims at an optimal recovery of metals in terms of quantity and quality. Based on new mass-flow data, we perform a life cycle assessment that includes the recovery of iron, stainless steel, aluminium, copper, lead, silver and gold. Fraction-specific modelling allows for investigating the effect of the metal fraction quality on the subsequent secondary metal production as well as examining further metal recycling potentials in the residual IBA. In addition, the implications on the landfill emissions of IBA residues to water were quantified. The impact assessment considered climate change, eco- and human toxicity and abiotic resource depletion as indicators. Results indicate large environmental savings for every impact category, due to primary metal substitution and reduction of long-term emissions from landfills. Metal product substitution contributes between 75% and >99% to these savings in a base scenario (1′000-year time horizon), depending on the impact category. Reductions in landfill emissions become important only when a much longer time horizon was adopted. The metal-based analysis further illustrates that recovering heavy non-ferrous metals – especially copper and gold – leads to large environmental benefits. Compared to the total net savings of energy recovery (215 kg CO2-eq per tonne of treated waste, average Swiss plant), enhanced metal recovery may save up to 140 kg CO2-eq per tonne of treated waste., Waste Management, 119, ISSN:0956-053X, ISSN:1879-2456

International audience; Deep eutectic solvents (DESs) appeared recently as a new class of green designer solvents. The recovery of metals using hydrometallurgy is of major importance with the growth in metal demand. Several authors used these solvents for the hydrometallurgical recovery of metals from primary and secondary resources, and these studies are reviewed in the present work. Hydrophilic DESs can be used for the leaching of metals and have great potential to replace mineral acids, and even to reduce water consumption. Efficient and selective leaching of metals from minerals or wastes is feasible by using DESs. However, the kinetics of leaching as well as the physicochemical properties of DESs are still limiting their large-scale application. Electrochemical recovery from DES is also possible but deserves further investigation. Finally, the recovery of metals from aqueous solutions using hydrophobic DESs was studied in several works. For the solvent extraction of metals, hydrophobic DESs constitute credible alternative ionic liquids.

Western Metals Recycling (WMR), a subsidiary of NUCOR Steel, is a metals recycling company with a location in Plymouth, Utah. At Plymouth, a 50 NT/hr. non-ferrous recovery plant uses eddy current technology to generate a non-ferrous product called zorba. Zorba is a mix of aluminum, copper, brass, zinc, printed circuit boards, coins, lead, and the like. (Figure 1) The market value of zorba varies but generally ranges from $0.30 to $0.50 per pound. The value of the coins (not including pennies) is much higher than zorba price. The team's objective is to upgrade and optimize the existing trommel equipment to sort the zorba into coin-sized denominations with greater than 90% accuracy.

A transient three-dimensional comprehensive numerical model was established to study ion transport caused by diffusion, convection, and electro-migration in the electro-refining process for scrap-metal recycling. The Poisson–Nernst–Planck equations were used to define ion transport within the electrolyte, while the Naiver–Stokes equations and the energy equation were employed to describe fluid flow and heat transfer. In addition, the Butler-Volmer formulation was used to represent the kinetics of the electrochemical reaction. The comparison between the measured and simulated data indicates the reliability of the model. Under the action of diffusion and electro-migration, the positive copper ion moves from the anode to the cathode, while the negative sulfate ion migrates in the opposite direction. The distribution of the ion concentration, however, greatly changes if the fluid flow is taken into account. The ion concentration around the anode and the rate of the electrochemical reaction that occurs at the anode surface are reduced by the fluid flow. The proposed computational framework offers a valuable basis for future research and development in the field of scrap-metal recycling technology.

Recycling precious elements from the electronic waste could be an environmental friendly way to avoid likely ecological damages caused by leaching of heavy metals and toxic elements as well as an economically attractive option to recover valuable materials that would otherwise be wasted. This research assessed the environmental and economic performance of recovering nine metal elements (aluminum (Al), copper (Cu), gold (Au), lead (Pb), nickel (Ni), silver (Ag), tin (Sn), zinc (Zn), and iron (Fe)) and two non-metal materials (resin and glass-fiber) from the waste printed circuit boards (PCBs), one of the vital components of electronic-waste (e-waste). SimaPro software was used to assess the environmental performance of recycling waste PCBs. Data were collected from recycling plants in Taichung City, Taiwan, and Eco-invent database was also used in the study. The impacts of metal recycling from PCBs were compared with the impacts caused by the mining of respective metals from their natural ores. Among the analyzed elements, only the recovery of Au from waste PCBs proved to have less environmental impacts than the mining from the natural ore. Among 16 environmental impact categories (ILCD midpoint 2011+ method of impact analysis) considered in the present study, cancer and non-cancer human toxicity were the most affected categories followed by minerals, fossils, and resource extraction. However, the economic analysis showed that the recycling of all elements from waste PCBs had a net positive benefit. When considering both the environment and economic performance, the recycling of Au proved to be a beneficial option.

The battery powder (anodic and cathodic mass) manually separated from spent Li-ion batteries used in laptops was subjected to acidic reductive leaching to recover the Co, Li, and Ni contained in it. In the laboratory experiments, 1.5 M sulfuric acid was used as the leaching agent and the reducing agents were 30% H2O2 solution or/and glutaric acid. Glutaric acid is a potential new reducing agent in the leaching process of spent lithium-ion batteries (LIBs). The influence of the type of the used reducer on obtained recovery degrees of Co, Li, and Ni as well as the synergism of the two tested reducing compounds were analyzed. As a result, it was determined that it is possible to efficiently hydrometallurgically separate Co, Li, and Ni from battery powder into solutions. The highest recovery degrees of the investigated metals (Co: 87.85%, Li: 99.91%, Ni: 91.46%) were obtained for samples where two reducers, perhydrol and glutaric acid, were added, thus confirming the assumed synergic action of H2O2 and C5H8O4 in a given reaction environment.

Phytomining has attracted widespread attention as a technique for harvesting &ldquo, bio-ore.&rdquo, This technology has potential applications in the metal and minerals industry for low-grade metal and mineral mining as well as metal recycling from polluted soil. The hotspots and future trends of this technology deserve in-depth exploration. This paper presents a systematic review of the phytomining research area through the scientometrics method based on the citation data collected from the Web of Science Core Collection (WoSCC). The results show that the earliest phytomining-related research was published in 1997. Between 1997 and 2019, 232 publications were published in 109 journals. Plant and Soil, the International Journal of Phytoremediation, and the Journal of Geochemical Exploration were the top three most prolific journals and accounted for 18.1% of these publications. Guillaume Echevarria, J.L. Morel, and Antony Van der Ent were the top three most prolific authors, and their work accounted for 40.1% of these publications. The cluster results of document co-citation analysis revealed that the hotspots in phytomining research area mainly includes &ldquo, nickel accumulation,&rdquo, &ldquo, heavy metal uptake,&rdquo, mining site,&rdquo, heavy metal,&rdquo, hyperaccumulation yield,&rdquo, growth effect,&rdquo, and &ldquo, alternative method.&rdquo, Keyword burst detection results find that the hot topics have changed over time from &ldquo, phytomining&rdquo, to &ldquo, agromining&rdquo, from &ldquo, contaminated soil&rdquo, serpentine soil&rdquo, and from &ldquo, mechanism&rdquo, phytomining process&rdquo, commercial phytoextraction.&rdquo, This study describes the intellectual landscape of research and provides future research directions for phytomining research so that researchers can identify future research topics and partners.

Anyang, the last capital of the Chinese Shang dynasty, became one of the largest metal consumers in Eurasia during the second millennium BCE. However, it remains unclear how Anyang people managed to sustain such a large supply of metal. By considering the chemical analysis of bronze objects within archaeological contexts, this paper shows that the casting and circulation of metal at Anyang was effectively governed by social hierarchy. Objects belonging to the high elites such as Fuhao, particularly the bronze ritual vessels, were made by carefully controlled alloying practice (primary) using very pure copper, whereas the lower elites only had access to bronzes made by secondary alloying practice and copper with more impurities. Such contrasts allow scholars to identify those objects which are less likely to have been made by mixing and recycling, which has very important implications for the chemical and isotopic determination of provenance for future studies.

This work aims to perform a comparative study of two mechanical processes for the recycling of metals from coaxial cables (aluminium and copper-clad steel): Process I - comminution, sieving and electrostatic separation; and Process II - comminution, magnetic separation and electrostatic separation. Characterization techniques were performed on the cables to discover their composition. The parameters evaluated of electrostatic separation were: roll speed (

Submerged plasma slag fuming technology is a process intensification of the traditional (coal-fired) slag fuming technology. A general dynamic model of the plasma-driven slag fuming process has been developed in FactSage 7.0 based on Metallo Belgium’s industrial scale submerged plasma slag fuming furnace. This model describes the chemical reactions, phase equilibria and heat transfer in each sub-unit operation, and the heat and mass transfer between the subsequent sub-unit operations of the slag fuming process. The model was validated on several process batches. Upon assessing the simulation results, a deviation was found from the industrial process, which can be explained using kinetic factors.

In this paper, a sustainable process to recover valuable metals from spent lithium ion batteries (LIBs) in sulfuric acid using ammonium chloride as reductant was proposed and studied. Being easily reused, ammonium chloride is found to be efficient and posing minor environmental impacts during the overall process. By investigating the effects of a wide range of parameters, e.g., H2SO4 concentration, NH4Cl concentration, temperature, leaching time, and solid-to-liquid mass ratio, the leaching behaviour of Li, Ni, Co, and Mn was systematically investigated. And the leaching mechanism and kinetics were determined by mineralogically characterization of residues at various reaction times and by fitting using different kinetic models. With this research, it is possible to provide a win-win solution to improve the recycling effectiveness of spent LIBs by using waste salt that is easily reused as the reductant.

The article presents the results of interpretation of a parts of a copper alloy bowls from the 10th-13th centuries. The vessels might have been originally used for liturgical ceremonies. We know a lot of bowls fragments from Europe that have been reworked as linings, ferrules or rivets. In all these examples we are dealing with metal recycling.