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We explored a novel design-for-recycling method for encapsulated printed electronics in an injection-molded package that improves disassembly at End-of-Life (EoL). To this end, a non-adhering disassembly layer (NADL) was applied onto the printed circuitry and light-emitting diodes prior to injection molding. Surprisingly, the devices with a disassembly layer remained fully functional after injection molding, despite exposure to high shear forces and elevated temperatures. Facilitating the disassembly of an encapsulated electronic device using a weak link in the adhesion strength of the overmolded encapsulant invokes a contradiction: the possibility to remove the injected plastic from any underlying coating goes against the requirement of high adhesion over the entire surface area for structural strength and integrity during the harsh conditions expected by industry. To achieve balance between disassemblability and reliability, the adhesion strength of the overmolded encapsulant was tuned using vias in the coating design. To the author's best knowledge, this is the first time design-for-recycling principles were successfully applied to such in-mold structural electronics devices. Accelerated lifetime tests at 85 °C/85% relative humidity for 1000 consecutive hours were conducted to study the reliability of devices realized with this design-for-recycling method. Mechanical disassembly of molded devices proceeded uniformly along the intended interface of NADL with molded polycarbonate resin and exposed the printed Ag and surface-mounted components, thereby demonstrating the possibility to perform subsequent and dedicated recycling on plastics and metals separately. • Dismantlable printed electronics; design-for-recycling method using non-adhering dismantling layers. • Adhesion of injection-molded polycarbonate made tunable by coating design. • Trade-off between recyclability and reliability; promising outcome for water-based non-adhering dismantling layers. [ABSTRACT FROM AUTHOR]

The decomposition of carbon dioxide (CO 2) is a potential negative carbon technology, and an effective way to achieve carbon recycling by converting CO 2 into high value-added chemicals. However, the CO 2 conversion usually requires harsh conditions, complex processes, and high energy consumption, which seriously limit its application and development. Here, we reported a new strategy for direct decomposition and utilization of CO 2 under mild conditions based on liquid metals, in which the CO 2 was transformed into carbon, corresponding efficiency is approximately 1.125 ml/(g·h). While the oxygen reacted with liquid metals to form Ga 2 O 3. Furthermore, the oxide by-products can be reduced to the liquid metals using the hydrogen at 800 °C for 10.0 h, which generated from water splitting by solar-driven, whereas 34.33% of liquid metals restore their original properties and can be utilized for further recycling. This provided a novel approach to the decomposition and renewable recycling of CO 2. Liquid metals with high surface activity were used as a platform for CO 2 renewable recycling decomposition at room temperature. In which, the carbon atoms in CO 2 are transformed into carbon materials, while the oxygen atoms react with liquid metals to form the oxides. Furthermore, the oxides can be reverse converted into liquid metals for recycling by solar-driven. [Display omitted] • The liquid phase structure of eGaIn at room temperature endows them with a unique and excellent surface activity. • The CO 2 can be spontaneously and instantaneously decomposed into carbon materials by liquid metals at room temperature. • The oxide byproducts were reduced to liquid metals using the hydrogen generated from water splitting by solar-driven and utilized for further recycling. • This finding has provided a versatile, tunable, renewable and recyclable method for the decomposition of CO 2. [ABSTRACT FROM AUTHOR]

Electronic waste remains a pressing global environmental concern. Addressing the proper treatment and recycling of waste printed circuit boards (WPCBs) is imperative to mitigate environmental pollution and prevent the loss of valuable resources. In this study, a comparative analysis of acidic and alkaline leaching processes for recovering base metals (Cu, Sn, Zn, and Ni) from WPCBs was conducted by process simulation (using HSC software). Life cycle inventories were compiled accordingly. Furthermore, by incorporating an alternative method for precious metal recovery, the life cycles (using openLCA software) of both processes for recovering all metals were examined. The results revealed that while the acidic leaching process showed higher recoveries for base metals and advantages in terms of lower electricity consumption and wastewater generation, it also exhibited a more pronounced environmental impact due to the chemical input in the HNO 3 leaching process. Conversely, the alkaline leaching process utilized fewer chemicals, generated less solid waste and off-gases, resulting in a lower overall environmental impact. For recycling 1 t of WPCBs, the acidic leaching process achieved recoveries of 92% for tin, 99% for copper, 79% for zinc, and 94% for nickel, whereas the alkaline leaching process yielded recoveries of 96%, 93%, 78%, and 74% for the corresponding metals. Notably, the alkaline leaching process demonstrated a lower global warming potential of 11,395 kg CO 2 eq, compared to the 12,459 kg CO 2 eq associated with the acidic leaching process. In the evaluation of the alkaline leaching process, most environmental impacts were found to be lower than for virgin production. As a result, while the acidic leaching process is indeed more efficient in metal recycling, the alkaline leaching process emerges as a stronger contender in terms of environmental sustainability, with great potential for further technical improvements. [Display omitted] • Two processes for recycling WPCBs were designed and modeled. • The environmental impacts of WPCBs recycling were studied. • Accurate inventory analysis was conducted based on process simulation. • The acidic leaching process demonstrated high metal recovery efficiency. • The alkaline leaching process promises sustainable and cleaner WPCB recycling. [ABSTRACT FROM AUTHOR]

Traditional recycling technology for spent lithium-ion batteries faces the issue of low Li recovery due to the considerable Li loss during leaching and further purification operations. To improve the Li recovery, high-pressure acid leaching using H 2 SO 4 for Li preferential liberation and the subsequent purification were systematically investigated. Experimental results showed that 97.6% of Li was preferentially leached with about 2% of Ni, Co, and Mn co-leached, and a leaching solution with a Li+ concentration of 21.46 g/L was obtained. Further characterization indicated that most of Li was first liberated and exchanged by the proton (H+), then the high reaction temperature induced the hydrolysis of the co-leached Ni2+, Co2+, and Mn2+ and generated extra H+ prompted a deeper liberation of Li from the undissolved NCM structures. Additionally, the high-purity Li 2 CO 3 was achieved via a synergistic extraction by D2EHPA and 4PC for the deep removal and recovery of co-leached Ni/Co/Mn followed by carbonation. Compared with the traditional end-Li-recovery method, the proposed method possesses the advantages of a short Li extraction process, high recovery, and low cost. Moreover, the preferential leaching of Li provided an opportunity for a novel hydrometallurgical process to recover spent lithium-ion batteries that consists of Li preliminary leaching, Ni–Co–Mn material leaching, precipitation of Fe/Al, and selective extraction of F, Ni, Co, and Mn was not separated that shorten the flowsheet in this process, dramatically reduced reagent consumption and wastewater generation. [Display omitted] • Preferentially extraction of Li with H 2 SO 4 was achieved by pressure leaching. • Hydrolysis of NCM compounds followed by H+/Li+ exchange reinforce Li liberation. • Selective removal of NCM impurities in leaching solution by D2EHPA/4 PC extraction. • A novel approach to recover valuable metals from spent LIBs was provided. [ABSTRACT FROM AUTHOR]

The efficient and clean recycling of spent lithium-ion batteries (LIBs) is essential for resource conservation and environmental protection. This work proposes a facile and clean process for recovering of valuable metals based on microwave-assisted hydrogen reduction of spent cathode materials followed by grind-leaching and magnetic separation. After hydrogen reduction, the spent cathode material was transformed into water-soluble LiOH, Ni–Co alloy and MnO, wherein LiOH was preferentially dissolved by grind-leaching, while Ni–Co alloy was recycled by magnetic separation. Compared with the traditional carbothermal reduction, lithium was converted into LiOH instead of Li 2 CO 3 , and the Li leaching efficiency was significantly improved. Ni–Co alloy can be separated with MnO via simple magnetic separation without acid leaching. Effects of roasting (roasting temperature and time) and grind-leaching (grinding time and liquid-to-solid ratio) parameters on the recoveries of Li, Ni, Co and Mn were investigated. Under the conditions of roasting temperature of 973 K, roasting time of 60 min, grinding time of 30 min and liquid-to-solid ratio of 5 mL/g, the grind-leaching efficiency of Li was 98.17%. Ni and Co were enriched in the magnetic material with recoveries of 99.71% and 98.52%, respectively. Moreover, the coupling mechanism between Li dissolution and particle dissociation during the grind-leaching process was revealed. [ABSTRACT FROM AUTHOR]

The recycling of valuable metals from circulating fluidized bed (CFB)-derived high-alumina fly ash (HAFA) paves the way for ash utilization with high economic benefits. However, obtaining an ideal extraction ratio for metals using a single acid treatment under moderate conditions is difficult. A moderate acid–alkali–based alternate method was used in this study to extract aluminum (Al) from CFB-derived HAFA. The dissolution behavior of lithium (Li), gallium (Ga), and rare earth elements (REY) was investigated. The characteristics of leaching residues were studied by XRD, 27Al and 29Si MAS NMR, BET, and SEM-EDS. Results show that Al in the units with low degree of polymerization distributed on the particle surface was preferentially dissolved in the HCl solution. HCl could not penetrate the particle interior and thus greatly limited the improvement of the Al extraction ratio. NaOH solution effectively removed SiO 2 that accumulated on the particle surface and broke the Si–O–Al units in the residues. The exposed and liberated Al was further extracted with the HCl solution. Finally, 78% of Al 2 O 3 , 80% of Li, 72% of Ga, and 55% of REY in the ash were extracted with the HCl solution. Moreover, 63% of SiO 2 in the ash was dissolved in the NaOH solution. The acid leaching residue presented abundant mesopores and a high specific surface area of 205 m2/g. The findings imply that the proposed method that combines the extraction of valuable metals and the preparation of mesoporous materials provides a new way to utilize CFB-derived HAFA. Image 1 • Most of valuable metals in CFB fly ash were extracted under moderate conditions. • Separation mechanism of aluminum and silicon in the fly ash was discussed. • Final residue has abundant mesopores and a high specific surface area of 205. m2/g. • Metal extraction and preparation of mesoporous material were combined in a process. • Proposed comprehensive utilization method suitable for CFB fly ash was discussed. [ABSTRACT FROM AUTHOR]

Due to the rapid expanding of plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs) and electric vehicles (EVs), the projectfed demand for lithium-ion batteries (LIBs) is huge and might result in supply risks for natural lithium-containing reserves. After the service life, spent LIBs continuously accumulate in the market, and they are excellent secondary resources for lithium recovery. To alleviate resource shortage and to decrease potential environmental pollution caused by improper solid waste disposal, recycling of spent LIBs is motivated world widely in recent years. Previous studies have usually focused on the recovery of cobalt and nickel, which create high economic benefit. Recovery of lithium, however, has not been highlighted. In this article, state-of-the-art on spent LIBs recycling is discussed with emphasis on lithium recovery. In addition to understanding underlying mechanisms and physiochemistry features of various recycling methods, the possibility for industrial realization of each method is also evaluated. The complex processing steps limit the industrial implementation of hydrometallurgy-dominant methods, which usually reclaim lithium in the last step, resulting in a poor recovery efficiency of lithium. The pyrometallurgy-dominant approach is readily to scale up but lithium is lost in the slag phase. Therefore, the mild recycling (cleaner production) methods are recommended for future study since they take advantages of traditional pyrometallurgy and hydrometallurgy, and could decrease treatment temperature as well as acid/alkaline usage. Image 1 • More efforts are appealed to recycle electrolyte with respect to lithium recovery. • Lithium is usually the last metal to recycle in hydrometallurgical methods. • Pyrometallurgical methods should decrease lithium lost and energy consumption. • External field assisted pyro combined with hydro methods are promising. [ABSTRACT FROM AUTHOR]

Present work addresses Co(II) extraction from chloride medium using toluene diluted Cyphos IL 102 as an innovative extractant for the recovery of cobalt. Effect of various parameters has been examined. Co(II) is transferred into the organic phase as [P 66614 +] 2 [CoCl 4 2−] which can be efficiently stripped by 0.05 mol L−1 HCl. Loading capacity and recyclability have been assessed. Temperature effect confirmed that the extraction of Co(II) is endothermic in nature. Studies were further extended to recover cobalt, manganese and lithium from waste Li-ion batteries containing 2.915 g L−1, 0.576 g L−1, 3.370 g L−1, 0.407 g L−1, 0.014 g L−1, 0.033 g L−1, 0.019 g L−1 of cobalt, lithium, manganese, nickel, aluminium, iron and copper, respectively. The influence of the concentration of Cyphos IL 102 to extract cobalt from leach liquor has been investigated. The McCabe-Thiele plot suggested two theoretical stages of counter current extraction at A/O 1/1 with Cyphos IL 102 (0.2 mol L−1) for the quantitative extraction of Co(II) with negligible extraction of nickel and lithium. A stripping efficiency of around 99.9% for Co(II) was obtained using 0.05 mol L−1 HCl in a single stage at O/A 1/1. Cobalt is recovered as cobalt oxide from the loaded organic phase. Manganese and lithium were also recovered from leach liquor as MnO 2 and Li 2 CO 3 using the precipitation method. All the recovered products were identified using XRD, EDX as well as FE-SEM techniques. Image 1 • Cyphos IL102 explored for the first time for recycling of Co from waste Li battery. • Extraction of Co via anion exchange mechanism involving CoCl 4 2− species. • Extractant is recyclable and no phase modifier required. • 98.6% Co recovered as pure Co 3 O 4 by solvent extraction. • 99.9% Mn and 99.6% Li recovered by precipitation as MnO 2 and Li 2 CO 3. [ABSTRACT FROM AUTHOR]

With the rapid increase of new energy industry, the shortage of critical metals for new energy industry, such as Ni, Co, V, and Pt, has received global attention. The hazardous spent catalysts from traditional energy industry contain a series of critical metals, which should be safe disposal and even value-added utilized. However, the recovery of critical metals from these valuable wastes has not been well accepted. In this review, the characteristics and recycling necessity of spent catalysts are described in the start section, and then the current progress on stepwise recycling techniques of three typical spent catalysts are summarized, which are petroleum refining hydrogenation catalysts, platinum group metals catalysts and selective catalytic reduction catalysts. The regeneration and value-added utilization examples of these catalysts have been discussed and prospected. An overview of the advantage and disadvantage features of these techniques is presented, associating with the environmental assessment. At the end of the paper, the evolutions of metal elements and species of the recycling process are emphasized for rational designs and considerations from the mechanism of molecular level. The further perspective on the more practical value-added utilization is highlighted. This review set up a closed-loop conversion bridge from traditional energy wastes to new energy materials. Critical metal resource recycling of spent catalysts is a bridge connecting the traditional energy industry and the new energy industry. [Display omitted] • Current recycling techniques and necessities of hazardous spent catalysts are reviewed and summarized. • The spent HDS catalysts, PGMs catalysts and SCR catalysts are selected as three typical hazardous catalysts. • The value-added utilization has been highlighted as future directions of recycling process. • The evolutions of metal elements and present species in aqueous solutions are described. [ABSTRACT FROM AUTHOR]

Due to the high economic and environmental benefits, researchers have considered recycling metal chips, especially for the more valuable alloys of copper, brass, aluminium, etc. Several methods have been used including casting and solid-state techniques for recycling the metal chips, wasted annually in large quantities by machining processes. This work examines the sustainability of the Friction Stir Extrusion (FSE) technique, as one of the most recently developed methods for recycling metal chips, comparing it to six different casting methods. Four sustainability indicators of economic, environmental, social, and mechanical performance are calculated and compared for the FSE and casting methods, using a multi-dimensional sustainability methodology. In terms of environmental, social, and mechanical indicators, the FSE method gained significantly the highest levels and in overall sustainability, it achieved the best score of 0.78, while the worst casting technique for recycling was 0.514. However, economically, the FSE has not yet gained a foothold in the industry and needs more attention from manufacturers, environmentally friendly craftsmen, and recycling firms side. Despite the higher investment required for the FSE process (compared to conventional casting techniques) and its lower economic feasibility, the FSE is expected to become more economically viable in the future by further research and development in its tools. [ABSTRACT FROM AUTHOR]

Existing schemes of solid waste handling have been improved implementing advanced systems for recovery and reuse of various materials. Nowadays, the ‘zero waste’ concept is becoming more topical through the reduction of disposed waste. Recovery of metals, nutrients and other materials that can be returned to the material cycles still remain as a challenge for future. Landfill mining (LFM) is one of the approaches that can deal with former dumpsites, and derived materials may become important for circular economy within the concept ‘beyond the zero waste’. Perspectives of material recovery can include recycling of critical industrial metals, including rare earth elements (REEs). The LFM projects performed in the Baltic Region along with a conventional source separation of iron-scrap, plastics etc. have shown that the potential of fine-grained fractions (including clay and colloidal matter) of excavated waste have considerably large amounts of potentially valuable metals and distinct REEs. In this paper analytical screening studies are discussed extending the understanding of element content in fine fraction of waste derived from excavated, separated and screened waste in a perspective of circular economy. Technological feasibility was evaluated by using modified sequential extraction technique where easy extractable amount of metals can be estimated. Results revealed that considerable concentrations of Mn (418–823 mg/kg), Ni (41–84 mg/kg), Co (10.7–19.3 mg/kg) and Cd (1.0–3.0 mg/kg) were detected in fine fraction (<10 mm) of waste sampled from Högbytorp landfill, while Cr (49–518 mg/kg) and Pb (30–264 mg/kg) were found in fine fraction (<10 mm) of waste from Torma landfill revealing wide heterogeneity of tested samples. Waste should become a utilizable resource closing the loop of anthropogenic material cycle as the hidden potential of valuable materials in dumps is considerable. [ABSTRACT FROM AUTHOR]

Recovering metal values from spent Lithium ion batteries (LIBs) enjoys a great significance in environmental protection and sustainable development of resources. But the application of mixed-type cathode materials in PHEV and EV with high content of manganese brings new challenges for spent LIBs recycling. In this study, a facile approach for directly regenerating Mn-rich cathode material from mixed-type spent cathode materials was developed. The spent cathode materials were firstly tested by X-Ray Diffraction (XRD) and X-ray fluorescence (XRF) and then leached in H 2 SO 4 +H 2 O 2 system. The spherical Mn-rich cathode material was directly regenerated from leaching liquor through a facile co-precipitation method followed by solid-phase sintering. The regenerative cathode material was measured by XRD, scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy system (EDXS), inductively coupled plasma atomic emission spectrometry (ICP), laser particle size analyzer and electrochemical tests. According to the results, pure cathode material exhibits a uniform particle size distribution and a layered structure. Furthermore, the regenerative cathode material with high working voltage (>4.5 V) possesses excellent discharge capacity. Cleaner production analysis indicates that whole process can effectively reduce waste residue and water, and helps turn the solid waste into resource. Meanwhile, compared to traditional methods, the proposed process can simplify the recovery process, obtain high value added Mn-rich cathode material and maximize the recovery of manganese in the mixed-type spent cathode materials. [ABSTRACT FROM AUTHOR]

The high demand of rare earth elements (REEs) in electronics industry and their high supply risk owing to the dependence on limited source countries have increased the interest towards Waste Electrical and Electronic Equipment (WEEE) as a potential secondary source of these elements, identified as critical metals. Although REEs are present in a wide range of high-tech products in relative low concentrations, the recycling of critical metals from WEEE is regarded as an important opportunity for promoting the conservation of primary resources and preventing waste production. However, the existing systems for WEEE collection and treatment mainly focus on the recovery of base and precious metals while the fate of REEs has not been addressed yet. To this end, the present study aims at evaluating the substance flows of critical metals in WEEE mechanical pre-treatments as these processes, preceding the metallurgical treatments of refining, determine the amount of metals entering the further recovery chain. The separation efficiency of a full scale mechanical process, including a sequential shredding and selection treatment of small WEEE, was investigated assessing the mass balance of both base metals and special metals as well as the quality of the output products. The mass flow analysis revealed that after pre-treatments only a third of precious metals entering the treatment process was conveyed to the target output destined to further recovery and less than 2% of REEs was concentrated in the potentially recyclable metallic fractions, while approximately 80% of these elements was distributed in the dust stream actually destined to landfill. Furthermore, the study pointed out that the fine fraction of the metallic outputs from the sorting process is characterized by a major degree of purity, indicating that both the dust stream and the fine grain fraction could be regarded as secondary sources for the recovery of valuable and critical metals from WEEE. [ABSTRACT FROM AUTHOR]

Silicon kerf waste can be used as a secondary resource for the recovery of high purity silicon for solar cells production. Boron is amongst the most deleterious impurities in silicon and its concentration should be strictly controlled. Slag treatment is considered an effective method to extract impurities, especially boron, from silicon kerf. The study investigated the feasibility and optimization of a process for producing high-purity silicon from sawing waste by slag treatment. The slag system studied was Na 2 O-SiO 2 and the effects of holding time, slag composition, and slag:kerf ratio on boron distribution were investigated. The optimum conditions for refining of silicon kerf at 1923 K were found to be a slag of 65 wt.% Na 2 O−35 wt.% SiO 2 and treatment for 30 min. This resulted in reduction of boron concentration in silicon from 8.6 to 1.0 ppmw, corresponding to a removal efficiency of 88%. Investigation of the boron transfer mechanism indicated that mass transfer of boron in slag is likely the rate controlling step of the overall process. The mass transfer coefficients for boron in silicon and slag were 3.6 × 10 −6  cm⋅s −1 and 5.8 × 10 −6  cm s −1 , respectively. [ABSTRACT FROM AUTHOR]

End-of-life light emitting diode (LED) associated with its electronic product is a new type of electronic waste (E-waste) and contains considerable amounts of valuable and hazardous metals. Although the quantity of a single LED is small, the total number of end-of-life LEDs is extremely significant that requires proper management and recycling from both resource and environmental points of view. Particularly, metals recycling from electronic waste has been considered as a preferred option to ensure sustainable supply of critical materials. In this research, it demonstrates a methodology to evaluate the criticality and recyclability of various types of end-of-life LEDs. Two factors, i.e. the resource index and technology index, were introduced into identifying the criticality of different types of waste LEDs, which indicates the potentials for effective metals recycling. Furthermore, combined statistical entropy and grading, the recyclability is assessed to identify the viability for metals recycling from different types of end-of-life LEDs. The results of the proposed evaluation methodology suggest that green/high luminous intensity LED exhibits significant potential for metal recycling and blue/high luminous intensity LED exhibits the lowest recycling difficulty. The aims of the research are expected to assist manufacturers and policy-makers improving the recycling effectiveness of waste LEDs especially in the metals recycling stage and developing effective waste management systems and strategies in the end-of-life stage. [ABSTRACT FROM AUTHOR]

Rare earth elements recycling has been proposed to alleviate supply risks and market volatility. In this context, the potential of a new recycling pathway, namely plasma mass separation, is uncovered through the example of nedodymium - iron - boron magnets recycling. Plasma mass separation is shown to address some of the shortcomings of existing rare earth elements recycling pathways, in particular detrimental environmental effects. A simplified mass separation model suggests that plasma separation performances could compare favourably with existing recycling options. In addition, simple energetic considerations of plasma processing suggest that the cost of these techniques may not be prohibitive, particularly considering that energy costs from solar may become significantly cheaper. Further investigation and experimental demonstration of plasma separation techniques should permit asserting the potential of these techniques against other recycling techniques currently under development. [ABSTRACT FROM AUTHOR]

The present study is the first report on the bioleaching of indium (In) from discarded liquid crystal displays (LCDs) using adapted Acidithiobacillus thiooxidans . The adaptation of bacteria to the LCDs powder began with 1% (w/v) and continued up to 4% (w/v). Response surface methodology (RSM) was used to evaluate the effects of initial pH, pulp density, and initial sulfur concentration and optimize their values in order to maximize In and Sr recovery. Under optimum conditions of an initial pH of 2.6, pulp density of 1.6% (w/v) and initial sulfur concentration of 8.6 (g/l), 100% of In and 10% of Sr were recovered. The rate-controlling step in this process was determined using the shrinking core model, which suggests that both diffusion and chemical reaction play an important role in the overall bioleaching process. Scanning electron microscopy (SEM) analysis demonstrated the effectiveness of bacterial activity in bioleaching. In addition, the results confirmed that bioleaching was more effective than chemical leaching. The bioleaching from discarded LCDs by A. thiooxidans is a promising technology that can decrease the environmental hazard of this waste. The bioleaching results of present study supplied a method for large-scale industrial purposes. [ABSTRACT FROM AUTHOR]

Recovery of valuable metals from spent lithium-ion battery (LIB) is of both environmental and economic importance. Acidic leaching usually encounters issues of low selectivity or slow kinetics with considerable secondary waste generation during further purification. In this research, a closed-loop process with improved leaching selectivity for recycling of spent LiNi x Co y Mn 1-x-y O 2 battery using weak acidic leachant was demonstrated. To obtain optimal conditions of the leaching process, the effects of acid concentration, solid to liquid (S/L) ratio, temperature and reductant content were systematically investigated. Almost all Co, Li, Mn and Ni could be effectively recovered into the solution while Al remained in the residue as metallic form, after one-step leaching. The role of reductant during leaching was further evaluated which was found to be critical for the leaching kinetics. It is clear that the addition of reductant could alter the rate-controlling step of leaching from the ion diffusion in the residue layer to the surface chemical reactions. With high selectivity against impurities, this research proposed and verified a process to recover high purity Li 2 CO 3 from the cathode scrap of LIBs, and more than 90% of the global recovery rate of valuable metals can be achieved. [ABSTRACT FROM AUTHOR]

A cleaning process, including the steps of alkaline leaching, precipitation of lead and stabilization of arsenic, was proposed for separation of arsenic from lead anode slime generated in lead smelter before valuable metals recycling. The anode slime was first leached by NaOH solution at oxygen pressure, and the optimum conditions were obtained as follows: α (NaOH) = 1.2 (where α represents excess coefficient), temperature 160 °C, liquid-solid ratio 5:1, oxygen partial pressure 1.2 MPa, where the leaching rates of arsenic and lead reached 95.65% and 0.96%. Second, the leaching solution underwent oxidative precipitation for lead separation in the form of PbO 2 using sodium persulfate as oxidizing agent. Under the optimum conditions, the precipitation rate of lead was 94.53%. Then, the sodium arsenate was crystallized from the latter precipitation solution. Finally, the re-dissolving arsenic was solidified by the atmospheric oxidation method to form scorodite crystal. A suitable pH range for scorodite formation was below pH 6.0, where the highest precipitation rate of As was 88.48%. However, for solution pH higher than 6.0, the precipitates were very fine and showed inferior crystallinity as well as being unsafe for long-term stockpiling. It is suggest that this process has potential application for dearsenification from all arsenic-rich anode slime. [ABSTRACT FROM AUTHOR]

Dust is an indispensable byproduct in the physical-mechanical recycling process of waste printed circuit boards. It is in urgent need for recycling valuable materials from dust because of high economic value and serious pollution. In this study, a novel technology of vibrated gas-solid fluidized bed was proposed to recover metals from dust with a size fraction of −0.5 mm. Firstly, the mineralogical properties were analyzed by advanced analysis technologies, and then the triboelectric separation was applied to remove glass fibers from dust to eliminate the effect of agglomeration that was caused by glass fibers in the process of density-segregation. The results demonstrated that the major metal elements were Fe, Cu, Mn, Zn and Mg, and the content of metals accounted for 18.865 wt.% in −0.5 mm size fraction of dust. The metal content increased to 21.852 wt.% after removing glass fibers. The metal recovery rate was up to 78.77%, which demonstrated that the vibrated gas-solid fluidized bed had obvious recovery efficiency for metals from dust. This research work may provide an alternative approach for industrial recycling WPCBs dust, and reduce the secondary waste generated in PCBs recycling. [ABSTRACT FROM AUTHOR]

Recycling spent lithium-ion batteries (LIBs) has been a global hot spot due to the increasing scrap amount and enriching valuable resources. Acid leaching is the crucial step of hydrometallurgy recycling metals from spent LIB. However, the uncontrollable components cause many trials for obtaining the optimal leaching parameters, which increases the recycling cost and environmental risk. Herein, this study applied machine learning (ML) to guide metal leaching from spent LIBs and could quickly obtain the leaching results without the vast leaching experiments. After referring to the relative studies between 2005 and 2022, a total of 17,588 data points were collected as the dataset for ML. The process parameter influences of metal leaching were comprehensively revealed through the ML analysis of 20 input features and 4 output metal leaching efficiency. Then, a convenient graphical user interface (GUI) was developed to guide efficient metal leaching from spent LIBs, only measuring the particle size and composition of waste and avoiding extensive leaching experiments. Finally, some experiments verified the GUI reliability. This study can significantly reduce the experiment cost and environmental risk, which trailblazes the smart and efficient recycling of spent LIBs. [Display omitted] • Machine learning is used to guide metal leaching from spent lithium-ion batteries. • The parameter influences on metal leaching are deeply revealed by machine learning. • The developed graphical user interface can help get the leaching parameters quickly. • This study opens up new avenues for the smart recycling of spent batteries. [ABSTRACT FROM AUTHOR]

Alkaline slurry electrolysis has been verified as an effective method for metal recovery from waste printed circuit boards (WPCBs). However, the electrolyte that remains after slurry electrolysis contains high concentrations of metal, which can cause pollution without suitable treatment. Most importantly, the metals in the electrolyte are not completely recovered, resulting in wasted resources and increased costs. Here, the feasibility of circulating this electrolyte and its effect on copper recovery, current efficiency, and purity, is discussed. We also describe in detail the migration and transformation of copper and other metals, such as nickel, zinc, and lead, during the preparation of high-purity cathode copper from mobile phone WPCBs (WPCB-MPs) using an ammonia-ammonium chloride slurry electrolysis system. Experimental results from 19 cycles of electrolyte reuse show that copper is mainly distributed in the cathode products, whereas other metals are mainly distributed in the electrolyte and anode residues. With an increase in the number of cycles, the concentration of other metals in the electrolyte gradually increased, showing metal enrichment. The current efficiency fluctuates but is usually >90%. In addition, the copper recovery rate and purity were essentially unaffected, being >99% and >99.9% for all 20 runs, respectively, and all the cathode copper foils were easily peeled off. This study demonstrated that electrolytes can be reused for metal recycling from WPCB-MPs by alkaline slurry electrolysis without decreasing Cu purity, Cu recovery rate, and current efficiency. Thus, this study provides a green and cost-effective process for recycling resources from e-waste. [ABSTRACT FROM AUTHOR]

In this study, an effective and novel nanocomposite (Fe 3 O 4 @TAS) was prepared and applied for the removal of Cd(II), Cr(III) and Co(II) from liquid medium. The mechanism for the adsorption was elucidated by investigating the adsorption kinetics, isotherms and thermodynamics, thoroughly. The maximum adsorption capacities as found by the Langmuir model were 286, 370 and 270 mg g −1 for Cd(II), Cr(III) and Co(II), respectively. The structure, size, porosity and magnetic property, of the prepared magnetic nanocomposite were investigated by FT-IR, XPS, SEM-EDX, BET, XRD, HRTEM and VSM analyses. The saturation magnetization and BET surface area for Fe 3 O 4 @TAS were 41.4 emu g −1 and 210.34 m 2 g −1 , respectively. Fe 3 O 4 @TAS was easily separated from aqueous solution using external magnet and it was regenerated by simple washing with 0.01 M HCl solution. The thermodynamic parameters showed that the involved process was spontaneous and exothermic. The findings inferred that Fe 3 O 4 @TAS had the efficiency in treating wastewater with coexisting metals such as Cd(II), Cr(III) and Co(II) metal ions. [ABSTRACT FROM AUTHOR]

The difficulties for selective metal recovery from electronic waste are induced by the high complexity of such waste stream and complicated purification procedures. In this research, an electrochemical stimulated method is demonstrated to selective recover copper from an industrially provided electronic waste. More specific, one-step selective copper recovery was achieved by combining electrochemical dissolution and deposition in ammonia-based electrolyte. In the process, copper instead of other impure metals from the electronic waste is selectively dissolved and electrochemically enhanced at the anode. On the other side of the cell, pure copper was electrodeposited at the cathode. The current efficiency was found to be significantly influenced by the applied current density if galvanostatic process was facilitated. Both temperature and copper concentration in the electrolyte were found to have positive effects on the current efficiency. In a well-controlled process, copper of 99.56 wt% purity can be obtained which can be further improved by preventing potential oxidation on the electrodeposited layer. This research provide a possibility for selective copper recovery in one-step by substantially decreasing the purification cost and simplifying copper recovery procedures from electronic waste. [ABSTRACT FROM AUTHOR]

Hydrometallurgy-based recycling processes for spent lithium-ion batteries (LIB) can be conducted under mild operating conditions while achieving a high metal recovery rate. However, due to the excessive use of chemicals during operation, issues associated with operating costs and pollution of disposed wastewater hinder large-scale application. The disposed wastewater contains highly concentrated ions that can be reutilized via electro-electrodialysis (EED). In addition, regenerated base can be utilized as a CO 2 absorbent, which produces soda ash that can be directly utilized for metal precipitation in the recycling process. Thus, this paper proposes a novel integrated system of wastewater EED and CO 2 capture for sustainable LIB recycling. This system includes selective metal recovery of cathode material, wastewater EED, and CO 2 capture and utilization. Based on the simulation results, system performance was evaluated considering the regenerated chemical concentration and its impact on the metal recovery rate. The complete regeneration of 2.04 M sulfuric acid and 1.09 M caustic soda solutions could be accomplished from the waste liquid. In recycling capacity of 50,000 ton/year, 0.33 kg of CO 2 could be captured per 1 kg of LCO cathode material, and 99% selective metal extraction could be accomplished during battery recycling using the regenerated chemicals. To clarify economic performance, the levelized cost of recycling was analyzed in different market scenarios for chemicals. The proposed system can accomplish full regeneration of wastewater via EED with a 21.90% lower levelized cost of recycling compared with the conventional system. The results of simulation and economic analysis demonstrate the potential performance of the proposed system in terms of sustainability and economic feasibility in current LIB recycling industry. [Display omitted] • Electro-electrodialysis and CO 2 capture and utilization integrated to recycle LIB. • Full regeneration of 2.04 M sulfuric acid and 1.09 M caustic soda was accomplished. • 0.33 kg/kg LCO of CO 2 was captured and 99% battery recycling was accomplished. • A solution for waste-free recycling of large-scale cathode material is proposed. [ABSTRACT FROM AUTHOR]

Huge amounts of Pb smelting residues were generally stored in landfills or unprocessed worldwide, and thus demand novel strategies to implement clean production. In this paper, we proposed a clean, efficient and economical hydrometallurgical route to recycle the toxic heavy metals including Zn, Pb and Cd from the Pb residue by the biodegradable low-molecular-weight organic acids (LMWOAs) and the cation exchange resin (CER, 001 × 7). The multi-objective leaching process of the three metals was optimized by combining saturated D-optimal design with desirability function simultaneously. The recovery rates of Zn, Pb and Cd were 88.72–96.36, 65.40–85.31 and 92.63–97.10% at the optimal conditions of 0.73–1.00 mol L−1 agent concentrations, 2.0–3.3 solution pH values and 71–120 min durations, respectively. Adsorption with CER from the resulting leachates recycled over 91.48% of the metal ions. The treated residues were almost completely decontaminated. Therefore, this research filled the gap of clean production route of hydrometallurgical recycling for metal resources from the low-grade slag. [Display omitted] • Citric, malic and acetic acids are promising extractants for metal leaching in Pb residue. • Saturated D-optimal design coupled with desirability function was first employed for multi-objective optimization. • Cation exchange resin (001 × 7) was an efficient adsorbent for the toxic metal ions. • Environmental risk of heavy metals significantly reduced by three organic acids leaching. [ABSTRACT FROM AUTHOR]

The growing use of lithium nickel manganese cobalt oxide (NCM) batteries has necessitated increased recovery of cathode materials for sustainable battery recycling given the limited metal source, and to mitigate the negative environmental impact of battery disposal. Acid leaching and the use of precipitants are essential for selective metal extraction in the recycling process. However, the excessive use of chemicals degrades the economic performance of the recycling process. In this study, we propose and simulate a novel lithium-ion battery (LIB) recycling system through sequential S O X , N O X , and C O 2 utilization of industrial flue gas in the following four processes: sulfuric acid and nitric acid regeneration from S O X , N O X , acid leaching of cathode materials, N a 2 C O 3 regeneration from sulfur and nitric-free flue gas, selective precipitation. In the sequential flue gas capture and utilization, the H 2 O 2 is used as a wet absorbent for both desulfurization and denitrification, and produces 3.3 M H 2 S O 4 and 7.18 M H N O 3. NaOH is used for C O 2 utilization, and 2.32 M of N a 2 C O 3 is produced. We expected that the sequential flue gas utilization reduced the acids and precipitant consumption in the battery recycling process, which was more advantageous than the conventional recycling process by 2.70%. • First attempt at applying SO x , NO x , and CO 2 capture and utilization (SCU, NCU, CCU) to the LIB recycling process. • 3.3 M, 7.18 M, and 2.32 M of H 2 SO 4 , HNO 3 , and Na 2 CO 3 are produced via the sequential flue gas utilization. • Sequential flue gas utilization accomplishes 96.43% metal recovery efficiency. • Proposed process was 2.70% more economical than the conventional process. [ABSTRACT FROM AUTHOR]

An up-to-date techno-economic assessment was conducted on CO 2 emissions reduction potential in the Japanese iron and steel industry for 2030. The following mitigation measures were investigated: (i) maximized installation of best available technologies (BAT scenario), (ii) increased use of coke substitutes in blast furnaces, and (iii) increased use of obsolete steel scrap. For measure (iii), this study assessed the obsolete scrap use in the integrated steelmaking (BF-BOF) route, rather than increasing steel production from the electric arc furnace (EAF) route. CO 2 capture and storage (CCS) was not considered due to large deployment uncertainty. The results showed that 20 Mt–CO 2 of emissions reductions, equivalent to 12% of the industry's total emissions in 2010, can be achieved in 2030 compared with a frozen technology scenario. More than 9 Mt–CO 2 reduction was attributable to the enhanced use of obsolete scrap in the BF-BOF route. Consequently, the industry's emissions reduce by about 7 Mt–CO 2 or 4% below 2010 levels. Almost all domestically recovered obsolete scrap can be fully consumed solely by increasing the scrap use in basic oxygen furnaces (BOF). Moreover, the increase in average copper concentration in the BF-BOF steel due to the increased obsolete scrap use was found unlikely to limit the production of high-quality steel products. In comparison with a scenario that only considered measure (i) and assuming a 15% real interest rate, CO 2 mitigation cost curves for 2030 showed that the CO 2 mitigation costs were below US$ 2010 20/t-CO 2 for measure (ii) and around US$ 2010 110/t-CO 2 for measure (iii). Compared to the marginal abatement costs calculated for 2030 to reduce Japan's GHG emissions by 20%–25% from 1990 levels (about US$ 2010 67–640/t-CO 2 ) reported in the literature, all three measures may become economically viable. The increased use of obsolete scrap in the BF-BOF route can become an interesting option for Japanese steelmakers to stimulate the steel scrap market and achieve economical global CO 2 emissions reductions while maintaining international competitiveness in the midterm future. [ABSTRACT FROM AUTHOR]

A Life Cycle Analysis of End-of-Life Computers was developed for management of computers discarded in Mexico for the year 2014 through LCA methodology (ISO 14044) and using specialized software named Umberto ® version 5.5.4 with database Ecoinvent 2.2. The modeling consisted in the current scenario in Mexico (10% recycling) versus four alternative scenarios: 0% recycling, 25% recycling, 35% recycling and elimination of open dump disposal considering experience in other countries and real possibilities of medium-term management. All practices of management and recycling are considered in the model with changes in the recycling rates and installed infrastructure for different alternatives proposals. On the other hand, the model included that dismantling operations are done mostly with manual labor; transportation, extraction and processing of printed wiring boards, including local process of transforming, heating and melting of materials and considering recycling in Asian countries with all the environmental burdens processes involving transoceanic transportation and metallurgy. The majority of non-precious metals recycling was considered to take place locally. A substantial benefit was identified for all recycling scenarios, particularly in the elimination of open dump disposal and the recycling of 35% of the stream and was found that there was a high impact on climate change and adverse toxic effects to health and natural environments for the practice of accumulating waste in sanitary landfills and dumpsites as well as by burning of materials (plastics and others) in open areas. The use of recycled materials versus virgin materials was also beneficial up to 10 times for reduction in global warming potential impact and up to 3 times reduction for human toxic potential. Public policies might be recommended in order to protect health and environment. As public policy recommendations, it is proposed reinforcement the national infrastructure to collect EoL computers- and transformation of materials into new commercial products, and as a starting point for the recycling of all generated materials, including plastics and printed wiring boards, but should also include the promotion of research for the transformation of plastic waste and the implementation of new technologies that can be adopted by the national recycling industry and create new regulations that result in the production or import of EoL computers and other electronics with low levels of toxic substances as their main components. Other public policies should include the legal prohibition of use of landfills and dumps for containment of EoL computers and other electrical and electronic equipment. [ABSTRACT FROM AUTHOR]

The modelling of metal flows provides a comprehensive picture of metal use in the economy and allows for effective investigation into barriers and enablers to increase the recycling rates. In the export-oriented economy, such as Australia, the modelling requires clearly distinguishing the cycles within and outside of a country, and needs an adequate metrics to assess the country's targets in “closing the material loop”. This article investigates Australian position in the global cycles of metals production and use, and assesses the potential for circularity of metals within the country based on data from 2002 onwards. The analysis shows that over the period from 2002 to 2011 the overall estimate of metals final consumption grew from 8.8 million tonnes to 12.3 million tonnes, or from 445 to 551 kg per person. Similarly, the amount of generated waste metal is estimated to have grown from approximately 5 million tonnes to 6 million tonnes, or 250–270 kg per person respectively. The amount of collected metal scrap grew from 3.3 Mt to 3.9 Mt, with the overall collection rates being relatively stable at about 70%. However, the domestic processing of collected scrap decreased significantly – from 67% in early 2000s to 41% in early 2010s, while the export of scrap increased accordingly. The current levels of waste metal generation, metal scrap collection, and domestic processing of metal scrap in Australia equal approximately 50%, 35%, and 15% of the country's metals final consumption respectively. [ABSTRACT FROM AUTHOR]

Urban mining has attracted increasing attention as a research topic, owing to the high growth rate, environmental issues, and market potential of waste generated in urban areas. Metal recovery from such waste has become increasingly important especially in accordance with the concept of metal criticality. This study develops a model by evaluating various types of urban waste in order to understand the criticality of these waste streams and determine their potential for metal recovery. Two factors, i.e. the resource index and technology index, are defined and assessed through a systematic review of data from the literature and industry. High values of the resource index indicate that the waste is important to the European Union (EU) economy and hence has significant potential for recycling as a resource. Furthermore, a high technology index indicates that the waste can be processed for metal recovery with less technology investment than that required for a waste that has a low technology index. However, a high environmental impact for the recovery of metals, indicates that processing of the waste is difficult and potentially has high impact on the environment. A case study of 11 waste streams from a local recycling company is performed, by using the correlation of these two indices. The results of the evaluation suggest that the information and communication technology (ICT) scrap and the rare-earth elements (REEs) containing end-of-life (EOL) products exhibit significant potential for metals recovery. The technical aspects governing the recovery of valuable metals from these two resources are further analysed and potential processing routes (flowsheets) can be suggested. Combined with both physical separation and metallurgical processing, the proposed evaluation methodology and the processing routes for targeted critical metals, are expected to contribute to the development of competitive recycling technologies. [ABSTRACT FROM AUTHOR]

Due to the recent trend towards increasing renewable energy production, a large proportion of this demand will be addressed by solar energy. This greater consumption of solar cells will inevitably result in an equally large amount of end-of-life material that should be recycled to recover the valuable metal components. In the present work, the dissolution of silver and aluminium from silicon solar cells was investigated using copper(II) chloride and iron(III) chloride as redox catalysts, dissolving up to 95% of the target metals within 10 min. A mixed hydro- and ionometallurgical approach was taken, with a 2-step selective leaching process. Initially, aluminium and other lower value metals are removed using iron(III) or aluminium(III) chloride in water, with the help of ultrasound to delaminate the aluminium layer. Silver is then leached using iron(III) chloride in a choline chloride: water brine. A high recovery of silver (95%) with high purity (98 wt%) is possible just by adding water to the leach liquor to precipitate silver chloride. Use of brines for the processing of metals is a new and interesting approach to replace mineral acids by cheaper and environmentally friendlier solvents. [Display omitted] • Acid-free process for metal recycling from waste solar cell. • Complete leaching of Ag with iron(III) chloride using a brine. • Complete leaching of Al with aluminium(III) chloride in water. • Easy recovery of metals after leaching. [ABSTRACT FROM AUTHOR]

Subsurface power grids constitute one of the largest copper stocks in many industrialized cities. Over time, parts and zones of these systems have been continuously disconnected and abandoned, resulting in the emergence of urban infrastructure ores. This study aims to assess how current conditions and practices influence economic and environmental motives of cable recovery from such power grids. By applying an infrastructure manager's perspective and evaluating 16 scenarios involving different extraction technologies and procedures, surface materials, urban locations and types of cables, we identify key areas where solutions or changes to increase incentives for cable recovery are needed. The assessed scenarios display significantly different cable extraction costs, where excavation in city centers with asphalt or cobblestone pavements generates the highest costs while greenbelts offer the best conditions. In most cases, cable revenues are not even close to outweighing the extraction costs. This is especially true for paper-coated cables or cables with aluminum conductors, for which the revenues are much lower than for plastic-insulated copper cables. Although economic conditions could be improved by integrating cable recovery to regular system upgrade projects or by applying non-digging technologies, clear incentives rely on the cable in question being especially valuable. Most of the cable recovery scenarios display environmental motives in terms of net savings in GHG emissions due to metal recycling. In contrast to the economic results, recycling of aluminum power cables is here more awarding than that of corresponding copper cables. We conclude that under current conditions urban mining does not make economic sense to infrastructure managers unless it is integrated as an added value to system upgrade projects. Apart from such re-arrangements in infrastructure provision, several other practice-related changes to cut cable extraction costs are possibly within reach for the managers. Still, an economically motivated practice relies on several external performance drivers such as market diffusion of non-digging technologies, improved cable recycling processes, and increased scrap metal prices. Our conclusion that the arguments for urban mining are currently more environmental than financial, points towards changed perspectives where such activities are seen as a way for infrastructure managers to contribute to societal goals such as climate change mitigation and reduced mineral resource dependence. [ABSTRACT FROM AUTHOR]

A novel and clean process was developed to convert flue dusts of secondary copper smelters into value-added products. The process consists of three main steps: NaOH leaching, two-stage combined electrolysis, and deep purification of recycle solution. Initially, 80–92% Zn and Pb were dissolved in 5 M NaOH at 80 °C, whereas Cu was concentrated in the residue. Yates' algorithm was used to determine the main effects and interactions of the leaching factors. The leach solution was then electrolyzed at 100–250 A/m 2 and high purity Pb (>97%) was separated from the alkaline solution. Subsequently, a pulsed current was introduced to obtain ultrafine zinc powders (∼30 μm) with the best performance occurred at T on (current-on) = 15 ms, and T off (current-off) = 10 ms. Finally, Cl and Al were precipitated by evaporation-condensation and CaO addition, respectively. The combination of alkaline media and pulse current enables the green route without distilled water washing and surfactant addition, thus minimizing effluent emissions. This environmentally friendly method has promise to treat other industrial wastes due to its low cost and simple design. [ABSTRACT FROM AUTHOR]

Standard material flow analysis (MFA) and life cycle assessment (LCA) models were combined to analyze the historical evolution of greenhouse gas emissions of Italian aluminum over the years 1960–2009 with the aim of providing key features to Italy for prioritizing future industrial and environmental policies. Annual greenhouse gas emissions were calculated for primary and electrical energy, process-related and transportation. Cradle-to-gate emission factors were defined per ton of aluminum produced and used to quantify the cumulative carbon footprint. Consolidation of the model was carried out at domestic and foreign levels for aluminum production in order to analyze the shift in emissions transfers between the location of production and that of use. Overall, average percent contributions from the main CO 2 e-related process reflect the trend of the global aluminum industry in upgrading to standardized production processes worldwide. Cumulative carbon footprint of Italian aluminum was estimated in about 375 MtCO 2 e, of which only 188 MtCO 2 e is from domestic production. Because Italy is a net importer of aluminum, greenhouse gas emissions from the final use of aluminum have increased the impact of domestic production by 140% in the last decade. A potential carbon emissions savings of ∼160 MtCO 2 e could result if the current anthropogenic aluminum in-use stock will be quantitatively recycled. The study showed potentials for combining MFA and LCA to improve completeness when approaching environmental issues. The outcomes revealed chances for decreasing the contribution to climate change from the aluminum industry and allowed the setting of country indicators usable in future national LCA studies. [ABSTRACT FROM AUTHOR]

Substance flow analysis (SFA) provides a helpful tool for the study of the industrial metabolism of a certain substance within a regional level. This paper presents SFA of steel in four countries, namely Australia, Brazil, China and India. These countries are traditionally economically mineral dependent and are major contributors in global iron ore production. For example, in 2010 together these countries produced 81% of world iron ore. Based on the analysis it was found that Australian and Brazilian iron ore stocks will deplete rapidly while China and India are accumulating. This paper then presents a discussion on sustainability issues related to substance flows of steel stocks. The study is aimed at providing better understanding of stocks and flows and to inform the policy making for achieving the industrial metabolism and consequently leading to better management of resources and recycling of steel in the countries under study. [ABSTRACT FROM AUTHOR]

Recycling the sludge in building materials is a promising approach to reduce construction costs and environmental pollution. However, when the sludge is used as a raw material the mechanical properties and environmental risks of sludge should be taken into consideration. In this study, heavy metals contaminated river sludge (CRS) incorporated into the production of unfired green bricks with the combination of hemihydrate phosphogypsum (HPG), ground granulated blast furnace slag (GGBFS), and Portland cement (PC). The mechanical properties of brick specimens were determined by conducting unconfined compressive strength (UCS) and water resistance tests, while the hydration products and strength formation mechanism were detected by XRD, TGA, and SEM-EDS investigation. Furthermore, the TCLP and SPLP tests were used to assess the heavy metals releasing behavior. The explored results show that the UCS of samples increases with the rise of the replacement level of PC by GGBFS. The highest UCS and softening coefficient of bricks were 15.24 MPa and 0.94 using the combinations of 60% CRS, 20% HPG along with 17% GGBFS and 3% PC. The microstructural analysis revealed that HPG could react with GGBFS and PC to generate massive ettringite (AFt). These AFt may bridge gypsum crystals to form a dense network microstructure. Additionally, specimens prepared in this study exhibited an excellent fixing capacity for heavy metals. The heavy metal immobilization rates of the optimal mixture were all higher than 99.41%. [Display omitted] • Heavy metal contaminated river sludge was used to manufacture unfired green bricks. • Compressive strength and water resistance of samples could satisfy Chinese standard. • Strength is highly dependent on PC/GGBFS ratio, citric acid content, and curing time. • The decrease of PC/GGBFS ratio could accelerate the formation of ettringite. [ABSTRACT FROM AUTHOR]

Copper indium gallium diselenide (CIGS), is a promising commercial thin-film solar cell, and its disposal after scrapping and recycling critical metals has attracted tremendous attention since CIGS can be considered an important type of urban mining. The main phase of spent CIGS is selenide, which is a hazardous contaminant that may have a potential impact on the environment and human body. In our previous study, selenium and copper in spent CIGS separated efficiently, while more scarce metals: indium and gallium were obtained in the form of mixed indium gallium oxide (IGO). Therefore, in this study, the separation and purification of indium and gallium was investigated in detail. The solution chemical behavior shows that the dissolution of indium gallium oxide (IGO) in an alkaline environment was significantly different. Selective alkali leaching is feasible to separate indium and gallium effectively. The process realized 97.26% gallium leaching out, while that of indium was 3.37%. Moreover, the mechanism of the leaching process and the removal of copper impurities were explored, with further purification, indium and gallium were obtained in the form of relatively pure indium oxide (96.04%) and gallium oxide (99.83%), respectively. This study will provide guidance for the recycling of critical metals from secondary waste. [Display omitted] • An effective process for indium gallium separation in spent CIGS was developed. • Theoretical analysis of indium gallium separation in an alkaline system was analyzed. • The high purity products were obtained after purification. • Indium and gallium were recovered as pure In 2 O 3 and Ga 2 O 3 respectively. [ABSTRACT FROM AUTHOR]

Hydrometallurgy leaching is a common method used to recycle heavy metals from electroplating sludge, but the subsequent separation of heavy metals from the complex leaching solution is difficult. In this study, Cu(II), Zn(II), and Cr(III) were sequentially recycled from electroplating sludge by an on-line biosorption method with dosage controlling. The results showed that the three metals mainly existed in their labile forms and could be leached by HNO 3. A series of amine-modified bagasse biosorbents were prepared, and diethylenetriamine-modified sorbent was chosen and fixed in a column to remove heavy metals from the leaching solution. Sorbent dosage experiments showed Cu(II) was recycled exclusively at a dosage of 1.5 g/L, while Zn(II) and Cr(III) were recycled simultaneously at a dosage of 3.8 g/L when treating 800 mL of a leaching agent containing 13.4, 9.9, and 7.1 mg/L of Cu, Zn, and Cr. A linear relationship between the dosage and amount of adsorbed metal ions was obtained. The XPS results illustrated that the column had an adsorption affinity order of Cu(II)>Zn(II), Cr(III)≫Ca(II), Mg(II). Cu(II) was enriched in the foot layer, and Zn(II) and Cr(III) were enriched in the middle layer of the column, while co-ions could not be absorbed. According to these results, Cu(II), Zn(II), and Cr(III) could be sequentially recycled by using these columns in-series. [Display omitted] ● Heavy metals were recycled from sludge in a leaching-biosorption circulation system ● Cu (II), Cr (III), and Zn (II) was sequentially separated by sorbent dosage control ● Cu (II) was selectively recycled by TETA modified bagasse at dosage of 1.2 g first ● Cr (III) and Zn (II) were then recycled efficiently at sorbent dosage≥ 2.3 g ● The method had great potential in metal recovery from the solid waste [ABSTRACT FROM AUTHOR]

The implementation of energy systems and technologies has been incentivized by the assessment of various aspects, including social and economic acceptance and sharing rational technology targets. In this study, battery-assisted hydrogen production systems were analyzed with regard to their environmental and techno-economic aspects. The costs of hydrogen production were minimized by the capacity optimization of the system components based on different development levels of contained technologies. The cost minimization indicated the upper limit of battery cost for reducing hydrogen cost. The relation with the cost of electrolyzer can be formulated in some assumptions. Greenhouse gas emissions and the abiotic resource depletion of cost-minimized systems were also analyzed. The performance of battery-assisted hydrogen production on unit cost and greenhouse gas emission may be high enough to be competitive with other hydrogen production or fossil fuel use. In contrast, the environmental impact of this system on the abiotic resource depletion is too large to be environmentally competitive to other options. Technology and system improvements such as metal recycling are important factors for the system. [ABSTRACT FROM AUTHOR]

The significant development in advanced technologies such as lithium-ion batteries has increased the demand of cobalt and nickel. As a result, continuous supply from primary resources leads cobalt to the critical stage and also affects nickel resources extensively. The presence of limited resources can lead to break in the chain of supply of these metals on demand. Therefore, it is necessary to recycle cobalt and nickel from secondary resources in order to continue the chain of demand and supply. This review provides a detail on solvent extraction processes developed for the separation and recovery of cobalt and nickel from secondary resources in the last decade. The study illustrates applicability of different type of extractants to provide better separation and recovery of said metals from potential wastes originated from different sources. The fundamentals of solvent extraction along with mechanisms of different class of extractants involved in the recycling of metals have been discussed in detail. • SX processes for Co and Ni recovery from spent matrices are reviewed. • The applicability and potential of ionic liquids in SX is reported. • Research gap between academic research and larger scale operations is identified. • Need of a greener and cost-effective process is recommended. [ABSTRACT FROM AUTHOR]

Waste electrical and electronic equipment (WEEE) or simply e-waste have been gaining attention around the world due to their rapid generation and potential economic values. While a number of global and regional estimations of e-waste have been conducted, the current and future magnitude of e-waste in Indonesia, the world's fourth largest population, has not been thoroughly assessed. This study aims to provide an estimation and projection of e-waste generation in Indonesia, as well as its potential recoverable metals' value from 1996 to 2040 to address this gap. An advanced multivariate Input-Output Analysis (IOA) of sales-stock-lifespan model and a dynamic, time-variant lifespan of products through Weibull distribution function were used to provide more accurate and extended estimation of e-waste generation in Indonesia. The results show that Indonesia's e-waste generation is projected to increase from approximately 2.0 (in 2021) to 3.2 million tonnes (in 2040), which corresponds to 7.3 (in 2021) to 10 kg/capita (in 2040). These represent economic values from US$ 2.2 billion to US$ 14 billion of Copper, Gold, Silver, Platinum and Palladium in the e-waste. This study also maps the distribution of e-waste generation in Indonesia and found that in 2021, the Java Island contributes up to 56% of the total e-waste generation in the country. Lastly, the study proposes a recycling system framework that include possible processing routes and scenarios that integrate mobile/sub-station recycling facilities to existing large metallurgical facilities in the context of Indonesia archipelago. • Indonesia's WEEE generation was predicted to increase from 7.3 (2021) to 10 kg/capita (2040). • Indonesia's WEEE generation was predicted to increase from 2.0 (2021) to 3.2 MT (2040). • The Java Island was found to contribute up to 56% of Indonesia's 2021 e-waste generation. • The values of key metals in Indonesia's e-waste were predicted to be US$ 14 billion in 2040. • Mobile/sub-station recycling facilities play important role in the recycling system. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are commercially used in an increasing number of critical or widely popular consumer and industrial products. Neodymium (Nd) element has emerged in recent years as one of the most critical REE, due to risks associated with its security of supply at required amounts. It has been widely reported that end of life (EoL) consumer electrical products contain significant amounts of metals and plastics. Thus, recovery of Nd from magnet scraps, EoL appliances or industrial applications is gaining even more strategic importance nowadays. In this study, an ex-ante life cycle assessment (LCA) of the hydrometallurgical recovery of Nd from waste electric and electronic equipment (WEEE) was conducted. The hydrometallurgical Nd recovery route consists of pretreatment, chemical leaching and Nd metal precipitation The feasibility and environmental performance of Nd metal recycling experiment model was investigated with an LCA scenario focusing on neodymium-iron-boron (Nd-Fe-B) magnet production. The LCA results were compared to that due to Nd-Fe-B magnet production from bastnäsite/monazite mineral ores using the traditional sintered magnet route. LCA sensitivity analysis and cost analysis were also performed. It was found out that, from both an economical and environmental point of view, magnet production from recovered Nd performed better than that of virgin magnet production. The scaled-up Nd metal recovery system reduced environmental impacts of Nd-Fe-B magnet production system by up to 65% for eight of the eleven environmental impact categories. Nd recycling reduced production cost from 8.55 to 3.98 USD/kg. • Ex-ante LCA was conducted for hydrometallurgical recovery of Nd from spent magnet. • Scaled-up Nd recovery reduced environmental impacts of Nd-Fe-B magnet production. • Magnet production from recovered Nd is more economical than virgin magnet production. [ABSTRACT FROM AUTHOR]

Recycling waste multilayer ceramic capacitors (MLCCs) has attracted much attention owing to its rich metal resource and environment pollution. Existing recycling processes have deficiencies in environmental protection, efficiency and metal purity. Capture technology is promising with advantages of efficient enrichment and less pollution, which was applied to recycle metals in this study. In order to study the mechanism for it, the behavior of enrichment and migration of metals in the recovery of waste MLCCs by eutectic capture of copper was discussed. The recovery rates of Ag, Pd and Bi were 87.53%, 100% and 100%, respectively. Alloy (Cu–Ag–Pd–Bi–Pb) and recyclable slag were obtained. There were three phases of Ag, Cu–Pd and Bi–Pb with the analysis of morphology and composition for the alloy. Then the capture mechanism was revealed. The slag and metal separated due to differences in chemical bonds, surface energy, density and viscosity. The interaction of metals was analyzed through phase diagrams and density functional theory. Pd tended to enter Cu phase. Ag and Cu existed as two phases. Bi and Pb neither entered Ag nor Cu phase based on phase diagrams and formation energy. This study provides a theoretical basis for the application of capture technology in metal enrichment. Image 1 • An efficient process for recycling waste MLCCs was proposed by copper capture. • The separation process of slag and metals was analyzed in copper capture process. • The interaction of metals was analyzed through phase diagrams and formation energy. [ABSTRACT FROM AUTHOR]

Copper-based mixed wastes include copper-containing wastes from the chemical, metallurgy, copper processing, printing, electronic component manufacturing, and other industries. Copper-based mixed wastes have high humidity and a significantly lower copper content than general waste copper, pose serious environmental hazards, and are very difficult to recover. The recycling of copper-based mixed wastes has important economic and environmental significance. Chinese companies have started extracting copper and other metals from copper-based waste mixtures and have achieved a high economic efficiency. This paper assesses the environmental impacts of copper-based mixed waste recycling and suggests possible optimization measures for the production process with respect to environmental impacts. The life cycle assessment (LCA) method is adopted to evaluate the effects of different production processes and to compare the environmental impacts of copper recovery from copper-based mixed waste recycling to the environmental impacts of primary and secondary copper production. Sensitivity analysis is conducted to estimate and evaluate the effects of possible production process optimization measures on environmental impacts. The results show the following: 1) The environmental impact of the copper-based mixed waste recovery process is generally superior to that of primary copper production in China on average, while it is inferior to that of secondary copper production. For example, the fossil energy consumption in primary copper production accounts for 74.9% of the impact of this process. 2) Smelting is the production process with the greatest environmental impact throughout the life cycle of copper-based mixed waste, accounting for 64.5% of the normalized index of the total environmental impact; and electrolysis and zinc recovery reach 19.8% and 12.1% of the total normalized index, respectively. 3) The raw materials and emission components with the largest environmental impacts are the carbon emissions from coal use and carbon dioxide emissions during smelting, the use of electricity during electrolysis, and the use of heavy oil and lime as raw materials during refining; these five items account for 69.7% of the total environmental impact. Thus, efforts at process improvement should focus on the full life cycle of energy utilization in the smelting process and on energy and material depletion in the refining and electrolysis processes. Specific process improvements and simulation analyses are important directions for further research. • The impact of the copper-based mixed waste recovery process is generally superior to that of primary copper production in China on average. • Smelting is the production process with the greatest environmental impact. • Five input-output items account for 69.7% of the total environmental impact. [ABSTRACT FROM AUTHOR]

High-value-added hazardous selenium sludge extracted from copper anode slime may cause serious selenium contamination and potential threats to human health if improperly treated. In this study, a sustainable chemical reaction-free vacuum separation process was used to extract selenium and recycle valuable metals from selenium sludge. The process comprises low-pressure dehydration and Se extraction by vacuum distillation. The laboratory-scale results indicate that 90.76% of selenium was extracted from volatiles at a purity of 98.68% under the optimum distillation conditions of 693 K, 90 min and 30–50 Pa. Ag and Au were enriched to 28004 g/t and 1226 g/t in residues from 2560 g/t and 112 g/t, respectively, in raw materials, representing increases of 10.4 and 10.25 times. On this basis, a low-pressure melting-vacuum distillation process and equipment with an annual selenium sludge disposal capacity of 500 metric tons were developed for industrial production. The continuous production data show that the purity of the extracted selenium always exceeded 98.0%, the direct yield ratio of selenium exceeded 96.5%, and the consumption was only 1150 kW h electricity per ton of selenium ingot output. Additionally, Ag and Au were enriched by over 11 times in the residue. The discharged water evaporated, and residues were returned to the comprehensive copper anode slime treatment process for the further valuable metal extraction. Compared with chemical processes, the proposed technology consumes fewer resources and reduces the environmental impacts, resulting in better economic and sustainability assessment results. The proposed process meets the demand for cleaner production within the selenium metallurgical industry. Image 1 • A sustainable chemical reaction-free vacuum separation process is proposed. • Selenium is cleanly extracted from high-value-added hazardous selenium sludge. • Residues and discharged water are not hazardous materials and can be further recycled. • A 500 T selenium sludge disposal capacity was developed for industrial production. [ABSTRACT FROM AUTHOR]

Copper and nickel are important metals for our society. Developing countries depend on copper and nickel for the construction of their infrastructure. Copper and nickel are also key elements for the transition to a fossil free electric energy production, which might lead to increased demand for these metals. The purpose of this paper is to investigate whether and at which conditions a sustainable production rate of copper and nickel can be combined with an increase of the service level of the two metals for the entire future world population to the same level as in developed countries in 2020. We consider three ambition levels with regard to a sustainable production rate for copper and nickel: 1000 years, 500 years and 200 years of guaranteed, sufficient and affordable supply to the entire world population at a service level, which, in all countries, is equal to the service level in developed countries in 2020. The conclusion is that the highest sustainability ambition (1000 years) is only achievable with a combination of an optimistically large amount of available resources in combination with a high end-of-life recycling rate. Whether the required amount of resources will be available for an affordable price, remains uncertain. • Three ambition levels with regard to long term supply of copper and nickel are considered: 1000, 500 and 200 years. • The aspiration: resources are available for the entire world population at the level of developed countries in 2020. • The amount of available copper and nickel resources is uncertain. • The resources necessary for providing the world sufficiently depend on the recycling rate and the ambition level. [ABSTRACT FROM AUTHOR]