The rapid generation of electronic waste (e-waste) has become a global problem owing to its potential environmental pollution and human-health risk, especially from informal recycling in developing countries. In 2014, however, only ∼15.5% of the total global e-waste was formally treated by national take-back programs. Waste printed circuit boards (PCBs) are an integral part of e-waste, and they contain many valuable metal resources. Most recycling from waste PCBs has focused on metals like Au, platinum group metals, and Cu, which have high economic value, but tin also makes up a large proportion of the metal in waste PCBs. Over the past decade, ∼44% of the refined tin has been used as solder in the electronics industry each year. Although current global tin reserves can meet the short-term demand, for long-term sustainable development, recycling tin from secondary resources, especially from e-waste, is essential. For addressing the shortage of mineral resources and conserving energy, tin recycling from e-waste needs more attention.Keywords: E-waste; Recycling; Sustainability; Tin; Waste PCBs;

An efficient mechano-thermal method was developed for lead removal from the CRTs funnel glass. The method comprises the activation of funnel glass with carbon by the planetary ball-milling apparatus. The mixture has been sintered for different lengths of time. The separation phenomenon was accelerated by the thermal treatment in the presence of carbon, the lead oxide (PbO) in a funnel glass quickly reduced into Pb and assembled on the surface of the glass matrix. With acid leaching, lead was efficiently removed from the treated glass residues. The optimum temperature, carbon powder adding amount, and holding time were 900 °C, 10%, and 30 min, respectively. During the process, more than 99 wt% of lead can be volatilized from the funnel glass and 93.60 wt% of lead was removed by the leaching process. The findings in this study provides an efficient and practical application for CRTs funnel glass detoxification and reutilization.Download high-res image (304KB)Download full-size image

•E-waste management covers four levels of product, component, material, and substance.•Material compatibility, fatigue, and reclaiming have gained much attention.•Material fatigue can determine the reverse logistics of e-waste.•Future management should be concerned from macroscopic and mesoscopic to microscopic scales.Waste electrical and electronic equipment (WEEE or e-waste) has become a global problem, due to its potential environmental pollution and human health risk, and its containing valuable resources (e.g., metals, plastics). Recycling for e-waste will be a necessity, not only to address the shortage of mineral resources for electronics industry, but also to decline environmental pollution and human health risk. To systematically solve the e-waste problem, more attention of e-waste management should transfer from macroscopic to microscopic scales. E-waste processing technology should be significantly improved to diminish and even avoid toxic substance entering into downstream of material. The regulation or policy related to new production of hazardous substances in recycled materials should also be carried out on the agenda. All the findings can hopefully improve WEEE legislation for regulated countries and non-regulated countries.Download high-res image (87KB)Download full-size image

•The generation of waste mobile phones from 2016 to 2025 in China was predicted.•Detailed components and composition of waste mobile phones were stated.•Content of typical metal in PCBs from waste mobile phones were analyzed.•Potential recycling availability of 9 metals and relationship with global production were put forward, especially for Au.Mobile phone is the most commonly used electrical and electronic equipment all over the world, resulting in the generation of a large quantity of waste mobile phones (WMPs). Manual dismantling and experimental analysis were carried out to identify the physical composition and content of 10 typical metals in printed circuited boards (PCB) from WMPs. The results showed that the content of Au ranged from 0.86 mg/g to1.60 mg/g per PCB, from 0.14 to 5.8 mg/g for Ag, 14.1–28.5 mg/g for Ni, 0.04–0.4 mg/g for Pb, and 33.9–60.1 mg/g for Sn. The amount of Cu remained stable, at 259–550 mg/g, but Pd was not detected in any of the selected samples. Taking the predicted quantities of waste metals from WMPs in 2025 in China as an example, a considerable amount of metals could be potentially recovered from PCBs, including about 9.01 t (metric ton) of Au, and 14.91 t of Ag, based on the assumption of 100% recycling. The ratio of recycled Au to global Au production would have grown at a rate between 0.07 and 0.19%, from 2010 to 2015. Recycling all of the ten metals studied would yield a profit of more than 300 million dollars by 2025. The potential amount of Au recycled from WMPs could provide about 10% of the global Au demand for electronics manufacturing, making this metal definitely worth recycling.

Urban mining is essential for continued natural resource extraction. The recovery of rare and precious metals (RPMs) from urban mines has attracted increasing attention from both academic and industrial sectors, because of the broad application and high price of RPMs, and their low content in natural ores. This study summarizes the distribution characteristics of various RPMs in urban mines, and the advantages and shortcomings of various technologies for RPM recovery from urban mines, including both conventional (pyrometallurgical, hydrometallurgical, and biometallurgical processing), and emerging (electrochemical, supercritical fluid, mechanochemical, and ionic liquids processing) technologies. Mechanical/physical technologies are commonly employed to separate RPMs from nonmetallic components in a pre-treatment process. A pyrometallurgical process is often used for RPM recovery, although the expensive equipment required has limited its use in small and medium-sized enterprises. Hydrometallurgical processing is effective and easy to operate, with high selectivity of target metals and high recovery efficiency of RPMs, compared to pyrometallurgy. Biometallurgy, though, has shown the most promise for leaching RPMs from urban mines, because of its low cost and environmental friendliness. Newly developed technologies—electrochemical, supercritical fluid, ionic liquid, and mechanochemical—have offered new choices and achieved some success in laboratory experiments, especially as efficient and environmentally friendly methods of recycling RPMs. With continuing advances in science and technology, more technologies will no doubt be developed in this field, and be able to contribute to the sustainability of RPM mining.

The effect of mechanical activation (MA) on the kinetics of terbium (Tb) leaching from waste phosphors using hydrochloric acid was investigated. Leaching kinetics, such as apparent reaction rate, activation energy and reaction order, were determined using the shrinking-core model and the Arrhenius equation. Results obtained from experiments with different concentrations of HCl and under different leaching temperatures were used for the determinations. The impacts of factors such as rotational speed, HCl concentration and leaching temperature on the leaching rate of Tb were also discussed. The results showed that MA could dramatically increase the leaching rate of Tb from waste phosphors, and the apparent reaction rate (kap) of leaching was accelerated as well. For inactivated waste phosphors, the apparent activation energy (Eap) was 52.82±3.95 kJ/mol, indicating that the rate-controlling step of the leaching process was the chemical reaction. The Eap dropped to 25.96 ±3.90 kJ/mol and 10.96±2.79 kJ/mol when the waste phosphors were mechanically activated at rotational speeds of 400 and 600 r/min, respectively; the leaching process transformed to a hybrid (chemical-reaction and diffusion) control process, and even a reagent-diffusion (through the product layer) control process. The apparent reaction order for Tb leaching from 400 r/min-activated waste phosphors was 2.49±0.11, and it decreased to 1.16±0.17 when the rotational speed of 600 r/min was used. Kinetics results indicated that MA could make Tb leaching occur spontaneously, and the activation intensity of waste phosphors was strengthened with higher rotational speed.Effects of mechanical activation on apparent activation energy and reaction order of Tb leaching from inactivated and activated waste phosphorsDownload high-res image (98KB)Download full-size image

Polybrominated diphenyl ethers (PBDEs), especially commercial decabrominated diphenyl ethers (c-decaBDE), have been widely produced and applied to numerous materials because of their highly effective flame-retardant capabilities. The production of commercial pentaBDE (c-pentaBDE) and commercial octaBDE (c-octaBDE) ended in 2004 because they are persistent, bioaccumulative, and toxic to both humans and the environment, but decaBDE production and use continue. Furthermore, many congeners of PBDEs are still prevalent in consumer products and articles that they pose enormous threat to both the environment and human health. PBDEs have been detected in the casing of electrical and electronic equipment, textile materials, automotive interiors, polyurethane foam (PUF) in seat cushions, children’s toys, kitchenware, and other products. With increasing evidence about PBDE pollution and the adoption of international conventions, many developed countries have drawn more public attention to PBDEs and developed sound strategies for their management. This review summaries the utilization and management of PBDEs in a number of countries and reaches the conclusion that PBDEs are still prevalent in consumer articles, while specific regulations or policies for articles containing PBDEs are rare. Public awareness should be raised on the importance of sound management of articles containing PBDEs.

•Perception overview of remanufacturing implementation.•Implemented methods for a revers end of life e-products.•Evaluated situation of remanufacturing between China and remanufacturing companies from Europe (Glasgow-UK).•Remanufacturing barriers.The electrical and electronic equipment (EEE) industry has increased its mass production; however, the EEE life span has similarly diminished. Owing to the rapid expansion of manufacturing, innovation and consumer demand, there has been a vast improvement in various electronic equipment, so the amount of waste electrical and electronic equipment (WEEE, or e-waste) generated has also increased proportionally to production. The main objective of this article is to evaluate the remanufacturing concept which can be adopt by the electronic manufacturing industry. The article reveals differential steps debated by industry as well as academia in assets to reduce the amount of e-waste. The concept of e-waste remanufacturing is quite dissimilar from case studies among developing and developed countries and regions. The findings can assist the academic research and leads to industry regardless remanufacturing of used EEE or WEEE by exemplifying different methods and ideologies of remanufacturing implementation plus the main issues in this field.

•High leaching rates of rare earth elements (REEs) in waste phosphors are achieved.•Mechanical activation (MA) can significantly enhance the leaching of REEs.•Mechanism of enhancement by MA is explored.•Structure destruction, even decomposition, is the dominating cause for enhancement.Rare earth elements (REEs) make up more than 23 wt% of phosphors in fluorescent lamps (FLs). The REEs recovering from waste phosphors is becoming a critical issue since REEs are considered critical elements, being important in future sustainable applications e.g. wind power, electric vehicles, energy efficient lighting, etc., and also, the accelerated generation of waste FLs. In this present study, mechanical activation (MA) was innovatively employed to pre-treat waste phosphors to recover REEs effectively by an acid leaching process. The results showed the feasibility of using MA to enhance the leaching rate of REEs. The leaching rates of terbium (Tb), lanthanum (La) and cerium (Ce) had a significant enhancement of around 90%; and the leaching rates for europium (Eu) and yttrium (Y) were 93.1% and 94.6%, respectively. Moreover, the mechanism for REEs leaching rates enhancement introduced by MA was explored. Substantial physicochemical changes appeared to be the main causes leading to the effectiveness of mechanical activation for phosphors. These changes include structural destruction and compound decomposition, rather than an increase in specific surface area and a reduction in particle size. All these findings and results indicate that this novel application of MA for enhancing the recovery of REEs from waste phosphors is a promising route.Download high-res image (264KB)Download full-size image

•The information presented in this article highlights a concise overview of current WEEE recycling situation.•The methods and technologies used by various researchers have been discussed.•The environmental impact study should be carried out to assess the environmental and health risks of the recycling of WEEE.•Updated eco-friendly hybrid recycling technology and metal recovery outlined.Most waste electrical and electronic equipment (WEEE or E-waste) is recycle in the informal sector, even though—many more sophisticated recycling technologies are available. Mechanical recycling, usually the first step, can achieve maximum metal extraction, however has direct or indirect health effects, higher capital costs, and results in the loss of numerous secondary metal resources. The second most commonly used approach is the chemical method, which is much faster than the biological one, but chemical hydrometallurgy is metal-specific and also causes secondary pollution. The third approach—microbial metal recovery—is an eco-friendly and promising technology for WEEE processing. This comprehensive review evaluates and provides details of recent trends and developments in various technologies, including: physical, chemical and biological methods for the recycling and recovery of secondary resource materials, such as valuable metals. Although no single approach by itself is adequate, and as it cannot achieve ecofriendly high extraction rates of metals from WEEE, it is possible to develop a combined process, such as the initial use of mechanical treatment followed by leaching with either easily biodegradable reagents or organic acids produced by microbes—this would be more ecofriendly and economically feasible. Therefore, this article highlights specific gaps in the available technology for solving the e-waste issue, and recommends a hybrid strategy as the best available approach.

Newly defined categories of WEEE have increased the types of China’s regulated WEEE from 5 to 14. Identification of the amounts and valuable-resource components of the “new” WEEE generated is critical to solving the e-waste problem, for both governmental policy decisions and recycling enterprise expansions. This study first estimates and predicts China’s new WEEE generation for the period of 2010–2030 using material flow analysis and the lifespan model of the Weibull distribution, then determines the amounts of valuable resources (e.g., base materials, precious metals, and rare-earth minerals) encased annually in WEEE, and their dynamic transfer from in-use stock to waste. Main findings include the following: (i) China will generate 15.5 and 28.4 million tons WEEE in 2020 and 2030, respectively, and has already overtaken the U.S. to become the world’s leading producer of e-waste; (ii) among all the types of WEEE, air conditioners, desktop personal computers, refrigerators, and washing machines contribute over 70% of total WEEE by weight. The two categories of EEE—electronic devices and electrical appliances—each contribute about half of total WEEE by weight; (iii) more and more valuable resources have been transferred from in-use products to WEEE, significantly enhancing the recycling potential of WEEE from an economic perspective; and (iv) WEEE recycling potential has been evolving from ∼16 (10–22) billion US$ in 2010, to an anticipated ∼42 (26–58) billion US$ in 2020 and ∼73.4 (44.5–103.4) billion US$ by 2030. All the obtained results can improve the knowledge base for closing the loop of WEEE recycling, and contribute to governmental policy making and the recycling industry’s business development.

To minimize electronic waste and reduce the environmental impact of hazardous metals, a new greener approach has been developed for the extraction of lead and barium metals from waste cathode ray tube (CRT) glass. The process steps comprise an initial mechanical activation of CRT funnel glass and then wet ball milling of the funnel glass powder using the metal chelate reagent 2-[bis(carboxymethyl)amino]acetic acid (NTA) and water at room temperature. After the mechanochemical treatment, the desired ≳99 mass % of lead and barium metals contained in the funnel glass powder was extracted as a metal–NTA species and pure nonleaded SiO2 glass material from the funnel glass matrix. The separation was accelerated by the ball-milling atomization and high stability constant of the metal–NTA species. After separation, the maximal amounts of lead and barium ions (∼99 mass %) were obtained as PbSO4 and BaSO4, respectively, with the addition of ferric sulfate. Notably, the developed method does not require heat and does not generate any secondary waste. Therefore, the results show that the developed method is an innovative and sustainable process, which can also probably be applied to purify any other kind of leaded glass.Keywords: Cathode ray tubes; Lead; Mechanochemical treatment; Recycling

Informal recycling of waste (including e-waste) is an emerging source of environmental pollution in India. Polychlorinated biphenyls (PCBs), polychlorinated diphenyl ethers (PBDEs), and heavy metals, among other substances, are a major health concern for workers engaged in waste disposal and processing, and for residents living near these facilities, and are also a detriment to the natural environment. The main objective of this review article was to evaluate the status of these impacts. The review found that, huge quantity of e-waste/waste generated, only a small amount is treated formally; the remainder is processed through the informal sector. We also evaluated the exposure pathways, both direct and indirect, and the human body load markers (e.g., serum, blood, breast milk, urine, and hair), and assessed the evidence for the association between these markers and e-waste exposure. Our results indicated that the open dumping and informal e-waste recycling systems should be replaced by the best available technology and environmental practices, with proper monitoring and regular awareness programs for workers and residents. Further and more detailed investigation in this area is also recommended.

Waste electrical and electronic equipment (e-waste) is the most rapidly growing waste stream in the world, and the majority of the residues are openly disposed of in developing countries. Waste printed circuit boards (WPCBs) make up the major portion of e-waste, and their informal recycling can cause environmental pollution and health risks. Furthermore, the conventional disposal and recycling techniques—mechanical treatments used to recover valuable metals, including copper—are not sustainable in the long term. Chemical leaching is rapid and efficient but causes secondary pollution. Bioleaching is a promising approach, eco-friendly and economically feasible, but it is slower process. This review considers the recycling potential of microbes and suggests an integrated bioleaching approach for Cu extraction and recovery from WPCBs. The proposed recycling system should be more effective, efficient and both technically and economically feasible.

Recycling metals from wastes is essential to a resource-efficient economy, and increasing attention from researchers has been devoted to this process in recent years, with emphasis on mechanochemistry technology. The mechanochemical method can make technically feasible the recycling of metals from some specific wastes, such as cathode ray tube (CRT) funnel glass and tungsten carbide waste, while significantly improving recycling efficiency. Particle size reduction, specific surface area increase, crystalline structure decomposition and bond breakage have been identified as the main processes occurring during the mechanochemical operations in the studies. The activation energy required decreases and reaction activity increases, after these changes with activation progress. This study presents an overall review of the applications of mechanochemistry to metal recycling from wastes. The reaction mechanisms, equipment used, method procedures, and optimized operating parameters of each case, as well as methods enhancing the activation process are discussed in detail. The issues to be addressed and perspectives on the future development of mechanochemistry applied for metal recycling are also presented.

A number of efforts have been launched to solve the global electronic waste (e-waste) problem. The efficiency of e-waste recycling is subject to variable national legislation, technical capacity, consumer participation, and even detoxification. E-waste management activities result in procedural irregularities and risk disparities across national boundaries. We review these variables to reveal opportunities for research and policy to reduce the risks from accumulating e-waste and ineffective recycling. Full regulation and consumer participation should be controlled and reinforced to improve local e-waste system. Aiming at standardizing best practice, we alter and identify modular recycling process and infrastructure in eco-industrial parks that will be expectantly effective in countries and regions to handle the similar e-waste stream. Toxicity can be deleted through material substitution and detoxification during the life cycle of electronics. Based on the idea of “Control-Alt-Delete”, four patterns of the way forward for global e-waste recycling are proposed to meet a variety of local situations.

With rapid growth in the use of liquid crystal display (LCD) and increasing concerns for environmental protection as well as conservation of scarce metals such as indium, the recycling of indium from waste LCDs is becoming a hot issue for current society. In this study, the leaching process for indium and exploration of its mechanism were carried out with full consideration of potential theory and experiments. The optimal parameters for the leaching process is controlled at a <75 μm sample size, 180 min retention time, 50 °C temperature, H2SO4 for the leaching agent, 100 g/L initial concentration, and 1:1 liquid–solid ratio. The initial samples and leaching yields were examined with the necessary analytical techniques including SEM, XRF, EDS, XRD, FTIR, and ICP. We also found that the leaching process could largely modify raw material and enhance its activation for further recovery. All the obtained results and findings could contribute to affording a closed-loop recycling process for waste LCDs and sustainable development of indium industries.Keywords: E-waste; Green chemistry; Indium; Liquid crystal display; Process; Recycling

In the context of huge imbalance between increasing demand for metals and the finiteness of metal resources in nature, recycling metal from second-hand resources, especially e-waste, is of great importance, to embrace the sustainability challenge. Inspired by its hundreds of uses in extractive metallurgy, mechanochemistry has been introduced to recover metals from waste since the 1990s. The mechanochemical recycling process is technically feasible to recover metals from waste in a high yield, such as Pb recovery from cathode ray tube (CRT) funnel glass, Li and Co recovery from lithium-ion batteries, rare earth recovery from fluorescent lamps. In recovery from LCD screens, Cu recovery from waste printed circuit boards and Au, Mo and Ni recovery from waste. Particle size reduction, specific surface area increase, crystalline structure decomposition and bond breakage have been identified as the main changes induced by the mechanochemical processes in the studies. Also, the activation energy required decreases and reaction activity increases, subsequently. This paper presents a technical overview of the applications of mechanochemistry to metal recycling from waste. The current application pattern, reaction mechanisms, equipment used, method procedures, and the future research direction are discussed in detail. This work presents the limitation of current mechanochemical application in metal recovery and gives a perspective of the future development of mechanochemistry as well.

The rapid increase in production and usage of fluorescent lamps (FLs) has brought with it a rising concern about potential mercury risk from both FL production and disposal at the end-of-life (EoL) stage. Thus, there is an urgent need for the environmentally sound management of FLs. In order to provide useful information for the development of effective management tools, this study used the life cycle assessment methodology to investigate the environmental performance of FLs in China.This work compares the environmental performance of two types of FLs, linear (LFLs) and compact (CFLs), using the modular life cycle assessment (LCA) based on the international standards of the ISO 14040 series. The operational data applied to the inventory analysis and combined with the information in the Ecoinvent 3.0 databases was obtained by interviews with a local FL manufacturer and a licensed waste FL treatment facility.Results suggest that the chosen linear FL has a lower environmental impact than the compact one. The use stage accounted for the majority (>94 %) of total environmental impacts, followed by the manufacturing stage. The ballast component was the largest contributor to the environmental impact of CFLs and largely accounted for the difference between CFLs and LFLs in the manufacturing stage. The end-of-life stage can be a benefit to the environment when waste FLs are processed through the proper, licensed disposal enterprises in China. Electricity consumption accounts for more than 94 % of the environmental impact of FLs over their entire life cycle. This can be reduced by 19 % when the electricity used is changed from the Beijing mix to the China mix.Results of the life cycle assessment can be used to compare relative environmental impacts of different waste FL treatment technologies and can help policy makers better understand the urgency of the issues calling for their attention.

In the context of recycling metal to embrace the sustainability challenge, this work employs mechanochemistry to recover copper from waste printed circuit boards (WPCBs) for the first time. This work aims to recycle both copper (9.89 wt%) and resin, the two main components of WPCBs, to the largest extent. Copper and sulfur could be reacted to form copper sulfides by the aid of mechanochemistry in the model experiment, so the synergistic route of mechanical activation and sulfurization was proposed. After milling WPCB fragments and sulfur for 20 minutes and leaching as-milled sample in sulfuric acid (3 M) and hydrogen peroxide (30 wt%), the yield of copper reached nearly 90% and, also, resin was conserved for further utilization. This paper highlights the microstructural assessment of the synergism of mechanical activation and sulfurization. It is an alternative method for recycling a metal to transform it into a corresponding compound that exists in natural minerals, and mechanochemistry can help to fulfil this process in a green way.

The amount of spent rechargeable lithium batteries (RLBs) is growing rapidly owing to wide application of these batteries in portable electronic devices and electric vehicles, which obliges that spent RLBs should be handled properly. Identification of spent RLBs can supply fundamental information for spent RLBs recycling. This study aimed to determine the differences of physical components and chemical compositions among various spent RLBs. All the samplings of RLBs were rigorously dismantled and measured by an inductive coupled plasma atomic emission spectrometer. The results indicate that the average of total weight of the separator, the anode and the cathode accounted for over 60% of all the RLBs. The weight ratio of valuable metals ranged from 26% to 76%, and approximately 20% of total weight was Cu and Al. Moreover, no significant differences were found among different manufacturers, applications, and electrolyte types. And regarding portable electronic devices, there is also no significant difference in the Co-Li concentration ratios in the leaching liquid of RLBs.

The quantity of vehicles has increased rapidly in recent years in China; however, the recycling of End of Life Vehicles (ELV) faces several problems and barriers including the collection difficulty and the environmental pollution caused by improper dismantling. In this paper, based on analysis of the basic situation regarding management and recycling of ELV in China, the ELV flow was introduced, and the potential ELV quantity was estimated. The current management regulations and policies were summarized, and dismantling and pollution control technologies for ELV recycling were introduced, too. It was suggested that with the rapid growth of ELV quantities, more regulations will be enacted, and the recycling network will be more effective; the dismantling technology and pollution control measures will be upgraded, and the recycling and remanufacturing industries will be more combined. The government should pay more attention to improve the management and supervision of, and encourage the development of, high level enterprises.

Cathode ray tube (CRT) funnel glass remains an urgent environmental problem and is composed mainly of lead oxide and silicon oxide. In this research, the residue could be obtained from 2 h to 500 rpm activated CRT funnel glass after extracting lead via acid leaching under the conditions of HNO3 concentration 1.0 mol/L, leaching temperature 95 °C and leaching time 1 h. In order to reutilize the residue, its physico-chemical properties were characterized by scanning electron microscopy, Brunauer–Emmett–Teller, thermogravimetric analysis, X-ray diffraction and Fourier transform infrared spectroscopy. The results indicated that the residue was an amorphous superfine powder with approximately 93 wt% silica oxide and specific surface area of more than 170 m2/g. It can be reutilized as white carbon black.

This paper indicates that the performance of tack-back and treatment of electronic waste (e-waste) system can be improved substantially. This can be reached by better taking into account in a better way the big variety in material composition and potential toxicity of electrical and electronic products - from a technical, organizational and regulatory perspective. Realizing that there is no ‘one size fit for all’ and combining smart tailor made solutions with economic of sale will result in the best environmental gain/cost ratio. Several examples show how science and engineering have supported or will support this approach.

The disposal of scrap cathode ray tube (CRT) funnel glass has become a global environmental problem due to the rapid shrinkage of new CRT monitor demand, which greatly reduces the reuse for remanufacturing. To detoxificate CRT funnel glass by lead recovery with traditional metallurgical methods, mechanical activation by ball milling was introduced to pretreat the funnel glass. As a result, substantial physicochemical changes have been observed after mechanical activation including chemical breakage and defects formation in glass inner structure. These changes contribute to the easy dissolution of the activated sample in solution. High yield of 92.5% of lead from activated CRT funnel glass by diluted nitric acid leaching and successful formation of lead sulfide by sulfur sulfidization in water have also been achieved. All the results indicate that the application of mechanical activation on recovering lead from CRT funnel glass is efficient and promising, which is also probably appropriate to detoxificate any other kind of leaded glass.

Many developing countries have not significantly changed their course with regard to electronic waste contamination, and they are still facing the specter of mountains of hazardous electronic waste, with serious consequences for both the environment and public health. An efficient and stable analytical method was developed to determine the inventory and emission factors of polybrominated dibenzo-p-dioxin and dibenzofurans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formed from the incineration of scrap printed circuit boards (PCBs). Both PBDD/Fs and PCDD/Fs have been found in all experimental sections with a maximum formation rate at temperatures between 250 and 400 °C. The amounts tended first to increase and then began to decrease as the temperature rose. When subjected to a heating temperature of 325 °C, the total content of twelve 2,3,7,8-substituted PBDD/Fs congeners (tetra- through octabromo-) gathered from three outputs was the largest, at 19 000, 160 000, and 57 ng TEQ/kg in solid, liquid, and gaseous fractions, respectively; the total content of seventeen 2,3,7,8-substituted PCDD/Fs congeners (tetra- through octachloro-) was 820, 550, and 1.4 ng TEQ/kg. The formation of PCDD/Fs was remarkably less than that of PBDD/Fs because bromine concentrations considerably exceeded chlorine concentrations. The ingredients and conditions necessary to form PCDD/Fs or PBDD/Fs were definitely present, such as products of incomplete combustion, halogenides, an oxidizing atmosphere, and a catalyst—Cu salts being the most effective, significantly increasing the yields of PCDD/Fs and PBDD/Fs and decreasing the optimum temperature range.

The circular economy has been developing rapidly in recent years in China. A legislative system has been created to provide legal protection for the development of a circular economy, including a series of price and tax measures in the waste management area. These measures form the basic foundation for promoting better waste management under the circular economic model. Many challenges, however, remain. For instance, the legal system needs to incorporate more sophisticated science, and China lacks key waste treatment technology that could support the further development of a circular economy. There is also a need to educate the public about the concept of the circular economy and its benefits. Specific suggestions are made for the development and implementation of the circular economic model.

Mechanical waste-processing methods, which combine crushing and separation processes for the recovery of valuable materials, have been widely applied in waste printed wiring board (PWB) treatment. However, both the high impact toughness and the tensile and flexural strengths of whole PWB with a laminated structure result in great energy consumption and severe abrasion of the cutters during multi-level crushing. In addition, the high temperatures occurring in continual crushing probably cause the decomposition of the polymer matrix. A thermal-crack method using residual steam as the heating medium has been developed to pre-treat waste PWBs. This treatment reduces the mechanical strength in order to improve the recovery rate of valuable materials in subsequent mechanical recycling. The changes of the PWBs’ macro-mechanical properties were studied to evaluate thermal expansion impacts associated with changes in temperature, and the dynamic dislocation micro-structures were observed to identify the fracture mechanism. The results showed that thermal cracking with steam at the temperature of 500 K can effectively attenuate the mechanical properties of waste PWBs, by reducing the impact, tensile and flexural strengths respectively, by 59.2%, 49.3% and 51.4%, compared to untreated PWB. Thermal expansion can also facilitate the separation of copper from glass fiber by reducing peel resistance by 95.4% at 500 K. It was revealed that the flexural fracture was a transverse cracking caused by concentrated stress when the heating temperature was less than 500 K, and shifted to a vertical cracking after exceeding 500 K.

Globally, electrical and electronic equipment (EEE) is now a part of daily life. When this equipment becomes waste electrical and electronic equipment (WEEE or E-waste), however, it needs to be properly processed, for use as a source of materials for future production and renewable energy, and to minimize both the exploitation of raw materials and the deleterious effects on both the environment and human health. A large quantity of e-waste is generated in both India and China, and both countries still suffer from an entrenched informal e-waste processing sector. Consequently, valuable materials in e-waste are disposed in open land, rather than being properly extracted for reuse and recycling. In this article we note that the major portion of e-waste in China and India is collected by the informal sector and treated with primitive methods. Additionally, illegal shifting agents also play a role by mislabeling e-waste and exporting them to developing countries. This article proposes that: the implementation of e-waste management laws and policies for proper e-waste collection, treatment and recycling, better educate consumers on the dangers of e-waste contamination, restrict the illegal movement of e-waste across borders, and support the development of a formal, regulated e-waste processing industry by funding incentive programs constructing recycling infrastructure. These measures should increase the recycling capacity and decrease the amount of WEEE contaminating the environment and endangering human health.

Low-temperature pyrolysis (LtP) has always accompanied to the recycling and treatment of printed circuit board (PCB), which would generate pollutants. In order to better understand this process and develop methods of mitigating its deleterious environmental consequences, a thermo-analytical and kinetics study on PCBs was conducted by thermo gravimetry (TG) analysis under various atmospheres and focused on low-temperature scope. Meanwhile, this paper compares literature sources about how the characteristics are exhibited of LtP on PCBs scrap using TG or TG-IR (infrared spectroscopy) experiment. The LtP process consisted mainly of three distinct phases: (a) minor mass loss but without chemical reaction, (b) slight mass loss with adhesives decomposition, and (c) rapid degradation and char decomposition from resin. The initial temperature of third phase for PCBs pyrolysis occurred in the range of 290–300 °C using a heating rate of 10 °C min−1 under N2 or air atmosphere. While the activation energy resulting in mass loss (second phase) are found to be 127.87 and 115.36 kJ mol−1 under N2 and air atmosphere, the activation energy is 53.59 kJ mol−1 under vacuum by kinetics analysis, of which the initial temperature leads to rapid degradation is decreased into 270 °C. Vacuum condition significantly improves the outcome of the pyrolysis process. With a comparison on literature sources subjected to N2 or air atmosphere, while the products released during the first phase were mainly H2O and CO2, the flame retardants and other plastic additives were decomposed or volatilized, releasing small-molecule products within the second phase, including HBr, H2O, CO2 and molecular hydrocarbons (methane, ethane, and butane). Gases and liquid substances were released from resin decomposition during the third phase; it is indicated that complete pyrolysis and carbonization occurred. The gases products are also very rich in hydroxyl-benzene and other brominated aromatics. Liquid by-products consist mainly of phenol, alkyl phenol, bisphenol A, water, and various brominated phenols.

•Material flow analysis for cobalt cycle in China is determined from 2005 to 2013.•We forecast the demand of cobalt in China.•Cumulative demand of cobalt is obtained under different recycling scenarios.•We summarize carrying capacity of cobalt resource and vision of cobalt industry.Cobalt, one of the more scarce energy metals, is widely utilized in many crucial industries. China is a major consumer and supplier of resources such that domestic cobalt are being rapidly depleted, which results in the boost of consumer electronics (CE) and electric vehicles (EV) industries vulnerable to the sustainability of cobalt reserve base. Here we summarize that China's cobalt demand will increase significantly due to the continuing growth of CE and the briskly emerging market of EV, resulting in a short carrying duration of cobalt, even with full recycling of cobalt products. With these applications increasing at an annual rate of 5%, the carrying duration of cobalt resource until 2030 will oblige the cobalt products recycling rate of not less than 90%. To sustain cobalt utilization in China, one approach for cobalt recycling would be to improve the collection system and recycling technology towards closed-loop supply chain, and other future endeavours should include commercializing the low-content cobalt battery and optimizing cobalt industrial structure.Download full-size image

•Annual and cumulative demand of lithium were predicted.•Cumulative demand for lithium under different recycling scenarios was addressed.•The future CE and EV industry, and EoL products recycling were prospected.China is a major supplier of rechargeable lithium batteries for the world's consumer electronics (CE) and electric vehicles (EV). Consequently, China's domestic lithium resources are being rapidly depleted, and the development of the CE and EV industries will be vulnerable to the carrying capacity of China's lithium reserves. Here we find that lithium demand in China will increase significantly due to the continuing growth of demand for CE and the briskly emerging market for EV, resulting in a short carrying duration of lithium, even with full recycling of end-of-life lithium products. With these applications increasing at an annual rate of 7%, the carrying duration of lithium reserves will oblige the end-of-life products recycling with a 90% rate. To sustain the lithium industry, one approach would be to develop the collection system and recycling technology of lithium-containing waste for closed-loop lithium recycling, and other future endeavors should include developing the low-lithium battery and optimizing lithium industrial structure.Download full-size image

After the deadly earthquake on May 12, 2008 in Wenchuan county of China, several different incineration approaches were used for medical waste disposal. This paper investigates the generation properties of polycyclic aromatic hydrocarbons (PAHs) during the incineration. Samples were collected from the bottom ash in an open burning slash site, surface soil at the open burning site, bottom ash from a simple incinerator, bottom ash generated from the municipal solid waste (MSW) incinerator used for medical waste disposal, and bottom ash and fly ash from an incinerator exclusively used for medical waste. The species of PAHs were analyzed, and the toxicity equivalency quantities (TEQs) of samples calculated. Analysis results indicate that the content of total PAHs in fly ash was 1.8 × 103 times higher than that in bottom ash, and that the strongly carcinogenic PAHs with four or more rings accumulated sensitively in fly ash. The test results of samples gathered from open burning site demonstrate that Acenaphthylene (ACY), Acenaphthene (ACE), Fluorene (FLU), Phenanthrene (PHE), Anthracene (ANT) and other PAHs were inclined to migrate into surrounding environment along air and surface watershed corridors, while 4- to 6-ring PAHs accumulated more likely in soil. Being consistent with other studies, it has also been confirmed that increases in both free oxygen molecules and combustion temperatures could promote the decomposition of polycyclic PAHs. In addition, without the influence of combustion conditions, there is a positive correlation between total PCDD/Fs and total PAHs, although no such relationship has been found for TEQ.Highlights► PAHs generation and distribution features of medical waste incineration are studied. ► More PAHs were found in fly ash than that in bottom ash. ► The highest proportion of PAHs consisted of the seven most carcinogenic ones. ► Increase of free oxygen molecule and burning temperature promote PAHs degradation. ► There is a moderate positive correlation between total PCDD/Fs and total PAHs.

Chlorofluorocarbons (CFCs) contained in household refrigerators consist mainly of CFC-11 and CFC-12, which will be eventually released into the environment. Consequentially, environmental releases of these refrigerants will lead to ozone depletion and contribute significantly to the greenhouse effect, if waste refrigerators are not disposed of properly. In the present paper, the potential release of residual CFCs and their substitutes from obsolete household refrigerators in China is examined, and their contributions to ozone depletion and greenhouse effect are compared with those of other recognized ozone-depleting substances (ODS) and greenhouse gases (GHGs). The results imply that annual potential amounts of released residual CFC-11 and CFC-12 will reach their maximums at 4600 and 2300 tons, respectively in 2011, and then decrease gradually to zero until 2020. Meanwhile, the amounts of their most widely used substitutes HCFC-141b and HFC-134a will keep increasing. Subsequently, the contribution ratio of these CFCs and their substitutes to ozone depletion will remain at 25% through 2011, and reach its peak value of 34% by 2018. The contribution to greenhouse effect will reach its peak value of 0.57% by 2010. Moreover, the contribution ratio of these CFCs to the total global release of CFCs will steadily increase, reaching its peak of 15% by 2018. Thus, this period from 2010 to 2018 is a crucial time during which residual CFCs and their substitutes from obsolete household refrigerators in China will contribute significantly to ozone depletion.

The dismantling of printed circuit board assemblies (PCBAs) and the recovery of their useful materials can lead to serious environmental impacts mainly due to their complicated physical structure and the variety of toxic elements contained in their material composition. So far, less attention has been paid to their responsible recycling compared to that of bare printed circuit boards. Combined with other materials recovery process, proper dismantling of PCBAs is beneficial to conserve scarce resources, reuse the components, and eliminate or safely dispose of hazardous materials. In analyzing the generation, resources potential and hazardous risk of scrap PCBAs, technologies used for the dismantling of waste PCBAs have been widely investigated and reviewed from the aspects of both industrial application and laboratory-scale studies. In addition, the feasibility of PCBA dismantling has been discussed, the determinants of which, including the heating conditions and mechanical properties have been identified. Moreover, this paper evaluates the environmental consequences caused by the dismantling of PCBAs.

•This study reviewed exposure routes and body burden markers of e-waste in China.•The pollutants of e-waste had entered residents’ bodies.•We recorded plausible outcomes associated with exposure to e-waste.•Children and neonates are the groups most sensitive to e-waste exposure.As China is one of the countries facing the most serious pollution and human exposure effects of e-waste in the world, much of the population there is exposed to potentially hazardous substances due to informal e-waste recycling processes. This report reviews recent studies on human exposure to e-waste in China, with particular focus on exposure routes (e.g. dietary intake, inhalation, and soil/dust ingestion) and human body burden markers (e.g. placenta, umbilical cord blood, breast milk, blood, hair, and urine) and assesses the evidence for the association between such e-waste exposure and the human body burden in China. The results suggest that residents in the e-waste exposure areas, located mainly in the three traditional e-waste recycling sites (Taizhou, Guiyu, and Qingyuan), are faced with a potential higher daily intake of these pollutants than residents in the control areas, especially via food ingestion. Moreover, pollutants (PBBs, PBDEs, PCBs, PCDD/Fs, and heavy metals) from the e-waste recycling processes were all detectable in the tissue samples at high levels, showing that they had entered residents' bodies through the environment and dietary exposure. Children and neonates are the groups most sensitive to the human body effects of e-waste exposure. We also recorded plausible outcomes associated with exposure to e-waste, including 7 types of human body burden. Although the data suggest that exposure to e-waste is harmful to health, better designed epidemiological investigations in vulnerable populations, especially neonates and children, are needed to confirm these associations.

•This study reviewed environmental effects of heavy metals from e-waste in China.•High concentrations of heavy metals from e-waste were present in the surrounding.•The four kind of heavy metals (Cu, Pb, Cd and Cr) attracted more attention.•The exceedance of various standards imposed negative effects to the environment.As the world’s leading manufacturing country, China has become the largest dumping ground for e-waste, resulting in serious pollution of heavy metals in China. This study reviews recent studies on environmental effects of heavy metals from the e-waste recycling sites in China, especially Taizhou, Guiyu, and Longtang. The intensive uncontrolled processing of e-waste in China has resulted in the release of large amounts of heavy metals in the local environment, and caused high concentrations of metals to be present in the surrounding air, dust, soils, sediments and plants. Though the pollution of many heavy metals was investigated in the relevant researches, the four kinds of heavy metals (Cu, Pb, Cd and Cr) from e-waste recycling processes attracted more attention. The exceedance of various national and international standards imposed negative effects to the environment, which made the local residents face with the serious heavy metal exposure. In order to protect the environment and human health, there is an urgent need to control and monitor the informal e-waste recycling operations.

If we consider Waste Electrical and Electronic Equipment (WEEE) management, we can see the development of different positions in developed and developing countries. This development started with the movement of WEEE from developed countries to the developing countries. However, when the consequences for health and the environment were observed, some developing countries introduced a ban on the import of this kind of waste under the umbrella of the Basel Convention, while some developed countries have been considering a regional or global WEEE recycling approach. This paper explores the current movements between Source and Destination countries, or the importers and exporters, and examines whether it is legal and why illegal traffic is still rife; how global initiatives could support a global WEEE management scheme; the recycling characteristics of the source an destination countries and also to ascertain whether the principle of Extended Producer Responsibility (EPR) has been established between the different stakeholders involved in WEEE management.Ultimately, the Full Extended Producer Responsibility is presented as a possible solution because the compensation of the environmental capacity for WEEE recycling or treatment could be made by the contribution of extra responsibility; and also generating an uniform standard for processing WEEE in an environmentally sound manner could support the regional or international solution of WEEE and also improve the performance of the informal sector.Highlights► Source and Destination countries involved in the movement of WEEE have been studied. ► Legislation, facilities and EPR are presented in Source and Destination countries. ► Mostly Destination countries do not have EPR established and have informal facilities. ► Source countries: good technology, EPR established and mostly WEEE regulation enacted. ► Regional WEEE recycling should be under global standards for Sources and Destinations.

Because of their highly effective flame-retardant capability, polybrominated diphenyl ethers (PBDEs) have been extensively used as flame retardants in consumer goods. However, compelling evidence shows that many congeners of PBDEs have been accumulating in the environment, in biota and in human populations worldwide. In China, although octabrominated diphenyl ether (octaBDE) has never been produced or used, pentabrominated diphenyl ether (pentaBDE) and decabrominated diphenyl ether (decaBDE) have been produced and used in large quantities. In the face of increasing evidence about PBDE pollution and the adoption of international conventions, there is a growing push for China to develop more stringent methods of managing PBDE waste. This paper summarizes the information about PBDE production and application, describes the flame-retarding mechanism, and then reviews the toxicity and levels of PBDEs in China's environmental media and human tissues. Based on international regulations on PBDEs, the paper finally puts forward some suggestions for Chinese policy making and for self-regulation within the flame retardant industry.Highlights► The international regulatory systems related to PBDEs are summarized. ► The production and usage information on commercial PBDEs in China is surveyed. ► The flame retardant mechanism and toxicity of PBDEs are summarized. ► PBDE contamination level in China is summarized and compared with that in other countries. ► Three suggestions for Chinese regulations are put forward.

With the accelerating process of urbanization, the amount of municipal solid waste (MSW) generation increases continuously. Landfill occupies a lot of land resources, leading several cities run into a condition being surrounded by MSW. In recent years, MSW incineration rises gradually. Incineration can reduce the MSW volume by 85%∼90% and the mass by about 80%, and incineration with energy recovery is one of the several waste-to-energy (WtE) technologies [1–3]. However, municipal solid waste incineration fly ash, byproducts of MSW incineration, contains large amounts of heavy metals and dioxins, improper disposal will cause serious environmental and human health hazards. This review summarizes the MSW incineration fly ash management system and related policies and regulations in United States, as well as the main disposal methods and utilization technology, in order to provide reference for the management of MSW incineration fly ash in China.

Increasing public attention has been brought to bear on the solid waste management in Macau, due to the continually increasing generation amount and the limited space. In this study, we discussed residents’ attitudes and willingness to pay for solid waste recycling through a questionnaire survey. The results showed that Macau residents owned the relatively good environmental awareness. In regard to Macau environmental quality, most respondents (92.4%) expressed their satisfactions on current situation. About 50.2% respondents thought that the solid waste pollution in Macau was more serious than other three environmental pollutions. The survey data revealed a positive attitude towards source separation in Macau. Most of respondents (95.7%) were willing to sort the solid waste at home, if the government required them to do it. In addition, for the question how to improve the solid waste recycling in Macau, “enhancing residents’ environmental awareness”was considered as the most effective methods, accounting for about 38.5% respondents. In our study, most respondents (85.4%) also provided positive answers to the questions about WTP. Using the logistic regression method, these survey results support the hypothesis that the probability of the respondents’ saying ‘yes’ to the WTP question increases with education level. The monthly mean WTP was 38.5 MOP per household and the annual WTP was approximately 79.7 million MOP for all of Macau. The results can be useful for understanding the residents’ attitudes and WTP for solid waste disposal, for the policymakers and managers, and can be used to promote the recycling of solid waste in Macau.

The current replacement of electronic products is speeding up, resulting in a growing number of e-waste. Electronic waste, especially waste print circuit boards contain large amounts of copper, which not only bring greater ecological threat, but also cause a serious waste of copper resources. Therefore, the study on clean, effective copper leaching technology has a very important practical significance to reduce environmental hazards of waste print circuit board and resources recycling. Hydrometallurgical is a better technology for recycling copper from waste print circuit boards. In this article, hydrometallurgical copper recovery system is divided into four categories: acid leaching, ammonia - ammonium leaching, chloride leaching, as well as other ways of leaching. The advantages and disadvantages of leaching of copper system are analyzed in the process of copper resource utilization. Studies abound on recycling copper from copper-containing waste with citric acid and other complexing agents as the leaching reagent, but studies on recycling copper from waste print circuit boards are rarely reported, which can be used for reference. The trends of the research are using environmentally friendly reagent as leaching agent, selecting the appropriate leaching solution at a certain temperature and pressure and optimizing the subsequent separation procedure. Recycling of waste gas and waste leachate generated in the hydrometallurgical processcan further reduce chemical costs and meet increasingly exacting environmental requirements.

The management of used Cathode rays tube (CRT) devices is a major problem worldwide due to rapid uptake of the technology and early obsolescence of CRT devices, which is considered an environment hazard if disposed improperly. Previously, their production has grown in step with computer and television demand but later on with rapid technological change; TVs and computer screens has been replaced by new products such as Liquid Crystal Displays (LCDs) and Plasma Display Panel (PDPs). This change creates a large volume of waste stream of obsolete CRTs waste in developed countries and developing countries will become major CRTs waste producers in the forthcoming decades. This article provides a concise overview of world's current CRTs waste scenario, namely magnitude of the demand and processing, current disposal and recycling operations.

For waste electrical and electronic equipment (WEEE), large quantities of waste printed circuit boards (PCBs) are released into environment. In light of their characteristics including complex structures, high metals content and potential hazards, waste PCBs are regarded as the most difficult parts of WEEE to be recycled. Therefore in recent ten years, the issue has attracted much attention from researchers and enterprises. This article reviews the latest processes of waste PCBs developed from laboratories to pilot engineering applications, and presents the most suitable available technology for waste PCBs, typically categorized as manually dismantling and automatic approaches in developing and developed countries, respectively. Towards achieving the better sustainability and recyclability for waste PCBs, nonmetal powder and precious metals should be developed for a deep recovery following mechanical treatment. Additionally, a significant shift is emerging from dismantling for recycling of printed wiring boards, to disassembling for remanufacturing of electronic components, which will indicate that a new paradigm of reclaiming waste PCBs is shaping.

The environmental safety of soil has become severe in China with the boost of industrialization and urbanization. In this paper, on the basis of investigating the status of soil contaminated in China, the remediation technologies of soil contaminated by heavy metals, including physical remediation, chemical remediation and biological remediation were focused. The mechanisms of remediation, strengths and drawbacks, developing trend were reviewed in order to supply reference to the study in this field.

With the introduction of LCD technologies, there is almost no demand for new CRTs worldwide. Other alternative recycling outlets are needed, but still waiting to be explored. The author suggests in China recycling of scrap cathode ray (CRT) glass to leaded fluorescent lamp glass is the best industrially available way, but ultimately all the leaded glass may need extracting glass by metallurgy as the progress of the lead free process.

The factors was studied in this article that are the size of the screen mesh, feed quantity and the mechanical property of PWB, which influence particle size distribution of printed wiring board (PWB) crushing product. The size of the screen mesh is the most critical factor while feeding quantity and the mechanical property of PWB influence particle size distribution by changing the pass probability of the crushing product.

Two kinds of BFRs in three WEEE plastics(cell phone shells, computer housings and TV housings) and PCBs were detected with GC/MS. The results showed the plastics used as mobile phone shells had no BFRs. TBBPA was only found in computer housings. Among PBDEs, congeners of heptabromodiphenyl ether, octabromodiphenyl ether and nonabromodiphenyl ether were frequent ones, and detected in both TV housings and computer housings. But the contents of N9BDE were lower than the other two, only 180 mg/kg and 5.3 mg/kg in computer housings and TV housings respectively, while pentabromodiphenyl ether and hexabromodiphenyl ether were determined in PCBs.

The progress in current research in and abroad on recycling and reuse of nonmetallic materials from waste circuit boards was introduced, and technical principle and research situation of tradition techniques adopted for resource modification, including energy recovery techniques, solution recovery techniques, supercritical techniques, physical recovery techniques and pyrolysis techniques were discussed in details in this paper. And finally, it is concluded that comprehensive use of various methods is the tendency for recycling non-materials from waste circuit boards after exploring disadvantages and advantages of these five approaches.

With the development of the science, technology and economy, electronic products became the important necessary products in daily life. Due to the large usage of electronic products, generation of the e-waste became more and more. The e-waste treatment was generally as a troublesome task. The life cycle assessment (LCA) method is used to analyze the treatment technology of cathode ray tube (CRT) display. The results show that the environmental impact of incineration of CRT display has the greatest impacts, with comparison to the manual-based dismantling and mechanical recycling. The impact of Carcinogens is the major contributor, which cause a direct impact on human health. The result suggests that the CRT display should be separately treated and not be mixed with municipal solid waste which is treated by incineration.

•Lead demand has strained the sustainability of China’s lead reserve.•The carrying duration of lead resource until 2030 will oblige the recycling rate to grow at above 90%.•Future management measures should include optimizing lead industrial structure and development of new energy.Lead is not only one of heavy metals imposing environment and health risk, but also critical resource to maintain sustainable development of many industries. Recently, due to the shortage of fossil fuels, clean energy vehicles, including electric bicycle, have emerged and are widely adopted soon in the world. China became the world’s largest producer of primary lead and a very significant consumer in the past decade, which has strained the supplies of China’s lead deposits from lithosphere and boost the anthropogenic consumption of metallic lead and lead products. Here we summarize that China’s lead demand will continually increase due to the rapid growth of electric vehicle, resulting in a short carrying duration of lead even with full lead recycling. With these applications increasing at an annual rate of 2%, the carrying duration of lead resource until 2030 will oblige that recycling rate should be not less than 90%. To sustain lead utilization in China, one approach would be to improve the utilization technology, collection system and recycling technology towards closed-loop supply chain. Other future endeavors should include optimizing lead industrial structure and development of new energy.The relationship between the increasing rate of lead demand and recycling rate of waste.Download high-res image (118KB)Download full-size image

In the context of huge imbalance between increasing demand for metals and the finiteness of metal resources in nature, recycling metal from second-hand resources, especially e-waste, is of great importance, to embrace the sustainability challenge. Inspired by its hundreds of uses in extractive metallurgy, mechanochemistry has been introduced to recover metals from waste since the 1990s. The mechanochemical recycling process is technically feasible to recover metals from waste in a high yield, such as Pb recovery from cathode ray tube (CRT) funnel glass, Li and Co recovery from lithium-ion batteries, rare earth recovery from fluorescent lamps. In recovery from LCD screens, Cu recovery from waste printed circuit boards and Au, Mo and Ni recovery from waste. Particle size reduction, specific surface area increase, crystalline structure decomposition and bond breakage have been identified as the main changes induced by the mechanochemical processes in the studies. Also, the activation energy required decreases and reaction activity increases, subsequently. This paper presents a technical overview of the applications of mechanochemistry to metal recycling from waste. The current application pattern, reaction mechanisms, equipment used, method procedures, and the future research direction are discussed in detail. This work presents the limitation of current mechanochemical application in metal recovery and gives a perspective of the future development of mechanochemistry as well.