《循环经济（英文）》（Circular Economy）Volume 1, Issue 2
Circular Economy （ISSN: 2773-1685; e-ISSN: 2773-1677）
This issue is a Special Issue focused on Urban Mining, presenting recycling technology and methodology for waste electrical and electronic equipment (WEEE), end-of-life lithium-ion batteries (LIBs), and other metallic products. The following are our Guest Editors for this issue.
Prof. Mengjun Chen
Organization: Southwest University of Science and Technology, Key Laboratory of Solid Waste Treatment and Resource Recycle
Prof. Jingwei Wang
Organization: Shanghai Polytechnic University, Shanghai Collaborative Innovation Centre for WEEE Recycling
编者按（Editorial）
Urban mining is an essential approach to circular economy and plays the roles of urban waste recycling and environmental impact reducing. It has been attached tremendous attention in recent years due to worldwide campaigns for climate change and sustainable development. In order to make its role to the full potential, some countries or organizations enact or update relevant regulations and meanwhile enhance the R&D of urban mining. As the result of reflection of latest R&D in the core area of urban mining, this special issue of the Journal of Circular Economy presents recycling technology and methodology for waste electrical and electronic equipment (WEEE), end-of-life lithium ion battery (LIBs), and other metallic products.
综述性论文（Reviews）
1、Recycling spent lithium-ion batteries using a mechanochemical approach
Mengmeng Wang, Kang Liu, Jiadong Yu, Congcong Zhang, Zhiyuan Zhang, Quanyin Tan
Under the vision of achieving the SDGs and mitigating climate change, the electric vehicles (EVs) industry is evolving rapidly, leading to a proliferation of spent lithium-ion batteries (LIBs). The efficiently recycling of LIBs, especially, the critical energy metals like Li, Co, Ni, and Mn etc., is essential to the sustainable development of the EV industry, which is consistent with the concept of circular economy. In this regard, the green extraction of metals is the core and bottleneck of recycling. As an alternative to traditional pyrometallurgy and hydrometallurgy, emerging mechanochemical technology provides a new approach for efficient and green recycling of critical metals from spent LIBs, as it has the advantages of easy operation, flexibility, and short processing time. This article systematically reviews the state of the art of studies on and application of mechanochemical technology in the recycling of critical metals from spent LIBs. Based on numerous practices, a framework including mechanochemical activation, organic reaction, inorganic reaction, redox reaction, gas-solid reaction, and solid-phase synthesis was constructed. These practices have proved that mechanochemical technology can provide a greener and more sustainable solution for recycling the critical metals from spent LIBs. So far, an application system has been built and is evolving with the continuous extension of research. Therefore, mechanochemical technology has broad prospects and application potential for the green recycling of critical metals from spent LIBs.
2、State-of-the-art lithium-ion battery recycling technologies
Muammer Kaya
The global demand for lithium-ion batteries (LIBs) for portable electronic devices and electrical vehicles (EVs) have risen sharply, and the global amount of spent LIBs (s-LIBS) is increasing proportionally. S-LIBs contain not only dangerous heavy metals but also toxic chemicals that pose a serious threat to ecosystems and human health. The current situation makes the recycling of S-LIBs indispensable for the protection of the environment and the recycling of scarce raw materials (Li, Co, Ni, Mn, and Al) used in the LIBs from economic aspects.
In this paper, the state-of-the-art processes for metal recycling from S-LIBs are reviewed, the structure of a LIB are introduced, and all available technologies that are used in different recovery processes are summarized and compared. It is notable that pretreatment, metal extraction, and product preparation play important roles in the whole recovery process, based on one or more of the principles of pyrometallurgy, hydrometallurgy, biometallurgy, and mechanical treatment, and water leaching. The pretreatment process in S-LIB recycling can enhance the recovery efficiency of the valuable elements in the LIBs and significantly reduce energy consumption in subsequent processes. Industrial applications of LIB recycling are also covered shortly in this study. By further comparing different recycling methods, existing challenges are identified and suggestions for improving the recycling effectiveness can be proposed.
3、End-of-life management of electric and electronic equipment: A literature review based on mapping knowledge domains
Jie Li, Shidi Zhang, Yanan Jiang
- To tackle the challenges in the end-of-life management of e-waste, a systematic review was undertaken using a visualized approach
- 8149 research articles were exported from the database and then analyzed based on mapping knowledge domains
- CiteSpace and Gephi, as effective tools, were utilized to identify hidden patterns and correlations from large and complex research outcomes
- The evolution of global e-waste management, the knowledge-based network, research topics, frontiers and the cooperation relationships were discussed
- The state-of-the-art review generated a few research directions that can be further investigated in the research field
原创性论文（Articles）
1、Comparative analysis of recycling modes of power batteries based on extended producer-responsibility principle
Shuyuan Chen, Mengjun Chen, Jiancheng Shu, Yi Deng
To improve the effectiveness of recycling, echelon utilization, and recovery mechanism of waste power batteries (WPBs), 12 recycling modes were proposed based on extended producer-responsibility principle. By employing profit and sensitivity analyses, we found that resource-recovery companies (Rs) are the key for recycling, echelon utilization, and recovery mechanism. For R, the high resale price of waste LiNixMnyCo1−x−yO2 batteries was not conducive to recovering waste batteries. However, the recycling behavior of R was beneficial for resisting the risk of high resale price of waste LiNixMnyCo1−x−yO2 batteries. This condition increased the profits by saving on the buying cost and reselling of WPBs to echelon-utilization companies. Following the decrease in the number of recyclers in the recycling system, the profits of R also increased. However, when the proportion of recycled waste LiNixMnyCo1−x−yO2 batteries was 100%, the profits of R faced risks due to the high resale price of waste LiNixMnyCo1−x−yO2 batteries. For other recyclers, only the power-battery manufacturers (Ms) were willing to reduce the resale price of waste LiNixMnyCo1−x−yO2 batteries to let R earn profit because R supplied regenerated materials to M at a lower price than the material companies. This condition created a cycle for WPB recovery and reduced the use of raw materials. Thus, Mode M–R was considered as the optimal recycling mode.
2、Disentangling the worldwide web of e-waste and climate change co-benefits
Narendra Singh, Oladele A. Ogunseitan
Climate change driven by greenhouse gas emissions to the atmosphere has recently emerged as the most serious existential threat to human societies as we now know it. The electronics industry which has enabled transformation of society in many ways also poses a threat in terms of toxic pollution and emissions of greenhouse gases primarily because of the short useful life of consumer electronic products. The industry is currently among the top eight sectors accounting for more than 50% of the global carbon footprint. Moreover, it has been estimated by others that more than two-thirds of greenhouse gas emissions from the industry is attributed to the supply chain including raw materials mining, manufacture, and assembly of electronic components, as well as transportation of the finished product. This study shows that it is possible to slow the carbon footprint of the electronics industry by increasing the useful life of products leading to the reduction of embodied carbon emissions. Specifically, increasing the useful lifespan expectancy of electronic devices by 50%–100% can mitigate up to half of the total greenhouse gas emissions. Such outcomes will require coordination of eco-design, source reduction, and the widespread adoption of repair, refurbishment, and reuse strategies.
3、Metallic product recognition with dual attention and multi-branch residual blocks-based convolutional neural networks
Honggui Han, Qiyu Zhang, Fangyu Li, Yongping Du, Yifan Gue, Yufeng Wu
- For all kinds of waste metallic products, less than 20% of the total amount is recycled globally every year, resulting in a large number of waste metallic products not being disposed of reasonably, which limits the development of circular economy and hinders the formation of closed-loop resource recovery.
- This study constructs a deep convolutional network for metallic product recognition based on multi-branch residual blocks and dual attention mechanism, which is important for the fine-grained recognition part of the metallic product recycling process.
- The waste electrical and electronic equipment (WEEE) dataset and the waste household metal appliance (WHMA) dataset are built, which have sufficient sample size to ensure the generalization ability of the model for metallic product recognition.
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