WEEE recovery strategies and the WEEE treatment status in China

The electric and electronic equipment has been developed, applied, and consumed world wide at a very high speed. Subsequently, the ever-increasing amount of waste electric and electronic equipment (WEEE) has become a common problem facing the world. In view of the deleterious effects of WEEE on the environment and the valuable materials that can be reused in them, legislations in many countries have focused their attention on the management of WEEE, and new techniques have been developed for the recovery of WEEE. In China, rapid economic growth, coupled with urbanization and growing demand for consumer goods, has increased the consumption of EEE in large quantity, thus made the WEEE manifold rapidly, posing a severe threat to the environment and the sustainable economic growth as well. This article reviewed the implementation of strategies of WEEE treatment and the recovery technologies of WEEE. It presented the current status of WEEE and corresponding responses adopted so far in China. The concept and implementation of scientific development is critical to the sector of electronics, one of the important industrial sectors in China's economy. To achieve this objective, it is significant to recycle WEEE sufficiently to comply with regulations regarding WEEE management, and to implement green design and cleaner production concepts within the electronics industry to comply with the upcoming EU and China legislation in a proactive manner.     

A new two-roll electrostatic separator for recycling of metals and nonmetals from waste printed circuit board

The electrostatic separation is an effective method for recycling waste electrical and electronic equipment (WEEE). The efficiency of electrostatic separation processes depends on the ability of the separator. As a classical one, the roll-type corona-electrostatic separator has some advantages in recycling metals and plastics from waste printed circuit board (PCB). However, its industry application still faces some problems, such as: the further disposal of the middling products of the separation process; the balance of the production capacity and the good separation efficiency; the separation of the fine granular mixture and the stability of the separation process. A new "two-roll-type corona-electrostatic separator" was built to overcome the limitation of the classical one. The experimental data were discussed and the results showed that the outcome of the separation process was improved by using the new separator. Compared with the classical machine, the mass of conductive products increases 8.9% (groups 2 and 3) and10.2% (group 4) while the mass of the middling products decreases 45% (groups 2 and 3) and 31.7% (group 4), respectively. The production capacity of the new machine increases, and the stability of the separation process is enhanced.     

电子废弃物资源化处理现状

伴随着信息技术的高速发展,电子废弃物的种类和总量日益增多,它具有数量多、危害大、潜在价值高、回收利用困难等特点。本文中分析了火法处理、湿法处理、机械处理、热裂解等电子废弃物资源化处理技术,并指出了不同技术的优缺点,重点介绍了机械处理、湿法处理及热裂解处理方法工艺特点,同时对最新研究进展作了简要评述和展望。     

废旧印刷电路板中电子元器件回收处理技术进展

电子元器件广泛应用于电子电器设备中,但由于产品更新换代和电子电器产业市场的膨胀,大量的电子元器件被丢弃。对电子元器件的资源性和危害性进行分析,综合评述了电子元器件回收利用的最新研究进展和成果,主要包括电子元器件的拆卸技术(解锡方法和分离方法)和回收技术。在此基础上,提出了废旧印刷电路板中电子元器件的无害化和资源化回收研究新动向及发展建议。     

Treatment and recycling system optimisation with activity-based costing in WEEE reverse logistics management: an environmental supply chain perspective

Waste electrical and electronic equipment (WEEE) reverse logistics management has increasingly received much attention in recent years not only because of the fast increase of WEEE but also the legislations in many developed countries. This paper focuses on the treatment and recycling system, and proposes a two-stage multi-objective decision framework. In the treatment stage, the responsible producer selects treatment suppliers under extended producer responsibility by a pre-emptive goal programming model. After the wastes are depolluted and transformed to recyclable materials, the process enters the recycling stage in which the decision-maker plans the reclaimed material production by a linear programming model for profit maximisation. An illustrative case study is presented, and the sensitivity analyses show that the ranking of suppliers is more stable than the quantities allocated to suppliers under different priority structures, so ranking of suppliers should also be given attention in such multi-objective decision-making. In addition, a decision model with environmental constraints can reduce the production of the products that have more environmental impacts.     

Optimization of key factors of the electrostatic separation for crushed PCB wastes using roll-type separator

For the electrostatic separation process, the separator is most crucial. As a classical one, the roll-type corona-electrostatic separator has some advantages in recycle of waste electrical and electronic equipment (WEEE). Some researches have been done in this field and shown that there was a complex correlation between its configuration and the efficiency of the separation. In this paper, a fractional factorial design (2v1-5) was built and 32 tests were performed on a roll-type corona-electrostatic separator. The sample of granular mixture got from crushed PCB wastes (size 0.3-0.45 mm, containing 25% metal and 75% nonmetal). The experimental data were discussed and used to analyze the factors' main effect, interaction and optimization of the process. Three liner-interaction mathematical models were derived to describe the mass of middling fraction (M), conductor fraction (C) and Nonconductor fraction (NC), respectively. The results show that the efficiency of the PCB waste electrostatic separation process has a significant correlation with not only factors' main effects, but also the interaction between them.     

Recycling of waste printed circuit boards: a review of current technologies and treatment status in China

From the use of renewable resources and environmental protection viewpoints, recycling of waste printed circuit boards (PCBs) receives wide concerns as the amounts of scrap PCBs increases dramatically. However, treatment for waste PCBs is a challenge due to the fact that PCBs are diverse and complex in terms of materials and components makeup as well as the original equipment's manufacturing processes. Recycle technology for waste PCBs in China is still immature. Previous studies focused on metals recovery, but resource utilization for nonmetals and further separation of the mixed metals are relatively fewer. Therefore, it is urgent to develop a proper recycle technology for waste PCBs. In this paper, current status of waste PCBs treatment in China was introduced, and several recycle technologies were analyzed. Some advices against the existing problems during recycling process were presented. Based on circular economy concept in China and complete recycling and resource utilization for all materials, a new environmental-friendly integrated recycling process with no pollution and high efficiency for waste PCBs was provided and discussed in detail.     

Milling and Classification of Printed Circuit Boards for Material Recycling

Recycling of waste electric and electronic equipment (WEEE) is an emerging issue due to its hazardous nature. It is important to identify an appropriate environment-friendly process to recover the valuables and for safe disposal. The present work deals with the two-stage crushing process followed by a circulating air classifier for the separation of metals and nonmetals from the printed circuit boards (PCB). The two-stage crushing process is deployed to liberate the valuables for an appropriate progeny size distribution. The metal content decreases as the particle size decreases below 0.5 mm. However, it increases metal content above 500 µm up to 1,800 µm. It is concluded that the metals primarily enriched in the size range of ?1.8 + 0.5 mm. The amount of metals and plastics present in each fraction is estimated. Among the classifier parameters, air flow velocity played a dominant role in metal enrichment. The material feed rate and rotating guide vane angle have no a significant effect on the enrichment of metals and nonmetals. The air flow velocity found was to be one of the crucial parameters for enrichment of metals. The superficial air flow velocity is optimized for efficient separation of metals and nonmetals of PCBs.     

Integrated planning of acquisition,disassembly and bulk recycling: a case study on electronic scrap recovery

Abstract. Due to national and supranational legislation activities, the recovery of discarded products will attain an increasing momentum. Electronic equipment consists of many different parts and materials. Therefore, the related recovery process is often divided into disassembly to remove harmful substances or reusable parts and into bulk recycling to recover ferrous and non-ferrous metals. In order to consider the interactions between choice of scrap to be recovered (acquisition problem), disassembly and bulk recycling, a mixed-integer linear programming model for integrated planning of these stages is presented in this case study. It is applied to determine the daily allocation of products to processes for a major electronic scrap recovery centre that faces limited processing capacities and market restrictions. The optimization calculations covering typical discarded electronic products to be recycled in the related centre lead to a relevant improvement of the economic success. RID="*" ID="*" The authors would like to thank the German “Bundesministerium für Bildung und Forschung” (Federal Ministry of Education and Research) for supporting the research project “Substance Flow Oriented Closed Loop Supply Chain Management in the Electrical and Electronic Equipment Industry (STREAM)rdquo;. Correspondence to: T. Spengler     

Assessment of removal of components containing hazardous substances from small WEEE in Austria

Minimum treatment requirements for waste electrical and electronic equipment (WEEE) established by Directive 2002/96/EC provide for the removal of specific components containing hazardous substances. To date, no comparative analysis of removal rates has been undertaken. The present paper examines the state of de-pollution of sWEEE in Austrian treatment plants. The mass of selected components removed and the corresponding mass of hazardous substances is compared to estimated values for sWEEE input material. The results obtained reveal that components are only partly removed, featuring a high variation between components and plants assessed. The overall rate of removal ranged from 72% of the estimated value for batteries to 21% of the estimated value for liquid crystal panels. This implies the forwarding of substantial quantities of hazardous substances to mechanical treatment processes, particularly relevant in terms of dispersion of pollutants. Furthermore, easily releasable pollutants, such as Hg from LCD-backlights, Cd from batteries or highly contaminated dust in general, pose substantial health risks for plant workers. Low removal rates of printed circuit boards, batteries and toner cartridges also lead to a reduction in quantities of valuable recyclable materials (precious metals, plastics).     

政府规制对电器电子产品闭环供应链决策的影响分析

为了分析政府规制对采用不同回收模式的电器电子产品闭环供应链(CLSC)决策的影响,在政府规制和无政府规制两种情形下,分别建立了制造商回收模式、销售商回收模式以及第三方回收企业回收模式的电器电子产品闭环供应链决策模型。通过对比政府规制前后不同回收模式下CLSC各成员的最优决策和收益,发现无论政府规制与否,只要制造商的单位回收成本不是非常高,制造商回收模式都对它自身更有利,否则制造商最好将回收活动外包给销售商。而销售商和第三方回收企业都希望自己从事回收活动。此外,政府规制下销售商回收模式对全社会更有利。     

废旧高分子材料回收利用的进展

概述了目前高分子材料的回收利用情况,在列举原有废旧聚合物回收途径的同时,详细说明了废旧聚合物回收利用的新进展,如生物侵蚀法回收废橡胶．回收橡胶与热塑性塑料的共混体,废胶粉粒子添加到水泥中,热解废塑料,塑料“再生木材”,废塑料和玻璃复合商用砖等等。     

Effect of particle size composition on the separation of waste printed circuit boards by vibrated gas–solid fluidized bed

The mechanism of fine particles on the separation of waste printed circuit boards by vibrated fluidized bed is not clear. In this paper, the influence of particle composition on fluidization behavior and separation characteristics of waste printed circuit boards particles was studied. The separation results showed that the increase of fine particles significantly reduced the metal recovery. When the content of fine particles was 20 %, the concentrate yield decreased by 11.26 % and the metal recovery declined by 15.93 %. The analysis of fluidization characteristics proved that the stability of the bed was reduced at higher fine particle content. When the content of fine particles was 20 %, the standard deviation of bed pressure drop was 34.15 Pa higher than that without fine particles. And the microscopic and X-ray fluorescence analysis confirmed that the adhesion behavior of fine particles prevented them from being separated by density. In addition, it was found that the pre-removal of iron and aluminum could effectively improve the separation performance with a fine particle content of 20 %, and the metal recovery increased by 6.29 %. Based on this, our findings will provide important guidance for efficient recovery of valuable metals from waste printed circuit boards.     

A PSO-based optimum consumer incentive policy for WEEE incorporating reliability of components

The world is going digital, human infatuation with gadgets is increasing and a very short product lifecycle of these products has resulted in a horrendous threat to the environment. Waste electrical and electronic equipment (WEEE) reverse logistic management has been a key area for researchers to innovate and produce insights that could sustain businesses without compromising the environment. In this paper, we aim to understand the consumer return behaviour of end of life goods at different incentive levels and make an attempt to incorporate the latest research practices. A novel attempt is made in this paper, where we have for the first time applied product and component reliability in determining the incentives given to the consumer so that the efforts of WEEE recycling and disposal could be conducted in an economically sustainable manner to promote ecological sustainability, thereby envisaging upon the fact that there is a hidden synergy between the trade and environment, and only innovative managerial approaches that are thoroughly pragmatic, could exploit them. The optimisation model has been solved using particle swarm optimisation (PSO) and the insights produce highlight upon the feasibility of such a model.     

Optimizing the operating parameters of corona electrostatic separation for recycling waste scraped printed circuit boards by computer simulation of electric field

The printed circuit board (PCB) has a metal content of nearly 28% metal, including an abundance of nonferrous metals such as copper, lead, and tin. The purity of precious metals in PCBs is more than 10 times that of rich-content minerals. Therefore, the recycling of PCBs is an important subject, not only from the viewpoint of waste treatment, but also with respect to the recovery of valuable materials. Compared with traditional process the corona electrostatic separation (CES) had no waste water or gas during the process and it had high productivity with a low-energy cost. In this paper, the roll-type corona electrostatic separator was used to separate metals and nonmetals from scraped waste PCBs. The software MATLAB was used to simulate the distribution of electric field in separating space. It was found that, the variations of parameters of electrodes and applied voltages directly influenced the distribution of electric field. Through the correlation of simulated and experimental results, the good separation results were got under the optimized operating parameter: U=20-30 kV, L=L(1)=L(2)=0.21 m, R(1)=0.114, R(2)=0.019 m, theta(1)=20 degrees and theta(2)=60 degrees .     

一种可拆卸回收的快递包装箱结构设计研究

目的 促进快递包装的重复利用,提高废弃快递包装的回收率,从源头改善快递包装的浪费和对环境的污染,在不影响产品保护的同时推动绿色包装的发展。方法 深入分析当前快递包装回收业务中存在的问题,探索如何应用可拆卸设计方法对快递包装箱的结构进行设计,研究如何对快递包装箱进行伸缩调节,以适应不同产品的运输要求,并优化拆卸、更换和组装的工序,摒除当前包装整体废弃的弊端,实现局部回收,提高快递包装的利用率。结果 该可拆卸包装箱在组装、开启、拆卸、收纳等过程中操作方便,在实操测试中用较短的时间即可完成上述工序,并在抗摔测试中能经受住装载与运输过程中的外力碰撞,能对产品起到良好的保护作用。结论 利用可拆卸设计方法对快递包装箱进行结构设计,能方便地对损坏的包装部件进行更换,能有效减少包装废弃物的产生,具有便利性、兼容性与安全性,有利于建立高效通畅的回收与再用系统,减少对资源的浪费和环境的污染,在生态保护与绿色发展等方面具有积极的意义。     

Metallurgical recovery of metals from electronic waste: a review

Waste electric and electronic equipment, or electronic waste, has been taken into consideration not only by the government but also by the public due to their hazardous material contents. In the detailed literature survey, value distributions for different electronic waste samples were calculated. It is showed that the major economic driver for recycling of electronic waste is from the recovery of precious metals. The state of the art in recovery of precious metals from electronic waste by pyrometallurgical processing, hydrometallurgical processing, and biometallurgical processing are highlighted in the paper. Pyrometallurgical processing has been a traditional technology for recovery of precious metals from waste electronic equipment. However, state-of-the-art smelters are highly depended on investments. Recent research on recovery of energy from PC waste gives an example for using plastics in this waste stream. It indicates that thermal processing provides a feasible approach for recovery of energy from electronic waste if a comprehensive emission control system is installed. In the last decade, attentions have been removed from pyrometallurgical process to hydrometallurgical process for recovery of metals from electronic waste. In the paper, hydrometallurgical processing techniques including cyanide leaching, halide leaching, thiourea leaching, and thiosulfate leaching of precious metals are detailed. In order to develop an environmentally friendly technique for recovery of precious metals from electronic scrap, a critical comparison of main leaching methods is analyzed for both economic feasibility and environmental impact. It is believed that biotechnology has been one of the most promising technologies in metallurgical processing. Bioleaching has been used for recovery of precious metals and copper from ores for many years. However, limited research was carried out on the bioleaching of metals from electronic waste. In the review, initial researches on the topic are presented. In addition, mechanisms and models of biosorption of precious metal ions from solutions are discussed.     

Theoretic model and computer simulation of separating mixture metal particles from waste printed circuit board by electrostatic separator

Traditionally, the mixture metals from waste printed circuit board (PCB) were sent to the smelt factory to refine pure copper. Some valuable metals (aluminum, zinc and tin) with low content in PCB were lost during smelt. A new method which used roll-type electrostatic separator (RES) to recovery low content metals in waste PCB was presented in this study. The theoretic model which was established from computing electric field and the analysis of forces on the particles was used to write a program by MATLAB language. The program was design to simulate the process of separating mixture metal particles. Electrical, material and mechanical factors were analyzed to optimize the operating parameters of separator. The experiment results of separating copper and aluminum particles by RES had a good agreement with computer simulation results. The model could be used to simulate separating other metal (tin, zinc, etc.) particles during the process of recycling waste PCBs by RES.     

A model for simulating the grinding and classification cyclic system of waste PCBs recycling production line

Crushing and separating technology is widely used in waste printed circuit boards (PCBs) recycling process. A set of automatic line without negative impact to environment for recycling waste PCBs was applied in industry scale. Crushed waste PCBs particles grinding and classification cyclic system is the most important part of the automatic production line, and it decides the efficiency of the whole production line. In this paper, a model for computing the process of the system was established, and matrix analysis method was adopted. The result showed that good agreement can be achieved between the simulation model and the actual production line, and the system is anti-jamming. This model possibly provides a basis for the automatic process control of waste PCBs production line. With this model, many engineering problems can be reduced, such as metals and nonmetals insufficient dissociation, particles over-pulverizing, incomplete comminuting, material plugging and equipment fever.     

Integrated approach for disassembly processes generation and recycling evaluation of an end-of-life product

An integrated approach for noble recycling is presented that puts forward the functional value of products and components. In a first step, the approach determines all feasible automatic disassembly sequences and in a second step all applicable recycling activities. This allows one to determine the most appropriate recycling process for an end-of-life product considering concurrent recycling techniques. The feasible automatic disassembly sequences are established by simulation in a virtual environment. The required generic disassembly product model, as well as the generic disassembly activity model, is presented by means of static and dynamic object-oriented diagrams. The recycling evaluation establishes an efficient solution responding to economic and ecological decision criteria. It is calculated applying a Goal-Programming approach transforming the multi-objective linear problem into a monocriteria linear program. The techno-economic decision model applied is Linear Activity Analysis. It allows one to integrate the generated disassembly processes based on single disassembly activities as well as other recycling techniques.