ارائه روش بازیافت مناسب برای پسماندهای الکترونیکی کوچک Design of a Proper Recycling Process for Small-Sized E-waste

Abstract Recently, small-sized home appliances have been included in the recycling legislations of Japan. However, since small-sized home appliances have many varieties and individual products are small, it won’t be economically feasible to disassemble each e-waste manually. Thus, combinations of pulverization and physical separation technologies are being discussed. This paper applies pulverization plus physical separation for the basic recycling process of used mobile phones. By applying XRF analysis to classified particles, the paper clarifies that valuable material such as copper, silver, etc are more concentrated in printed circuit board (PCB) and relatively larger particles. Based on the result, the paper shows that separation of PCB-origin particles after rough pulverization can be a good strategy for low-cost and high-quality material recycling. Plus, the paper proposes a basic concept of a totally new recycling process so-called “remote separation,” for the future studies. ۱٫ Introduction Electrical and electronic equipment (EEE) are popular in recent world and have large impacts on environment. Recently in Japan, non-recycled products so-called “urban mine [1]” are the targets of discussion. Since the urban mine contains electronic products such as PCs, mobile phones, etc., it is said that considerable amounts of critical metals are being abandoned. Especially for small and medium-sized e-waste, no legislations to promote recycling and circular economy had existed. Because of the smallness, these products are often hibernated or dumped as municipal wastes, after the product life. As a countermeasure to this situation, a new recycling legislation to cover used small and medium sized e-waste has been discussed [2] and started from April, 2013. In the new legislation, recycling fee is not collected from consumers, unlike the large-sized e-waste such as air conditioner, refrigerator, etc. Thus, new social system for recycling should be economically profitable without any subsidy or recycling fee from consumers. Although small-sized e-wastes contain relatively higher concentrations of valuable metals, manual disassembly of such products is very time consuming and will be a cost driver. Therefore, a more automated recycling process than the recycling process of large-sized e-waste will be necessary to promote recycling of small-sized e-waste. The purpose of this paper is to propose a totally new concept for recycling operations which can reduce the cost for recycling of small-sized e-waste drastically, and to collect some fundamental data to discuss the feasibility of the new method. ۲٫ Target product Since there are too many variations of small-sized e-waste, this paper focuses on used mobile phones. Used mobile phones contain valuable metals compared to other small-sized e-waste. (Table 1, Original data from [2].) As shown in the table, most of Nd which can be potentially recovered from small-sized e-waste is contained in used mobile phones. About Pd, W, La and Au, nearly or more than half of the metals contained in small-sized e-waste are contained in used mobile phones. In addition, mobile phones are one of the most common electronic products in Japan and its ownership rate is over 80%. It means that huge amount of used products are currently hibernated in personal homes, and will be emitted from now. Thus, the paper focuses on a process design to enhance recycling efficiency from used mobile phones. ۳٫ Proposal on a remote process for e-waste recycling ۳٫۱٫ The original concept Reducing disassembly cost is one of the keys to improve cost-profit balance of e-waste recycling. Simply, operating manual disassembly processes at locations where labor costs are more inexpensive, will be effective in reducing the recycling cost. However, exporting used products which contain considerable critical metals and rare earths is not welcomed, in the aspect of Japanese resource securing policy. At the same time, outflow of “waste” is restricted by Basel Convention. In the existing paper [3], a basic concept of remote recycling system utilizing tele-operation technologies was proposed as a countermeasure of this problem. The concept was named tele-inverse manufacturing. The feature of the model is that the operations for recycling are carried out via tele-operation. Fig.1 illustrates the basic concept. Suppose that e-waste is located at location B and it is processed at the location. However, in tele-inverse manufacturing, the operators do not stay at the same location. They can stay at a different location and carry out recycling processes by teleoperation.