WEEE中の金属リサイクルに関する研究

金属含有量インベントリ作成のための調査 2

抄録

Hard disk drive (HDD) is a major device in information appliances. Market of HDD has expanded for over 10 years. Though many kinds of metal are used in HDD, especially some minor metal in printed circuit board (PCB) and rare-earth elements in voice coil motor (VCM) magnet, they haven't been recycled enough. In order to gain basic information of recycling of end-of-life HDD, inventory of HDD has been investigated by measuring weight and metal content of PCB and rare-earth magnet in HDD. Weight of PCB and VCM magnet has decreased gradually by improvement of technology of PCB design and magnetic materials, nevertheless disassembling efficiency hasn't been improved for 10 years because of few change in basic structure of HDD. It was shown that contents of some minor metals (Ta and Pd) and harmful elements (Pb, Sb, Br) in PCB have decreased because of their rising value or material regulations such as RoHS. Content of Nd, Pr, Tb and Dy in VCM magnet was investigated by chemical analysis. Although only dysprosium was mainly used till 2000 for the improvement in coercivity of a magnet, Tb has also come to be used as an alternative element in 2001 and afterwards. It was suggested by calculation that magnet of 1,492ton and PCB of 4,012ton remain at 2008 as the in-use stock in Japan. It is desired to improve the structure of collection and pretreatment process of end-of-life HDD.