AIST Stories No2
18From AIST to the Innovative Worldat a glanceTerminologyHow can rare metals be separated from crushed components?Japan boasts meager natural resources and has been reliant on imports for the vast majority of its requirements. In addition to the emerging possibility that Japan could become a country possessing energy resources on account of the methane hydrates that exist in neighboring waters, there is in fact one more major resource that exists: urban mines.Urban mines are the valuable resources contained in discarded products such as consumer electronic products. One can anticipate an intelligent material cycle if these resources are recovered and reused through recycling. Having said so, “mining” is by no means easy. The target is trace quantities of metal used on the printed circuit boards of discarded consumer electronic products; in contrast to natural mines where resources are concentrated, these resources are spread thinly throughout the whole of Japan. This represents the key challenge. Moreover, to begin with, the majority of rare metals cannot be recovered using standard recycling methods employed in smelters to process copper and other precious metals.Research Group Leader Tatsuya Oki who handled A world-leading recycling technology from AISTHigh-efficiency recovery of a rare metal from “urban mines”The rare metal tantalum “mined” from electronic devicesAdvanced Recycling Technology Research Group, Research Institute for Environmental Management TechnologyDouble tube pneumatic separator●Procedure for separating rare metals using a double tube pneumatic separator (1) Only fragments measuring 2–5 mm are separated from the pieces of crushed components and circuit boards. After sorting in an inclined and low-intensity magnetic shape separator, they are carried to the double tube pneumatic separator. (2) Particles with high specific gravity fall in the No. 1 Column with high air velocity and are recovered. (3) Particles with intermediate specific gravity fall in the No. 2 Column with intermediate air velocity and are recovered and sorted from the floating particles with low specific gravity.In this manner, sorting is carried out based on specific gravity by using various airflow velocities.Low specific gravity particles High specific gravity particlesIntermediate specific gravity particlesRare metals have been discarded along with the electronic devices because there was no way of recycling them. However if AIST technology can be deployed to recover these metals with high efficiency for subsequent reuse, Japan will no longer have to rely entirely on the import of rare metals that are indispensable for electronic devices. Furthermore, if this world-leading technology can be exported, then the result will be not only economic stimulus, but also a contribution to global environmental protection.ControlpanelDatabase-assistedautomatic controlAirflowColumn 2Low air velocityLow specificgravity particlesHigh specific gravity particlesBlowerContinuous feederAirFlat cross-sectionalair velocityColumnColumnCoupling tubeAirCross-sectional air velocityin pipe of this equipmentConventional cross-sectionalair velocity in pipeFastSlowIntermediatespecific gravityparticlesIntermediatespecific gravityparticlesFast air velocityColumn 1Into the futureAIST!Our life and society will change in this way!