Abstract:
It is essential to make a concrete system for the stable securement of minor rare metals in electric and electronic industry. The Japanese government has decided to make four kinds of measures of (1) Development of oversea mines, (2) Recycling of e-wastes, (3) Finding out replaceable elements, and (4) Increasing domestic stockpiles. In especial, the (2) has become an emergent issue and "The Low of Small Domestic Appliances recycling" was enforced in April, 2013, in which minor rare metals, such as Ta, Nd, W, and Co, should be recycled from SDAs. However, a novel technology is necessary to be developed because most of such metals are presently not recovered owing to their low market price and most of them are distributed into landfill sites and/or the slags of non-ferrous metals smelters in non-recoverable state. Then, an important technology, consisting in separate these metals before the treatment of the non-ferrous metals smelters, in which only heavy and precious metals, Cu, Au, Ag, Pt, etc. are recovered, must be developed.
This paper introduces a technological approach to recover minor rare metals from scrap SDAs, which was carried out in four year national project managed by the Japan Oil, Gas and Metals National Corporation (JOGMEC), in especial, new concentration methods of such metals by combining novel crushing and various physical separation technologies. We found out in the project that the devices installed on the PCBs could be detached from the boards in non-distractive form by novel mechanical and electrical crushing and that the following "Devices Separation" was considerably a good method to concentrate minor rare metals. We also clarified the applicability of all the SDA bearing metals to the "Devices Separation".
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