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Hitachi

Corporate InformationResearch & Development

April 1, 2014

Report from Presenter

The Minerals Metals and Materials Society 143rd Annual Meeting & Exhibition (TMS2014) was held in San Diego, USA from February 16 to 20. This meeting covered various field such as energy, resources recycling in addition to minerals, metals and materials. This year about 4000 people from 70 countries attended this meeting and made presentations.

Yokohama Research Laboratory made three presentations entitled "Environment-Friendly Recycling Process for Rare Earth Metals in End-of-Life Electric Products", "Recovery of Rare Earth Metals in Used Magnets by Molten Magnesium" and "Assessment of Environmental Impact of Rare Earth Metals Recycling from Used Magnets".

Rare earth magnet, containing rare earth metals such as neodymium (Nd) and dysprosium (Dy), is indispensable to enhance the performance of electric products utilizing motors. However, there is an instability in the procurement of rare earth metals due to the localization of their production. Recycling of the rare earths in used products is therefore becoming important.

Hitachi group has developed the products disassembly process and pyrometallurgical recovery process for rare earth metals, which are necessary to complete the recycling loop for rare earths (Fig. 1). We reported in the first paper that we examined each process using equipments which can process several-kg or several tens kg of magnets per day. In the pyrometallurgical recovery process, molten magnesium is used as an extraction medium (Fig. 2).


Fig.1 Approach of Hitachi group
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Fig.2 Pyrometallurgical recovery process of rare
earth metals

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In the second paper, we reported the effect of process conditions and the approach to improve the yield of Dy, which is more expensive than Nd. Since this recovery process emits much less waste than the conventional process, the lower environmental impact is expected. We evaluated the environmental impact of the process by Life-cycle Impact assessment Method based on Endpoint modeling ver.2 (LIME2) developed by The National Institute of Advanced Industrial Science and Technology (AIST) and reported in the third paper. It was clarified that environmental impact of electricity for Mg heating was very large and the reduction of Mg for extraction was required.

We clarified that the electricity for Mg heating had a large impact so that the reduction of the amount of Mg used for extraction would benefit in the further reduction of its environmental impact.

This research was part of the project "The development of technology for recycling rare earth metals from urban mines" supported by the Ministry of Economy, Trade and Industry, "Development of Technology for Removal of Magnets from Products Containing Rare earth Magnets and Recovery of Rare Earths" and "Development of Technology for Recycling High-performance Rare Earth Magnets from Used Motors" supported by the New Energy and Industrial Technology Development Organization. Design of pyrometallurgical recycling equipment was assisted by Toho Titanium Co. Ltd.

(By AKAHORI Tomohiko and SAEKI Tomonori)

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