Recent Trend on the Studies of Recycling Technologies of Rare Earth Metals

There is uncertainty in the supply of rare earth resources. Technical developments on the resource saving of rare earths and the alternate materials are important challenges, and the development of recycling technologies is also important for securing stable supply of rare earth resources. The waste of neodymium magnet that is the industrially-important product containing rare earth metals is currently recycled by a hydrometallurgical method. However, the hydrometallurgical method generates a large volume of waste solution and consumes a large amount of energy. In order to develop an environmentally-sound recycling process, various studies on pyrometallurgical methods have been conducted. One of the authors developed the molten metal extraction method and the flux remelting method. The pyrometallurgical methods are anticipated as the recycling processes with small waste generation and low energy consumption. Research and development on environmentally-sound recycling technologies for rare earths has to be advanced from environmental aspects as well as economic aspects.