New preparation and recycling procedure to recover rare earth elements from magnets by using a closed loop treatment

Abstract

The use of critical raw materials also increases due to the higher demand on electrical and electronic equipment (EEE). The high content of valuable substances in EEE in relation to primary ores secures a potential for its use as new raw materials sources, the so-called ‘urban mining’. Positive effects of urban mining are to save existing mineral resources as well as to relieve the primary production and get a new opportunity instead of landfilling. The subsequently described research work at the Chair of Nonferrous Metallurgy at the University of Leoben is concentrated on the preparation of hard disc drives (HDDs). Currently, the main problem to recover neodymium–iron–boron (NIB) magnets is the missing technology for preparation. A disassembling of HDD by hand is not economic and a treatment by a shredding machine destroys the NIB magnets, so that they cannot be separated and fed into a proper recycling process. Therefore, the investigation leads to a thermal treatment to obtain the components of a HDD in separated form. The investigation also focuses on a metallurgical way to recover the technological metals like neodymium, copper, gold as well as a reusable aluminium alloy. Therefore, a closed loop treatment was found to clean the leaching agent and reuse it to reduce the amount of waste streams.