Recycling of Rare Earths and Iron from NdFeB Magnet Scrap

Abstract

The U.S. Department of the Interior Bureau of Mines, Investigated methods to recover valuable rare-earth materials from NdFeB magnet scrap. Although several processing techniques were evaluated, the best separation of rare-earths from the NdFeB magnet scrap was obtained by sulfuric acid dissolution followed by precipitation of recyclable rare-earth salts. Both sodium and ammonium intermediate double salt precipitates that can be converted to a variety of useful neodymium products were investigated. The sodium system showed a neodymium recovery of 98 pet while the ammonium system yielded 70 pet during double salt precipitation. The iron-rich effluent following the rare-earth recovery was treated to produce sodium and ammonium iron Jarosites that can be disposed of or converted to hematite. By following this new procedure, many materials handling and economic disadvantages found with fluoride or oxalate direct precipitation were avoided. © 1993, Walter de Gruyter. Alle Rechte vorbehalten.