Recovery of Sm and Nd from rare earth magnet scraps which contain approximately 30% of Sm or Nd and 50 to approximately 60% of Co or Fe was examined by fractional crystallization of their sulfates. The results are summarized as follows: 1) When H2SO4 was added into HNO3 solution containing Sm and Co, solubility of Sm decreased and Sm sulfate hydrate, Sm2(SO4)3·8H2O preferentially precipitated. 2) Samarium sulfate hydrate of 96.5% purity with recovery rate 87.1% was obtained from SmCo5 magnet scraps by the fractional crystallization. Effective results were also obtained when Sm2(Co,Fe,Cu,Zr)17 was examined similarly. 3) Solubility of Nd2(SO4)3 in H2SO4 solution largely decreased by addition of small amount of ethanol, while those of FeSO4 and Fe2(SO4)3 slightly decreased. 4) Addition of ethanol was proved to be effective for recovery of Nd from H2SO4-HNO3 solution containing Nd and Fe by fractional crystallization. 5) Neodymium sulfate hydrate, Nd2(SO4)3·8H2O, of 96.8% purity with recovery rate 97.1% was obtained from Nd-Fe-B magnet scraps by fractional crystallization with addition of ethanol as well as H2SO4.
|Number of pages||13|
|Journal||Metallurgical Review of MMIJ (Mining and Metallurgical Institute of Japan)|
|Publication status||Published - 1998 Jul 1|
ASJC Scopus subject areas
- Metals and Alloys