Recovery of Sm and Nd from rare earth magnet scraps which contain ∼ 30% of Sm or Nd and 50∼60% of Co or Fe was examined by fractional crystallization of their sulfates. The results are summarized as follows: 1) When H 2SO 4 was added into HNO 3 solution containing Sm and Co, solubility of Sm decreased and Sm sulfate hydrate, Sm 2(SO 4) 3 · 8H 2O preferentially precipitated. 2) Samarium sulfate hydrate of 96.5% purity with recovery rate 87.1% was obtained from SmCo 5 magnet scraps by the fractional crystallization. Effective results were also obtained when Sm 2(Co,Fe,Cu,Zr) 17 was examined similarly. 3) Solubility of Nd 2(SO 4) 3 in H 2SO 4 solution largely decreased by addition of small amount of ethanol, while those of FeSO 4 and Fe 2(SO 4) 3 slightly decreased. 4) Addition of ethanol was proved to be effective for recovery of Nd from H 2SO 4-HNO 3 solution containing Nd and Fe by fractional crystallization. 5) Neodymium sulfate hydrate, Nd 2(SO 4) 3·8H 2O, 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 H 2SO 4.
|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