Recovery of samarium and neodymium from rare earth magnet scraps by fractional crystallization method: Fundamental study on the recycling of rare earth magnet(II)

Nobuaki Sato, Yuezhou Wei, Michio Nanjo, Masanori Tokuda

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)1-13
Number of pages13
JournalMetallurgical Review of MMIJ (Mining and Metallurgical Institute of Japan)
Volume15
Issue number1
Publication statusPublished - 1998 Jul 1

ASJC Scopus subject areas

  • Metals and Alloys

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