Solubility of Sm2(SO4)3 and Nd2(SO4)3 in sulfate solutions

Yuezhou Wei, Nobuaki Sato, Michio Nanjo

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11 Citations (Scopus)


A new process consisting of fractional crystallization and electrowinning from sulfate solution is proposed for recycling rare earth magnet scrap which contains about 30% Sm or Nd and 50-60% Co or Fe. With increasing temperature, the CoSO4 and FeSO4 solubilities in water increase, while Sm2 (SO4)3 and Nd2(SO4)3 solubilities decrease sharply. From the results of X-ray diffraction and thermal analysis, the forms of equilibrating solid phases were identified as Sm2(SO4)3 · 8H2O from 0 to 80°C, Nd2(SO4)3 · 8H2O with 0-80°C and Nd2(SO4)3 · 5H2O at 80°C, respectively. In increasing the SO42-(H2SO4, CoSO4, FeSO4), the solubility - [SO42-] curves of Sm2(SO4)3 and Nd2(SO4)3 show the maximum value which shifts to higher SO42-concentration with temperature.

Original languageEnglish
Pages (from-to)965-970
Number of pages6
JournalShigen to sozai
Issue number12
Publication statusPublished - 1989 Nov 1

ASJC Scopus subject areas

  • Engineering(all)


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