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.
|Number of pages||6|
|Journal||Shigen to sozai|
|Publication status||Published - 1989 Nov 1|
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