硫酸塩水溶液中のSm2(SO4)3およびNd2(SO4)3の溶解度
希土類磁石材料のリサイクリングに関する基礎的研究
1989 年 105 巻 12 号 p. 965-970
詳細
1989 年 105 巻 12 号 p. 965-970
A new process consisting of fractional crystallization and electrowinning from sulfate solution was proposed for the recycling of rare earth magnet scraps which contain about 30% of Sm or Nd and 50-60% of Co or Fe. Fundamental data for the recycling, the solubilities of Sm2 (SO4) 3 in H2SO4-H2O and CoSO4-H2O as well as the solubilities of Nd2 (SO4) 3 in H2SO4-H2O and FeSO4-H2O were determined in the temperature range 0 to 80°C. The results are summarized as follows: 1) In increasing the temperature, the CoSO4 and FeSO4 solubilities in water increase, while Sm2 (SO4) 3 and Nd2 (SO4) 3 solubilities decrease sharply. 2) 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 within 0-80°C and Nd2 (SO4) 3· 5H2O at 80°C respectively. 3) In increasing the SO42- (H2SO4, CoS04, FeSO4), the solubility-[S042-] curves of Sm2 (SO4) 3and Nd2 (SO4) 3 show the maximum value which shifts to higher SO42-concentration with temperature increasing. It was presumed results essentially from the formation of RE (SO4) +and RE (SO4) 2-complexes. 4) It seems possible to recover Sm Nd and Co from rare earth magnet scraps with sulfate fractional crystallization method by controling temperature and SO42-concentration.
