Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Rare earth metal
Patent
1993-05-17
1994-11-08
Straub, Gary P.
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Rare earth metal
423263, C01F 1700
Patent
active
053624599
ABSTRACT:
The present invention is a method of recovering neodymium (Nd) from waste by-products of rare earth magnet manufacture. Two main waste by-products, NdFeB swarf and NdFeB slag, are treated by two respective chemical schemes as described above. However, the only major consumption of chemical compound in both schemes is hydrofluoric acid (HF). The present invention scheme for NdFeB swarf recovery is characterized by using acetic acid (HC.sub.2 H.sub.3 O.sub.2) having a pK value of approximately 4.7. The present invention scheme for NdFeB slag recovery is characterized by using sulfamic acid electrolyte bath having a pH value of approximately 2.7. The moist neodymium trifluoride (NdF.sub.3) produced by both schemes can be dried by using the same microwave radiation technique to produce dry neodymium trifluoride (NdF.sub.3) which contains less than 3% moisture.
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patent: 4906290 (1990-03-01), Worner
Morrison, J. W. et al., "Recovery of Metal Values from NdFeB Magnet Scrap," Bureau of Mines, pp. 1-17, no date.
Bos Steven
Chen Tony D.
Pure-Etch Co.
Rozsa Thomas I.
Straub Gary P.
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