In:
journal of Korean Powder Metallurgy Institute, The Korean Powder Metallurgy & Materials Institute, Vol. 25, No. 3 ( 1970-01-01), p. 213-219
Abstract:
〈 p 〉 We report a method for preparing rare earth oxides (Re 〈 sub 〉 x 〈 /sub 〉 O 〈 sub 〉 y 〈 /sub 〉 ) from the recycling process for spent Ni-metal hydride (Ni-MH) batteries. This process first involves a leaching of spent Ni-MH powders with sulfuric acid at 90°C, resulting in rare earth precipitates (i.e., NaRE(SO 〈 sub 〉 4 〈 /sub 〉 ) 〈 sub 〉 2 〈 /sub 〉 ·H 〈 sub 〉 2 〈 /sub 〉 O, RE = La, Ce, Nd), which are converted into rare earth oxides via two different approaches: i) simple heat treatment in air, and ii) metathesis reaction with NaOH at 70°C. Not only the morphological features but also the crystallographic structures of all products are systematically investigated using field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD); their thermal behaviors are also analyzed. In particular, XRD results show that some of the rare earth precipitates are converted into oxide form (such as La 〈 sub 〉 2 〈 /sub 〉 O 〈 sub 〉 3 〈 /sub 〉 , Ce 〈 sub 〉 2 〈 /sub 〉 O 〈 sub 〉 3 〈 /sub 〉 , and Nd 〈 sub 〉 2 〈 /sub 〉 O 〈 sub 〉 3 〈 /sub 〉 ) with heat treatment at 1200°C; however, secondary peaks are also observed. On the other hand, rare earth oxides, Re 〈 sub 〉 x 〈 /sub 〉 O 〈 sub 〉 y 〈 /sub 〉 can be successfully obtained after metathesis of rare earth precipitates, followed by heat treatment at 1000°C in air, along with a change of crystallographic structures, i.e., NaRE(SO 〈 sub 〉 4 〈 /sub 〉 ) 〈 sub 〉 2 〈 /sub 〉 ·H 〈 sub 〉 2 〈 /sub 〉 O → RE(OH) 〈 sub 〉 3 〈 /sub 〉 →Re 〈 sub 〉 x 〈 /sub 〉 O 〈 sub 〉 y 〈 /sub 〉 . 〈 /p 〉
Type of Medium:
Online Resource
ISSN:
2799-8525
,
2799-8681
DOI:
10.4150/KPMI.2018.25.3.213
Language:
English
Publisher:
The Korean Powder Metallurgy & Materials Institute
Publication Date:
1970
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