Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Rare earth metal
Patent
1982-12-01
1983-08-23
Carter, Herbert T.
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Rare earth metal
423111, 423122, 423127, 423132, C01F 1700, C01G 1500
Patent
active
044003609
ABSTRACT:
A process is described whereby the by-products derived from the fabrication of Gd.sub.3 Ga.sub.5 O.sub.12 (GGG) wafers sliced from boules grown from Gd.sub.2 O.sub.3 and Ga.sub.2 O.sub.3 can be reprocessed in sufficient purity to be re-used in the process of growing GGG boules, thereby improving the economics of GGG wafer production. Gadolinium and gallium oxides are recovered and separated from transition metal impurities introduced during fabrication of GGG wafers. The "saw kerf" produced from slicing the crystal boule is dissolved in HCl and filtered to remove residual solids. Gasolinium oxalate is precipitated from the acidic solution by the addition of oxalic acid. Calcination at 850.degree. C. resulted in the isolation of Gd.sub.2 O.sub.3 of >99.99 purity.
The pH of the filtrate is adjusted to about 11 with alkali metal hydroxide followed by the addition of sulfide ion. The precipitated transition metal sulfides are removed by filtration. Excess sulfide is removed by treatment with 30% H.sub.2 O.sub.2. The pH is adjusted to 8.5 and the gallium hydroxide, which precipitated, removed by filtration. Calcination at about 850.degree. C. resulted in the recovery of Ga.sub.2 O.sub.3 in yields of the order of 95% and of 99.99% purity.
REFERENCES:
patent: 3506585 (1970-04-01), Otsuka et al.
patent: 4198231 (1980-04-01), Gusset
patent: 4375453 (1983-03-01), Nalewajek et al.
Schultze et al, "Chemical Absts.", vol. 85, 1976, #66231n.
Allied Corporation
Carter Herbert T.
Friedenson Jay P.
Plantamura Arthur J.
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