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US 4,034,068 AGranted
Process for preparation of ammonium tetrafluoroaluminate
AssigneeCentral Glass Company, Limited
InventorsMinoru Aramaki, Etsuo Ushirogouchi
Life of this patent
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Abstract
An inorganic acid typified by H.sub.2 SO.sub.4 is added to an aqueous slurry of (NH.sub.4).sub.3 AlF.sub.6 and either Al(OH).sub.3 or Al.sub.2 O.sub.3, and the resulting mixture is kept for a while under the atmospheric pressure at or somewhat above room temperature. The acid is added preferably in such an amount that the pH of the slurry after completion of the reaction is 4 to 7.
Claims10
A process for the preparation of ammonium tetrafluoroaluminate comprising the steps of:
- (a) preparing an aqueous slurry of ammonium hexafluoroaluminate and an aluminum compound selected from the group consisting of aluminum hydroxide and aluminum oxide, the molar ratio of said ammonium hexafluoroaluminate to said aluminum compound being about 1:1/2;
- (b) adding an inorganic acid selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid to said slurry in such an amount that the molar ratio of said ammonium hexafluoroaluminate to said inorganic acid in the resulting mixture is about 4:3 for sulfuric acid, and about 2:3 for hydrochloric acid and nitric acid, leaving an excess amount of the acid necessary to neutralize free ammonia which may be present in said slurry;
- the resultant reaction system being kept at a temperature between room temperature and about 100.degree. C. at atmospheric pressure;
- and
- (c) recovering the ammonium tetrafluoroaluminate product from the reaction system in crystalline form by filtration.
2 more elements
A process for the preparation of ammonium tetrafluoroaluminate comprising the steps of:
- (a) preparing an aqueous slurry of ammonium hexafluoroaluminate and an aluminum compound selected from the group consisting of aluminum hydroxide and aluminum oxide, the molar ratio of said ammonium hexafluoroaluminate to said aluminum compound being about 1:1/2;
- (b) adding an inorganic acid selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid to said slurry in such an amount that the molar ratio of said ammonium hexafluoroaluminate to said inorganic acid in the resulting mixture is about 4:3.5 for sulfuric acid, and about 2:3.5 for hydrochloric acid and nitric acid, and that the pH of the liquid component of the resultant reaction system is within the range of 4.0 to 7.0 after formation of ammonium tetrafluoroaluminate, the resultant reaction system being kept at a temperature between room temperature and about 100.degree. C. at atmospheric pressure;
- and
- (c) recovering the ammonium tetrafluoroaluminate product from the reaction system in crystalline form by filtration.
1 more element
Dependencies are inferred from the claim text.