US4041137A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing aluminum fluoride
Assignee: Sumitomo Aluminum Smelting Co
•
Filing: 1976-03-25
•
Granted: 1977-08-09
•
Expires: 1996-03-25
Abstract
Abstract In the production of aluminum fluoride, a fluorine compound is absorbed from a gas containing the fluorine compound into a gas absorbing liquor comprising water containing alumina or hydrated alumina, or an aqueous aluminum fluoride solution containing alumina or hydrated alumina, and the absorbed fluorine compound is reacted with alumina or hydrated alumina to precipitate hydrated aluminum fluoride of high quality.
Inventors
- 👤 Tatsuo Abe
- 👤 Toshiki Okamoto
- 👤 Takao Sakakura
- 👤 Tatsuo Tateno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:09
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/48; C01F7/50
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
118 words
A method for the production of aluminum fluoride from a gas containing a fluorine compound, which method comprises circulating between a gas absorbing zone and a storage zone a gas absorbing liquor comprising either water containing alumina or hydrated alumina, or an aqueous aluminum fluoride solution containing alumina or hydrated alumina, introducing said gas into said gas absorbing zone and absorbing said gas into said gas absorbing liquor whereby the absorbed fluorine compound is reacted with alumina or hydrated alumina to precipitate the fluorine as hydrated aluminum fluoride, filtering said precipitated hydrated aluminum fluoride from said gas absorbing liquor and recycling the filtrate from the filtration to the storage zone and recycling same therefrom into the absorbing zone.
Claim 2
Independent Claim
118 words
A method for the production of aluminum fluoride from a gas containing a fluorine compound, which method comprises circulating between a gas absorbing zone and a storage zone a gas absorbing liquor comprising either water containing alumina or hydrated alumina, or an aqueous aluminum fluoride solution containing alumina or hydrated alumina, introducing said gas into said gas absorbing zone and absorbing said gas into said gas absorbing liquor whereby the absorbed fluorine compound is reacted with alumina or hydrated alumina to precipitate the fluorine as hydrated aluminum fluoride, filtering said precipitated hydrated aluminum fluoride from said gas absorbing liquor and recycling the filtrate from the filtration to the storage zone and recycling same therefrom into the absorbing zone.
Claim 3
Dependent Claim
21 words
A method according to claim 1, wherein said gas has a fluorine concentration of less than about 10 g/Nm 3 .
Claim 4
Dependent Claim
21 words
A method according to claim 1, wherein said gas has a fluorine concentration of less than about 2 g/Nm 3 .
Claim 5
Dependent Claim
18 words
A method according to claim 1, wherein said gas is an off gas from an aluminum electrolytic cell.
Claim 6
Dependent Claim
33 words
A method according to claim 1, wherein the amount of added alumina or hydrated alumina is 1 to 2 times that theoretically required based on the fluorine absorbed by said gas absorbing liquor.
Claim 7
Dependent Claim
18 words
A method according to claim 1, wherein said filtered aluminum fluoride hydrate is calcined into anhydrous aluminum fluoride.
Claim 8
Independent Claim
144 words
A method for the production of aluminum fluoride from a gas containing a fluorine compound, which method comprises circulating between a gas absorbing zone and a storage zone a gas absorbing liquor comprising water containing alumina or hydrated alumina, an aqueous aluminum fluoride solution, or an aqueous aluminum floride solution containing alumina or hydrated alumina, introducing said gas into said gas absorbing zone and absorbing said gas into said absorbing liquor, introducing said gas absorbing liquor containing said gas into a reaction zone, adding alumina or hydrated alumina to the gas absorbing liquor in said reaction zone whereby said absorbed fluorine compound is reacted with said alumina or hydrated alumina to precipitate hydrated aluminum fluoride, filtering said hydrated aluminum fluoride from said gas absorbing liquor, and recycling the filtrate from the filtration to the storage zone and recycling same therefrom into the absorbing zone.
Claim 9
Independent Claim
144 words
A method for the production of aluminum fluoride from a gas containing a fluorine compound, which method comprises circulating between a gas absorbing zone and a storage zone a gas absorbing liquor comprising water containing alumina or hydrated alumina, an aqueous aluminum fluoride solution, or an aqueous aluminum floride solution containing alumina or hydrated alumina, introducing said gas into said gas absorbing zone and absorbing said gas into said absorbing liquor, introducing said gas absorbing liquor containing said gas into a reaction zone, adding alumina or hydrated alumina to the gas absorbing liquor in said reaction zone whereby said absorbed fluorine compound is reacted with said alumina or hydrated alumina to precipitate hydrated aluminum fluoride, filtering said hydrated aluminum fluoride from said gas absorbing liquor, and recycling the filtrate from the filtration to the storage zone and recycling same therefrom into the absorbing zone.
Claim 10
Dependent Claim
18 words
A method according to claim 7, wherein said filtered aluminum fluoride hydrate is calcined into anhydrous aluminum fluoride.
Claim 11
Dependent Claim
21 words
A method according to claim 7, wherein said gas has a fluorine concentration of less than about 10 g/Nm 3 .
Claim 12
Dependent Claim
21 words
A method according to claim 7, wherein said gas has a fluorine concentration of less than about 2 g/Nm 3 .
Claim 13
Dependent Claim
18 words
A method according to claim 7, wherein said gas is an off gas from an aluminum electrolytic cell.
Claim 14
Dependent Claim
47 words
A method according to claim 7, wherein said gas absorbing liquor is either water or an aqueous aluminum fluoride solution to which alumina or hydrated alumina is added in an amount of 20 to 80% of that theoretically required based on the fluorine absorbed by said liquor.
Claim 15
Dependent Claim
32 words
A method according to claim 7, wherein the total amount of said alumina or hydrated alumina is 1 to 2 times that theoretically required based on the fluorine absorbed by said liquor.
Claim 16
Dependent Claim
26 words
A method according to claim 7, wherein said gas absorbing liquor is an aqueous aluminum fluoride solution which is a filtrate recycled from the filtration process.
Claim 17
Dependent Claim
19 words
A method according to claim 1, wherein the pH of said gas absorbing liquor is less than about 6.
Claim 18
Dependent Claim
19 words
A method according to claim 7, wherein the pH of said gas absorbing liquor is less than about 6.
Claim 19
Dependent Claim
26 words
A method according to claim 1, wherein the concentration of alumina or hydrated alumina in said gas absorbing liquor is lower than about 10% by weight.
Claim 20
Dependent Claim
26 words
A method according to claim 7, wherein the concentration of alumina or hydrated alumina in said gas absorbing liquor is lower than about 10% by weight.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |