Patent US3839167A successfully refreshed from Google Patents.
US3839167A
Expired / Lapsed
US
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Novel alumina feed for aluminum cell
Assignee: Alcoa Corp
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Filing: 1973-06-28
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Granted: 1974-10-01
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Expires: 1993-06-28
Abstract
Abstract Use of an alumina which has a total water of 3 to 20 wt.-percent and a surface area of at least 45 m2/g as cell feed improves the efficiency of operation of an electrolytic cell for reduction of alumina to aluminum.
Inventors
- 👤 W Sleppy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:08
CPC Classifications
C; C25; C25C; C25C3/00; C25C3/06; C25C3/18
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
75 words
A PROCESS FOR INCREASING THE EFFECIENCY OF SMELTING ALUMINUM, COMPRISING ADDING, SYBSTANTIALLY CONTINUOUSLY, DIRECTLY TO A MOLTEN ELECTROLYTE IN A CELL FOR THE ELECTROLYTIC REDUCTION OF ALUMINA TO ALUMINUM, AN ALUMINA WHICH HAS A TOTAL WATER OF FROM 3 TO 20 WEIGHT PERCENT AND A SURFACE AREA OF AT LEAST 45 M2/G, SAID ALUMINA COMPRISING UP TO 100 PERCENT OF THE AL2O3 FED TO SAID CELL, AND ELECTROLYTICALLY REDUCING ALUMINA TO ALUMINUM IN SAID CELL.
Claim 2
Dependent Claim
75 words
A PROCESS FOR INCREASING THE EFFECIENCY OF SMELTING ALUMINUM, COMPRISING ADDING, SYBSTANTIALLY CONTINUOUSLY, DIRECTLY TO A MOLTEN ELECTROLYTE IN A CELL FOR THE ELECTROLYTIC REDUCTION OF ALUMINA TO ALUMINUM, AN ALUMINA WHICH HAS A TOTAL WATER OF FROM 3 TO 20 WEIGHT PERCENT AND A SURFACE AREA OF AT LEAST 45 M2/G, SAID ALUMINA COMPRISING UP TO 100 PERCENT OF THE AL2O3 FED TO SAID CELL, AND ELECTROLYTICALLY REDUCING ALUMINA TO ALUMINUM IN SAID CELL.
Claim 3
Dependent Claim
30 words
The process of claim 1 wherein said alumina is added in increments at intervals of up to ten minutes in amounts calculated to maintain constant alumina concentration in the electrolyte.
Claim 4
Dependent Claim
39 words
The process of claim 1 wherein said electrolyte consists essentially of NaF, AlF3, and Al2O3 and has an NaF to AlF3 weight ratio up to 1.1:1 and wherein said alumina has a total water of 8 to 20 percent.
Claim 5
Dependent Claim
19 words
The process of claim 3 wherein said alumina has a total water in the range 10 to 18 percent.
Claim 6
Dependent Claim
19 words
The process of claim 3 wherein said alumina has a surface area in the range 135 to 180 m2/g.
Claim 7
Dependent Claim
26 words
The process of claim 1 wherein said alumina amounts to at least 50 percent by weight of the total amount of Al2O3 fed to the cell.
Claim 8
Dependent Claim
21 words
The process of claim 1 wherein said alumina amounts to at least 90 percent of the Al2O3 fed to the cell.
Claim 9
Dependent Claim
51 words
A process for increasing the efficiency of smelting aluminum, comprising adding, substantially continuously, directly to a molten electrolyte in a ceLl for the electrolytic reduction of alumina to aluminum, alumina having a water content effective for dispersing its individual particles upon addition thereof to said electrolyte but insufficient to cause mucking.
Claim 10
Dependent Claim
51 words
A process for increasing the efficiency of smelting aluminum, comprising adding, substantially continuously, directly to a molten electrolyte in a ceLl for the electrolytic reduction of alumina to aluminum, alumina having a water content effective for dispersing its individual particles upon addition thereof to said electrolyte but insufficient to cause mucking.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |