US3629079A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alumina feed control
Assignee: Kaiser Aluminum and Chemical Corp
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Filing: 1968-02-23
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Granted: 1971-12-21
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Expires: 1988-02-23
Abstract
Abstract A method of controlling the feeding of alumina to a reduction cell and apparatus therefor. The method comprises the steps of producing a gradient variation in the supply current fed to the cells and obtaining at least one measurement of the voltage and the current across the cell for a first value of the current gradient and obtaining at least a second measurement of the voltage and current across the cell for a different value of the current gradient. An indication of the alumina concentration is derived from the first and second current and voltage current measurements. An amount of alumina which is related to the determined value of alumina concentration and which will restore the desired operating alumina concentration is then added to the cell.
Inventors
- 👤 Donald R Bristol
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:45
CPC Classifications
C; C25; C25C; C25C3/00; C25C3/06; C25C3/20
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
24 words
The method of claim 1 wherein different cells are selected for reduced feeding of alumina to induce an anode effect in successive program periods.
Claim 2
Dependent Claim
22 words
The method of claim 1 wherein the alumina concentration in the cells is maintained between about 2 and 4 percent by weight.
Claim 3
Dependent Claim
268 words
In the production of the aluminum by electrolytic reduction wherein an electrical current is supplied to a plurality of reduction cells connected in electrical series, a system for maintaining the alumina concentration in the reduction cells within predetermined limits comprising: a. means for feeding alumina to each of the cells; b. voltage measuring means connected across each of the cells; c. current measuring means connected across the current flow to the cells; d. a digital computer means programmed to i. select a particular cell to receive a reduced feeding of alumina to induce to induce an anode effect. ii. reduce the feeding of alumina to said selected cell to induce an anode effect whereby current to said cells is changed, iii. calculate the back EMF of each cell from the values of voltage and current prior to and during said anode effect by solving the simultaneous equations V1 A+ AI1 V2 A+ BI2 for A where A is the back EMF, V1 and I1 are the cell voltage and line current, respectively, prior to the anode effect and V2 and I2 are the cell voltage and line current, respectively, during the anode effect, iv. determine the alumina concentration in each of the cells by comparing the back EMF value with a predetermined tabulation of the relationship between back EMF and alumina concentration, v. generate a signal for each cell which is utilized to adjust the feeding rate of alumina to each of the cells so as to maintain the alumina concentration therein within a predetermined range; e. means responsive to said signals, to control the alumina feeding means.
Claim 4
Dependent Claim
39 words
The system of claim 4 wherein said digital computing means is programed to select different cells for reduced feeding rates during successive program intervals so that the induced anode effects are distributed among the cells electrically connected in series.
Claim 5
Dependent Claim
30 words
The system of claim 4 wherein the digital computing means is programmed to maintain the alumina concentration in each of the cells between about 2 and 4 percent by weight.
References Cited (Backward Citations)
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Cited
US3434945A
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US3455795A
Cited
US3380897A
Cited
US3471390A
Cited
US3400062A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |