US3736244A - Electrolytic cells for the production of aluminum - Google Patents
Electrolytic cells for the production of aluminum Download PDFInfo
- Publication number
- US3736244A US3736244A US00139154A US3736244DA US3736244A US 3736244 A US3736244 A US 3736244A US 00139154 A US00139154 A US 00139154A US 3736244D A US3736244D A US 3736244DA US 3736244 A US3736244 A US 3736244A
- Authority
- US
- United States
- Prior art keywords
- bars
- cell
- aluminum
- cathode
- lining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title abstract description 9
- 229910052782 aluminium Inorganic materials 0.000 title abstract description 9
- 238000004519 manufacturing process Methods 0.000 title description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 18
- 229910052799 carbon Inorganic materials 0.000 abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 12
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 abstract description 6
- 229910052742 iron Inorganic materials 0.000 abstract description 6
- 238000011084 recovery Methods 0.000 abstract description 4
- 239000003792 electrolyte Substances 0.000 abstract description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/16—Electric current supply devices, e.g. bus bars
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
Definitions
- FIG. 2 ELECTROLYTIC CELLS FOR THE PRODUCTION OF ALUMINUM Filed April 30, 1971 FIG. 2
- An electrolytic cell for the recovery of aluminum comprising a pot for the fluoride electrolyte with a carbon bottom and iron cathode bars extending through the carbon bottom to emerge from each side of the cell in which the cross section of the bars on each side of the central length which lies beneath the anodes is less than that of the central length of the bars.
- This invention relates to electrolytic cells for the recovery of aluminum from an alumina-containing fluoride melt.
- a typical cell is shown diagrammatically in FIG. 1 of the accompanying drawings, and comprises a steel pot 12 lined by an insulating layer 13 of heat-resistant material. Within this lining there is a lining 11 of carbon in which iron cathode bars 17 are embedded. The cathodically separated aluminum collects as shown at 14 below the fluoride melt shown at 10 and on the surface 15 of the carbon lining 11. A crust 22 forms on the fluoride melt as a result of solidification, and is covered by a layer 23 of aluminum oxide.
- Anodes 18 of amorphous carbon dip into the melt from above, and normally are carried by rods 19 which, as shown at 20, are fixed to current conducting beams 21. These beams can be raised or lowered through hoisting units 25 mounted on columns 26.
- the distance d from the underside of an anode to the surface 116 of the aluminum which is known as the interpolar distance, can be varied by vertical movement of the beam 21.
- the temperature of the melt is kept constant as far as possible between 940 and 975 C.
- Oxygen is released at the anodes and combines with the carbon of the anodes to form carbon monoxide and carbon dioxide. Because of this, the lower ends of the anodes are consumed to an extent of about 1.5 to 2 cm. of their length each day in accordance with the particular construction of the cell.
- the cathode bars 17 are good heat conductors, and accordingly carry away heat outwards from within the cell. The heat thus lost must be made up by the supply of electrical energy. In addition, heat (PR) is generated in the bars, but by decreasing the thermal gradient reduces the amount of heat which would otherwise flow outwards by conduction.
- FIG. 2'of the accompanying drawings is a diagrammatic cross-section through the cell. It shows that the cathode bars 17 extend completely through the carbon lining 11 to emerge from each side of the cell, and lie beneath the anodes. In the cell shown there are tworows of anodes 18, each carried by its own beam 21.
- the cathode bars 17 have two functions. One is to collect current from that part of the carbon lining which lies beneath the anodes, and which may be called the active part of the lining, and which is shown at 27. The other function is to carry the current outwards from the cell, so that the lengths 28 of the bars outside the "United States Patent ice active part act simply as current conductors. In the central length 29 between the two lengths 28, the current density in each cathode bar increases outwards from the centre. This central length 29 within the active part of the carbon lining must be of large cross-section so as to present a considerable area of contact resistance.
- the bars are of uniform cross-section throughout their whole length, but in view of the conduction of heat outwards from the cell this is not satisfactory.
- the cross-section of the bars outside the active part of the carbon lining that is to say on each side of the central length 29 which lies beneath the anodes, is less than that of this central length. This difference in cross-section is clearly shown in FIG. 2.
- R W40 (percent)
- R Ratio of the cathode bar cross-section outside the active part of the carbon lining to the cathode bar cross-section inside the active part (percent).
- the ratio R is preferably in accordance with this equation i10%.
- the heat loss through the 19 bars is from 400.000 to 500.000 kcal. in 24 hours. If the cross-section of the lengths 28 is so reduced as to give a ratio R of 50%, 250,000 to 300,000 kcal. can be saved in 24 hours, which corresponds to a reduction in the specific consumption of electrical energy up to 0.5 kwh./kg. of Al. Additionally, by the reduction of the removal of heat by the cathode bars the thermal gradient in the bottom of the cell is reduced, and this has a satisfactory effect on the maintenance of the carbon lining of the pot. Moreover, the savings in the amount of iron required for the cathode bars can amount to one ton or more per cell.
- An electrolytic cell for the recovery of aluminum from an alumina-containing fluoride melt comprising a pot for the electrolyte with a carbon lining on the bottom and iron cathode bars extending through the carbon lining to emerge from each side of the cell, in which the crosssection of the bars on each side of the central length which lies beneath the anodes in the active part of the lining is less than that of the central length of the bars.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
AN ELECTROLYTIC CELL FOR THE RECOVERY OF ALUMINUM COMPRISING A POT FOR THE FLUORIDE ELECTROLYTE WITH A CARBON BOTTOM AND IRON CATHODE BARS EXTENDING THROUGH THE CARBON BOTTOM TO EMERGE FROM EACH SIDE OF THE CELL IN WHICH THE DROSS SCTION OF THE BARS ON EACH SIDE OF THE CENTRAL LENGTH WHICH LIES BENEATH THE ANODES IS LESS THAN THAT OF THE CENTRAL LENGTH OF THE BARS.
Description
May 29, 1973 BQHNER ETAL 3,736,244
ELECTROLYTIC CELLS FOR THE PRODUCTION OF ALUMINUM Filed April 30, 1971 FIG. 2
mull".
INVENTORS HAN S BOH NER WOLFGANG SCHMIDT-HATTING ATTORNEYS 3,736,244 ELECTROLYTIC CELLS FOR THE PRODUCTION OF ALUMINUM Hans Bohner, Fehraltorf, and Wolfgang Schmidt-Batting, Chippis, Switzerland, assignors to Swiss Allllllllllllm Ltd., Chippis, Switzerland Filed Apr. 30, 1971, Ser. No. 139,154 Claims priority, application Switzerland, May 1, 1970, 6,582/70 Int. Cl. C22d 3/02; B01k 3/04 US. Cl. 204--243 R 2 Claims ABSTRACT OF THE DISCLOSURE An electrolytic cell for the recovery of aluminum comprising a pot for the fluoride electrolyte with a carbon bottom and iron cathode bars extending through the carbon bottom to emerge from each side of the cell in which the cross section of the bars on each side of the central length which lies beneath the anodes is less than that of the central length of the bars.
This invention relates to electrolytic cells for the recovery of aluminum from an alumina-containing fluoride melt.
A typical cell is shown diagrammatically in FIG. 1 of the accompanying drawings, and comprises a steel pot 12 lined by an insulating layer 13 of heat-resistant material. Within this lining there is a lining 11 of carbon in which iron cathode bars 17 are embedded. The cathodically separated aluminum collects as shown at 14 below the fluoride melt shown at 10 and on the surface 15 of the carbon lining 11. A crust 22 forms on the fluoride melt as a result of solidification, and is covered by a layer 23 of aluminum oxide.
The distance d from the underside of an anode to the surface 116 of the aluminum, which is known as the interpolar distance, can be varied by vertical movement of the beam 21.
In the operation of such a typical cell the temperature of the melt is kept constant as far as possible between 940 and 975 C. Oxygen is released at the anodes and combines with the carbon of the anodes to form carbon monoxide and carbon dioxide. Because of this, the lower ends of the anodes are consumed to an extent of about 1.5 to 2 cm. of their length each day in accordance with the particular construction of the cell.
The cathode bars 17 are good heat conductors, and accordingly carry away heat outwards from within the cell. The heat thus lost must be made up by the supply of electrical energy. In addition, heat (PR) is generated in the bars, but by decreasing the thermal gradient reduces the amount of heat which would otherwise flow outwards by conduction.
FIG. 2'of the accompanying drawings is a diagrammatic cross-section through the cell. It shows that the cathode bars 17 extend completely through the carbon lining 11 to emerge from each side of the cell, and lie beneath the anodes. In the cell shown there are tworows of anodes 18, each carried by its own beam 21.
Now the cathode bars 17 have two functions. One is to collect current from that part of the carbon lining which lies beneath the anodes, and which may be called the active part of the lining, and which is shown at 27. The other function is to carry the current outwards from the cell, so that the lengths 28 of the bars outside the "United States Patent ice active part act simply as current conductors. In the central length 29 between the two lengths 28, the current density in each cathode bar increases outwards from the centre. This central length 29 within the active part of the carbon lining must be of large cross-section so as to present a considerable area of contact resistance.
In practice, the bars are of uniform cross-section throughout their whole length, but in view of the conduction of heat outwards from the cell this is not satisfactory.
According to the invention the cross-section of the bars outside the active part of the carbon lining, that is to say on each side of the central length 29 which lies beneath the anodes, is less than that of this central length. This difference in cross-section is clearly shown in FIG. 2.
It is undesirable to reduce the cross-section of the lengths 28 too much, because reduction leads to increase in the PR heat because of the higher current density in each length. More of this heat could be produced than would be saved by reduction in the amount of heat lost by conduction. The point at which there is no saving in heat loss, and therefore of electrical energy, can best be determined by practical tests on a given cell. In deciding where the economic limit lies, account must also be taken of the saving in the material of the cathode bars.
Ignoring the saving in material, which is of a minor nature in comparison with the saving of energy, it is possible to determine the optimum reduction in cross-section of the cathode bars outside the active part of the carbon lining to the cross-section inside the active part) is given by the following equation:
R: W40 (percent) R. Ratio of the cathode bar cross-section outside the active part of the carbon lining to the cathode bar cross-section inside the active part (percent).
I. Current density in the cathode bars (A). 6. Specific electric resistance of the cathode bars at a temperature which corresponds to /2(T +T) (Qm L. Length of the cathode bars outside the active part of the carbon lining (m).
a. Proportion of the PR heat of the cathode bars which does not flow outwards.
A. Specific thermal conductivity of the cathode bars at a temperature which corresponds to kcal.
mh. C.
T Temperature of the cathode bars at the outlet point of the rods from the active part of the bottom lining C.).
T Temperature of the cathode bars at their outer ends A Cross-section of the cathode bars inside the active part of the carbon lining (m.
In the invention the ratio R is preferably in accordance with this equation i10%.
As an example, in a ka. cell with 19 iron cathode bars, that is to say with 38 bar ends projecting outwards, the various factors in the equation may be as follows:
X 45 kcaL/mh. C. T 700 C.
Calculation shows that the ratio would be 50%, and accordingly preferably should not be less than 45% or more than 55%.
In an electrolytic cell of the size in question witz bars of uniform cross-section throughout their length, the heat loss through the 19 bars is from 400.000 to 500.000 kcal. in 24 hours. If the cross-section of the lengths 28 is so reduced as to give a ratio R of 50%, 250,000 to 300,000 kcal. can be saved in 24 hours, which corresponds to a reduction in the specific consumption of electrical energy up to 0.5 kwh./kg. of Al. Additionally, by the reduction of the removal of heat by the cathode bars the thermal gradient in the bottom of the cell is reduced, and this has a satisfactory effect on the maintenance of the carbon lining of the pot. Moreover, the savings in the amount of iron required for the cathode bars can amount to one ton or more per cell.
What We claim is:
1. An electrolytic cell for the recovery of aluminum from an alumina-containing fluoride melt comprising a pot for the electrolyte with a carbon lining on the bottom and iron cathode bars extending through the carbon lining to emerge from each side of the cell, in which the crosssection of the bars on each side of the central length which lies beneath the anodes in the active part of the lining is less than that of the central length of the bars.
2. A process for operating an electrolytic cell according to claim 1 in which the ratio R of the cross-section of the lengths of the cathode bars outside the central lengths relative to the cross-section beneath the anodes has the value R+10% R where I being the current density in the cathode bars in Amperes, 6 the specific electric resistance of the cathode bars in nm. at a temperature which corresponds to /z(T '+T- L the length of the cathode bars outside the active part of the lining in meters, or the proportion of the Joules law effect of the cathode bars which does not flow outwards, A the specific thermal conductivity in kcaL/mh. C. of the cathode bars at a temperature which corresponds to /z(T -|T T the temperature in C. of the cathode bars at the outlet point of the bars from the active part of the bottom lining. T the temperature in C. of the cathode bars at their outer ends and A the cross-section in m? of the cathode bars inside the active part of the lining.
-10 (percent) References Cited UNITED STATES PATENTS 3,256,173 6/1966 Schmitt et a1. 204-243 R 2,593,751 4/1952 Grole 204243 M JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 204--243 M, 286
my UNITED I STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 736 Dat d y 9 973 Inventor(s) Hans Bohner et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
In column 2 line 10 "T T" should read ---I Signed and sealed this 29th day of January 1974.
(SEAL) Attest:
EDWARD M FLETCHER JR.
Attesting Officer of Patents
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH658270A CH527909A (en) | 1970-05-01 | 1970-05-01 | Aluminum electrolytic cell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3736244A true US3736244A (en) | 1973-05-29 |
Family
ID=4311871
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00139154A Expired - Lifetime US3736244A (en) | 1970-05-01 | 1971-04-30 | Electrolytic cells for the production of aluminum |
Country Status (13)
| Country | Link |
|---|---|
| US (1) | US3736244A (en) |
| JP (1) | JPS5212130B1 (en) |
| AT (1) | AT308409B (en) |
| BE (1) | BE766066A (en) |
| CA (1) | CA945111A (en) |
| CH (1) | CH527909A (en) |
| FR (1) | FR2088263B1 (en) |
| GB (1) | GB1329191A (en) |
| IS (1) | IS1001B6 (en) |
| NL (1) | NL166504C (en) |
| NO (1) | NO125895B (en) |
| YU (1) | YU34720B (en) |
| ZA (1) | ZA712760B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4210514A (en) * | 1978-02-08 | 1980-07-01 | Aluminum Pechiney | Process for reducing the magnetic disturbances in series of high-intensity electrolysis tanks |
| US11286574B2 (en) | 2016-07-26 | 2022-03-29 | Tokai Cobex Gmbh | Cathode current collector/connector for a Hall-Heroult cell |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2560613B2 (en) * | 1983-05-16 | 1987-03-27 | Pechiney Aluminium | IMPROVEMENT ON CATHODE RATES WITH A METAL SOLE, FOR HALL-HEROULT ELECTROLYSIS TANKS |
| FR2546184B1 (en) * | 1983-05-16 | 1987-01-30 | Pechiney Aluminium | CATHODE ROD WITH A METAL SOLE FOR HALL-HEROULT ELECTROLYSIS TANKS |
-
1970
- 1970-05-01 CH CH658270A patent/CH527909A/en not_active IP Right Cessation
-
1971
- 1971-04-05 NL NL7104524.A patent/NL166504C/en active
- 1971-04-19 GB GB2724671*A patent/GB1329191A/en not_active Expired
- 1971-04-21 BE BE766066A patent/BE766066A/en unknown
- 1971-04-26 IS IS1999A patent/IS1001B6/en unknown
- 1971-04-26 AT AT358471A patent/AT308409B/en not_active IP Right Cessation
- 1971-04-29 ZA ZA712760A patent/ZA712760B/en unknown
- 1971-04-29 NO NO1597/71A patent/NO125895B/no unknown
- 1971-04-29 FR FR7115441A patent/FR2088263B1/fr not_active Expired
- 1971-04-30 YU YU1095/71A patent/YU34720B/en unknown
- 1971-04-30 US US00139154A patent/US3736244A/en not_active Expired - Lifetime
- 1971-05-01 JP JP46029411A patent/JPS5212130B1/ja active Pending
- 1971-05-03 CA CA112,018A patent/CA945111A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4210514A (en) * | 1978-02-08 | 1980-07-01 | Aluminum Pechiney | Process for reducing the magnetic disturbances in series of high-intensity electrolysis tanks |
| US11286574B2 (en) | 2016-07-26 | 2022-03-29 | Tokai Cobex Gmbh | Cathode current collector/connector for a Hall-Heroult cell |
Also Published As
| Publication number | Publication date |
|---|---|
| CH527909A (en) | 1972-09-15 |
| IS1999A7 (en) | 1971-11-02 |
| NO125895B (en) | 1972-11-20 |
| BE766066A (en) | 1971-09-16 |
| IS1001B6 (en) | 1979-01-05 |
| AT308409B (en) | 1973-07-10 |
| FR2088263B1 (en) | 1975-01-17 |
| DE2120888B2 (en) | 1975-09-25 |
| DE2120888A1 (en) | 1971-11-25 |
| FR2088263A1 (en) | 1972-01-07 |
| YU34720B (en) | 1979-12-31 |
| YU109571A (en) | 1979-07-10 |
| NL166504B (en) | 1981-03-16 |
| GB1329191A (en) | 1973-09-05 |
| NL166504C (en) | 1981-08-17 |
| NL7104524A (en) | 1971-11-03 |
| ZA712760B (en) | 1972-01-26 |
| CA945111A (en) | 1974-04-09 |
| JPS5212130B1 (en) | 1977-04-05 |
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