CA1066661A - Cell for fused-salt electrolysis - Google Patents

Cell for fused-salt electrolysis

Info

Publication number
CA1066661A
CA1066661A CA245,571A CA245571A CA1066661A CA 1066661 A CA1066661 A CA 1066661A CA 245571 A CA245571 A CA 245571A CA 1066661 A CA1066661 A CA 1066661A
Authority
CA
Canada
Prior art keywords
anode
cell
support
fused
cover
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
Application number
CA245,571A
Other languages
French (fr)
Inventor
Tomas Arnason
Rudolf Blaska
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcan Holdings Switzerland AG
Original Assignee
Schweizerische Aluminium AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Schweizerische Aluminium AG filed Critical Schweizerische Aluminium AG
Application granted granted Critical
Publication of CA1066661A publication Critical patent/CA1066661A/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/08Cell construction, e.g. bottoms, walls, cathodes
    • C25C3/10External supporting frames or structures
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/22Collecting emitted gases

Landscapes

  • 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)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE:

A cell for fused-salt electrolysis for reducing alumina in the presence of cryolite to metallic aluminum, comprising an insulated tank, which has a carbon bottom, two rows of anode rods, which are disposed on opposite sides of an anode carrier, which is arranged in the longitudinal center plane, an exhaust gas-collecting duct extending at the longitu-dinal center between the two rows of anode rods, and two covers, which are downwardly inclined from the outside of respective rows of anode rods to respective edges of the tank and which are provided each at its outer longitudinal edge and at each of its transverse edges with a skirt that extends as far as to the respective edge of the tank. In this cell each cover is hinged adjacent to its longitudinal edge adjacent to the anodes and at least at its corner portions to a support which extends along the row of anode rods, a carrying arm is firmly secured to each end portion of said support, the carrying arm is pivoted at its other end to the anode carrier and is connected by an operating linkage to a piston rod of a cylinder of a hydraulic or pneumatic actuator, a cylinder of a hydraulic or pneumatic actuator is pivoted to said support at least adjacent to the middle thereof, and the piston rod of the last-mentioned actuator engages the cover. This electrolyc cell can be operated in a simple manner by a manipulator; the molten material can be removed without obstruction and the anode can be replaced without difficulties.

Description

'"` 1066~
.
The present invention relates to a cell for fused-salt - electrolysis and is particular to a cell for fused-salt elec-trolysis for reducing alumina in the presence of cryolite to metallic aluminum, comprising an insulated tank, which has a carbon bottom, two rows of anode rods, which are disposed on opposite sides of an anode carrier, which is arranged in the longitudinal center plane, an exhaust gas-collecting duct extending at the longitudinal center between the two rows of anode rods, and two covers, which are downwardly inclined from the outside of respective rows of anode rods to respective longitudinal edges of the tank and which are provided each at its outer longitudinal edge and at each of its transverse edges with a skirt than extends as far as to the respective edge of the tank.
The exhaust gases formed in the electrochemical process of recovering aluminum from alumina contain fluorine, which is a product of the reaction of the cryolite in the elec-trolytic cell, and finely divided carbon, which released by the carbon anodes. For ecological reasons, it is essential to reduce particularly the fluorine content in the exhaust gases to the utmost minimum before such gases are discharged into ~.
the atmosphere so that the environment is not adversely affected.
It is known for this purpose to purify the exhaust air which escapes from the buildings which contain plants for fused-salt electrolysis - this air contains the exhaust gases -and then to discharge the air in an ecologically innocuous state. To this end the natural chimney action in the building is utilized to move the air in the buildings, which contains the exhaust gases from the electrolysis, to mechanical means, such as blowers, purifiers or the like, which are mounted on the roofs and serve to discharge the emissions. The purifiers consist essentially of liquid-wetted filters, between which a mist is maintained so that dust particles an gaseous --- ~06666~

constituents are retained by the filters and by the liquid particles and the purified air is discharged into the atmosphere.
Whereas the mechanical means which are available at present can handle and purify all air in the buildings, they do not decisively improve the conditions within the building from the aspect of work hygiene.
To ~aintain the concentration of the noxious exhaust gases which escape from the cells for fused-salt electrolysis - 10 within tolerable limits, it is known to provide the cells for .. . .
fused-salt electrolysis with a cover. This cover consists of a collecting duct, which extends longitudinally between the rows of anode rods and which is provided at its outer periphery - with two cover plates, which are downwardly inclined toward the longitudinal side of the tank. The anode rods extend through ~ the cover plates and those edge portions of the cover plates ; which are near the longitudinal sides of the tank closely embrace the anode blocks so that an uncovered surface of the eleotrolytic cell remains exposed between the inside periphery of the tank and the outside edge of the cover plates and permits o~ an access to the interior of the cell whereas the exhaust gases from the cell can be sucked off only from a relatively small part thereof.
It is known to eliminate this disadvantage by the use of a cell for fused-salt electrolysis in which the cover plates are mounted on a tube which is longitudinally bisected and -which engages the upper portion of the periphery of the cylindrical exhaust gas-collecting duct. Hinged plates are mounted at the outside edges of the cover plates and rest on the longitudinal edges of the tank. The rate at which exhaust gases escape into the air in the building is much reduced by this arrangement.
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On the other hand, the arrangement has the - ~
disadvantage that these means muat be entirely removed a ;
remplacement of the anode.
; For this reason it has been proposed (Opened German Specification 2,251,898) so to design to cover that the same must be opened only when it is desired to charge the cell and to remove the molten aluminum. This object is accomplished in that the cover covers the anodes on their vertically extending sides, transverse walls intended to rest on the ends of the tank are mounted on the cover, and the anodes consist of continuous anodes. This arrangement i not highly suitable where so-called manipulators are to be used, which can, e.g., automatically break up the slag crust, and feed the alumina to the cell, -Besides, the arrangement requires the use of continuous anodes.
It is an object of the invention to provide a cell for fused-salt electrolysis with covers which are so designed that the electrolytic cell can be operated in a simple manner by a manipulator, the molten material can be removed without obatruction, the anodes can be replaced without special difficulties, and particularly tight covers are also provided.
This object i~ accomplished in that each cover is hinged adjacent to its longitudinal edge adjacent to the anodes and at least at its corner portions to a support which extends along the row of anode rods, a carrying arm is firmly secured to each end portion of the support, the carrying arm is pivoted at its other end to the anode carrier and is connected by an operating linkage to a piston rod of a cylinder of a first - hydraulic or pneumatic actuator. A cylinder of a second hydraulic or pneumatic actuator is pivoted to the support at least adjacent to the middle thereof, and the piston rod of the last-mentioned actuator engages the cover.
-3-~. , ' .
, ~066661 Because the entire anode carrier descends slowly as the anodes are consumed, the fixation of the bearing bracket to the anode carrier ensures that there will be no relative movement between the anode carrier and the cover so that the struc,ture is very tight.
The second actuator is operable to impart a sufficient upward pivotal movement to the cover when it is desired to ' charge the cell for fused-salt electrolysis and to remove the molten aluminum.

1 As above mentioned each carrying arm is engaged by ; an operating linkage, which is connected to the piston rod of a first pneumatic actuator having a cylinder secured to the , anode carrier. When it is desired to replace the anodes, this arrangement may be used to impart a further pivotal movement to the previously raised cover so that the anodes can be rendered accessible in a simple manner.
The cover may be suitably secured by means of a plu-rality of brackets to the preferably tubular support. The ,~ piston rod of'the actuator which is disposed adjacent to the middle of the support and serve~ to move the cover may be con-nected to such bracket.
According to a special feature of the invention, U-shaped anode rod seals are disposed on that side of the support which faces the exhaust gas-collecting duct, which extends as far as to the anode rods, and these seals embrace the anode rods and positively engage the same so that the ~' -seals can adjust themselves to the instantaneous position of the anode, rods, which is not exactly fixed. ~, Each anode rod seal consists of a sliding element, which'positively embraces the anode rod and which is horizontal-ly slidably ~ounted in a guide whic,h is mounted on a baseplate.

The apparatusaccording to theinventionisshownbywayof exampleonthedrawingand willbe explained more fully hereinafter.

,' 4 , 10666~1 Fig. 1 is a front elevation showing the cover in closed position.
Fig. 2 is a side elevation showing the cover in closed position.
Fig. 3 shows a slidable anode rod seal.
Fig. 4 is a side elevation showing the anode rod seal.
An anode carrier 3 carrying anode rods 2 is disposed over the cell 1 for fused-salt electrolysis and extends in the longitudinal center plane of said cell. A rectangular exhaust
4~ .
gas-collecting duct 4 is disposed between the two rows of anodes.
A covers plate 5 is downwardly inclined from each row of anode rods to the longitudinal edge of the electrolytic cell 1.
Skirts 6 of asbestos are mounted on the longitudinal edge and the end edges of each cover 5 and rest on the longitudinal edge and the end edges of the electrolytic cell 1 and prevent an escape of exhaust gases adjacent to these edges. Brackets 7 are secured to cover 5 at that longitudinal edge thereof which is near the anodes and serve to hinge the respective covers 5 to a support tube 8. Carrying arms are secured to respective end portions of the support tube 8. ~he other end of each carrying arm is pivoted to a bearing bracket 10, which is mounted on the anode carrier 3. A composite operating linkage 11 is connected to the carrying arm 9 and to the piston rod of a pneumatic actuator, the cylinder 12 of which i9 mounted on the anode carrier 3. An abutment 14 is mounted in the middle of the ~upport tube 8. ~he end of the cylinder 13 of a pneumatic actuator is pivoted to the abutment 14. Ihe piston rod of said actuator is pivoted to a bracket 7, which is mounted on the cover 5. Pivotal movements I and II, respectively, are imparted to the cover by the actuators comprising the cylinders 1~ and 12.

lhe arrangement according to the invention permits of - . , : , ' '' ' ' :
. . . : ~ .
, ~066661 a control of each eover in such a manner that the pneurnatic actuator comprising the cylinder13 is operated to impart an upward pivotal movement to the cover 5 when it is desired to perform general operations in the cell, such as breaking erusts, eharging alumina, ladling molten metal and checking the cells. For a replacement of anodes, a further upward pivotal movement, beyond the vertical position, is imparted to the previously raised cover 5 about the pivotal axis of the carrying arm 9.
Figs. 3 and 4 show the seals between the anode rods , and the cover. ~he anode rod 2 is positively embraced by a horizontally slidable element 15, whieh is slidably mounted in -a guide 16 on a baseplate 17. lhe baseplate is secured to the supporting tube 8 and direetly engages the anode earrier 3.
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Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A cell for fused-salt electrolysis for reducing alumina in the presence of cryolite to metallic aluminum, comprising an insulated tank, which has a carbon bottom, two rows of anode rods, which are disposed on opposite sides of an anode carrier, which is arranged in the longitudinal center plane, an exhaust gas-collecting duct extending at the longitu-dinal center between the two rows of anode rods, and two covers, which are downwardly inclined from the outside of respective rows of anode rods to respective edges of the tank and which are provided each at its outer longitudinal edge and at each of its transverse edges with a skirt that extends as far as to the respective edge of the tank, characterized in that each cover is hinged adjacent to its longitudinal edge adjacent to the anodes and at least at its corner portions to a support which extends along the row of anode rods, a carrying arm is firmly secured to each end portion of said support, the carrying arm is pivoted at its other end to the anode carrier and is connected by an operating linkage to a piston rod of a cylinder of a first hydraulic or pneumatic actuator, a cylinder of a second hydraulic or pneumatic actuator is pivoted to said support at least adjacent to the middle thereof, and the piston rod of the last-mentioned actuator engages the cover.
2. A cell for fused-salt electrolysis according to claim 1, characterized in that each cover is hinged by a plurality of brackets to the support.
3. A cell for fused-salt electrolysis according to claim 2, characterized in that the support is tubular.
4, A cell for fused-salt electrolysis according to claims 1 and 2, characterized in that the cylinder of the second hydraulic or pneumatic actuator is connected to an abutment mounted on the support.
5. A cell for fused-salt electrolysis according to claim 1, characterized in that U-shaped anode seals are secured to the support on the side thereof adjacent to the anode and positively embrace the anodes.
6. A cell for fused-salt electrolysis according to claim 5, characterized in that the anode seal consists of a slidable member, which is horizontally slidable in a guide mounted on a baseplate, which is connected to the support.
CA245,571A 1975-03-10 1976-02-11 Cell for fused-salt electrolysis Expired CA1066661A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2510400A DE2510400C2 (en) 1975-03-10 1975-03-10 Melt flow electrolysis cell

Publications (1)

Publication Number Publication Date
CA1066661A true CA1066661A (en) 1979-11-20

Family

ID=5940940

Family Applications (1)

Application Number Title Priority Date Filing Date
CA245,571A Expired CA1066661A (en) 1975-03-10 1976-02-11 Cell for fused-salt electrolysis

Country Status (11)

Country Link
JP (1) JPS51112716A (en)
AT (1) AT349769B (en)
BE (1) BE839336A (en)
CA (1) CA1066661A (en)
DE (1) DE2510400C2 (en)
FR (1) FR2303869A1 (en)
GB (1) GB1526841A (en)
IT (1) IT1056863B (en)
NL (1) NL7514534A (en)
NO (1) NO143914C (en)
SE (1) SE412075B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4202753A (en) * 1979-04-23 1980-05-13 Swiss Aluminium Ltd. Reduction cell hood

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2263349A1 (en) * 1972-12-23 1974-07-04 Siemag Translift Gmbh Aluminium furnace for electrolysis in fused salts - fitted with sectional hoods over bath each with own actuating cylinder
DE2330557B2 (en) * 1973-06-15 1976-09-16 Wolgogradskij Aljuminiewyj Sawod, Wolgograd (Sowjetunion) COVER OF AN ELECTROLYSIS CELL WITH PRE-FIRED ELECTRODES FOR THE EXTRACTION OF ALUMINUM

Also Published As

Publication number Publication date
JPS51112716A (en) 1976-10-05
NO143914C (en) 1981-05-06
NL7514534A (en) 1976-09-14
FR2303869A1 (en) 1976-10-08
DE2510400A1 (en) 1976-09-30
SE412075B (en) 1980-02-18
DE2510400C2 (en) 1985-08-08
FR2303869B1 (en) 1980-01-04
GB1526841A (en) 1978-10-04
ATA895975A (en) 1978-09-15
NO143914B (en) 1981-01-26
NO753907L (en) 1976-09-13
SE7602868L (en) 1976-09-13
AT349769B (en) 1979-04-25
IT1056863B (en) 1982-02-20
BE839336A (en) 1976-09-08

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