EP0041045B1 - Cathode pour cellule d'électrolyse ignée - Google Patents

Cathode pour cellule d'électrolyse ignée Download PDF

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Publication number
EP0041045B1
EP0041045B1 EP81810185A EP81810185A EP0041045B1 EP 0041045 B1 EP0041045 B1 EP 0041045B1 EP 81810185 A EP81810185 A EP 81810185A EP 81810185 A EP81810185 A EP 81810185A EP 0041045 B1 EP0041045 B1 EP 0041045B1
Authority
EP
European Patent Office
Prior art keywords
cathode
aluminum
cathode according
aluminium
elements
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
EP81810185A
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German (de)
English (en)
Other versions
EP0041045A1 (fr
Inventor
Tibor Kugler
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
Priority to AT81810185T priority Critical patent/ATE3884T1/de
Publication of EP0041045A1 publication Critical patent/EP0041045A1/fr
Application granted granted Critical
Publication of EP0041045B1 publication Critical patent/EP0041045B1/fr
Expired legal-status Critical Current

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    • 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

  • the invention relates to a cathode made of individually replaceable elements for a melt flow electrolysis cell, in particular for the production of aluminum.
  • cathodes made of titanium diboride, titanium carbide, pyrolytic graphite, boron carbide and other substances are proposed for electrolytic cells belonging to the prior art, mixtures of these substances which can be sintered together also being used.
  • cathodes that can be wetted with aluminum and are not or only slightly soluble in aluminum offer decisive advantages.
  • the cathodically deposited aluminum already flows when a very thin layer is formed on the cathode surface facing the active anode surface. It is therefore possible to remove the deposited liquid aluminum from the gap between the anode and cathode and to feed it to a sump located outside the gap.
  • the irregularities with respect to the thickness of the aluminum layer which are well known from conventional electrolysis, do not form - under the influence of electromagnetic and convectional forces. Therefore, the interpolar distance can be reduced without sacrificing current efficiency, i.e. H. a significantly lower energy consumption per unit of reduced metal is achieved.
  • connection between the carbon base and the wettable cathode plates places difficult demands on the connection mass and increases the electrical resistance of the cell base.
  • the cell bottom is made of electrically conductive, ie weakly heat-insulating carbon material.
  • Wettable cathodes are also used according to the process of DE-OS 26 56 579.
  • the circulation of the cryolite melt is improved in that the cathode elements are anchored in the electrically conductive cell bottom and protrude in the area below the anodes from the aluminum sump collected on the entire remaining cell bottom surface.
  • the cathode elements consist of tubes, closed at the bottom, made of aluminum-wettable material, the tubes being completely filled with aluminum.
  • gaps between the cathode elements facilitate the circulation of the electrolyte.
  • the height of these gaps or tubes is chosen so that there is no significant current transfer between the anode and the aluminum sump.
  • the power supply lines to the cathode elements shown in the examples of the above-mentioned DE-OS all have the disadvantages of power supply through the carbon base.
  • the flow of the electrolyte is a vortex flow around the cathode element and takes place without a preferred direction, so the distribution of the alumina concentration is not optimal.
  • a major disadvantage of all of these previously discussed embodiments with wettable cathodes is that they are firmly anchored in the carbon bottom of the cell.
  • a material must therefore be selected for the wettable cathodes whose lifespan is at least the same or better than the operating life of the cell lining. This would result in the use of a cheaper material with a shorter operating time or a simpler manufacturing technology. that failure of only a small part of the cathode elements, for example due to operating or manufacturing errors, would result in failure of the entire electrolytic cell.
  • the carbon floor with the cast-in cathode bars is in itself extremely sensitive to manufacturing defects.
  • the inventor has set himself the task of creating a cathode from individually interchangeable elements for a melt flow electrolysis cell for the production of aluminum, which can be produced more economically, in particular with regard to shaping and processing.
  • the upper parts of the elements consist of materials described in the relevant literature for wettable cathode plates which meet the requirements. Examples include titanium diboride, titanium carbide, titanium nitride, zirconium diboride, zirconium carbide, zirconium nitride and mixtures of two or more materials, which may optionally contain a small amount of mixed boron nitride.
  • the electrically conductive, preferably plate-shaped upper parts of the elements protrude into the liquid aluminum, but they do not touch the carbon bottom of the cell.
  • the lower parts of the elements or their coating need not be wettable by aluminum or have electrical conductivity. They only have to be compatible with molten aluminum, have sufficient mechanical strength and high thermal shock resistance. Materials that meet these conditions sufficiently are much cheaper than those used for the upper parts or their coating, which are wettable by aluminum and. electrically conductive materials.
  • molded parts made of insulator material used for the lower part of the elements are much easier to manufacture, which - together with the lower production costs for the materials - is expressed in the fact that mass production of lower parts is 10 to 20 times cheaper than that of upper parts.
  • insulator materials that never come into contact with the molten electrolyte include highly sintered aluminum oxide, aluminum oxide-containing ceramics, silicon carbide or silicon nitride-bonded silicon carbide. These materials have a higher specific weight than aluminum and are erosion-resistant, which is important because of the sludge present in the circulating aluminum.
  • Both the lower and the upper part of a cathode element can - instead of being designed as a homogeneous solid body - a core made of a less expensive, mechanically stable material, such as. B. steel, titanium or graphite, which is coated by a known method with at least one of the corresponding materials. If graphite is used as the core material, the composite body can be produced using a sintering process.
  • the cathode elements preferably consist of several sub-elements.
  • the electrically conductive sub-elements forming the upper part are expediently of the simplest possible geometric shape, for. B. 1-2 cm thick, vertically arranged plates, the distance between the plates being greater than their thickness.
  • the easily formable and editable sub-elements made of insulating material forming the lower part form a support or a support structure for the upper sub-elements.
  • the horizontal surface dimensions of the cathode elements are expediently designed in such a way that an integer multiple between 1 and 7 corresponds to the horizontal surface dimensions of the anode above.
  • the horizontal geometric dimensions of a cathode element and the corresponding anode of the same order of magnitude are preferred.
  • the type of power supply from the power source to the cathode surface is of crucial importance for the furnace operation: the electrolyte located between the anode and the cathode element is exposed to a magnetohydrodynamic pumping action under the influence of the electrolytic current and the magnetic field.
  • FIGS. 1-3 A cathode element 10 with an upper part made of the electrically conductive aluminum-wettable plates 12 and a lower part made of aluminum-compatible shaped plates 14, 16 is shown in FIGS. 1-3.
  • the wettable cathode plates 12 are mechanically stably connected to insulator plates 14 of the same dimensions by means of round bolts 18.
  • the bolts 18 are preferably made of the more easily machinable and cheaper insulator material; they do not come into contact with the molten electrolyte.
  • the support plates 14 made of insulator material have recesses 20 on their underside, which in turn fit in a form-fitting manner in recesses 22 of the support plates 16 likewise made of insulator material.
  • a mechanically stable cathode element 10 is formed with simple means, in which a group of cathode plates 12 which can be wetted by aluminum is joined to form a unit by means of a support structure made of much cheaper material.
  • the mass of this cathode element 10 is large enough not to be displaced or carried away by the bath currents.
  • intermediate pieces e.g. B. in the form of wedges, and / or cements resistant to liquid aluminum can be used.
  • the elements can also adapt adequately to thermal expansions afterwards.
  • the electrically conductive cathode plates 12 have the interpolar distance d from the burning carbon anode 28. During the electrolysis process, the electrolyte is quickly used up in a narrow gap between the cathode plates and the anode.
  • the cathode plates 12 are relatively narrow; therefore, the bath flow can rapidly renew the electrolyte depleted in aluminum oxide in the interpolar gap, even if the value is greatly reduced compared to the normal value of 6-6.5 cm for d.
  • the deposited metal forms an uninterrupted film on the wettable cathode plates 12 and flows down to the metal sump 26.
  • the surface 32 of the liquid aluminum 26 must always lie in the area of the wettable cathode plates 12, in particular when scooping, this metal level must never sink into the area of the insulator plates 14, 16. This would be both a power cut and corrosive Destruction of the insulator plates mean.
  • the direct electrolysis current flows from the anodes 28 via the electrolytes 30 in the interpolar gap to the cathode plates 12, then passes into the liquid aluminum 26 and finally flows via the carbon bottom 34 into the iron cathode bars 36.
  • Guide grooves 35 can be formed in the carbon base 34 of the electrolytic cell, which prevent the cathode elements 10 from slipping sideways.
  • the plate 12 has a dovetail 40 which can be inserted into a corresponding recess in the carrier plate 14.
  • the support structure made of insulator material is then designed so that the plates cannot be moved laterally.
  • FIG. 5 Another variant of wettable cathode plates 12 is shown in FIG. 5. Both the formation of a window 38 and the bevelled underside are intended on the one hand to save wettable cathode material and on the other hand to optimize the flow conditions in the bath.
  • the cathode plate 12 is fastened in a support plate 14 by means of an extension 42 directed downwards in the center.
  • a support structure 14, 16 per se is not the subject of the invention; any suitable variant used in other fields of technology can be used for this purpose.
  • the cathode elements 10 according to the invention can also be used to convert existing electrolysis cells by simply placing units adapted to the anode dimensions and the metal level on the carbon floor. As a result, the interpolar distance can be reduced at low additional costs, and the current yield can thereby be increased. In particular, it should be noted that the retrofitting can be carried out without decommissioning the electrolytic cell and that subsequent replacement of defective cathode elements does not pose any problems.

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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)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Immobilizing And Processing Of Enzymes And Microorganisms (AREA)
  • Conductive Materials (AREA)

Claims (10)

1. Cathode constituée d'éléments remplaçables séparément pour une cuve d'électrolyse ignée destinée à la fabrication d'aluminium, caractérisée en ce que les éléments (10) sont composés de deux parties, faites de matériaux différents, qui résistent aux chocs thermiques et sont mécaniquement assemblées rigidement entre elles : une partie supérieure (12) située à la fois dans l'électrolyte fondu (30) et dans l'aluminium déposé (26) et une partie inférieure (14, 16) située uniquement dans l'aluminium liquide (26),
- la partie supérieure (12) ou son revêtement étant en matériau bon conducteur électrique à la température de travail, résistant chimiquement et mouillable par l'aluminium,
- et la partie inférieure (14, 16) ou son revêtement étant en matériau isolant résistant à l'aluminium liquide.
2. Cathode selon la revendication 1, caractérisée en ce que la partie supérieure des éléments (10) est formée de plaques (12) disposées verticalement et dont le dessus horizontal s'étend de préférence sur toute l'étendue de la surface de travail de l'anode (28) correspondante.
3. Cathode selon la revendication 2, caractérisée en ce que l'écartement entre les plaques (12) est plus grand que leur épaisseur.
4. Cathode selon l'une des revendications 1 à 3, caractérisée en ce que les éléments (10) sont stabilisés davantage par des pièces intermédiaires et/ou par des ciments qui résistent à l'aluminium liquide.
5. Cathode selon au moins une des revendications 1 à 4, caractérisée en ce qu'un élément (10) possède une aire de surface horizontale qui correspond à un multiple entier compris entre 1 et 7 de l'aire de surface horizontale de l'anode (28) située au-dessus.
6. Cathode selon au moins une des revendications 1 à 5, caractérisée en ce que des fenêtres (38) sont ménagées dans les plaques cathodiques (12) électriquement conductrices.
7. Cathode selon au moins une des revendications 1 à 6, caractérisée en ce que les parties supérieures (12) et/ou inférieures (14, 16) possèdent un noyau en acier, titane ou graphite qui est revêtu d'au moins un matériau ayant les propriétés nécessaires.
8. Cathode selon au moins une des revendications 1 à 7, caractérisée en ce que la partie supérieure (12) ou son revêtement est en diborure de titane, carbure de titane, nitrure de titane, diborure de zirconium, carbure de zirconium, nitrure de zirconium ou un mélange de ces matériaux.
9. Cathode selon la revendication 8, caractérisée en ce que le matériau de la partie supérieure (12) ou de son revêtement contient une faible quantité ajoutée en mélange de nitrure de bore.
10. Cathode selon au moins une des revendications 1 à 9, caractérisée en ce que la partie inférieure (14, 16) ou son revêtement est en oxyde d'aluminium fritté de finition, matériau céramique contenant de l'oxyde d'aluminium, carbure de silicium ou carbure de silicium lié au nitrure de silicium.
EP81810185A 1980-05-23 1981-05-15 Cathode pour cellule d'électrolyse ignée Expired EP0041045B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81810185T ATE3884T1 (de) 1980-05-23 1981-05-15 Kathode fuer eine schmelzflusselektrolysezelle.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH4038/80 1980-05-23
CH403880 1980-05-23

Publications (2)

Publication Number Publication Date
EP0041045A1 EP0041045A1 (fr) 1981-12-02
EP0041045B1 true EP0041045B1 (fr) 1983-06-22

Family

ID=4268652

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81810185A Expired EP0041045B1 (fr) 1980-05-23 1981-05-15 Cathode pour cellule d'électrolyse ignée

Country Status (14)

Country Link
US (1) US4376690A (fr)
EP (1) EP0041045B1 (fr)
JP (1) JPS5719391A (fr)
AT (1) ATE3884T1 (fr)
AU (1) AU543106B2 (fr)
BR (1) BR8103210A (fr)
CA (1) CA1163601A (fr)
DE (1) DE3160478D1 (fr)
ES (1) ES502372A0 (fr)
IS (1) IS1170B6 (fr)
NO (1) NO155104C (fr)
NZ (1) NZ197038A (fr)
YU (1) YU132181A (fr)
ZA (1) ZA813338B (fr)

Families Citing this family (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2508496B2 (fr) * 1981-02-24 1985-09-20 Pechiney Aluminium Elements cathodiques amovibles en refractaire electroconducteur pour la production d'aluminium par le procede hall-heroult
ZA824254B (en) * 1981-06-25 1983-05-25 Alcan Int Ltd Electrolytic reduction cells
US4526669A (en) * 1982-06-03 1985-07-02 Great Lakes Carbon Corporation Cathodic component for aluminum reduction cell
CH655136A5 (de) * 1983-07-27 1986-03-27 Alusuisse Zelle zur elektrolytischen reinigung von aluminium.
US4450054A (en) * 1983-09-28 1984-05-22 Reynolds Metals Company Alumina reduction cell
FR2565258B1 (fr) * 1984-05-29 1986-08-29 Pechiney Aluminium Anode carbonee a rondins partiellement retrecis destinee aux cuves pour la production d'aluminium par electrolyse
JPS60261312A (ja) * 1984-06-07 1985-12-24 三菱電機株式会社 複合ガス開閉装置
US4707239A (en) * 1986-03-11 1987-11-17 The United States Of America As Represented By The Secretary Of The Interior Electrode assembly for molten metal production from molten electrolytes
NO883130L (no) * 1987-07-14 1989-01-16 Alcan Int Ltd Foring for aluminium reduksjonscelle.
US4919782A (en) * 1989-02-21 1990-04-24 Reynolds Metals Company Alumina reduction cell
DE69120081D1 (de) * 1990-08-20 1996-07-11 Comalco Alu Aluminium-schmelzzelle ohne wandschutz durch den festen elektrolyten
US5129998A (en) * 1991-05-20 1992-07-14 Reynolds Metals Company Refractory hard metal shapes for aluminum production
DE4118304A1 (de) * 1991-06-04 1992-12-24 Vaw Ver Aluminium Werke Ag Elektrolysezelle zur aluminiumgewinnung
US6001236A (en) * 1992-04-01 1999-12-14 Moltech Invent S.A. Application of refractory borides to protect carbon-containing components of aluminium production cells
US5310476A (en) * 1992-04-01 1994-05-10 Moltech Invent S.A. Application of refractory protective coatings, particularly on the surface of electrolytic cell components
US5651874A (en) * 1993-05-28 1997-07-29 Moltech Invent S.A. Method for production of aluminum utilizing protected carbon-containing components
US5413689A (en) * 1992-06-12 1995-05-09 Moltech Invent S.A. Carbon containing body or mass useful as cell component
WO1994024337A1 (fr) * 1993-04-19 1994-10-27 Moltech Invent Sa Composants cathodiques traites, a base de carbone ou en carbone pour des cellules de production d'aluminium
US5679224A (en) * 1993-11-23 1997-10-21 Moltech Invent S.A. Treated carbon or carbon-based cathodic components of aluminum production cells
US5409593A (en) * 1993-12-03 1995-04-25 Sifco Industries, Inc. Method and apparatus for selective electroplating using soluble anodes
EP0905284B1 (fr) * 1994-09-08 2002-04-03 MOLTECH Invent S.A. Cuve d'électrolyse d'aluminium à cathode drainée
US5472578A (en) * 1994-09-16 1995-12-05 Moltech Invent S.A. Aluminium production cell and assembly
US5753163A (en) * 1995-08-28 1998-05-19 Moltech. Invent S.A. Production of bodies of refractory borides
US6719890B2 (en) * 2002-04-22 2004-04-13 Northwest Aluminum Technologies Cathode for a hall-heroult type electrolytic cell for producing aluminum
AUPS212802A0 (en) * 2002-05-03 2002-06-06 Mount Isa Mines Limited Reducing power consumption in electro-refining or electro- winning of metal
US20110114479A1 (en) * 2009-11-13 2011-05-19 Kennametal Inc. Composite Material Useful in Electrolytic Aluminum Production Cells
DE102010039638B4 (de) * 2010-08-23 2015-11-19 Sgl Carbon Se Kathode, Vorrichtung zur Aluminiumgewinnung und Verwendung der Kathode bei der Aluminiumgewinnung
US8501050B2 (en) 2011-09-28 2013-08-06 Kennametal Inc. Titanium diboride-silicon carbide composites useful in electrolytic aluminum production cells and methods for producing the same
US11203814B2 (en) 2016-03-30 2021-12-21 Alcoa Usa Corp. Apparatuses and systems for vertical electrolysis cells

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4071420A (en) * 1975-12-31 1978-01-31 Aluminum Company Of America Electrolytic production of metal
NO764014L (fr) * 1975-12-31 1977-07-01 Aluminum Co Of America
US4093524A (en) * 1976-12-10 1978-06-06 Kaiser Aluminum & Chemical Corporation Bonding of refractory hard metal
CH635132A5 (de) * 1978-07-04 1983-03-15 Alusuisse Kathode fuer einen schmelzflusselektrolyseofen.
US4177128A (en) * 1978-12-20 1979-12-04 Ppg Industries, Inc. Cathode element for use in aluminum reduction cell
US4231853A (en) * 1979-04-27 1980-11-04 Ppg Industries, Inc. Cathodic current conducting elements for use in aluminum reduction cells

Also Published As

Publication number Publication date
NZ197038A (en) 1984-04-27
BR8103210A (pt) 1982-02-16
CA1163601A (fr) 1984-03-13
NO155104C (no) 1987-02-11
YU132181A (en) 1983-06-30
AU7029981A (en) 1981-11-26
EP0041045A1 (fr) 1981-12-02
ES8203989A1 (es) 1982-04-01
DE3160478D1 (en) 1983-07-28
US4376690A (en) 1983-03-15
ES502372A0 (es) 1982-04-01
IS1170B6 (is) 1984-12-28
ZA813338B (en) 1982-05-26
NO155104B (no) 1986-11-03
IS2641A7 (is) 1981-11-24
AU543106B2 (en) 1985-04-04
NO811711L (no) 1981-11-24
ATE3884T1 (de) 1983-07-15
JPS5719391A (en) 1982-02-01

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