EP0091914A1 - Cathode de cellule d'electrolyse de masse en fusion pour la preparation d'aluminium. - Google Patents

Cathode de cellule d'electrolyse de masse en fusion pour la preparation d'aluminium.

Info

Publication number
EP0091914A1
EP0091914A1 EP82902974A EP82902974A EP0091914A1 EP 0091914 A1 EP0091914 A1 EP 0091914A1 EP 82902974 A EP82902974 A EP 82902974A EP 82902974 A EP82902974 A EP 82902974A EP 0091914 A1 EP0091914 A1 EP 0091914A1
Authority
EP
European Patent Office
Prior art keywords
solid
cathode
aluminum
open
cathode according
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.)
Granted
Application number
EP82902974A
Other languages
German (de)
English (en)
Other versions
EP0091914B1 (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
Alusuisse Holdings AG
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 Alusuisse Holdings AG, Schweizerische Aluminium AG filed Critical Alusuisse Holdings AG
Priority to AT82902974T priority Critical patent/ATE15079T1/de
Publication of EP0091914A1 publication Critical patent/EP0091914A1/fr
Application granted granted Critical
Publication of EP0091914B1 publication Critical patent/EP0091914B1/fr
Expired legal-status Critical Current

Links

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
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes

Definitions

  • the invention relates to a wettable solid-state cathode which can be used in a melt-flow electrolysis cell for the production of aluminum and has an aluminide of at least one transition metal from groups IVA, VA and VIA of the periodic system of the elements.
  • the electrolysis generally takes place in a temperature range of about 940 to 970 ° C.
  • the electrolyte becomes poor in aluminum oxide.
  • the anode effect occurs, which results in an increase in voltage from, for example, 4 to 4.5 V to 30 V and above.
  • the aluminum oxide concentration must be increased by adding new aluminum oxide (alumina).
  • Cathodes made of titanium diboride, titanium carbide, pyro-graphite, boron carbide and other substances are known to use wettable solid-state cathodes in the melt flow electrolysis for the production of aluminum.
  • Cathodes made of titanium diboride, titanium carbide, pyro-graphite, boron carbide and other substances are known to use wettable solid-state cathodes in the melt flow electrolysis for the production of aluminum.
  • OMP beaten mixtures which, for example, can be sintered together, are also used.
  • the usual interpolar distance of approximately 5 cm can be reduced as far as the other parameters allow, for example circulation of the electrolyte in the interpolar gap and maintenance of the electrolysis temperature.
  • the reduced interpolar distance results in a significantly reduced energy consumption and avoids the formation of non-uniformities in relation to the thickness of the aluminum layer.
  • DE-OS 28 38 965 shows solid body cathodes made of individually interchangeable elements, each with at least one power supply.
  • the interchangeable elements are arranged from two mechanically rigidly connected parts that are resistant to thermal shock - an upper part protruding from the molten electrolyte into the separated aluminum and an exclusion cloth in the liquid aluminum lower part - made of different materials.
  • the upper part at least in the area of the surface, remains unchanged from aluminum-wettable material, while the lower part or its coating consists of an insulator material that is resistant to the liquid aluminum.
  • DE-OS 30 45 349 relates to an exchangeable wettable solid-state cathode, which consists of an aluminide of at least one metal from the group formed from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten, without binding phase made of metallic aluminum.
  • the non-aluminum components of the aluminide thus belong to group III A, IV A and / or VI A of the periodic system of the elements.
  • the solubility of a metallic non-aluminum component of the aluminide in the liquid aluminum is approximately 1%.
  • the cathode elements are therefore alloyed until the liquid aluminum deposited is saturated with one or more of the transition metals in the aluminide.
  • the aluminides which have been removed during the electrolysis process are recovered from the deposited metal by cooling it to approximately 700 ° C.
  • the crystallizing aluminide can be removed from the liquid metal by known means and used again for the production of cathode elements. This creates a material cycle with relatively low losses.
  • the inventor has set himself the task of creating solid-state cathodes working on the basis of aluminides with a service life which corresponds to one or more anode service lives, with the purchase price of the cathode and the handling costs being to be substantially reduced.
  • the object is achieved in that the solid-state cathode essentially consists of a support body and an open-pore one located at least in the region of the working surface. structure impregnated with transition metal / s saturated aluminum, which can be fed continuously from aluminide supplies.
  • the working surface is the surface which, when the cathode is inserted in the electrolytic cell, points in the direction of the anode and the direct electrical current . will flow through.
  • the aluminum ions are reduced to elemental aluminum on this work surface.
  • the working surfaces of the cathodes are therefore expediently slightly inclined so that the deposited aluminum, which forms a film on the wettable cathode, can measure off.
  • the working surfaces of the corresponding anodes which e.g. can consist of combustible carbon or incombustible oxide ceramics are inclined accordingly. This tendency also has an advantageous effect here: the oxygen or CO2 which is formed can escape better from the molten electrolyte.
  • the open-pore structure is anchored on the support body or part of it. If this support body consists of an electrically non-conductive material, the open-pore structure impregnated with aluminum saturated with transition metal / s must reach at least to the liquid metal when the solid cathode is inserted, so that the electrical current through this impregnation alloy and possibly through the structure can
  • the support body therefore preferably consists at least partially of a material which is highly electrically conductive at 900 to 1000 ° C. and is resistant to the melt flow. In this case, the current can mainly flow through the support body. Apart from the electrical conductivity, it is essential that the material of the support body is cheap and easy to form. For these reasons, carbon is particularly well suited for the supporting body.
  • the cathode is always in the case of manipulations on the traverse or the anode bar and in particular when changing the anodes
  • the solid-state cathodes are therefore preferably designed as individually replaceable elements which stand on the cell bottom. Damaged elements can be quickly replaced.
  • the risk of damage can be significantly reduced if the solid-state cathodes are designed as elements which float in the melt flow and have lateral spaces.
  • the molten electrolyte has a density of 2.1 g / cm.3
  • the liquid aluminum has a density of 2.3 g / cm ⁇ .
  • the density of a floating cathode must be between these two values.
  • the density of the cathode material used is too low, appropriate pieces of iron can be used, but these must be evenly distributed and completely encased by the cathode material.
  • the weight of the pieces of iron to be used is calculated so that the apparent density of the entire solid cathode is between 2.1 and 2.3 g / cm 3 .
  • the density of the cathode material used is too high, correspondingly closed cavities are formed in the cathode material.
  • Solid cathodes with the correct density float like fins in the liquid aluminum; they are preferably held at the desired distance from one another and from the cell shelf by appropriately designed spacers.
  • the open-pore structure on the one hand must be sufficiently permeable to the aluminum saturated with transition metal / s, but on the other hand it must not allow it to flow out without resistance.
  • the optimal solution must be sought, taking capillary and surface forces into account.
  • This fiber structure is expediently designed in the form of a felt or a fabric.
  • the fibers are a few micrometers thick and preferably consist of carbon.
  • the open-pore structure which is impregnated with transition metal / saturated aluminum, is supplied continuously from cavities arranged in the supporting body, into which the open-pore structure protrudes , or from another location on the open-pore structure at which solid aluminide can be held.
  • titanium alu inides are preferably used. Depending on the percentage of titanium, these aluminides have different physical states at the electrolysis temperature in the range of 900 to 1000 ° C:
  • Aluminides with less than 37.2 wt .-% titanium are viscous to pasty at electrolysis temperature. These can therefore not be used as solid shaped bodies, but rather only as bulk cathodes in cavities of the supporting body.
  • aluminides with a titanium content above 37.2 (up to 63)% by weight of titanium can also be associated as solid moldings with the open-pore structure.
  • the aluminum produced during the electrolysis process flows along the diagonally arranged open-pore structure and mixes with the impregnating aluminum saturated with transition metal / s and in this would gradually reduce the • transition metal content to such an extent that the open-pore structure would be attacked and gradually dissolved. This is prevented, however, by the open-pore structure being able to be fed continuously from aluminide stocks.
  • the transition metal extracted from the saturated aluminum is continuously replaced by new one, so that the open-pore structure remains impregnated with aluminum saturated with transition metal / s.
  • the open-pore structure in particular a 1-5 mm thick felt made of carbon fibers, is coated with a thin, well-adhering layer of titanium carbide or titanium diboride.
  • the layers which are preferably less than 0.4 ⁇ m thick, are produced, for example, by CVD (Chemical Vapor Deposition). If the aluminum impregnating the felt is permanently saturated with titanium, the wettable coating is not dissolved, as a result of which the life of the felt can be multiplied.
  • a felt consisting of coated carbon fibers has the further advantage that if the coating is defective, the entire work surface does not become unusable, but only individual fibers are dissolved prematurely.
  • the main advantage of the invention is thus that simple ceramic means can be used to replace expensive ceramic moldings by supporting bodies made of a cheap, easily moldable material with an open-pore surface structure impregnated with aluminum saturated with transition metal / s.
  • the solid-state cathodes according to the invention are also particularly suitable for converting existing aluminum melt flow electrolysis cells.
  • FIG. 1 shows a solid-state cathode with a conductive support body and a correspondingly designed anode
  • FIG. 2 shows a solid-state cathode with a support body made of electrically insulating material and anode designed accordingly
  • solid-state cathodes made of electrically conductive material and correspondingly designed anodes.
  • solid cathodes 10 and anode blocks 12 arranged in pairs form the electrode units of the electrolytic cell.
  • the solid cathode 10 consists of a shaped support body 14 made of carbon and a felt 16 attached to the work surface facing the anode body 12 made of carbon fibers coated with titanium carbide. Rags of this approximately 4 mm thick felt 16 extend into a cavity 18 in the carrier body 14, which is filled with a titanium, aluminide 19 dough at electrolysis temperature, which consists, for example, of 80% by weight aluminum and 20% by weight titanium.
  • the feet 20 of the support body 14 are in a correspondingly OMPI formed recesses in the carbon base 22 of the electrolytic cell.
  • the density of the solid-state cathode 10 must therefore be greater than that of the liquid aluminum 24.
  • the felt 16 is impregnated with aluminum saturated with titanium, which system forms the cathode.
  • the deposited aluminum mixes with the aluminum saturated with titanium in the felt and flows according to the inclination of the working surface of the solid-state cathode to the center of the electrode element.
  • the felt 16 acts like a wick in the oil, liquid alloy is drawn from the cavity 18 with the pasty titanium aluminide and thus the current losses are replaced. Without this replacement of the used titanium, the deposited aluminum would dissolve the titanium carbide coating on the carbon fibers and render the cathode surface non-wettable.
  • a solid-state cathode 10 and an anode block 12 form a pair of electrodes.
  • the supporting body 14 consists of an insulating material, for example of divegesinter ⁇ tem alumina, alumina-containing ceramics, silicon carbide or silicon carbide siliziumnitridjobem.
  • the felt 16 In order to ensure that the electrical direct current flows away, the felt 16 always extends along as far as possible all side surfaces of the support body 14 into the liquid aluminum 24. ''
  • the cavity 18 is trough-shaped, with relatively large opening is formed and filled with solid Titanaluminidgranalien, which for example consist of 55 wt .-% aluminum and 45 wt .-% titanium. In contrast, the felt 16 does not reach down into the cavity 18; The aluminum impregnating the felt 16 with titanium is saturated by the convection of the molten electrolyte 26.
  • the deposited aluminum flows through an opening 28 in the support body 14.
  • the apparent density of the entire solid cathode, at working temperature, must lie between the density of the molten electrolyte and the molten aluminum. In the case of support bodies 14 made of carbon, this is achieved by inserting iron pieces 30 into closed cavities, for example in the form of a ring.
  • solid cathodes 10 attached to a cathodic suspension system 36 and anode bodies 12 attached to an anodic suspension system 38 are alternatively arranged.
  • the felt 16 is fed by sleeves 34 which are placed over the support rods of the support bodies 14 and which consist of a solid aluminide.
  • the cathodes and anodes can be shifted to the right in the direction of the arrow.
  • a mechanism known per se ensures that the same interpolar distances exist between the anode and cathode after each shift.
  • anodes 12 and cathodes 14 arranged on the left have to be displaced more than those arranged on the right.
  • OMPI Burned-off anodes are removed together with the cathode on the right. A sufficiently large space has now been created on the left-hand side so that the cathode can be reinserted together with a new anode.

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)

Abstract

La cathode solide (10) est constituée essentiellement d'un corps porteur (14) et d'une structure poreuse (16) à pores ouverts, se trouvant au moins dans la zone de travail. La structure poreuse est imprégnée resp. imbibée d'aluminium saturé par au moins un métal de transition du groupe IV A, V A et VI A du système périodique des éléments. Cette structure (16) peut être alimentée de manière continue à partir de réserves de composés d'aluminium (19, 34). Un feutre d'une épaisseur de quelques millimètres, composé de fibres de carbone enduites, s'est révélé comme particulièrement adapté en tant que structure poreuse à pores ouverts. Les cathodes solides (10) sont peu coûteuses et peuvent être fabriquées en matériau malléable.
EP82902974A 1981-10-23 1982-10-14 Cathode de cellule d'electrolyse de masse en fusion pour la preparation d'aluminium Expired EP0091914B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82902974T ATE15079T1 (de) 1981-10-23 1982-10-14 Kathode fuer eine schmelzflusselektrolysezelle zur herstellung von aluminium.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH6788/81A CH648870A5 (de) 1981-10-23 1981-10-23 Kathode fuer eine schmelzflusselektrolysezelle zur herstellung von aluminium.
CH6788/81 1981-10-23

Publications (2)

Publication Number Publication Date
EP0091914A1 true EP0091914A1 (fr) 1983-10-26
EP0091914B1 EP0091914B1 (fr) 1985-08-21

Family

ID=4315036

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82902974A Expired EP0091914B1 (fr) 1981-10-23 1982-10-14 Cathode de cellule d'electrolyse de masse en fusion pour la preparation d'aluminium

Country Status (8)

Country Link
US (1) US4462886A (fr)
EP (1) EP0091914B1 (fr)
CA (1) CA1209526A (fr)
CH (1) CH648870A5 (fr)
DE (1) DE3142686C1 (fr)
IT (1) IT1152748B (fr)
NO (1) NO832198L (fr)
WO (1) WO1983001465A1 (fr)

Families Citing this family (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2518124A1 (fr) * 1981-12-11 1983-06-17 Pechiney Aluminium Elements cathodiques flottants, a base de refractaire electroconducteur, pour la production d'aluminium par electrolyse
EP0094353B1 (fr) * 1982-05-10 1988-01-20 Eltech Systems Corporation Matériaux mouillables par l'aluminium
US4560448A (en) * 1982-05-10 1985-12-24 Eltech Systems Corporation Aluminum wettable materials for aluminum production
US4544457A (en) * 1982-05-10 1985-10-01 Eltech Systems Corporation Dimensionally stable drained aluminum electrowinning cathode method and apparatus
EP0096001B1 (fr) * 1982-05-10 1987-01-14 Eltech Systems Corporation Cathode dimensionellement stable à drainage pour l'obtention électrolytique d'aluminium, méthode et appareil pour sa fabrication
FR2529580B1 (fr) * 1982-06-30 1986-03-21 Pechiney Aluminium Cuve d'electrolyse pour la production d'aluminium, comportant un ecran conducteur flottant
CH651855A5 (de) * 1982-07-09 1985-10-15 Alusuisse Festkoerperkathode in einer schmelzflusselektrolysezelle.
US4664760A (en) * 1983-04-26 1987-05-12 Aluminum Company Of America Electrolytic cell and method of electrolysis using supported electrodes
US4622111A (en) * 1983-04-26 1986-11-11 Aluminum Company Of America Apparatus and method for electrolysis and inclined electrodes
US4596637A (en) * 1983-04-26 1986-06-24 Aluminum Company Of America Apparatus and method for electrolysis and float
WO1992003597A1 (fr) * 1990-08-20 1992-03-05 Comalco Aluminium Limited Cellules de fusion d'aluminium ameliorees
DE4118304A1 (de) * 1991-06-04 1992-12-24 Vaw Ver Aluminium Werke Ag Elektrolysezelle zur aluminiumgewinnung
CA2108072A1 (fr) * 1992-03-19 1995-04-09 Robert P. Coe Protection des billets de spectacle contre la contrefacon
DE69526264T2 (de) * 1994-09-08 2002-10-24 Moltech Invent Sa Aluminium Elektrolysezelle mit drainierfähige Kathode
US5472578A (en) * 1994-09-16 1995-12-05 Moltech Invent S.A. Aluminium production cell and assembly
US5498320A (en) * 1994-12-15 1996-03-12 Solv-Ex Corporation Method and apparatus for electrolytic reduction of fine-particle alumina with porous-cathode cells
ES2238318T3 (es) * 1999-10-26 2005-09-01 Moltech Invent S.A. Celda para la extraccion electrolitica de aluminio con catodo drenado con mejor circulacion de electrolito.
ATE272728T1 (de) * 2001-03-07 2004-08-15 Moltech Invent Sa Zelle zur elektrogewinnung von aluminium operierend mit auf metall basierenden anoden
CN101698945B (zh) * 2009-11-03 2011-07-27 中国铝业股份有限公司 一种碳素纤维增强型阴极炭块及其制备方法
CN102953083B (zh) * 2011-08-25 2016-08-24 贵阳铝镁设计研究院有限公司 内腔阴极结构铝电解槽

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE549859A (fr) * 1955-07-28
US3459515A (en) * 1964-03-31 1969-08-05 Du Pont Cermets of aluminum with titanium carbide and titanium and zirconium borides
US3471380A (en) * 1966-10-25 1969-10-07 Reynolds Metals Co Method of treating cathode surfaces in alumina reduction cells
US3661736A (en) * 1969-05-07 1972-05-09 Olin Mathieson Refractory hard metal composite cathode aluminum reduction cell
US4224128A (en) * 1979-08-17 1980-09-23 Ppg Industries, Inc. Cathode assembly for electrolytic aluminum reduction cell
US4339316A (en) * 1980-09-22 1982-07-13 Aluminum Company Of America Intermediate layer for seating RHM tubes in cathode blocks

Non-Patent Citations (1)

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Title
See references of WO8301465A1 *

Also Published As

Publication number Publication date
DE3142686C1 (de) 1983-02-03
IT1152748B (it) 1987-01-07
NO832198L (no) 1983-06-17
CA1209526A (fr) 1986-08-12
WO1983001465A1 (fr) 1983-04-28
EP0091914B1 (fr) 1985-08-21
IT8223834A0 (it) 1982-10-20
US4462886A (en) 1984-07-31
CH648870A5 (de) 1985-04-15

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