EP1109952A1 - Anodes multicouches non carbonees a base de metal pour cellules de production d'aluminium - Google Patents

Anodes multicouches non carbonees a base de metal pour cellules de production d'aluminium

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Publication number
EP1109952A1
EP1109952A1 EP99931413A EP99931413A EP1109952A1 EP 1109952 A1 EP1109952 A1 EP 1109952A1 EP 99931413 A EP99931413 A EP 99931413A EP 99931413 A EP99931413 A EP 99931413A EP 1109952 A1 EP1109952 A1 EP 1109952A1
Authority
EP
European Patent Office
Prior art keywords
anode
layer
oxygen
nickel
active layer
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
EP99931413A
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German (de)
English (en)
Other versions
EP1109952B1 (fr
Inventor
Jean-Jacques Duruz
Vittorio De Nora
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.)
Moltech Invent SA
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Moltech Invent SA
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Filing date
Publication date
Priority claimed from US09/126,839 external-priority patent/US6372099B1/en
Priority claimed from US09/126,206 external-priority patent/US6077415A/en
Application filed by Moltech Invent SA filed Critical Moltech Invent SA
Publication of EP1109952A1 publication Critical patent/EP1109952A1/fr
Application granted granted Critical
Publication of EP1109952B1 publication Critical patent/EP1109952B1/fr
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Expired - Lifetime legal-status Critical Current

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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
    • 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
    • C25C3/12—Anodes

Definitions

  • This invention relates to multi-layer non-carbon, metal-based anodes, for use in cells for the electrowinning of aluminium by the electrolysis of alumina dissolved in a molten fluoride-containing electrolyte, and to methods for their fabrication and reconditioning, as well as to electrowinning cells containing such anodes and their use to produce aluminium.
  • the anodes are still made of carbonaceous material and must be replaced every few weeks .
  • the oxygen which should evolve on the anode surface combines with the carbon to form polluting CO2 and small amounts of CO and fluorine-containing dangerous gases.
  • the actual consumption of the anode is as much as 450 Kg/Ton of aluminium produced which is more than 1/3 higher than the theoretical amount of 333 Kg/Ton.
  • US Patent 4,614,569 (Duruz/Derivaz/Debely/ Adorian) describes anodes for aluminium electrowinning coated with a protective coating of cerium oxyfluoride, formed in-situ in the cell or pre-applied, this coating being maintained by the addition of cerium to the molten cryolite electrolyte. This made it possible to have a protection of the surface only from the electrolyte attack and to a certain extent from the gaseous oxygen but not from the nascent monoatomic oxygen.
  • EP Patent application 0 306 100 (Nyguen/Lazouni/
  • Doan describes anodes composed of a chromium, nickel, cobalt and/or iron based substrate covered with an oxygen barrier layer and a ceramic coating of nickel, copper and/or manganese oxide which may be further covered with an in-situ formed protective cerium oxyfluoride layer.
  • Metal or metal-based anodes are highly desirable in aluminium electrowinning cells instead of carbon-based anodes. As mentioned hereabove, many attempts were made to use metallic anodes for aluminium production, however they were never adopted by the aluminium industry.
  • An object of the invention is to provide a multilayer functionally graded coating for metal-based anodes for aluminium electrowinning cells which is substantially impervious to molecular oxygen and also to monoatomic oxygen and is electrochemically active for the oxidation reaction of oxygen ions present at the anode/electrolyte interface into monoatomic oxygen, as well as for subsequent reaction for the formation of biatomic molecular oxygen evolving as gas.
  • Another object of the invention is to provide a coating for metal-based anodes for aluminium electrowinning cells which has a high electrochemical activity, a long life and which can easily be applied onto a metal-based anode substrate.
  • a further object of the invention is to reduce substantially the consumption of the active anode surface of metal-based anodes for aluminium electrowinning cells which is attacked by the nascent oxygen produced by enhancing the reaction of nascent oxygen to gaseous oxygen which is much less active in oxidising metal anodes of aluminium electrowinning cells.
  • a major object of the invention is to provide an anode for aluminium electrowinning cells which has no carbon so as to eliminate carbon-generated pollution and eliminate the high carbon anode cost.
  • the invention relates to a composite, high- temperature resistant, non-carbon, metal-based, oxygen- evolving anode of a cell for the electrowinning of aluminium by the electrolysis of alumina dissolved in a molten fluoride-containing electrolyte.
  • the anode comprises a metal-based core structure of low electrical resistance, for connecting the anode to a positive current supply, coated with a series of superimposed, adherent, electrically conductive layers.
  • the conductive layers consist of:
  • an electrochemically active layer on the outermost intermediate layer for the oxidation reaction of oxygen ions present at the anode/electrolyte interface into nascent monoatomic oxygen, as well as for subsequent reaction for the formation of gaseous biatomic molecular oxygen evolving as gas, the active layer protecting the intermediate layer (s) against dissolution.
  • the active layer comprises at least one transition metal and/or an oxide thereof (excluding the lanthanides and actinides and their oxides alone) , for instance iron, cobalt, nickel, copper, chromium or titanium as metals and/or oxides.
  • the active layer may be slowly consumable during electrolysis .
  • metal-based anode means that the anode contains at least one metal in the anode core structure and/or in the protective layers as such or as alloys, intermetallics and/or cermets.
  • the core structure may comprise at least one metal selected from nickel, copper, cobalt, chromium, molybdenum, tantalum, niobium or iron.
  • the core structure may be made of an alloy consisting of 10 to 30 weight% of chromium, 55 to 90% of at least one of nickel, cobalt or iron, and 0 to 15% of aluminium, titanium, zirconium, yttrium, hafnium or niobium.
  • the core may be nickel plated copper.
  • the core structure may comprise an alloy or intermetallic compound containing at least two metals selected from nickel, cobalt, iron and aluminium.
  • the core structure can comprise a cermet containing copper and/or nickel as a metal, and a ceramic phase.
  • the oxygen barrier layer comprises at least one oxide selected from chromium, niobium and nickel oxide.
  • the oxygen barrier layer may be formed on the core structure by surface oxidation.
  • the oxygen barrier may optionally be formed by applying a precursor which is then converted into a functional barrier by heat treatment, such as applying a layer of chromium, niobium or nickel metal on the core which can then be oxidised.
  • One of the intermediate layers normally contains copper, or copper with at least one of nickel and cobalt, and/or oxide (s) thereof.
  • An intermediate layer may also comprise iron cuprate, nickel ferrite and/or cobalt ferrite.
  • one of the intermediate layers comprises an oxidised alloy containing 20 to 60 weight% of copper with one or more further metals forming a solid solution with copper, such metals being generally nickel and/or cobalt.
  • the electrochemically active layer comprises at least one oxide which may slowly wear away during electrolysis.
  • the electrochemically active layer comprises (an) oxide (s) throughout its thickness.
  • An oxide may be present in the electrochemically active layer as such, or in a multi-compound mixed oxide and/or in a solid solution of oxides.
  • the oxide may be in the form of a simple, double and/or multiple oxide, and/or in the form of a stoichiometric or non- stoichiometric oxide.
  • the electrochemically active layer may for instance comprise a metal, alloy, intermetallic compound or cermet which during normal operation in the cell is slowly consumable by oxidation of its surface and dissolution into the electrolyte of the formed surface oxide.
  • the rate of oxidation may be substantially equal to the rate of dissolution.
  • the electrochemically active layer containing metals is pre-oxidised prior to electrolysis.
  • the metals of the electrochemically active layer may be iron with at least one metal selected from nickel, copper, cobalt, aluminium and zinc.
  • the electrochemically active layer may further comprise at least one additive selected from beryllium, magnesium, yttrium, titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhodium, silver, hafnium, lithium, cerium and other Lanthanides .
  • the electrochemically active layer may also comprise at least one electrocatalyst for the anode reaction selected from iridium, palladium, platinum, rhodium, ruthenium, silicon, tin, mischmetal and metals of the Lanthanide series, and mixture, oxides and compounds thereof, for example as disclosed in W099/36592 (de Nora) .
  • the electrochemically active layer may be a surface oxidised iron-nickel layer, the surface containing iron oxide, nickel oxide or a mixture thereof.
  • the electrochemically active layer comprises spinels and/or perovskites .
  • the electrochemically active layer may comprise ferrites, such as ferrites selected from the group consisting of cobalt, copper, manganese, magnesium, nickel and zinc ferrite, and mixtures thereof, in particular nickel ferrite partially substituted with Fe 2+ .
  • the ferrite may be doped with at least one oxide selected from chromium, titanium, tin and zirconium oxide.
  • the electrochemically active layer can also comprise ceramic oxides containing combinations of divalent nickel, cobalt, magnesium, manganese, copper and zinc with divalent/trivalent nickel, cobalt, manganese and/or iron.
  • the electrochemically active layer may for instance have doped, non-stoichiometric and/or partially substituted spinels, the doped spinels comprising dopants selected from Ti 4+ , Zr 4+ , Sn + , Fe 4+ , Hf + , Mn + , Fe 3+ , Ni 3+ , Co 3+ , Mn 3+ , Al 3+ , Cr 3+ , Fe 2+ , Ni 2+ , Co 2+ , Mg 2+ , Mn 2+ , Cu 2+ , Zn 2+ and Li + .
  • the electrochemically active layer may be made of an oxidised nickel-cobalt alloy.
  • an alloy forms upon oxidation complex oxides, in particular (Ni x Co 1 _ x )0, having semi-conducting properties.
  • nickel-cobalt oxides provide an advantage over conventional nickel ferrite. Whereas trivalent iron ions of nickel ferrite are slowly replaced by trivalent aluminium ions in the octahedral sites of the spinel lattice, which leads to a loss of conductivity and of mechanical stability, nickel-cobalt alloys oxidised in oxygen at 1000°C lead to a semi-conducting mixed oxide structure of NiCo 2 0 4 and Co 3 0 4 spinels which is similar to the NaCl lattice. In these spinels, a replacement of trivalent cobalt ions by trivalent aluminium ions is unlikely.
  • the cobalt nickel atomic ratio is preferably chosen in the range 2 to 2.7.
  • HSLA high-strength low-alloy
  • HSLA steels are known for their strength and resistance to atmospheric corrosion especially at lower temperatures (below 0°C) in different areas of technology such as civil engineering (bridges, dock walls, sea walls, piping), architecture (buildings, frames) and mechanical engineering (welded/bolted/riveted structures, car and railway industry, high pressure vessels) .
  • civil engineering bridges, dock walls, sea walls, piping
  • architecture buildings, frames
  • mechanical engineering welded/bolted/riveted structures, car and railway industry, high pressure vessels
  • the iron oxide-based surface layer formed on the surface of a HSLA steel under oxidising conditions limits also at elevated temperatures the diffusion of oxygen oxidising the surface of the HSLA steel.
  • diffusion of oxygen through the surface layer decreases with an increasing thickness thereof.
  • the rate of formation of the iron oxide-based surface layer (by oxidation of the surface of the HSLA steel) reaches the rate of dissolution or delamination of the surface layer after a transitional period during which the surface layer grows or decreases to reach an equilibrium thickness in the specific environment.
  • High-strength low-alloy (HSLA) steels are a group of low-carbon steels (typically up to 0.5 weight% carbon of the total) that contain small amounts of alloying elements. These steels have better mechanical properties and sometimes better corrosion resistance than carbon steels.
  • the surface of a high-strength low-alloy steel electrochemically active layer may be oxidised in an electrolytic cell or in an oxidising atmosphere, in particular a relatively pure oxygen atmosphere.
  • the surface of the high-strength low-alloy steel layer may be oxidised in a first electrolytic cell and then transferred to an aluminium production cell.
  • oxidation would typically last 5 to 15 hours at 800 to 1000°C.
  • the oxidation treatment may take place in air or in oxygen for 5 to 25 hours at 750 to 1150°C.
  • a high-strength low-alloy steel layer may be tempered or annealed after pre-oxidation.
  • the high-strength low-alloy steel layer may be maintained at elevated temperature after pre- oxidation until immersion into the molten electrolyte of an aluminium production cell.
  • the high-strength low-alloy steel layer may comprise 94 to 98 weight% iron and carbon, the remaining constituents being one or more further metals selected from chromium, copper, nickel, silicon, titanium, tantalum, tungsten, vanadium, zirconium, aluminium, molybdenum, manganese and niobium, and optionally a small amount of at least one additive selected from boron, sulfur, phosphorus and nitrogen.
  • the electrochemically active layer is initially sufficiently thick to constitute an impermeable barrier to gaseous oxygen penetration, and even to nascent, mono-atomic oxygen.
  • any of these layers may be slurry applied, for instance by applying a precursor slurry.
  • the layers may also be applied in the form a precursor powder followed by heat-treating.
  • Several techniques may be used to apply the layers, such as dipping, spraying, painting, brushing, arc spraying, plasma spraying, electro-chemical deposition, physical vapour deposition, chemical vapour deposition or calendar rolling.
  • the invention also relates to a method of manufacturing an anode as described above.
  • the method comprises the steps of formation of the oxygen barrier layer(s), of the intermediate layer(s) and of the electrochemically active layer. It is possible to form the oxygen barrier by substrate oxidation after the intermediate barrier has been applied onto the substrate.
  • the method for manufacturing such an anode may also be used for reconditioning an anode whose electrochemically active layer is worn or damaged.
  • the method comprises clearing at least worn and/or damaged parts of the active surface from the core structure or from the outermost intermediate layer to which it adheres and then reconstituting at least the electrochemically active layer.
  • Another aspect of the invention is a cell for the production of aluminium by the electrolysis of alumina dissolved in a molten fluoride-containing electrolyte comprising at least one composite anode as described above .
  • the cell may comprise at least one aluminium-wettable cathode which can be a drained cathode on which aluminium is produced and from which it continuously drains.
  • Bipolar cells may comprise the anodes as described above as the anodic side of at least one bipolar electrode and/or as a terminal anode.
  • an electric current is passed from the surface of the terminal cathode to the surface of the terminal anode as ionic current in the electrolyte and as electronic current through the bipolar electrodes, thereby electrolysing the alumina dissolved in the electrolyte to produce aluminium on each cathode surface and oxygen on each anode surface.
  • the cell comprises means to improve the circulation of the electrolyte between the anodes and facing cathodes and/or means to facilitate dissolution of alumina in the electrolyte.
  • means to improve the circulation of the electrolyte between the anodes and facing cathodes and/or means to facilitate dissolution of alumina in the electrolyte can for instance be provided by the geometry of the cell as described in co-pending application PCT/IB99/00222 (de Nora/Duruz) or by periodically moving the anodes as described in co- pending application PCT/IB99/00223 (Duruz/Bell ⁇ ) .
  • the cell may be operated with the electrolyte at conventional temperatures, such as 950 to 970°C, or at reduced temperatures as low as 700°C.
  • Yet another aspect of the invention is a method of producing aluminium in such an aluminium electrowinning cell, wherein alumina is dissolved in the molten fluoride-containing electrolyte and then electrolysed to produce aluminium.
  • the active layer of the anode may be protected by an electrolyte- generated oxyfluoride-containing layer, such as cerium oxyfluoride self-formed on the electrochemically active layer as described in US Patent 4,614,569 (Duruz/Derivaz/ Debely/Adorian) .
  • an electrolyte- generated oxyfluoride-containing layer such as cerium oxyfluoride self-formed on the electrochemically active layer as described in US Patent 4,614,569 (Duruz/Derivaz/ Debely/Adorian) .
  • a test anode was made by coating by electro- deposition a core structure in the shape of a rod having a diameter of 12 mm consisting of 74 weight% nickel, 17 weight% chromium and 9 weight% iron, such as Inconel®, first with a nickel layer about 200 micron thick and then a copper layer about 100 micron thick.
  • the coated structure was heat treated at 1000°C in argon for 5 hours . This heat treatment provides for the interdiffusion of nickel and copper to form an intermediate layer.
  • the structure was then heat treated for 24 hours at 1000°C in air to form a chromium oxide (Cr 2 0 3 ) barrier layer on the core structure and oxidising at least partly the interdiffused nickel-copper layer thereby completing formation of the intermediate layer.
  • a nickel-ferrite powder was made by drying and calcining at 900°C the gel product obtained from an inorganic polymer precursor solution consisting of a mixture of molten Fe(N0 3 ) 3 .9 H 2 0 with a stoichiometric amount of Ni(C0 3 ) 2 .6 H 2 0.
  • a thick paste was made by mixing 1 g of this nickel-ferrite powder with 0.85 g of a nickel aluminate polymer solution containing the equivalent of 0.15 g of nickel oxide. This thick paste was then diluted with 1 ml of water and ground in a pestle and mortar to obtain a suitable viscosity to form a nickel-based paint.
  • An electrochemically active oxide layer was obtained on the core structure by applying the nickel- based paint onto the core structure with a brush.
  • the painted structure was allowed to dry for 30 minutes before heat treating it at 500°C for 1 hour to decompose volatile components and to consolidate the oxide coating.
  • the heat treated coating layer was about 15 micron thick. Further coating layers were applied following the same procedure in order to obtain a 200 micron thick electrochemically active coating covering the intermediate layer and barrier layer on the core structure.
  • the anode was then tested in a cryolite melt containing approximately 6 weight% alumina at 970°C by passing a current at a current density of about 0.8 A/cm 2 . After 100 hours the anode was extracted from the cryolite and showed no significant internal corrosion after microscopic examination of a cross-section of the anode sample .
  • the Example can be repeated with an electrochemically active layer obtained from a feed prepared by slurrying nickel ferrite powder in an inorganic polymer solution having the required composition for the formation of NiFe 2 0 4 .
  • the powder to polymer ratio was 1 to 0.25.
  • Several layers of the coating feed can be brushed onto the nickel-copper layer and heat treated to form the electrochemically active layer on the intermediate layer.
  • Example can be repeated with an electrochemically active layer obtained from an amount of 1 g of commercially available nickel ferrite powder slurried with 1 g of an inorganic polymer consisting of a precursor of 0.25 g equivalent nickel-ferrite per 1 ml.
  • An amount corresponding to 5 weight% of Ir0 2 acting as an electrocatalyst for the rapid conversion of oxygen ions into monoatomic oxygen and subsequently gaseous oxygen can be added to the slurry as IrCl 4 , as described in
  • the slurry can be brush-coated onto the interdiffused and at least partly oxidised nickel copper alloy layer by applying 3 successive 50 micron thick layers of the slurry, each slurry-applied layer should be allowed to dry by heat-treating the anode at 500°C for 15 minutes between each layer application.
  • a nickel metal core structure was heated in air at 1100°C for 16 hours to form an oxidised surface layer having a thickness of about 35 micron.
  • the surface layer was black showing the presence of nickel oxide (Ni0 1+x ) which is known to act as an oxygen barrier layer and to be electrically conductive.
  • a mixture of nickel-ferrite and copper-ferrite powder was slurried in an inorganic polymer solution having the required composition for the formation of CuFe 2 0 4 and NiFe 2 0 4 .
  • the polymer solution had a concentration of 350g/l oxide equivalent and the powder to polymer ratio was 1 to 0.25.
  • the slurry was used as a coating feed and brushed onto the nickel oxide surface layer of the core structure to form a ferrite-based electrochemically active layer on the nickel oxide layer. After drying the ferrite-based layer at 105°C, the core structure was submitted to a heat treatment at 500°C in air to consolidate the coating.
  • a steel core structure was coated with a slurry prepared by suspending chromium oxide (Cr 2 0 3 ) in an inorganic Cr 3+ polymer solution.
  • the feed concentration was greater than 500 g/1 of Cr 2 0 3 .
  • Example 2 After heat-treating to consolidate the chromium oxide (Cr 2 0 3 ) applied layer, thereby forming a barrier layer on the steel structure, a second intermediate layer of interdiffused nickel-copper was applied as described in Example 1 on the barrier layer. Finally the intermediate layer was coated with several electrochemically active layers of CuFe 2 0 4 and NiFe 2 0 4 as described in Example 2.
  • a test anode was obtained by coating an Inconel® metal core structure with a nickel copper alloy layer and heat-treating it as described in Example 1 to form a barrier layer and an intermediate layer on the metal core structure.
  • a further layer of a nickel-iron based alloy consisting of 79 weight% nickel, 10 weight% iron and 11 weight% copper of a thickness of approximately 1 mm was then applied on the interdiffused and at least partly oxidised nickel copper layer by plasma spraying.
  • This alloy layer was then pre-oxidised at 1100°C for 5 hours for the formation of an electrochemically active oxide layer on the alloy layer.
  • pre-oxidation of the alloy layer is preferred, the treatment is not necessary before using the anode in the cell to produce aluminium.
  • the test anode was then tested in a cell as described in Example 1. During electrolysis the alloy layer was further oxidised at the alloy layer/active layer interface, self-forming the electrochemically active layer. Simultaneously, the active layer was slowly dissolved into the electrolyte at the active layer/electrolyte interface at substantially the same rate as its rate of formation at the alloy layer/active layer interface, thereby maintaining the thickness of the oxide layer substantially constant, as the alloy layer wears away.
  • the anode When the alloy layer is worn or damaged, the anode can be reconditioned by clearing at least the worn or damaged parts and reconstituting at least the alloy layer .
  • the Example can be repeated by applying on the interdiffused nickel copper intermediate layer a nickel- iron alloy consisting of 30 weight% nickel and 70 weight% iron having a thickness of about 0.5 mm by arc spraying or plasma spraying.
  • the nickel-iron alloy layer can be pre-oxidised in air at 1100°C for 6 hours to form a dense iron oxide-based electrochemically active outer surface layer on the intermediate layer.
  • a test anode was obtained by electrodepositing onto a copper metal core structure a series of successive metallic layers consisting of a nickel layer (10 micron thick) which is known to be well adherent to copper and chromium, a chromium layer (25 micron thick) , a nickel layer (50 micron thick) and a copper layer (50 micron thick) and heat treating first in argon and then in oxygen as described in Example 1 to interdiffuse and oxidise the nickel and the copper layers to form an intermediate layer, and oxidise the chromium layer to form an oxygen barrier layer.
  • An iron layer (200 micron thick) was then electrodeposited onto the interdiffused nickel-copper layer and pre-oxidised at 1100°C in air for 6 hours to form a dense iron oxide-based electrochemically active outer surface layer on the intermediate layer.
  • the anode was then tested in molten electrolyte containing approximately 6 weight% alumina at 850°C at a current density of about 0.8 A/cm 2 .
  • the anode was extracted from the cryolite after 100 hours and showed no sign of significant internal or external corrosion after microscopic examination of a cross-section of the anode sample.
  • Examples 1 to 5 have been repeated by replacing the electrochemically active layer by a Cor-TenTM type low-carbon high-strength (HSLA) steel layer doped with niobium, titanium, chromium and copper in a total amount of less than 4 weight% which is also electrochemically active upon oxidation.
  • the anodes were pre-oxidised in air at about 1050°C for 15 hours for the formation of a dense hematite-based outer layer constituting an oxide- based surface layer on an un-oxidised anode body. The anodes were then tested in a fluoride- containing molten electrolyte at 850°C containing cryolite and 25 weight% excess of AlF 3 and approximately
  • alumina feed contained sufficient iron oxide to slow down the dissolution of the hematite-based electrochemically active anode layer.
  • the produced aluminium was also analysed and showed an iron contamination of about 700 ppm which is below the tolerated iron contamination in commercial aluminium production.
  • the Example can be repeated with different HSLA steel layers such as an HSLA steel layer doped with manganese 0.4 weight%, niobium 0.02 weight%, molybdenum 0.02 weight%, copper 0.3 weight%, nickel 0.45 weight% and chromium 0.8 weight%, or an HSLA steel layer doped with nickel, copper and silicon in a total amount of less than 1.5 weight% .
  • HSLA steel layers such as an HSLA steel layer doped with manganese 0.4 weight%, niobium 0.02 weight%, molybdenum 0.02 weight%, copper 0.3 weight%, nickel 0.45 weight% and chromium 0.8 weight%, or an HSLA steel layer doped with nickel, copper and silicon in a total amount of less than 1.5 weight% .

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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)
  • Other Surface Treatments For Metallic Materials (AREA)

Abstract

L'invention concerne une anode composite non carbonée à base de métal résistante à haute température, pour une cellule d'extraction électrolytique de l'aluminium. Cette anode comprend une structure centrale d'une faible résistance électrique à base de métal, permettant de raccorder ladite anode à une source de courant positif, cette structure étant revêtue d'une série de couches superposées, adhésives, et électriquement conductrices. Ces couches renferment : au moins une couche située sur ladite structure centrale, de manière à former une protection sensiblement imperméable à l'oxygène monoatomique et à l'oxygène moléculaire; une ou plusieurs couches protectrices intermédiaires situées sur cette(ces) couche(s) d'arrêt, ces couches protectrices restant inactives pendant les réactions destinées à faire évoluer le gaz oxygène; et une couche active d'un point de vue électrochimique, permettant une réaction d'oxydation des ions oxygène présents au niveau de l'interface anode/électrolyte pour transformer ceux-ci en oxygène monoatomique à l'état naissant, une réaction ultérieure étant par ailleurs destinée à former de l'oxygène biatomique gazeux. La couche active renferme au moins un métal de transition et/ou un oxyde de celui-ci (à l'exception des lanthanides et des actinides et de leurs oxydes).
EP19990931413 1998-07-30 1999-07-30 Anodes multicouches non carbonees a base de metal pour cellules de production d'aluminium Expired - Lifetime EP1109952B1 (fr)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
US126206 1998-07-30
US09/126,839 US6372099B1 (en) 1998-07-30 1998-07-30 Cells for the electrowinning of aluminium having dimensionally stable metal-based anodes
US09/126,206 US6077415A (en) 1998-07-30 1998-07-30 Multi-layer non-carbon metal-based anodes for aluminum production cells and method
US126839 1998-07-30
WOPCT/IB99/00015 1999-01-08
IB9900015 1999-01-08
PCT/IB1999/001357 WO2000006800A1 (fr) 1998-07-30 1999-07-30 Anodes multicouches non carbonees a base de metal pour cellules de production d'aluminium

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EP1109952A1 true EP1109952A1 (fr) 2001-06-27
EP1109952B1 EP1109952B1 (fr) 2004-10-27

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AU (1) AU4794599A (fr)
DE (1) DE69921491T2 (fr)
ES (1) ES2229728T3 (fr)
WO (1) WO2000006800A1 (fr)

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JP2018517061A (ja) * 2015-05-26 2018-06-28 Tdk株式会社 複合体および電解用電極
CN111151279B (zh) * 2019-12-27 2021-01-29 宁波工程学院 一种N,P掺杂碳纤维负载FeCo/Co2 P的复合催化剂及其制备方法

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WO1989001992A1 (fr) * 1987-09-02 1989-03-09 Moltech Invent S.A. Matiere composite en ceramique et metal
EP1049816A1 (fr) * 1998-01-20 2000-11-08 MOLTECH Invent S.A. Anodes metalliques exemptes de carbone a activite electrocatalytique pour des cellules electrolytiques de production d'aluminium

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0006800A1 *

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AU4794599A (en) 2000-02-21
DE69921491D1 (de) 2004-12-02
ES2229728T3 (es) 2005-04-16
DE69921491T2 (de) 2005-10-27
WO2000006800A1 (fr) 2000-02-10
EP1109952B1 (fr) 2004-10-27

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