Abstract: Compositions for making wettable cathodes to be used in aluminum electrolysis cells are disclosed. The compositions generally include titanium diboride (TiB2) and metal additives. The amount of selected metal additives may result in production of electrodes having a tailored density and/or porosity. The electrodes may be durable and used in aluminum electrolysis cells.

Abstract: A metallic oxygen evolving anode for electrowinning aluminum by decomposition of alumina dissolved in a cryolite-based molten electrolyte, and operable at anode current densities of 1.1 to 1.3 A/cm2, comprises an alloy of nickel, iron, manganese, optionally copper, and silicon. Preferably, the alloy is composed of 64-66 w % Ni; Iron; 25-27 w % Fe; 7-9 w % Mn; 0-0.7 w % Cu; and 0.4-0.6 w % Si. The weight ratio Ni/Fe is in the range 2.1 to 2.89, preferably 2.3 to 2.6, the weight ratio Ni/(Ni+Cu) is greater than 0.98, the weight ratio Cu/Ni is less than 0.01, and the weight ratio Mn/Ni is from 0.09 to 0.15. The alloy surface can comprise nickel ferrite produced by pre-oxidation of the alloy. The alloy, optionally with a pre-oxidized surface, can be coated with an external coating comprising cobalt oxide CoO.

Abstract: Method for manufacturing anodes used for the production of aluminium by fused bath electrolysis, said anodes comprising an anode stem made of a conducting metal and at least one block made of carbonaceous material called an anode block, said method including at least the following steps: a) obtain an anode stem; b) obtain a new anode block; c) fix one end of the anode stem onto the anode block, so as to give good mechanical attachment and good electrical connection between said stem and said anode block; said method being characterised in that before, during or after step c), but before placement of said anode in the electrolytic cell, a protective layer with a controlled thickness, typically between 5 and 25 cm composed of a material resistant to temperature and corrosion by the medium above the electrolytic bath is at least partially deposited on the upper surface of said anode block.

Abstract: A method of producing aluminium in a Hall-Héroult cell with prebaked anodes, as well as anodes for the same. The anodes are provided with slots in a wear (bottom) surface thereof for gas drainage. The slots are 2-8 millimeters wide, and preferably 3 millimeters.

Abstract: The subject invention pertains to methods for processing a solid material (M1X) comprising a solid solution of a non-metal species (X) in a metal or semi-metal (M1) or a compound between the non-metal species and the metal or semi-metal is immersed in a molten salt (M2Y). A cathodic potential is applied to the material to remove a portion of the non-metal species by electro-deoxidation. To remove the non-metal species at lower concentrations, a source of a reactive metal (M3) is immersed in the molten salt and is electronically connected to the material. Reactions occur at the material, where the non-metal species dissolves in the salt, and at the reactive metal, which reacts with the non-metal species dissolved in the salt to form a reaction product more stable than a compound between the non-metal species and the metal or semi-metal (M1). The non-metal species is thus removed from the solid material.

Abstract: An anode for electrowinning of aluminium from alumina comprises a cobalt-containing metallic outer part that is covered with an integral oxide layer containing predominantly cobalt oxide CoO. The integral oxide layer can be formed by surface oxidation of cobalt from the metallic outer part before use.

Abstract: A cell for electrowinning a metal, in particular aluminium, from a compound thereof dissolved in an electrolyte (30) comprises an anode (40) and a cathode (10,11) that contact the electrolyte (30), the cathode (10,11) being during use at a cathodic potential for reducing thereon species of the metal to be produced from the dissolved compound. The electrolyte (30) further contains species of at least one element that is liable to contaminate the product metal (20) and that has a cathodic reduction potential which is less negative than the cathodic potential of the metal to be produced. The cell further comprises a collector (50) for removing species of such element (s) from the electrolyte (30).

Abstract: An anode for electrowinning aluminium comprises an electrically conductive substrate that is covered with an applied electrochemically active coating comprising a layer that contains predominantly cobalt oxide CoO. The CoO layer can be connected to the substrate through an oxygen barrier layer, in particular containing copper, nickel, tungsten, molybdenum, tantalum and/or niobium.

Abstract: A cell for electrowinning aluminium from alumina, comprises: a metal-based anode having an electrochemically active outer part comprising a layer that contains predominantly cobalt oxide CoO; and a fluoride-containing molten electrolyte in which the active anode surface is immersed. The electrolyte is at a temperature below 950° C., in particular in the range from 910° to 940° C. The electrolyte consists of: 6.5 to 11 weight. % dissolved alumina; 35 to 44 weight % aluminium fluoride; 38 to 46 weight % sodium fluoride; 2 to 15 weight % potassium fluoride; 0 to 5 weight % calcium fluoride; and 0 to 5 weight % in total of one or more further constituents.

Abstract: Stable anodes comprising iron oxide useful for the electrolytic production of metal such as aluminum are disclosed. The iron oxide may comprise Fe3O4, Fe2O3, FeO or a combination thereof. During the electrolytic aluminum production process, the anodes remain stable at a controlled bath temperature of the aluminum production cell and current density through the anodes is controlled. The iron oxide-containing anodes may be used to produce commercial purity aluminum.

Abstract: A method for electrolytic production of aluminium metal from an electrolytic (3) including aluminium oxide, by performing electrolysis, with at least one inert anode (1) and at least one cathode (2) thus forming part of an electorwinning cell. The anode evolves oxygen gas and the cathode has aluminium discharged onto it in the electrolysis process, where the oxygen gas enforces an electrolyte flow pattern. The oxygen gas is directed to flow into anode grooves and is drained away from the interpolar room, thereby establishing an electrolyte flow pattern between the electrodes (1) and (2) and between over the anodes (1). The invention also concerns and anode assembly and an electrowinning cell.

Abstract: The purpose of the invention is a process for making a solid part designed to form all or part of an anode for the production of aluminium by fused bath electrolysis, containing a cermet formed from at least one metallic oxide such as a mixed oxide with spinel structure, and at least one metallic phase, in which a mixed oxide is used containing a metal R in the form of a cation in its chemical structure, the said metal R being fully or partly reducible by a reduction operation during the manufacturing process, so as to form all or part of the said metallic phase. This process can provide a cermet with a uniform distribution of fine metallic particles.

Abstract: A method of protecting an inert anode assembly (16) operating in an electrolysis cell (10) for producing metal when an adjacent assembly (16?) is removed exposing remaining assemblies to low ambient temperatures (40) by utilizing heat radiation shields (24) which can circumscribe every inert anode assembly (16), where the shields (24) remain intact and in place in the cell (10) while operating in molten electrolyte (15) at about 850° C.

Abstract: A method of forming a dense and crack-free hematite-containing protective layer on a metal-based substrate for use in a high temperature oxidising and/or corrosive environment comprises applying onto the substrate a particle mixture consisting of: 60 to 99 95 weight %, in particular 70 to 95 weight % such as 75 to 85 weight %, of hematite with or without iron metal and/or ferrous oxide; 1 to 25 weight %, in particular 5 8 to 20 weight % such as 8 to 15 weight %, of nitride and/or carbide particles, such as boron nitride, aluminium nitride or zirconium carbide particles; and 0 to 15 weight %, in particular 5 to 15 weight %, of one or more further constituents that consist of at least one metal or metal oxide or a heat-convertible precursor thereof.

Abstract: A method of manufacturing a component, in particular an aluminium electrowinning anode, for use at elevated temperature in an oxidising and/or corrosive environment comprises: applying onto a metal-based substrate layers of a particle mixture containing iron oxide particles and particles of a reactant-oxide selected from titanium, yttrium, ytterbium and tantalum oxides; and heat treating the applied layers to consolidate by reactive sintering of the iron oxide particles and the reactant-oxide particles to turn the applied layer into a protective coating made of a substantially continuous reacted oxide matrix of one or more multiple oxides of iron and the metal from the reactant-oxide. The metal-based substrate comprises at its surface during the heat treatment an integral anchorage-oxide of at least one metal of the substrate.

Abstract: Stable anodes comprising iron oxide useful for the electrolytic production of metal such as aluminum are disclosed. The iron oxide may comprise Fe3O4, Fe2O3, FeO or a combination thereof. During the electrolytic aluminum production process, the anodes remain stable at a controlled bath temperature of the aluminum production cell and current density through the anodes is controlled. The iron oxide-containing anodes may be used to produce commercial purity aluminum.

Abstract: An anode of a cell for the electrowinning of aluminium comprises a nickel-iron alloy substrate having a nickel metal rich outer portion with an electrolyte pervious integral nickel-iron oxide containing surface layer which adheres to the nickel metal rich outer portion of the nickel-iron alloy and which in use is electrochemically active for the evolution of oxygen. The oxide surface layer has a thickness such that, during use, the voltage drop therethrough is below the potential of dissolution of nickel-iron oxide. The nickel metal rich outer portion may contain cavities some or all of which, after oxidation, are partly or completely filled with iron oxides to form iron oxide containing inclusions.

Abstract: A cell for the electrowinning of aluminium comprising one or more anodes (10), each having a metal-based anode substrate, for instance comprising a metal core (11) covered with an metal layer 12, an oxygen barrier layer (13), one or more intermediate layers (14; 14A, 14B) and an iron layer (15). The anode substrate is covered with an electrochemically active transition metal oxide layer, in particular an iron oxide-based outside layer (16) such as a hematite-based layer, which remains dimensionally stable during operation in a cell by maintaining in the electrolyte a sufficient concentration of iron species and dissolved alumina. The cell operating temperature is sufficiently low so that the required concentration of iron species in the electrolyte (5) is limited by the reduced solubility of iron species in the electrolyte at the operating temperature, which consequently limits the contamination of the product aluminium by iron to an acceptable level.

Abstract: An anode of a cell for the electrowinning of aluminium comprises a nickel-iron alloy substrate having an openly porous nickel metal rich outer portion whose surface is electrochemically active. The outer portion is optionally covered with an external integral nickel-iron oxide containing surface layer which adheres to the nickel metal rich outer portion of the nickel-iron alloy and which in use is pervious to molten electrolyte. During use, the nickel metal rich outer portion contains cavities some or all of which are partly or completely filled with iron and nickel compounds, in particular oxides, fluorides and oxyfluorides.

Abstract: Electrolysis of alumina dissolved in a molten salt electrolyte employing inert anode and cathodes, the anode having a box shape with slots for the cathodes.

Abstract: An electrolytic cell for producing aluminum from alumina having a reservoir for collecting molten aluminum remote from the electrolysis.

Abstract: A material suitable for use as the active anode surface in the electrolytic reduction of alumina to aluminium metal defined by the formula: A1+xB1+&dgr;CdO4 where A is a divalent cation or a mixture of cations with a relative preference for octahedral coordination, B is a trivalent cation or mixture of cations with a relative preference for tetrahedral coordination, C is a trivalent cations with a relative preference for octahedral coordination or a four-valent cation with a relative preference for octahedral coordination, O is the element oxygen: When C is trivalent x=0, 0.8<d<1, &dgr;<0.2 and x+d+d is essentially equal to 1. When C is four-valent 0.4<x<0.6, 0.4<d<0.6, &dgr;<0.2 and x+d+&dgr; is essentially equal to 1.

Abstract: Ceramic inert anodes useful for the electrolytic production of aluminum are disclosed. The inert anodes comprise oxides of Ni, Fe and Al. The Ni—Fe—Al oxide inert anode materials have sufficient electrical conductivity at operation temperatures of aluminum production cells, and also possess good mechanical stability. The Ni—Fe—Al oxide inert anodes may be used to produce commercial purity aluminum.

Abstract: A cell of advanced design for the production of aluminium by the electrolysis of an aluminium compound dissolved in a molten electrolyte, has a cathode (30) of drained configuration, and at least one non-carbon anode (10) facing the cathode both covered by the electrolyte (54). The upper part of the cell contains a removable thermic insulating cover (60) placed just above the level of the electrolyte (54). Preferably, the cathode (30) comprises a cathode mass (32) supported by a cathode carrier (31) made of electrically conductive material which serves also for the uniform distribution of electric current to the cathode mass (32) from current feeders (42) which connect the cathode carrier (31) to the negative busbars.

Abstract: A method of inhibiting dissolution of a transition metal alloy anode (40) of an aluminium electrowinning cell comprises providing a sodium-inert layer (11,20,50,50′) on a sodium-active cathodic cell material (15), such as carbon, and electrolysing alumina dissolved in a sodium ion-containing molten electrolyte (30). Aluminium ions rather than sodium ions are cathodically reduced on the sodium-inert layer to inhibit the presence in the molten electrolyte (30) of soluble cathodically-produced sodium metal that constitutes an agent for chemically reducing the anode's transition metal oxides and anodically evolved oxygen, thereby inhibiting reduction of the anode's transition metal oxides by sodium metal and maintaining the evolved oxygen at the anode at a concentration such as to produce at the alloy/oxide layer interface stable and coherent transition metal oxides having a high level of oxidation.

Abstract: A method of preparing carbonaceous blocks or bodies for use in a cathode in an electrolytic cell for producing aluminum wherein the cell contains an electrolyte and has molten aluminum contacting the cathode, the cathode having improved wettability with molten aluminum. The method comprises the steps of providing a carbonaceous block and a boron oxide containing melt. The carbonaceous block is immersed in the melt and pressure is applied to the melt to impregnate the melt into pores in the block. Thereafter, the carbonaceous block is withdrawn from the melt, the block having boron oxide containing melt intruded into pores therein, the boron oxide capable of reacting with a source of titanium or zirconium or like metal to form titanium or zirconium diboride during heatup or operation of said cell.

Abstract: A solid cryolite/alumina mixture is used as the anode in an electrolytic aluminum winning process. The mixture may be used in the form of a crust formed on the electrolytic cell.

Abstract: A method of manufacturing an anode for use in a cell for the electrowinning of aluminium comprises oxidising before cell operation an iron-nickel alloy substrate in an oxygen-containing atmosphere, such as air, at a temperature which is at least 50° C., preferably 100° C., above the operating temperature of the cell to form on the surface of the iron-nickel substrate a coherent and adherent iron oxide-containing outer layer, in particular a hematite-containing layer having a limited ionic conductivity for oxygen ions and acting as a partial barrier to monoatomic oxygen. The outer layer is electrochemically active for the oxidation of oxygen ions and reduces also diffusion of oxygen to the iron-nickel alloy substrate when the anode is in use.

Abstract: A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising the steps of providing a molten salt electrolyte at a temperature of less than 900° C. having alumina dissolved therein in an electrolytic cell having a liner for containing the electrolyte, the liner having a bottom and walls extending upwardly from said bottom. A plurality of non-consumable anodes and cathodes are disposed in a vertical direction in the electrolyte, the cathodes having a plate configuration and the anodes having a flat configuration to compliment the cathodes. The anodes contain apertures therethrough to permit flow of electrolyte through the apertures to provide alumina-enriched electrolyte between the anodes and the cathodes. Electrical current is passed through the anodes and through the electrolyte to the cathodes, depositing aluminum at the cathodes and producing gas at the anodes.

Abstract: A cell for the electrowinning of aluminium comprising one or more anodes (10), each having a metal-based anode substrate, for instance comprising a metal core (11) covered with an metal layer 12, an oxygen barrier layer (13), one or more intermediate layers (14; 14A, 14B) and an iron layer (15). The anode substrate is covered with an electrochemically active transition metal oxide layer, in particular an iron oxide-based outside layer (16) such as a hematite-based layer, which remains dimensionally stable during operation in a cell by maintaining in the electrolyte a sufficient concentration of iron species and dissolved alumina. The cell operating temperature is sufficiently low so that the required concentration of iron species in the electrolyte (5) is limited by the reduced solubility of iron species in the electrolyte at the operating temperature, which consequently limits the contamination of the product aluminium by iron to an acceptable level.

Abstract: An improved method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising the steps of providing a molten salt electrolyte at a temperature less than 900° C. having alumina dissolved therein in an electrolytic cell having a liner for containing the electrolyte, the liner having a bottom and walls extending upwardly from the bottom, the liner being substantially inert with respect to the molten electrolyte. A plurality of non-consumable anodes and cathodes are disposed in the electrolyte and an electric current is passed through the anodes and through the electrolyte to the cathodes depositing aluminum on the cathodes and generating oxygen bubbles at the anodes, the bubbles stirring the electrolyte. Periodically, the electric current flow to the cell is reduced for extended periods.

Abstract: A bipolar cell for the electrowinning of aluminium has bipolar electrodes each comprising a carbon cathode body having on one side an active surface on which aluminium is produced and connected on the other side through an oxygen impermeable barrier layer to an electrochemically active anode layer having an oxygen evolving iron oxide-based outer surface. The anode layer may comprise a metal-based anode substrate and a transition metal oxide-based outside layer, in particular an iron oxide-based outside layer, which either is an applied layer or is obtainable by oxidising the surface of the anode substrate which contains iron. During operation, the anode layer can be kept dimensionally stable by maintaining in the electrolyte a concentration of transition metal species which are present as one or more corresponding transition metal oxides in the electrochemically-active layer.

Abstract: An anode of a cell for the electrowinning of aluminium comprises an iron-nickel alloy body or layer whose surface is oxidised to form a coherent and adherent outer iron oxide-based layer, in particular hematite, the surface of which is electrochemically active for the oxidation of oxygen ions and which reduces diffusion of oxygen from the electrochemically active surface into the iron-nickel alloy body or layer. The anode may be kept dimensionally stable during cell operation by maintaining a sufficient amount of dissolved alumina and iron species in the electrolyte to prevent dissolution of the outer oxide layer of the or each anode and by reducing the electrolyte operating temperature to limit dissolution of iron and by reducing the electrolyte operating temperature to limit dissolution of iron species in the electrolyte.

Abstract: A cell for the electrowinning of aluminium comprising one or more anodes (10), each having a metal-based anode substrate, for instance comprising a metal core (11) covered with an metal layer 12, an oxygen barrier layer (13), one or more intermediate layers (14; 14A, 14B) and an iron layer (15). The anode substrate is covered with an electrochemically active transition metal oxide layer, in particular an iron oxide-based outside layer (16) such as a hematite-based layer, which remains dimensionally stable during operation in a cell by maintaining in the electrolyte a sufficient concentration of iron species and dissolved alumina. The cell operating temperature is sufficiently low so species and dissolved alumina.

Abstract: A method of treating an electrolyte for use in the electrolytic reduction of alumina to aluminum employing an anode and a cathode, the alumina dissolved in the electrolyte, the treating improving wetting of the cathode with molten aluminum during electrolysis. The method comprises the steps of providing a molten electrolyte comprised of ALF3 and at least one salt selected from the group consisting of NaF, KF and LiF, and treating the electrolyte by providing therein 0.004 to 0.2 wt. % of a transition metal or transition metal compound for improved wettability of the cathode with molten aluminum during subsequent electrolysis to reduce alumina to aluminum.

Abstract: A method of preparing carbonaceous blocks or bodies for use in a cathode in an electrolytic cell for producing aluminum wherein the cell contains an electrolyte and has molten aluminum contacting the cathode, the cathode having improved wettability with molten aluminum. The method comprises the steps of providing a carbonaceous block and a boron oxide containing melt. The carbonaceous block is immersed in the melt and pressure is applied to the melt to impregnate the melt into pores in the block. Thereafter, the carbonaceous block is withdrawn from the melt, the block having boron oxide containing melt intruded into pores therein, the boron oxide capable of reacting with a source of titanium or zirconium or like metal to form titanium or zirconium diboride during heatup or operation of said cell.

Abstract: A cermet inert anode having a reduced level of contaminating surface metal is disclosed. Methods for preparing cermet inert anodes and methods for treating cermet inert anodes are also disclosed. The methods generally use an oxidizing agent to convert metals on the surface of the anode to inert oxides and/or to otherwise remove the metal contaminants. The inert anodes of the present invention may be used in electrolytic reduction cells for the production of commercial purity aluminum, as well as other metals.

Abstract: A cermet inert anode having a reduced level of contaminating surface metal is disclosed. Methods for preparing cermet inert anodes and methods for treating cermet inert anodes are also disclosed. The methods generally use an oxidizing agent to convert metals on the surface of the anode to inert oxides and/or to otherwise remove the metal contaminants. The inert anodes of the present invention may be used in electrolytic reduction cells for the production of commercial purity aluminum, as well as other metals.

Abstract: A non-carbon, metal-based slow-consumable anode of a cell for the electrowinning of aluminium self-forms during normal electrolysis an electrochemically-active oxide-based surface layer (20). The rate of formation (35) of the layer (20) is substantially equal to its rate of dissolution (30) at the surface layer/electrolyte interface (25) thereby maintaining its thickness substantially constant, forming a limited barrier controlling the oxidation rate (35). The anode (10) usually comprises an alloy of iron with at least one of nickel, copper, cobalt or zinc which during use forms an oxide surface layer (20) mainly containing ferrite.

Abstract: A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte. A plurality of non-consumable anodes are disposed substantially vertically in the electrolyte along with a plurality of monolithic hollow cathodes. Each cathode has a top and bottom and the cathodes are disposed vertically in the electrolyte and the anodes and the cathodes are arranged in alternating relationship. Each of the cathodes is comprised of a first side facing a first opposing anode and a second side facing a second opposing anode. The first and second sides are joined by ends to form a reservoir in the hollow cathode for collecting aluminum therein deposited at the cathode.

Abstract: A cermet inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode comprises a ceramic phase including an oxide of Ni, Fe and M, where M is at least one metal selected from Zn, Co, Al, Li, Cu, Ti, V, Cr, Zr, Nb, Ta, W, Mo, Hf and rare earths, preferably Zn and/or Co. Preferred ceramic compositions comprise Fe2O3, NiO and ZnO or CoO. The cermet inert anode also comprises a metal phase such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. A preferred metal phase comprises Cu and Ag. The cermet inert anodes may be used in electrolytic reduction cells for the production of commercial purity aluminum as well as other metals.

Abstract: An inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode includes a ceramic oxide material preferably made from NiO, Fe2O3 and ZnO. The inert anode composition may comprise the following mole fractions of NiO, Fe2O3 and ZnO: 0.2 to 0.99 NiO; 0.0001 to 0.8 Fe2O3; and 0.0001 to 0.3 ZnO. The inert anode may optionally include other oxides and/or at least one metal phase, such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. The Ni—Fe—Co—O ceramic material exhibits very low solubility in Hall cell baths used to produce aluminum.

Abstract: A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten salt electrolyte in an electrolytic cell having an anodic liner for containing the electrolyte, the liner having an anodic bottom and walls including at least one end wall extending upwardly from the anodic bottom, the anodic liner being substantially inert with respect to the molten electrolyte. A plurality of non-consumable anodes is provided and disposed vertically in the electrolyte. A plurality of cathodes is disposed vertically in the electrolyte in alternating relationship with the anodes. The anodes are electrically connected to the anodic liner. An electric current is passed through the anodic liner to the anodes, through the electrolyte to the cathodes, and aluminum is deposited on said cathodes. Oxygen bubbles are generated at the anodes and the anodic liner, the bubbles stirring the electrolyte.

Abstract: Cathode connector means for low temperature aluminum smelting cell for connecting titanium diboride cathode or the like to bus bars.

Abstract: A method of producing commercial purity aluminum in an electrolytic reduction cell comprising ceramic inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The ceramic inert anodes used in the process may comprise oxides containing Fe and Ni, as well as other oxides, metals and/or dopants.

Abstract: A method of producing commercial purity aluminum in an electrolytic reduction cell comprising ceramic inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The ceramic inert anodes used in the process may comprise oxides containing Fe and Ni, as well as other oxides, metals and/or dopants.

Abstract: Carbon-containing components of cells for the production of aluminium by the electrolysis of alumina dissolved in a cryolite-based molten electrolyte are protected from attack by liquid and/or gaseous components of the electrolyte in the form of elements, ions or compounds, by a refractory boride coating applied from a slurry composed of pre-formed particulate refractory boride in a colloidal carrier which is dried and heated to consolidate the coating.

Abstract: An inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode includes a ceramic oxide material preferably made from NiO, Fe2O3 and CoO. The inert anode composition may comprise the following mole fractions of NiO, Fe2O3 and CoO: 0.15 to 0.99 NiO; 0.0001 to 0.85 Fe2O3; and 0.0001 to 0.45 CoO. The inert anode may optionally include other oxides and/or at least one metal phase, such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. The Ni—Fe—Co—O ceramic material exhibits very low solubility in Hall cell baths used to produce aluminum.

Abstract: A method of coating an electronically conductive and heat resistant substrate of an anode of a cell for the electrowinning of metals, in particular a cell for the electrowinning of aluminium, to protect and make the surface of the anode active for the oxidation of the oxygen ions present in the electrolyte. The method comprises applying onto the substrate a slurry comprising at least one oxide or oxide precursor as a non-dispersed but suspended particulate in a colloidal and/or inorganic polymeric carrier. The applied-slurry is then solidified and made adherent to the substrate upon heat treatment to form an adherent, protective, predominantly oxide-containing coating. The colloidal and/or inorganic polymeric carrier may comprise at least one of alumina, ceria, lithia, magnesia, silica, thoria, yttria, zirconia, tin oxide and zinc oxide. The oxide of the coating may be a chromite or a ferrite, such as a ferrite selected from cobalt, copper, manganese, nickel and zinc.

Abstract: A cell for the production of aluminium by the electrolysis of an aluminium compound dissolved in a molten electrolyte, in which an outer mechanical structure forming an outer shell (21) houses therein one or more inner electrically-conductive cathode holder shells or plates (31) which contain a cathode mass (32) and is/are connected electrically to the busbar. The cathode mass (32) has an aluminium-wettable top surface (37), preferably at a slope forming a drained cathode. The inner cathode holder shell or shells (31) is/are separated from the outer shell (21) by an electric and thermic insulation (40), the cathode holder shell(s) (31) also serving to distribute current uniformly to the cathode mass (32). The or each cathode (30) formed by the cathode holder shell (31) and cathode mass (32) is removable from the cell as a unit.