Abstract: A component of an aluminium production cell, in particular a cathode or a cell lining of an electrolytic cell for the production of aluminium by the electrolysis of alumina in cryolite, having an aluminium-wettable refractory coating on a heat-stable baked carbon-containing body, is produced from a part-manufactured cell component which is a layered composite of two precursors. A precursor layer of the aluminium-wettable refractory coating contains at least one aluminium-wettable refractory material in particulate form, or a particulate micropyretic reaction mixture which when ignited reacts to form at least one aluminium-wettable refractory material, or a mixture thereof, and non-carbon fillers and binders. A non-baked or part-baked precursor of the heat-stable carbon-containing body comprises particulate carbon compacted with a heat-convertible binder which when subjected to heat treatment binds the particulate carbon into the heat-stable carbon-containing body of the fully-manufactured cell component.

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: A non-carbon, metal-based anode (10) of a cell for the electrowinning of aluminium, comprising an electrically conductive, high temperature resistant and oxidation resistant metal structure (11) in the form of a wire mesh or net, a foraminate sheet, a fibrous network, a reticulated skeletal structure, or a porous structure having voids, recesses and/or pores which are filled or partly filled with an electrochemically active filling (12), such as oxides, oxyfluorides, phosphides, carbides, cobaltites and cuprates making the surface of the anode (10) conductive and electrochemically active for the oxidation of oxygen ions present at the anode surface/electrolyte (5) interface.

Abstract: A non-carbon, metal-based high temperature resistant anode of a cell for the production of aluminium has a metal-based substrate coated with one or more electrically conductive adherent applied layers, at least one electrically conductive layer being electrochemically active. The electrochemically active layer contains one or more electrocatalysts fostering the oxidation of oxygen ions as well as fostering the formation of biatomic molecular gaseous oxygen to inhibit ionic and/or monoatomic oxygen attack of the metal-based substrate. The electrocatalyst can be iridium, palladium, platinum, rhodium, ruthenium, silicon, tin, zinc, Mischmetal oxides and metals of the Lanthanide series. The applied layer may further comprise electrochemically active constituents from oxides, oxyfluorides, phosphides, carbides, in particular spinels such as ferrites.

Abstract: A method of producing a self-sustaining body of refractory boride from the group consisting of the borides of titanium, chromium, vanadium, zirconium, hafnium, niobium, tantalum, molybdenum and cerium. This body includes a refractory boride and a dried colloid from the group consisting of colloidal alumina, silica, yttria, ceria, thoria, magnesia, lithia, monoaluminium phosphate and cerium acetate and is obtained from a slurry of the refractory boride in one or more of said colloids by casting the slurry on a porous plaster layer, and drying the cast slurry by draining through the plaster, or by pressing/drying. Subsequently, the dried body is subjected to heat treatment to bond the refractory boride in the dried colloid. The bodies are useful as components of aluminium electrowinning cells.

Abstract: An electrolytic cell for the electrowinning of aluminium from alumina dissolved in a halide-containing molten electrolyte, has a cathode cell bottom made of a series of carbon cathode blocks (10) connected side-by-side by glue or ramming paste, each one provided with steel or other conductive bars (11) for the delivery of current and a series of anodes (15) facing the cathode cell bottom. The tops of the carbon blocks (10) forming the cathode cell bottom are shaped in such a way as to provide in the cell bottom a series of parallel channels (25) or grooves preferably coated with an aluminium-wettable refractory coating (35) covered in use by a pool (40) of molten aluminium or a layer of molten aluminium forming a drained surface. Movement of the aluminium pool (40) is decreased, cell operation improved and cell life extended.

Abstract: A composite, high-temperature resistant, non-carbon metal-based anode of a cell for the electrowinning of aluminium 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. These layers consist of at least one layer on the core structure constituting a barrier substantially impervious to monoatomic oxygen and molecular oxygen; one or more intermediate, protective layers on the oxygen barrier layer which remain inactive in the reactions for the evolution of oxygen gas; and an electrochemically active 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 oxygen.

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: A carbon body, in particular a pre-baked anode of an electrolytic cell for the production of aluminium by the electrolysis of alumina in a molten fluoride electrolyte is treated over its surfaces to improve the resistance thereof to deterioration during operation of the cell by air and oxidizing gases released at the anode, by treating the body with a treating liquid comprising a precipitable boron-containing compound and an additive, said additive being present in an amount so that substantially no separate phase from said the precipitate of said boron-containing compound is formed upon curing. Suitable boron oxide additives include colloidal alumina, silica, yttria, ceria, thoria, zirconia, magnesia, lithia, monoaluminium phosphate, cerium acetate and mixtures thereof. The same treatment can also be applied to a carbon mass forming a Soderberg anode and to cell sidewalls.

Abstract: An anode for the electrowinning of aluminium by the electrolysis of alumina dissolved in a molten fluoride electrolyte comprises a porous combustion synthesis product of nickel, aluminium, iron, copper and optional doping elements in the amounts 50-90 wt. % nickel, 3-20 wt. % aluminium, 5-20 wt. % iron, 0-15 wt. % copper and 0-5 wt. % of one or more of chromium, manganese, titanium, molybdenum, cobalt, zirconium, niobium, tantalum, yttrium, cerium, oxygen, boron and nitrogen. The combustion synthesis product contains metallic and intermetallic phases. A composite oxide surface is produced in situ by anodic polarization of the porous combustion synthesis product in a molten fluoride electrolyte containing dissolved alumina. The in situ formed composite oxide surface comprises an iron-rich relatively dense outer portion, and an aluminate-rich relatively porous inner portion.

Abstract: An electrolytic cell for the electrowinning of aluminum from alumina dissolved in a halide-containing molten electrolyte, has a cathode cell bottom made of a series of carbon cathode blocks (10) connected side-by-side by glue or ramming paste, each one provided with steel or other conductive bars (11) for the delivery of current and a series of anodes (15) facing the cathode cell bottom. The tops of the carbon blocks (10) forming the cathode cell bottom are shaped in such a way as to provide in the cell bottom a series of parallel channels (25) or grooves preferably coated with an aluminum-wettable refractory coating (35) covered in use by a pool (40) of molten aluminum or a layer of molten aluminum forming a drained surface. Movement of the aluminum pool (40) is decreased, cell operation improved and cell life extended.

Abstract: A cell for the production of aluminium by the electrolysis of a molten electrolyte, in particular the electrolysis of alumina dissolved in a molten fluoride-based electrolyte such as cryolite, comprises anodes immersed in the molten electrolyte above a cell bottom whereon molten product aluminium is collected in a pool containing bodies of aluminium-resistant material. Under the anodes are corresponding grids made of side-by-side upright or included walls aluminium-resistant material whose bottom ends stand on a ceramic-coated carbon cell bottom covered by the pool molten aluminium. The bottom ends of the grid walls form a base which is large compared to the height of the walls. Each grid on the cell bottom in stable manner during the operation of the cell and is easily removable from the cell and insertable in the cell.

Abstract: A method of producing a self-sustaining body of refractory boride from the group consisting of the borides of titanium, chromium, vanadium, zirconium, hafnium, niobium, tantalum, molybdenum and cerium. This body includes a refractory boride and a dried colloid from the group consisting of colloidal alumina, silica, yttria, ceria, thoria, magnesia, lithia, monoaluminium phosphate and cerium acetate and is obtained from a slurry of the refractory boride in one or more of said colloids by casting the slurry on a porous plaster layer, and drying the cast slurry by draining through the plaster, or by pressing/drying. Subsequently, the dried body is subjected to heat treatment to bond the refractory boride in the dried colloid. The bodies are useful as components of aluminium electrowinning cells.

Abstract: A carbon body, in particular a prebaked anode of an electrolytic cell for the production of aluminum by the electrolysis of alumina in a molten fluoride electrolyte, is treated over its surfaces to improve the resistance thereof to deterioration during operation of the cell by air and oxidizing gases released at the anode, by immersing the body in a treating liquid containing a soluble boron compound and at least one aluminum compound and/or at least one calcium compound as a powder, suspension or colloid or in solution, e.g. at 80.degree. to 120.degree. C. The same treatment can also be applied to a carbon mass forming a Soderberg anode and to cell sidewalls. The addition of the aluminum and/or calcium compound(s) increases strength and improves oxidation resistance compared to impregnation with boric acid alone.

Abstract: A component of an aluminum production cell, in particular a cathode or a cell lining of an electrolytic cell for the production of aluminum by the electrolysis of alumina in cryolite, having an aluminum-wettable refractory coating on a heat-stable baked carbon-containing body, is produced from a part-manufactured cell component which is a layered composite of two precursors. A precursor layer of the aluminum-wettable refractory coating contains at least one aluminum-wettable refractory material in particulate form, or a particulate micropyretic reaction mixture which, when ignited, reacts to form at least one aluminum-wettable refractory material, or a mixture thereof, and non-carbon fillers and binders. A non-baked or part-baked precursor of the heat-stable carbon-containing body comprises particulate carbon compacted with a heat-convertible binder which when subjected to heat treatment binds the particulate carbon into the heat-stable carbon-containing body of the fully-manufactured cell component.

Abstract: A cathode block of a cell for the electrowinning of aluminium comprises a carbon body having a hard and abrasion-resistant surface obtained by heating an applied layer of particulate refractory hard metal boride with a bonding material which when heated reacts with the refractory hard metal boride and with carbon. In particular a slurry of particulate refractory boride in colloidal alumina is dried and heated under an inert or a reducing atmosphere, formed by a bed of carbon powder, and reacted to form at least one stable compound between aluminium derived from colloidal alumina; boron and titanium derived from the titanium diboride; and carbon from the reducing atmosphere.

Abstract: An electrolysis cell for the production of aluminum by the electrolysis of alumina dissolved in a molten halide electrolyte using a multimonopolar arrangement of substantially non-consumable anodes and cathodes with facing operative surfaces which are upright or at a slope and are spaced in a substantially parallel relationship, enabling operation at low and/or current density with an acceptable production per unit self-lowered area. The operative surface area of the anodes and the cathodes is high due to their upright sloping configuration. Operative surfaces of the anodes and possibly of the cathodes can be increased by making them porous, preferably with their articulated skeletal structure, e.g. with a porous active part on opposite faces of a central current feeder.

Abstract: Components of aluminium production cells made of composite materials comprising ordered aluminide compounds of at least one of nickel, iron and titanium, for use in particular as anodes and cathodes and cell linings in aluminium production cells containing a fluoride-based molten electrolyte containing dissolved alumina and cerium species, are produced by micropyretic reaction of a reaction mixture comprising compacted particulate reactants which react to produce the composite material. The reaction mixture is mixed with a cerium-based colloidal carrier, dried and compacted into a reaction body bonded by the cerium-based colloidal carrier, and the colloid-bonded reaction body is ignited to initiate the micropyretic reaction.

Abstract: An electrolytic cell for the electrowinning of aluminium from alumina dissolved in a halide-containing molten electrolyte, has a cathode cell bottom made of a series of carbon cathode blocks (10) connected side-by-side by glue or ramming paste, each one provided with steel or other conductive bars (11) for the delivery of current and a series of anodes (15) facing the cathode cell bottom. The tops of the carbon blocks (10) forming the cathode cell bottom are shaped in such a way as to provide in the cell bottom a series of parallel channels (25) or grooves preferably coated with an aluminium-wettable refractory coating (35) covered in use by a pool (40) of molten aluminium or a layer of molten aluminium forming a drained surface. Movement of the aluminium pool (40) is decreased, cell operation improved and cell life extended.

Abstract: Carbon or carbon-based cathodes and cell bottoms of electrolytic cells for the production of aluminium in particular by the electrolysis of alumina in a molten halide electrolyte such as cryolite, are treated to better resist intercalation of sodium in the cell operating conditions by impregnation and/or coating with colloidal alumina, ceria, cerium acetate, lithia, yttria, thoria, zirconia, magnesia or monoaluminium phosphate followed by drying and heat treatment.