Abstract: A cell for the electrowinning of aluminium (50) from alumina dissolved in a molten electrolyte comprises a generally horizontal cell bottom (5), preferably aluminium-wettable, on which a pool of product aluminium (50) is collected from at least one electrically conductive cathodic element (10) having aluminium-wettable cathode surfaces (11). The cathodic element comprises an inclined cathodic wall (10) in the electrolyte (60) above the generally horizontal cell bottom (5). The cathodic wall (10) has an upwardly-oriented inclined face (11) that forms a sloping upper aluminium-wettable drained active cathode surface on which aluminium is produced and drains into the aluminium pool (50), and a downwardly-oriented inclined face (12) which is in contact with the molten electrolyte (60) and which overlies the aluminium pool (50). The aluminium pool (50) covers substantially the entire cell bottom (5) including underneath the cathodic wall (10).

Abstract: A cell for the electrowinning of aluminum (50) from alumina, comprises an inclined plate-like or grid-like open anode structure (25) which has a generally v-shaped configuration in cross-section. The anode structure (25) has a downwardly-oriented sloping electrochemically active surface that is generally v-shaped in cross-section and spaced above an upwardly-oriented corresponding sloping cathode surface (11) by an anode-cathode gap (40) in which alumina dissolved in a circulating electrolyte (60) is electrolysed. The anode structure (25) has a plurality of anode through-passages (45) distributed thereover for an up-flow of alumina-depleted electrolyte (60) from the anode-cathode gap (40).

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: 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: Object of the invention is an anodic structure for mercury cathode cells for the industrial electrolysis of sodium chloride. The new structure is constituted by a grid array comprising a multiplicity of vertically disposed and mutually parallel titanium blades, covered by an electrocatalytic coating specific for the discharge of chlorine. The ratio between the thickness and the height of the blades is comprised between 1:16 and 1:100 and the ratio between the surface of free passage between the blades and the projected surface is comprised between 15:17 and 25:30. The new grid array is perpendicularly fixed to new or existing frames having the function of mechanical support and current conduction to the grid array. Scope of the invention is simultaneously reducing the energetic consumption of the cell and the costs for restoring the exhausted electrocatalytic coating.

Abstract: A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising providing a molten salt electrolyte having alumina dissolved therein in an electrolytic cell. A plurality of anodes and cathodes having planar surfaces are disposed in a generally vertical orientation in the electrolyte, the anodes and cathodes arranged in alternating or interleaving relationship to provide anode planar surfaces disposed opposite cathode planar surfaces, the anode comprised of carbon. Electric current is passed through anodes and through the electrolyte to the cathodes depositing aluminum at the cathodes and forming carbon containing gas at the anodes.

Abstract: A drained-cathode cell for the electrowinning of aluminium comprises one or more anodes (14) suspended over one or more cathodes (16). The or each anode (14) and cathode (16) respectively have a sloped V-shaped active anode surface (22) and parallel sloped inverted V-shaped drained cathode surfaces (18) facing one another and spaced apart by two sloped inter-electrode gaps (20), arranged so the electrolyte circulates upwardly in the sloped inter-electrode gaps (20) assisted by anodically produced gas and then returns from a top part (22′) to a bottom part (22″) of each inter-electrode gap (20) along an electrolyte path (26,27,36,37).

Abstract: A refractory boride body or coating made of a boride of titanium, chromium, vanadium, ziconium, hafnium, niobium, tantalum, molybednum and cerium is produced from a slurry of the refractory boride or a precursor in a collidal carrier preferably composed of two more different grades of the same colloidal carrier selected from colloidal alumina, yttria, ceria, thoria, zirconia, magnesia, lithia, monoaluminum phosphate and cerium acetate. The slurry can also comprise an organic additive selected from polyvinyl alcohol; polyacrylic acid; hydroxyy propyl methyl cellulose; polythylene glycol; ethylene glycol, butyl benzyl phthalate; ammonium polymethacrylate and mixtures thereof. The retractory boride body or coated body is useful as a component of aluminum electrowinning cells.

Abstract: A cell for the electrowinning of aluminum using anodes (10) made from a alloy of iron with nickel and/or cobalt is arranged to produce aluminum of low contamination and of commercial high grade quality. The cell comprises a cathode (20) of drained configuration and operates at reduced temperature without formation of a crust or ledge of solidified electrolyte. The cell is thermally insulated using an insulating cover (65,65a,65b,65c) and an insulating sidewall lining (71). The molten electrolyte (30) is substantially saturated with alumina, particularly on the electrochemically active anode surface, and with species of at least one major metal present at the surface of the nickel-iron alloy based anodes (10). The cell is preferably operated at reduced temperature from 730° to 910° C. to limit the solubility of these metal species and consequently the contamination of the product aluminum.

Abstract: Inert anodes useful in electrolytic aluminum production cells are disclosed. The inert anodes have sloped bottom surfaces with controlled bubble release angles. In one embodiment, the bottom surface is substantially conical with a bubble release angle of up to 30 degrees. The cross-sectional size of the inert anodes is also controlled in order to maximize efficiency of the cells. The inert anodes may be provided in arrays in aluminum production cells in order to achieve commercial cell currents.

Abstract: A method of producing aluminum from alumina in an electrolytic cell including using a cathode comprised of a base material having low electrical conductivity and wettable with molten aluminum to form a reaction layer having a high electrical conductivity on said base layer and a cathode bar extending from said reaction layer through said base material to conduct electrical current from said reaction layer.

Abstract: A drained cathode cell for the electrowinning of aluminium comprises a cell bottom (20) arranged to collect product aluminium and thermic insulating sidewalls (55,55′) lined with a molten electrolyte resistant sidewall lining (50) which is made of material liable to react with molten aluminium, in particular containing silicon carbide, silicon nitride or boron nitride. The thermic insulating sidewalls (55,55′) inhibit formation of an electrolyte crust on the lining (50), whereby the lining (50) is exposed to molten electrolyte. The cell bottom (20) has a peripheral surface from which the insulating sidewalls (55,55′) extend generally vertically to form, with the cell bottom, a trough for containing molten electrolyte and aluminium produced on at least one drained cathode (32).

Abstract: A cell for the electrowinning of aluminium comprises a plurality of metal-based anodes facing and spaced part from an aluminium-wettable drained cathode surface on which aluminium is produced. The drained cathode surface is formed along the cell by upper surfaces of juxtaposed carbon cathode blocks, the cathode blocks extending across the cell. The drained cathode surface is divided into quadrants by a longitudinal aluminium collection groove along the cell and by a central aluminium collection reservoir across the cell. Pairs of quadrants across the cell are inclined in a V-shape relationship, the collection groove being located along the bottom of the V-shape and arranged to collect molten aluminium draining from the drained cathode surface and evacuate it into the aluminium collection reservoir during cell operation.

Abstract: In this cathode, which is a single block, the electrical resistivity is heterogeneous along its longitudinal axis, this resistivity being higher in the end regions of the cathode (3) than in the central region of the latter.

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 cell for the electrowinning of aluminium comprises at least one non-carbon metal-based anode (10) having an electrically conductive metallic structure (12, 13, 15) which is suspended substantially parallel to a facing cathode (20, 21, 22). Such metallic structure (12, 13, 15) comprises a series of parallel horizontal anode members (15), each having an electrochemically active surface (16) on which during electrolysis oxygen is anodically evolved. The electrochemically active surfaces (16) are in a generally coplanar arrangement to form the active anode surface. The anode members are spaced apart from one another by inter-member gaps forming flow-through openings (17) for the circulation of electrolyte (30) driven by the escape of anodically-evolved oxygen. The electrolyte (30) may circulate upwardly and/or downwardly in the flow-through openings (17) and possibly around the anode structure (12, 13, 15).

Abstract: This invention relates to the use of bubble-driven flow to enhance the dissolution and distribution of alumina in an aluminum electrolysis cell operating with inert anodes. By harnessing the driving force of bubbles rising along the sides of a sloped anode to induce circulation in a cell and by using a group of anodes to amplify the effect, alumina distribution can be maintained close to or at saturation without formation of muck/sludge. Alumina fed through point feeders at specific locations can be distributed throughout the entire cell rather than sinking to the bottom of the cell below the feed location. For a given circulation pattern, feeder locations can be optimized.

Abstract: An electrolytic bath for use during the electrolytic reduction of alumina to aluminum. The bath comprises a molten electrolyte having the following ingredients: (a) AlF3 and at least one salt selected from the group consisting of NaF, KF, and LiF; and (b) about 0.004 wt. % to about 0.2 wt. %, based on total weight of the molten electrolyte, of at least one transition metal or at least one compound of the metal or both. The compound may be, for example, a fluoride, oxide, or carbonate. The metal can be nickel, iron, copper, cobalt, or molybdenum. The bath can be employed in a combination that includes a vessel for containing the bath and at least one non-consumable anode and at least one dimensionally stable cathode in the bath. Employing the bath of the present invention during electrolytic reduction of alumina to aluminum can improve the wetting of aluminum on a cathode by reducing or eliminating the formation of non-metallic deposits on the cathode.

Abstract: An electrolytic cell for the electrowinning of aluminium comprises a cathode cell bottom provided with a series of sloped active cathode surfaces (11, 12) down which produced aluminium (60) is drained, and a series of recessed grooves or channels (20), below the bottom of the cathode active surfaces (11, 12) and extending therealong which collect and evacuate the drained produced aluminum (63). Preferably the active surfaces (11, 12) are V-shaped and the recessed grooves or channels (20) are provided with a sloping bottom and a constant cross-sectional area. Alumina is so fed into the cell as to supply alumina-rich electrolyte (62) into the recessed grooves or channels (20) which contain the alumina-rich electrolyte along substantially their entire length above the drained layer of aluminium (63).

Abstract: A cell for the electrowinning of aluminium comprises a plurality of metal-based anodes facing and spaced apart from an aluminium-wettable drained cathode surface on which aluminium is produced. The drained cathode surface is formed along the cell by upper surfaces of a series of juxtaposed carbon cathode blocks, the cathode blocks extending across the cell. The drained cathode surface is divided into quadrants by a longitudinal aluminium collection groove along the cell and by a central aluminium collection reservoir across the cell. Pairs of quadrants across the cell are inclined in a V-shape relationship, the collection groove being located along the bottom of the V-shape and arranged to collect molten aluminium draining from the drained cathode surface and evacuate it into the aluminium collection reservoir during cell operation.

Abstract: The invention relates to a method of producing aluminum in an electrolytic cell, particularly in a drained cell, such cell comprising a cathode (20) and facing anodes (10), each anode (10) being spaced apart in its operative position from the cathode (20) by an anode-cathode reduced distance defining an anode-cathode gap containing the bath being electrolyzed. The method comprises: feeding alumina into the electrolyte where it is dissolved; electrolyzing an alumina-rich bath in the anode-cathode gap; and periodically moving at least one anode (10) in order to intake rich-alumina electrolyte into the anode-cathode gap thereby distributing alumina-rich electrolyte under the entire anode surface.

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.

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 drained cathode cell for the electrowinning of aluminium comprises a cell bottom (20) arranged to collect product aluminium and thermic insulating sidewalls (40) lined with a molten electrolyte resistant sidewall lining (50), in particular containing silicon carbide, silicon nitride or boron nitride. The thermic insulating sidewalls (40) inhibit formation of an electrolyte crust on the lining (50), whereby the lining (50) is exposed to molten electrolyte. The cell bottom (20) has a peripheral zone from which the insulating sidewalls (40) extend generally vertically to form, with the cell bottom, a trough for containing molten electrolyte and aluminium produced on at least one drained cathode (32). The peripheral zone of the cell bottom (20) is arranged to keep the product aluminium from contacting and reacting with the molten electrolyte resistant sidewall lining 50).

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 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.