Abstract: A non-carbon, metal-based, high temperature resistant, electrically conductive and electrochemically active anode of a cell for the production of aluminum has a metal-based oxidation-resistant substrate to which an adherent multi-layer coating is applied prior to its immersion into the electrolyte and start up of the electrolysis by connection to the positive current supply. The multi-layer coating is obtainable from one or more applied layers selected from: a liquid solution, a dispersion in a liquid or a paste, a suspension in a liquid or a paste, and a pasty or non-pasty slurry, and combinations thereof, with or without heat treatment between two consecutively applied layers. At least one layer of the multi-layer coating contains a polymeric and/or a colloidal carrier. The coating is after final heat treatment electrically conductive and has during operation in the cell an electrochemically active surface for the oxidation of oxygen ions present at the surface of the anode.

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: Insulation assemblies provide reduced heat loss from electrolytic metal production cells such as inert anode aluminum production cells. The insulation assemblies may be located at the end, side and/or center aisles of the cell, and may be supported by the anodes and deckplate of the cell. The assemblies reduce heat loss and bath vaporization losses, and permit stable operation of the inert anode cell.

Abstract: An electrolytic cell for aluminum production, including a cell wall, a bus bar, a carbonaceous cathode block, and a collector bar connecting the bus bar with the cathode block. The collector bar comprises a ferrous metal body including a solid spacer and a sheath defining a cavity containing a copper insert. The spacer has an external end portion connected with the bus bar and an internal end portion that is preferably spaced inwardly of the cell wall. The spacer separates the copper insert from the bus bar, thereby reducing heat loss from the cell.

Abstract: The present invention refers to an anode composition comprising as binding agent the sugar cane molasses, mascavo sugar, brown sugar or demerara, VHP, crystal, refined or hard sugar, instead of the conventional electrolytic pitch. The composition may optionally include additives based on lithium, fluorine, aluminum, boron and sulfur, and is used in a process for the manufacture of anodes for the primary aluminum industry. The invention also refers to a process for the manufacture of said anode and the application thereof to the primary aluminum industry.

Abstract: A sensor for detecting analytes is described. Analyte presence or concentration is determined through measurement of changes in induced electromotive force, current or other electrical property in a base member during analyte exposure to the sensor. According to one class of embodiments, the present device immobilizes natural or synthetic macromolecules sufficiently close to an electrically-conductive base member to insure that any alteration in the motion and/or electrostatic fields of the macromolecules during interaction with a predetermined analyte will induce an increased electromotive force in the base member.

Abstract: A method is provided for retrofitting conventional aluminum smelting cells with inert anode assemblies which replace the consumable carbon anodes of the cell. The inert anode assemblies are pre-heated prior to introduction into the operating cell. Insulation may be installed for reducing heat loss during operation of the retrofit cells.

Abstract: Conventional aluminum smelting cells are retrofitted with inert anode assemblies which replace the consumable carbon anodes of the cell. The inert anode assemblies may include multiple inert anodes, and may also include insulation for reducing heat loss during operation of the retrofit cells.

Abstract: A cathode assembly for use in a Hall-Heroult electrolytic cell, the assembly including a cathode block which receives two primary cathode collector bars and one secondary cathode collector bar disposed therebetween. The primary collector bars each have an electrical interface with the cathode block which is sized to be equal to or greater than an electrical interface between the secondary collector bar and the cathode block. The primary collector bars are electrically connected to the cathode block only along an interior portion of the cathode block and the secondary collector bar is fully connected to the cathode block. This arrangement improves current distribution through the cathode assembly by minimizing the amount of current passing through the ends of the cathode block.

Abstract: An anode of a cell for the electrowinning of aluminum comprises an iron-nickel alloy body or layer whose surface is oxidized 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: 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: The present invention refers to an anode composition comprising as binding agent the sugar cane molasses instead of the conventional electrolytic pitch. The composition may optionally include additives based on lithium, fluorine, aluminum, boron and sulfur, and is used in a process for the manufacture of anodes for the primary aluminum industry. The invention also refers to a process for the manufacture of said anode and the application thereof to the primary aluminum industry.

Abstract: The smelting of aluminum from alumina in the Hall-Heroult process can be dramatically improved by lowering power consumption and in the use of carbon free anodes by using a feed of positively charged alumina. Laboratory experiments have shown that the apparent solubility and reactivity of alumina in molten fluoride baths is surprisingly increased by altering the negatively charged aluminum hydroxide Al(OH)4− particles, at about pH of nine, to positively charged particles containing Al+++ with a pH of less than two, by using acid solutions. The alumina thus produced is referred to as Al+++ alumina, or positively charged alumina. In particular, sulfuric acid is used to convert aluminum hydroxide using the Bayer process to a family of basic aluminum sulfates, 3Al2O3.4SO3.9H2O, which are dehydrated and calcined to produce Al+++ alumina.

Abstract: A method of producing commercial purity aluminum in an electrolytic reduction cell comprising inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The inert anodes used in the process preferably comprise a cermet material comprising ceramic oxide phase portions and metal phase portions.

Abstract: An electrolytic cell and electrolytic process for producing a metal by reduction of a metal oxide dissolved in a molten salt bath containing at least one chloride and at least one fluoride. A solid conductor of oxide ions is interposed between the anode and the cathode. The solid conductor preferably comprises zirconia, stabilized in cubic form by addition of a divalent or trivalent metal oxide such as yttria.

Abstract: The present invention includes uranium-bearing ceramic phase electrodes and electrolysis apparatus and electrolysis methods featuring same, including methods of metal production and the like by the electrolytic reduction of oxides or salts of the respective metals. More particularly, the invention relates to an inert type electrode composition, and methods for fabricating electrode compositions, useful in the electrolytic production of such metals. The present invention also includes an inert-type electrode composition, and methods for fabricating electrode compositions, used in processes for generating energy from fossil fuels.

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: The device described herein is an enzyme-based biosensor for detecting and/or quantifying molecules of interest. The biosensor relies on the following properties shared by all enzymes: (1) that enzymes are highly specific molecules designed to bind with only one analyte type or one class of analyte molecules; (2) that enzymes contain charges; (3) that enzymes undergo significant spacial fluctuation during periods of interaction with substrates; and (4) that these spacial fluctuations cause the charged moieties on the enzyme to move and thus generate a measurable electrostatic potential (voltage) in both the enzyme and support layers. The instant device determines analyte presence/concentration through measurement of changes in voltage or current in a conducting or semiconducting support material as a result of changes in the position of immobilized charged enzyme molecules during their interaction with analyte.

Abstract: A Process for the electrolytic production of metals particularly titanium and alloys starting from the corresponding compounds is disclosed, by means of an apparatus for the electrochemical extraction including: (1) a cathode-crucible containing a mass of solidified metal, a liquid electrolyte with a density which is lower than that of the metal and a pool of liquid metal produced; (2) one or more non-consumable anodes particularly immersed in the electrolyte with means for regulating their distance from the cathodic surface; (3) a feeding system to the electrolyte of the compounds of the metals, of the electrolyte constituents and of alloying materials; (4) a power supply which feeds direct current to the liquid metal, and through the electrolyte, to the anodes, and causes the cathodic reduction of the metal in liquid form and the evolution of anodic gas, with the heat generation which maintains the electrolyte in the molten state; and (5) an air-tight containment structure in which the anodic gases generate

Abstract: A method is provided for the electrolytic production of aluminum metal from aluminum trichloride starting material. A molten electrolytic solution of mixed chloride-fluoride salts is formed in a reaction vessel into which the aluminum trichloride feed material is added. The fluoride component of the electrolyte reacts spontaneously with the aluminum trichloride, producing aluminum fluoride and a chloride salt. The aluminum fluoride is advantageously stored in a non-volatile state in solution in the electrolyte. The aluminum fluoride is then electrolytically reduced to yield aluminum metal and a fluoride salt.

Abstract: The present invention concerns a procedure for continuous or batch production in one or possibly more steps in one or more furnaces of silicon metal (Si), possibly silumin (AlSi alloys) and/or aluminium metal (Al) in the required conditions in a melting bath, preferably using feldspar or feldspar containing rocks dissolved in a fluoride and process equipment for implementing the procedure. Highly pure silicon is produced by electrolysis (step I) in a first furnace comprising a replaceable carbon anode (3) located at the bottom of the furnace and a carbon cathode (1) located at the top of the furnace. For the production of silumin the Si-poor residual electrolyte from step I is transferred to a second furnace and aluminium metal is added (step II). Aluminium metal is produced in a third furnace (step III) by electrolysis after Si has been removed in step I and possibly in step II.

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 connection assembly for the cathode of an aluminum smelter pot (10) including at least one insert (30) received within a hole in the collector bar (16) of a collector bar/strap (16/15) connection for the cathode and in electrical contact with the collector bar (16) and in electrical contact with the strap (15) via tab (15a).

Abstract: A method of making activated alumina includes beginning with a leach liquor of potassium and aluminum sulphates that is subjected to a surface-cooled crystallizer with a heat-exchanger input temperature of 160.degree. F. and a surface-chilled temperature of 60.degree. F. Crystals of aluminum sulphate are precipitated and recrystalized by evaporation in a vacuum and at an elevated temperature. Purified crystals of aluminum sulphate are then dried at 50.degree.-60.degree. C. The dried aluminum sulphate crystals are then dehydrated at 400.degree.-450.degree. C. after a rise rate of 50.degree.-60.degree. C. per minute to drive off most of the water. A roasting and recalcination step at 1000.degree. C.-1050.degree. C. after a rise rate of 50.degree.-60.degree. C. per minute is used drive off the sulphate. The remaining alumina is smelted by electrolysis for aluminum.

Abstract: An aluminium smelting cell comprising side walls (5) and a floor (2) defining an active cathode, an anode (3) overlying the cathode floor (2), some said side walls (5) being covered by a wetted cathode material (6), such as one contained TiB.sub.2, so that the covered side walls become active cathode surfaces on which a film of aluminium metal forms to protect the side wall parts against bath attack, thereby enabling the cell to operate at the desired temperatures without the usual protective side ledge of the frozen electrolyte material.

Abstract: In the electrolytic production of magnesium from an electrolyte comprising magnesium chloride and impurity quantities of magnesium oxide which adversely affects the efficiency of cell operation, the magnesium oxide is chemically and electrolytically removed from the electrolyte by sparging the electrolyte with hydrogen and/or hydrocarbon gas adjacent the anode such that MgO reacts with H.sub.2 or, e.g., CH.sub.4 and Cl.sub.2 (generated at the anode) under the electrical potential of the cell to form magnesium chloride. Similarly, magnesium oxide may be mixed and stirred in molten magnesium chloride and reacted with Cl.sub.2 and H.sub.2 (and/or hydrocarbon) to form anhydrous MgCl.sub.2 for use in magnesium production.

Abstract: An electrolytic reduction cell for the production of metal is provided, in which liquid metal is deposited at or adjacent an upper surface of a cathode. The electrolytic reduction cell includes an anode structure and a cathode located beneath the anode structure, wherein an upper portion of the cathode comprises an aggregate of particles sized and shaped such that in operation of the cell liquid metal is present in at least an upper part of the aggregate and a slurry of liquid metal and particles is established, the slurry comprising a substantially uniform dispersion of the particles in a continuous liquid phase of the liquid metal, the slurry having a viscosity sufficiently high such that under operating conditions of the cell the slurry is relatively immobile. Methods for the production of a metal by electrolysis in the electrolytic cell are also provided.

Abstract: Carbon-containing components (1, 2, 5) of cells for the production of aluminium (8) by the electrolysis of alumina dissolved in a cryolite-based molten electrolyte (7) are protected from attack by liquid and/or gaseous components of the electrolyte (7) in the form of elements, ions or compounds, by a refractory boride coating (9, 10, 11) applied from a slurry composed of preformed particulate refractory boride in a colloidal carrier which is dried and heated to consolidate the coating.

Abstract: A cell for the electrowinning of aluminium by the electrolysis of alumina dissolved in a molten fluoride-based electrolyte comprises a cathode composed of a carbon body having an aluminium resistant aluminium-wettable surface layer containing particulate titanium or other refractory hard metal boride and a bonding material providing a porous layer which contains cathodic molten aluminium. Molten cathodic aluminium external to the aluminium-resistant and aluminium-wettable surface contains refractory hard metal and boron in a total concentration sufficient or just below that sufficient to inhibit dissolution into the molten aluminium of the refractory hard metal boride. Alumina is fed to the cell whereby the required amount of titanium in the aluminium results from the alumina feed while, when boron is not present in a sufficient amount, boron is added to bring the total titanium and boron content to or just below the equilibrium solubility product.

Abstract: A process for obtaining aluminum of purity above 99.998%. A liquid aluminum raw material is subjected to a fractional crystallization to obtain prepurified aluminum crystals in a yield of between 50 and 80% and a liquid aluminum portion of lesser purity. The prepurified aluminum crystals are subjected to a three-layer electrolysis process in which the uppermost layer comprises a cathodic purified aluminum layer. The aluminum of purity above 99.998% is removed from the uppermost layer at a yield of above 90%, the aluminum having a total rare earth content of less than 100 ppb and a total content of U+Th of less than 20 ppb.

Abstract: Carbon-containing components of cells for the production of aluminum 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 treatment composition which consists essentially of a solution of one or more phosphates of aluminum. The treatment composition may alternatively consist essentially of one or more phosphates of aluminum, and one on more colloidal carriers.

Abstract: Carbon-containing components of cells for the production of aluminum by the electrolysis of alumina dissolved in a cryolite-based molten electrolyte are protected from erosion by non-chemical attack due to movement of liquid and/or gaseous components of the electrolyte, 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 process for smelting aluminum from a mixture of a double salt potassium-aluminum sulfate 2KAl(SO.sub.4).sub.2 and aluminum sulfate Al.sub.2 (SO.sub.4).sub.3 with potassium sulfate K.sub.2 SO.sub.4 having a weight ratio of 2KAl(SO.sub.4).sub.2 to K.sub.2 SO.sub.4 in the range of 50/50 to 15/85. The mixture is heated to a eutectic temperature that makes it molten and electrolysis is used to precipitate out aluminum at the negative electrode and gases from SO.sub.4 ions at the positive electrode. A critical amount of a feed of 2KAl(SO.sub.4).sub.2 is added to replace that which was consumed in the electrolysis and to maintain the weight ratio which provides for the low eutectic melting temperature.