Abstract: A method for protecting anode assemblies in an electrolytic cell from thermal shock is disclosed. The method generally involves applying a thermal insulating layer (8, 16) to the anode (2) prior to preheating the anode assembly in a furnace, where the layer (8, 16) protects the anode (2) from thermal shock during transfer from the preheat furnace to the electrolytic cell. In a preferred embodiment the anode (2) is attached to a castable plate (4) that is also protected from thermal shock by an insulating layer.

Abstract: An inert anode 50, for use in an electrolytic cell 12 for producing metals such as aluminum, is made by providing chemical source materials 100 such as at least two of metal salts, metal particles, or metal oxides and dissolving them to form a solution or a slurry 110, followed by adding a base 120 and adjusting the pH so that a gel 130 is formed which is dried and calcined 150, 160, 190 to provide a blend of metal oxide powder 200 which can be pressed and sintered 220 to form an inert anode 50.

Abstract: Methods and apparatus are disclosed for reducing sulfur impurities in aluminum electrolytic production cells in order to significantly increase current efficiency of the cells. An impurity reduction zone may be created in the bath of an inert anode cell by submerging a purifying electrode in the bath. In another embodiment, an oxygen barrier tube may be disposed in a portion of the bath. In a further embodiment, reductants such as aluminum, CO and/or CO2 are added to the bath. In another embodiment, electrode current is interrupted or electrodes are removed from selected regions of the cell in order to allow gaseous impurities to escape from the bath. Sulfur impurity levels may also be reduced in inert anode cells by scrubbing bath emissions from the cell before they are reintroduced into the cell, and by controlling sulfur impurity contents of materials added to the cell.

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: Methods and apparatus are disclosed for reducing sulfur impurities in aluminum electrolytic production cells in order to significantly increase current efficiency of the cells. An impurity reduction zone may be created in the bath of an inert anode cell by submerging a purifying electrode in the bath. In another embodiment, an oxygen barrier tube may be disposed in a portion of the bath. In a further embodiment, reductants such as aluminum, CO and/or CO2 are added to the bath. In another embodiment, electrode current is interrupted or electrodes are removed from selected regions of the cell in order to allow gaseous impurities to escape from the bath. Sulfur impurity levels may also be reduced in inert anode cells by scrubbing bath emissions from the cell before they are reintroduced into the cell, and by controlling sulfur impurity contents of materials added to the cell.

Abstract: A method for protecting anode assemblies in an electrolytic cell from thermal shock is disclosed. The method generally involves applying a thermal insulating layer (8, 16) to the anode (2) prior to preheating the anode assembly in a furnace, where the layer (8, 16) protects the anode (2) from thermal shock during transfer from the preheat furnace to the electrolytic cell. In a preferred embodiment the anode (2) is attached to a castable plate (4) that is also protected from thermal shock by an insulating layer.

Abstract: An inert anode 50, for use in an electrolytic cell 12 for producing metals such as aluminum, is made by providing chemical source materials 100 such as at least two of metal salts, metal particles, or metal oxides and dissolving them to form a solution or a slurry 110, followed by adding a base 120 and adjusting the pH so that a gel 130 is formed which is dried and calcined 150, 160, 190 to provide a blend of metal oxide powder 200 which can be pressed and sintered 220 to form an inert anode 50.

Abstract: A method for protecting anode assemblies in an electrolytic cell from thermal shock is disclosed. The method generally involves applying a thermal insulating layer (8, 16) to the anode (2) and the castable plate (4) prior to preheating the anode assembly in a furnace, where the layer (8, 16) protects the anode (2) and the plate (4) from thermal shock during transfer from the preheat furnace to the electrolytic cell.

Abstract: A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000° C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

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: A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000° C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

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: Aluminum is produced by electrolytic reduction of alumina in a cell having a cathode, an inert anode and a molten salt bath containing metal fluorides and alumina. The inert anode preferably contains copper, silver and oxides of iron and nickel. Reducing the molten salt bath temperature to about 900-950.degree. C. lowers corrosion on the inert anode constituents.

Abstract: An electrolytic cell for reduction of a metal oxide to a metal and oxygen has an inert anode and an upwardly angled roof covering the inert mode. The angled roof diverts oxygen bubbles into an upcomer channel, thereby agitating a molten salt bath in the upcomer channel and improving dissolution of a metal oxide in the molten salt bath. The molten salt bath has a lower velocity adjacent the inert anode in order to minimize corrosion by substances in the bath. A particularly preferred cell produces aluminum by electrolysis of alumina in a molten salt bath containing aluminum fluoride and sodium fluoride.

Abstract: A low temperature salt bath for the electrolysis of metal oxides to produce the corresponding metal. The bath comprises a first salt, comprised of at least one fluoride salt, and a second salt, comprised of at least one chloride salt. The fluoride salt increases the metal oxide solubility in the molten salt bath, and the chloride salt reduces the bath liquidus temperature of the salt bath. The preferred process of practicing the invention includes using an anode consisting essentially of carbonaceous material and having an effective surface area about equal to the projected surface area of the anode.

Abstract: A continuous salt-based process is provided for melting and reclaiming aluminum from aluminum scrap containing impurities including heating a molten salt in a heat bay, mixing the heated salt with aluminum scrap or skim in a charge bay to form a molten charge mixture, separating aluminum from impurities in the charge bay by coalescing aluminum to form a molten aluminum metal pad, chlorinating a portion of the charge mixture from the charge bay to form a chlorinated salt mixture and metal chlorides, removing metal chlorides from the salt mixture, and feeding the salt mixture back to the heat bay. In one aspect, the chlorinating step of the present invention includes introducing carbon monoxide or, preferably, solid carbon to control oxide concentration. The process further comprises adding fluorides and removing metal chlorides from the salt to maintain a preferred salt composition.

Abstract: An improved electrolytic cell and process are provided wherein metals and metal alloys are formed from oxides or nitrides in a molten salt, without the evolution of halogen or halogen compounds, with less corrosion and reduced power consumption by the use of an electrode having an extended or substantially increased surface area effective for the evolution of oxygen and carbon oxide, and a molten salt electrolyte effective at low temperature.

Abstract: A container body for foods and beverages having reduced gas and vapor permeability. The container body is preferably formed from a plastic resin and coated with a thin film of diamond-like carbon.

Abstract: A process for decomposing chlorinated hydrocarbon compounds wherein the compounds are heated to an elevated temperature of about 800.degree. to 1200.degree. C. and reacted with alumina and a reactive carbon source. A preferred operating temperature is about 800.degree. to 900.degree. C. and preferred carbon sources are activated carbon and coked alumina. The process is particularly useful for disposing of chlorinated organic compounds that are generated in the production of metal chlorides by chlorination of a metal oxide in the presence of carbon.