Aluminum Company of America

Other

Emec Consultants

C Norman Cochran

Melvin H Brown

Siba P Ray

Subodh K Das

Robert M Mazgaj

Richard A Milito

David B Stofesky

Robert K Dawless

Kenneth A Bowman

Perry A Foster, Jr

Noel Jarrett

Warren E Haupin

Rudolf Keller

David A Wohleber

Nancy M Fitzgerald

William C Sleppy

Walter W Hill

Rudolph Keller

Jagdish C Agarwal

David H De Young

William E Libent

A method of treating sodium cyanide in spent carbonaceous and/or refractory material, i.e., spent potlining, from an electrolytic cell for producing aluminum from alumina dissolved in a sodium-containing electrolyte, wherein sodium cyanide forms in the carbonaceous material during operation of the cell. The method comprises grinding the spent carbonaceous and/or refractory material containing sodium cyanide to provide particles of spent carbonaceous material and adding a reactive material capable of reacting with the sodium cyanide to provide a mixture of reactive material and spent potlining material. Thereafter, the mixture is heated to a temperature effective in reacting the reactive material with the sodium cyanide to destroy the sodium cyanide in the spent potlining.

Decomposition of cyanide in electrolytic cell lining

Disclosed is an improved carbonaceous material suitable for use as a liner in an aluminum producing electrolytic cell, the cell using an electrolyte comprised of sodium containing compounds and the carbonaceous material penetrable by sodium or nitrogen and resistant to formation or accumulation of sodium cyanide during operation of the cell. The carbonaceous material is comprised of carbon and a reactive compound capable of reacting with one of sodium, nitrogen and sodium cyanide during operation of the cell to produce aluminum, the reactive compound present in an amount sufficient to suppress formation or accumulation of cyanide compounds in the liner.

Suppression of cyanide formation in electrolytic cell lining

An in situ formed superconducting cermet comprising an interwoven matrix of a superconducting ceramic and a noble metal and a method of making same are disclosed. An initial mixture is formed comprising (1) a first reactant selected from the class consisting of one or more noble metals in an oxidized state, and a mixture of one or more oxidized noble metals and one or more noble metals; (2) one or more rare earth-bearing reactants selected from the class consisting of one or more rare earths in an oxidized state, one or more rare earths in elemental form, and a combination thereof; (3) one or more alkaline earth-bearing reactants selected from the class consisting of one or more alkaline earth metals in an oxidized state, one or more alkaline earth metals, and a combination thereof; and (4) a copper based reactant selected from the class consisting of copper oxide, an oxide of a copper base alloy, elemental copper, a copper base alloy, and a combination of two or more thereof; wherein at least one of said rare earth-bearing, alkaline earth metal-bearing, or copper based reactants is in elemental form. The mixture of reactants is reaction sintered together to reduce at least a portion of the first reactant and to oxidize at least a portion of the other reactants to form a superconducting cermet in situ consisting essentially of an interwoven matrix of a noble metal and a superconductive ceramic.

Superconducting cermet formed in situ by reaction sintering

An improved process is disclosed for carbothermically producing an alkaline earth metal aluminide from an aluminum-bearing material which, in one aspect comprises forming a mixture of a carbonaceous reducing agent and a slag comprising the aluminum-bearing material, the alkaline earth metal compound; forming, at a first temperature, an alloy containing impurities in the slag; removing the alloy containing the impurities from the slag; and then heating the slag to a higher temperature to form the alkaline earth metal aluminide. The alkaline earth metal compound used in the process may comprise calcium carbide. Alternatively, both the alkaline earth metal compound and the aluminum-bearing material may be obtained using a calcium aluminate slag such as a byproduct from the steel industry. The calcium aluminate slag is purified in a preliminary step to remove silicon by alloying it with iron and them removing a ferrosilicon alloy formed in this step. Byproducts formed during the reactions may be recycled back if desired. Either metallic aluminum, the alkaline earth metal, or both may be recovered from the aluminide material using, respectively a halide, a sulfurous, or a nitrogen stripping agent, or by reducing both metals in an electrolytic reduction cell. The alkaline earth metal aluminide may also be used as a reducing agent to recover other metals such as magnesium oxide by reduction from their respective compounds.

Process for carbothermic production of alkaline earth metal aluminide

An improved process is disclosed for carbothermically producing an alkaline earth metal aluminide from an aluminum-bearing material which, in one aspect comprises forming a mixture of a carbonaceous reducing agent and a slag comprising the aluminum-bearing material, the alkaline earth metal compound; forming, at a first temperature, an alloy containing impurities in the slag; removing the alloy containing the impurities from the slag; and then heating the slag to a higher temperature to form the alkaline earth metal aluminide. The alkaline earth metal compound used in the process may comprise calcium carbide. Alternatively, both the alkaline earth metal compound and the aluminum-bearing material may be obtained using a calcium aluminate slag such as a byproduct from the steel industry. The calcium aluminate slag is purified in a preliminary step to remove silicon by alloying it with iron and then removing a ferrosilicon alloy formed in this step. Byproducts formed during the reactions may be recycled back if desired. Either metallic aluminum, the alkaline earth metal, or both may be recovered from the aluminide material using, respectively a halide, a sulfurous, or a nitrogen stripping agent, or by reducing both metals in an electrolytic reduction cell. The alkaline earth metal aluminide may also be used as a reducing agent to recover other metals such as magnesium oxide by reduction from their respective compounds.

Process for carbothermic production of calcium aluminide using calcium

An improved process is disclosed for carbothermically producing an alkaline earth metal aluminide from an aluminum-bearing material which, in one aspect comprises forming a mixture of a carbonaceous reducing agent and a slag comprising the aluminum-bearing material, the alkaline earth metal compound; forming, at a first temperature, an alloy containing impurities in the slag; removing the alloy containing the impurities from the slag; and then heating the slag to a higher temperature to form the alkaline earth metal aluminide. The alkaline earth metal compound used in the process may comprise calcium carbide. Alternatively, both the alkaline earth metal compound and the aluminum-bearing material may be obtained using a calcium aluminate slag such as a byproduct from the steel industry. The calcium aluminate slag is purified in a preliminary step to remove silicon by alloying it with iron and then removing a ferrosilicon alloy formed in this step. Byproducts formed during the reactions may be recycled back is desired. Either metallic aluminum, the alkaline earth metal, or both may be recovered from the aluminide material using, respectively a halide, a sulfurous, or a nitrogen stripping agent, or by reducing both metals in an electrolytic reduction cell. The alkaline earth metal aluminide may also be used as a reducing agent to recover other metals such as magnesium oxide by reduction from their respective compounds.

Process for production of aluminum by carbothermic production of

Process for production of aluminum by carbothermic production of an

An improved process is disclosed for carbothermically producing an alkaline earth metal aluminide from an aluminum-bearing material which, in one aspect comprises forming a mixture of a carbonaceous reducing agent and a slag comprising the aluminum-bearing material, the alkaline earth metal compound; forming, at a first temperature, an alloy containing impurities in the slag; removing the alloy containing the impurities from the slag; and then heating the slag to a higher temperature to form the alkaline earth metal aluminide. The alkaline earth metal compound used in the process may comprise calcium carbide. Alternatively, both the alkaline earth metal compound and the aluminum-bearing material may be obtained using a calcium aluminte slag such as a byproduct from the steel industry. The calcium aluminate slag is purified in a preliminary step to remove silicon by alloying it with iron and then removing a ferrosilicon alloy formed in this step. Byproducts formed during the reactions may be recycled back if desired. Either metallic aluminum, the alkaline earth metal, or both may be recovered from the aluminide material using, respectively a halide, a sulfurous, or a nitrogen stripping agent, or by reducing both metals in an electrolytic reduction cell. The alkaline earth metal aluminide may also be used as a reducing agent to recover other metals such as magnesium oxide by reduction from their respective compounds.

Process for carbothermic production of calcium aluminide using slag

Process for production of alkaline earth metal by carbothermic

Process for reduction of metal compounds by reaction with alkaline earth

An improved process is disclosed for carbothermically producing an alkaline earth metal aluminide from an aluminum-bearing material which, in one aspect comprises forming a mixture of a carbonaceous reducing agent and a slag comprising the aluminum-bearing material, the alkaline earth metal compound, forming, at a first temperature, an alloy containing impurities in the slag; removing the alloy containing the impurities from the slag; and then heating the slag to a higher temperature to form the alkaline earth metal aluminide. The alkaline earth metal compound used in the process may comprise calcium carbide. Alternatively, both the alkaline earth metal compound and the aluminum-bearing material may be obtained using a calcium aluminate slag such as a byproduct from the steel industry. The calcium aluminate slag is purified in a preliminary step to remove silicon by alloying it with iron and then removing a ferrosilicon alloy formed in this step. Byproducts formed during the reactions may be recycled back if desired. Either metallic aluminum, the alkaline earth metal, or both may be recovered from the aluminide material using, respectively a halide, a sulfurous, or a nitrogen stripping agent, or by reducing both metals in an electrolytic reduction cell. The alkaline earth metal aluminide may also be used as a reducing agent to recover other metals such as magnesium oxide by reduction from their respective compounds.

Process for production of aluminum and alkaline earth metal by

A method for purifying aluminum that contains impurities, the method including the step of introducing such aluminum containing impurities to a charging and melting chamber located in an electrolytic cell of the type having a porous diaphragm permeable by the electrolyte of the cell and impermeable to molten aluminum. The method includes further the steps of supplying impure aluminum from the chamber to the anode area of the cell and electrolytically transferring aluminum from the anode area to the cathode through the diaphragm while leaving impurities in the anode area, thereby purifying the aluminum introduced into the chamber. The method includes the further steps of collecting the purified aluminum at the cathode, and lowering the level of impurities concentrated in the anode area by subjecting molten aluminum and impurities in said chamber to a fractional crystallization treatment wherein eutectic-type impurities crystallize and precipitate out of the aluminum. The eutectic impurities that have crystallized are physically removed from the chamber. The aluminum in the chamber is now suited for further purification as provided in the above step of electrolytically transferring aluminum through the diaphragm.

Process of electrolysis and fractional crystallization for aluminum

A method for production of aluminum by carbothermic reduction of Al.sub.2 O.sub.3 in a stack-type reactor. A charge of Al.sub.2 O.sub.3 and C is inserted into an upper reaction zone of the reactor and reacted at an elevated temperature to form CO and a first liquid comprising Al.sub.2 O.sub.3 and Al.sub.4 C.sub.3. The first liquid is transferred to a lower reaction zone beneath the upper reaction zone and heated to form CO and a second liquid of Al and C. A portion of the second liquid is removed, and liquid Al is extracted therefrom. In a preferred method, Al.sub.2 O.sub.3 and C in the upper zone are heated by partial combustion of the C, and the lower zone is heated electrically. Gaseous Al and Al.sub.2 O formed in the lower zone are reclaimed in the upper zone. Gaseous CO produced in both zones heats the Al.sub.2 O.sub.3 and C in the upper zone. Excess CO is removed from the upper zone and used for generation of electricity or chemical process use. Liquid Al.sub.4 C.sub.3 separated from the second liquid is returned to the upper zone. Production of 1.00 kg Al requires an expenditure of 32.7 megajoules (MJ) of electrical energy, and 3.45 kg C. Total consumption of electrical energy and carbon energy equivalent is 121 MJ/kg Al, compared with 186 MJ/kg Al using the best Bayer-Hall technology.

Energy efficient production of aluminum by carbothermic reduction of

A process for purifying aluminum alloys comprises providing molten aluminum alloy in a container having a porous wall therein capable of containing molten aluminum in the container and being permeable by the molten electrolyte. Aluminum is electrolytically transported through the porous wall to a cathode thereby substantially separating the aluminum from alloying constituents.

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Oakmont, PA, United States of America

C Norman Cochran