US4650552A — Electrolytic production of aluminum

Claim 1

Independent Claim 46 words

A method of electrorefining aluminum comprising cathodically forming purified molten aluminum in an electrorefining cell, characterized in that at least a part of the cell in contact with the purified aluminum is made of a composite alumina-aluminum material composed of alumina and aluminum of pure grades.

Claim 2

Independent Claim 46 words

A method of electrorefining aluminum comprising cathodically forming purified molten aluminum in an electrorefining cell, characterized in that at least a part of the cell in contact with the purified aluminum is made of a composite alumina-aluminum material composed of alumina and aluminum of pure grades.

Claim 3

Dependent Claim 60 words

An aluminum production cell comprising a component which in use is normally covered with molten aluminum, said component comprising at least one body having a surface and/or an inner part made of a composite aluminum-alumina material consisting essentially of 10-50 % by weight of essentially pure aluminum in the metallic state and the balance alumina of at least 98.5% purity.

Claim 4

Dependent Claim 60 words

An aluminum production cell comprising a component which in use is normally covered with molten aluminum, said component comprising at least one body having a surface and/or an inner part made of a composite aluminum-alumina material consisting essentially of 10-50 % by weight of essentially pure aluminum in the metallic state and the balance alumina of at least 98.5% purity.

Claim 5

Dependent Claim 28 words

An aluminum production electrolysis cell comprising one or more components with a surface and/or inner part made of a composite aluminum-aluminum oxycompound material as claimed in claim 2.

Claim 6

Dependent Claim 38 words

A method of producing aluminum by electrolysis in an electrowinning or an electrorefining cell, characterized by using a cell component with a surface and/or inner part made of a composite aluminum-aluminum oxycompound material as claimed in claim 2.

Claim 7

Dependent Claim 35 words

The method of producing aluminum of claim 4, in which the cell component is a cathode or cathode current feeder with a substantially horizontal surface which is drained to maintain a thin film of aluminum.

Claim 8

Dependent Claim 38 words

The method of producing aluminum of claim 4, in which the cell component is a cathode or cathode current feeder with a perpendicular or inclined surface facing an anode and down which a thin film of aluminum flows.

Claim 9

Dependent Claim 128 words

An aluminum production cell comprising a component which in use is normally covered with molten aluminum, said component comprising at least one body having a surface and/or inner part made of a composite material consisting essentially of: (a) essentially pure aluminum in the metallic state in an amount of 10-50% by weight of the composite material, (b) alumina in an amount whereby the total of (a) and (b) amounts to at least about 95% by weight of the composite material, and (c) up to about 5% by weight of the composite material of an agent assisting retention of aluminum at elevated temperatures, said agent being selected from lithium, magnesium, calcium, titanium, chromium, iron, cobalt, nickel, zirconium, hafnium and/or one or more diborides of titanium, zirconium, hafnium and niobium.

Claim 10

Dependent Claim 128 words

An aluminum production cell comprising a component which in use is normally covered with molten aluminum, said component comprising at least one body having a surface and/or inner part made of a composite material consisting essentially of: (a) essentially pure aluminum in the metallic state in an amount of 10-50% by weight of the composite material, (b) alumina in an amount whereby the total of (a) and (b) amounts to at least about 95% by weight of the composite material, and (c) up to about 5% by weight of the composite material of an agent assisting retention of aluminum at elevated temperatures, said agent being selected from lithium, magnesium, calcium, titanium, chromium, iron, cobalt, nickel, zirconium, hafnium and/or one or more diborides of titanium, zirconium, hafnium and niobium.

Claim 11

Dependent Claim 164 words

An aluminum production cell comprising a component which in use is normally covered with molten aluminum, said component comprising at least one body having a surface and/or inner part made of a composite material consisting essentially of: (a) essentially pure aluminum in the metallic state in an amount of 10-50% by weight of the composite material, (b) alumina in an amount of at least 10% and preferably at least 25% by weight of the composite material, the total of components (a) and (b) being at least about 50% by weight of the composite material, and (c) at least one nitride, boride, carbide and/or oxide which does not readily react with molten aluminum and which is selected from the groups consisting of hafnium, niobium and the Group IIA, IIIB and the rare earth oxides and their mixtures, wherein the total quantity of (c) is no more than about 50% and the oxide component thereof is no more than about 15% by weight of the composite.

Claim 12

Dependent Claim 164 words

An aluminum production cell comprising a component which in use is normally covered with molten aluminum, said component comprising at least one body having a surface and/or inner part made of a composite material consisting essentially of: (a) essentially pure aluminum in the metallic state in an amount of 10-50% by weight of the composite material, (b) alumina in an amount of at least 10% and preferably at least 25% by weight of the composite material, the total of components (a) and (b) being at least about 50% by weight of the composite material, and (c) at least one nitride, boride, carbide and/or oxide which does not readily react with molten aluminum and which is selected from the groups consisting of hafnium, niobium and the Group IIA, IIIB and the rare earth oxides and their mixtures, wherein the total quantity of (c) is no more than about 50% and the oxide component thereof is no more than about 15% by weight of the composite.

Claim 13

Dependent Claim 24 words

The aluminum production cell of claim 2, 7 or 8 in which the composite material is an electrically conductive part of a current-carrying component.

Claim 14

Dependent Claim 21 words

The aluminum production cell of claim 2, 7 or 8, in which the component is a cathode or cathode current feeder.

Claim 15

Dependent Claim 24 words

The aluminum production cell of claim 2, 7 or 8, in which the component is an anode current feeder of an aluminum electrorefining cell.

Claim 16

Dependent Claim 23 words

The aluminum production cell of claim 2, 7 or 8, in which the component is a current carrying part of a cell lining.

Claim 17

Dependent Claim 23 words

The aluminum production cell of claim 2, 7 or 8, in which the component is a separator wall, weir, packing element or baffle.

Claim 18

Dependent Claim 42 words

The aluminum production cell of claim 8, in which the composite material is obtained by reacting aluminum with one or more suitable oxides to produce alumina in situ with an excess of unreacted aluminum and a reduced form of the starting oxide(s).

Claim 19

Dependent Claim 34 words

The aluminum production cell of claim 2, 7, 8 or 14, in which the composite material is obtained by hot pressing particles at a temperature of from about 1000° C. to about 1600° C.

Claim 20

Dependent Claim 50 words

The aluminum production cell of claim 2, 7, 8 or 14, in which the composite material is obtained by cold pressing particles into a pre-formed body and subjecting the pre-formed cold pressed particles to heat treatment prior to fitting the component in the cell or in situ in the cell.

Claim 21

Dependent Claim 28 words

The aluminum production cell of claim 2, 7 or 8 in which an exposed surface of the component is at least partly coated with another aluminum wettable material.

Claim 22

Independent Claim 128 words

The method of preparing a component which in use is normally present in an aluminum production cell and covered with molten aluminum, said component comprising at least one body having a surface and/or an inner part made of a composite aluminum-alumina material, which method comprises: (a) selecting an essentially pure alumina of sufficient porosity to provide 10-50 weight percent aluminum in the metallic state within said component; (b) pretreating said porous alumina at a temperature within the range of from about 800° C. to about 1700° C. under vacuum, or inert or reducing atmosphere; and (c) contacting the resulting pretreated porous alumina with essentially pure molten aluminum in an amount sufficient to prepare said composite aluminum-alumina material containing said 10-50 weight percent of aluminum in the metallic state.

Claim 23

Independent Claim 128 words

The method of preparing a component which in use is normally present in an aluminum production cell and covered with molten aluminum, said component comprising at least one body having a surface and/or an inner part made of a composite aluminum-alumina material, which method comprises: (a) selecting an essentially pure alumina of sufficient porosity to provide 10-50 weight percent aluminum in the metallic state within said component; (b) pretreating said porous alumina at a temperature within the range of from about 800° C. to about 1700° C. under vacuum, or inert or reducing atmosphere; and (c) contacting the resulting pretreated porous alumina with essentially pure molten aluminum in an amount sufficient to prepare said composite aluminum-alumina material containing said 10-50 weight percent of aluminum in the metallic state.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1990-03-16	1990-09-15	1991-03-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1994-03-16	1994-09-15	1995-03-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1998-03-16	1998-09-15	1999-03-17	$7700.00	Window Closed / Lapsed

Electrolytic production of aluminum

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