US4173518A
Expired / Lapsed
US
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Electrodes for aluminum reduction cells
Assignee: Sumitomo Aluminum Smelting Co
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Filing: 1977-10-25
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Granted: 1979-11-06
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Expires: 1997-10-25
Abstract
Abstract An electrode for aluminum reduction cells wherein an electrode base, at least in that portion which is brought into contact with a molten salt bath, is coated with a composition comprising at least 50% by weight of electronic conductive oxide ceramics, or said portion of the electrode is made of said composition.
Inventors
- 👤 Koichi Yamada
- 👤 Tadanori Hashimoto
- 👤 Kazuo Horinouchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:46
CPC Classifications
C; C25; C25C; C25C3/00; C25C3/06; C25C3/08; C25C3/12
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
205 words
A method for producing aluminum by the molten salt electrolysis of aluminum oxide which comprises electrolyzing aluminum oxide dissolved in a molten salt containing aluminum sodium fluoride as the main component at a temperature of about 900° C. to about 1000° C. by passing a direct current therefor through an anode to a cathode disposed in said molten salt, wherein at least a portion of said anode that is brought into contact with said molten salt is made of or covered with a composition which includes at least about 50% by weight of electronic conductive oxide ceramics selected from one or a combination of oxides represented by general formulae XYO 2 wherein X is a monovalent metal, Y is a trivalent metal and O is an oxygen atom; D 2 E 2 O 7 wherein D is a trivalent metal, E is a tetravalent metal and O is an oxygen atom; and GRO 4 wherein G is a trivalent or tetravalent metal, R is a pentavalent or tetravalent metal and O is oxygen atom, with the proviso that when G is a trivalent metal then R is selected from pentavalent metals, and when G is a tetravalent metal then R is selected from tetravalent metals.
Claim 2
Independent Claim
205 words
A method for producing aluminum by the molten salt electrolysis of aluminum oxide which comprises electrolyzing aluminum oxide dissolved in a molten salt containing aluminum sodium fluoride as the main component at a temperature of about 900° C. to about 1000° C. by passing a direct current therefor through an anode to a cathode disposed in said molten salt, wherein at least a portion of said anode that is brought into contact with said molten salt is made of or covered with a composition which includes at least about 50% by weight of electronic conductive oxide ceramics selected from one or a combination of oxides represented by general formulae XYO 2 wherein X is a monovalent metal, Y is a trivalent metal and O is an oxygen atom; D 2 E 2 O 7 wherein D is a trivalent metal, E is a tetravalent metal and O is an oxygen atom; and GRO 4 wherein G is a trivalent or tetravalent metal, R is a pentavalent or tetravalent metal and O is oxygen atom, with the proviso that when G is a trivalent metal then R is selected from pentavalent metals, and when G is a tetravalent metal then R is selected from tetravalent metals.
Claim 3
Dependent Claim
41 words
The method of claim 1 wherein at least that portion of the electrode base which is brought into contact with the molten salt bath is coated with the composition including at least about 50% by weight of electronic conductive oxide ceramics.
Claim 4
Dependent Claim
41 words
The method of claim 1, wherein at least that portion of the electrode which is brought into contact with the molten salt bath is entirely made of the composition including at least about 50% by weight of electronic conductive oxide ceramics.
Claim 5
Dependent Claim
36 words
The method of claim 1, wherein oxide, nitride, boride or silicide of an element selected from transition metal, platinum group metal and rare earth element is added to the electronic conductive oxide ceramics as an additive.
Claim 6
Dependent Claim
24 words
The method of claim 1, wherein conductivity of the electronic conductive oxide ceramics is at least 0.1 Ω -1 cm -1 at 1000° C.
Claim 7
Dependent Claim
20 words
The method of claim 1, wherein melting point of the electronic conductive oxide ceramics is at or above 1200° C.
Claim 8
Dependent Claim
46 words
The method of claim 1, wherein the electronic conductive oxide ceramics is a delafossite structure oxide selected from the group consisting of PtCoO 2 , PtRhO 2 , PdCoO 2 , PdRhO 2 , PdNiO 2 , AgInO 2 , AgCoO 2 and AgRhO 2 .
Claim 9
Dependent Claim
246 words
The method of claim 1, wherein the electronic conductive oxides ceramics is a pyrochlore structure oxide selected from the group consisting of La 2 Ti 2 O 7 , La 2 Ir 2 O 7 , La 2 Sn 2 O 7 , La 2 Zr 2 O 7 , La 2 Ge 2 O 7 , La 2 Ru 2 O 7 , La 2 Os 2 O 7 , Y 2 Ti 2 O 7 , Y 2 Hf 2 O 7 , Y 2 Sn 2 O 7 , Y 2 Zr 2 O 7 , Y 2 Ge 2 O 7 , Y 2 Ru 2 O 7 , Y 2 Os 2 O 7 , Y 2 Ir 2 O 7 , Ce 2 Ti 2 O 7 , Ce 2 Sn 2 O 7 , Ce 2 Zr 2 O 7 , Ce 2 Ge 2 O 7 , Ce 2 Ru 2 O 7 , Ce 2 Os 2 O 7 , Ce 2 Hf 2 O 7 , Ce 2 Ir 2 O 7 , In 2 Ge 2 O 7 , In 2 Sn 2 O 7 , La 2 Pt 2 O 7 , Y 2 Pt 2 O 7 , Pr 2 Zr 2 O 7 , Nd 2 Zr 2 O 7 , Nd 2 Sn 2 O 7 , Sm 2 Zr 2 O 7 and Sn 2 Sm 2 O 7 .
Claim 10
Dependent Claim
43 words
The method of claim 1, wherein the electronic conductive oxides ceramics is a scheelite structure oxide selected from the group consisting of ZrGeO 4 , ThGeO 4 , ZrSnO 4 , LaTaO 4 , LaNbO 4 , YTaO 4 and YNbO 4 .
Claim 11
Dependent Claim
20 words
A method according to claim 1, wherein said composition includes at least 75% by weight of electronic conductive oxide ceramics.
Claim 12
Dependent Claim
28 words
The method of claim 1, wherein said electronic conductive oxide ceramic is a delafossite structure oxide selected from the group consisting of PbCoO 2 and PtCoO 2 .
Claim 13
Dependent Claim
36 words
The method of claim 1, wherein said electronic conductive oxide ceramic is a pyrochlore structure oxide selected from the group consisting of La 2 Sn 2 O 7 and La 2 Zr 2 O 7 .
Claim 14
Dependent Claim
37 words
The method of claim 1, wherein said electronic conductive oxide ceramic is a Scheelite structure oxide selected from the group consisting of ZrGeO 4 , ZrSnO 4 , and Zr(Ge 0 .4 Sn 0 .6)O 4 .
Claim 15
Independent Claim
306 words
A method for producing aluminum by the molten salt electrolysis of aluminum oxide which comprises electrolyzing aluminum oxide dissolved in a molten salt containing aluminum sodium fluoride as the main component at a temperature of about 900° C. to about 1000° C. by passing a direct current therefor through an anode to a cathode disposed in said molten salt, wherein at least a portion of said anode that is brought into contact with said molten salt is made of or covered with a composition which includes at least about 50% by weight of electronic conductive oxide ceramics selected from one or a combination of oxides represented by general formulae ##EQU12## where Ai and Bj are metal atoms, Q Ai and Q Bj are molar fractions of Ai and Bj constituents, respectively, O is an oxygen atom; K and l represent the numbers of metal constituents constituting Ai and Bj, respectively, and constituent ions at positions A and B meet the requirements of ##EQU13## wherein Q A and Q Bj are molar fractions of the atoms, n Ai and n Bj are valences of the atoms, γ Ai and γ Bj are ion radii of the atoms, and γ o is ion radius of oxygen); L a O b .Ta 2 O 5 wherein L is a divalent, trivalent or tetravalent metal, O is an oxygen atom, and if L is a divalent metal, then a=b=1, if L is a trivalent metal, then a=2, b=3, and if L is a tetravalent metal, then a=1, b=2; and M c O d .Nb 2 O 5 wherein M is a divalent, trivalent or tetravalent metal, O is an oxygen atom, and if M is a divalent metal, then c=d=1, and if M is a trivalent metal, then c=2, d-3, and if M is a tetravalent metal, then c-1, d=2.
Claim 16
Independent Claim
306 words
A method for producing aluminum by the molten salt electrolysis of aluminum oxide which comprises electrolyzing aluminum oxide dissolved in a molten salt containing aluminum sodium fluoride as the main component at a temperature of about 900° C. to about 1000° C. by passing a direct current therefor through an anode to a cathode disposed in said molten salt, wherein at least a portion of said anode that is brought into contact with said molten salt is made of or covered with a composition which includes at least about 50% by weight of electronic conductive oxide ceramics selected from one or a combination of oxides represented by general formulae ##EQU12## where Ai and Bj are metal atoms, Q Ai and Q Bj are molar fractions of Ai and Bj constituents, respectively, O is an oxygen atom; K and l represent the numbers of metal constituents constituting Ai and Bj, respectively, and constituent ions at positions A and B meet the requirements of ##EQU13## wherein Q A and Q Bj are molar fractions of the atoms, n Ai and n Bj are valences of the atoms, γ Ai and γ Bj are ion radii of the atoms, and γ o is ion radius of oxygen); L a O b .Ta 2 O 5 wherein L is a divalent, trivalent or tetravalent metal, O is an oxygen atom, and if L is a divalent metal, then a=b=1, if L is a trivalent metal, then a=2, b=3, and if L is a tetravalent metal, then a=1, b=2; and M c O d .Nb 2 O 5 wherein M is a divalent, trivalent or tetravalent metal, O is an oxygen atom, and if M is a divalent metal, then c=d=1, and if M is a trivalent metal, then c=2, d-3, and if M is a tetravalent metal, then c-1, d=2.
Claim 17
Dependent Claim
41 words
The method of claim 14, wherein at least that portion of the electrode base which is brought into contact with the molten salt bath is coated with the composition including at least about 50% by weight of electronic conductive oxide ceramics.
Claim 18
Dependent Claim
41 words
The method of claim 14, wherein at least that portion of the electrode which is brought into contact with the molten salt bath is entirely made of the composition including at least about 50% by weight of electronic conductive oxide ceramics.
Claim 19
Dependent Claim
36 words
The method of claim 14, wherein oxide, nitride, boride or silicide of an element selected from transition metal, platinum group metal and rare earth element is added to the electronic conductive oxide ceramics as an additive.
Claim 20
Dependent Claim
24 words
The method of claim 14, wherein conductivity of the electronic conductive oxide ceramics is at least 0.1 Ω -1 cm -1 at 1000° C.
Claim 21
Dependent Claim
20 words
The method of claim 14 wherein melting point of the electronic conductive oxide ceramics is at or above 1200° C.
Claim 22
Dependent Claim
201 words
The method of claim 14, wherein the electronic conductive oxide ceramics is a composite perovskite structure oxide selected from the group consisting of La(Ni 2/3 Ta 1/3 )O 3 , La(Ni 2/3 Nb 1/3 )O 3 , La(Pd 2/3 Ta 1/3 )O 3 , La(Pd 2/3 Nb 1/3 )O 3 , Y(Ni 2/3 Ta 1/3 )O 3 , Y(Ni 2/3 Nb 1/3 )O 3 , Y(Pd 2/3 Ta 1/3 )O 3 , Y(Pd 2/3 Nb 1/3 )O 3 , Bi(Ni 2/3 Ta 1/3 )O 3 , Bi(Ni 1/2 Zr 1/2 )O 3 , La(Ni 1/2 Pt 1/2 )O 3 , La(In 1/2 y 1/2 )O 3 , La(In 1/2 Al 1/2 )O 3 , La(Pd 1/2 Sn 1/2 )O 3 , Y(Pd 1/2 Sn 1/2 )O 3 , Bi(Pd 1/2 Sn 1/2 )O 3 , (Ag 1/2 Bi 1/2 )ZrO 3 , (Ag 1/2 Y 1/2 )SnO 3 , (Ag 1/2 La 1/2 ) (In 1/2 Ta 1/2 )O 3 , (Ag 1/2 Bi 1/2 ) (In 1/2 Nb 1/2 )O 3 , La(Y 1/2 Fe 1/2 )O 3 , La(Y 1/2 Mn 1/2 )O 3 , La(Fe 1/2 In 1/2 )O 3 and La(Fe 1/2 Mn 1/2 )O 3 .
Claim 23
Dependent Claim
104 words
The method of claim 14, wherein the electronic conductive oxide ceramics is a rutile structure oxide selected from the group consisting of CoO.Ta 2 O 5 , NiO.Ta 2 O 5 , ZnO.Ta 2 O 5 , SnO.Ta 2 O 5 , FeO.Ta 2 O 5 , Fe 2 O 3 .Ta 2 O 5 , Cr 2 O 3 .Ta 2 O 5 , Al 2 O 3 .Ta 2 O 5 , In 2 O 3 .Ta 2 O 5 , SnO 2 .Ta 2 O 5 , TiO 2 .Ta 2 O 5 and ZrO 2 .Ta 2 O 5 .
Claim 24
Dependent Claim
104 words
The method of claim 14, wherein the electronic conductive oxide ceramics is a columbite structure oxide selected from the group consisting of CoO.Nb 2 O 5 , NiO.Nb 2 O 5 , ZnO.Nb 2 O 5 , SnO.Nb 2 O 5 , FeO.Nb 2 O 5 , Fe 2 O 3 .Nb 2 O 5 , Cr 2 O 3 .Nb 2 O 5 , Al 2 O 3 .Nb 2 O 5 , In 2 O 3 .Nb 2 O 5 , SnO 2 .Nb 2 O 5 , TiO 2 .Nb 2 O 5 and ZrO 2 .Nb 2 O 5 .
Claim 25
Dependent Claim
20 words
A method according to claim 14, wherein said composition includes at least 75% by weight of electronic conductive oxide ceramics.
Claim 26
Dependent Claim
37 words
The method of claim 14, wherein said electronic conductive oxide ceramic is a composite perovskite structure oxide selected from the group consisting of LaY 1/2 In 1/2 O 3 and LaNi 2/3 Ta 1/3 O 3 .
Claim 27
Dependent Claim
44 words
The method of claim 14, wherein said electronic conductive oxide ceramic is a rutile structure oxide selected from the group consisting of Fe 2 O 3 .Ta 2 O 5 , NiO.Ta 2 O 5 , and SnO 2 .Ta 2 O 5 .
Claim 28
Dependent Claim
20 words
The method of claim 14 wherein said electronic conductive oxide is the columbite structure oxide NiO.Nb 2 O 5 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-11-05 | 1983-05-07 | 1983-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-05 | 1987-05-07 | 1987-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-05 | 1991-05-07 | 1991-11-06 | $7700.00 | Window Closed / Lapsed |