Electrodes useful for molten salt electrolysis of aluminum oxide to aluminum
View Patent ↗The present invention provides a method of making a carbon electrode, suitable for use as an anode in an aluminum reduction cell, which comprises mixing an aggregate, comprising a mixture of particulate shot coke, and a particulate carbonaceous material other than shot coke with coal tar pitch or petroleum pitch or a combination of these pitches at an elevated temperature to form a paste wherein said aggregate comprises a combination of butts, coarse, and fine particles and said particulate shot coke may comprise a majority of said coarse particles or fine particles, and said paste comprises from about 80 to about 90%, by weight, of said aggregate and from about 10 to about 20%, by weight, of said pitch; forming said paste into a solid body; and baking said solid body at an elevated temperature to form said carbon electrode.
1. A method of making a carbon electrode, suitable for use as an anode in an aluminum reduction cell, which comprises mixing an aggregate of different size fractions, comprising a mixture of particulate shot coke and a particulate carbonaceous material other than shot coke with coal tar pitch or combination pitch at an elevated temperature to form a paste, and said paste comprises from about 80 to about 90%, by weight, of said aggregate and from about 10 to about 20%, by weight, of said coal tar pitch or combination pitch wherein said aggregate comprises from about 5 to 90%, by weight, shot coke; forming said paste into a solid body; and baking said solid body at an elevated temperature to form said carbon electrode.
2. The method of claim 1 wherein said shot coke comprises from about 10 to 50%, by weight, of said aggregate.
3. The method of claim 1 wherein said carbonaceous material is selected from the group consisting of sponge, and coal tar pitch cokes, and recycled carbon anode remnants or butts.
4. The method of claim 1 wherein said aggregate wherein said aggregate comprises from about 5 to 60% of coarse particles, 10 to 50% fine particles and from 0 to 30% butts.
5. The method of claim 4 wherein said coarse particles comprise from 25 to 75%, by weight, of shot coke.
6. The method of claim 4 wherein said fine particles comprise from 25 to 75%, by weight of shot coke.
7. The method of claim 1 wherein said solid body is subject to compressing or vibrating to form a green anode prior to baking.
8. The method of claim 1 wherein said solid body is baked at a temperature of above 1000° Centigrade.
9. A method of making a carbon anode for use in an aluminum reduction cell, in which aluminum oxide is reduced to molten aluminum metal at an elevated temperature, which comprises:
(a) mixing an aggregate comprising a mixture of particulate shot coke, prepared by screening and milling to provide a particulate mixture comprising at least 10%, by weight and a particulate carbonaceous material other than shot coke, and recycled carbon anode remnants or butts, with coal tar or combination pitches at an elevated temperature to form a paste wherein said aggregate comprises a combination of coarse, and fine particles and said particulate shot coke comprises a majority of said coarse particles, and said paste comprises from about 80 to about 90%, by weight, of said aggregate and from about 10 to about 20%, by weight, of said coal tar or combination pitches;
(b) forming said paste into a solid body; (c) subjecting said solid body to compression or vibration to form a green anode; and (d) baking said green anode at an elevated temperature of greater then 1000° Centigrade to form said carbon electrode.
10. The product of claim 1 .
11. The product of claim 9 .
12. A carbon electrode, suitable for use as an anode in an aluminum reduction cell, which comprises (a) an aggregate comprising a mixture of particulate shot coke and a particulate carbonaceous material other than shot coke, and (b) a coal tar pitch or combination pitch binder, wherein said aggregate comprises a combination of butts, coarse, and fine particles and said particulate shot coke comprises a majority of said fine particulates.
13. A method for producing aluminum by the molten salt electrolysis of aluminum oxide which comprises electrolyzing aluminum oxide dissolved in a molten salt at an elevated temperature by passing a direct current through an anode to a cathode disposed in said molten salt wherein said anode is the product of claim 1 .
14. A method of making a carbon electrode, suitable for use as an anode in an aluminum reduction cell, which comprises mixing an aggregate, comprising a mixture of particulate shot coke, and a particulate carbonaceous material other than shot coke with coal tar pitch or combination pitch at an elevated temperature to form a paste wherein said aggregate comprises a combination of butts, coarse and fine particles wherein said particulate shot coke comprises more than 5%, by weight, of said aggregate, and said paste comprises from about 80 to about 90%, by weight, of said aggregate and from about 10 to about 20%, by weight, of said coal tar pitch or combination pitch; forming said paste into a solid body; and baking said solid body at an elevated temperature to form said carbon electrode.