Alumina reduction cell and improved anode system therein

Claim 2

In an alumina reduction cell having a bath of molten electrolyte containing dissolved alumina, a crust of solidified electrolyte overlying the bath and means for passing electric current through the bath, the improvement comprising: a. a continuous anode having a plurality of tubular passageways extending downwardly through the anode at spaced locations within its transverse cross-section; b. means for breaking an opening through any crust formed in said passageways at their lower outlet ends adjacent the anode working surface; and c. means for introducing alumina into the bath through said passageways.

Claim 3

Apparatus according to claim 1 including means for collecting gases evolved from the cell through said anode passageways.

Claim 4

Apparatus according to claim 2 in which said passageways are so disposed that no point on the outer periphery of the anode working surface is further removed from the nearest passageway outlet than three-fourths the anode width.

Claim 5

Apparatus according to claim 1 including an anode having passageways which are spaced lengthwise of the cell.

Claim 6

Apparatus according to claim 4 having anode passageways spaced lengthwise of the cell along its centerline.

Claim 7

Apparatus according to claim 4 in which said anode is longer lengthwise of the cell than its width across the cell.

Claim 8

Apparatus according to claim 1 in which said passageways are so disposed that every point on the anode working surface is no further removed from the nearest passageway outlet than three-fourths the anode width.

Claim 9

Apparatus according to claim 1 in which the aggregate anode cross-sectional area constitutes more than 50 percent of the floor area occupied by the cell.

Claim 10

Apparatus according to claim 1 in which said anode comprises carbonaceous blocks which are baked prior to installation to eliminate substantially all hydrocarbon fumes and to develop sufficient structural strength to support themselves in service in the anode.

Claim 11

Apparatus according to claim 9 in which said carbonaceous blocks are baked at a temperature between 400* and 600* C.

Claim 12

Apparatus according to claim 10 in which electrical contact pins are inserted in the anode blocks before baking.

Claim 13

In an alumina reduction cell having a bath of molten electrolyte containing dissolved alumina, a self-baking carbon anode including a baked lower portion adjacent the bath and a softer upper portion, and a crust of solidified electrolyte overlying the bath, the improvement comprising: a. tubular casing means in at least said upper portion of the anode to provide interior passageways extending downwardly through the anode; and b. plunger means operable inwardly of said passageways to prevent obstructions therein due to crust formations at the lower outlet ends thereof adjacent the anode working surface.

Claim 14

In an alumina reduction cell having a bath of molten electrolyte containing dissolved alumina, a self-baking carbon anode including a baked lower portion adjacent the bath and a softer upper portion, and a crust of solidified electrolyte overlying the bath, the improvement comprising: a. tubular casing means in at least said upper portion of the anode to provide interior passageways extending downwardly through the anode; and b. plunger means operable inwardly of said passageways to prevent obstructions therein due to crust formations at the lower outlet ends thereof adjacent the anode working surface.

Claim 15

Apparatus according to claim 12 including feeder means for introducing alumina into the anode passageways, said plunger means being arranged for movement between a lower position to produce an access opening through any crust Formed at said lower outlet end of each anode passageway and an upper position allowing alumina to flow into the bath through said access opening.

Claim 16

Apparatus according to claim 12 in which said passageways and associated plunger means are so disposed that no point on the outer periphery of the anode working surface is farther removed from the nearest access opening than three-fourths the anode width.

Claim 17

Apparatus according to claim 14 including means for collecting gases evolved from the cell through said passageways.

Claim 18

In the operation of an alumina reduction cell having an anode, a bath of molten electrolyte containing dissolved alumina and a crust of solidified electrolyte overlying the bath, the method which comprises: providing a continuous anode having a plurality of interior passageways extending downwardly through the anode, said passageways having their lower outlet ends disposed adjacent the anode working surface; feeding alumina into the bath through said passageways; maintaining a blanket of alumina and supporting crust around the anode to provide a substantially gas-tight cover over the bath as said feeding proceeds; breaking an opening through any crust formed within said passageways at the lower outlet ends thereof; and collecting gases evolved from the cell through said passageways, whereby said feeding and gas collecting operations are carried out without disrupting the main body of said crust outwardly of the anode.

Claim 19

In the operation of an alumina reduction cell having an anode, a bath of molten electrolyte containing dissolved alumina and a crust of solidified electrolyte overlying the bath, the method which comprises: providing a continuous anode having a plurality of interior passageways extending downwardly through the anode, said passageways having their lower outlet ends disposed adjacent the anode working surface; feeding alumina into the bath through said passageways; maintaining a blanket of alumina and supporting crust around the anode to provide a substantially gas-tight cover over the bath as said feeding proceeds; breaking an opening through any crust formed within said passageways at the lower outlet ends thereof; and collecting gases evolved from the cell through said passageways, whereby said feeding and gas collecting operations are carried out without disrupting the main body of said crust outwardly of the anode.

Claim 20

The method of claim 16 which includes providing access openings through the crust at spaced locations outwardly of the anode, said openings being spaced apart sufficiently to preserve the integrity of the crust between openings; and collecting gases evolved from the cell through said openings in the crust.

Claim 21

The method of claim 16 which includes providing a continuous anode in which said passageways are so disposed that no point on the outer periphery of the anode working surface is farther removed from the nearest passageway outlet than three-fourths the anode width.

Claim 22

The method of claim 16 which includes providing a continuous anode having passageways which are spaced lengthwise of the cell.

Claim 23

The method of claim 16 which includes providing a continuous anode which is longer lengthwise of the cell than its width across the cell.

Claim 24

The method of claim 16 which includes providing a continuous anode in which said passageways are so disposed that every point on the anode working surface is no farther removed from the nearest passageway outlet than three-fourths the anode width.

Claim 25

The method of claim 16 in which said feeding comprises passing alumina into the bath from the lower outlet end of one or more of said passageways but includes repeated feeding at spaced locations.

Claim 26

The method of claim 22 in which said feeding occurs at intervals and in amounts sufficient substantially to compensate for depletion of alumina from the bath.