US3617454A

US3617454A - Bus structure from aluminum reduction cells

Info

Publication number: US3617454A
Application number: US876128A
Authority: US
Inventors: Arthur F Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-11-12
Filing date: 1969-11-12
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02

Abstract

The improvement in electrolytic cells for the reduction of aluminum in which a plurality of cells are electrically connected in a line, the improvement comprising diagonal bus structure for connecting to the cathode collector elements at the upstream side of the cell for directing current therefrom exteriorly of the cell diagonally to the opposite ends.

Description

United States Patent Inventor Arthur F. Johnson 203 Creole Lane, Franklin Lakes, NJ. 07417 Appl. No. 876,128

Filed Nov. 12, 1969 Patented Nov. 2, 1971 BUS STRUCTURE FROM ALUMINUM REDUCTION CELLS 17 Claims, 5 Drawing Figs.

U.S. Cl .L 204/67, 204/243, 204/244 Int. Cl C22d 3/12, C22d 3/02 Field of Search 204/67, 243-247 [56] References Cited UNITED STATES PATENTS 2,999,801 9/1961 Wleugel 204/244 3,063,919 11/1962 Jouguet et a1... 204/244X Primary ExaminerJohn l-l. Mack Assistant Examiner-D. R. Valentine Attorney-Pennie, Edmonds, Morton, Taylor and Adams ABSTRACT: The improvement in electrolytic cells for the reduction of aluminum in which a plurality of cells are electrically connected in a line, the improvement comprising diagonal bus structure for connecting to the cathode collector elements at the upstream side of the cell for directing current therefrom exteriorly of the cell diagonally to the opposite ends.

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INVENTOR. ARTHUR E JOHNSON wax/ 2% ATTORNEYS BACKGROUND OF THE INVENTION In my earlier US. Pat. No. 3,385,778, I disclose a currentcollecting system for an aluminum reduction cell in which the current from the cathode collector elements is collected at each side and each end of the cell and directed to exteriorly disposed bus structure encircling the cell. From there, the current is led to the anode of the next downstream cell disposed in side by side relationship. In the construction disclosed in my earlier patent, the cathode collector elements are divided into four sets. Two of these sets extend normally to the sides of the cell; one set from the upstream side and the other from the downstream side of the cell. The remaining two sets extend inwardly from the opposite two ends of the cell. The current in each of these-sets is led to the exterior bus structure through the walls from which they extend. For example, the collector elements extending inwardly fromthe upstream side of the cell are connected to bus structure disposed exteriorly of the cell along this side. With the cell construction disclosed in my earlier patent, the collection of the current as described above surpresses any electromagnetic stiring of the reduced molten aluminum and lessens the resultingheaping of the aluminum. The most harmful electromagnetic effects are experienced along the upstream side of the cell and particularly at the upstream corn'ers where the vertical magnetic flux is at a maximum. With the invention disclosed in my earlier patent, however, the current paths reduce the vertical magnetic flux at the upstream corners of the cell andthus reduce the currents in the molten aluminum so as to lessen to about half the tendency of the molten aluminum to heap or circulate at these comers of the cell. This improves the operating efficiencies as well as the thermo and electrical efficiencies of the cell.

SUMMARY OF THE INVENTION In accordance with the teachings of the present invention, the concentration of the vertical magnetic flux as well as the electromagnetic circulation and heaping at the upstream corners of the cell are further reduced from that found in the cell construction of my earlier patent. With the cell construction of the present invention, some or all of the current collected by the collector elements at the upstream side of the cell is fed exteriorly underneath the cell in diagonal paths toward the opposite ends of the cell. This, in turn, reduces or eliminates the current flowing around the upstream corners of the cell along exteriorly disposed bus structure. In addition, the collector elements on the upstream side of the cell which are disposed near, one end of the cell are connected to bus structure which is electrically separated from the bus structure for carrying current from the upstream collector elements at the other end of the cell. A similar separation of the bus structure is provided on the downstream side of the cell so that current flow from one cell to the next in the line is from one localized quadrant of the cell to a similarly localized quadrant of the next downstream cell. This construction limits the amount of current to any one anode of the cell and thus suppresses current variations in the individual anodes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top plan view of two cells in side by side relationship with certain parts removed to show the current collecting structure;

FIG. 2 is a vertical, cross section taken along lines 2-2 of FIG. 1 of a fully constructed cell;

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, two electrolytic cells of the Hall type for the electrolytic production of aluminum are shown in side by side electrically connected relationship. For clarity and to avoid a duplication of the structure represented, certain parts of the cells are not shown in FIG. I. In FIG. 2, however, a cross-sectional view of a fully constructed cell is shown. Each cell in the line is comprised of a rectangularshaped, open-topped potshell I having

steel sides

2, 3,

steel ends

4, 5 and steel bottom 6. The bottom and sides of the potshell are insulated with a granular or brick-type refractory 7. A thinner refractory 8 is used for insulating the top deck 9 of the potshell. A carbon potlining 10 holds the cryolite fusion 11 and the underlying layer of molten aluminum I2. Two rows of anode carbons 13 are suspended in the cryolite fusion by anode rods 14 which receive current from an anode bus 15 suspended above the potshell. Steel cathode collector elements 16 are embedded in the carbon potlining for collecting current and directing it outwardly of the potshell to the cathode bus structure generally-designated at 17. Flexible aluminum or copper straps l8 connect the cathode collector elements to the cathode bus structure. The thinner refractory 8 is advantageously used for insulating the collector elements where they extend through the walls of the potshell.

The potshell is supported on pairs of steel channel irons l9 welded or otherwise secured to the opposite sides of steel plates 20 as shown in FIG. 9 of my earlier patent. The channel irons are disposed underneath the potshell and extend outwardly of its sides while the vertical steel plates abut against the sides of the potshell to restrain them from expanding and thus prevent heaving of the potlining. As shown in FIG. 2, the channel irons are supported on a concrete or refractory floor 21 to maintain the potshell raised above the floor. In addition, the floor is channeled at 22 directly underneath the potshell. This support allows cooling air to flow in underneath the potshell and then upwardly around the sides. In addition, this support structure permits positioning of the bus structure in accordance with the teachings of the present invention as more fully described below.

In the embodiment of the invention shown in FIG. I, the cathode collector elements 16 extend generally normal to -the sides of the potshell. One set of side collector elements extends from the upstream side 2 about half way to the downstream side while a second set, separate from the first set, extends from the downstream side 3 about half way to the upstream side. In accordance with the teachings of the present invention, the bus structure for connecting at least some of the side collector elements on the upstream side of the potshell directs the current in a diagonal path underneath the potshell to the

opposite ends

4 and 5 of the shell.

In the embodiment of FIG. 1, two

diagonal buses

23, 24 are provided for connection to the four-side collector elements on the upstream side of the potshell disposed most centrally between the ends of the potshell. The two

collector elements

16a and 16b nearer the end 4 of the potshell are connected to the diagonal bus 23 while the two

collector elements

16a and 16b disposed nearer the end 5 of the potshell are connected to the diagonal bus 24.

The construction of the diagonal bus 23 is most clearly shown in FIG. 3 as comprising an elongated central section having upstanding portions at either end. At one end. there are two upstanding portions 23a and 231) while at the other end there is a single upstanding portion 23c. The

portions

23a and 23!: are adapted to be connected to the collector elements and 16b, respectively, at the point where they extend through the upstream side 2 of the potshell. The upstanding portion 23c is adapted to be connected to the bus structure at the downstream comer of the potshell for directing current to the anode of the next downstream cell. The diagonal busses 23 and 24 are mirror images of each other.

In FIG. 2, the buss structure 24 is shown as extending exteriorly of the potshell from the upstream side 2, underneath the bottom 6 of the potshell to the end (hidden from view) where it is connected by the upstanding portion 24c to the external bus structure leading to the next downstream cell. The channel 22 in the refractory floor 21 provides room for the extension of the diagonal busses underneath the potshell.

The side-collector elements on the upstream side of the potshell which are not connected to the diagonal buses are connected to cathode buses 25-30. More particularly, the side-

collector elements

16c and 16d are connected to the bus 25, the

collector elements

16c and 16f to the bus 26, and the collector elements 16 16h, and 16i are connected to the bus 27. Similarly, the. collector elements l6a-16i' nearer the other end 5 of the potshell are connected to the

buses

28, 29 and 30.

The

bus structure

25, 26 and 27 is electrically separate from the

bus structure

28, 29 and 30. The bus structure 25-27 extends around the end 4 of the potshell toward the next cell in the potline while the bus structure 28-30 extends around the end Sin a similar fashion.

To complete the electrical connection of the collector elements to the external bus structure, the collector elements extending inwardly of the potshell from the downstream side 3 are connected to downstream cathode buses 31-34. With reference to FIG. I, the collector elements l6j, 16k, 161 and 16m are connected to the bus 31 while the collector elements l6n, I60, 16p, 16g and 16r are connected to the bus 32. Similarly, the collector elements 16j'-l6r' are connected in the busses 33 and 34. As with the upstream bus structure, the

buses

31 and 32 are electrically separate from the buses 33 and 34. The downstream bus structure joins the upstream bus structure at the downstream corners of the potshell. From there, all bus structure is directed to the anode structure of the next downstream cell to maintain the electrical connection between the cells.

In order to limit the flow of current from one quadrant of the upstream cell to. a similar quadrant of the downstream cell, the anode structure is brokeninto four separate sections and the cathode bus from each quadrant of the cell 1 is connected to the section of the anode structure 15 disposed over the corresponding quadrant of the next downstream cell. The quadrant separation of the bus structure of the cells together with the diagonal orientation of the

buses

23 and 24 limits the amount of current flowing around the upstream corners of each cell and thus suppresses the magnetic activity at these corners tending to cause heaping of the molten aluminum.

The diagonally disposed paths defined by the

buses

23 and 24 together with the associated buses 25-27 and 28-30 define triangular areas at each upstream corner of the potshell. Accordingly, the current being directed along the

diagonal buses

23 and 24 produces within the triangular area at each corner of the potshell a vertical flux in opposition to the flux created by the current flowing through the buses 25-27 and 28-30.

In addition to the limitations ofthe current flow at the upstream corners of the potshell, the diagonal bus structure and separation of the buses generally improve the operating effi- .-.....-..M.........1... Wswe cciency of the potshell by improving the ampere efficiency. This improvement results because the current variations in each individual anode of the anode bus structure is suppressed by dividing the anode bus structureinto sections and thus limiting the current which is made available to each anode. With conventional cells where the bus structure encircles the potshell, current variations in the individual anodes may vary to a greater extent and thus decrease the ampere deficiency of the cell. This variation may occur, for example, when the anodes are new and set too low at one end of the cell. This would cause all available current to be drawn from the cathode bus disposed at the same end of the adjacent upstream cell. In addition, however, current would also be drawn from the cathode bus at the opposite end of the adjacent upnec ted togetherYAsaconsequenceigreater than one-fourth of the total amperage can be drawn around either of the upstream comers of the cell resulting in intense magnetic activity, in turn, causing heaping bf the molten aluminum.

A modified construction of the present invention is shown in FIG. 4. There, the orientation of the side-collector elements is the same as in the construction shown in FIG. 1. Instead of the single pair of diagonal underpot buses, however, a

second pair

39, 40 is provided. These two

additional buses

39 and 40 are connected, respectively, to the

upstream collector elements

16c and 16d and and 16d. With this construction, more of the current collected by the side-collector elements on the upstream side of the potshell may be directed diagonally to the opposite ends of the potshell; and thus the current flowing around the upstream comers of the potshell is further reduced.

In FIG. 5, there is shown a construction in which all of the current collected along the upstream side of the potshell is directed diagonally to the opposite ends of the potshell. In this construction, only six centrally disposed side-collector elements l6a-l6c, l6a-l6c, l6j-l6l and 16j'-l6l' extend inwardly from the sides of the potshell. The three collector elements l6a-l6c on the upstream side nearer the end 4 of the potshell are connected to one diagonally extending underpot bus while the three collector elements l6a-l6c' nearer the end 5 are connected to a separate diagonal bus 42 extending toward that end of the potshell. For this purpose, each of the

buses

41 and 42 has three upstanding portions designated by the suffix a, b and c, at the upstream side of the potshell. To connect these buses to the bus structure at the downstream corners of the potshell, the upstanding portions 41d and 42d are provided.

In the construction shown in FIG. 5, a plurality of

end collector elements

44, 45 are provided in place of the upstream side collector elements 1611-16! and I6d'-l6i' and the downstream side-collector elements 16m-16r and 16m '-l6r' found in the embodiment of FIG. 1. These

end collector elements

44 and 45 extend inwardly from either end of the potshell and are connected directly to end

bus elements

46, 47 and 48, 49. The latter bus elements replace the bus elements 25-27 and 28-30 of the construction shown'in FIG. 1. It will be seen that with the construction of FIG. 5, all current flow around the upstream corners of the potshell is eliminated. Accordingly, electromagnetic stiring and thus circulation and heaping of the molten aluminum at these upstream corners are greatly reduced.

The above description of the present invention has been made with respect to the preferred embodiments thereof. However, it is to be understood that various changes may be made without departing from the scope of the invention as set forth in the following claims.

I claim:

1. In an electrolytic cell for the reduction of aluminum having a rectangular potshell adapted to be disposed in a line of electrolytic cells in electrically connected side by side relationship and having an electrically conductive cathode potlining and a plurality of side-cathode collector elements extending generally normal to the sides of the potshell and in electrical engagement with said potlining, and a current carrying bus structure disposed cxteriorly of said potshell. for carrying current from its cathode collector elements to the anode of the next downstream cell in said line of cells, the improvement wherein said bus structure includes an underpot bus section connected on the upstream side of said potshell to the side collector elements disposed centrally of the ends of said potshell and extending diagonally underneath said potshell to the opposite ends thereof for connection to the anode of the next downstream cell.

2. The improvement in an electrolytic cell according to claim 1 wherein the underpot bus section includes two separate buses, each of which extends diagonally underneath the potshell to one of the opposite ends thereof.

3. The improvement in an electrolytic cell according to claim 2 wherein each of the diagonal buses are connected on the upstream side of the potshell to a plurality of said side-collector elements disposed adjacent a different end of the potshell.

4. The improvement in an electrolytic cell according to claim 3 wherein the collector elements extending normal to the sides of the potshell include one set extending from the upstream side thereof toward the downstream side and of which at least some are connected to said diagonal buses; and a second set, separate from the first set, extending from the downstream side of said potshell toward the upstream side.

5. The improvement in an electrolytic cell according to claim 4 wherein the collector elements of the second set are connected to a downstream bus extending externally of said potshell on the downstream side thereof.

6. The improvement in an electrolytic cell according to claim 5 wherein a plurality of parallel extending diagonal buses are disposed underneath said potshell for connecting to the side-collector elements on the upstream side of said potshell.

7. The improvement in an electrolytic cell according to claim 5 wherein said bus structure includes exteriorly disposed end buses disposed along the ends of the potshell and end-collector elements extending from and normal to each of said ends to a point less than half the length of said potshell, said end-collector elements at each end of the potshell being connected to the end bus at that end.

8. The improvement in an electrolytic cell according to claim 7 wherein all of the side-collector elements of said one set are connected to said diagonal buses.

9. The improvement in an electrolytic cell according to claim 5 wherein the downstream bus includes two sections each of which extends from one of the forward corners toward each other with one section being connected to the collector elements of the second set disposed adjacent one end of the potshell and the other section being connected to the collector elements disposed adjacent the other end of the potshell.

10. The improvement in an electrolytic cell according to claim 9 wherein the downstream bus and diagonal buses are joined at the downstream corners of the potshell for leading to the next downstream cell in said line.

ll. In the process of electrolytically reducing aluminum in a rectangular potshell adapted to be disposed in a line of electrolytic cells in electrically connected side by side relationship and having an electrically conductive cathode potlining and a plurality of side cathode collector elements extending generally normal to the sides of the potshell and in electrical engagement with said potlining, and a current carrying bus structure disposed exteriorly of said potshell and connected to said side collector elements for carrying current from said collector elements to the anode of the next downstream cell in said line of cells, the improvement of collecting current from the plurality of said collector elements at the upstream side of said potshell and directing said current exteriorly below said potshell along diagonal paths to the opposite ends thereof for feeding to the anode of the next downstream cell.

12. The improvement in the process according to claim 11 wherein the current in the side collector elements nearer one end of said potshell is directed along one of said diagonal paths to the one end of said potshell and the current in the collector elements nearer the other end is directed in a second diagonal path to the other end of said potshell.

13. in the process according to claim 12 wherein the collector elements extending normal to the sides of the potshell include one set extending from the upstream side thereof toward the downstream side and a second set, separate from said first set, extending from the downstream side toward the upstream side, the improvement wherein the current in a plurality of collector elements of said first set is collected at the upstream side of said potshell'and directed along said diagonal paths and the current in the collector elements of said second set is collected at the downstream side of said potshell and directed exteriorly of said potshell along the downstream side thereof for feedin to the anode of the next downstream cell in said line.

14. n the process according to claim 13 wherein end-collector elements extend from and normal to each of the ends of said potshell to a point less than half the length thereof. the improvement wherein the current in the end collector elements at each end of the potshell is connected at that end and directed exteriorly of said potshell along that end for feeding to the anode of the next downstream cell in said line.

15. The improvement in the process according to claim 14 wherein the current in all of the collector elements of said one set is collected at the upstream side of said potshell and fed exteriorly along said diagonal paths to the ends of said potshell.

16. The improvement in the process according to claim 13 wherein the current in the collector elements of said second set nearer one end of said potshell is directed separately of the current in the collector elements of the second set nearer the other end of the potshell to the anode of the next downstream cell.

17. The improvement in the process according to claim 16 wherein the current collected in each quadrant of said potshell is fed to the corresponding quadrant of the next downstream cell.

Claims

2. The improvement in an electrolytic cell according to claim 1 wherein the underpot bus section includes two separate buses, each of which extends diagonally underneath the potshell to one of the opposite ends thereof.
3. The improvement in an electrolytic cell according to claim 2 wherein each of the diagonal buses are connected on the upstream side of the potshell to a plurality of said side-collector elements disposed adjacent a different end of the potshell.
4. The improvement in an electrolytic cell according to claim 3 wherein the collector elements extending normal to the sides of the potshell include one set extending from the upstream side thereof toward the downstream side and of which at least some are connected to said diagonal buses; and a second set, separate from the first set, extending from the downstream side of said potshell toward the upstream side.
5. The improvement in an electrolytic cell according to claim 4 wherein the collector elements of the second set are connected to a downstream bus extending externally of said potshell on the downstream side thereof.
6. The improvement in an electrolytic cell according to claim 5 wherein a plurality of parallel extending diagonal buses are disposed underneath said potshell for connecting to the side-collector elements on the upstream side of said potshell.
7. The improvement in an electrolytic cell according to claim 5 wherein said bus structure includes exteriorly disposed end buses disposed along the ends of the potshell and end-collector elements extending from and normal to each of said ends to a point less than half the length of said potshell, said end-collector elements at each end of the potshell being connected to the end bus at that end.
8. The improvement in an electrolytic cell according to claim 7 wherein all of the side-collector elements of said one set are connected to said diagonal buses.
9. The improvement in an electrolytic cell according to claim 5 wherein the downstream bus includes two sections each of which extends from one of the forward corners toward each other with one section being connected to the collector elements of the second set disposed adjacent one end of the potshell and the other section being connected to the collector elements disposed adjacent the other end of the potshell.
10. The improvement in an electrolytic cell according to claim 9 wherein the downstream bus and diagonal buses are joined at the downstream corners of the potshell for leading to the next downstream cell in said Line.
11. In the process of electrolytically reducing aluminum in a rectangular potshell adapted to be disposed in a line of electrolytic cells in electrically connected side by side relationship and having an electrically conductive cathode potlining and a plurality of side cathode collector elements extending generally normal to the sides of the potshell and in electrical engagement with said potlining, and a current carrying bus structure disposed exteriorly of said potshell and connected to said side collector elements for carrying current from said collector elements to the anode of the next downstream cell in said line of cells, the improvement of collecting current from the plurality of said collector elements at the upstream side of said potshell and directing said current exteriorly below said potshell along diagonal paths to the opposite ends thereof for feeding to the anode of the next downstream cell.
12. The improvement in the process according to claim 11 wherein the current in the side collector elements nearer one end of said potshell is directed along one of said diagonal paths to the one end of said potshell and the current in the collector elements nearer the other end is directed in a second diagonal path to the other end of said potshell.
13. In the process according to claim 12 wherein the collector elements extending normal to the sides of the potshell include one set extending from the upstream side thereof toward the downstream side and a second set, separate from said first set, extending from the downstream side toward the upstream side, the improvement wherein the current in a plurality of collector elements of said first set is collected at the upstream side of said potshell and directed along said diagonal paths and the current in the collector elements of said second set is collected at the downstream side of said potshell and directed exteriorly of said potshell along the downstream side thereof for feeding to the anode of the next downstream cell in said line.
14. In the process according to claim 13 wherein end-collector elements extend from and normal to each of the ends of said potshell to a point less than half the length thereof, the improvement wherein the current in the end collector elements at each end of the potshell is connected at that end and directed exteriorly of said potshell along that end for feeding to the anode of the next downstream cell in said line.
15. The improvement in the process according to claim 14 wherein the current in all of the collector elements of said one set is collected at the upstream side of said potshell and fed exteriorly along said diagonal paths to the ends of said potshell.
16. The improvement in the process according to claim 13 wherein the current in the collector elements of said second set nearer one end of said potshell is directed separately of the current in the collector elements of the second set nearer the other end of the potshell to the anode of the next downstream cell.
17. The improvement in the process according to claim 16 wherein the current collected in each quadrant of said potshell is fed to the corresponding quadrant of the next downstream cell.