Anode for aluminium electrolysis

Abstract

An anode, in particular an anode for the use in aluminium electrolysis cells, includes an anode body with a first stub hole for the insertion of a stub for the connection with a voltage source. The anode includes at least a first aluminium core and a second aluminium core that are arranged inside the anode body for the connection with the voltage source. A first distance between the first aluminium core and the bottom of the anode is different from a second distance between the second aluminium core and the bottom of the anode.

Claims

1. An anode comprising an anode body with a first stub hole for the insertion of a stub for the connection with a voltage source, the anode comprising at least a first aluminium core and a second aluminium core that are arranged inside the anode body for the connection with the voltage source, wherein a first distance between the first aluminium core and the bottom of the anode is different from a second distance between the second aluminium core and the bottom of the anode.

2. The anode according to claim 1, wherein a length of the first aluminium core is different from a length of the second aluminium core.

3. The anode according to claim 1, wherein the first aluminium core is arranged in a first blind hole of the anode body and the second aluminium core is arranged in a second blind hole of the anode body, wherein the first aluminium core and the second aluminium core are in particular parallel to each other.

4. The anode according to claim 1, wherein the first aluminium core and the second aluminium core are arranged rectangular to the bottom of the anode.

5. The anode according to claim 1, wherein the anode has a cuboid-like shape.

6. The anode according to claim 3, wherein the first blind hole comprising the first aluminium core is sealed by a seal.

7. The anode according to claim 3, wherein an opening of the first blind hole is adjacent to an opening of the first stub hole.

8. The anode according to claim 3, wherein a rotational axis of the first blind hole is parallel to a rotational axis of the first stub hole.

9. The anode according to claim 3, wherein a first notch connects the first stub hole with the first blind hole.

10. The anode according to claim 3, wherein at least a second aluminium core is arranged inside the anode body in a second blind hole.

11. The anode according to claim 10, wherein the first blind hole is longer than the second blind hole.

12. The anode according to claim 10, wherein the first blind hole has a smaller diameter than the second blind hole.

13. The anode according to claim 1, wherein at least one of the following parameters are balanced in order to achieve an optimized current density distribution when used in an aluminium electrolysis process: a diameter of an aluminium core; a length of an aluminium core; an arrangement of the aluminium core in the anode.

14. A method for the manufacture of an anode, in particular for the manufacture of the anode according to claim 1, comprising an anode body with a stub hole for the insertion of a stub for the connection with a voltage source, wherein an aluminium core is arranged inside the anode body for the connection with the voltage source.

15. The anode according to claim 1 for the use in aluminium electrolysis cells.

16. The anode according to claim 6, wherein the seal comprising cast iron.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings used to explain the embodiments show:

(2) FIG. 1a a top view on an example of an anode;

(3) FIG. 1b a sectional view of the FIG. 1a, along the line A-A; and

(4) FIG. 1c a sectional view of the FIG. 1a, along the line B-B.

(5) In the figures, the same components are given the same reference symbols.

PREFERRED EMBODIMENTS

(6) FIG. 1a shows a top view on an example of an anode 1. The anode 1 is box-shaped. The anode 1 has a height of 650 mm, a length of 1625 mm and a width of 780 mm. It comprises three stub holes 20, 21, 22 in a row, having a diameter of 190 mm. The stub (not shown) has a diameter of 160 mm. The cap between the stub and the stub hole is filled with liquid cast iron.

(7) Further, connected by a notch, each stub hole 20, 21, 22 is connected to a blind hole. Stub hole 20 is connected to three blind holes 30, stub hole 21 is connected to four blind holes 31 and stub hole 22 is connected to three blind holes 32.

(8) Each blind hole 30, 31, 32 comprises an enlarged diameter at a top of the anode 1. In a first step, the blind holes 30, 31, 32 are filled with aluminium, in particular with liquid aluminium or with solid aluminium bars. Then, the stubs are arranged in the stub holes 20, 21, 22. The gaps between the stub and the stub holes 20, 21, 22 are then filled with liquid cast iron. The iron flows through the notches into the area of the blind holes 30, 31, 32 with enlarged diameter. Therewith an electric connection between the stub and the aluminium core is established. Further, the blind holes 30, 31, 32 are sealed.

(9) FIG. 1b shows a sectional view of the FIG. 1a, along the line A-A. As can be seen, the length of the blind holes 30.1 and 30.2 are different. The blind hole 30.1 has a distance to the bottom of the anode 1 of L1, while the blind hole 30.2 has a distance to the bottom of the anode 1 of L2. During the consumption of the anode 1, the bottom of the blind hole 30.1 will be reached, wherewith the aluminium core (not shown) will flow out of the hole 30.1. The current will now flow to the second aluminium core in the stub hole 30.2. The distance of the second stub hole 30.2 to the bottom of the electrode will be at this stage L2-L1. Also, the length of the blind holes 31 and the length of the blind holes 32 are different. During the electrolysis process the current will pass mostly to the longest aluminium cores since there is the lowest resistance. The height of the anode 1 is decreasing. First, the tip of the longest blind hole is reached, wherewith the aluminium will pour out of the blind hole. Since the top of the blind hole is sealed, chimney effect can be avoided. Later, the other aluminium cores will be reached to and pour out. Finally, the current will pass by the stub through the remaining part of the anode 1.

(10) FIG. 1c shows a sectional view of the FIG. 1a, along the line B-B. It can be seen, that the blind holes 31 related to the stub hole 21 having three different lengths. They have a length of 500 mm, 400 mm and 300 mm.

(11) In order to achieve an optimized current distribution during the electrolysis process, the number and position of the stub holes, the number and position of the blind holes and the aluminium cores as well as the dimension of the stub holes and the blind holes can be optimized.

(12) However, in other embodiments, the anode 1 can have other shapes known to the skilled in the art. The blind holes can have different diameters. The length of the blind holes can vary. The number of blind holes per stub hole can vary. Also, the number of stub holes in the anode 1 can vary.

(13) In summary, it is to be noted that an anode for the production of aluminium by an electrolysis process is established, wherewith at least in an early stage of the anode life, the voltage drop can be reduced. Further, by adjusting the diameter and length of the blind holes, the current distribution can be influenced.