WO2023035063A1

WO2023035063A1 - An electrode body of an electrode for the electrolytic production of a metal

Info

Publication number: WO2023035063A1
Application number: PCT/CA2022/051333
Authority: WO
Inventors: Charles SHANTA; David Prince; Larry MICKELSON
Original assignee: Elysis Limited Partnership
Priority date: 2021-09-07
Filing date: 2022-09-06
Publication date: 2023-03-16
Also published as: AU2022343028A1; CN117337343A; CA3216073A1

Abstract

It is disclosed an electrode body for the electrolytic production of a metal comprising a first portion for operatively connecting the electrode body to an electrolytic cell; a second portion, opposite the first portion; and a middle portion extending between the first and second portions. The body has a continuous external surface forming a round transition between the second and middle portions. The external surface of the middle portion comprises two opposite outer flat surfaces for facing surfaces of adjacent electrodes when the electrode is plunged into an electrolytic bath of the electrolytic cell comprising said adjacent electrodes. Preferably, the electrode is an anode and the anode body has a bore shape with a continuous external surface of the body wall. Preferably, the electrode body is made from a metal alloy, a ceramic or cermet material to form an inert or oxygen-evolving anode used for an eco-friendly production of aluminum.

Description

An electrode body of an electrode for the electrolytic production of a metal

Cross-Reference to Related Applications

[0001] The present patent application claims the benefits of priority of U.S. Provisional Patent Application No. 63/241,258 entitled “ELECTRODE BODY”, and filed at the United States Patent and Trademark Office on September 7, 2021, the content of which is incorporated herein by reference.

Field of the invention

[0002] The present invention generally relates to an electrode body of an electrode, an electrode comprising the same, and an electrolytic cell comprising the electrode(s) for the production of a metal, such as for instance aluminum. In particular, the electrode body is used for the making of an inert or oxygen-evolving anode.

Background

[0003] Aluminum metal, also called aluminium, is produced by electrolysis of alumina, also known as aluminium oxide (IUPAC), in an electrolytic bath of molten electrolyte at about 750 - 1000°C contained in a number of electrolytic cells. The cells have a crucible comprising a steel shell, containing a carbonaceous cathode material, steel current conducting bars and refractory insulation materials capable of containing the electrolyte, at least one cathode and at least one anode.

[0004] The direct current that passes through the anodes, the electrolyte and cathodes causes alumina redox reactions, and is also capable of maintaining the electrolyte bath at the target operating temperature by the Joule effect. The electrolysis cell is regularly supplied with alumina so as to compensate for consumption of alumina caused by electrolysis reactions.

[0005] In the traditional Hall-Heroult process, the anodes are made of carbon and are consumed during the electrolytic reaction. The anodes need to be replaced after 3 to 4 weeks. Consumption of the carbonaceous material releases large quantities of carbon dioxide in the atmosphere.

[0006] Aluminum producers have been searching for anodes made of non-consumable materials, called "inert anodes" or “oxygen evolving anodes”, for several decades, to avoid environmental problems and costs associated with manufacturing and use of anodes made of carbonaceous material. Several materials have been proposed, particularly ceramic materials (such as SnCh and ferrites), metallic materials and composite materials such as materials known as "cermets" containing a ceramic phase and a metallic phase, particularly nickel ferrites containing a metallic copper-based phase.

[0007] Known in the art are anode cylinders or flat plates.

[0008] A recently developed electrolytic cell for the production of aluminum or other metals may comprise alternating rows of inert anodes and wettable inert cathodes, immersed in a molten salt bath with sufficient ionic conductivity to pass current. For instance, one may refer to WO 2017/165838 Al (Xinghua Liu), the content of which is incorporated herein by reference. The molten salt bath has the capacity to dissolve a compound of the metal to be reduced (e.g. a metal oxide, chloride, carbonate, etc.). Gas, such as oxygen, chlorine or carbon dioxide, is produced on the anodes and exits the cell as an offgas. Liquid metal is produced on the cathodes and runs down in a thin film by gravity into a pool or sump for collection.

[0009] When the anodes and cathodes are vertically oriented, they are separated by a distance, known as the anode-cathode distance or ACD. The electrodes also define an overlapping dimension, known as anode-cathode overlap or ACO. When the anode body has a different geometry than the adjacent cathodes, for instance for a cylindrical anode adjacent a cathode plate, the ACD may then vary. Furthermore, the shape and size of inert anodes is related to the desired cell resistance, current density, cathode plate dimensions and cell dimensions. Anodes may be complex to manufacture, in particular when the anode body is made from materials such as a cermet or ceramic for the making of an inert / oxygen evolving anodes.

[0010] There is thus a need for a new electrode shape of an electrolytic cell that allows increasing electrolysis life while providing a more constant ACD.

Summary

[0011] The shortcomings of the prior art are generally mitigated by new anode shapes of an electrolytic cell typically used for the electrolytic production of aluminum.

[0012] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0013] The invention is directed to an electrode body of an electrode for the electrolytic production of a metal, the electrode body extending longitudinally along an axis Z and comprising: a first portion configured for operatively connecting the electrode body to an electrolytic cell; a second portion, opposite the first portion; and a middle portion extending between the first and second portions; wherein the electrode body has a continuous external surface forming a round transition between the second and middle portions, and wherein the continuous external surface of the middle portion defines two opposite outer flat surfaces for facing surfaces of adjacent electrodes when the electrode is plunged into an electrolytic bath of the electrolytic cell comprising said adjacent electrodes.

[0014] According to a preferred embodiment, the electrode body as disclosed herein, may further comprise a longitudinal inner hole extending from the first portion and configured for receiving, at least in part, an electrode pin for operatively connecting the electrode body to an electric power supply when the electrode pin is installed therein, the longitudinal inner hole and the electrode body then defining a body wall around the longitudinal inner hole.

[0015] According to a preferred embodiment, the longitudinal inner hole may define a non-uniform cross-sectional area between the first and second portions of the electrode body. More preferably, the non-uniform cross-sectional area of the inner hole adjacent the first portion may be larger than the non-uniform cross-sectional area adjacent the middle and/or second portions.

[0016] According to a preferred embodiment, the non-uniform cross-sectional area of the inner hole adjacent the first portion has a first geometry that is different than a second geometry of the non-uniform cross-sectional area adjacent the second portion. More preferably, the first geometry defines a circular cross-sectional area whereas the second geometry defines a rectangular cross-sectional area.

[0017] According to a preferred embodiment, the second portion of the electrode body is closed, the body wall defined by the second and middle portions may thus have a uniform or nearly uniform thickness.

[0018] According to a preferred embodiment, the second portion of the electrode body is closed, the body wall defined by the second portion may therefore have a first thickness superior to a second thickness of the body wall defined by the middle portion.

[0019] According to a preferred embodiment, the second portion of the electrode body may have an oval -like shape or a rectangle-like shape with round comers.

[0020] According to a preferred embodiment, the first portion of the body wall may have a circular or oval shape.

[0021] According to a preferred embodiment, the outer flat surfaces may be configured to extend from the second portion to the first portion according to an angle a with the longitudinal axis Z of about 0° such as to be parallel to a plane formed by the adjacent electrodes’ surfaces and provide a constant distance between the middle portion of the electrode body and adjacent electrodes.

[0022] According to a preferred embodiment, the outer flat surfaces may be configured to inwardly extend from the second portion to the first portion according to an angle a with the longitudinal axis Z of between 0,5° and 5°.

[0023] According to a preferred embodiment, the middle portion of the body wall may also comprise two opposite outer lateral surfaces connecting the two opposite outer flat surfaces, the outer lateral surfaces forming a round shaped transition between the two opposite outer flat surfaces of the electrode body. Preferably, the outer lateral surfaces extends inwardly from the second portion to the first portion. More preferably, each of the two inwardly extending opposite outer lateral surfaces defines a shouldershaped transition along the longitudinal axis Z between the middle portion and the first portion.

[0024] According to a preferred embodiment, the electrode body as disclosed herein may further comprise a failsafe system adjacent the first portion to mechanically connect the electrode body to the refractory package. Preferably, the failsafe system may comprise an external groove in the electrode body around and adjacent the first portion.

[0025] According to a preferred embodiment, the electrode is an anode, and the electrode body is an anode body made from a metal or alloy thereof, a ceramic or a cermet material to form an inert or oxygen-evolving anode.

[0026] The invention is also directed to an electrode comprising the electrode body as defined herein and an electrode pin inserted into the electrode body. Preferably, the electrode is for use for the making of a metal, such as aluminum.

[0027] Advantageously, an electrode body with round fillets (no sharp comers) for the transition between the second and middle portions allows reducing stress concentrators and avoiding crack initiation, compared to a electrode plate.

[0028] Despite the round fillets, the electrode body as disclosed herein also comprises opposites flat surfaces for facing adjacent electrodes in the cell, providing as such a more constant ACD compared to a cylindrical anode.

[0029] Other and further aspects and advantages of the present invention will be better understood upon the reading of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

Brief Description of the Drawings

[0030] The above and other aspects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which:

[0031] Figure 1 is a three-dimensional illustration of an electrode body in accordance of a first preferred embodiment;

[0032] Figure 2 is a side view of the electrode body illustrated on Figure 1;

[0033] Figure 3 is a cut view of the electrode body of Figure 2 along line A-A;

[0034] Figure 4a is a top view of the electrode body illustrated on Figure 1;

[0035] Figure 4b is the detailed view of the section B of the electrode body illustrated on Figure 4a;

[0036] Figure 5 is a cut view of the electrode body of Figure 4a along line G-G;

[0037] Figure 6 is the detailed view of the section C of the electrode body illustrated on Figure 3;

[0038] Figure 7 is a three-dimensional illustration of an electrode body in accordance of a second preferred embodiment;

[0039] Figure 8 is a side view of the electrode body illustrated on Figure 7;

[0040] Figure 9 is a cut view of the electrode body of Figure 10a along line A-A;

[0041] Figure 10a is atop view of the electrode body illustrated on Figure 7;

[0042] Figure 10b is the detailed view of the section D of the electrode body illustrated on Figure 10a;

[0043] Figure 11 is a cut view of the electrode body of Figure 10a along line B-B; and

[0044] Figure 12 is the detailed view of the section E of the electrode body illustrated on Figure 11.

Detailed Description of the Preferred Embodiment

[0045] A novel electrode body will be described hereinafter. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby.

[0046] The terminology used herein is in accordance with definitions set out below.

[0047] By "about", it is meant that the value of weight % (wt.%), time, resistance, volume or temperature can vary within a certain range depending on the margin of error of the method or device used to evaluate such weight %, time, resistance, volume or temperature. A margin of error of 10% is generally accepted.

[0048] The description which follows, and the embodiments described therein are provided by way of illustration of an example of particular embodiments of principles and aspects of the present invention. These examples are provided for the purposes of explanation and not of limitation, of those principles of the invention. In the description that follows, like parts and/or steps are marked throughout the specification and the drawing with the same respective reference numerals.

[0049] As aforesaid, the invention is first directed to an electrode body extending longitudinally along an axis Z and comprising a first portion configured for operatively connecting the electrode body to an electrolytic cell; a second portion, opposite the first portion; and a middle portion extending between the first and second portions. The electrode body has a continuous external surface forming a round transition between the second and middle portions. Also, the continuous external surface of the middle portion defines two opposite outer flat surfaces for facing surfaces of adjacent electrodes when the electrode is plunged into an electrolytic bath of an electrolytic cell comprising the adjacent electrodes.

[0050] In the description below of preferred embodiments, the invention is described as an anode body. Of course, similar embodiments can apply to a cathode body.

[0051] Cathodes of an electrolytic cell for the making of a metal, are electrically conductive, chemically resistant to metal and bath, and have good wettability for the produced metal. Cathodes may be for instance vertical plates of a given thickness presenting therefore two opposite flat surfaces for facing the adjacent anodes.

[0052] Figures 1 to 6 show a first embodiment and figures 7 to 12 show a second embodiment of an anode body of an anode for the electrolytic production of a metal. Reference numerals of the drawings in the 100 series identify the first embodiment whereas the reference numerals in the 200 series identify the second embodiment.

[0053] An anode as described herein preferably comprise an anode body in which is inserted an anode pin for conducting the electricity. Examples are provided in U.S. patent US 9,945,041 B2 (Reed et al.), the content of which is incorporated herein by reference.

[0054] According to the preferred embodiment shown in the drawings, the anode body 100, 200 comprises a longitudinal inner hole 110, 210 configured for receiving, at least in part, an anode pin (not illustrated) for operatively connecting the anode body to an electric power supply (not illustrated) when the anode pin is installed therein. Other possible configurations for electrically connecting the anode body to the power supply can be considered without departing from the scope of the present invention.

[0055] The anode body 100, 200 also comprises a body wall 120, 220 around the longitudinal inner hole 110, 210. The body wall comprises or defines the following portions: a first or open portion 130, 230 adjacent an opening 111, 211 of the longitudinal inner hole; a second or closed portion 140, 240, opposite the open portion 130, 230; and a middle portion 150, 250 extending between the first / open portion 130, 230 to the second / closed portion 140, 240.

[0056] As particularly illustrated on Figures 3 or 9, the anode body 100, 200 has a bore shape with a continuous external surface 121, 221 of the body wall forming a round transition 141, 241 between the second / closed portion 140, 240 and the middle portion 150, 250. Such round fillets (no sharp comers), for the closed portion, but also preferably for the middle and first / open portions, allows reducing stress concentrators and avoiding crack initiation.

[0057] As particularly illustrated on Figure 9, the second portion 240 and the middle portion 250 of the body wall 220 of the anode body 200 have a uniform, or nearly uniform, thickness 222. Uniform, or nearly uniform lateral wall and bottom thickness allow for uniform, or nearly uniform electric current distribution across said (nearly) uniform thickness, leading to (nearly) uniform heat transfer and temperature gradients. This is particularly advantageous for preserving temperature sensitive materials, such as ceramics or cermets, from cracking.

[0058] Alternatively, as particularly illustrated on Figure 3, the body wall 120 of the second / closed portion 140 has a first thickness 122 superior to a second thickness 123 of the body wall 120 of the middle portion 150.

[0059] As particularly illustrated on Figure 4a, the closed portion 140 of the anode body 100 may have an circular-like shape. Alternatively, as particularly visible on Figure 10a, the closed portion 240 of the anode body 200 may have a rectangle-like shape with rounded comers. This specific shapes allows reducing cell resistance and achieving more uniform current distribution across the portions of the anode body.

[0060] By “circular”, it is meant in the instant disclosure any geometry from ovoid to circle.

[0061] By “rectangular”, it is meant in the instant disclosure any geometry from a rectangle to a square.

[0062] As particularly illustrated on Figures 4a-4b, or Figures lOa-lOb, the first / open portion 130, 230 of the body wall 120, 220 and the opening 111, 211 of the longitudinal inner hole 110, 210 may have a circular shape. This circular shape provides more space than a rectangular shape, and as such allow easing the insertion and reception of the electrical pin in the longitudinal hole of the anode body. [0063] As illustrated on Figures 1 and 2, or Figures 7 and 8, the middle portion 150, 250 of the anode body 100, 200 comprises or defines two opposite outer flat surfaces 151, 251 for facing adjacent outer surfaces of cathode bodies (not illustrated) when the anode is plunged into an electrolytic bath of an electrolytic cell comprising said cathode bodies. Preferably, and as aforesaid, cathode bodies may be plates with two opposite flat surfaces for facing adjacent anodes. Other cathode shapes can be considered without departing from the scope of the present invention.

[0064] According to the first embodiment illustrated on Figures 1 to 3, the outer flat surfaces 151 of the anode body are configured to outwardly extend between the second / closed portion and the first / open portion according to an angle a with the longitudinal axis of the inner hole of between 0.5° and 5°. The angle a can be chosen for an accommodation of the bubble plume (or oxygen bubbles) formed during electrolysis using oxygen-evolving electrodes. If during the electrolytic process, the ACD is completely filled or impinged by O2 bubbles - the resistance is higher through gas than liquid. Also, oxygen bubbles should not hit the cathode plates (or the liquid aluminum will back-react to alumina), which may lower the efficiency of the cell.

[0065] According to the second embodiment illustrated on Figures 7-10, the outer flat surfaces 251 of the anode body are configured to be parallel to a plane formed by the adjacent cathode bodies. In other words, the angle a between the outer flat surfaces 251 and the longitudinal axis of the inner hole is about 0°. This characteristic provides a constant anode-cathode distance (ACD) between the middle portion of the anode and adjacent cathodes bodies. In other words, the outer flat surfaces 251 extend according to an angle a of about 0° with the longitudinal axis of the inner hole,

[0066] According to a preferred embodiment, the middle portion 150, 250 of the body wall 110, 210 also comprises two opposite outer lateral surfaces 152, 252 connecting the two opposite outer flat surfaces 151, 251, the outer lateral surfaces forming a round shaped transition 153, 253 between the two opposite outer flat surfaces of the anode body (see e.g. Figures 4a and 10a respectively).

[0067] According to a preferred embodiment, particularly illustrated on Figures 2, 3, and 5, or Figures 8, 9 and 11, the first / open portion 130, 230, typically located at the top of the anode when the anode is vertical, has atop flat surface 131, 231 perpendicular to the longitudinal inner hole or the axis Z. This top flat shape of the electrode body allows for mechanical atachment of the electrode to a refractory package (the refractory package “sits” or distributes its load on this surface). Preferably, the body wall 120, 220 may have a failsafe system adjacent the first / open portion to mechanically connect the electrode to the refractory package. More preferably, the failsafe system comprises an external groove 132, 232 around and adjacent the top open portion, as the one illustrated on Figures 5-6 or 11-12.

[0068] As illustrated on Figures 1 and 5, the outer lateral surfaces 152 of the anode body 100 extend inwardly from the second/closed portion 140 of the body to the first/open portion 130 thereof. As illustrated on Figures 7, 8 and 11, the outer lateral surfaces 252 of the anode body 200 also extend inwardly from the second / closed portion 240 of the body. Regarding the anode body illustrated on Figure 11 for instance, the inwardly extending outer surface 252 defines a round transition forming a shoulder 254 between the middle portion 250 and the open portion 230. These configurations of the outer lateral surfaces 152-252 of the anode body allow increasing the surface area, thereby decreasing the current density, cell voltage, and specific energy consumption.

[0069] The present invention preferably concerns anode bodies made from metals or alloys thereof, ceramics, or cermet materials typically used for that manufacturing of inert or oxy gen-evolving anode.

[0070] Accordingly, the present invention also concerns any electrode comprising at least the electrode body as defined herein, and an electrode pin inserted into the electrode body.

[0071] The present invention also concerns an electrode assembly comprising a plurality of the electrodes as disclosed herein operatively connected to a refractory package and means of current distribution.

[0072] The electrode body or electrode comprising the same as disclosed herein is particularly useful for the making of a metal, preferably aluminum.

[0073] Preferably, an electrode body according to the present invention:

• may have a closed end/bore shape which allows receiving electrical member (pin) for reducing cell resistance and achieving more uniform current distribution across the part.

• may have similar or close wall and botom thicknesses for the anode body wall which allows for uniform heat transfer/temperature gradients for temperature sensitive materials (e.g. ceramics, cermets, etc).

• may comprise only fillets with no sharp comers for reducing stress concentrators, avoiding as such crack initiation.

• may provide an increased aspect ratio of cylinder which allows for larger ACO and lower Specific Energy Consumption or SEC (needed preferably for vertical cell design);

• comprises flat outer surfaces (width) which reduce the average ACD compared to a simpler cylindrical shape, lower SEC. In other words, by flattening the electroactive surface of the anode, the average ACD is reduced while maintaining the same minimum ACD;

• provides extra wall thickness on oval "ends" (between anodes) to increase life due to non-uniform wear patterns of anodes, the wall thickness between anodes being preferably thicker than the wall thickness between anode and cathode.

• may provide larger anode, maximize surface area for electrolysis and reduce the number of parts per anode assembly (e.g. the number of electrical connections);

• may provide combination shape of oval-esque for electrolysis and a round bore for pin;

• may provide a reduced width above the electrolytic bath - save material and allow for structural integrity of refractory package (holes would be too big in slab);

• can simplify the manufacturing processes such as shaping, handling, sintering, etc., due to the electrodes’ flat faces, for instance by maintaining shape and dimensional tolerances during part shrinkage; and/or

• has a larger wall thickness than known electrode bodies connected with a pin, increasing as such the electrode life.

[0074] According to a preferred embodiment, the electrode body according to the present disclosure is an anode body with a hollow shape, allowing the hollow body to be fdled with a metallic material to conduct electricity to as close as possible to the active anode surface. The hollow shape also allows minimizing the resistive losses and also facilitating a uniform current density over the active anode surface.

[0075] Several preferred embodiments of the electrode body as disclosed herein represent additional significant improvements over electrodes with cylindrical or flat bodies, in particular due to the body transitions from a rectangular shaped cavity in the bottom to a circular shaped cavity at the top of the anode. This provides several benefits:

- First, the pin life is limited by the smallest cross-sectional dimension. For a given cross sectional area, a circular geometry will be best since a rectangular geometry will always have a smaller dimension.

Second, as mentioned herein, circular cross section of the anode at the top facilitates a more robust (mechanically) refractory package required at the very top of the anodes.

- Third, an axisymmetric shape allows a more efficient manufacturing method for the pin.

- Fourth, a circular opening of the anode top avoids sagging and deformation of the anode opening that can occur during manufacturing of the anode if the opening is rectangular and the gravity force is normal to the long axis of the opening. A circular opening has the natural mechanical strength of an arch when forces are applied normal to the anode surface.

[0076] While illustrative and presently preferred embodiments of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.

Claims

CLAIMS What is claimed is:

1. An electrode body of an electrode for the electrolytic production of a metal, the electrode body extending longitudinally along an axis Z and comprising: a first portion configured for operatively connecting the electrode body to an electrolytic cell; a second portion, opposite the first portion; and a middle portion extending between the first and second portions; wherein the electrode body has a continuous external surface forming a round transition between the second and middle portions, and wherein the continuous external surface of the middle portion defines two opposite outer flat surfaces for facing surfaces of adjacent electrodes when the electrode is plunged into an electrolytic bath of an electrolytic cell comprising said adjacent electrodes.

2. The electrode body according to claim 1, further comprising a longitudinal inner hole extending from the first portion and configured for receiving, at least in part, an electrode pin for operatively connecting the electrode body to an electric power supply when the electrode pin is installed therein, the longitudinal inner hole and the electrode body then defining a body wall around the longitudinal inner hole.

3. The electrode body according to claim 2, wherein the longitudinal inner hole defines a non-uniform cross-sectional area between the first and second portions of the electrode body.

4. The electrode body according to claim 3, wherein the non-uniform cross-sectional area of the inner hole adjacent the first portion is larger than the non-uniform cross- sectional area adjacent the middle and/or second portions.

5. The electrode body according to claim 2, wherein the non-uniform cross-sectional area of the inner hole adjacent the first portion has a first geometry that is different than a second geometry of the non-uniform cross-sectional area adjacent the second portion.

6. The electrode body according to claim 5, wherein the first geometry defines a circular cross-sectional area whereas the second geometry defines a rectangular cross- sectional area.

7. The electrode body according to any one of claims 2 to 5, wherein the second portion of the electrode body is closed and wherein the body wall defined by the second and middle portions has a uniform or nearly uniform thickness.

8. The electrode body according to any one of claims 2 to 5, wherein the second portion of the electrode body is closed and wherein the body wall defined by the second portion has a first thickness superior to a second thickness of the body wall defined by the middle portion.

9. The electrode body according to any one of claims 1 to 8, wherein the second portion of the electrode body has an oval-like shape or a rectangle-like shape with round comers.

10. The electrode body according to any one of claims 1 to 9, wherein the first portion of the body wall has a circular or oval shape.

11. The electrode body according to any one of claims 1 to 10, wherein the outer flat surfaces are configured to extend from the second portion to the first portion according to an angle a with the longitudinal axis Z of about 0° such as to be parallel to a plane formed by the adjacent electrodes’ surfaces and provide a constant distance between the middle portion of the electrode body and adjacent electrodes.

12. The electrode body according to any one of claim 1 to 10, wherein the outer flat surfaces are configured to inwardly extend from the second portion to the first portion according to an angle a with the longitudinal axis Z of between about 0,5° and about 5°.

13. The electrode body according to any one of claims 1 to 12, wherein the middle portion of the body wall also comprises two opposite outer lateral surfaces connecting the two opposite outer flat surfaces, the outer lateral surfaces forming a round shaped transition between the two opposite outer flat surfaces of the electrode body.

14. The electrode body according to claim 13, wherein each of the outer lateral surfaces extends inwardly from the second portion to the first portion.

15. The electrode body according to claim 13 or 14, wherein each of the two inwardly extending opposite outer lateral surfaces defines a shoulder-shaped transition along the longitudinal axis Z between the middle portion and the first portion.

16. The electrode body according to any one of claims 1 to 15, further comprising a failsafe system adjacent the first portion to mechanically connect the electrode body to the refractory package.

17. The electrode body according to claim 16, wherein the failsafe system comprises an external groove in the electrode body around and adjacent the first portion.

18. The electrode body according to any one of claims 1 to 17, wherein the electrode is an anode, and the electrode body is an anode body made from a metal or alloy thereof, a ceramic or a cermet material to form an inert or oxy gen-evolving anode.

19. An electrode comprising the electrode body as defined in any one of claims 1 to 18 and an electrode pin inserted into the electrode body.

20. The electrode according to claim 19 for use for the making of a metal.

21. The electrode according to claim 20, wherein the metal is aluminum.

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