JP2024521488A - Mold and copper anode for producing high purity copper - Google Patents

Abstract

A mold (7) for producing a copper anode (1) for producing high purity copper, characterized in that it has: a flat first cavity (8) defined by two side surfaces aligned parallel to one another; two second cavities (9) fluidly connected to the first cavity, the two second cavities being located at different corners on the peripheral side of the first cavity (8) and extending laterally outward away from the first cavity (9); and a core (20) is provided in the center of each of the second cavities (9), the core dividing each second cavity (9) into an at least partially circumferentially closed annular shape. [Selected Figure] Figure 8

Description

The present invention relates to a mold for producing high purity copper having the features of the preamble of claim 1, and a copper anode for producing high purity copper having the features of the preamble of claim 6.

Multiple metallic materials are poured in a molten state into a mold to produce a workpiece having a predetermined profile. For example, such casting processes are carried out in the manufacture of copper anodes, which are produced as an intermediate step in copper production to produce high purity copper as the final product.

Typical copper production is carried out by melting and oxidation over several process steps from copper sulfide concentrates (or from copper-containing secondary materials and copper scrap) to produce a product with a proportion of pure copper of more than 90% by weight. This raw copper (or raw copper) is then processed into copper anodes, which are subjected to electrolytic refining in electrolytic cells. A typical processing of raw copper into anodes is carried out such that liquid raw copper is poured into a metal mold. The use of copper molds, which are coated with a release agent before pouring the liquid raw copper into them, has been found to be particularly useful in making the subsequent demolding process easier.

As shown in Figure 1, raw copper is formed and solidified using a rectangular geometric shape of an anode plate (10) with holding arms (2). The most frequently used method of pouring raw copper is by a casting wheel containing a certain amount of copper casting mold, into which raw copper is poured at a temperature of at least 1100°C. After the copper is poured into the casting wheel, the casting wheel starts to rotate, and then the molten raw copper is cooled at ambient temperature until the top of the raw copper solidifies. The raw copper then passes through a cooling stage with upper and lower water cooling. During this stage, the raw copper is reduced in temperature until it reaches a completely solid state.

The raw copper is poured into a mould (7) having a rectangular central first cavity (8) for receiving the liquid raw copper and forming the anode plate (10). At the top of the mould (7), at the corners of the central first cavity (8), there are two second cavities (9) for receiving the liquid copper, said cavities forming the holding arms (2) of the cast anode plate (10), as seen in Figures 6 and 7.

In the smelter, the copper anode (1) is inserted into the electrolytic cell (3) with the cathode (4), which, depending on the process used, is either undissolved or formed in the form of a master plate with a corresponding hanging rod (5). The copper anode (1) is placed on the contacts (6), each in the form of a conductor rail, by means of the holding arms (2). The electrolytic cell (3) is filled with an acid solution and a voltage is applied to the contacts (6) in order to cause electrowinning of copper in the direction from the copper anode (1) to the cathode (4), as shown in Figures 2 to 5. In this way, the copper anode (1) remains immersed only up to its upper edge. Thus, the upper part of the copper anode (1) with the holding arms (2) does not participate in the electrolysis process, as shown in Figure 3. Thus, the holding arms (2) only serve to transport the anode plate (1) or the anode waste after electrolysis and to create an electrical contact between the external conductor rail formed by the contacts (6) and the anode plate (1). Therefore, the holding arm (2) must have a certain rigidity or load-bearing capacity to absorb the forces transmitted during transport and holding of the copper anode (1) in the electrolysis cell (3). In particular, the high weight of the copper anode (1) of 200-400 kg must be taken into account. In addition, the holding arm (2) must have a correspondingly flat conductive surface, which must have a certain minimum surface area for the maximum current density that must be taken into account.

After the electrolysis cycle is finished, a portion of the holding arm (2) and the anode plate (10) remain, together forming the remainder of the copper anode (1). This material must be completely melted again to form a new copper anode (1) and continue the complete cycle. The transportation and repeated melting of the anode waste represents follow-up costs, which are a key factor in the cost-effectiveness of the high purity copper production process. The mass of the anode waste is important, since it limits or reduces the effectiveness of the electrolysis process in terms of the separated high purity copper relative to the raw copper used. In the case of manual transport, the weight of the anode waste is particularly important, since the anode waste must be further handled and transported.

Various solutions for reducing the anode waste are further known in the prior art. Document DE 11 2012 003 846 T5 describes a system consisting of a reusable anode suspension device and an anode without a holding arm. The amount of anode waste can undoubtedly be reduced since the anode waste lacks a holding arm, but this does not lead to a reduction in costs. Instead, the use of such an anode suspension device leads to higher follow-up costs, since firstly the anode without a holding arm has to be mechanically connected to the anode suspension device before it can be used in the electrolysis process, and the anode waste has to be separated from the anode suspension device after the electrolysis process has ended. In addition to the mounting process, further cost factors are the manufacturing costs, as well as the costs for maintaining and caring for the anode suspension device. Further electrode assemblies with a suspension device are known, for example, from EP 3 748 041 A1, but again have the disadvantage that the suspension device has to be connected to the anode first in a mechanical mounting process.

Document DE 11 2015 003 170 T5 describes a suspension rail for carrying an anode without a holding arm, which is completely immersed in the electrolyte. Unlike the anode suspension device described in DE 11 2012 003 846 T5, which uses a rigid, inflexible holding arm, the suspension rail is equipped with a pivotable holding arm. A disadvantage of the described suspension rail is the complex mechanism for securely holding the anode. Moreover, in the usual conditions of an industrial-scale electrolysis process, significant mechanical loads are applied to the suspension rail during transportation and suspension in the electrolysis cell, as a result of which the suspension rail is exposed to significant wear, which increases the complexity of the maintenance. This disadvantage is further increased by immersing the suspension rail in the electrolyte, since, depending on the system, an encrustation always forms in the upper region, thus here in the region of the suspension rail. To ensure the functionality of the suspension rail mechanism, the resulting sheathing must be removed, which further increases the complexity of maintenance, especially due to the necessary mobility of the holding arms.

Document CN 106835196 describes an electrode plate provided with conductive holders on both sides. Conventional metal anodes are hung from these holders on both sides by means of holding arms. The electrode plate with the anodes hung on both sides is then suspended in an electrolytic cell, so that the anodes are completely immersed in the electrolyte. During the electrolysis process, the suspended anode slowly dissolves in the electrolyte, thereby reaching a state in which the mechanical stability of the anode's holding arms no longer guarantees to support the remaining weight of the partially dissolved anode. The partially dissolved anode therefore falls into the electrolytic cell and must then be removed from the cell in order to avoid electrical short circuits. It is not possible for the anode to completely dissolve without dropping the anode waste together with this electrode plate.

A further problem with the design of the copper anode (1) is that the copper anode (1) itself heats up to a temperature of about 60° C. in the electrolysis process. This basic heating of the copper anode (1) can lead to an increased temperature of up to 150° C. in the region of the holding arm (2) in case of a short circuit of the copper anode (1) itself or of an adjacent copper anode (1), which reduces the stiffness of the copper anode (1) in the region of the holding arm (2). However, this heating of the holding arm (2) and the associated reduction in stiffness should not in any case lead to the holding arm (2) no longer being able to perform its holding function (2) or to the copper anode (1) tilting in the electrolysis cell due to deformation of the holding arm (2).

A further problem with such copper anodes is that, due to their large volume, the recesses in the mould provided for forming the retaining arms are filled unevenly with the liquid copper due to the oscillatory movement of the liquid copper as it flows in, which results in retaining arms with uneven contours, in particular with different or varying thicknesses, after the copper has solidified.

Against this background, it is an object of the present invention to provide a mold that allows copper anodes having holding arms to be cast with improved dimensional accuracy. It is a further object of the present invention to provide a copper anode that can be cast with improved dimensional accuracy.

According to the present invention, to solve this object, a mold for producing copper anodes for producing high purity copper is proposed, said mold having a flat first cavity delimited by two side faces aligned parallel to each other and two second cavities fluidly connected to the first cavity, the second cavities being arranged at different corners on the peripheral side of the first cavity and extending laterally outward away from the first cavity, the principle of the present invention being that a core is provided centrally in each of the second cavities, said cores dividing each second cavity into at least partially closed annular shapes in the circumferential direction. The cores form a barrier or impact wall for the raw copper flowing into the second cavities, said cores slowing down the flow rate of the raw copper and forcing the raw copper laterally into the annular cavities. Thus, the flow of raw copper can be homogenized, which allows the second cavities to be filled more uniformly, in particular more completely, with raw copper. The second cavity is in the form of a channel, which is completed through the first cavity and forms a closed ring. It should be understood that this means that the second cavity does not have to be completely divided into an annular shape by the core. It is sufficient if the core has a height smaller than the depth of the second cavity or divides only the inlet opening of the second cavity and thus acts as a barrier that slows down the flow of raw copper, so that the retaining arm is cast with a more uniform and in particular more constant thickness.

However, the core can also be dimensioned such that it divides the second cavity completely circumferentially into a closed annular shape. In this case, the flow of raw copper is maximally slowed down and homogenized. Through the core, it is further possible to cast a copper anode which has a through opening in the area of the holding arms and is therefore as reduced as possible in terms of its weight in the area of the holding arms.

Alternatively, it is proposed that the core divides the second cavity into a first portion having a closed annular shape and a second flat portion, the second flat portion being disposed transversely on the first portion. The core therefore forms, by its shape, a second flat portion within the second cavity, which further slows down and homogenizes the flow of raw copper into the second cavity.

Furthermore, it is proposed that the core is divided into two partial cores by a gap, which in fact creates an additional flow connection between the two edges of the annular first part of the second cavity and thus allows for an improved, in particular more uniform and more complete filling of the second cavity with raw copper.

The gap is preferably aligned at an angle of 0-45 degrees relative to the central longitudinal axis of the first cavity, which corresponds to the main flow direction of the feed copper entering the mold. With the proposed gap alignment, the feed copper flows vectorially into the gap in the primary direction of the main flow direction of the feed copper.

To solve this object, a copper anode for producing high purity copper is proposed, which comprises an anode sheet and at least two holding arms, at least one of which is provided with at least one recess, which is formed integrally with the anode sheet. The advantage of the invention is that due to the recesses in the proposed holding arms, cores have to be provided in the mould cavities to produce the holding arms. During the casting process, these cores form a barrier for the incoming raw material and reduce the volume of the cavity in the mould that is filled with raw copper, which in turn leads the raw copper to flow more slowly and more uniformly into the side conduits near the cores. This homogenisation of the flow of liquid raw copper results in the holding arms being cast with a more uniform thickness than in the case of moulds with coreless cavities for the holding arms of copper anodes known in the prior art.

A further advantage of the solution according to the invention is that the proportion of anode waste relative to the raw copper of the entire copper anode, and thus the proportion of raw copper of the copper anode that cannot be dissolved, can be reduced by the recess. This can increase the effectiveness of the separation and thus the amount of separated high-purity copper relative to the total amount of raw copper used in the copper anode. Furthermore, the weight of the copper anode before electrolysis and, particularly advantageously, the weight of the anode waste remaining after electrolysis can be reduced. This has advantages during handling and saves on transportation costs. In addition, the cost of repeated melting is reduced, since the mass of the anode waste to be melted is lower. The copper anode according to the invention is purposely formed as one part with the holding arm and the anode plate, so that the attachment of the holding arm or anode suspension device to the anode plate and the maintenance of the reusable holding arm or anode suspension device, which is required in the solutions known from the prior art, can be omitted. The recess should therefore be understood to mean a depression (or recess/depression) of the holding arm, which extends into the holding arm relative to a plane extending through the anode plate. In this way, the overall dimensions remain the same but the weight is reduced.

Furthermore, the copper anode according to the invention can be manufactured by a single casting process with the anode plate and the holding arm and then suspended in the electrolysis bath without further processing, in particular without further mounting steps. In addition to forming an electrical contact, the holding arm performs the central function in handling and holding the copper anode weighing 200-400 kg during transportation and in the electrolysis bath. For this purpose, the holding arm must have a sufficiently high rigidity and load-bearing capacity, which is obtained by a correspondingly thick dimensioning of the holding arm. For this reason, in the prior art, the holding arm, which is integrally (or as one part) molded on the anode plate, is made to be intentionally rigid and correspondingly solid.

The inventive achievement of the proposed solution is that, in particular, even with increasing heat input, despite the central requirement for load-bearing capacity, at least one recess is provided in the holding arm, through which the above-mentioned advantages can be obtained. The recess is dimensioned such that, even with increasing heat input, the load-bearing capacity of the holding arm is sufficient to hold the copper anode as intended during transport and in the electrolysis cell. This is achieved by obtaining a weight reduction through the recess, in particular so that the external dimensions, which are particularly important for stiffness, do not change.

Furthermore, it is proposed that the recesses have a shape that corresponds to the scaled-down outer shape of the holding arm. Due to the reduced shape of the recesses, the respective holding arm is reduced as much as possible in its weight and in the mass of raw copper, but at the same time is thinned (or weakened) as homogeneously as possible, so that the maximum stresses in the holding arms during holding and handling of the copper anodes can be reduced to values as low as possible and as homogeneous as possible.

It is further proposed that the recess is at least partially closed by a support wall. The support wall forms additional stiffness of the holding arm in the region of the recess, which may achieve an improved compromise between the two requirements, in particular the required stiffness and the reduction of weight. The thickness of the support wall is therefore an additional available design parameter to obtain the required load-bearing capacity of the holding arm.

It is further proposed that the depth of the recess to the support wall corresponds to at least half the thickness of the retaining arm perpendicular to the plane extending through the anode sheet. The support wall therefore has a thickness which corresponds at most to half the thickness of the retaining arm. In this way, a substantial weight reduction can be obtained with simultaneous sufficient rigidity of the retaining arm.

The weight reduction can be further increased by forming the recess at least partially as a through-opening. Moreover, the through-opening thus created can further be used for transporting the copper anode by means of a corresponding hanging hook or hanging device.

It is further proposed that the recess is divided into two partial recesses by a reinforcing rib. The reinforcing rib essentially forms a bar dividing the recess, said bar reinforcing the retaining arm in the manner of a framework, whereby the stiffness of the retaining arm can be significantly influenced by the thickness and the orientation (or alignment) of the reinforcing rib.

It is further proposed that the reinforcing ribs are aligned at an angle of 0° to 45° with respect to the longitudinal central axis of the anode sheet extending between the retaining arms. With the proposed orientation, the retaining arms are particularly reinforced against tensile stresses caused by gravity acting on the copper anode in a suspended arrangement of the copper anode.

Furthermore, it is proposed that the recess is dimensioned in such a way that, in the plane in which the holding arm extends through the anode sheet, it has at least partially a greater wall strength on the side of the electrical contact surface than on the side without the electrical contact surface. The advantage of this solution is that the holding arm has a thicker wall thickness in the area of the introduction of the current flow, so that the current density in the holding arm can be specifically reduced in this area, while the side on which the contact surface is not provided is purposely made thinner for the purpose of reducing weight. If the copper anode is provided with a side of the holding arm with an electrical contact surface for contacting the external conductor rail, the holding arm is additionally reinforced in a targeted manner on the underside, where tensile stresses act that are decisive for the deformation of the holding arm when the copper anode is held on the conductor rail. The corresponding thicker dimension of the holding arm on this side makes it possible to reduce the maximum tensile stress acting in the holding arm and, as a result, to increase the load-bearing capacity of the holding arm.

The invention will now be described in more detail below with reference to preferred embodiments and with reference to the accompanying drawings, in which:
1-7 show related moulds and electrolysis cells according to the prior art. 8-16 show different anodes according to the present invention along with associated molds of different exemplary embodiments.

In FIG. 8 one can see a mould 7 (open on one side for better visibility) for producing a copper anode 1, which can be seen in FIG. 9, according to a first embodiment of the invention. The mould 7 has a first cavity 8 for producing an anode sheet 10 and two second cavities 9 adjacent to the anode sheet for producing a retaining arm 2. The first cavity 8 is flat with a rectangular shape and has sides aligned parallel to each other with a distance corresponding to the thickness of the anode sheet 10. The second cavity is divided by a central core 20 into a first annular part 24 in the form of a channel and a flat second part 25, in which the height of the core is lower than the depth of the second cavity 9. The first annular part 24 in the form of a channel is completed through the first cavity 8 to form a closed ring and is further fluidically connected to the first cavity 8. The flat second part 25 of the second cavity 9 arises from the lower height of the core 20, extends over the entire side of the core 20 and transitions at its edge into the first annular part 24 and is thus fluidically connected to the first annular part. The copper anode 1 is cast by pouring liquid raw copper into a mold 7, as described earlier in this specification and also shown in connection with the exemplary embodiment of FIG. 16.

The copper anode 1 cast in the mold 7, which can be seen in FIG. 9, has a flat rectangular anode sheet 10 with a substantially constant thickness in the plane of the drawing. Two retaining arms 2 are molded in one piece on the upper edge of the anode sheet 10, said retaining arms also having a substantially constant thickness in the plane of the drawing. The retaining arms 2 project upwards and outwards from the anode plate 10 and each form a contact surface 12 on its underside for contacting a contact 6 in the form of a conductor rail (see FIGS. 3 to 5).

Due to the shape of the second cavity 9 with the central core 20, the retaining arms 2 each have an upper edge 14 formed to correspond to the shape of the first portion 24 in the form of a channel, and a lower edge 13, which are connected to each other at their ends and enclose between them a recess 11, which is formed by the shape of the core 20. The recesses 11 are closed at their rear side in the figure by a support wall 15 formed by the shape of the flat second portion 25 of the second cavity 9. The support wall 15 is formed by a flat wall aligned parallel to a plane extending through the anode sheet 10. The plane extending through the anode sheet 10 corresponds to the drawing plane and is described below only as plane I, which also applies to the subsequent exemplary embodiments.

16, the core 20 provided in the second cavity 9 acts as a barrier against the raw copper flowing in when casting the copper anode 1 to form the recess 11. The raw copper flowing in is thus forced through the side of the barrier into the second cavity 9, where it is formed annularly in the first part 24, corresponding to the edges 13 and 14 to be formed, and flat in the second part 25 to form the support wall 15. The flow of raw copper is thus slowed down and at the same time homogenized, which also leads to a more uniform thickness of the holding arm 2 of the copper anode 1 after casting. Starting from the first cavity 8, the raw copper flows into the second cavity 9 through the first part 24 in the form of a channel and at the same time through the second flat part 25 of the end face.

In the mould 7 known from the prior art, which can be seen in FIG. 7, there is no core 20, which would allow the raw copper to flow unhindered into the corresponding cavity 9, which has a larger volume, and to rock upwards and solidify to form a retaining arm 2 of different thickness. This result is avoided by the provided core 20, which allows the second cavity 9 to be filled more evenly and more completely with the liquid raw copper, which leads to the retaining arm 2 of the cast copper anode 1 having a substantially more constant thickness and a more uniform surface.

The recess 11 is formed by a depression in the holding arm 2, which further reduces the amount of raw copper injected into the holding arm 2. The outer dimensions of the holding arm 2 are not intentionally reduced, since a particularly high load-bearing capacity and stiffness of the holding arm 2 can be obtained through correspondingly large outer dimensions. The lower edge 13 and the upper edge 14 of the holding arm 2 have a substantially constant wall thickness B in the plane I, so that the recess 11 has a reduced shape relative to the outer shape of the holding arm 2. However, the lower edge 13 can also have a slightly larger wall strength, so that a corresponding flat contact surface 12 can be created through milling or sanding of the surface, without reducing the load-bearing capacity of the holding arm 2 to such an extent that it can no longer perform its holding function.

The holding arms 2 are lightened by the recesses 11 and at the same time reinforced by the support walls 15. The support walls 15 are aligned parallel to the plane I of the anode sheet 10, so that the holding arms 2 are reinforced as much as possible against tensile stresses acting in the plane I. They therefore have the necessary load-bearing capacity to handle and support the copper anodes 1 and at the same time their mass is reduced, so that the waste portion of the copper anodes 1 after the electrolysis process is reduced, with the above-mentioned advantages. Being arranged parallel to the plane I, the support walls 15 are aligned parallel to the gravitational force acting on the copper anodes 1 when lifting them and when suspending them in the electrolysis bath, thus causing maximum reinforcement of the holding arms 2 against the pressing forces applied via the contact surface 12 when supporting the copper anodes 1.

10 and 11, a second, further developed exemplary embodiment of the invention can be seen, in which the retaining arm 2 on the right side of the figure has a recess 11, which is closed on one side at the top by a support wall 15. The support wall 15 intentionally does not completely cover the recess 11, which is formed as a through opening 16 at the bottom. The retaining arm 2 on the left side of the figure is formed according to the retaining arm 2 of FIG. 9. The right retaining arm 2 is thus further lightened by the through opening 16, and the dimensions and shape of the support wall 15 can be shape-optimized with respect to the stiffness of the resulting retaining arm, for example by means of finite element calculations. The recess 11 is then formed by a core 20 in the second cavity 9 of the mold 7, and the through opening 16 is formed by the core 20 having a height corresponding to the depth of the second cavity 9, thus completely dividing the second cavity 9 into a first annular portion 24 in the form of a channel without a second portion 25.

12 and 13, a further exemplary embodiment can be seen in which the recesses 11 of both holding arms 2 are formed completely as through openings 16, which can further maximize the weight reduction. In this case, the required stiffness of the holding arms 2 is obtained only by the dimensions at the edges 13 and 14 of the holding arms 2, where in particular the dimensions of the wall strength (or wall thickness/Wandstaerke) B of the edges 13 and 14 in plane I are available.

14 and 15, a further exemplary embodiment of the invention can be seen in which the recesses 11 of the holding arms 2 are each formed by a through opening 16, said through openings being divided into two partial through openings 18 and 19, respectively, by a reinforcing rib 17 in the form of a framework. In this exemplary embodiment, the reinforcing ribs 17 are aligned or arranged such that their longitudinal axis C extends approximately parallel to the central longitudinal axis A of the anode sheet 10. By means of the reinforcing ribs 17, the holding arms 2 are reinforced using as little material or additional weight as possible, in which case an alignment parallel to the central longitudinal axis A is particularly advantageous, since the reinforcing ribs 17 reinforce the holding arms 2 particularly effectively against the pressing forces acting on the contact surface 12. However, the reinforcing ribs 17 can also be aligned at an angle of up to 45 degrees to the central longitudinal axis A, still causing an effective reinforcement of the holding arms 2.

For this purpose, the core 20 in the second cavity 9 is divided by a gap 21 into two partial cores 22 and 23. A reinforcing rib 17 is cast through the gap 21, said reinforcing rib separating the partial through openings 18 and 19 formed by the partial cores 22 and 23 from each other.

A decisive advantage of the solution according to the invention is that the weight of the anode waste can be reduced and the effectiveness of the electrolysis method for the raw copper used can be very easily increased, without sacrificing the advantages of a significantly more cost-effective integral production of the copper anode 1 with the anode plate 10 having the holding arm 2. The recess 11 is purposefully designed as a depression in the holding arm 2 and thus as a cavity extending from the flat surface of the holding arm 2 into the holding arm 2, so that a high stiffness of the holding arm 2 caused by the held contour is created and at the same time the weight of the holding arm 2 can be reduced via the recess 11 provided therein. The recess 11 is purposefully provided in the holding arm 2, so that the amount of high-purity copper produced is not reduced, since the holding arm 2 is not destroyed in the electrolysis process and therefore does not contribute to the collection of high-purity copper.

Claims (15)

A mold (7) for producing a copper anode (1) for producing high purity copper, comprising:
- a flat first cavity (8) defined by two side surfaces aligned parallel to one another;
- two second cavities (9) fluidly connected to the first cavity, the two second cavities (9) being arranged at different peripheral corners of the first cavity (8) and extending laterally outwardly away from the first cavity (9);
- a mould (7), characterized in that each of said second cavities (9) is provided centrally with a core (20), said core dividing each of said second cavities (9), at least partially, in the circumferential direction into a closed annular shape. - A mold (7) according to claim 1, characterized in that the core (20) divides the second cavity (9) completely into a circumferentially closed annular shape. - A mold (7) according to claim 1, characterized in that the core (20) divides the second cavity (9) into a first part (24) having a closed annular shape and a second flat part (25), the second flat part being arranged transversely on the first part. - A mold (7) according to any one of claims 1 to 3, characterized in that the core (20) is divided into two partial cores (22, 23) by a gap (21). - A mold (7) according to claim 4, characterized in that the gap (21) is aligned at an angle of 0 to 45 degrees with respect to the central longitudinal axis (4) of the first cavity (8). - an anode sheet (10),
- at least two retaining arms (2),
A copper anode (1) for producing high purity copper, wherein at least one of said holding arms (2) is provided with at least one recess (11),
A copper anode (1), characterized in that said retaining arms (2) are formed integrally with said anode sheet (10). - A copper anode (1) according to claim 6, characterized in that the recess (11) has a shape corresponding to the reduced outer shape of the holding arm (2). - A copper anode (1) according to claim 6 or 7, characterized in that the recess (11) is at least partially closed by a support wall (15). - A copper anode (1) according to claim 8, characterized in that the depth of the recess (11) to the support wall (15) corresponds to at least half the thickness of the retaining arm (2) perpendicular to a plane I extending through the anode sheet (10). - A copper anode (1) according to any one of claims 6 to 9, characterized in that the recess (11) is at least partially formed as a through opening (16). - A copper anode (1) according to any one of claims 6 to 10, characterized in that the recess (11) is divided into two partial recesses (18, 19) by a reinforcing rib (17). - A copper anode (1) according to claim 11, characterized in that the reinforcing rib (17) is aligned at an angle of 0° to 45° with respect to a central longitudinal axis (A) of the anode sheet (10) extending between the retaining arms (2). - A copper anode (1) according to any one of claims 6 to 12, characterized in that the recess (11) is dimensioned such that the retaining arm (2) has, in a plane I extending through the anode sheet (10), at least partially greater wall strength on the side of the electrical contact surface (12) than on the side not having the electrical contact surface (12). - A copper anode (1) according to any one of claims 6 to 13, characterized in that the retaining arm (2) has a constant thickness with respect to a plane I extending through the anode sheet (10). A copper anode (1) according to any one of claims 6 to 14, characterized in that said copper anode (1) is cast in a mould (7) according to any one of claims 1 to 5.

Images