CA3222395A1 - Casting mould and copper anode for producing high-purity copper - Google Patents

Abstract

The invention relates to a casting mould (7) for producing copper anodes (1) for producing high-purity copper, having - a first, extensive cavity (8), which is delimited by two side faces oriented parallel to one another, and - two second cavities (9) which are fluidically connected to the first cavity, are arranged on a peripheral side of the first cavity (8) at different corners and extend laterally outwardly away from the first cavity (9), characterized in that - a core (20) is provided centrally in each of the second cavities (9), said core (20) subdividing each second cavity (9) at least partially to form a circumferentially closed ring shape.

Description

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CASTING MOULD AND COPPER ANODE FOR PRODUCING HIGH-PURITY COPPER
The present invention relates to a casting mould for producing high-purity copper having the features of the preamble of claim 1 and to a copper anode for producing high-purity copper having the features of the preamble of claim 6.
In a melted state, a plurality of metal materials is poured into moulds to produce workpieces with a pre-determined contour. For example, such a casting process is carried out when producing copper anodes. Such copper anodes are produced in an intermediate step in copper production in order to produce high-purity copper as the end product.
Typical copper production is carried out such that a product with a proportion by weight of more than 90% pure copper is produced from sulfidic copper concentrates (or from copper-containing secondary materials and copper scrap) by melting and oxidisation over several process steps. This raw copper is then processed into copper anodes, which are subjected to an electrolytic refinement in electrolysis baths. A typical processing of the raw copper into anodes is carried out such that the liquid raw copper is poured into metallic moulds. The use of moulds made of copper, which are coated with a release agent before pouring in the liquid raw copper, has in particular proved useful for making a subsequent de-moulding process easier.
The raw copper is formed and solidified with a rectangular geometry of an anode plate (10) with holding arms (2), as shown in Fig. 1. Copper is most frequently cast by means of a casting wheel, which casting wheel comprises a particular quantity of copper casting moulds, into which the raw copper is poured at a temperature of at least 1100 C. After the copper is poured into the casting wheel, the casting wheel begins to rotate, and the melted raw copper then cools at an ambient temperature until the upper part of the raw copper is solid. The raw copper then goes through a cooling stage, which has an upper water cooling and a lower water cooling.
During this phase, the raw copper reduces in temperature until it has reached a completely solid state.
The raw copper is poured into a mould (7), which has a rectangular central first cavity (8) for receiving the liquid raw copper to form the anode plate (10). On the upper part of the mould (7) on the corners of the central first cavity (8), there are two second cavities (9) for receiving the : .

2 liquid copper, said cavities then forming the holding arms (2) of the anode plate (10) to be cast, as can be seen in Fig. 6 and Fig. 7.
In the refineries, the copper anode (1) is inserted into an electrolysis cell

(3), which has a cathode

(4) that, depending on the process used, is formed such that it is undissolved or in the form of a master plate having corresponding hanging rods (5). The copper anode (1) is applied with the holding arms (2) to contacts (6) respectively in the form of a conductor rail.
The electrolysis cell (3) is filled with an acid solution, and an electric voltage is applied to the contacts (6), in order to generate the electrowinning of copper from the copper anode (1) in the direction of the cathode (4), as shown in Fig. 2 to Fig. 5. In this method, the copper anode (1) remains submerged only up to an upper edge. Thus, the upper part of the copper anode (1) with the holding arms (2) is not involved in the electrolysis method, as shown in Fig. 3. The holding arms (2) thus only serve to transport the anode plates (1) or the anode waste after electrolysis and to produce the electrical contact of the anode plate (1) with an external conductor rail, formed by the contacts (6). The holding arms (2) must thus have a particular rigidity or load-bearing capacity to absorb the forces to be transferred during the transport and the holding of the copper anode (1) in the electrolysis cell (3). The high weight of the copper anode (1), of 200 to 400 kg, should in particular be taken into account. In addition, the holding arms (2) must have a correspondingly flat conductive surface, which must have a certain minimum surface area due to the maximum current density which must be taken into account.
After the electrolysis cycle has ended, the holding arms (2) and a part of the anode plate (10) remain, and together form the rest of the copper anode (1). This material must be completely melted again to form a new copper anode (1) and to continue the complete cycle. The transport and the repeated melting of the anode waste means follow-up costs, which is an important factor in the cost-effectiveness of the production method of the high-purity copper.
The mass of the anode waste is important because the effectiveness of the electrolysis method with regards to the separated high-purity copper in relation to the raw copper used is thus limited or reduced. The anode waste must further be handled and transported, such that the weight of the anode waste is in particular of particular importance in the case of manual transport.

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In the prior art, different solutions for reducing anode waste are further known. The document DE
11 2012 003 846 T5 describes a system consisting of a re-usable anode hanging device and an anode without holding arms. The quantity of anode waste can unquestionably be reduced, as the anode waste lacks the holding arms, but this will not lead to a reduction in costs. Instead, the use of such an anode hanging device leads to higher follow-up costs, because firstly, an anode without holding arms must be mechanically connected to the anode hanging device before it is used in an electrolysis method, and the anode waste must be separated from the anode hanging device after the electrolysis method finishes. A further cost factor in addition to the mounting process is the production costs and the costs for maintenance and care of the anode hanging device. A further electrode assembly having a hanging device is, for example, known from EP 3 748 041 Al, which has the disadvantage, however, that here too, the hanging device must first be connected to the anode in a mechanical mounting process.
Document DE 11 2015 003 170 T5 describes a hanging rail for carrying an anode without holding arms, which is completely submerged in the electrolyte. Unlike the anode hanging device described in the document DE 11 2012 003 846 T5, which uses rigid holding arms, the hanging rail is equipped with pivotable holding arms. A disadvantage of the hanging rail described is the complex mechanism for keeping the anode secure. Furthermore, in normal conditions of an industrial-scale electrolysis method, significant mechanical loads are applied to the hanging rail during transport and hanging in the electrolysis bath, such that said hanging rail is exposed to significant wear, which leads to increased maintenance complexity. This disadvantage is additionally increased by submerging the hanging rail in the electrolytes, because, depending on the system, encrustations always form in the upper region, and thus here in the region of the hanging rail. In order to guarantee the functionality of the mechanism of the hanging rail, encrustations which arise must be removed, whereby the complexity of maintenance, in particular due to the requisite moveability of the holding arms, is additionally increased.
Document CN 106835196 describes an electrode plate having electrically conducting holders applied on both sides. Conventional metal anodes are hung on these holders on both sides with holding arms. The electrode plate with the anodes hung on both sides is then hung in an electrolysis bath, whereby the anodes are completely submerged in the electrolyte. During the electrolysis , process, the hung anodes dissolve slowly in the electrolyte, whereby a state is reached from which the mechanical stability of the holding arms of an anode is no longer guaranteed to support the remaining weight of the partially dissolved anode. The partially dissolved anode thus falls into the electrolysis bath, and must then be removed from the latter to avoid an electrical short-circuit. It is not possible for the anodes to completely dissolve without falling anode waste 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 approx. 60 degrees in the electrolysis method. This basic heating of the copper anode (1) can increase to an increased temperature of up to 150 degrees in the region of the holding arms (2) in the event of a short-circuit of the copper anode (1) itself or of a neighbouring copper anode (1), whereby the rigidity of the copper anode (1) in the region of the holding arms (2) is reduced in turn. This heating of the holding arms (2) and the associated reduction in rigidity must never lead, however, to the holding arms (2) no longer being able to fulfil their holding function (2) or the copper anode (1) tipping into the electrolysis bath due to the holding arms (2) deforming.
A further problem with such copper anodes is that, due to their large volume, the recesses in the casting moulds provided for forming the holding arms are unequally filled with liquid raw copper when the liquid raw copper is flowing in, as the raw copper carries out oscillating movements when it is flowing in, which, after the raw copper solidifies, leads in turn to holding arms with an uneven outer shape and in particular with different or varying thicknesses.
Against this background, the object of the invention is to provide a casting mould, which enables copper anodes having holding arms to be cast with an improved dimensional accuracy. The object of the invention is further to provide a copper anode that can be cast with improved dimensional accuracy.
According to the invention, to solve the object, a casting mould for producing copper anodes for producing high-purity copper is proposed, said casting mould having a first flat cavity, which is delimited by two lateral surfaces aligned in parallel with each other, and two second cavities, which are fluidically connected to the first cavity are arranged on different corners on a peripheral side of the first cavity and extend laterally outwardly away from the first cavity, wherein the principle . .
. . . .
of the invention is that a core is respectively centrally provided in the second cavities, said core sub-dividing the respective second cavity at least partially into a closed annular shape in the peripheral direction. The core forms a barrier or impact wall for the raw copper flowing into the second cavity, said core decelerating the inflow speed of the raw copper and pushing the latter laterally into the annular cavity. The flow of the raw copper can thus be homogenised, which in turn enables a more homogeneous and in particular more complete filling of the second cavity with raw copper. The second cavity is in the form of a channel, and completed via the first cavity to form a closed ring. Partially should be understood as meaning that the second cavity need not be completely sub-divided into an annular shape by the core. It is sufficient if the core has a smaller height than the depth of the second cavity, or sub-divides only the inflow opening of the second cavity, and thus acts as a barrier which decelerates the flow of the raw copper, and thus the holding arms are cast with a more homogeneous and in particular more constant thickness.
However, the core can also be dimensioned such that it completely sub-divides the second cavity into a closed annular shape in the peripheral direction. In this case, the flow of the raw copper is decelerated to a maximum and homogenised. Via the core, it is further made possible to cast a copper anode, which has a through opening in the region of the holding arms and which is thus reduced as much as possible in terms of its weight in the region of the holding arms.
As an alternative, it is proposed that the core sub-divides the second cavity into a first portion having a closed annular shape and a second flat portion, wherein the second flat portion is arranged laterally on the first portion. Due to its shape, the core thus forms a second flat portion in the second cavity, which additionally leads the flow of the raw copper into the second cavity to be decelerated and homogenised.
It is further proposed that the core is sub-divided into two partial cores by a gap. The gap practically forms an additional flow connection between the two edges of the annular first portion of the second cavity, and thus enables a further-improved, and in particular more homogeneous and more complete filling of the second cavity with raw copper.
The gap is preferably aligned at an angle of 0 to 45 degrees to a longitudinal central axis of the first cavity. The longitudinal central axis of the first cavity corresponds to the main flow direction of the raw copper flowing into the casting mould. Due to the proposed alignment of the gap, the raw copper flows vectorially into the gap in the main direction in the direction of the main flow direction of the raw copper.
In order to solve the object, a copper anode for producing high-purity copper, said copper anode having an anode sheet and at least two holding arms is proposed, in which at least one recess is provided in at least one of the holding arms, wherein the holding arms are formed as one part with the anode sheet. The advantage of the invention is that, due to the proposed recess in the holding arm, cores must be provided in the cavities of the casting mould to produce the holding arms.
During the casting process, these cores form a barrier for the raw copper which is flowing in and reduce the volume of the cavities in the casting mould to be filled with raw copper, which leads in turn to the raw copper flowing into the side conduits next to the core more slowly and more homogeneously. This homogenisation of the flow of the liquid raw copper leads the holding arms to be cast with a more homogeneous thickness than would be the case for casting moulds having the coreless cavities for the holding arms of the copper anodes known in the prior art.
A further advantage of the solution according to the invention is that the proportion of anode waste, and thus the proportion of the raw copper of the copper anode which cannot be dissolved can be reduced in relation to the raw copper of the entire copper anode by the recess. By implication, the efficacy of the separation, and thus the quantity of the separated high-purity copper in relation to the total amount of the raw copper used in the copper anode can thus be increased. Furthermore, the weight of the copper anode before electrolysis and, particularly advantageously, the weight of the anode waste remaining after electrolysis can thus be reduced. This has advantages during handling and saves transport costs. In addition, the costs for repeated melting are reduced, because the mass of the anode waste to be melted is lower. The copper anode according to the invention is deliberately formed as one part with the holding arms and the anode plate, such that the mounting of the holding arms or anode hanging device on the anode plate and the maintenance of the re-usable holding arms or anode hanging device, which are required in the solutions known from the prior art, can be omitted. The recess should thus be understood to mean a depression in the holding arms, which extends into the holding arms in relation to a plane extending through the anode plate.
The weight reduction is thus obtained while external dimensions remain the same.

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, The copper anode according to the invention is further produced by a single casting process with the anode plate and the holding arms, and can then be hung in the electrolysis bath without further processing, and in particular without further mounting steps. In addition to creating the electrical contact, the holding arms serve a central function in handling and holding the copper anode, which weighs 200 to 400 kg, during transport and in the electrolysis bath. For this purpose, the holding arms must have a sufficiently high rigidity and load-bearing capacity, which is obtained by a correspondingly thick dimensioning of the holding arms. For this reason, the holding arms moulded as one part onto the anode plate are deliberately formed to be rigid and correspondingly solid in the prior art.
The inventive achievement of the suggested solution is that, despite the central requirement for load-bearing capacity, in particular even with an increased heat input, at least one recess is provided in the holding arms, via which recess the advantages specified above can be obtained.
The recess is dimensioned such that the load-bearing capacity of the holding arms, even with an increased heat input, is still sufficient to hold the copper anode as intended during transport and in the electrolysis bath. This is in particular achieved by obtaining the weight reduction via a recess, such that the exterior dimensions, which are particularly important for rigidity, are unchanged.
It is further proposed that the recess has a shape which corresponds to a scaled-down outer shape of the holding arm. Due to the scaled-down shape of the recess, the respective holding arm is reduced as far as possible in its weight and the mass of the raw copper, but simultaneously weakened as homogeneously as possible, such that the maximum stress in the holding arm during holding and handling of the copper anode can be reduced to as low and as homogeneous a value as possible.
It is further proposed that the recess is at least partially closed by a supporting wall. The supporting wall forms an additional rigidity of the holding arm in the region of the recess, whereby an improved compromise between the two requirements, specifically the required rigidity and the reduction in weight, can be realised. The thickness of the supporting wall is thus an additional available design parameter for obtaining the necessary load-bearing capacity of the holding arm.
It is further proposed that the depth of the recess down to the supporting wall corresponds to at least half of the thickness of the holding arm perpendicular to a plane extending through the anode , sheet. The supporting wall thus has a thickness which corresponds at maximum to half of the thickness of the holding arm. A substantial weight reduction with a simultaneously sufficient rigidity of the holding arm can thus be obtained.
The weight reduction can be further increased by forming the recess at least partially as a through opening. Furthermore, the through openings which are thus made can additionally be used to transport the copper anode by hanging corresponding hooks or hanging devices.
It is further proposed that the recess is sub-divided into two partial recesses by means of a stiffening rib. The stiffening rib practically forms a bar which subdivides the recess, said bar stiffening the holding arm in the manner of a framework, whereby the rigidity of the holding arm can be significantly influenced by the thickness and alignment of the stiffening rib.
It is further proposed that the stiffening rib is aligned at an angle of 0 degrees to 45 degrees to a longitudinal central axis of the anode sheet running between the holding arms.
Due to the proposed alignment, the holding arms are specifically stiffened against the tensile stresses caused by gravity acting on the copper anode in the hanging arrangement of the copper anode.
It is further proposed that the recess is dimensioned such that the holding arms at least partially have a greater wall strength on their side of the electrical contact surface in a plane extending through the anode sheet than on the side which does not have an electrical contact surface. The advantage of this solution is that the holding arm has a thicker wall thickness in the region of the introduction of the electrical current flow, such that the current flow density in the holding arm can thus be specifically reduced in this region, while the side on which no contact surface is provided is deliberately formed to be thinner for the purpose of saving more weight. If the copper anode is provided with the side of the holding arm having the electrical contact surface for contacting an external conductor rail, the holding arm is thus additionally stiffened on its underside in a targeted manner, in which underside the tensile stresses act, the latter being decisive for the deformation of the holding arm when the copper anode is held on the conductor rail. Due to the corresponding thicker dimensions of the holding arm on this side, the acting maximum tensile stresses in the holding arm can be reduced, such that the load-bearing capacity of the latter can be increased.

. . . , The invention is explained in more detail in the following with reference to preferred embodiments with reference to the attached figures. Here Fig. 1 to 7 show an associated casting mould and an electrolysis bath according to the prior art; and Fig. 8 to 16 show different anodes according to the invention with associated casting moulds of different exemplary embodiments.
In Figure 8, a casting 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 can be seen. The casting mould 7 has a first cavity 8 for producing an anode sheet 10 and two second cavities 9 adjoining the latter for producing the holding arms 2. The first cavity 8 is flat in the shape of a rectangle, having lateral surfaces aligned in parallel with each other at a spacing corresponding to the thickness of the anode sheet 10. The second cavities are subdivided by a central core 20 into a first annular portion 24 in the form of a channel and a flat second portion 25, in which the core is shorter in height than the depth of the second cavity 9. The first annular portion 24 in the form of a channel is completed via the first cavity 8 to form a closed ring, and is additionally fluidically connected to the first cavity 8. The flat second portion 25 of the second cavity 9 results from the lower height of the core 20 and extends over the entire lateral surface of the core 20 and transitions at its edges into the first annular portion 24, and is thus fluidically connected to the latter. The copper anode 1 is cast by pouring liquid raw copper into the casting mould 7, as has been described in the introduction to the description and as is also shown in relation to an exemplary embodiment in Figure 16.
The copper anode 1 which has been cast in the casting mould 7, which copper anode can be seen in Figure 9, thus has a flat, rectangular anode sheet 10 having an approximately constant thickness in the depiction plane. Two holding arms 2 are moulded as one part onto the upper edge of the anode sheet 10, said holding arms also having an approximately constant thickness in the depiction plane. The holding arms 2 protrude upwards and outwards from the anode plate 10 and respectively form a contact surface 12 on their undersides for contacting the contacts 6 which are in the form of conductor rails (see Figures 3 to 5).

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Due to the shape of the second cavities 9 with the central cores 20, the holding arms 2 respectively 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 on their ends and enclose a recess 11 between them, which is formed in shape by the shape of the core 20. The recesses 11 are closed in the depiction on their rear sides by supporting walls 15, which are formed by the shape of the flat second portions 25 of the second cavities 9. The supporting walls 15 are formed by flat walls which are aligned in parallel with the plane extending through the anode sheet 10. The plane extending through the anode sheet 10 corresponds to the depiction plane and is described in the following only as plane I, which also applies to the subsequent exemplary embodiments.
As can be seen from Fig. 16, the core 20 provided in the second cavity 9 acts to produce the recess 11 as a barrier for the raw copper flowing in when casting the copper anode 1.
The raw copper flowing in is thus pushed to the side of the barrier into the second cavity 9, which in this case is formed as a channel and in an annular shape in a first portion 24, and is formed flat in a second portion 25 for forming the supporting wall 15, corresponding to the edges 13 and 14 to be formed.
The flow of the raw copper is thus slowed and simultaneously homogenised, which leads in turn to a more homogeneous thickness of holding arms 2 of the copper anode 1 after casting. Starting from the first cavity 8, the raw copper flows via the first portion 24 in the form of a channel and simultaneously via the second flat portion 25 on an end face into the second cavity 9.
In the casting mould 7 known in the prior art, which can be seen in Figure 7, there is no core 20, which leads the raw copper to flow unimpeded into the corresponding cavity 9 which is larger in volume, to swing upwards and to solidify to form holding arms 2 of different thicknesses. This effect is avoided by the provided cores 20, and the second cavities 9 are filled with liquid raw copper more evenly and more completely, which then leads the holding arms 2 of the cast copper anode 1 to have a substantially more constant thickness and a more even surface.
The recesses 11 are formed by depressions in the holding arms 2 and additionally reduce the quantity of raw copper poured into the holding arms 2. The exterior dimensions of the holding arms 2 are deliberately not reduced, because a particularly high load-bearing capacity and rigidity of the holding arms 2 can be obtained via correspondingly large exterior dimensions. The lower edge 13 and the upper edge 14 of the holding arms 2 have a substantially constant wall thickness B in the plane I, such that the recess 11 has a scaled-down shape in relation to the exterior shape of the holding arms 2. However, the lower edge 13 can also have a slightly greater wall strength, such that a correspondingly flat contact surface 12 can then be created via milling or sanding of the surface without the load-bearing capacity of the holding arms 2 thus being reduced to such an extent that they can no longer carry out their holding function.
The holding arms 2 are reduced in weight by the recesses 11 and simultaneously stiffened by the supporting walls 15. The supporting walls 15 are aligned in parallel with the plane I of the anode sheet 10, such that they stiffen the holding arms 2 as much as possible against the tensile stresses acting in the plane I. They thus have the required load-bearing capacity for handling and supporting the copper anode 1, while their mass is simultaneously reduced, such that the waste portion of the copper anode 1 is reduced after the electrolysis process with the advantages described above. Due to their arrangement in parallel with the plane I, the supporting walls 15 are aligned in parallel with the gravity acting on the copper anode 1 when lifting the copper anode 1 and when hanging the copper anode 1 in the electrolysis bath, and thus cause a maximum stiffening of the holding arms 2 against the pressing forces exerted via the contact surface 12 when supporting the copper anode 1.
In Figures 10 and 11, a second, further developed exemplary embodiment of the invention can be seen, in which the holding arm 2 which is on the right in the depiction has a recess 11, which is closed on one side in the upper portion by a supporting wall 15. The supporting wall 15 deliberately does not completely cover the recess 11, such that the recess 11 is formed in the lower portion as a through opening 16. The holding arm 2 which is on the left in the depiction is formed according to the holding arms 2 of Figure 9. The right holding arm 2 is thus further reduced in weight by the through opening 16, wherein the dimensions and the shape of the supporting wall 15 can be optimised in shape with regards to the stiffness of the holding arm to be obtained, e.g., in the manner of a finite element calculation. The recess 11 is in turn formed by a core 20 in the second cavity 9 of the casting mould 7, wherein the through opening 16 is formed by the core 20 having a height corresponding to the depth of the second cavity 9, and thus completely sub-divides the second cavity 9 into a first annular portion 24 in the form of a channel without the second portion 25.

In Figures 12 and 13, a further exemplary embodiment can be seen, in which the recesses 11 are completely formed as through openings 16 in both holding arms 2, whereby the weight reduction can be further maximised. The required rigidity of the holding arms 2 is obtained only by the dimensions of the holding arms 2 in their edges 13 and 14, wherein here in particular, the dimensioning of the wall strength B of the edges 13 and 14 is available in the plane I.
In Figures 14 and 15, a further exemplary embodiment of the invention can be seen, in which the recesses 11 in the holding arms 2 are respectively formed by a through opening 16, said through openings respectively being subdivided into two partial through openings 18 and 19 by a stiffening rib 17 in the manner of a framework. In this exemplary embodiment, the stiffening ribs 17 are aligned or arranged such that their longitudinal axes C run approximately in parallel with a longitudinal central axis A of the anode sheet 10. Due to the stiffening ribs 17, the holding arms 2 are stiffened using as little material or additional weight as possible, wherein the alignment in parallel with the longitudinal central axis A is particularly advantageous, because the stiffening rib 17 thus stiffens the holding arms 2 particularly efficiently against pressing forces acting on the contact surface 12. The stiffening ribs 17, however, can also be aligned at an angle of up to 45 degrees in relation to the longitudinal central axis A and still cause an effective stiffening of the holding arms 2.
For this purpose, the core 20 is sub-divided by a gap 21 into two partial cores 22 and 23 in the second cavities 9. The stiffening rib 17 is cast through the gap 21, said stiffening rib separating the partial through openings 18 and 19 formed by the partial cores 22 and 23 from each other.
The decisive advantage of the solution according to the invention is that the weight of the anode waste can be reduced and the efficacy of the electrolysis method in relation to the raw copper used can be very easily increased without sacrificing the advantage of the significantly more cost-efficient manufacture of the copper anode 1 as one part with the anode plate 10 having the holding arms 2. The recesses 11 are deliberately designed as depressions in the holding arms 2, and thus as cavities extending from a flat surface of the holding arms 2 into the holding arms 2, such that a high stiffness of the holding arms 2 caused by the retained exterior shape can be generated while simultaneously reducing the weight of the holding arms 2 via the recesses 11 provided therein. The recesses 11 are deliberately provided in the holding arms 2, such that the quantity of the high-. . .

purity copper to be produced is not reduced, because the holding arms 2 are not destroyed in the electrolysis process and thus do not contribute to the extraction of the high-purity copper.

Claims (15)

Claims:

1. Casting mould (7) for producing copper anodes (1) for producing high-purity copper having - a first flat cavity (8), which is delimited by two lateral surfaces aligned in parallel with each other, and - two second cavities (9), which are fluidically connected to the first cavity are arranged on different corners on a peripheral side of the first cavity (8) and extend laterally outwardly away from the first cavity (9), characterised in that - a core (20) is respectively provided centrally in the second cavities (9), said core sub-dividing the respective second cavity (9) at least partially into a closed annular shape in the peripheral direction.

2. Casting mould (7) according to claim 1, characterised in that - the core (20) completely sub-divides the second cavity (9) into a closed annular shape in the peripheral direction.

3. Casting mould (7) according to claim 1, characterised in that - the core (20) sub-divides the second cavity (9) into a first portion (24) having a closed annular shape and a second flat portion (25), wherein the second flat portion is arranged laterally on the first portion.

4. Casting mould (7) according to one of claims 1 to 3, characterised in that - the core (20) is sub-divided into two partial cores (22, 23) by a gap (21).

5. Casting mould (7) according to claim 4, characterised in that - the gap (21) is aligned at an angle of 0 to 45 degrees to a longitudinal central axis (4) of the first cavity (8).

6. Copper anode (1) for producing high-purity copper, having - an anode sheet (10), and - at least two holding arms (2), wherein - at least one recess (11) is provided in at least one of the holding arms (2), characterised in that - the holding arms (2) are formed as one part with the anode sheet (10).

7. Copper anode (1) according to claim 6, characterised in that - the recess (11) has a shape which corresponds to a scaled-down outer shape of the holding arm (2).

8. Copper anode (1) according to claim 6 or 7, characterised in that - the recess (11) is at least partially closed by a supporting wall (15).

9. Copper anode (1) according to claim 8, characterised in that - the depth of the recess (11) down to the supporting wall (15) corresponds to at least half of the thickness of the holding arm (2) perpendicular to a plane I
extending through the anode sheet (10).

10. Copper anode (1) according to one of claims 6 to 9, characterised in that - the recess (11) is at least partially formed as a through opening (16).

11. Copper anode (1) according to one of claims 6 to 10, characterised in that - the recess (11) is sub-divided into two partial recesses (18, 19) by means of a stiffening rib (17).

12. Copper anode (1) according to claim 11, characterised in that - the stiffening rib (17) is aligned at an angle of 0 degrees to 45 degrees to a central longitudinal axis (A) of the anode sheet (10) running between the holding arms (2).

13. Copper anode (1) according to one of claims 6 to 12, characterised in that - the recess (11) is dimensioned such that the holding arms (2) on their side of the electrical contact surface (12) at least partially have a greater wall strength in a plane I
extending through the anode sheet (10) than on the side which does not have an electrical contact surface (12).

14. Copper anode (1) according to one of claims 6 to 13, characterised in that - the holding arms (2) have a constant thickness with regards to a plane I
extending through the anode sheet (10).

15. Copper anode (1) according to one of claims 6 to 14, characterised in that - the copper anode (1) is cast in a casting mould (7) according to one of claims 1 to 5.