CA2811553A1 - Electrolytic cell for extracting aluminium - Google Patents
Electrolytic cell for extracting aluminium Download PDFInfo
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- CA2811553A1 CA2811553A1 CA2811553A CA2811553A CA2811553A1 CA 2811553 A1 CA2811553 A1 CA 2811553A1 CA 2811553 A CA2811553 A CA 2811553A CA 2811553 A CA2811553 A CA 2811553A CA 2811553 A1 CA2811553 A1 CA 2811553A1
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- electrolytic cell
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
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- Chemical Kinetics & Catalysis (AREA)
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- Materials Engineering (AREA)
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- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention relates to an electrolysis cell for extracting aluminium from its oxide, comprising a cathode (1) and at least one lateral wall (1a), which together define a basin (1c). At least one raised part (1d) is formed inside the basin (1c), extending from the cathode (1) or a lateral wall (1a) into the basin (1c).
Description
1 14.03.2013 Electrolytic cell for extracting aluminium The invention relates to a cathode for an electrolytic cell for extracting aluminium by fused-salt electrolysis.
The Hall-Heroult process is currently used for the industrial extraction of aluminium from its oxide. This is an electrolytic process in which aluminium oxide (A1203) is dissolved in molten cryolite (Na3 [AlF61) and the resulting mixture acts as a liquid electrolyte in an electrolytic cell. In principal, the design of this sort of electrolytic cell used to carry out the Hall-Heroult process is depicted schematically in Figures la to 1 c, wherein Figure la shows a cross-section through a traditional cell, while Figure lb shows an external side view of the cell. Fig. 1 c shows a perspective view of an electrolytic cell.
Reference symbol 1 denotes a cathode, which may, for example, be made from graphite, anthracite or a mixture of these. Alternatively, coke-based graphitised cathodes may also be used. The cathode 1 is generally embedded in a mounting 2 made from steel and/or a fire-resistant material or the like.
The cathode 1 may be made in one-piece as well as may be made from individual cathode blocks.
Over the entire length of the cell, a number of current supply bars 3 are introduced into the cathode 1, although only a single current supply bar 3 can be seen in the cross-sectional view in Figure la. It can be seen in Fig. lc that two current supply bars, for example, may be provided for each cathode block. The current supply bars are used to supply the cell with the current required for the electrolytic process. There is a plurality of typically prismatic anodes 4 opposite the cathode 1, wherein two anodes 4 are schematically depicted in Figure 1 a. Fig. 1 c shows a detailed configuration of anodes in an electrolytic cell. During the performance of the process, the aluminium oxide dissolved in cryolite is split into aluminium ions and oxygen ions, in which case the aluminium ions move to the molten aluminium ¨ actually the cathode from an electrochemical point of view ¨ where they accept electrons by applying a voltage between cathode 1 and anodes 4. Due to the greater SGL CARBON SE
=
The Hall-Heroult process is currently used for the industrial extraction of aluminium from its oxide. This is an electrolytic process in which aluminium oxide (A1203) is dissolved in molten cryolite (Na3 [AlF61) and the resulting mixture acts as a liquid electrolyte in an electrolytic cell. In principal, the design of this sort of electrolytic cell used to carry out the Hall-Heroult process is depicted schematically in Figures la to 1 c, wherein Figure la shows a cross-section through a traditional cell, while Figure lb shows an external side view of the cell. Fig. 1 c shows a perspective view of an electrolytic cell.
Reference symbol 1 denotes a cathode, which may, for example, be made from graphite, anthracite or a mixture of these. Alternatively, coke-based graphitised cathodes may also be used. The cathode 1 is generally embedded in a mounting 2 made from steel and/or a fire-resistant material or the like.
The cathode 1 may be made in one-piece as well as may be made from individual cathode blocks.
Over the entire length of the cell, a number of current supply bars 3 are introduced into the cathode 1, although only a single current supply bar 3 can be seen in the cross-sectional view in Figure la. It can be seen in Fig. lc that two current supply bars, for example, may be provided for each cathode block. The current supply bars are used to supply the cell with the current required for the electrolytic process. There is a plurality of typically prismatic anodes 4 opposite the cathode 1, wherein two anodes 4 are schematically depicted in Figure 1 a. Fig. 1 c shows a detailed configuration of anodes in an electrolytic cell. During the performance of the process, the aluminium oxide dissolved in cryolite is split into aluminium ions and oxygen ions, in which case the aluminium ions move to the molten aluminium ¨ actually the cathode from an electrochemical point of view ¨ where they accept electrons by applying a voltage between cathode 1 and anodes 4. Due to the greater SGL CARBON SE
=
14.03.2013 density, aluminium 5 gathers in the liquid phase beneath the molten mixture 6 of aluminium oxide and cryolite. The oxygen ions are reduced to oxygen at the anode, said oxygen reacting with the carbon of the anodes.
Reference symbols 7 and 8 are the schematic representations of the negative and positive poles, respectively, of a voltage source for supplying the voltage required for the electrolytic process, the value of which lies between approximately 3.5 and 5 V, for example.
As can be seen in the side view in Figure lb, the mounting 2 and therefore the entire electrolytic cell has an elongated form, in which a plurality of current supply bars 3 are conducted horizontally through the side walls of the mounting 2. The longitudinal expansion of cells currently in use is typically between approximately 8 and 15 m, while the width expansion is approximately 3 to 4 m. A cathode, as is shown here in Figure 1a, is disclosed in EP 1845174, for example.
The current intensities used today in the fused-salt electrolysis process of up to 600 kA cause a high energy requirement. The associated costs constitute the bulk of the process costs involved in the fused-salt electrolysis described.
Reducing these costs is one of the major problems that must be overcome in the field of fused-salt electrolysis.
One determining factor for energy consumption is the required distance between the anode surfaces and the liquid aluminium in the electrolytic cell.
The anode or anodes must be spaced far enough away from the surface of the aluminium to prevent a short-circuit between the anodes and the cathode blocks across the aluminium. The anodes may theoretically be brought very close to the surface of the liquid aluminium, provided it is smooth. However, due to the high currents introduced into the cathode through the current supply bars during fused-salt electrolysis, electromagnetic fields are produced, which induce currents and wave movements in the liquid aluminium due to their interactions.
Reference symbols 7 and 8 are the schematic representations of the negative and positive poles, respectively, of a voltage source for supplying the voltage required for the electrolytic process, the value of which lies between approximately 3.5 and 5 V, for example.
As can be seen in the side view in Figure lb, the mounting 2 and therefore the entire electrolytic cell has an elongated form, in which a plurality of current supply bars 3 are conducted horizontally through the side walls of the mounting 2. The longitudinal expansion of cells currently in use is typically between approximately 8 and 15 m, while the width expansion is approximately 3 to 4 m. A cathode, as is shown here in Figure 1a, is disclosed in EP 1845174, for example.
The current intensities used today in the fused-salt electrolysis process of up to 600 kA cause a high energy requirement. The associated costs constitute the bulk of the process costs involved in the fused-salt electrolysis described.
Reducing these costs is one of the major problems that must be overcome in the field of fused-salt electrolysis.
One determining factor for energy consumption is the required distance between the anode surfaces and the liquid aluminium in the electrolytic cell.
The anode or anodes must be spaced far enough away from the surface of the aluminium to prevent a short-circuit between the anodes and the cathode blocks across the aluminium. The anodes may theoretically be brought very close to the surface of the liquid aluminium, provided it is smooth. However, due to the high currents introduced into the cathode through the current supply bars during fused-salt electrolysis, electromagnetic fields are produced, which induce currents and wave movements in the liquid aluminium due to their interactions.
3 14.03.2013 These wave movements mean that a greater safety distance must be maintained for the anode(s) compared with a smooth aluminium surface, in order to prevent short-circuits and the unwanted back reaction (oxidation) of the aluminium into aluminium oxide. In addition, wave movements cause greater wear to the cathode locally, whereby the service life of the entire electrolytic cell is reduced.
One problem addressed by the invention is therefore to specify an electrolytic cell used to extract aluminium, with which the wave formation described can be reduced during fused-salt electrolysis.
This problem is solved according to the invention by an electrolytic cell with the features of claim 1. Preferred embodiments are specified in the dependent claims.
In accordance with the embodiments of the invention, an electrolytic cell used to extract aluminium from its oxide exhibits a cathode and at least one side wall, which together bound a tank, wherein at least one projection is formed within the tank, which extends from the cathode or a side wall into the tank.
Within the meaning of the invention, the term "cathode" is interpreted quite generally. It may be, for example (although not exclusively), a so-called cathode bottom, which is made from a plurality of cathode blocks, so that the core aspects according to the invention ¨ namely, the formation of projections described above ¨ are realised as a whole by this cathode bottom. However, the term cathode is also intended to refer to the partial structures forming such a cathode bottom, as in cathode blocks. All features that may contribute to the invention in connection with a "cathode" do so in the same way in connection with a "cathode block", without this having to be expressly explained below in each case.
The at least one projection acts as a kind of wave-breaker in this case, which reduces the wave movement and thereby contributes to smooth the surface of the liquid aluminium. In other words, the at least one projection represents a = SGL CARBON
One problem addressed by the invention is therefore to specify an electrolytic cell used to extract aluminium, with which the wave formation described can be reduced during fused-salt electrolysis.
This problem is solved according to the invention by an electrolytic cell with the features of claim 1. Preferred embodiments are specified in the dependent claims.
In accordance with the embodiments of the invention, an electrolytic cell used to extract aluminium from its oxide exhibits a cathode and at least one side wall, which together bound a tank, wherein at least one projection is formed within the tank, which extends from the cathode or a side wall into the tank.
Within the meaning of the invention, the term "cathode" is interpreted quite generally. It may be, for example (although not exclusively), a so-called cathode bottom, which is made from a plurality of cathode blocks, so that the core aspects according to the invention ¨ namely, the formation of projections described above ¨ are realised as a whole by this cathode bottom. However, the term cathode is also intended to refer to the partial structures forming such a cathode bottom, as in cathode blocks. All features that may contribute to the invention in connection with a "cathode" do so in the same way in connection with a "cathode block", without this having to be expressly explained below in each case.
The at least one projection acts as a kind of wave-breaker in this case, which reduces the wave movement and thereby contributes to smooth the surface of the liquid aluminium. In other words, the at least one projection represents a = SGL CARBON
4 14.03.2013 deliberate obstacle intended to influence the liquid flow inside the cathode tank in terms of an absorption or restraint.
Since the molten aluminium inside the cathode tank can be smoothed by means of the projection(s), it is possible for the anode of an electrolytic cell, which is formed according to embodiments of the invention, to be brought closer to the surface of the liquid aluminium, so that the energetic efficiency of the electrolytic cell can be increased. Specific energy costs can be significantly reduced in this way. The reduction in the anode/cathode distance or, more accurately, the distance between the anodes and the liquid aluminium, can also be used to increase the current intensity and thereby improve the productivity of the electrolytic cell. In addition, the wearing of cathode material due to mechanical influences (abrasion), which is caused by liquid movement, is reduced. A longer service life can thereby be achieved for the cathode.
In relation to the size and position of the projection or projections, this depends at least in part on the specific geometry of the electrolytic cell's tank and also the nature of the current supply to the electrolytic cell's cathode.
For what is a customary cell at present with a length of between approximately 8 and 15 m and a width of approximately 3 to 4 m, it has proved to be suitable for the at least one projection to extend beyond the traditional cathode surface by approximately 5 cm and 50 cm.
In an exemplary embodiment of the electrolytic cell there are several projections disposed at intervals from one another. This means that the flow disruption function can be shared between several projections, so that a greater homogeneity of the liquid in relation to its movement can be achieved.
The projections may generally run from the cathode or from the at least one side wall towards the centre of the electrolytic cell or extend into the tank.
An anchoring close to one of the two walls may be advantageous. With regard to the reliable suppression of wave movements in the liquid aluminium, it has proved to be favourable if the at least one projection extends from one side = SGL CARBON
14.03.2013 into the inside of the tank.
With the electrolytic cells customary at present, in which the tank has a rectangular form when viewed from above with a side wall on every side, projections are preferably provided on both side walls, which protrude into the inside of the tank. A symmetrical configuration with regard to the longitudinal axis of the electrolytic cell has a positive effect on homogeneity within the liquid. Furthermore, it is possible for the projections to be designed in such a way that a lower edge, in other words, the edge closest to the cathode, is spaced away from the cathode.
However, it has been demonstrated in the context of the invention that a configuration with projections at irregular intervals may, surprisingly, also prove to be advantageous, particularly in suppressing wave movements in the liquid aluminium.
The cathode and/or the at least one side wall is frequently not formed from a single block but is made up of several components that are connected to one another by a ramming mass or glue. The at least one side wall may therefore consist of several side wall blocks, the cathode of several cathode blocks. In this design, glued or rammed seams, for example, extend between the cathode blocks and/or the side wall blocks. The ramming masses are generally made from a mixture of carbon grain and coal tar or coal tar pitch, which is introduced between the blocks in highly compressed form by ramming, in order to seal the gaps.
In accordance with one embodiment of the invention, the ramming masses may act as a support for the projection(s) at the cathode and/or at the side wall. This involves the at least one projection being held at one end by the ramming mass in a ramming seam. This embodiment is particularly advantageous from a production point of view, as the projections can be integrated as part of the seam sealing production step. In this case, no additional support and no additional gluing agent are required to secure the projection to the cathode and/or side wall.
' SGL CARBON SE
14.03.2013 In the interests of the symmetry and homogeneity already mentioned, it is favourable with the aforementioned embodiment for a projection to be held in each of the seams between the side wall blocks and/or the cathode blocks.
In relation to the further dimensions of the at least one projection, this may for example advantageously extend to a depth of between approximately 5 cm and approximately 50 cm inside the tank, particularly between approximately and 20 cm. In the context of the invention, the expression "deep" relates to a dimension perpendicular to the side wall from which the projection extends in each case and parallel to the base wall. In an electrolytic cell with a rectangular tank, this is the direction from the side wall to the longitudinal axis or the lateral axis of the cathode, in a circular electrolytic cell it corresponds to the radial direction. The aforementioned depth range has proved adequate for the reliable absorption of the wave movement in a cathode tank of the aforementioned size.
In accordance with an embodiment of the invention, the at least one projection may exhibit a rectangular form with rounded edges in cross-section. In this case the rounded edges help suppress the emergence of eddies in the liquid aluminium. Alternatively, the design may be executed in chamfered form to allow emerging waves to "run aground" (see Fig. 4).
The at least one projection may be made from carbon or graphite, for example. Material combinations, particularly graphite or carbonic composite materials, such as CFC (carbon fibre-reinforced carbon) materials, for example, or sheets or foils made from compressed or partially compressed expanded graphite may also be advantageous. This means that the material of the at least one projection is similar to that of the cathode itself. In this way, the fused-salt electrolysis process or chemical conditions inside the cathode are not interfered with. In terms of minimising any influence on the current path in the cathode, the at least one projection may advantageously exhibit a lower electrical conductivity than the cathode and/or side walls.
It may be advantageous for the projections to exhibit a layer composition. A
7 14.03.2013 layer composition of this kind may be accomplished using the aforementioned materials, for example. In particular, a middle layer may contain a CFC
material or be made from this and outer layers may contain compressed, expanded graphite. Material combinations of this kind mean that mechanical stresses and chemical loads can be faced particularly effectively.
It may furthermore be advantageous for the outer layers not to project beyond the seam or barely to do so, so that the projection extending into the inside of the tank is formed at least basically from a middle layer, while the outer layers assume the function of holding the middle layer in the seam. Hence, a CFC
layer, which projects into the inside of the tank, is held in the seam by compressed expanded graphite or carbonaceous ramming mass as the outer layers.
In a further embodiment, it may be advantageous for the at least one projection to be provided as a detachable projection. A detachable projection in the context of the invention refers to a projection that is not connected to a cathode and/or a side wall by a material connection, but by a device that permits detaching. Instead of this, a material connection would be the already mentioned integration in a ramming mass or a projection manufactured in one piece together with a cathode or side wall block. In contrast, the embodiment of the detachable projection involves a connection in which the connection between the projection and cathode and/or side wall is mechanical in nature.
These connections may be detached again, at least in an assembly state in which there has not yet been any chemical or mechanical destruction due to the cell operation.
The at least one detachable projection is preferably formed as a screw-in projection. To this end, a projection is provided that can be attached to the cathode and/or a side wall by means of at least one thread unit or is attached to the latter during use. In the interests of simplicity, the thread unit is referred to in the following simply as "screw".
The screw may be advantageously formed in one piece with the projection.
8 14.03.2013 The advantage of this is that the mechanical connection of the screw to the projection is particularly rigid.
Alternatively, the screw may be advantageously designed separate from the projection. This means that the screw and projection can be produced with limited technical effort and therefore cost-effectively. Furthermore, the at least one projection can be secured to the cathode and/or side wall with at least two screws where the projection and screw are formed separately. The advantage of this is that a projection can be positioned particularly specifically in relation to a possible alignment of the projection relative to the electrolytic cell.
Moreover, particularly secure mechanical connections can be achieved.
It may be advantageous for the screw to be provided in the same material as the projection and/or the cathode and/or side wall to be screwed to the projection. The same material is advantageous particularly with regard to thermal expansion behaviour, as mechanical stresses can thereby be avoided. This also means that the screw and projection and/or the cathode or side wall will have a similar corrosive behaviour.
The screw thread may be formed in various preferred ways. That section of the thread disposed within the projection during use is referred to below as the upper section and that section of the thread disposed within the cathode or a side wall during use is referred to as the base section.
The base section is preferably conical in design. This makes it easier for the screw or the projection along with the screw to be screwed into the cathode or side wall.
Where the screw and projection are formed in one piece, the upper section is completely in one piece within the projection.
In the separate variant of screw and projection, it may be advantageous for the upper section to be conical in form. This is advantageous for a quick and easy screw connection of the projection.
9 14.03.2013 In one variant, the upper section has a cylindrical thread. This may be advantageous in minimising the emergence of mechanical stresses. In this variant, the projection may advantageously exhibit a through-hole thread to hold a screw. This enables the screw to be screwed in through the projection into a cathode or side wall by means of a screwing device, such as a traditional screwdriver. By means of a corresponding configuration of threaded holes in the cathode and/or side wall, precise positions of firmly screwed projections can be achieved, particularly when there are at least two holes per projection.
The base section and upper section may exhibit further desired thread geometries, depending on need, accessibility of the screw site within the electrolytic cell and other conditions, such as the processing properties of the screw material too.
The threaded holes required for a screw connection can be both incorporated in cathode blocks, side wall blocks and projections during their production and also in an electrolytic cell on site. Incorporation during production itself has the advantage of a precise method of operation. Efficient production methods can be used. On-site incorporation has the advantage of great flexibility. So, for instance, electrolytic cells can be selectively retrofitted with projections, as required.
Further suitable detachable connections may be tensioning and/or clamping connections, such as clamping pieces, spiral tappets, slip tongue joints and similar mechanical connections. Rather than the aforementioned threaded holes for the arrangement of projections, corresponding structuring, holes or similar are provided in the cathode or side wall blocks, to secure these connections detachably at predetermined points on the cathode and/or side wall blocks.
The materials of the detachable connections are preferably the same materials used for the projections and/or the cathode or side wall blocks = SGL CARBON
14.03.2013 themselves. Alternatively, other traditional materials resistant to the working temperature and chemical influences included in the group of carbon or graphite products or ceramics or other known high-temperature materials are conceivable.
The desired positions and alignments of the projections can be determined empirically or through simulation calculations.
The invention will now be described in greater detail with reference to the attached drawing using a non-restrictive exemplary embodiment. In the drawing:
Fig. la shows a schematic cross section of an electrolytic cell for the extraction of aluminium oxide according to the state of the art, Fig. lb shows the electrolytic cell from Fig. 1 a in an external longitudinal view, Fig. lc shows a perspective view partially in section of an electrolytic cell for the extraction of aluminium from aluminium oxide according to the state of the art, Fig. 2 shows a perspective view of a section of an electrolytic cell according to an embodiment of the invention, Fig. 3 shows a perspective view of a section of an electrolytic cell according to an alternative embodiment of the invention, Fig. 4 shows the cross-section of projections according to the invention, Fig. 5 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, ' SGL CARBON SE
14.03.2013 Fig. 6 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, Fig. 7 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, Fig. 8 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, Fig. 9a shows a top view and a sectional view of a screw-in projection, Fig. 9b shows a sectional view of an alternative embodiment of a screw-in projection, Fig. 9c shows a perspective view of a further alternative embodiment of a screw-in projection, Fig. 10a shows a perspective view of a screw for a screw-in projection in accordance with Fig. 9c, and Fig. 10b shows a perspective view of an alternative embodiment of a screw for a screw-in projection according to Fig. 9c.
The same reference symbols are used in the figures to refer to the same or corresponding elements in the different representations.
With reference to Figure 2, an embodiment of an electrolytic cell according to the invention is shown as a perspective view, denoted in its entirety by the reference symbol 100. The cathode 1 and side wall 1a shown here are suitable for use in an electrolytic cell, as depicted in Figures la to 1c, instead of the cathode 1 and the side wall la shown there.
As can be seen, the side wall la in this exemplary embodiment is not formed " SGL CARBON SE 2010/052W0 12 14.03.2013 in one piece, but comprises two side walls la running parallel to one another, which are made up of individual side wall blocks 1a1 . In a similar way, a cathode 1 is made up of several cathode blocks 1b1. The side walls 1a and the cathode 1 together bound a tank 1c. Side walls on the narrow ends of the tank (parallel to the image plane of Figure 2) are not shown in the figure.
This tank construction corresponds to a cathode design customary at present. The embodiment of the electrolytic cell 100 shown here is not obligatory, however.
Likewise, the cathode tank may, for example, be round or square in shape.
What is essential in the context of the invention is that projections ld protrude into the tank lc of the electrolytic cell 100, which may extend from the cathode 1 and/or from the side wall 1a or the side walls 1a. In the embodiment shown, several projections 1d exist, which are attached to the cathode 1 (perpendicular to the image plane of Figure 2) in a longitudinal direction spaced at equal intervals relative to one another. Although only three projections 1d are shown on the left side wall la in the diagram, it should be noted that it is advisable in the interests of symmetry for projections 1d to be formed on both side walls. In the example shown, no projections were shown on the right side, simply in the interests of making the figure clear.
As can be seen, the projections 1d are each positioned in the area of the seams, so-called "ramming seams" le, which are so called because during assembly of the cathode 1 from cathode blocks 1a1 and the side wall 1a from side wall blocks 1a1, these seams are sealed by ramming with a mass, which is similarly referred to as a ramming mass if. The ramming mass if not only acts as a sealing agent in the example shown, but at the same time serves to secure the projections 1d in the area of the side walls la. During production of the cathode 1, the projections 1d may be rammed from the top along with the ramming mass If into the ramming seams le, in such a way that they are held at one end in the respective seam le, as shown, while a second end projects into the inside of the tank 1c. In the example shown, the projections 1d are directed from the side wall la in each case towards the cathode's longitudinal axis L. If, as is traditionally the case, the side wall blocks are not joined by ramming, the projections are fixed in the seams between the side wall blocks 13 14.03.2013 with ramming mass or glue, for example.
As can further be seen, a lower edge 1d1 of the respective projections 1d is not parallel to the cathode 1, but is tilted relative to the same. This means there is a wedge-shaped gap between the cathode 1 and the projection 1d, which means that when liquid aluminium is used, it can also flow under the projection 1d. This may be advantageous from a flow point of view.
Fig. 3 shows a modification of the exemplary embodiment, in which projections 1d protrude into the inside of the tank 1c from the cathode blocks 1b1 rather than from the side wall la. In this variant the projections 1d are disposed offset in pairs relative to one another, which may be advantageous to the selective influencing of flow conditions.
The projections 1d may be moulded bodies preferably made from anthracite, graphite or another carbon material. The material used for the projections 1d advantageously has a lower electrical conductivity than that of the cathode 1 or side walls la. In addition, it is advantageous for the material to exhibit a high resistance to mechanical wear (abrasion), so that the projections 1d preferably exhibit at least the same service life as the cathode 1 itself, so that they do not have to be renewed more frequently than the cathode 1 and/or side walls la of the electrolytic cell. Alternatively, CFC materials or panels and foils made from compressed, expanded graphite, for example, may be used for the projections 1d.
It may be advantageous for the projections to exhibit a layer composition. A
layer composition of this kind may, for example, be accomplished with the aforementioned materials. In particular, a middle layer may contain a CFC
material or be made from this and outer layers may contain compressed expanded graphite. Mechanical stresses and chemical loads can be particularly effectively resisted by material combinations of this kind.
It may furthermore be advantageous for the outer layers not to jut out or to barely jut out beyond the seam, so that the projection jutting into the inside of . SGL CARBON SE
14.03.2013 the tank is formed at least essentially from the middle layer, while the outer layers assume the function of holding the middle layer in the seam. Hence, a CFC layer that juts into the inside of the tank may be held in the seam by compressed, expanded graphite or a carbonaceous ramming mass as outer layers.
The configuration shown here and the form of the projections should only be regarded as a non-restrictive example. This involves a cathode, which can be used in connection with the electrolytic cell shown in Figures la to 1 c, in which the current is conducted in the cathode area through current supply bars 3 parallel to the cathode blocks lbl of the cathode 1. However, embodiments are also conceivable in principle in which the current supply is in a vertical direction perpendicular to an underside of the cathode 1. The most suitable configuration of cathode projections in each specific embodiment of electrolytic cells may simply be determined by considering the main areas of increased wear of the cathode concerned. The person skilled in the art will then easily be able to determine suitable positions and forms for the projections Id, taking account of the fluid dynamics. Examples of advantageous projections are shown in cross-section in Fig. 4.
In accordance with an alternative variant of the exemplary embodiment, rather than being disposed in the seams le, the projections are screwed to the cathode 1 or the side wall blocks lal.
Projections id are used for this, as are depicted, for example, in Figures 9a and 9b. In a first variant, projections id are provided in one piece with a thread unit 9 (Fig. 9a), in which case only a base section 10 extends from the projection id.
In a second variant, which is depicted in Fig. 9b, the thread unit 9 is produced separately from the projection and its upper section 11 is screwed with its thread 12 into a matching mating thread in the projection id. In both variants the screw-in projections id can be screwed into side wall blocks lal, as shown in Fig. 5.
15 14.03.2013 In a further variant of the screw-in projection 1d, which is depicted in Fig.
9c, the at least one projection 1d is provided with two threaded through-holes.
Screws 9 are screwed into the through-holes, which can be screwed by means of a slot 13 and a matching screwing tool (not shown) into the mating thread of the cathode 1, for example. Fig. 9c shows screws 9, which have a cylindrical geometry in their upper section 11, but have a base section 10, which is screwed into the cathode 1, which is conically formed. The screw 9 is also depicted alone in Fig. 10a.
Fig. 10b shows a variant of the screw 9 exhibiting a single, continuous conical thread in the upper section 14 and the base section 15.
Figures 6 to 8 show how, particularly with this kind of double screw connection, a multiplicity of positions and alignments of projections 1d is possible in the electrolytic cell 100.
In Fig. 6 projections 1d of varying size are disposed at right angles to the cathode base, but at irregular intervals from the side wall la.
In Fig. 7 projections 1d are screwed at an slanting setting angle to the side wall blocks 1a1.
In Fig. 8 projections 1d, similar as in Fig. 7, are screwed to the cathode at slanting angles instead of the side wall 1.
The exact positions and angles are optimised depending on the prevailing flow profile within the electrolytic cell by computer simulation. The positions of several projections are not necessarily evenly distributed symmetrically within the electrolytic cell or in the individual cathode blocks in each case.
Individual positions of this kind may be achieved by tapping in the otherwise finished electrolytic cell, for example.
In relation to the cathode materials, any materials known to the person skilled in the art and suitable for the electrolysis of aluminium from aluminium oxide 16 14.03.2013 may be used. Suitable materials are specified in DE 10261745, for example, the content of which, in this respect, is to be incorporated here by reference.
Graphite has proved to be particularly favourable in this respect, due to its temperature resistance and due to its low specific electrical resistance.
With an electrolytic cell according to embodiments of the invention, the power loss of the same during the performance of fused-salt electrolysis to extract aluminium through suppression of the wave formation in the produced aluminium melt can be significantly reduced. Moreover, the mechanical wear of the cathode is also reduced, as the liquid movements of the aluminium are reduced.
' . SGL CARBON SE
14.03.2013 Reference list 1 Cathode 1a Side wall 1a 1 Side wall block 1b1 Cathode block 1c Tank 1d Projection le Ramming seams if Ramming mass 2 Mounting 3 Current supply bars 4 Anode Aluminium 6 Mixture (aluminium oxide, cryolite) 6a Crust of solidified mixture 6 7 Negative pole, voltage source 8 Positive pole, voltage source 9 Thread unit, screw Base sector of the screw 11 Upper section of the screw 12 Thread 13 Slot 100 Electrolytic cell
Since the molten aluminium inside the cathode tank can be smoothed by means of the projection(s), it is possible for the anode of an electrolytic cell, which is formed according to embodiments of the invention, to be brought closer to the surface of the liquid aluminium, so that the energetic efficiency of the electrolytic cell can be increased. Specific energy costs can be significantly reduced in this way. The reduction in the anode/cathode distance or, more accurately, the distance between the anodes and the liquid aluminium, can also be used to increase the current intensity and thereby improve the productivity of the electrolytic cell. In addition, the wearing of cathode material due to mechanical influences (abrasion), which is caused by liquid movement, is reduced. A longer service life can thereby be achieved for the cathode.
In relation to the size and position of the projection or projections, this depends at least in part on the specific geometry of the electrolytic cell's tank and also the nature of the current supply to the electrolytic cell's cathode.
For what is a customary cell at present with a length of between approximately 8 and 15 m and a width of approximately 3 to 4 m, it has proved to be suitable for the at least one projection to extend beyond the traditional cathode surface by approximately 5 cm and 50 cm.
In an exemplary embodiment of the electrolytic cell there are several projections disposed at intervals from one another. This means that the flow disruption function can be shared between several projections, so that a greater homogeneity of the liquid in relation to its movement can be achieved.
The projections may generally run from the cathode or from the at least one side wall towards the centre of the electrolytic cell or extend into the tank.
An anchoring close to one of the two walls may be advantageous. With regard to the reliable suppression of wave movements in the liquid aluminium, it has proved to be favourable if the at least one projection extends from one side = SGL CARBON
14.03.2013 into the inside of the tank.
With the electrolytic cells customary at present, in which the tank has a rectangular form when viewed from above with a side wall on every side, projections are preferably provided on both side walls, which protrude into the inside of the tank. A symmetrical configuration with regard to the longitudinal axis of the electrolytic cell has a positive effect on homogeneity within the liquid. Furthermore, it is possible for the projections to be designed in such a way that a lower edge, in other words, the edge closest to the cathode, is spaced away from the cathode.
However, it has been demonstrated in the context of the invention that a configuration with projections at irregular intervals may, surprisingly, also prove to be advantageous, particularly in suppressing wave movements in the liquid aluminium.
The cathode and/or the at least one side wall is frequently not formed from a single block but is made up of several components that are connected to one another by a ramming mass or glue. The at least one side wall may therefore consist of several side wall blocks, the cathode of several cathode blocks. In this design, glued or rammed seams, for example, extend between the cathode blocks and/or the side wall blocks. The ramming masses are generally made from a mixture of carbon grain and coal tar or coal tar pitch, which is introduced between the blocks in highly compressed form by ramming, in order to seal the gaps.
In accordance with one embodiment of the invention, the ramming masses may act as a support for the projection(s) at the cathode and/or at the side wall. This involves the at least one projection being held at one end by the ramming mass in a ramming seam. This embodiment is particularly advantageous from a production point of view, as the projections can be integrated as part of the seam sealing production step. In this case, no additional support and no additional gluing agent are required to secure the projection to the cathode and/or side wall.
' SGL CARBON SE
14.03.2013 In the interests of the symmetry and homogeneity already mentioned, it is favourable with the aforementioned embodiment for a projection to be held in each of the seams between the side wall blocks and/or the cathode blocks.
In relation to the further dimensions of the at least one projection, this may for example advantageously extend to a depth of between approximately 5 cm and approximately 50 cm inside the tank, particularly between approximately and 20 cm. In the context of the invention, the expression "deep" relates to a dimension perpendicular to the side wall from which the projection extends in each case and parallel to the base wall. In an electrolytic cell with a rectangular tank, this is the direction from the side wall to the longitudinal axis or the lateral axis of the cathode, in a circular electrolytic cell it corresponds to the radial direction. The aforementioned depth range has proved adequate for the reliable absorption of the wave movement in a cathode tank of the aforementioned size.
In accordance with an embodiment of the invention, the at least one projection may exhibit a rectangular form with rounded edges in cross-section. In this case the rounded edges help suppress the emergence of eddies in the liquid aluminium. Alternatively, the design may be executed in chamfered form to allow emerging waves to "run aground" (see Fig. 4).
The at least one projection may be made from carbon or graphite, for example. Material combinations, particularly graphite or carbonic composite materials, such as CFC (carbon fibre-reinforced carbon) materials, for example, or sheets or foils made from compressed or partially compressed expanded graphite may also be advantageous. This means that the material of the at least one projection is similar to that of the cathode itself. In this way, the fused-salt electrolysis process or chemical conditions inside the cathode are not interfered with. In terms of minimising any influence on the current path in the cathode, the at least one projection may advantageously exhibit a lower electrical conductivity than the cathode and/or side walls.
It may be advantageous for the projections to exhibit a layer composition. A
7 14.03.2013 layer composition of this kind may be accomplished using the aforementioned materials, for example. In particular, a middle layer may contain a CFC
material or be made from this and outer layers may contain compressed, expanded graphite. Material combinations of this kind mean that mechanical stresses and chemical loads can be faced particularly effectively.
It may furthermore be advantageous for the outer layers not to project beyond the seam or barely to do so, so that the projection extending into the inside of the tank is formed at least basically from a middle layer, while the outer layers assume the function of holding the middle layer in the seam. Hence, a CFC
layer, which projects into the inside of the tank, is held in the seam by compressed expanded graphite or carbonaceous ramming mass as the outer layers.
In a further embodiment, it may be advantageous for the at least one projection to be provided as a detachable projection. A detachable projection in the context of the invention refers to a projection that is not connected to a cathode and/or a side wall by a material connection, but by a device that permits detaching. Instead of this, a material connection would be the already mentioned integration in a ramming mass or a projection manufactured in one piece together with a cathode or side wall block. In contrast, the embodiment of the detachable projection involves a connection in which the connection between the projection and cathode and/or side wall is mechanical in nature.
These connections may be detached again, at least in an assembly state in which there has not yet been any chemical or mechanical destruction due to the cell operation.
The at least one detachable projection is preferably formed as a screw-in projection. To this end, a projection is provided that can be attached to the cathode and/or a side wall by means of at least one thread unit or is attached to the latter during use. In the interests of simplicity, the thread unit is referred to in the following simply as "screw".
The screw may be advantageously formed in one piece with the projection.
8 14.03.2013 The advantage of this is that the mechanical connection of the screw to the projection is particularly rigid.
Alternatively, the screw may be advantageously designed separate from the projection. This means that the screw and projection can be produced with limited technical effort and therefore cost-effectively. Furthermore, the at least one projection can be secured to the cathode and/or side wall with at least two screws where the projection and screw are formed separately. The advantage of this is that a projection can be positioned particularly specifically in relation to a possible alignment of the projection relative to the electrolytic cell.
Moreover, particularly secure mechanical connections can be achieved.
It may be advantageous for the screw to be provided in the same material as the projection and/or the cathode and/or side wall to be screwed to the projection. The same material is advantageous particularly with regard to thermal expansion behaviour, as mechanical stresses can thereby be avoided. This also means that the screw and projection and/or the cathode or side wall will have a similar corrosive behaviour.
The screw thread may be formed in various preferred ways. That section of the thread disposed within the projection during use is referred to below as the upper section and that section of the thread disposed within the cathode or a side wall during use is referred to as the base section.
The base section is preferably conical in design. This makes it easier for the screw or the projection along with the screw to be screwed into the cathode or side wall.
Where the screw and projection are formed in one piece, the upper section is completely in one piece within the projection.
In the separate variant of screw and projection, it may be advantageous for the upper section to be conical in form. This is advantageous for a quick and easy screw connection of the projection.
9 14.03.2013 In one variant, the upper section has a cylindrical thread. This may be advantageous in minimising the emergence of mechanical stresses. In this variant, the projection may advantageously exhibit a through-hole thread to hold a screw. This enables the screw to be screwed in through the projection into a cathode or side wall by means of a screwing device, such as a traditional screwdriver. By means of a corresponding configuration of threaded holes in the cathode and/or side wall, precise positions of firmly screwed projections can be achieved, particularly when there are at least two holes per projection.
The base section and upper section may exhibit further desired thread geometries, depending on need, accessibility of the screw site within the electrolytic cell and other conditions, such as the processing properties of the screw material too.
The threaded holes required for a screw connection can be both incorporated in cathode blocks, side wall blocks and projections during their production and also in an electrolytic cell on site. Incorporation during production itself has the advantage of a precise method of operation. Efficient production methods can be used. On-site incorporation has the advantage of great flexibility. So, for instance, electrolytic cells can be selectively retrofitted with projections, as required.
Further suitable detachable connections may be tensioning and/or clamping connections, such as clamping pieces, spiral tappets, slip tongue joints and similar mechanical connections. Rather than the aforementioned threaded holes for the arrangement of projections, corresponding structuring, holes or similar are provided in the cathode or side wall blocks, to secure these connections detachably at predetermined points on the cathode and/or side wall blocks.
The materials of the detachable connections are preferably the same materials used for the projections and/or the cathode or side wall blocks = SGL CARBON
14.03.2013 themselves. Alternatively, other traditional materials resistant to the working temperature and chemical influences included in the group of carbon or graphite products or ceramics or other known high-temperature materials are conceivable.
The desired positions and alignments of the projections can be determined empirically or through simulation calculations.
The invention will now be described in greater detail with reference to the attached drawing using a non-restrictive exemplary embodiment. In the drawing:
Fig. la shows a schematic cross section of an electrolytic cell for the extraction of aluminium oxide according to the state of the art, Fig. lb shows the electrolytic cell from Fig. 1 a in an external longitudinal view, Fig. lc shows a perspective view partially in section of an electrolytic cell for the extraction of aluminium from aluminium oxide according to the state of the art, Fig. 2 shows a perspective view of a section of an electrolytic cell according to an embodiment of the invention, Fig. 3 shows a perspective view of a section of an electrolytic cell according to an alternative embodiment of the invention, Fig. 4 shows the cross-section of projections according to the invention, Fig. 5 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, ' SGL CARBON SE
14.03.2013 Fig. 6 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, Fig. 7 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, Fig. 8 shows a perspective view of a section of an electrolytic cell according to a further alternative embodiment of the invention, Fig. 9a shows a top view and a sectional view of a screw-in projection, Fig. 9b shows a sectional view of an alternative embodiment of a screw-in projection, Fig. 9c shows a perspective view of a further alternative embodiment of a screw-in projection, Fig. 10a shows a perspective view of a screw for a screw-in projection in accordance with Fig. 9c, and Fig. 10b shows a perspective view of an alternative embodiment of a screw for a screw-in projection according to Fig. 9c.
The same reference symbols are used in the figures to refer to the same or corresponding elements in the different representations.
With reference to Figure 2, an embodiment of an electrolytic cell according to the invention is shown as a perspective view, denoted in its entirety by the reference symbol 100. The cathode 1 and side wall 1a shown here are suitable for use in an electrolytic cell, as depicted in Figures la to 1c, instead of the cathode 1 and the side wall la shown there.
As can be seen, the side wall la in this exemplary embodiment is not formed " SGL CARBON SE 2010/052W0 12 14.03.2013 in one piece, but comprises two side walls la running parallel to one another, which are made up of individual side wall blocks 1a1 . In a similar way, a cathode 1 is made up of several cathode blocks 1b1. The side walls 1a and the cathode 1 together bound a tank 1c. Side walls on the narrow ends of the tank (parallel to the image plane of Figure 2) are not shown in the figure.
This tank construction corresponds to a cathode design customary at present. The embodiment of the electrolytic cell 100 shown here is not obligatory, however.
Likewise, the cathode tank may, for example, be round or square in shape.
What is essential in the context of the invention is that projections ld protrude into the tank lc of the electrolytic cell 100, which may extend from the cathode 1 and/or from the side wall 1a or the side walls 1a. In the embodiment shown, several projections 1d exist, which are attached to the cathode 1 (perpendicular to the image plane of Figure 2) in a longitudinal direction spaced at equal intervals relative to one another. Although only three projections 1d are shown on the left side wall la in the diagram, it should be noted that it is advisable in the interests of symmetry for projections 1d to be formed on both side walls. In the example shown, no projections were shown on the right side, simply in the interests of making the figure clear.
As can be seen, the projections 1d are each positioned in the area of the seams, so-called "ramming seams" le, which are so called because during assembly of the cathode 1 from cathode blocks 1a1 and the side wall 1a from side wall blocks 1a1, these seams are sealed by ramming with a mass, which is similarly referred to as a ramming mass if. The ramming mass if not only acts as a sealing agent in the example shown, but at the same time serves to secure the projections 1d in the area of the side walls la. During production of the cathode 1, the projections 1d may be rammed from the top along with the ramming mass If into the ramming seams le, in such a way that they are held at one end in the respective seam le, as shown, while a second end projects into the inside of the tank 1c. In the example shown, the projections 1d are directed from the side wall la in each case towards the cathode's longitudinal axis L. If, as is traditionally the case, the side wall blocks are not joined by ramming, the projections are fixed in the seams between the side wall blocks 13 14.03.2013 with ramming mass or glue, for example.
As can further be seen, a lower edge 1d1 of the respective projections 1d is not parallel to the cathode 1, but is tilted relative to the same. This means there is a wedge-shaped gap between the cathode 1 and the projection 1d, which means that when liquid aluminium is used, it can also flow under the projection 1d. This may be advantageous from a flow point of view.
Fig. 3 shows a modification of the exemplary embodiment, in which projections 1d protrude into the inside of the tank 1c from the cathode blocks 1b1 rather than from the side wall la. In this variant the projections 1d are disposed offset in pairs relative to one another, which may be advantageous to the selective influencing of flow conditions.
The projections 1d may be moulded bodies preferably made from anthracite, graphite or another carbon material. The material used for the projections 1d advantageously has a lower electrical conductivity than that of the cathode 1 or side walls la. In addition, it is advantageous for the material to exhibit a high resistance to mechanical wear (abrasion), so that the projections 1d preferably exhibit at least the same service life as the cathode 1 itself, so that they do not have to be renewed more frequently than the cathode 1 and/or side walls la of the electrolytic cell. Alternatively, CFC materials or panels and foils made from compressed, expanded graphite, for example, may be used for the projections 1d.
It may be advantageous for the projections to exhibit a layer composition. A
layer composition of this kind may, for example, be accomplished with the aforementioned materials. In particular, a middle layer may contain a CFC
material or be made from this and outer layers may contain compressed expanded graphite. Mechanical stresses and chemical loads can be particularly effectively resisted by material combinations of this kind.
It may furthermore be advantageous for the outer layers not to jut out or to barely jut out beyond the seam, so that the projection jutting into the inside of . SGL CARBON SE
14.03.2013 the tank is formed at least essentially from the middle layer, while the outer layers assume the function of holding the middle layer in the seam. Hence, a CFC layer that juts into the inside of the tank may be held in the seam by compressed, expanded graphite or a carbonaceous ramming mass as outer layers.
The configuration shown here and the form of the projections should only be regarded as a non-restrictive example. This involves a cathode, which can be used in connection with the electrolytic cell shown in Figures la to 1 c, in which the current is conducted in the cathode area through current supply bars 3 parallel to the cathode blocks lbl of the cathode 1. However, embodiments are also conceivable in principle in which the current supply is in a vertical direction perpendicular to an underside of the cathode 1. The most suitable configuration of cathode projections in each specific embodiment of electrolytic cells may simply be determined by considering the main areas of increased wear of the cathode concerned. The person skilled in the art will then easily be able to determine suitable positions and forms for the projections Id, taking account of the fluid dynamics. Examples of advantageous projections are shown in cross-section in Fig. 4.
In accordance with an alternative variant of the exemplary embodiment, rather than being disposed in the seams le, the projections are screwed to the cathode 1 or the side wall blocks lal.
Projections id are used for this, as are depicted, for example, in Figures 9a and 9b. In a first variant, projections id are provided in one piece with a thread unit 9 (Fig. 9a), in which case only a base section 10 extends from the projection id.
In a second variant, which is depicted in Fig. 9b, the thread unit 9 is produced separately from the projection and its upper section 11 is screwed with its thread 12 into a matching mating thread in the projection id. In both variants the screw-in projections id can be screwed into side wall blocks lal, as shown in Fig. 5.
15 14.03.2013 In a further variant of the screw-in projection 1d, which is depicted in Fig.
9c, the at least one projection 1d is provided with two threaded through-holes.
Screws 9 are screwed into the through-holes, which can be screwed by means of a slot 13 and a matching screwing tool (not shown) into the mating thread of the cathode 1, for example. Fig. 9c shows screws 9, which have a cylindrical geometry in their upper section 11, but have a base section 10, which is screwed into the cathode 1, which is conically formed. The screw 9 is also depicted alone in Fig. 10a.
Fig. 10b shows a variant of the screw 9 exhibiting a single, continuous conical thread in the upper section 14 and the base section 15.
Figures 6 to 8 show how, particularly with this kind of double screw connection, a multiplicity of positions and alignments of projections 1d is possible in the electrolytic cell 100.
In Fig. 6 projections 1d of varying size are disposed at right angles to the cathode base, but at irregular intervals from the side wall la.
In Fig. 7 projections 1d are screwed at an slanting setting angle to the side wall blocks 1a1.
In Fig. 8 projections 1d, similar as in Fig. 7, are screwed to the cathode at slanting angles instead of the side wall 1.
The exact positions and angles are optimised depending on the prevailing flow profile within the electrolytic cell by computer simulation. The positions of several projections are not necessarily evenly distributed symmetrically within the electrolytic cell or in the individual cathode blocks in each case.
Individual positions of this kind may be achieved by tapping in the otherwise finished electrolytic cell, for example.
In relation to the cathode materials, any materials known to the person skilled in the art and suitable for the electrolysis of aluminium from aluminium oxide 16 14.03.2013 may be used. Suitable materials are specified in DE 10261745, for example, the content of which, in this respect, is to be incorporated here by reference.
Graphite has proved to be particularly favourable in this respect, due to its temperature resistance and due to its low specific electrical resistance.
With an electrolytic cell according to embodiments of the invention, the power loss of the same during the performance of fused-salt electrolysis to extract aluminium through suppression of the wave formation in the produced aluminium melt can be significantly reduced. Moreover, the mechanical wear of the cathode is also reduced, as the liquid movements of the aluminium are reduced.
' . SGL CARBON SE
14.03.2013 Reference list 1 Cathode 1a Side wall 1a 1 Side wall block 1b1 Cathode block 1c Tank 1d Projection le Ramming seams if Ramming mass 2 Mounting 3 Current supply bars 4 Anode Aluminium 6 Mixture (aluminium oxide, cryolite) 6a Crust of solidified mixture 6 7 Negative pole, voltage source 8 Positive pole, voltage source 9 Thread unit, screw Base sector of the screw 11 Upper section of the screw 12 Thread 13 Slot 100 Electrolytic cell
Claims (18)
1. An electrolytic cell used to extract aluminium from its oxide, exhibiting a cathode (1) and at least one side wall (1a), which together bound a tank (1c), characterised in that at least one projection (1d) is formed within the tank (1c), which extends from the cathode (1) or a side wall (1a) into the tank (1c).
2. The electrolytic cell according to claim 1, characterised in that the at least one projection (1d) extends beyond the cathode (1) and/or the wall (1a) by between approximately 5 cm and 50cm.
3. The electrolytic cell according to claim 1 or 2, characterised in that there are several projections (1d), which are disposed at regular or irregular intervals to one another.
4. The electrolytic cell according to claim 3, characterised in that the tank (1c) has a rectangular form when viewed from above with a side wall (1 a) on every longitudinal side, wherein projections (1d) protrude into the inside of the tank (1c) from both side walls (1 a).
5. The electrolytic cell according to claim 3 or 4, characterised in that the at least one side wall (1 a) comprises side wall blocks (1a1).
6. The electrolytic cell according to one or more of the preceding claims, characterised in that the cathode (1) comprises a multiplicity of cathode blocks (1b1).
7. The electrolytic cell according to claim 5 or 6, characterised in that ramming seams (1e) filled with ramming mass (1f) extend between side wall blocks (1a1) and/or cathode blocks (1b1), wherein the at least one projection (1d) is held at one end in a ramming seam (1e) by the ramming mass.
8. The electrolytic cell according to claim 7, characterised in that a projection (1d) is held in each of the ramming seams (1e) between the side wall blocks (1a1).
9. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) exhibits a rectangular form with rounded edges in cross-section.
10. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) is made from anthracite, carbon or graphite.
11. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) is made from CFC
material and/or at least partly compressed expanded graphite.
material and/or at least partly compressed expanded graphite.
12. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) exhibits a layer composition.
13. The electrolytic cell according to claim 12, characterised in that a middle layer of the layer composition extends beyond the cathode (1) and/or side wall (la) and outer layers (1e) are held in the seam (1e).
14. The electrolytic cell according to claim 12 or 13, characterised in that the middle layer exhibits CFC material and/or the outer layers exhibit at least partially compressed expanded graphite and/or ramming mass.
15. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) exhibits a lower specific electrical conductivity than the cathode (1) and/or the side walls (1a) of the electrolytic cell.
16. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) is provided as a detachable projection (1d).
17. The electrolytic cell according to one or more of the preceding claims, characterised in that the at least one projection (1d) is provided as a screw-in projection (1d).
18. The electrolytic cell according to one or more of the preceding claims, characterised in that the projection (1d) is secured to the cathode (1) and/or a side wall (1a) of the electrolytic cell by means of at least one thread unit (9).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE201010041083 DE102010041083A1 (en) | 2010-09-20 | 2010-09-20 | Electrolysis cell for the production of aluminum |
| DE102010041083.7 | 2010-09-20 | ||
| PCT/EP2011/066321 WO2012038426A1 (en) | 2010-09-20 | 2011-09-20 | Electrolysis cell for extracting aluminium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2811553A1 true CA2811553A1 (en) | 2012-03-29 |
Family
ID=44651849
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2811553A Abandoned CA2811553A1 (en) | 2010-09-20 | 2011-09-20 | Electrolytic cell for extracting aluminium |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP2619351A1 (en) |
| JP (1) | JP2013537939A (en) |
| CN (1) | CN103154325A (en) |
| CA (1) | CA2811553A1 (en) |
| DE (1) | DE102010041083A1 (en) |
| RU (1) | RU2013118273A (en) |
| WO (1) | WO2012038426A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115142093B (en) * | 2022-07-14 | 2024-01-30 | 湖南大学 | Prebaked anode antioxidant, preparation method and application thereof |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4175022A (en) * | 1977-04-25 | 1979-11-20 | Union Carbide Corporation | Electrolytic cell bottom barrier formed from expanded graphite |
| CH643600A5 (en) * | 1979-12-05 | 1984-06-15 | Alusuisse | ELECTROLYSIS CELL FOR PRODUCING ALUMINUM. |
| JPS5741393A (en) * | 1980-08-27 | 1982-03-08 | Sumitomo Alum Smelt Co Ltd | Electrolytic furnace for production of aluminum |
| EP0103350B1 (en) * | 1982-06-18 | 1986-04-16 | Alcan International Limited | Aluminium electrolytic reduction cells |
| EP0172170A1 (en) * | 1984-02-03 | 1986-02-26 | Commonwealth Aluminum Corporation | Refractory hard metal containing plates for aluminum cell cathodes |
| EP0544737B1 (en) * | 1990-08-20 | 1996-06-05 | Comalco Aluminium, Ltd. | Ledge-free aluminium smelting cell |
| AU688098B2 (en) * | 1994-09-08 | 1998-03-05 | Moltech Invent S.A. | Aluminium electrowinning cell with improved carbon cathode blocks |
| CN1195900C (en) * | 1998-11-17 | 2005-04-06 | 艾尔坎国际有限公司 | Wettable and erosion/oxidation-resistant carbon-composite materials |
| DE10261745B3 (en) | 2002-12-30 | 2004-07-22 | Sgl Carbon Ag | Cathode system for electrolytic aluminum extraction |
| PL1845174T3 (en) | 2006-04-13 | 2011-10-31 | Sgl Carbon Se | Cathodes for aluminium electrolysis cell with non-planar slot design |
| CN100478500C (en) * | 2007-03-02 | 2009-04-15 | 冯乃祥 | Abnormal cathode carbon block structure aluminum electrolysis bath |
| CN201049966Y (en) * | 2007-05-23 | 2008-04-23 | 冯乃祥 | Abnormal structure cathode carbon block of aluminum electrolysis bath |
| CN201261809Y (en) * | 2008-08-12 | 2009-06-24 | 高德金 | Cathode inner lining with molten aluminum magnetic vortex stream adjustment device |
| CN101709483B (en) * | 2009-11-02 | 2011-10-05 | 广西来宾银海铝业有限责任公司 | Baking start-up method for large scale special-shaped cathode aluminium electrolytic cell |
| CN101724859B (en) * | 2009-12-15 | 2011-05-18 | 中南大学 | Method for roasting aluminum electrolytic bath with polymorphic structure cathode |
-
2010
- 2010-09-20 DE DE201010041083 patent/DE102010041083A1/en not_active Withdrawn
-
2011
- 2011-09-20 CA CA2811553A patent/CA2811553A1/en not_active Abandoned
- 2011-09-20 EP EP11757662.9A patent/EP2619351A1/en not_active Withdrawn
- 2011-09-20 JP JP2013529633A patent/JP2013537939A/en not_active Ceased
- 2011-09-20 CN CN2011800452592A patent/CN103154325A/en active Pending
- 2011-09-20 WO PCT/EP2011/066321 patent/WO2012038426A1/en active Application Filing
- 2011-09-20 RU RU2013118273/02A patent/RU2013118273A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| CN103154325A (en) | 2013-06-12 |
| EP2619351A1 (en) | 2013-07-31 |
| DE102010041083A1 (en) | 2012-03-22 |
| JP2013537939A (en) | 2013-10-07 |
| RU2013118273A (en) | 2014-10-27 |
| WO2012038426A1 (en) | 2012-03-29 |
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| EEER | Examination request |
Effective date: 20130318 |
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| FZDE | Discontinued |
Effective date: 20160526 |