Support assembly for anodes of electrolytic cells for the production of primary aluminium

Abstract

A support assembly (12) for supporting prebaked anodes (14) for a Hall-Heroult cell (10) for the production of primary aluminum, comprising a plurality of connecting plates (24), wherein each connecting plate (24) is arranged at a lower end of a respective stub (22) and has a diameter (D4) that is greater than a diameter (D3) of the stub (22).

Description

Technical Field

[0001] This invention belongs to the field of components for producing primary aluminum using Hall-Hêroult cells; in particular, this invention relates to an original support assembly for the anode of a Hall-Hêroult cell that allows for extended anode operating cycle life and reduced weight of the final anode waste. Background Technology

[0002] Primary aluminum is produced in Hall-Hêroult electrolytic cells. The alumina dispensed into the electrolytic cell is dissolved in an electrolytic bath of cryolite and aluminum fluoride (AlF3) at a temperature of approximately 950°C, and is reduced to aluminum during electrolysis by transferring direct current from the anode to the carbon cathode.

[0003] A typical prebaked anode support assembly includes a hook formed by an anode beam, a transition joint, a yoke, and multiple short columns.

[0004] To connect to the support assembly, the anode has multiple transverse slots at its top, one for each short post. A predetermined amount of molten cast iron is poured into the remaining space between the short post and the corresponding slot. Once the cast iron solidifies, the short post remains embedded in the anode's slot, and the solidified cast iron ring forms the mechanical and electrical connection between the anode beam and the anode.

[0005] Electrolytic cells are typically equipped with several support components, each supporting its own anode. The current flowing through each anode is basically equal to the total circuit current divided by the number of support components in the electrolytic cell.

[0006] The normal operating cycle of prebaked anodes under existing technology is generally between 25 and 30 days, ending when the anode has reached its minimum height. Below this minimum height, there is a risk of cast iron ring contamination of the molten bath. In this case, a new support assembly for the new anode is needed to replace the support assembly supporting the worn anode.

[0007] The carbon in the discarded anode, which constitutes the butt end of the anode, typically accounts for 20-30% of the weight of the new anode and is recovered in pipelines used to recycle the carbon in the butt end of the anode.

[0008] To prevent the cast iron ring from contaminating the molten bath and aluminum, a layer of carbon is left approximately 50 mm below the ring, which is part of the anode scrap thickness. Considering the hole depth, the total thickness of the anode scrap is between 150 and 200 mm.

[0009] The duration of the anode's lifespan depends directly on the total thickness of the waste, which in turn depends directly on the depth of the short posthole at the top of the anode. According to existing solutions, the average depth H1 of the posthole is approximately 120 mm. Considering a safety thickness of approximately 50 mm, the total thickness of the Hbutt waste is approximately 170 mm, which is approximately 26% of the new anode's height of 650 mm.

[0010] Furthermore, in existing solutions, the current density distribution is non-uniform because the current converges towards the short post, but only through a limited area of ​​the cast iron ring (particularly those areas of the ring with higher carbon contact pressure). The contact resistance between the short post and the anode is non-uniform, and the voltage drop between the short post and the anode is typically in the range of approximately 80 mV to 130 mV. Due to the high-density localized current, the Joule effect inside the anode generates heat and leads to energy loss in the battery.

[0011] Several patent documents have proposed methods to improve the energy efficiency of anodes, eliminate the use of cast iron, and improve the use of carbon. For example:

[0012] Norsk Hydro's international application WO-A1-2016 / 130014 proposes replacing cast iron with mechanical support elements, which require anodizing and a metal particle intermediate layer for electrical connection between the carbon and the hook. However, the mechanical particles must be recycled, the support assembly differs from those commonly used in industry, and it makes retrofitting existing support assemblies impossible.

[0013] Laval University's international application WO-A1-2012 / 100340 proposes a seamless connector (part). It provides longitudinal grooves instead of holes for short columns, and the steel component joined to the cast iron is a bar with a rectangular cross-section;

[0014] - Norsk Hydro's paper US 7,901,560 proposes creating a slit at the bottom of the anode to reduce energy consumption;

[0015] Storvik's international application WO-A1-2016 / 108696 and Servico's international application WO-A1-2002 / 42525 propose a yoke with copper components housed within a steel component, and without short posts welded to the steel arms of the steel yoke.

[0016] Finally, further exemplary embodiments are shown in CA2838113A1 and GB2569382A; however, these embodiments only show cast iron rings surrounding short posts. Summary of the Invention

[0017] The purpose of this invention is to meet industrial needs while overcoming the shortcomings mentioned in the prior art, mainly to increase the service life of the anode and reduce the weight of the discarded anode butt end.

[0018] This objective is achieved through the support components described in the embodiments of this application. Other advantageous embodiments of the invention are also described herein. Attached Figure Description

[0019] The features and advantages of the support components of the present invention will become apparent from the following description, given by way of non-limiting example with reference to the accompanying drawings, wherein:

[0020] - Figure 1 The Hall-Hêroult cell for producing primary aluminum and a pair of support assemblies for the corresponding anodes are schematically depicted.

[0021] - Figures 2 to 6 relate to the prior art, in particular:

[0022] a) Figure 2 shows the support assembly assembled and connected to the anode;

[0023] b) Figure 3 shows the support assembly of Figure 2 as a separate component;

[0024] c) Figures 4a and 4b show examples of the cast iron ring of the cured support assembly;

[0025] d) Figure 5 shows the support assembly for anode wear;

[0026] e) Figure 6 shows the slot and the associated short post.

[0027] - Figures 7 to 17 In particular, regarding the support components according to the invention:

[0028] a) Figure 7 The support assembly assembled and connected to the anode is shown;

[0029] b) Figure 8 Depicting Figure 7 The arm of the support component is assembled and connected to the associated anode;

[0030] c) Figure 9 An arm with corresponding slots is depicted in the assembly of the support components;

[0031] d) Figure 10a and Figure 10b The ring of the support assembly after curing is shown;

[0032] e) Figure 11a , Figure 11b and Figure 11cA further embodiment of the arm of the support assembly is shown;

[0033] f) Figures 12 to 17 Other shapes of the arms supporting the component are shown. Detailed Implementation

[0034] Figure 1 The Hall-Hêroult tank 10 for producing primary aluminum and a pair of support assemblies 12 in their working positions are schematically depicted, the support assemblies 12 being immersed in the tank. Each support assembly 12 includes an anode beam 16, typically made of aluminum, connected to an anode 14, typically prebaked, made of carbon.

[0035] Specifically, for the connection between the anode beam 16 and the anode 14, the support assembly 12 includes a transition joint 18 welded to the lower end of the anode beam 16 and a yoke 20 welded to the transition joint 18. The yoke 20 is typically made of steel and is usually bimetallic (steel-aluminum). Furthermore, the yoke 20 includes multiple independent arms 20a, and the support assembly includes multiple short posts 22, typically made of steel, each short post 22 welded to a corresponding arm 20a of the yoke 20.

[0036] The short column 22, which is usually cylindrical, has a characteristic width, which is the dimension that represents the maximum overall size of the short column, such as the maximum outer diameter D3.

[0037] according to Figure 7 , Figure 8 and Figure 9 The support assembly 12 also includes a plurality of connecting plates 24, each typically cylindrical and preferably made of steel, connected to the lower end of a corresponding short post 22. According to the invention, the connecting plate 24 is defined at the top by an upper surface 24a and at the bottom by a lower surface 24b, having a maximum outer diameter D4, wherein the diameter D4 of the connecting plate 24 is greater than the diameter D3 of the short post (D4>D3).

[0038] For example, the connecting plate 24 is welded to the short column 22; in a variant embodiment, the short column and the connecting plate form a single body.

[0039] Finally, the support assembly 12 includes a plurality of rings 26, typically made of cast iron and solidified iron, for connecting the support assembly 12 to the anode; according to a further embodiment, the rings are made of carbon paste or composed of carbon-based adhesive. Each cast iron ring 26 connects the connecting plate 24 of the corresponding short post 22 to the anode 14 by engaging with a corresponding transverse slot 14a of the anode 14.

[0040] To achieve the connection between the connecting plate 24 and the anode 14, a plurality of slots 14a are provided on the upper part of the anode 14; each slot 14a has a plurality of grooves 14b on its side surface, wherein each groove 14b extends axially in general and is inclined.

[0041] The connecting plate 24 is positioned in the corresponding slot 14a, and a predetermined amount of cast iron is poured into the slot. The solidified cast iron forms a ring 26. The ring 26 is firmly attached to the plate 24 by means of the thermal shrinkage of the cast iron after solidification, and is firmly attached to the anode 14 by means of the groove 14b; in particular, the cast iron that has solidified in the groove 14b forms a plurality of flaps 26b of the ring 26.

[0042] exist Figure 8 In the design, the slot 14a has a diameter D2 (excluding the groove), a characteristic depth H2, and a side surface extension S2. Hsafety is the safe thickness of the consumed anode, Hbutt is the thickness of the anode waste, and H3 is the protrusion height of the connecting plate 24 from the upper surface of the anode 14.

[0043] Compared to the prior art shown in Figure 6, it is clear that, due to the use of the connecting plate 24, the diameter D2 of the slot 14a is larger than the diameter D1 of the slot in the prior art solution; the depth H2 of the slot 14a is smaller than the depth H1 of the slot in the prior art solution. Specifically, H4 = H1 - H2 is the height reduction between the solution of the present invention and the solution of the prior art, and corresponds to the height reduction of the anode rough end scrap.

[0044] Figure 10a and Figure 10b An embodiment of the ring 26 is shown, comprising a tubular body 26a of thickness “t” and a plurality of fins 26b projecting radially outward from the body 26a, the fins 26b having significant axial and inclined extensions relative to the central axis of the body.

[0045] Figure 11a An embodiment of the invention is depicted, wherein the connecting plate 24 is a steel disc welded to the lower end of the short column 22, and the height of the connecting plate partially overlaps with the height of the short column.

[0046] Figure 11b Another embodiment of the invention is depicted, wherein the connecting plate 24 is a steel disc welded to the lower end of the short column 22, and the height of the connecting plate completely overlaps with the height of the short column.

[0047] Figure 11c Another embodiment of the invention is depicted, wherein the connecting plate 24 is a steel disc welded to the lower end of the short column 22, located entirely below the short column.

[0048] Furthermore, according to one embodiment of the present invention, the number of grooves 14b in the slot 14a is between 11 and 30, that is, more than the number provided in the prior art solution.

[0049] exist Figure 11a , Figure 11b and Figure 11c In the illustrated embodiment, the position of the ring relative to the short post can be changed, thereby altering the contact area accordingly. Therefore, the flow of heat from the anode to the arm of the corresponding short post can be controlled.

[0050] In the solution according to the invention, the heat generated by the current inside the anode through the Joule effect is less than that in known solutions because the larger surface area of ​​the slot S2 reduces the current density and contact resistance in the interface region between the connecting plate (steel), the ring (cast iron), and the anode (carbon).

[0051] The contact resistance also depends on the pressure between the side surface 14a of the slot 14 and the carbon anode, as well as the profile of the side surface 14a, which can be, for example, flat or knurled.

[0052] Figure 12 Another embodiment of the invention is depicted, wherein the slot 14a has a tapered side surface with an extension S2, which is preferably obtained by tool machining, and the connecting plate 24 has a tapered side surface with an extension S2.

[0053] Figure 13 Another embodiment of the invention is shown, wherein the side surface of the connecting plate 24 is knurled to increase the electrical contact area and mechanical support of the anode. Furthermore, preferably, the slot 14a has a tapered side surface, and the connecting plate 24 also has a tapered side surface.

[0054] Figure 14 In another embodiment of the invention, the support assembly 12 cooperates with the cover 28, which is arranged to cover the transition area between the short post 22 and the connecting plate 24, and is adapted to cover the end of the short post 22 and the upper part of the connecting plate 24. Preferably, the cover 28 rests on the upper surface 14c of the anode 14 and rests on the connecting plate 24 according to its internal shape.

[0055] Preferably, the cover 28 has a total height H5 such that when the anode 14 is fully immersed in the electrolytic bath, the short column is protected and will not be lapped by the liquid electrolytic bath.

[0056] For example, the cover 28 has an integral flanged annular shape and includes two connectable half-shells 28a, 28b, which are held together, for example, by carbon glue, metal wire or carbon fiber.

[0057] Figure 15 Another embodiment of the invention is shown, wherein the cover 28 consists of a tube segment partially resting on the upper surface 14c of the anode 14, with an opening at the top and having a height H5.

[0058] The tube thus defines an internal space 30, which is preferably filled with a plurality of protective fragments 32, such as unbaked carbon paste, to prevent the liquid bath from entering and to better thermally insulate the upper part of the anode.

[0059] Figure 16 Another embodiment of the invention is depicted, wherein the cover 28 has an integrally flanged annular shape and is composed of a lower part 28a and an upper part 28b. The lower part 28a is composed of two half-shells 281, which are connected and rest on the upper surface 14c of the anode 14 and the connecting plate 24; the upper part 28b is composed of two half-shells 283, 284, which are connected and rest on the upper part 28a.

[0060] Preferably, the half-shells 281, 282, 283, and 284 are connected together using carbon glue or steel tips or needles protruding from the connecting plate 24.

[0061] In the last 3 or 4 days of the anode's life cycle, in order to maintain the same distance between the anode and cathode, the anode must be moved deeper into the liquid bath, which may involve submerging the upper part of the short column by an additional segment H4 = H1 - H2. The liquid bath will corrode and dissolve the steel unless a cap 28 made of, for example, carbon paste is used to protect the vertical part of the short column and the upper part of the plate.

[0062] The cap can be made as a single piece, in two halves, or in four or more parts, and is made from a non-pre-baked carbon paste, slurry, or carbon glue mixed with a binder. For example, aggregates of calcined coke particles and pitch particles can be used, along with inorganic polymer binders processed from plant products such as lignite, molasses, or other organic derivatives, or phenolic or epoxy resins can be used to bond them together. This binder is intended to function at temperatures from room temperature to approximately 450°C, from which the pitch begins to carbonize, and to act as a binder at temperatures of approximately 1000°C and above.

[0063] Preferably, a non-prebaked carbon paste, the same paste used for producing the anode, is used. In this case, the cover is achieved by arranging a pre-formed shell around the short column and above the plate, the shell being made as a single piece or in several parts.

[0064] Figure 17Another embodiment of the present invention is shown, in which the connecting plate 24 is partially hollow or empty; for example, the connecting plate has a cavity 34 that opens to the lower surface 24b facing the electrolytic bath. Advantageously, this feature makes it possible to reduce the weight of the connecting plate and control the heat flow.

[0065] According to this embodiment, preferably, the support assembly 12 cooperates with a cover composed of a pipe section 36, and the pipe section 36 is partially placed on the upper surface 14c of the anode 14 with an open top. The pipe 36 defines an internal space 30, and the internal space 30 is preferably filled with debris 32.

[0066] In addition, preferably, the connecting plate 24 has one or more channels 38 connecting the upper surface 24a and the cavity 34, which are adapted to allow a part of the debris 32 to enter the cavity 34 from the internal space 30. Advantageously, this allows the cavity 34 to be filled with debris 32 and restricts the molten bath from entering the cavity 34.

[0067] According to the present invention, the ratio between the diameter D4 of the connecting plate and the diameter D3 of the short column is between 1 and 3.5 (1 < D4 / D3 ≤ 3.5), preferably between 1.5 and 3 (1.5 ≤ D4 / D3 ≤ 3).

[0068] According to one aspect of the present invention, the ratio D4 / H2 between the diameter D4 of the connecting plate and the depth H2 of the connecting plate is between 1.92 and 10 (1.92 ≤ D4 / H2 ≤ 10). For example, the ratio D4 / H2 = 220 mm / 115 mm = 1.92 or D4 / H2 = 400 mm / 40 mm = 10.

[0069] However, according to the prior art solution, the ratio D3 / H1 between the diameter D3 of the short column and the depth H1 of the short column is between 1.12 (180 mm / 160 mm) and 1.83 (220 mm / 120 mm).

[0070] Advantageously, in order to ensure the same or better mechanical holding force between the support assembly and the anode, according to the prior art, the lateral contact area π*D4*H2 of the plate is equal to or greater than the lateral area π*D3*H1 of the short column.

[0071] According to another aspect of the present invention, the ratio D2 / H2 between the slot hole diameter D2 and the slot hole depth H2 is between 2.2 and 11. For example, the ratio D2 / H2 = 390 mm / 80 mm = 4.875.

[0072] According to another variant embodiment of the present invention, the slot hole has a square or rectangular cross-section or any other polygon. However, such a cross-sectional shape can only be obtained by processing the pre-baked anode. Therefore, from the perspective of production economy, the circular cross-section is the preferred embodiment.

[0073] Creatively, according to the present invention, the carbon utilization efficiency of the anode and the duration of the anode are increased.

[0074] Specifically, the depth H2 of the slot according to the invention is less than the depth H1 of the hole according to the prior art, and the diameter D2 of the slot according to the invention is greater than the diameter D1 of the hole according to the prior art, resulting in a lower thickness of the anode rough end scrap. This corresponds to a greater useful height of the anode, i.e., "anode height gain" H4 = H1-H2, thus increasing the anode's operating cycle time.

[0075] Furthermore, the contact area A2+S2 between the slot and carbon according to the invention is greater than the contact area A1+S1 of the hole according to the prior art. Therefore, the volume V2 of the slot according to the invention is equal to A2*H2, and greater than the volume V1 = A1*H1 of the hole according to the prior art. Advantageously, the carbon cost of the anode of the invention is lower than that of the prior art because the weight is reduced by a factor (V2-V1)*1.6 (where 1.6 is the apparent density of carbon).

[0076] Furthermore, the slots according to the invention are obtained through the same process as in the prior art, i.e., by vibratory pressing of carbon paste. Therefore, it is advantageous that, after modifying the cover of the vibratory pressing station to accommodate the larger diameter and smaller depth of the mandrel used to create the holes, the same production line as in the prior art can be used.

[0077] Advantageously, according to the present invention, the mechanical support of the anode is improved or remains unchanged compared to prior art solutions. In particular, this advantage is achieved through a connecting plate and associated slots having a side surface area S2 that is greater than or at least equal to the area of ​​the average side surface S1 of the prior art.

[0078] Furthermore, according to the present invention, in order to compensate for the decrease in hole depth from H1 to H2, the number of grooves in the slot is greater than the number of grooves in the prior art solution. In fact, the total length of the grooves according to the present invention is greater than or equal to the total length of the grooves relative to the prior art. Specifically, the prior art solution provides 6 to 10 grooves, preferably 8; according to the present invention, 11 to 30 grooves are conceivable.

[0079] Furthermore, it is advantageous that existing anodes and anode assemblies can be refurbished and improved according to the present invention. It is sufficient to weld a connecting plate at the location of the short post and modify the corresponding slots.

[0080] In addition, from a logistical and economic perspective, another vibratory pressing unit produces caps within the green anode production line or anode assembly line. For example, a mixture or granules of preheated carbon paste are filled into a mold, and the press acts to form and compact the cap, allowing it to be processed without baking.

[0081] Example Examples

[0082] Exemplary embodiments of the support components according to the present invention are defined in Table 1.

[0083]

[0084] In Table 1, the dimensions are defined as follows:

[0085] - Based on the anode dimensions of existing technology:

[0086] a) Anode dimensions: W 655 mm × H 650 mm × W 1,605 mm;

[0087] b) Hole diameter: D1 = 15 + 220 + 15 = 250 mm;

[0088] c) Hole depth: H1 = 120 mm;

[0089] d) Base area of ​​the hole: A1 = 49,087 mm 2 ;

[0090] e) Volume of the hole: V1 = 5.890 dm 3 .

[0091] - The dimensions of the anode according to the present invention:

[0092] a) Anode dimensions: W 655 mm × H 650 mm × W 1,605 mm;

[0093] b) Hole diameter: D2 = 15 + 360 + 15 = 390 mm;

[0094] c) Hole depth: H2 = 80 mm;

[0095] d) Base area of ​​the hole: A2 = 119,459 mm 2 ;

[0096] e) Pore volume: V2 = 9.557 dm 3 .

[0097] In this example, the thickness of the anode waste was reduced by 40 mm compared to existing solutions; this increased the anode's operating cycle duration from two days to four days, corresponding to an increase in operating cycle time from 6% to 15%. The carbon weight utilization rate of the anode was improved by approximately 10%.

[0098] The initial weight of the anode according to the invention is about 3% lower than that of the prior art solution, which is due to the lower weight given by the difference (V2 - V1) between the volume of the slot according to the invention and the volume of the slot in the prior art.

[0099] According to the present invention, due to the combination of reduced anode waste thickness and reduced anode weight, the cost of waste recycling is reduced by approximately 35% compared to existing solutions.

[0100] The volume V2 of the connecting plate allows for a reduction in the anode weight per hole by: (9.557 - 5.890) dm 3 * 1.6 kg / dm 3 =5.867 kg. 5.867 kg * 4 (4 holes) = 23.46 kg, or about 3% lighter than the anodes of the prior art.

[0101] The yield based on the anode weight according to the invention is 6% to 15% higher than that of the same size anode in the prior art. This corresponds to an increase in the anode life cycle from an average of two days to three days, which is equivalent to an increase in cycle time from 6% to 10% compared to the cycle time of anodes in the prior art. This corresponds to an average reduction of 35% in waste recycling costs.

[0102] The additional positive effects of the anode according to the invention, resulting from the size of the hole and the short post, are a larger contact area, better current distribution, and a reduction in voltage drop across the anode by about 50 mV to 80 mV.

Claims

1. A support assembly (12) for supporting a pre-baked anode (14) of a Hall-Héroult cell (10) for the production of primary aluminium, comprising an anode beam (16), a yoke (20) made of steel supported by the anode beam (16), and a plurality of short posts (22), the yoke (20) having a plurality of individual arms (20a), wherein each short post (22) welded to the lower end of a respective arm (20a) of the yoke (20) has a diameter D3, the support assembly (12) being characterized in that it further comprises a plurality of connecting plates (24) made of steel, wherein each connecting plate (24) is arranged at the lower end of a respective short post (22) and has a diameter D4, and wherein the ratio between the diameter D4 of the connecting plate and the diameter D3 of the short post satisfies 1 < D4 / D3 ≤ 3.5; wherein, A plurality of slots 14(a) are provided on the upper part of the anode (14).

2. The support component (12) according to claim 1, wherein, The connecting plate (24) is welded to the short column (22).

3. The support component (12) according to claim 1, wherein, The connecting plate (24) and the corresponding short column (22) form a single body.

4. The support component (12) according to any one of claims 1-3, wherein, The connecting plate (24) has a cylindrical outer surface.

5. The support component (12) according to any one of claims 1-3, wherein, The connecting plate (24) has a truncated conical outer surface.

6. The support component (12) according to any one of claims 1-3, wherein, The connecting plate (24) has a knurled outer surface.

7. The support assembly (12) according to any one of claims 1-3 comprises a plurality of cast iron rings (26), each ring (26) being formed in a corresponding slot (14a), wherein each ring (26) comprises a tubular body (26a) internally fastened to the connecting plate (24) and a plurality of blades (26b) radially projecting outward from the body (26a), the plurality of blades (26b) having axial and inclined extensions for connection with the anode (14).

8. The support component (12) according to claim 7, wherein, The number of the fins (26b) is 11 to 30.

9. The support component (12) according to any one of claims 1-3 and 8, wherein, The connecting plate (24) is a disc welded to the lower end of the short column (22), and the height of the connecting plate partially overlaps with the height of the short column.

10. The support component (12) according to any one of claims 1-3 and 8, wherein, The connecting plate (24) is a disc welded to the lower end of the short column (22), and the height of the connecting plate completely overlaps with the height of the short column.

11. The support component (12) according to any one of claims 1-3 and 8, wherein, The connecting plate (24) is a disc welded to the lower end of the short column (22) and is located completely below the short column.

12. The support assembly (12) according to any one of claims 1-3 and 8 includes a transition joint (18), one side of which is welded to the lower end of the anode beam (16) and the other side is welded to the yoke (20).

13. The support component (12) according to claim 1, wherein, The ratio between the diameter D4 of the connecting plate and the diameter D3 of the short column satisfies 1.5 ≤ D4 / D3 ≤ 3.

14. An anode assembly, comprising: - Support component (12) according to any one of claims 1 to 13; as well as - Anode (14) fastened to the support assembly (12).

15. The anode assembly according to claim 14, wherein, The ratio D4 / H2 between the diameter D4 of the connecting plate (24) and the depth H2 of the corresponding slot (14a) satisfies 1.92≤D4 / H2≤10.

16. A cover assembly, comprising: - Support component (12) according to any one of claims 1 to 13; as well as - A cover (28) is applied to the support assembly (12) to cover the transition area between the short column (22) and the connecting plate (24).

17. An anode and cap assembly, comprising: - Support component (12) according to any one of claims 1 to 13; - The anode (14) is fastened to the support assembly (12); and - A cover (28) is applied to the support assembly (12) to cover the transition area between the short column (22) and the connecting plate (24).

18. An electrolytic cell (10) for producing primary aluminum, comprising the anode assembly according to claim 14 or 15.

19. An electrolytic cell (10) for producing primary aluminum, comprising the anode and cap assembly as claimed in claim 17.

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