EP3099844B1 - Electrolysis tank comprising an anode assembly contained in a containment enclosure - Google Patents

Description

The present invention relates to an electrolytic cell, intended for the production of aluminum by electrolysis.

It is known to produce aluminum industrially from alumina by electrolysis according to the Hall-Héroult process. To this end, provision is made for an electrolysis cell conventionally comprising a steel box inside which is arranged a coating of refractory materials, a cathode of carbonaceous material, crossed by cathode conductors intended to collect the electrolysis current at the cathode to lead it to cathodic outlets passing through the bottom or the sides of the box, routing conductors extending substantially horizontally to the next tank from the cathodic outlets, an electrolytic bath in which is dissolved the alumina, at least one anode assembly comprising a substantially vertical anode rod and at least one anode block suspended from the anode rod and immersed in this electrolytic bath, an anode frame from which the anode assembly is suspended via the anode rod substantially vertical and movable with the anode frame relative to the casing and the cathode, and flexible current-raising conductors cell, extending from bottom to top, connected to the conveying conductors of the previous electrolytic cell to carry the electrolytic current from the cathode leads to the anode frame and the anode assembly and the anode of the next tank. The anodes are more particularly of the prebaked anode type with prebaked carbonaceous anode blocks, that is to say baked before introduction into the electrolytic cell.

During the electrolysis reaction, gases are produced, in particular carbon dioxide which is released at the anode and hydrogen fluoride (HF) which escapes from the electrolytic bath. To contain the gases thus produced, a cowling traditionally covers the opening delimited by the box. These gases can then be regularly collected, for example with a view to their treatment and subsequent recovery.

However, the anode rods go through the cowling. Dynamic sealing means are generally provided to prevent gases from leaking through the junction provided between the cowling and the anode rods. By dynamic sealing means is meant sealing means which ensure the confinement of the gases during the movement of the anode rods. Such a dynamic sealing means is known in particular from the document WO2004/035872 on behalf of Aluminum Pechiney. However, during a changing the anode, handling the anode rods, which are part of the anode assembly, can cause damage to the dynamic sealing means with which they cooperate. However, damaged sealing means can affect the sealing of the cowling, so that the gases generated during the electrolysis reaction cannot be collected in full, or that the gas suction rate must be oversized.

Moreover, it is known from the document US3575827 on behalf of Johnson to arrange electrolytic cells transversely with respect to the length of the line which they form, these electrolytic cells comprising an anode assembly with a horizontal plate from which an anode is suspended. This configuration advantageously makes it possible to extract the anodes consumed from the top of the tank. In addition, this document provides for the use of flexible and electrically insulating steel sheets to prevent the escape of gases generated during the electrolysis reaction. These sheets are inserted between the edges of a box and the horizontal plate supporting the anode.

However, the flexible sheets collapse when the horizontal plate supporting the anode is translated downwards in order to move the anode in the electrolytic bath as it is consumed. This crushing generates stresses on the flexible sheets forming the seal, these stresses being capable of ultimately affecting the seal. Moreover, this tightness is all the more difficult to achieve since, for a high productivity and therefore very long tank comprising a plurality of anode assemblies, the difference in altitude between two anode assemblies inherent to the process using prebaked anodes makes this sealing by flexible sheet difficult to implement. In addition, the manipulation of the anode assemblies at the time of the anode changes can cause damage to the flexible sheets providing the seal.

It will therefore be noted that the electrolytic cells of the state of the art comprise anode assemblies which interact with the cowling, in particular at the time of an anode change, so that the tightness of the cowling to the gases generated during of the electrolysis reaction may be affected.

Also, the present invention aims to overcome all or part of these drawbacks by proposing an electrolysis cell offering improved sealing against the gases generated during the electrolysis reaction.

To this end, the present invention relates to an electrolytic cell as defined by claim 1.

Thus, the maintenance of the integrity of the elements forming the containment enclosure and therefore the containment of the gases generated during the electrolysis reaction are independent of any manipulation or movement of the anode assembly, so that the electrolysis according to the invention provides improved sealing.

The anode assembly is at a distance from the containment enclosure and does not interact with the latter, which differs from the electrolytic cells of the state of the art.

Thus, the movable electrical conductor does not extend above the anode blocks, in a volume obtained by vertical translation of a projected surface of the anode blocks in a horizontal plane.

Thus, the electrical connection between the movable electrical conductor and the anode support is necessarily made on one side of the electrolytic cell, but not above the anode blocks, nor advantageously above the opening delimited by the box and the interior lining. The movable electrical conductor therefore does not interfere with vertical extraction of the anode blocks.

The electrolytic cell is intended to be arranged transversely with respect to the length of a row of electrolytic cells to which it belongs.

According to one embodiment, the containment enclosure comprises an upper portion forming a lid, said upper portion being removable to allow extraction of the anode assembly. Such a removable upper portion makes it possible to carry out maintenance operations on the vessel in operation, in particular a change of anode assembly, without having to shut down the vessel or dismantle equipment necessary for the operation of the vessel such as gas suction devices or raw material feeders. The electrolytic cell according to the invention offers the possibility of changing the anodes from the top of the cell, without any equipment of the cell obstructing the vertical stroke of the anode change, which makes it possible to carry out significant structural gains.

According to one embodiment, the electrical conductor is movable and the confinement enclosure comprises a fixed portion which has a window across which the movable electrical conductor extends, the movable electrical conductor comprising a first portion extending exterior of the confinement enclosure and a second portion extending inside the confinement enclosure and to which the anode support is electrically connected.

In other words, the mobile electrical conductor which is mobile, in particular in vertical translation, passes through the fixed portion of the containment enclosure.

Thus, during an anode change, there is no need to manipulate the mobile electrical conductor since the latter passes through the fixed portion of the containment enclosure and not the removable upper portion which is manipulated. to change an anode. This results in simplified and reliable sealing at the level of the window through which the mobile electrical conductor passes.

Advantageously, the electrolysis tank comprises sealing means to prevent gases generated during the electrolysis reaction from leaving the containment enclosure via the window through which the mobile electrical conductor passes.

Thus, the seal is improved.

According to one embodiment, the movable electrical conductor crosses the fixed portion of the confinement enclosure in a substantially vertical manner, and the sealing means comprise a dynamic seal surrounding the movable electrical conductor.

Thus, the seal advantageously remains immobile, on the fixed portion of the containment enclosure, while the mobile electrical conductor translates vertically inside this seal, preferably annular. This solution has the advantage of being economical. Such a seal is not exposed to shocks due to changes of anodes, which differs from the electrolytic cells of the state of the art.

The part of the fixed portion of the containment enclosure traversed vertically by the mobile electrical conductor is a horizontal part which extends substantially horizontally. The first portion of the movable electrical conductor extending outside the containment enclosure is arranged below the part of the fixed portion of the containment enclosure crossed vertically by the movable electrical conductor, while the second portion of the movable electrical conductor extending inside the containment enclosure is arranged above. In other words, the mobile electrical conductor passes through the fixed portion from the bottom upwards from its first exterior portion to its second portion inside the containment enclosure. The length of the electrical electrolysis circuit is then minimized.

The movable electrical conductor advantageously comprises, between the second portion and the first portion, a sealing portion intended to cooperate with the sealing joint which is rectilinear and of constant section. The tightness and the ease of design of the dynamic seal are then improved when such a sealing portion slides through the dynamic seal surrounding it.

According to one embodiment, the movable electrical conductor crosses the fixed portion of the containment enclosure in a substantially horizontal manner, and the sealing means include a sealing member configured to completely close the window of the fixed portion, regardless of the position of the mobile electrical conductor through the window.

Thus, sealing is ensured despite the movement, preferably in vertical translation, of the movable electrical conductor.

Advantageously, the sealing member surrounds the movable electrical conductor and is mounted integral with the movable electrical conductor.

Thus, the sealing member is movable concomitantly with the movable electrical conductor. This solution makes it possible to obtain a more efficient seal than with a sealing member which would be fixed and should adapt to the movement of the mobile electrical conductor.

According to one embodiment, the sealing member corresponds to a metal plate extending in a plane substantially parallel to the fixed portion traversed.

The use of a metal plate has the advantage of a contained cost while making it possible to withstand, without loss of performance in terms of sealing, the high temperatures generated by the electrolytic cell in operation, which can reach several hundred degrees Celsius inside the electrolytic cell.

Advantageously, a compensation member is arranged between the sealing member and the movable electrical conductor.

This compensation member allows the expansion of the movable electrical conductor and/or of the plate, taking into account the heat generated by the electrolytic cell in operation, while filling any play between the movable electrical conductor and the metal plate, which contributes to containment sealing.

According to one embodiment, the electrolytic cell comprises means for guiding the sealing member in translation, the guiding means comprising two substantially rectangular frames fixed against the fixed portion of the containment enclosure so as to surround the window of the fixed portion and arranged relative to each other to delimit between them a space inside which the sealing member is intended to slide, the electrolytic cell further comprising means for expansion compensation interposed between the two frames.

Thus, this solution offers effective and economical guidance of the metal plate, and makes it possible to preserve the tightness despite the high temperatures generated by the electrolytic cell in operation, thanks to the use of the means of compensation of expansion, such as flexible seals or brushes, allowing to absorb the dimensional variations of the frames and/or the metal plate while preserving the seal.

Advantageously, the electrical conductor is a non-deformable rigid electrical conductor. The mobile electrical conductor is not flexible and cannot be deformed so that the cooperation between the mobile electrical conductor and the sealing means is facilitated.

According to one embodiment, the anode assembly is supported by the second portion of the electrical conductor and moved via the electrical conductor.

Thus, the electrolytic cell can advantageously be free of a support device for the anode assembly other than the moving electrical conductor(s), such a device being liable to affect the tightness of the containment enclosure, for example. if it passes through this containment enclosure.

Advantageously, the electrolytic cell comprises moving means intended to move the electrical conductor in substantially vertical translation, the moving means being arranged entirely outside the containment enclosure.

The movement applied by the displacement means to the movable electrical conductor is then transmitted indirectly to the anode support via the non-deformable rigid movable electrical conductor.

Advantageously, the mobile electrical conductor is fixed to the displacement means outside the containment enclosure.

This configuration simultaneously offers the advantage of limiting the exposure of the moving means to high temperatures and to the gases generated by the electrolytic cell in operation with contained costs, while allowing the anode assembly to be moved indirectly, via the movable electrical conductor supporting it. The use of displacement means directly driving the anode assembly through the containment enclosure, affecting the tightness of the containment enclosure, can therefore be avoided. According to one embodiment, the displacement means are a jack associated specifically with the movable electrical conductor serving as a support for the anode assembly.

The moving electrical conductor performs three functions in its interactions with the anode assembly. It electrically connects the anode assembly to the electrical conductors arranged outside the containment enclosure, supports it and moves it.

The movable electrical conductor can be a one-piece or composite electrical conductor with, for example, a steel structure more dedicated to supporting the anode assembly and to transmitting the displacement, and a copper or aluminum structure more dedicated to electrical conduction.

Advantageously, the electrical conductor does not extend directly above said anode assembly, more particularly said anode support and anode block. In other words, the movable electrical conductor extends outside a volume obtained above the anode assembly by vertical translation of a projected surface of the anode assembly in a horizontal plane.

Thus, the movable electrical conductor is outside the vertical path of said anode assembly when it is withdrawn, so that no manipulation of the movable electrical conductor is necessary when changing the anode. This also makes it possible to prevent any risk of affecting the tightness of the confinement enclosure.

Advantageously, the electrical conductor is arranged under the anode support of the anode assembly.

Thus, the anode support can rest by gravity on the movable electrical conductor, so that the latter does not obstruct vertical withdrawal from above of the anode assembly, for example with a view to changing the anode.

No manipulation of the mobile electrical conductor is necessary during an operation to extract the anode assembly, which advantageously prevents any risk of affecting the tightness of the containment enclosure. Only a vertical repositioning of the mobile electrical conductor is carried out by the displacement means in order to be able to accommodate a new anode whose carbon height is much greater than a worn anode.

According to one embodiment, the upper portion of the confinement enclosure rests on the fixed portion of the confinement enclosure.

The fixed portion delimits a substantially horizontal rectangular opening and the upper portion rests substantially horizontally on the fixed portion.

Advantageously, the electrolytic cell comprises sealing means interposed between the upper portion and the fixed portion.

This contributes to improving the tightness of the containment enclosure at the junction between the removable upper portion and the lateral fixed portion which corresponds to a sensitive part of the containment enclosure.

According to one embodiment, the electrolytic cell comprises compression means intended to hold the upper portion pressed against the fixed portion.

Thus, the compression means make it possible to maintain the upper portion in contact with the fixed portion, to improve the tightness of the containment enclosure at the level of its junction between the removable upper portion and the lateral fixed portion.

This embodiment is all the more advantageous as sealing means are interposed between the upper portion and the fixed portion.

According to one embodiment, the upper portion comprises a plurality of adjacent covers that are substantially longitudinal and parallel to one another, extending in a direction that is substantially transverse to the electrolytic cell, between two opposite longitudinal edges of the electrolytic cell.

According to one embodiment, the electrolytic cell comprises means for fixing the anode support to the electrical conductor, the fixing means being entirely contained inside the containment enclosure.

This improves the electrical connection between the anode support and the corresponding electrical conductor.

The fixing means may comprise two complementary threads, the cooperation of which allows the fixing of the anode support and of the mobile electrical conductor by simple screwing.

The fixing means may comprise a screw connector performing compression of the anode support against the movable electrical conductor.

According to one embodiment, the electrolytic cell comprises several anode assemblies and, for each anode assembly, at least one electrical conductor electrically connected to the anode support.

According to one embodiment, the anode support comprises a bar which extends substantially horizontally between two opposite longitudinal edges of the electrolytic cell.

According to one embodiment, each of the opposite ends of the bar is electrically connected to an electrical conductor.

According to one embodiment, each of the opposite ends of the bar is supported by the second portion of an electrical conductor and moved via this electrical conductor.

According to one embodiment, the upper portion of the containment enclosure is designed to make it possible to extract the anode assembly by upward vertical translation of the anode assembly and to introduce the anode assembly by downward vertical translation of the anode assembly.

According to one embodiment, the fixed portion of the containment enclosure comprises a vertical part extending substantially vertically around and above the opening delimited by the box and the interior lining. This vertical part forms an interior volume allowing the movement of the anode assembly in the containment enclosure for the operation of the electrolytic cell. According to one embodiment, the mobile electrical conductor has a polygonal section portion.

Thus, rotation of the mobile electrical conductor around the axis in which it extends, relative to the sealing means, is prevented.

A non-claimed aspect relates to an aluminum smelter comprising at least one electrolytic cell having the aforementioned characteristics.

The aluminum smelter may comprise a plurality of electrolytic cells, among which said at least one electrolytic cell, forming a line, the electrolytic cells being arranged transversely with respect to the length of the line that they form.

• La figure 1 est une vue en coupe verticale, dans un plan transversal de la cuve d'électrolyse, d'une cuve d'électrolyse selon un mode de réalisation de l'invention,
• La figure 2 est une vue en coupe verticale, dans un plan transversal de la cuve d'électrolyse, d'une cuve d'électrolyse selon un mode de réalisation de l'invention,
• La figure 3 est une vue en coupe verticale, dans un plan transversal de la cuve d'électrolyse, d'une cuve d'électrolyse selon un mode de réalisation de l'invention,
• La figure 4 est une vue de côté d'une partie d'une cuve d'électrolyse selon un mode de réalisation de l'invention, dans un plan longitudinal de la cuve d'électrolyse,
• Les figures 5 et 6 sont des vues de côté d'une partie d'une cuve d'électrolyse selon un mode de réalisation de l'invention, dans un plan longitudinal de la cuve d'électrolyse, selon deux positions distinctes,
• La figure 7 est une vue en coupe selon la ligne I - I de la figure 5,
• La figure 8 est une vue en coupe selon la ligne II - II de la figure 5,
• La figure 9 est une vue en coupe selon un plan sensiblement horizontal d'un détail de la figure 3,
• La figure 10 est une vue en coupe verticale, dans un plan transversal de la cuve d'électrolyse, d'une cuve d'électrolyse selon un mode de réalisation de l'invention,
• La figure 11 est une vue en coupe verticale, dans un plan longitudinal de la cuve d'électrolyse, d'une cuve d'électrolyse selon un mode de réalisation de l'invention.

Other characteristics and advantages of the present invention will emerge clearly from the detailed description below of an embodiment of the invention, given by way of non-limiting example, with reference to the appended drawings in which:

• The figure 1 is a vertical sectional view, in a transverse plane of the electrolytic cell, of an electrolytic cell according to one embodiment of the invention,
• The picture 2 is a vertical sectional view, in a transverse plane of the electrolytic cell, of an electrolytic cell according to one embodiment of the invention,
• The picture 3 is a vertical sectional view, in a transverse plane of the electrolytic cell, of an electrolytic cell according to one embodiment of the invention,
• The figure 4 is a side view of part of an electrolytic cell according to one embodiment of the invention, in a longitudinal plane of the electrolytic cell,
• The figure 5 and 6 are side views of part of an electrolytic cell according to one embodiment of the invention, in a longitudinal plane of the electrolytic cell, according to two distinct positions,
• The figure 7 is a sectional view along line I - I of the figure 5 ,
• The figure 8 is a sectional view along the line II - II of the figure 5 ,
• The figure 9 is a sectional view along a substantially horizontal plane of a detail of the picture 3 ,
• The figure 10 is a vertical sectional view, in a transverse plane of the electrolytic cell, of an electrolytic cell according to one embodiment of the invention,
• The figure 11 is a vertical sectional view, in a longitudinal plane of the electrolytic cell, of an electrolytic cell according to one embodiment of the invention.

The figure 1 shows an electrolytic cell 1 according to one embodiment of the invention. The electrolysis tank 1 is intended for the production of aluminum by electrolysis.

It is specified that the description is carried out with respect to a Cartesian frame of reference linked to an electrolytic cell, the X axis being oriented in a transverse direction of the electrolytic cell, the Y axis being oriented in a longitudinal direction of the electrolytic cell, and the Z axis being oriented in a vertical direction of the electrolytic cell. The orientations, directions, planes and longitudinal, transverse and vertical movements are thus defined with respect to this reference system.

The electrolytic cell 1 is intended to be arranged transversely with respect to the length of a row of electrolytic cells to which it belongs. Thus, it extends lengthwise in the longitudinal direction Y while the row of electrolytic cells extends lengthwise in the transverse direction X.

As can be seen on the figures 1 to 3 , the electrolysis cell 1 comprises a box 2, which may be metallic, for example steel, and an interior coating 4, typically made of refractory materials. The box 2 is here provided with cradles 6 of reinforcements. The box 2 and its inner lining 4 delimits an opening across which are intended to extend a plurality of anode assemblies. These anode assemblies comprise an anode support 8 and at least one anode block 10 or anode, supported by the anode support 8. The anode support comprises for example a support bar 80, which can extend substantially horizontally between two opposite longitudinal edges of the electrolytic cell and the logs 81. The anode block 10 is more particularly attached to the anode support 8 at the means of logs 81 sealed with cast iron in holes provided for this purpose in the anode block 10.

The anode or anode block 10 is in particular made of carbonaceous material, and more particularly of the prebaked type. It is intended in operation to be immersed in an electrolytic bath 12 and to be consumed there. The anode assemblies are intended to be removed and replaced periodically as the anodes 10 wear out.

Due to the consumption of the anode blocks 10 as the electrolysis reaction progresses, the electrolytic cell 1 comprises means for moving the anode assemblies, making it possible to translate the anode assemblies substantially vertically only. These means of movement will be described in more detail below.

The electrolytic tank 1 comprises flexible electrical conductors 14 which can extend on either side of the electrolytic tank 1, as can be seen in particular on the picture 3 , at the two longitudinal edges of the cell 1 of electrolysis.

According to the example of figure 10 , the flexible electrical conductors 14 can extend from a single side of the electrolytic tank 1, at one of the two longitudinal edges of the electrolytic tank 1, also from bottom to top.

The flexible electrical conductors 14 are intended to conduct the electrolysis current to the anode blocks 10, from electrical conveying conductors (not shown) of a previous electrolytic cell in the line taking into account the overall direction of circulation of the electrolysis current, while accompanying and adapting by their flexibility to the movement in vertical translation of the anode assemblies. In other words, the flexible electrical conductor 14 has two ends which can move relative to each other vertically while providing a permanent electrical connection. The flexible electrical conductors 14 may correspond to a superposition of electrically conductive flexible sheets.

The electrolysis cell 1 also comprises a cathode 16, optionally formed of several cathode blocks of carbonaceous material, and traversed by cathode conductors 18 intended to collect the electrolysis current to conduct it towards cathode outputs 20 passing through the box 2 and connected to conveying conductors (not shown) in turn conducting the electrolysis current to the flexible electrical conductors 14 of a next electrolytic cell in the row.

The cathode conductors 18, the cathode outputs 20 and the routing conductors may correspond to metal bars, for example made of aluminium, copper or steel.

The electrolysis tank 1 comprises a containment enclosure 22 intended for the containment of the gases generated during the electrolysis reaction. This containment enclosure delimits a closed volume above the opening in the casing and the interior lining, through which an anode assembly is intended to be moved. This containment enclosure 22 can merge at least in part with the box and a superstructure of the electrolytic cell 1. The containment enclosure 22 comprises a movable upper portion 220 forming a cover, arranged above a fixed portion 230.

The fixed portion 230 comprises more particularly the casing 2 and a substantially vertical wall 231 extending around the opening above the casing 2. The substantially vertical wall 231 bears for example on the upper edges of the casing 2. The portion 230 fixed is advantageously rigid, the wall 231 being immobile relative to the box 2.

The upper portion 220 is removable to allow extraction of the anode assemblies by towing them in a substantially vertical manner from above above the electrolytic cell 1, as illustrated in the figure 11 . The fixed portion 230 forms an interior volume making it possible to extract the anode assembly by upward vertical translation of the anode assembly and to introduce the anode assembly by downward vertical translation of the anode assembly. An exclusively vertical movement of the anode assemblies above the opening encounters no obstacle.

It will be noted that the anode assemblies are entirely contained in the containment enclosure 22 .

The electrolytic cell 1 also comprises movable electrical conductors 26, intended to conduct the electrolysis current to the anode support 8, from the flexible electrical conductors 14 . The movable electrical conductors 26 comprise a second portion 260 disposed inside the containment enclosure 22 which is electrically connected to the anode assembly, in particular to the anode support 8, and more particularly to one end of the support bar 80 .

The movable electrical conductors 26 also include a first portion 262 disposed outside the containment enclosure 22 which is electrically connected to the flexible electrical conductors 14 .

The mobile electrical conductors 26 are advantageously rigid, non-deformable electrical conductors. The movable electrical conductors 26 may correspond, for example, to a metal support bar, in particular made of steel, copper, aluminum or a steel/copper composite.

The mobile electrical conductor or conductors 26 extend outside the casing 2, without extending in line with the opening delimited by the casing 2 and its interior coating 4, above the latter, so that the electrical connection between the mobile electrical conductor(s) 26 and the corresponding anode support 8 is necessarily made on one side of the electrolytic cell 1, but not above the opening delimited by box 2. Thus, as is visible on the figure 10 , no obstacle hinders the extraction of the anode blocks 10 above the cell 1 of electrolysis.

Thus, the mobile electrical conductors 26 make it possible to convey the electrolysis current from the outside of the enclosure 22 of confinement to the anode assembly contained entirely in the enclosure 22 of confinement.

The movable electrical conductors 26 are movable concomitantly with the anode assembly. Thus, they are intended to be translated substantially vertically as the anodes 10 are consumed.

The flexible electrical conductors 14 are arranged outside the containment enclosure 22 . Each flexible electrical conductor 14 is electrically connected to a movable electrical conductor 26 and adapts to the displacement of this movable electrical conductor 26 and of the associated anode assembly.

The second portion 260 of the mobile electrical conductors 26 extends inside the enclosure 22 of confinement, so that the electrical connection with the anode support 8 is made inside the enclosure 22 of confinement.

Thus, according to the invention, the anode assembly is exempt from any interaction with the confinement enclosure 22, so that this confinement enclosure 22 does not risk being affected either by the replacement of the anode assembly or by the displacement of the anode assembly downwards as the consumption of its or its anode blocks 10.

As shown on the figures 1 to 10 , the fixed portion 230 of the containment enclosure 22 has a window 232 through which extends one of the movable electrical conductors 26 which moves vertically. The first portion 262 of the movable electrical conductor 26 extends outside the enclosure 22 of confinement, while its second portion 260 extends inside the enclosure 22 of confinement. In other words, the movable electrical conductor 26 passes through the fixed portion 230 of the enclosure 22 of containment.

The electrolysis cell 1 then advantageously comprises sealing means to prevent the gases generated during the electrolysis reaction from leaving the containment enclosure 22 via the window 232 through which the movable electrical conductor 26 passes.

According to the examples of figure 1 , 3 , 9 and 10 , the mobile electrical conductors 26 pass through the fixed portion 230 of the containment enclosure 22, and more particularly the window 232, in a substantially vertical manner and move vertically in translation.

The part of the fixed portion 230 of the containment enclosure traversed vertically by the mobile electrical conductor 26 is a horizontal part which extends substantially horizontally. This horizontal part of the containment enclosure 22 may for example be a flat area on the upper edges of the casing 2 or a horizontal wall attached to the upper edges of the casing 2. The first portion 262 of the movable electrical conductor extending to the exterior of the containment enclosure is arranged below the part of the fixed portion 230 of the containment enclosure 22 through which the movable electrical conductor 26 passes vertically, while the second portion 260 of the movable electrical conductor 26 is extending inside the containment enclosure 22 is arranged above. In other words, the mobile electrical conductor 26 passes through the fixed portion from the bottom upwards from its first exterior portion 262 to its second portion 260 inside the containment enclosure. The length of the electrical electrolysis circuit is then minimized.

The sealing means here comprise a dynamic seal 32 surrounding the electrical conductor 14 moving in vertical translation.

This annular dynamic seal 32 may for example consist of metal strips, brushes or a flexible or elastic material resistant to temperature and gases. Furthermore, these seals 32 will exhibit very low aging because they are not exposed to shocks.

The movable electrical conductor 26 comprises between the second portion 260 and the first portion 262 a sealing portion 261 intended to cooperate with the seal 32. This sealing portion is advantageously rectilinear and of constant section, so as to improve sealing and facilitate the design of the dynamic seal.

According to the example of figure 2 and 4 to 8 , the movable electrical conductors 26 pass through the fixed portion 230 of the containment enclosure 22, and more particularly the window 232, substantially horizontally and move vertically in translation. The window 232 is more particularly formed in a part or wall 231 substantially of the fixed portion 230.

The sealing means then comprise a sealing member 34 configured to completely close the window 232 of the fixed portion, regardless of the position of the mobile electrical conductor 26 through the window 232.

Indeed, the movable electrical conductors 26 are movable, with the anode assembly, between a first position, or high position ( figure 5 ), corresponding in particular to a position in which the anode assembly comprises a new anode block 10, and a second position, or low position ( figure 6 ), corresponding in particular to a position in which the anode block 10 is worn and must be replaced. The difference between these two positions defines a vertical deflection d of the movable electrical conductor 26 to be allowed by the window 232 and the sealing means.

As illustrated in the figure 5 , the sealing member 34 surrounds the movable electrical conductor 26 with which it is associated. In addition, the sealing member 34 is mounted integral with this movable electrical conductor 26. Thus, the sealing member 34 may for example comprise two parts between which the movable electrical conductor 26 is intended to be inserted, and fixing means, such as screws 36, for fixing the two parts to one another. other.

As illustrated in the figures 4 to 8 , the sealing member 34 may correspond to a metal plate extending in a plane substantially parallel to the plane in which the adjacent fixed portion 230 extends.

Still following the example of figures 4 to 8 , a compensation member 38 can be arranged between the metal plate and the movable electrical conductor 26 that it surrounds.

The electrolytic cell 1 can further comprise means for guiding this metal plate in translation. The guide means comprise for example two substantially rectangular frames 40, fixed against the fixed portion 230 of the containment enclosure 22 so as to surround the window 232, for example by means of screws 41, and arranged one by relative to each other to delimit between them a space within which the metal plate is intended to slide. The electrolytic cell 1 can also comprise expansion compensation means interposed between the two frames, such as a flexible seal allowing it to be compressed sufficiently to bring the sealing member 34 and the frames 40 into contact, and this for seal while allowing sliding between the sealing member 34 and the frames 40.

As can be seen on the figures 5 to 8 and on the figure 9 , the mobile electrical conductor 26 may have a portion with a polygonal section, for example a square or rectangular section, in particular at the passage of the confinement enclosure, so that a rotation of the mobile electrical conductor 26 around the axis in which it stretches, relative to the sealing means, is prevented.

It will be noted that the anode assembly can be fully supported at each of the ends of the support bar 80 by the second portion 260 of the mobile electrical conductor(s) 26, so that no additional support device capable of interacting with the containment enclosure 22 is not necessary.

The mobile electrical conductors 26 thus provide both an electrical connection function with the anode assembly and a mechanical support function for the anode assembly ensuring the movement of the anode assembly.

The electrolytic cell 1 may comprise several movable electrical conductors 26 electrically connected to the same anode support 8, the second portions 260 of these movable electrical conductors 26 supporting the anode assembly. For example, as shown in the figure 1, 2 Where 3 , the electrolytic cell 1 may comprise, for each anode support 8, two movable electrical conductors 26, one and the other arranged at two opposite sides of the electrolytic cell 1. It will be noted that each anode support 8 may comprise an upstream end 82 electrically connected and supported by the second portion 260 of an upstream mobile electrical conductor 26, and a downstream end 83 electrically connected and supported by a downstream mobile electrical conductor 26 .

It is specified that upstream/downstream are defined with respect to the overall direction of circulation of the electrolysis current in the row of electrolytic cells.

According to the example of figure 10 , the electrolytic cell 1 comprises, for each anode support 8, a single movable electrical conductor 26, arranged at one of the two sides of the electrolytic cell 1. Where appropriate, it is the upstream end 82 which is advantageously electrically connected and supported by the movable electrical conductor 26, in order to minimize the overall length of the electrolysis conductor circuit.

As stated previously, the mobile electrical conductor(s) 26 are mobile with the anode assembly to which they are electrically connected.

Furthermore, it has also been specified that the moving electrical conductors 26 can advantageously fully mechanically support the anode assembly to which they are electrically connected.

To move the anode assembly, the electrolytic cell 1 may comprise moving means which are advantageously arranged to move the mobile electrical conductor or conductors 26, according to a vertical translational movement.

This configuration, which consists in moving the anode assembly not directly but via the mobile electrical conductor(s) 26, makes it possible to arrange the means of movement outside the containment enclosure 22, which limits potential interactions with the containment enclosure 22 while limiting the exposure of the displacement means to high temperatures and to the gases generated by the electrolytic cell 1 in operation. For example, as shown in the picture 3 , the displacement means comprise a separate jack 42 per mobile electrical conductor 26, of which a movable end is attached to the first portion 262 of one of the movable electrical conductors 26 supporting the anode assembly. A fixed part of the actuator 42 can be attached to a fixed element, for example to the fixed portion 230 of the containment enclosure 22, in particular to the box 2 or to the wall 231. Each mobile electrical conductor 26 is set in motion by separate displacement means and more particularly a separate cylinder 42. The means of displacement of the various anode assemblies are therefore distinct.

According to the example of figure 10 , showing an electrolytic tank 1 with mobile electrical conductors 26 arranged on a single side of the electrolytic tank 1, the displacement means may comprise, on this side of the electrolytic tank 1 and similarly, a jack 42, one end of which is attached to the fixed portion 230 of the containment enclosure 22, while the end of the jack 42 is attached to the first portion 262 of the corresponding mobile electrical conductor 26 supporting the anode assembly. On the other side of the electrolytic cell 1, that is to say the side free of a mobile electrical conductor 26, the displacement means may comprise a jack 43 and a remote mobile support 45, guided vertically and supporting the anode assembly. Sealing means similar to those previously described can be provided around the support 45.

It will be noted that the second portion 260 of each movable electrical conductor 26 can be arranged under the anode support 8 of the anode assembly, so that the latter can rest by gravity on the second portion 260 of the movable electrical conductors 26 .

In addition, the mobile electrical conductor(s) 26 can extend under the anode support 8 of the anode assembly without extending above and in line with the corresponding anode assembly.

This allows replacement of the anode assembly without the mobile electrical conductors 26 obstructing this replacement, therefore by a simple lifting movement of the anode assembly and without manipulation of the mobile electrical conductors 26 which could be detrimental to the sealing of the containment enclosure 22.

To improve the tightness of the containment enclosure 22, more particularly at the level of the junction between the removable upper portion 220 and the side fixed portion 230, provision may be made for the electrolytic cell 1 to comprise sealing means interposed between the upper portion 220 and the fixed portion 230 on which the upper portion 220 rests at least in part. The sealing means can include a static seal 44 interposed between the upper portion 220 and the fixed portion 230.

Furthermore, the electrolytic cell 1 may comprise compression means, such as a screw system, intended to hold the upper portion 220 pressed against the fixed portion 230.

As can be seen on the figure 4 and 11 , the upper portion 220 may comprise a plurality of adjacent covers 222 that are substantially longitudinal and parallel to one another, extending along a direction X that is substantially transverse to the electrolytic cell 1, between two opposite longitudinal edges of the electrolytic cell 1.

The support means correspond for example to beams 46 extending along the substantially transverse direction X of the electrolytic cell 1. These beams 46 can be part of the superstructure.

They make it possible to avoid warping of the covers 222 which could affect the tightness of the enclosure 22 of containment.

It will be noted that the beams 46 can also support ancillary devices such as tapping and feeding devices.

The invention also relates to an aluminum smelter comprising at least one electrolytic cell 1 according to the invention.

The electrolytic cells of this aluminum smelter form a row, and are arranged transversely with respect to the length of this row.

Of course, the invention is in no way limited to the embodiment described above, this embodiment having been given only by way of example. Modifications are possible, in particular from the point of view of the constitution of the various elements or by the substitution of technical equivalents, without thereby departing from the scope of protection of the invention as defined by the claims.

Claims (18)

1. An electrolytic cell (1), intended for the production of aluminum by electrolysis, comprising a pot shell (2) including an inner liner (4) delimiting an opening, a confinement chamber (22) delimiting a closed volume above said opening intended for the confinement of the gases generated during the production of aluminum, an anode assembly movable relative to the pot shell (2) and intended to be removed and replaced periodically, the anode assembly comprising an anode support (8) from which at least one anode block (10) intended to be moved through said opening during the production of aluminum is suspended, and a movable electrical conductor (26) and is electrically connected to the anode assembly via the anode support (8) to bring an electrolysis current to said at least one anode block (10) during the displacement of the anode block (10), the anode assembly being fully contained in the volume delimited by the confinement chamber (22), the electrical connection between the movable electrical conductor (26) and the anode support (8) being made inside the volume delimited by the confinement chamber (22), characterized in that the movable electric conductor (26) extends in the volume delimited by the confinement chamber (22) outside a volume defined by the top of the anode block (10) when moving the anode block (10) through the opening.
2. The electrolytic cell (1) according to claim 1, characterized in that the confinement chamber (22) comprises an upper portion (220) forming a lid, said upper portion (220) being removable to allow extraction of the anode assembly.
3. The electrolytic cell (1) according to claim 1 or 2, characterized in that the confinement chamber (22) includes a fixed portion (230) which has a window (232) through which the movable electrical conductor (26) extends, the movable electrical conductor (26) comprising a first portion (262) extending outside the volume delimited by the confinement chamber (22) and a second portion (260) extending inside the volume delimited by the confinement chamber (22) and to which the anode support (8) is electrically connected.
4. The electrolytic cell (1) according to claim 3, characterized in that the electrolytic cell (1) comprises sealing means to prevent gases generated during the electrolysis reaction from leaving the volume delimited by the confinement chamber (22) via the window (232) through which the movable electrical conductor (26) passes.
5. The electrolytic cell (1) according to claim 4, characterized in that the movable electrical conductor (26) passes through the fixed portion (230) of the confinement chamber (22) in a substantially vertical manner, and the sealing means comprise a dynamic seal (32) surrounding the movable electrical conductor (26).
6. The electrolytic cell (1) according to claim 5, characterized in that the movable electrical conductor (26) passes through a horizontal part of the fixed portion (230).
7. The electrolytic cell (1) according to claim 6, characterized in that the movable electrical conductor (26) passes through the fixed portion (230) of the confinement chamber (22) in a substantially horizontal manner, and the sealing means comprise a sealing member (34) configured to completely close the window (232) of the fixed portion (230), regardless of the position of the movable electrical conductor (26) through the window (232).
8. The electrolytic cell (1) according to claim 7, characterized in that the sealing member (34) surrounds the movable electrical conductor (26) and is mounted solid with the movable electrical conductor (26).
9. The electrolytic cell (1) according to any of claims 1 to 8, characterized in that the anode assembly is supported by the electrical conductor (26) and moved via the electrical conductor (26).
10. The electrolytic cell (1) according to claim 9, characterized in that the electrolytic cell (1) comprises moving means intended to move the electrical conductor (26) in substantially vertical translation, the moving means being arranged fully outside the volume delimited by the confinement chamber (22).
11. The electrolytic cell (1) according to any of claims 1 to 10, characterized in that the electrical conductor does not extend to the right above said anode assembly.
12. The electrolytic cell (1) according to claim 11, characterized in that the electrical conductor (26) is arranged under the anode support (8) of the anode assembly.
13. The electrolytic cell (1) according to any of claims 3 to 12, characterized in that the fixed portion (230) of the confinement chamber (22) delimits a substantially horizontal rectangular opening and the upper portion (220) of the confinement chamber rests substantially horizontally on the fixed portion (230).
14. The electrolytic cell (1) according to claim 13, characterized in that the fixed portion (230) of the confinement chamber (22) comprises a vertical part extending substantially vertically around and above the opening delimited by the pot shell (2) and the inner liner (4).
15. The electrolytic cell (1) according to any of claims 1 to 14, characterized in that the electrolytic cell (1) comprises means for fixing the anode support to the electrical conductor (26), the fixing means being fully contained inside the confinement chamber (22).
16. The electrolytic cell (1) according to any of claims 1 to 15, characterized in that the electrolytic cell (1) comprises several anode assemblies and, for each anode assembly, at least one electrical conductor (26) electrically connected to the anode support (8).
17. The electrolytic cell (1) according to any of claims 1 to 16, characterized in that the anode support (8) comprises a bar (80) extending in a substantially horizontal manner between two opposite longitudinal edges of the electrolytic cell (1).
18. The electrolytic cell (1) according to claim 17, characterized in that each of the opposite ends of the bar (80) is electrically connected to an electrical conductor (26).

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