AU2019202943B2 - Device for storing a load above an electrolytic cell - Google Patents

Abstract

DEVICE FOR STORING A LOAD ABOVE AN ELECTROLYTIC CELL Storage device (1) for a load above an electrolytic cell (100) comprising a pot shell (102), hoods (120), a cathode (104) and anode assemblies(106) arranged in the pot shell (102) and covered by the hoods (120), the load storage device (1) comprising support means on which the load to be stored above the electrolytic cell (100) is designed to rest on, and bearing means designed so that the support means rest stably above the electrolytic cell (100), particularly above the anode assemblies (106) and the hoods. Figure 2 WO 2015/110902 PCT/IB2015/000069 X Y 100 2 1 6 2 4 x * 12 10 1 60 1 108 F10 202 10,l 106a1 Fig 1 1002 161 1 ,06 100 106 4106,106a Z2 1001 1080 120 1)!:dX-< y 118 Fig. 2 1 02 106b 110 104 1 a 101 1 b 100 Fig. 3 116

Description

DEVICE FOR STORING A LOAD ABOVE AN ELECTROLYTIC CELL

This application is a divisional application of Australian Patent Application No. 2015208856, filed on 12 July 2016, which is incorporated herein by reference in its entirety. The present invention relates to a device for storing a load for an electrolytic cell, a storage system comprising this device, an electrolytic cell and an electrolysis plant comprising this device, together with a method for changing an anode assembly using this storage device.

Aluminum is conventionally produced in aluminum works by electrolysis using the Hall-Heroult process.

An aluminum works traditionally includes hundreds of electrolytic cells connected in series and carrying an electrolysis current that may be as much as hundreds of thousands of amperes. The electrolytic cells are arranged transversely in relation to the flow direction of the electrolysis current across the series. Two adjacent electrolytic cells in the series are separated by an aisle between the cells. A broader operating aisle substantially perpendicular to a longitudinal direction of the cells and aisles between the cells, extends along the series to allow access and movement of vehicles and personnel on foot.

Electrolytic cells conventionally comprise a steel pot shell within which there is a lining of refractory materials, a cathode of carbon material, through which pass cathode conductors designed to collect the electrolysis current at the cathode to route it to the cathode outputs which pass through the bottom or sides of the pot shell, linking conductors extending substantially horizontally to the next cell from the cathode outputs, an electrolyte bath in which the alumina is dissolved, at least one anode assembly comprising at least one anode immersed in this electrolyte bath and an anode rod sealed in the anode, an anode frame on which the anode assembly is suspended via the anode rod, and risers for the electrolysis current running upwards connected to linking conductors from the preceding electrolytic cell to route the electrolysis current from the cathode outputs to the anode frame and the anode assembly and anode in the next cell. The anodes are more particularly of the pre-baked anode type with prebaked carbon blocks, i.e. baked before they are placed in the electrolytic cell.

The pot shell includes edges defining an opening through which the anode assemblies are inserted into the electrolytic cell.

To limit heat loss and prevent the gases generated during the electrolysis reaction from diffusing outside the electrolytic cell, provision is made to close the opening defined by the pot shell with a set of removable hoods resting laterally on the edges of the electrolytic cell and against a superstructure traditionally extending above the opening defined by the pot shell. These hoods are generally juxtaposed alongside each other along a longitudinal direction of the electrolytic cell so as to form a closed chamber.

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2019202943 23 Apr 2020

However, the anode assemblies are consumed during the electrolysis reaction and must therefore be replaced with new anode assemblies. During a change of anode assembly, some of the hoods are removed to open a window giving access to the inside of the electrolytic cell.

The spent anode assembly is removed from the electrolytic cell through the access window and deposited on a support. The extracted spent anode assembly is temporarily stored on the support before being taken to a recycling area.

The crusts formed by covering products periodically introduced into the electrolytic bath are removed and placed in a crust collection device (or crust bin) with a cleaning tool also called a crust shovel. This tool is inserted into the electrolytic cell through the access window. A new anode assembly is then introduced into the electrolytic cell via the access window, in place of the spent anode assembly. Finally, the initially removed removable hoods are replaced to close the access window. While the anode assembly is being changed, the access window remains open.

During these steps, the anode devices and assemblies required to change an anode assembly such as the new anode assembly, the spent anode assembly support and the crust collecting device are temporarily stored near the electrolytic cell for which this change of anode assembly is to be carried out.

Publication EP0298198 discloses an anode storage module attached to a traveling crane and inserted in an aisle between cells opposite the spent anode assembly to be replaced. Such equipment is complex to implement, use, position and move due to the very small size of the aisles between cells and the large number of interlocking pieces of mobile equipment needed to change an anode assembly.

Also, given the limited dimensions of the aisles between cells, which are as narrow as possible to bring the electrolytic cells close to each other, it is customary to store new and spent anode assemblies and equipment necessary for changing an anode assembly in the operating aisle, near the transverse edges of the pot shell of the electrolytic cell.

However, this storage solution obstructs the operating aisle. This means that it is necessary to provide a wider operating aisle, leading therefore to increased structural costs (buildings, civil engineering, etc.) and/or hindering the movement of vehicles and staff. The visibility off staff or vehicle drivers may be hidden, which requires additional safety measures.

It should also be noted that this storage area is far from the work area. This storage area is located at one end of the electrolytic cell.

Pot tending machines, such as a handling crane, used to move new and spent anode assemblies, and devices such as crust shovels, therefore travel a large distance between their storage area at the end of the cell and the operating area.

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2019202943 23 Apr 2020

In addition, the various successive stages of the anode assembly change process require several return trips between the operating area and the operating aisle where the storage area is located. The distance traveled by the pot tending machine for an outward or a return trip and the number of successive round trips determine the operating time during which the access window remains open.

But the longer the access window remains open, the greater the heat losses or gas leaks.

This gaseous pollution, these energy losses and the size of the operating aisle can affect the performance of the aluminum works.

It is an object of the present invention to substantially overcome or ameliorate one or more of the above disadvantages, or at least provide a useful alternative.

In accordance with an aspect of the present disclosure, there is provided a storage device for a load above an electrolytic cell comprising a pot shell, hoods, a cathode and anode assemblies arranged in the pot shell and covered by the hoods, the load storage device comprising support means on which the load to be stored above the electrolytic cell is designed to rest in a volume formed by vertical translation of a surface obtained by projecting the electrolytic cell in a horizontal plane, and bearing means designed so that the support means rest stably above the electrolytic cell, particularly above the anode assemblies and the hoods.

In accordance with a further aspect of the present disclosure, there is provided an electrolytic cell comprising a pot shell, hoods, a cathode and anode assemblies arranged inside the pot shell and covered by the hoods, and a storage device according to the preceding aspect, said storage device extending above the electrolytic cell.

In accordance with further aspect of the present disclosure, there is provided a method for changing a spent anode assembly in an electrolytic cell for a new anode assembly, comprising a step of setting up a storage device according to the foremost aspect above the electrolytic cell.

Also disclosed is a storage device for a load above an electrolytic cell comprising a pot shell, hoods, a cathode and anode assemblies arranged in the pot shell and covered by the hoods, the load storage device comprising support means on which the load to be stored above the electrolytic cell is designed to rest on, and bearing means designed so that the support means rest stably above the electrolytic cell, particularly above the anode assemblies and the hoods.

Preferably, in this way, the storage device makes it possible to arrange a temporary storage space above an electrolytic cell, and more particularly above the anode assemblies and the hoods.

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3a

2019202943 23 Apr 2020

Throughout the description and the claims, the term above a component mean above this component in a volume formed by vertical translation of the surface obtained by projecting this component in a horizontal plane.

The storage space being above the electrolytic cell, the operating aisle is no longer obstructed.

Preferably, in addition, the storage device allows accurate positioning of the removable hood(s) which will be removed to create an access window during work on

24473156 a cell such as changing an anode assembly.

This results in a smaller distance traveled by the pot tending machine during this operation and while the access window is open, in comparison with prior art.

This gives a shorter operation time, in particular for changing an anode assembly, and also a shorter opening time for the window giving access to the electrolytic cell.

Heat losses and gas leaks are limited.

According to a preferred embodiment, the support means comprise one or more supporting surfaces adapted to support a new anode assembly, a spent anode assembly and/or a device for collecting crusts formed during an electrolytic reaction.

The load is therefore more particularly a new anode assembly, a spent anode assembly and/or a device for collecting crusts formed during an electrolytic reaction.

The storage device is therefore suitable for use in connection with a change of anode assembly.

Advantageously, the support means comprise means for preventing the supported load from slipping or falling.

This reduces the risk of the supported load slipping and accidentally falling, which could cause significant damage to the electrolytic cell located under the storage device.

Advantageously, the support means include an anticorrosion means such as an anticorrosion medium or coating.

The support means are therefore particularly adapted to receive a spent anode assembly from out of the electrolytic bath, and have improved durability.

According to an advantageous embodiment, the storage device comprises handling means to enable it to be handled by moving means.

In this way, the storage device may be moved to be positioned above the electrolytic cell where a load is to be temporarily stored.

The moving means may include a handling machine or a handling crane, usually known as a pot tending machine.

The storage device is therefore mobile and easy to use for the temporary load storage associated with an operation on a cell such as changing an anode assembly.

The handling means may be advantageously shaped to permit raising of the storage device.

Raising makes it possible not only to position the storage device above the electrolytic cell, moving the storage device along the electrolytic cell to position it as close as possible to the target area, but also optionally to position a storage device over an electrolytic cell adjacent to the one where the anode assembly change is to be performed.

According to a preferred embodiment, the support means are in the shape of a substantially flat plate, arranged to extend in a substantially horizontal plane.

This simple solution makes it possible to quickly deposit a load, without worrying about putting it in a specific location. This saves time, thereby reducing the time that the electrolytic cell remains open.

Advantageously, the plate has two opposite transverse edges, and the support means extend exclusively from the two transverse edges.

In this way, the bearing means define between them a space that can substantially correspond to the length of the plate.

Advantageously, the bearing means extend substantially straight and perpendicular to the plate.

This ensures better transmission of the weight of the plate and the load or loads that are put on it.

Preferably the bearing means have one end connected to an underside of the support means.

This feature gives greater strength to the storage device or, if appropriate, to the storage devices.

According to one possibility, the plate has reinforcing means to limit its bending under the effect of the weight of a load.

The support means are thereby more robust and more resistant to bending. This prevents part of the support means from coming into contact, due to significant bending, with the hoods of the electrolytic cell, which may deform these hoods.

Advantageously, the reinforcement means comprise two flanges extending along the longitudinal edges of the plate.

Preferably, the support means have an underside provided with thermal insulation means.

In this way, the support means will bend less under the effect of the temperature above the electrolytic cell.

According to an advantageous embodiment, the support means comprise two concave

2019202943 26 Apr 2019 housings, interdependent with the support means, and designed for an anode assembly to hang from them.

In this way, the support means make it possible to hang an anode assembly from them. This has the advantage of being able to move the storage device and the anode assembly that the storage device supports, with a lower risk of falling.

Advantageously, the storage device includes spacer means for making the two concave housings interdependent.

This makes the support means more stable.

Also disclosed is a storage system comprising multiple separate and independent storage devices, having the aforesaid characteristics, suitable for storing above the electrolytic cell a new anode assembly, a spent anode assembly and a device for collecting crusts formed during an electrolytic reaction.

Preferably, this gives an advantageous spatial arrangement, insofar as two separate storage devices can be placed on either side of the access window arranged to replace an anode assembly.

Preferably, this arrangement therefore offers shorter distances between the operating area and the storage space, so that the time required to change an anode assembly is limited.

In a preferred embodiment, the storage system includes three storage devices, including a first storage device for supporting the new anode assembly, a second storage device for supporting the spent anode assembly, and a third storage device for supporting the crust collection device.

The new anode assembly, the spent anode assembly and the crust collecting device therefore each have a dedicated storage device.

This gives an even more advantageous spatial arrangement, because each of these three components necessary for changing an anode assembly can be placed as close as possible to the access window during the anode assembly change.

Two of the three storage devices may be positioned on either side of the access window, while the remaining storage device may be positioned above an electrolytic cell adjacent to the one for which the anode change is to be performed, facing the access window.

In other words, this embodiment allows a staggered or triangular arrangement of the storage devices, so that the period during which the electrolytic cell is open can be substantially reduced.

AH25(22598399_1):MSD

2019202943 26 Apr 2019

Also disclosed is an electrolytic cell comprising a pot shell, hoods, a cathode and anode assemblies arranged inside the pot shell and covered by the hoods, and a storage device having the above characteristics, said storage device extending above the electrolytic cell.

Preferably, in this way, the electrolytic cell associated with the storage device offers the possibility of storing a load above anode assemblies and hoods, which limits the space required around the electrolytic cell.

According to a preferred embodiment, the storage device is arranged above the anode assemblies in place inside the pot shell and the hoods arranged above these anode assemblies.

In other words, the storage device is arranged above the anode assemblies in production and closed hoods keeping the gases above the anode assemblies contained.

The hoods close an opening in the electrolytic cell through which the anode assemblies are designed to be inserted or extracted inside or outside of the pot shell, and the storage device is arranged above the hoods of the electrolytic cell.

According to a preferred embodiment, the electrolytic cell comprises two opposite longitudinal sides and the storage device extends between the two opposite longitudinal sides.

According to a preferred embodiment, the electrolytic cell comprises a substantially parallelepiped confinement chamber resting on the edges of the pot shell, the confinement chamber forming a confinement volume inside which the anode assemblies are designed to move during the electrolysis reaction, and the storage device extends between two opposite longitudinal top edges of the confinement chamber.

According to a preferred embodiment, the bearing means rest on the opposite longitudinal upper edges of the confinement chamber and these edges are advantageously formed by a sleeve for capturing gases from the cell.

This reinforces the mechanical load strength of these edges.

According to a preferred embodiment, the bearing means comprise bearing surfaces designed to bear against a fixed structure of the electrolytic cell.

In other words, the bearing surfaces advantageously do not bear on the hoods of the electrolytic cell.

This advantageously limits the strain on the hoods in terms of load. The supports of the hoods are located at their transverse sides, and more particularly at the longitudinal edges of the electrolytic cell, so that they can bend under the effect of the weight of a load. The bending of a

AH25(22598399_1):MSD

2019202943 26 Apr 2019 hood relative to an adjacent hood may create an opening between these two hoods that can lead to heat losses and gas leaks.

According to a preferred embodiment, the fixed structure comprises reinforcement means designed to allow the fixed structure to support the weight of the storage device and optionally of the load supported by the storage device.

Advantageously, the electrolytic cell comprises at least two counter-bearing surfaces on which the bearing surfaces of the storage device are designed to rest, both counter-bearing surfaces being arranged on either side of a longitudinal median plane of the electrolytic cell.

This feature provides stable support for the storage device.

Preferably, both counter-bearing surfaces are arranged on the longitudinal sides of the electrolytic cell.

In this way, the storage device, and as appropriate the storage devices, extend in a transverse direction Y of the electrolytic cell.

According to an advantageous embodiment, the electrolytic cell comprises at least two counterbearing surfaces on which the bearing surfaces of the storage device are designed to rest, and the bearing surfaces and counter-bearing surfaces include interlocking means designed to work in conjunction by the complementarity of their shape.

This allows precise positioning of the storage device and prevents slippage of the storage device.

Preferably, the support means extend away from the hoods of the electrolytic cell.

The lack of contact between the hoods and the support means advantageously prevents part of the load supported by the support means from being transmitted to the hoods.

Advantageously, the anode assembly includes an anode support extending in a transverse direction of the electrolytic cell.

In other words, the anode assembly does not have a vertical rod, as in prior art, which makes it possible to reduce the height of the anode assembly. This avoids the need to oversize the storage device, thereby limiting costs, and making it possible to use this storage device easily.

Also disclosed is an electrolysis plant, especially an aluminum works comprising a series of electrolytic cells, including one electrolytic cell and at least one storage device having the above characteristics, and an operating aisle extending substantially parallel to the series of electrolytic cells.

AH25(22598399_1):MSD

2019202943 26 Apr 2019

Preferably, this electrolysis plant has reduced spatial requirements and lower operating costs than existing electrolysis plants.

In particular, this electrolysis plant has shorter distances for pot tending machines handling the load to travel, and therefore a substantially shorter open time when an access window is formed through the hoods for access to the inside of the electrolytic cell.

According to a preferred embodiment, the support means comprise bearing surfaces designed to bear against a surface of an aisle between cells along a longitudinal edge of the electrolytic cell and separating said electrolytic cell from an adjacent electrolytic cell.

In other words, the counter-bearing surfaces are located within the aisles between cells separating the longitudinal sides of two adjacent electrolytic cells in the series of electrolytic cells. More particularly, the counter-bearing surfaces of a storage device are located on the interior of two different aisles between cells, on either side of the electrolytic cell above which the storage device is placed.

According to a preferred embodiment, the support means define a space between them such that the electrolytic cell extends between the bearing means of the storage device.

The storage device therefore spans the electrolytic cell.

According to one embodiment, the electrolysis plant comprises moving means designed to move the storage device in a substantially longitudinal direction of the electrolytic cell.

According to one advantageous possibility, the moving means comprise a handling machine or a handling crane for lifting the storage device.

In this way the same storage device can be used for several electrolytic cells.

In particular, when the electrolysis plant has a storage system with multiple storage devices, one of these storage devices may be arranged on an adjacent cell to the cell where a change of anode assembly is to take place, specifically facing the part of the cell in which the change of anode assembly is to take place.

Also disclosed is a method for changing a spent anode assembly in an electrolytic cell for a new anode assembly, comprising a step of setting up a storage device having the above characteristics above the electrolytic cell.

Preferably, this method reduces the time taken to change the anode assembly, and therefore the time during which a window giving access to the inside of the electrolytic cell is open. This reduces heat losses and leakage of gas.

AH25(22598399_1):MSD

According to an advantageous embodiment, the setting-up step comprises positioning the storage device in line with one or more anode assemblies, close to, and preferably adjacent to the spent anode assembly.

This feature minimizes the distances traveled by a pot tending machine designed to handle the components necessary to change the anode assembly, including the spent anode assembly and the new anode assembly.

In line with an anode assembly is taken to mean within a volume formed by the vertical translation of the surface obtained by projection of this anode assembly in a horizontal plane.

The storage device is not positioned in line with the spent anode assembly used in order to allow this spent anode assembly to be extracted through the top, i.e. to be extracted by substantially vertical upward translation of the spent anode assembly and to enable the new anode assembly to be inserted from the top, i.e. a set-up by substantially vertical downward translation of the new anode assembly.

According to one embodiment, the method is implemented by means of a storage system comprising a plurality of separate storage devices, and the method comprises a step of positioning one of the storage devices of the storage system above an electrolytic cell adjacent to the electrolytic cell comprising the spent anode assembly.

This feature makes it possible to further reduce the time taken for the anode assembly change, allowing a substantially staggered or triangular arrangement of the storage devices around the spent anode assembly to be replaced.

According to a preferred embodiment, the method comprises steps consisting in forming an access window between the hoods of the electrolytic cell to extract the spent anode assembly and replace it with a new anode assembly and arranging said storage device facing the access window.

In other words, this storage device is arranged substantially symmetrically to the access window with respect to the aisle between cells separating the electrolytic cell with the spent anode assembly from the electrolytic cell above which the storage device is positioned.

This arrangement gives the shortest distance between the storage device and the access window.

According to a preferred embodiment, the method comprises a step involving forming an access window between the hoods of the electrolytic cell to extract the spent anode assembly and replace it with a new anode assembly and the method includes performing a change of anode assembly by means of a pot tending machine moving only between the transverse sides of the electrolytic cell comprising the spent anode assembly and optionally of an electrolytic cell adjacent to said electrolytic cell comprising the spent anode assembly throughout the period during which the access window is formed between the hoods of the electrolytic cell to extract the spent anode assembly and replace it with a new anode assembly.

In other words, the pot tending machine does not move as far as the operating aisle along one transverse side of the electrolytic cell during this entire period.

Other characteristics and advantages of this invention will be clearly apparent from the following description of an embodiment provided by way of a non-limiting example with reference to the appended drawings, in which:

- figure 1 is a perspective view of a storage device according to one embodiment of the invention,

- figure 2 is a cross-sectional view along a vertical longitudinal plane XZ of an electrolytic cell according to one embodiment of the invention,

- figure 3 is a perspective view of a storage device according to one embodiment of the invention,

- figures 4 to 11 are perspective views of an electrolytic cell according to one embodiment of the invention, illustrating the steps of a method for changing an anode assembly according to one embodiment of the invention,

- figures 12 and 13 are top views of a storage device according to one embodiment of the invention, respectively without and with an anode assembly,

- figure 14 is a side view of a storage device according to one embodiment of the invention.

Figure 1 shows part of an electrolysis plant comprising an electrolytic cell 100 and a storage device 1 according to one embodiment of the invention.

Electrolytic cell 100 is designed for the production of aluminum by electrolysis.

The storage device is designed to temporarily store a load above the electrolytic cell 100.

The electrolytic cell 100 comprises a pot shell 102, hoods 120, a cathode 104 and anode assemblies 106 arranged inside the pot shell 102 and covered by the hoods. The storage device 1 will be described in more detail below.

The electrolytic cell 100 comprises a fixed structure. The fixed structure comprises the pot shell 102 and, as appropriate, parts of a confinement chamber 108 designed to confine the gases generated during the electrolysis reaction.

The anode assemblies 106 are movable in a substantially vertical translation relative to the fixed structure of the electrolytic cell so as to be immersed in an electrolytic bath 110 as they are used up, as can be seen in figure 2.

Each anode assembly 106 comprises an anode support 112, to be seen for example in figure 13, extending substantially parallel to a transverse direction Y of the electrolytic cell 100.

Electrolytic cell 100 here has four sides, two longitudinal sides 114 and two transversal sides 116 opposite each other in pairs, so that the electrolytic cell 100 can have a substantially rectangular shape.

Electrolytic cell 100 defines an opening 118 which is designed for insertion or extraction of the anode assemblies 106 respectively inside or outside the electrolytic cell 100.

It should be noticed that the opening 118 is adapted to allow the anode assemblies 106 to be inserted or extracted by substantially vertical movement, respectively downwards or upwards.

The confinement chamber 108 may be substantially rectangular and placed on the edges of the pot shell 102, as seen in figure 2.

The confinement chamber 108 forms a confinement volume inside which the anode assemblies 106 are designed to move during the electrolysis reaction, as the carbonaceous blocks of the anode assemblies 106 are consumed.

According to the embodiment of figures 1 to 11, electrolytic cell 100 also comprises a plurality of hoods 120.

The hoods 120 extend from one longitudinal side 114 of the electrolytic cell 100 to the other in order to close the opening 118.

Hoods 120 are removable to make it possible to form an access window 124 through the hood system. This access window 124 provides access to the interior of the electrolytic cell 100 for maintenance operations, for example to break or saw through the crust formed on the surface of the electrolytic bath during the electrolytic reaction or to replace an anode assembly.

Hoods 120 advantageously extend substantially horizontally.

Each hood 120 may extend integrally from one longitudinal side 114 of the electrolytic cell 100 to the other.

As can be seen in the figures, storage device 1 extends above the electrolytic cell 100.

As shown in figure 2, storage device 1 is arranged above the anode assemblies 106 in place within the pot shell. In other words, storage device 1 is arranged above the anode assemblies 106 in production.

More particularly, storage device 1 extends between the two longitudinal opposite sides 114 of the electrolytic cell and more specifically between two longitudinal opposite upper edges of the confinement chamber 108.

The storage device 1 rests on the opposite longitudinal upper edges of the confinement chamber 108. The opposite longitudinal top edges are advantageously formed for example by a sleeve for capturing gases from the cell (not shown).

This capture sleeve is part of a cell gas collection system that may equip the electrolytic cell 100. The system may include a manifold, to which cell gases are led through the capture sleeve, and the capture sleeve may have holes allowing air to communicate with the interior of the confinement chamber 108 to capture the cell gases.

According to the example of figures 1 to 11, storage device 1 is specifically placed above the hoods 120 of the electrolytic cell 100.

Although this is not shown, the fixed structure may include reinforcement means designed to allow the fixed structure to support the weight of storage device 1 and optionally of the load supported by storage device 1.

The load storage device 1 has support means on which the load to be stored above the electrolytic cell 100 is designed to rest on, and bearing means, designed to ensure that the support means rest stably above the electrolytic cell 100, especially above anode assemblies 106, opening 118, hoods 120 and confinement chamber 108.

The support means comprise one or more supporting surfaces 2 adapted to support a new anode assembly 106a, a spent anode assembly 106b and/or a device 122 for collecting crusts formed during an electrolytic reaction.

The load to be supported by the support means is therefore a new anode assembly 106a, a spent anode assembly 106b and/or a device 122 for collecting crusts formed during an electrolytic reaction.

The collection device 122 is designed to collect crusts formed by a covering material covering the electrolytic bath of the cell during the electrolysis reaction.

According to the embodiment of figures 1 to 11, the support surface(s) 2 is/are substantially planar.

According to the embodiment of figures 12 to 14, the support surface(s) 2 is/are curved.

It should be noted that the mass of an anode assembly 106 is of the order of ten to twelve tons. The mass of a crust collection device 122 can be as much as 3 to 4 tons. The support means and the bearing means to which are transmitted the weight of the support means and the load(s) must therefore be able to withstand these masses.

In addition, the support means and, where appropriate the bearing means must be able to withstand the temperatures and heat radiation above the electrolytic cell 100, without damaging their mechanical properties. In other words, the support means must be able to stably fulfill their support function of a load weighing several tons, despite the temperature above the electrolytic cell 100.

When one or more hoods 120 are removed to form an access window 124, the temperature one meter above the electrolytic cell 100 may be greater than 400°C or more because of the strong radiation from the electrolytic bath whose temperature is about 1000°C.

When hoods 120 are in place, i.e. when these hoods 120 close the opening 118, the temperature can be around 100°C. Preferably, the support means are positioned above hoods 120 which are in place, and offset with respect to hoods 120 which have been removed to change an anode assembly, so as to allow the hoods necessary for changing the anode assembly to be removed and so that the support means are only slightly subjected to radiation from the electrolytic bath.

The support means may comprise means for preventing the supported load from slipping or falling, such as peripheral flanges (not shown). The support surface(s) 2 may advantageously comprise a coating to increase adhesion between the support surface(s) 2 and the supported load.

The support means and I or the bearing means may further comprise anticorrosion means. For example, the anti-corrosion means have a special medium or coating designed to withstand attack from the electrolytic bath liquid that may flow from the spent anode assembly 106b and the temperature released by the spent anode assembly 106b. The support means may in particular include a containment box inside which the spent anode assembly is stored to contain the gases emitted by the spent anode assembly as it cools.

Storage device 1 comprises handling means to enable it to be handled by the moving means.

The moving means may include a handling machine or a handling crane (not shown), usually known as a pot tending machine.

The handling means may be advantageously shaped to permit raising of storage device 1. For example, the handling means comprise hooks (not shown) positioned on the periphery of storage device 1. This ensures the stability of the load once raised.

According to a the embodiment shown in figures 1 to 11, the support means are in the shape of a substantially flat plate 4, arranged to extend in a substantially horizontal plane.

Plate 4 has two opposite transverse edges 6. The bearing means extend preferably exclusively from the two transverse edges 6.

Plate 4 may have reinforcing means to limit its bending under the effect of the weight of a load. The reinforcing means include for example two flanges 8 extending along the longitudinal edges 10 of plate 4.

Plate 4 may be of substantially rectangular shape.

The bearing means include bearing surfaces and connecting components connecting the bearing surfaces and the support means. The connecting components may correspond for example to support legs, as shown in figure 1.

The connecting components 12 here extend substantially rectilinear and perpendicular to plate 4. Moreover, the connecting components 12 may include one end connected to an underside 14 of the support means, in particular the plate.

The support means have an underside 14 which may be provided with thermal insulation means, such as a coating of a thermally insulating material.

According the embodiment shown in figures 12 to 14, the support means comprise two concave housings 16, interdependent with the support means, and designed for an anode assembly 106 to hang from them. In particular, the housings 16 are designed to receive and support the anode support 112.

The bearing means comprise, in the example of figure 12 and 13, two opposite walls 18 from each of which protrudes one of the concave housings 16.

The concave housings 16 are facing each other.

Still according to the embodiment shown in figures 12 and 13, storage device 1 includes spacer means to make the two opposite walls 18 and the two concave housings 16 interdependent. The spacer means comprise for example walls or connecting arms 20 designed to extend in a transverse direction X of the electrolytic cell 100.

According to the example of figure 14, the bearing means may include two independent assemblies, i.e. which can be moved independently of one another, each comprising a bearing surface 22 on a structure fixed to the electrolytic cell 100, like the pot shell 102, and one or more support legs 24 connecting the bearing surface 22 to the support means. Both assemblies rest on two opposite sides of the electrolytic cell 100.

The invention also relates to a storage system comprising a plurality of separate and independent storage devices 1 having the above characteristics. The storage system is designed to store, above the electrolytic cell 100, a new anode assembly 106a, a spent anode assembly 106b and a device 122 used to collect the crusts formed during an electrolytic reaction.

This gives an advantageous spatial arrangement, insofar as two separate storage devices 1 can be placed on either side of the access window arranged to replace an anode assembly, as can be seen for example in figure 5.

Advantageously, the storage system includes three storage devices 1, including a first storage device 1a for supporting the new anode assembly 106a, a second storage device 1b for supporting the spent anode assembly 106b, and a third storage device 1c for supporting the crust collection device 122.

This allows a staggered or triangular arrangement of storage devices 1a, 1b, 1c as can be seen in figure 3, so that the period during which an access window is open in electrolytic cell 100 to perform an anode assembly change may be substantially reduced.

The storage system can be adapted to simultaneously support the new anode assembly, the spent anode assembly and the crust collection device. This limits the organizational constraints of a change of anode assembly.

The bearing means advantageously comprise bearing surfaces 22 designed to bear against a fixed structure of the electrolytic cell 100. In other words, the bearing surfaces 22 advantageously do not bear on the hoods 120. The bearing surfaces 22 are for example designed to rest on a substantially flat surface.

Electrolytic cell 100 has at least two counter-bearing surfaces (not shown), on which the bearing surfaces 22 are designed to rest. The two counter-bearing surfaces are arranged on either side of a longitudinal median plane of the electrolytic cell 100, i.e. a plane substantially perpendicular to the transverse direction Y of the electrolytic cell 100 and separating this cell into two similar halves.

The electrolytic cell can be equipped with the storage system described above.

The two counter-bearing surfaces are in particular arranged on either side of the opening 118.

The counter-bearing surfaces may preferably be a part of the upper belt of the pot shell 102 or a capture sleeve forming a belt in the top part of the confinement chamber 108.

The counter-bearing surfaces are preferably arranged on the longitudinal sides 114 of the electrolytic cell 100.

Although this is not shown, the bearing surfaces 22 and the counter-bearing surfaces may advantageously comprise interlocking means designed to work in conjunction by the complementarity of their shape. The interlocking means comprises for example pins designed to be inserted into the complementary shaped housings.

As can be seen for example in figure 2, the support means extend away from hoods 120.

The invention also relates to the electrolysis plant, especially an aluminum works, comprising a series of electrolytic cells, including electrolytic cell 100. The electrolysis plant according to the invention also comprises an operating aisle 1001 extending substantially parallel to the series of electrolytic cells, i.e. substantially perpendicular to electrolytic cell 100, and a storage device 1 described above.

The electrolytic cells are designed to have an electrolysis current of up to several hundred thousand amperes passing though them. The electrolytic cells may be arranged transversely to the direction of the line or series, i.e. substantially perpendicular to the overall direction of circulation of the electrolysis current across the line or the series.

The bearing surfaces 22 may optionally bear against a surface of an aisle 1002 between cells along a longitudinal edge of electrolytic cell 100 and separating electrolytic cell 100 from an adjacent electrolytic cell. In other words, the counter-bearing surfaces are located within the aisles between cells separating the longitudinal sides of two adjacent electrolytic cells in the series of electrolytic cells.

The bearing surfaces 22 may for example be supported on reinforced pavings or gratings in the aisle 1002 between cells.

The reason for resting the storage devices on surfaces of the aisles between cells instead of the fixed structure of the electrolytic cell is because the maneuver involved in putting them in place requires less precision and is therefore is simpler and quicker to perform. This helps to reduce the time taken to perform an operation, and therefore the time that electrolytic cell 100 is open.

Here too, the bearing surfaces 22 and counter-bearing surfaces may include interlocking means designed to work in conjunction by the complementarity of their shape, like those described above.

It should be noted that the support means advantageously define a space between them such that electrolytic cell 100 extends between the bearing means. In this way, each storage device 1 spans electrolytic cell 100, as shown in figure 1 or 3.

In particular, the bearing means, in particular connecting components 12, may be spaced apart by a distance greater than the width of electrolytic cell 100.

In addition, the bearing means, in particular connecting components 12, may extend over a height at least greater than the height of electrolytic cell 100.

The electrolysis plant further comprises moving means for moving storage device 1 above the electrolytic cell in a substantially longitudinal direction X of the electrolysis cell 100. The moving means comprise a handling machine for lifting the storage device 1.

The invention also relates to a method for changing a spent anode assembly 106b of an electrolytic cell, in particular electrolytic cell 100 described above, for a new anode assembly 106a.

This method comprises a step of setting up a storage device 1 as previously described, above the electrolytic cell, as can be seen in figure 4.

The set-up step includes positioning storage device 1 in line with one or more anode assemblies near to, and preferably adjacent to the spent anode assembly 106b, as shown in figure 2.

Storage device 1 is not positioned in line with the spent anode assembly used in order to allow hoods 120 to be moved so as to open an access window to allow this spent anode assembly to be extracted through the top, i.e. to be extracted by substantially vertical upward translation of the spent anode assembly and to enable the new anode assembly to be inserted from the top, i.e. a set-up by substantially vertical downward translation of the new anode assembly.

The method is implemented by means of a storage system comprising a plurality of separate storage devices 1, and the method comprises a step of positioning one of the storage devices 1 of the storage system above an electrolytic cell 101 adjacent to the electrolytic cell 100 comprising the spent anode assembly, as illustrated in figure 3. This storage device 1 is arranged opposite an access window 124 formed or shortly to be formed between hoods 120 so as to extract the spent anode assembly 106b and replace it with a new anode assembly 106a. This storage device 1 may therefore be arranged substantially symmetrically to access window 124 with respect to the aisle 1002 between cells separating the electrolytic cell 100 with the spent anode assembly from the electrolytic cell 101 above which the storage device 1 is positioned.

The anode assembly change is preferably carried out by means of a pot tending machine moving only between the transverse sides 116 of electrolytic cell 100 comprising the spent anode assembly and optionally an electrolytic cell 101 adjacent to electrolytic cell 100 comprising the spent anode assembly throughout the period during which the access window 124 is formed between the hoods 124.

The method may also include some or all of the following steps:

- a step involving withdrawal of one or more hoods 120 to allow an access window 124 to be formed through which the spent anode assembly 106b and the new anode assembly 106a are to be removed, for example by means of a pot tending machine,

- a step involving breaking or sawing through the crust formed on the surface of an electrolytic bath,

- a step involving removing the spent anode assembly 106b to place it on the second storage device 1b (figures 5 and 6),

- a step involving cleaning the crusts by means of a tool such as a crust shovel 130 (figure 7),

- a step involving collecting crusts by depositing these crusts in the collection device 122 positioned if necessary on the third storage device 1c,

- a step involving removal of the new anode assembly 106a of the first storage device 1a (figure 9) and a step involving placing the new anode assembly 106a inside the electrolytic cell 100 (figure 10),

- a step involving closing the access window 124 by repositioning the hood(s) 120 initially removed.

The three storage devices 1a, 1b, 1c can then be moved and positioned above another cell, for example an adjacent one as seen in figure 11.

Of course the invention is not in any way limited to the embodiment described above, this embodiment only being provided by way of example. Modifications are possible, in particular from the point of view of the constitution of the various components, or through replacement by technical equivalents, without thereby going beyond the scope of protection of the invention.

Claims (20)

1. Storage device for a load above an electrolytic cell comprising a pot shell, hoods, a cathode and anode assemblies arranged in the pot shell and covered by the hoods, the load storage device comprising support means on which the load to be stored above the electrolytic cell is designed to rest in a volume formed by vertical translation of a surface obtained by projecting the electrolytic cell in a horizontal plane, and bearing means designed so that the support means rest stably above the electrolytic cell, particularly above the anode assemblies and the hoods.

2. Storage device according to claim 1, wherein the support means comprise one or more supporting surfaces adapted to support a new anode assembly, a spent anode assembly and/or a device for collecting crusts formed during an electrolytic reaction.

3. Storage device according to claim 1 or 2, wherein the storage device comprises handling means to enable it to be handled by moving means.

4. Storage device according to any one of claims 1 to 3, wherein the support means are in the shape of a substantially flat plate, arranged to extend in a substantially horizontal plane.

5. Storage device according to claim 4, wherein the plate has reinforcing means to limit its bending under the effect of the weight of a load.

6. Storage device according to any one of claims 1 to 5, wherein the support means comprise two concave housings, interdependent with the support means, and designed for an anode assembly to hang from them.

7. Storage system including a plurality of separate and independent storage devices according to any one of claims 1 to 6, designed to store, above the electrolytic cell a new anode assembly, a spent anode assembly and a device used to collect the crusts formed during an electrolytic reaction.

8. Storage system according to claim 7, wherein the storage system includes three storage devices, including a first storage device for supporting the new anode assembly, a second storage device for supporting the spent anode assembly, and a third storage device for supporting the crust collection device.

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9. Electrolytic cell comprising a pot shell, hoods, a cathode and anode assemblies arranged inside the pot shell and covered by the hoods, and a storage device according to any one of claims 1 to 6, said storage device extending above the electrolytic cell.

10. Electrolytic cell and storage device according to claim 9, wherein the storage device is arranged above the anode assemblies in place inside the pot shell and hoods covering these anode assemblies.

11. Electrolytic cell and storage device according to claim 9 or 10, wherein the electrolytic cell comprises two opposite longitudinal sides and the storage device extends between the two opposite longitudinal sides of the electrolytic cell.

12. Electrolytic cell and storage device according to claim 11, wherein the electrolytic cell comprises at least two counter-bearing surfaces on which the bearing surfaces of the storage device are designed to rest, and the bearing surfaces and counter-bearing surfaces include interlocking means designed to work in conjunction by the complementarity of their shape.

13. Electrolysis plant, especially an aluminum works comprising a series of electrolytic cells, including one electrolytic cell and at least one storage device according to any one of claims 9 to 13, and an operating aisle extending substantially parallel to the series of electrolytic cells.

14. Electrolysis plant according to claim 13, wherein the support means comprise bearing surfaces intended to bear against a surface of an aisle between cells along a longitudinal edge of the electrolytic cell and separating said electrolytic cell from an adjacent electrolytic cell.

15. Electrolysis plant according to claim 13 or claim 14, wherein the support means define a space between them such that the electrolytic cell extends between the bearing means of the storage device.

16. Method for changing a spent anode assembly in an electrolytic cell for a new anode assembly, comprising a step of setting up a storage device according to any one of claims 1 to 6 above the electrolytic cell.

17. Method according to claim 16, wherein the setting-up step comprises positioning the storage device in line with one or more anode assemblies, close to, and preferably adjacent to the spent anode assembly.

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18. Method of claim 16 or claim 17, wherein the method is implemented by means of a storage system according to claim 7 or 8, and the method comprises a step of positioning one of the storage devices of the storage system above an electrolytic cell adjacent to the electrolytic cell comprising the spent anode assembly.

19. Method according to claim 18, wherein the method comprises steps consisting in making an access window between the hoods of the electrolytic cell to extract the spent anode assembly and replace it with a new anode assembly and arranging said storage device facing the access window.

20. Method according to any one of claims 16 to 19, wherein the method comprises a step of making an access window between the hoods of the electrolytic cell for extracting the spent anode assembly and replacing it with a new anode assembly and the method includes performing a change of anode assembly by means of a pot tending machine moving only between the transverse sides of the electrolytic cell comprising the spent anode assembly and optionally of an electrolytic cell adjacent to said electrolytic cell comprising the spent anode assembly throughout the period during which the access window is formed between the hoods of the electrolytic cell to extract the spent anode assembly and replace it with a new anode assembly.