AU2015226002B2

AU2015226002B2 - System for carrying out operations linked to the use of cells of a facility for producing aluminium by means of electrolysis

Info

Publication number: AU2015226002B2
Application number: AU2015226002A
Authority: AU
Inventors: Jerome Guerin
Original assignee: Fives ECL SAS
Current assignee: Fives ECL SAS
Priority date: 2014-03-05
Filing date: 2015-02-16
Publication date: 2019-04-04
Anticipated expiration: 2035-02-16
Also published as: CN106460209A; CA2938716C; FR3018283B1; AU2015226002A1; RU2016135644A3; WO2015132479A2; FR3018283A1; EP3114257A2; WO2015132479A3; CA2938716A1; CN106460209B; RU2016135644A; AR099617A1; EP3114257B1; RU2699600C2

Abstract

The system (50) is intended to be mounted on a mobile unit of the facility in order to be able to be moved over the cells. It comprises: a support (51) intended to be mounted on the unit; a hinged arm (52) mounted on the support; a gripping device (60) for gripping at least one cover (33) designed to be able to be coupled to a first end (53) of the arm; and a temporary storage device (55) for storing at least one cover, said storage device, mounted on the support, being capable of receiving at least one cover delivered by the arm provided with the gripping device and of allowing said arm provided with the gripping device to retrieve at least one cover previously placed in the storage device.

Description

SYSTEM FOR CONDUCTING OPERATIONS RELATED TO THE USE OF CELLS IN AN INSTALLATION FOR PRODUCING ALUMINUM BY ELECTROLYSIS

The present invention relates to a system for conducting operations related to the use of cells in an installation for producing aluminum by igneous electrolysis.

The invention also relates to a unit for operating the cells of such an installation, the unit comprising such a system, and an installation for producing aluminum by igneous electrolysis.

The invention also relates to a method for intervening on a cell of such an installation.

Aluminum is produced industrially by igneous electrolysis in electrolytic cells according to the well-known Hall-Heroult process. The French patent application FR 2 806 742 (corresponding to American patent US 6 409 894) describes the installations of an aluminum reduction plant intended for the production of aluminum.

The electrolytic reactions, the secondary reactions and the high operating temperatures result in the production of gaseous effluents which primarily contain carbon dioxide and fluorinated products. The release of these effluents into the atmosphere is strictly controlled and regulated, regarding not only the ambient atmosphere of the electrolysis hall, for reasons concerning the working conditions of personnel operating close to the cells, but also regarding atmospheric pollution. The pollution-control regulations of several countries impose limits on the amounts of effluents released into the atmosphere.

Solutions currently exist that allow for the reliable and successful extraction, recovery and processing of these effluents. A widespread solution consists in equipping the electrolytic cells with an effluent collection device. This device hoods the electrolysis vats and comprises containment means, which notably include a hood means, and suction and chemical effluent processing means.

The hood means comprises removable hoods that provide access inside the cell, particularly when replacing a spent anode with a new anode. Access to the inside of the cell may also be necessary during other interventions, such as the removal of the liquid metal, covering the bath or various maintenance operations.

According to a first known method, the hoods are removed from the cell and replaced manually, one by one, by a ground-based operator. The operator is then exposed to risks related to the proximity of the electrolytic cell and the presence of handling equipment. In particular, the position needed to pick-up and drop-off of the hoods requires the operator to lean towards the cell. As the hoods rest on narrow surfaces, incorrect positioning a hood could result in it being poorly seating on the cell, thereby destabilizing the operator

2015226002 12 Mar 2019 and causing him to fall into the pot. On the other hand, removing the hoods reduces the efficiency of the collection device and exposes the operator to effluents from the cell, which requires that protective masks be worn.

In a second known process, described in French Patent 2 879 582 (corresponding to US Patent No. 8 273 223) for example, the hoods are removed from the cell and replaced by a system that comprises:

- a support intended to be mounted on a movable unit of the installation so it can be moved above the cells;

- and a first articulated arm mounted on the support and equipped with a device for gripping at least one hood.

Before placing a hood on the cell, the surface of the cells on which the hood will bear must be cleaned. Bits of the hardened bath may have fallen on this surface while the anode was being replaced, and the presence of these pieces would prevent proper positioning of the hood. To carry out this cleaning operation, the system of document FR 2 879 582 comprises a second articulated arm mounted on the support and provided with a cleaning tool such as a brush. Thus, a hood in place on a cell is removed by the first arm equipped with the gripping device, then the second arm equipped with the cleaning tool performs the cleaning operation while the hood remains connected to the first arm, and then the first arm places the hood back on the cell.

Such a system is generally satisfactory. However, it presents a number of drawbacks. In particular, it has a relatively complex and bulky structure, which can have negative consequences on its implementation and maintenance. In addition, this system is relatively fixed in that it is difficult to adapt to different kinds of hoods and cells, and to develop it so that it can perform other operations the on cells.

It is an object of the present invention to substantially overcome, or at least ameliorate, one or more of the above drawbacks.

To this end, and according to a first aspect, the invention relates to a system for conducting operations associated with the operation of cells of an installation for producing aluminum by igneous electrolysis, including cell hood handling operations, the system being intended to be mounted on a movable unit of the installation so that it can be moved above the cells, the system comprising:

- a support intended to be mounted on the unit;

- an articulated arm mounted on the support;

- a gripping device of at least one hood designed to be coupled to a first end of the arm;

AH26(22299811_1):BJM

- and, in addition, a temporary storage device for at least one hood, said storage device, mounted on the support, being capable of receiving at least one hood conveyed by the arm equipped with the gripping device and fitted to allow said arm, equipped with the gripping device, to retrieve at least one hood previously placed in the storage device.

Owing to the presence of the storage device mounted on the support, the articulated arm is not required to permanently hold the hoods while the operations requiring the removal of the hoods (particularly the replacement of one or more anodes) and operations prior to putting the hoods back into place (particularly the cleaning of certain areas of the cell) are performed. Therefore, the articulated arm, free of the hoods, may be used to perform other operations, and then retrieve the hoods placed in the storage device in order to place them back on the cell.

Thus, insofar as this arm can perform various operations, the system can be more compact and less expensive to manufacture and maintain.

In particular, according to one possible embodiment, it may be considered that the system comprises a single articulated arm mounted on the support. The gain in compactness is thus increased even further.

This arm may be dedicated to hood handling operations and to the cleaning of areas of the cell whereon the hoods are placed. Additionally, it may be designed to perform other operations, thus increasing the versatility of the system with compactness remaining substantially unchanged.

Alternatively, provision may also be made so that the system includes an additional arm for operations other than the aforementioned hoods handling and cleaning, notably if these other operations require specific functionalities or a structure of the arm performing them.

According to one possible embodiment, the system further comprises a tool storage device, including at least the gripping device and a cleaning tool, the storage device, mounted on the support, being arranged to be able to receive at least one tool provided by the arm and for allowing said arm to take one of the tools placed in the storage device.

With this arrangement, the arm can only be fitted with the tool needed to perform the operation in progress, while the other tools are placed in the storage device during this time. In particular, cleaning can be performed by the arm not carrying the gripping device, making it more practical and efficient during the cleaning operation.

In addition, the presence of the storage device ensures system versatility in very good operating conditions. Indeed, the tools remain on the system and are not placed on the floor of the installation, for example, thereby saving floor space, the undesired movement of the tool and difficulty in locating it so the arm can retrieve it.

The support may comprise a base whereon the following are fixedly mounted: the arm, the temporarily storage device for at least one hood, and the tool storage device, when present. The arm and both storage devices are thus located in the same repository, so it is not necessary to provide a detection device so the arm can correctly take - or retrieve one or more hoods stored or a stored tool.

It can be provided that the first end of the arm is equipped with first coupling means and that the gripping device, or any other tool that can be coupled to the first end of the arm, is equipped with second coupling means designed to removably cooperate with the first coupling means. In particular, the second coupling means may be identical on all the tools so that a universal coupling system is obtained. The coupling holds the tool on the arm, from a mechanical perspective, but also from an electrical and/or pneumatic or hydraulic perspective for the transmission of energy and actuation commands.

Preferably, the second coupling means are accessible when the tool is located in the storage device, so that it can be approached by the first end of the arm and cooperate with the first coupling means.

The temporary storage device for at least one hood can be designed to receive a plurality of hoods arranged substantially in the same vertical plane, with their side edges substantially horizontal, the hoods being superimposed in a substantially contiguous manner in the vertical direction. This allows gravity to remove any play that could exist between the hoods before they are removed from the cell. Consequently, the overall size of the entire set of hoods is smaller than the space in which this set must be placed back into, which facilitates putting the hoods back into place.

In one possible embodiment, the temporary storage device for at least one hood comprises a movable member between an open position permitting the introduction or removal of at least one hood into/out of said storage device, and a closed position wherein the hood(s) are maintained in said storage device.

The system may further comprise a detection device capable of determining the precise position of a hood on a cell before it is gripped by the arm, and capable of detecting an element next to the cell location where a hood must be repositioned by the arm, in order to enable said hood to be properly repositioned. These two functions can be performed by the same detection device, or by two separate members of the detection device. For example, the detection device may include at least a telemetry system, such as a laser range finder.

The support may comprise at least one part that is movable substantially vertically in operation, and whereon the arm is mounted. This movable part - in relation to the unit on which the support is mounted - can typically be the base. The arm is, for example, fixed by its second end on the lower part of the support.

Thus, said movable part of the support can be raised so that the system, and the arm in particular, does not hinder the other operations that must be carried out on the cell and/or that it does not touch a part of the cell (positive riser, superstructure, etc.) when the unit must be moved.

According to a second aspect, the invention relates to a unit for the operation of cells of an installation for producing aluminum by igneous electrolysis, the unit comprising:

- a travelling crane comprising two beams extending transversely and which is designed to move in the longitudinal direction above the cells;

- a carriage mounted in a transversely-movable manner on the two beams of the travelling crane;

- and a system as described above, the support of the system being mounted on the carriage.

According to a third aspect, the invention relates to an installation for producing aluminum by igneous electrolysis, comprising:

- a building wherein a plurality of cells are located, each cell extending in a transverse direction, the cells being arranged beside one other in a longitudinal direction;

- a unit as described above, the travelling crane being mounted so as to be longitudinally movable on longitudinal rails provided in the vicinity of two transverse end walls of the building.

According to a fourth aspect, the invention relates to a method for intervening in a cell of an installation for producing aluminum by igneous electrolysis, comprising, in this order, the following steps:

a) take at least one hood present on a cell, using an articulated arm mounted on a support and equipped with a gripping device for at least one hood;

b) using said arm, place the hood(s) in a temporary storage device for at least one hood mounted on the support, then separate the gripping device and the hood(s) so as to free the arm;

c) by means of said arm, retrieve at least one hood previously placed in the storage device;

d) replace said hood(s) on the cell by means of said arm.

Thus, after step b), the arm is free of the hoods and can perform other operations.

The method may further comprise, between steps b) and c), and in this order, the following steps:

- using said arm, i.e. the arm that performs the hood handling operations a) to d), place the gripping device in a tool storage device mounted on the support;

- couple to said arm a tool, other than the gripping device, present in the storage device;

- perform an operation with said tool;

- replace said tool in the storage device;

- couple the gripping device back onto said arm.

Typically, said tool, other than the gripping device, can be a cleaning tool such as a brush, the operation performed by said tool thus being an operation to clean at least one area of the cell.

We now describe, as a non-limiting example, a possible embodiment of the invention, with reference to the appended figures:

Figure 1 is a schematic sectional view of an aluminum production installation employing fused bath electrolysis comprising a system according to the invention;

Figure 2 is a schematic sectional view of an electrolytic cell of the installation;

Figure 3 represents, in a perspective view, part of the cell of figure 2;

Figure 4 is a perspective view of the system according to an embodiment of the invention;

Figures 5 and 6 are views of a temporary storage unit for the cell hoods belonging to the system of figure 4, in a perspective and top view respectively, the storage device being empty;

Figures 7 and 8 are views similar to figure 5, the storage device receiving one and three hoods respectively;

Figures 9 to 16 illustrate successive steps of the intervention process on a cell according to the invention using the system depicted in figure 4.

Figure 1 represents an aluminum production installation 1 employing fused bath electrolysis, and more particularly an electrolysis hall of such an installation 1.

The installation 1 comprises a building 2 in which a plurality of electrolysis cells 3 are located. Each cell 3 extends in a transverse direction Y, and the cells 3 are arranged next to one another in a longitudinal direction X.

As illustrated in figures 2 and 3, each cell 3 comprises a pot 20, a support structure 30 referred to as the “superstructure” and a plurality of anodes 40, 40’.

The pot 20 comprises a steel shell 21, an internal lining 22 which is generally formed by blocks made of refractory materials, and a cathode assembly which comprises blocks made of a carbonaceous material, called “cathode blocks” 23, and metal connection bars 24 to which the electrical conductors 45, 46, 47 are attached, for conveying the electrolysis current.

Each anode 40 is equipped with a metal stem 41 which is typically attached to the anode 40 via a multipode 42. The anodes 40 are removably secured to a movable metal frame 25, called the “anode frame”, by means of a movable connector 26. The anode frame 25 is supported by the superstructure 30 and fastened to electrical conductors 47, called “positive risers”, used to convey the electrolysis current.

Generally speaking, more than a hundred cells 3 are arranged next to one another, in rows or lines, in the X direction. The cells 3 of a row are electrically connected in series using connecting conductors 45, 46, 47. The cells 3 are arranged to leave a circulation aisle 48 along the installation 1 and an access 49 between the cells 3.

Each cell 3 is equipped with a hood system. The system comprises a series of removable hoods 33 that are typically made of metal, and more typically made of aluminum alloy. The hood system confines effluents inside 29 the cell 3 and is connected to means (not shown) for discharging the effluents and directing them to a processing center.

The hoods 33 are typically inserted into a guide groove 35 arranged along the cell 3 (in the Y direction) and are brought to bear on a flange 31 of the superstructure 30. The hoods 33 are placed side by side on a cell 3, in the Y direction. There may be clearance between the side edges 36 of two adjacent hoods 33, in the order of approximately 2 to 5 mm. On the other hand, the hoods can be positioned with an angular defect of a few degrees around the X and Y axes. For example, the dimensions of a hood 33 can be as follows: width (along Y) of 685 mm and height of 1535 mm. The hoods 33 may be substantially planar or curved. The hoods 33 are held in position under their own weight, without a locking device. For example, the weight of a hood 33 may be in the order of 12 kg. The hoods 33 are generally equipped with a handle 34 for handling by operators.

The stem 41 of the anodes 40 typically emerges from the hood system through openings arranged for this purpose in the hood system.

According to the most common technology, the anodes 40 are made of prebaked carbonaceous material. The progressive consumption of the anodes 40 during electrolytic reduction reactions of the aluminum requires that work be performed on the cells 3, which includes, in particular, the replacement of spent anodes 40' with new anodes 40.

The installation 1 comprises a unit 4, so-called “pot tending assembly”, for the operation of the cells 3, i.e. to conduct operations on the cells 3 such as anode replacements or the crushed bath and AIF₃ feed hoppers of the cells 3. Unit 4 can be also used to handle various loads, such as pot elements, ladles of molten metal or anodes.

As illustrated in figure 1, the unit 4 comprises a travelling crane 5 which features two beams 6 extending transversely and which is adapted to move in the longitudinal direction X above the cells 3. More specifically, the travelling crane 5 is mounted so as to be longitudinally movable on longitudinal rails 7 or tracks which may be provided in the vicinity of two transverse end walls 8 of the building 2.

The unit 4 further comprises a carriage 9 mounted so as to be transversely mobile on the two beams 6 of the travelling crane 5. The carriage 9 is part of a pot tending machine 10 that also includes a pot tending module 11 equipped with a plurality of handling and servicing devices 12. The pot tending machine 10 may also include a control cab.

On the pot tending machines 10 used for anode replacement operations, these handling and servicing devices 12 include tools, namely typically a crust breaker, a bucket shovel, an anode gripping device (called “anode clamp”) and a hopper equipped with a retractable duct. The crust breaker is used to break the crust of alumina and solidified bath which generally hoods all or part of the anodes 40 of the cell 3; the bucket shovel is used to clear the location of the anode 40, once the used anode has been withdrawn, by removing the solid matter located there (such as pieces of crust and alumina); the anode clamp is used to grip and manipulate the anodes 40 by their stem 41, particularly removing spent anodes from a cell 3 and placing new anodes 40 in the cell 3; the retractable duct is used to introduce alumina and/or crushed bath into the cell 3, so as to form a coating layer, after a new anode has been put into place. The crust breaker, the bucket shovel and the anode clamp are typically mounted to the lower end of a guide member such as a mast or a telescopic arm.

In addition, the unit 4 includes a system 50 for conducting operations related to the operation of the cells 3 of the installation 1, particularly operations for handling the hoods of the cells 3 and for cleaning at least one area of the cell 3.

As illustrated in figure 4, the system 50 comprises a support 51 which is mounted on the unit 4, and more precisely on the carriage 9, so that it can be moved above the cells 3. The system 50 further comprises an articulated arm 52 mounted on the support 51. For example, the arm 52 comprises a first free end 53 and a second end 54 attached on the lower part of the support 51. It may be a six-axis anthropomorphic robot. The arm 52 may be the sole articulated arm mounted on the support 51.

Generally speaking, the support 51 may be designed so that the arm 52 can be moved substantially vertically while in operation. This allows the arm 52 to be brought near a cell 3 when an operation must be conducted on the cell 3, and to maintain the arm 52 in a raised position the rest of the time so that it does not interfere with other servicing operations, or so that any movement of the unit 4 carrying the system 50 is not hindered by the fact that the arm 52 may come into contact with part of the cell 3, such as a positive riser 47 or the support structure 30. For this purpose, it can be provided that the support 51 comprises a telescopic mast in a substantially vertical direction Z.

The system 50 further comprises a temporary storage device 55 for at least one hood 33, mounted on the support 51 and, in the embodiment shown, a tool storage device 56 also mounted on the support 51.

In the embodiment shown in figure 4, the support 51 comprises a base 57 on which the following are fixedly mounted: the arm 52, the temporary storage device 55 for at least one hood, and the tool storage device 56. More specifically, the base 57 can be mounted on the lower part of the support 51 and be vertically movable in relation to the upper portion of the support 51, this vertical movement being actuated by a jack 58. In addition, the base 57 may include a wing 65 on which the storage device 55 is mounted and a wing 66 on which the tool storage device 56 is mounted.

Various tools that can be manipulated by the arm 52, can be found in the tool storage device 56, and in particular:

- a gripping device 60 for at least one hood 33, for example comprising a body provided with branches bearing gripping devices 59 such as suction cups, activated by a pneumatic system for example;

- and a cleaning tool 63, such as a brush, a scraper or a blowing means.

The tool storage device 56 is arranged so as to be able to receive at least one tool 60, 63 provided by the arm 52 and so as to allow said arm 52 to take one of the tools 60, 63 placed in the storage device 56. Besides the gripping device 60 and the cleaning tool 63, the storage device 56 may receive, for example, a gauging sensor, measuring tools, brushing tools for other parts of the cell (anode frame, anode rods), bath removal tools, etc.

To this end, the first end 53 of the arm 52 may be equipped with first coupling means 61, while each of the tools likely to be coupled to the first end 53 of the arm 52, particularly the gripping device 60 and cleaning tool 63, may be equipped with a second coupling means 62 designed to removably cooperate with the first coupling means 61. In an advantageous version of the invention, the second coupling means 62 are identical for all of said tools, thereby creating a universal coupling system.

The coupling means 61, 62 are designed to provide a releasable connection between the first end 53 of the arm 52 and the tools, particularly the gripping device 60 and the cleaning tool 63, and to ensure automatic connection of pneumatic and electrical power supplies between the arm 52 and tools. In the case of a universal coupling system, the coupling means 61, 62 should preferably have sufficient connections for each tool to be connected to the arm 52. In addition, the coupling means 61, 62 are preferably designed to guarantee that the tools are held in place in the event of a power failure.

The function of the tool storage device 56 is to allow tools that are not being used at a given time to be stored. These unused tools are preferably locked on the storage device 56, by means of jacks for example. The storage device 56 may comprise several elements 64 integral with the wing 66 connected to the base 57, each of these elements 64 serving as a base on which an unused tool can be placed or locked.

The temporary storage device 55 for at least one hood is designed to receive at least one hood 33 carried by the arm 52 equipped with the gripping device 60, and to allow said arm 52 equipped with the gripping device 60 to retrieve at least one hood 33 previously placed in the storage device 55.

The storage device 55 will now be described more specifically with reference to figures 5 to 8.

In the embodiment shown, the storage device 55 comprises a substantially horizontal base 70, a first lateral upright 71 and a second lateral upright 73, substantially vertical and fixed relative to the base 70. The first and second lateral upright 71, 73 can be connected by the wing 65 connecting the storage device 55 to the base 57 of the support 51.

Furthermore, a substantially vertical shutter 72 is provided in the vicinity of the second lateral upright 73. The shutter 72 is movable relative to the second lateral upright 73 between an open position permitting the placement or removal of at least one hood 33 into/from said storage device 55, and a closed position in which the hood(s) 33 are/is kept in said storage device 55, in the storage position. In a non-illustrated variant, provision may also be made for a movable shutter in the vicinity of the first lateral upright 71.

The storage device 55 is preferably devoid of a front panel to allow the introduction, from the front, of one or more hoods 33, as well as their removal, by the arm 52. Moreover, the storage device 55 may be devoid of an upper cross member: in other words, it is open at the top. In addition, the storage device 55 may be devoid of a solid rear panel, the wing 65 forming the sole element at the rear of the storage device 55.

The shutter 72 may be placed away from or brought closer to the second lateral upright 73, so that one or more hoods 33 can be trapped between the second lateral upright 73 and the shutter 72, more specifically the free end of the shutter 72. In this storage position, the hoods 33 are thus held between the two uprights 71, 73 by means of the shutter 72.

Thus, when the shutter 72 is in a position away from the second upright 73, i.e. when it is in the open position (figures 5 to 8), it is possible to place or remove at least one hood 33 into/from the storage device 55. Conversely, when the shutter 72 is brought into a position closer to the second upright 73, i.e. when it is in the closed position (figure 4), the hood(s) 33 is/are held in the storage device 55.

In the embodiment shown, the storage device 55 comprises an actuating member designed to be able to move the movable member - namely the shutter 72 - between its open and closed positions. As illustrated in figure 6, this actuating member is in the form of at least one jack 75, for example. The jack 75 may be connected to a lug 76 integral with the shutter 72 and articulated around a substantially vertical axis 77 and fixed relative to the second upright 73. Thus, the movement of the shutter 72 between its open and closed positions involves a rotation of the shutter 72 about the axis 77. A limit switch can also be provided on the jack 75.

In addition, the first upright 71 - and possibly the second upright 73 and/or the shutter 72 may have a substantially vertical groove 74 open toward the second upright 73 - or more generally the opposite upright - wherein one edge of at least one hood 33 is intended to fit. Typically, the one or more grooves 74 receive an upper and/or lower edge of the hood 33, the terms “upper” and “lower” referring to the position occupied by a hood 33 on a cell 3. In practice, this upright 71 may have a V-shaped cross section, as shown in figure 6. This arrangement improves the positioning and retention quality of the hoods 33 in the storage device 55.

When only one hood 33 is in the storage position in the storage device 55, it rests on the base 70 and is held between the two uprights 71, 73, owing to the shutter 72, as illustrated in figure 7, its side edges 36 being substantially horizontal.

When several hoods 33 (up to three in the embodiment illustrated in figure 8) are in the storage position in the storage device 55, the lower hood 33 rests on the base 70. Furthermore, the hoods 33 are arranged substantially in the same vertical plane and superimposed substantially contiguously along the vertical direction Z. In addition, when placed on a cell 3, the hoods 33 have side edges 36 which are located substantially in a plane (X, Z), as shown in figure 3. In contrast, in the storage position, as shown in figures 7 and 8, the hoods 33 have their side edges 36 substantially horizontal, i.e. they have been turned 90° in relation to the position that they occupy when placed on a cell 3.

In addition, the system 50 may comprise means to detect the presence of at least one hood 33 in the storage device 55. As seen in figure 5 in particular, these detection means may comprise one or more fingers 78 arranged on the base 70 of the storage device 55, these fingers 78 projecting upwards and being pressed under the weight of one or more hoods 33 placed in the storage device 55.

The temporary storage device 55 for at least one hood 33 is preferably secured, i.e. designed to ensure that the hoods 33 are held in place even in the event of a power failure, preventing them from accidentally falling.

The arm 52 can be equipped with a cable support chain 80 (see notably figure 9) wherein will be installed all cables and hoses required to operate the system 50. In addition, the system 50 comprises one or more boxes 79 containing various computer and/or pneumatic control systems, notably for controlling the locking system of the hoods 33 in the storage device 55 (by moving the shutter 72 to its closed position and maintaining it in this position) and the locking of the tools 60, 63 in the tool storage device 56. The systems housed in the box 79 may also allow communication with the programmed logic controller of the pot tending machine 10 for the acquisition of the commands and the relaying of information.

In reference to figures 9 to 16 which illustrate successive steps of a method for intervening on a cell 3 of the installation 1 requiring the removal then the reinstallation of hoods 33 of the cell 3. In particular, when replacing a spent anode 40' with a new anode 40, the hoods 33 located in front of the spent anode 40' must be removed, and then replaced once the new anode 40 is secured.

As shown in figure 9, the support 51 carried by the unit 4 is moved close to the cell 3 on which the intervention must take place, by means of the travelling crane 5 and the carriage 9. The arm 52 is then moved downward by means of the jack 58 of the telescopic support 51 in the embodiment shown, until the first end 53 of the arm 52 is located near the hoods 33 to be removed. The gripping device 60 is coupled to this first end 53. The tool storage device 56 contains at least the cleaning tool 63 in the queue.

The arm 52, equipped with the gripping device 60, takes at least one hood 33 present on a cell 3, as shown in figure 10. More specifically, the gripping device 60 may be designed to simultaneously take three hoods, or two hoods and a half hood (the half hoods can be arranged, for example, at the transverse ends of the cells 3). Generally speaking, three or four gripping devices 59 may be provided per hood 33.

To do this, the system may include a sensing device capable of determining the precise position of a hood 33 on a cell 3 before it is gripped by the arm 52. Indeed, as indicated above, the hoods 33 may be positioned with a variable clearance between them and/or with an angular defect of a few degrees around the X and Y axes. Detecting the actual position of the hood 33 ensures excellent positioning of the gripping members 59 on the hood 33 and therefore safe gripping, without risk of falling.

The precise position of a hood 33 can be determined, for example, by detecting the handle 34 of the hood 33 by means of the detection device.

The arm 52 carrying the hoods 33 via the gripping device 60 then places all of these hoods 33 in the storage device 55, as illustrated in figure 11. For this purpose, the hoods 33 - here three in number, this being just one example - are rotated 90° with respect to their position on a cell 3, the side edges 36 thus being substantially horizontal, and are placed by the arm 52 in the storage device 55 through its open front portion.

The hoods 33 are placed in the storage device 55 between the two uprights 71, 73, the shutter 72 being in the open position to enable the hoods 33 (Figure 11) to be introduced.

The shutter 72 is then moved to its closed position so that the hoods 33 are maintained between the uprights 71, 73 and the shutter 72 (figure 12). The gripping device 60 may then be disconnected from the hoods 33 without the risk of them falling.

Once the hoods 33 have been removed from the cell 3, the pot tending machine 10 may intervene on the cell 3 to perform various operations, particularly, but not exclusively, to replace the anode. During these interventions, the hoods 33 are held in the retracted position, and therefore do not hinder these interventions. More generally, the arms 52 and the entire system 50 are positioned so as not to hinder these interventions. Concretely, the system 50 can be raised (by means of the telescopic support 51 in the embodiment described), and it will later be lowered when will again need to be used to perform other operations.

The arm 52, not having to maintain the hoods 33, can be used to perform other operations, generally by means of other tools. Thus, initially, the arm 52 is released from the gripping device 60 by placing it in the storage device 56, typically on the corresponding member 64.

The arm 52 then connects to a tool - other than the gripping device 60 - present in the storage device 56 through cooperation between the first coupling means 61 provided at the first end 53 of the arm 52 and the second coupling means 62 provided on the tool. The arm 52 can then use this tool to perform an operation associated with the operation of the cell 3, but other than handling the hoods 33.

In the embodiment shown in figure 13, this tool is the cleaning tool 63, which is used to clean at least one area of the cell 3, as shown in figure 14.

Concretely, after an anode has been replaced, and before the hoods 33 are put back into place on the cell 3, the guide groove 35 must be cleaned, along the entire length uncovered when the hoods 33 are removed, in order to remove all pieces - i.e. the hard bath and crushed bath debris - that could have fallen during the anode 40 replacement operation. To clean the guide groove 35, the cleaning tool 63 can typically place these pieces inside the pot 20. The arm 52 should preferably be designed to allow for cleaning under the right and left positive risers 47 without turning back.

Once the cleaning operation is completed, the cleaning tool 63 may be put back into the storage device 56, on the corresponding element 64, and then the arm 52 can be disconnected from the cleaning tool 63.

The arm 52 can then be connected to another tool present in the storage device 56 in order to perform another operation.

As illustrated in figure 15, the arm 52 can retrieve the gripping device 60 which it has previously placed in the temporary storage device 56, by cooperation between the first coupling means 61 provided at the first end 53 of the arm 52 and the second coupling means 62 provided on the gripping device 60.

The arm 52, equipped with the gripping device 60 in this manner, may then retrieve one or more hoods 33 previously placed in the storage device 55. This operation does not require a device able to detect the precise position of the hoods 33 hoods since they have remained in the same reference position as the arm 52 since their placement in the storage device 55. This saves time and enhances reliability.

Once the gripping members 59 are suitably associated with the hoods 33, the shutter 72 of the storage device 55 may be moved to its open position to allow the hoods 33 to be removed from the storage device 55.

Then, as illustrated in figure 16, the arm 52 is moved so that it can replace the hood(s) 33 that it holds on the cell 3. In order to enable appropriate repositioning of the hoods 33, the system 50 may comprise a detection device able to detect an element neighboring the location of the cell 3 where the hoods 33 must be repositioned by the arm 52. This neighboring element may, for example, be an adjacent hood 33 already in place on the cell 3 or, in the case where the hoods to be repositioned are hoods located on a transverse end of the cell 3, an end wall of the cell 3.

The arm 52 inserts the hoods 33 into the guide groove 35 which has been previously cleaned, and places them on the edge 31 of the superstructure 30.

Insofar as the hoods 33 have been stored in a superimposed manner in Z, with their side edges 36 substantially horizontal, any play that may exist between two adjacent hoods 33, prior to removal from the cell 3, was corrected by gravity. Thus, the overall size - along Y of all the hoods 33 to be placed back on the cell 3 is smaller than the overall dimensions of this set of hoods 33 prior to their removal from the cell 3. In other words, the available location on the cell 3 to replace the hoods 33 is larger than the dimension along Y of this set of hoods 33. The replacement of the hoods 33 on the cell is greatly facilitated.

The process just described can be carried out automatically, the system 50 operating independently after the pot tending machine 10 positioned above the cell 3 has issued a cycle launch instruction.

Alternatively, particularly for making adjustments, manual operation may be considered, with operation performed by an operator acting on the controls present in the cab of the pot tending machine 10.

Thus, the system according to the invention enables hoods to be handled and to other operations (cleaning, etc.) to be performed in the very crowded environment of electrolytic cells, and with the required precision.

Owing to its modularity, the cycle time of the system can be considerably reduced, for example less than 100 seconds (taking of the hoods, cleaning and replacement of the hoods)..

As it is compact, the system can perform certain operations as a background task, insofar as they do not create a risk of collision with an element of the pot tending machine. This is particularly the case for the tool change between the gripping device and the cleaning tool, which can be done while the pot tending machine 10 intervenes on the cell 3 to break the crust of the bath, remove a spent anode or replace a new anode.

In addition to the financial impact, reducing the cycle time is advantageous in terms of safety and the environment, as the time during which the hoods are removed from the cells is reduced.

It goes without saying that the invention is not limited to the embodiment described above 5 by way of example, but comprises all technical equivalents and variants of the means described and their combinations.

Claims

1. A system for conducting operations associated with the operation of cells of an installation for producing aluminum by igneous electrolysis, including cell hood handling operations, the system being intended to be mounted on a movable unit of the installation so that it can be moved above the cells, the system comprising:

- a support intended to be mounted on the unit;

- an articulated arm mounted on the support;

- a gripping device of at least one hood designed to be coupled to a first end of the arm; wherein the system further comprises a temporary storage device for at least one hood, said storage device, mounted on the support, being capable of receiving at least one hood conveyed by the arm equipped with the gripping device and fitted to allow said arm, equipped with the gripping device, to retrieve at least one hood previously placed in the storage device.

2. The system according to claim 1, wherein it comprises a single articulated arm mounted on the support.

3. The system according to claim 1 or 2, wherein it further comprises a tool storage device for storing tools, including at least the gripping device and a cleaning tool, the storage device, mounted on the support, being arranged to be able to receive at least one tool provided by the arm and for allowing said arm to take one of the tools placed in the storage device.

4. The system according to any one of claims 1 to 3, wherein the support comprises a base whereon the following are fixedly mounted: the arm, the temporary storage device for at least one hood, and the tool storage device, when present.

5. The system according to any one of claims 1 to 4, wherein the first end of the arm is equipped with first coupling means and wherein the gripping device, or any other tool that can be coupled to the first end of the arm, is equipped with second coupling means designed to removably cooperate with the first coupling means.

6. The system according to any one of claims 1 to 5, wherein the temporary storage device for at least one hood is designed to receive a plurality of hoods arranged substantially in the same vertical plane, with their side edges substantially horizontal, the hoods being superimposed in a substantially contiguous manner in the vertical direction.

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2015226002 12 Mar 2019

7. The system according to any one of claims 1 to 6, wherein the temporary storage device for at least one hood comprises a movable member between an open position permitting the introduction or removal of at least one hood into/out of said storage device, and a closed position wherein the hood(s) are maintained in said storage device.

8. The system according to claim 7, wherein the storage device comprises an actuating member designed to be able to move the movable member between its open and closed positions.

9. The system according to any one of claims 1 to 8, wherein the storage device comprises a substantially horizontal base, a first and second lateral upright substantially vertical and fixed relative to the base, and, in the vicinity of at least one of the two lateral uprights, a substantially vertical shutter movable relative to said side upright between an open position permitting the introduction or withdrawal of at least one hood into/from said storage device, and a closed position in which the hood(s) is/are held in said storage device, in the storage position.

10. The system according to claim 9, wherein at least one of said uprights has a groove, substantially vertical and open towards the other upright, wherein one edge of at least one hood is intended to fit.

11. The system according to any one of claims 1 to 10, wherein it comprises means to detect the presence of at least one hood in the storage device.

12. The system according to any one of claims 1 to 11, wherein it comprises a detection device capable of determining the precise position of a hood on a cell before it is gripped by the arm, and capable of detecting an element next to the location of the cell where a hood is to be repositioned by the arm, in order to enable said hood to be properly repositioned.

13. The system according to any one of claims 1 to 12, wherein the support comprises at least one part that is movable substantially vertically in operation, and on which the arm is mounted; the arm being, for example, fixed at the lower part of the support by its second end.

14. System according to one of claims 1 to 13, wherein the support comprises a telescopic mast in a substantially vertical direction.

AH26(22299811_1):BJM

2015226002 12 Mar 2019

15. The system according to any one of claims 1 to 14, wherein the articulated arm is a six-axis anthropomorphic robot.

16. A unit for the operation of cells of an installation for producing aluminum by igneous electrolysis, the unit comprising:

wherein it further comprises a system according to any one of claims 1 to 15, the support of the system being mounted on the carriage.

17. An installation for producing aluminum by igneous electrolysis, comprising:

- a unit according to claim 16, the travelling crane being mounted so as to be longitudinally movable on longitudinal rails provided in the vicinity of two transverse end walls of the building.

18. A method for intervening on a cell of an installation for producing aluminum by igneous electrolysis, comprising, in this order, the following steps:

b) by means of said arm, place the hood(s) in a temporary storage device for at least one hood mounted on the support, then separate the gripping device and the hood(s) so as to free the arm;

c) using said arms, retrieve at least one hood previously placed in the storage device;

d) replace said hood(s) on the cell by means of said arm.

19. The method according to claim 18, wherein it further comprises, between steps b) and c), and in this order, the following steps:

- using said arm, place the gripping device in a tool storage device mounted on the support;

- couple to said arm a tool, other than the gripping device present in the storage device;

- perform an operation with said tool;

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2015226002 12 Mar 2019

- replace said tool in the storage device;

- couple the gripping device back onto said arm.

20. The method according to claim 19, wherein said tool, other than the gripping device, is a cleaning tool, and wherein the operation conducted with said tool is a cleaning operation of at least one zone of the cell.