EP1828438A2

EP1828438A2 - Handling device for hoods of a cell for electrolytic aluminium production

Info

Publication number: EP1828438A2
Application number: EP05850542A
Authority: EP
Inventors: Alain Van Acker; Ludovic Demeulenaere
Original assignee: ECL SAS
Current assignee: Fives ECL SAS
Priority date: 2004-12-21
Filing date: 2005-12-20
Publication date: 2007-09-05
Also published as: US20090238665A1; CN101103142B; WO2006067324A2; UA86287C2; BRPI0515865A; WO2006067324A3; US8273223B2; CA2591495A1; AR054717A1; MY144923A; RU2382834C2; RU2007127715A; ZA200704923B; FR2879582B1; CA2591495C; FR2879582A1; CN101103142A; NO20073152L

Abstract

The invention relates to a device (100) for handling the hoods (33) of a cell for producing aluminium by fused bath electrolysis comprising a positioning device (110) and a hood gripping system (160). Said positioning device (110) comprises a vertically guiding member (101), a movable support (120) which is mounted on said guiding member (101) in such a way that it is displaceable at least in a vertical direction by using a hinged arm (130), a first sub-frame (140) which is mounted on the hinged arm (130) in such a way that it is pivotable around a first axis of rotation (A) which is substantially horizontal in operation, wherein said hinged arm (130) is at least remotable from and closable to the first sub-frame (140) of the movable support (120), a motor (141) for pivoting the first sub-frame (140) about said first axis of rotation (A), a second sub-frame (150) mounted on the first sub-frame (140) in such a way that it is displaceable along a first pre-determined translation axis (B) which is substantially horizontal in operation and means for moving the second sub-frame (150) along said first translation axis (B). The hood gripping system (160) is fixed to the second sub-frame (150) and comprises a predetermined arrangement of gripping members (161) for catching a predetermined arrangement of hoods (33) at a predetermined number of fixing points. Said invention makes it possible to carry out an accurate and automated hood handling.

Description

DEVICE FOR HANDLING THE HOODS OF A CELL FOR THE PRODUCTION OF ALUMINUM BY ELECTROLYSIS

Field of the invention

The invention relates to the production of aluminum by igneous electrolysis according to the Hall-Héroult method. It relates more particularly to interventions on electrolysis cells, such as anode changes, and service units intended to perform these interventions.

State of the art

Aluminum is produced industrially by igneous electrolysis in electrolysis cells according to the well-known Hall-Héroult process. French patent application FR 2 806 742 (corresponding to US Pat. No. 6,409,894) describes the installations of an electrolysis plant intended for the production of aluminum. The electrolysis cells have a generally rectangular ground shape. Subsequently, we will denote by X the direction of the long side of a cell, Y the direction of the short side and Z the vertical direction.

Electrolysis reactions, side reactions and high operating temperatures result in the production of gaseous effluents, which mainly contain carbon dioxide and fluorinated products. The discharge of these effluents into the atmosphere is strictly controlled and regulated, not only with regard to the ambient atmosphere of the electrolysis room, for reasons of working conditions of the personnel operating near the cells, but also regarding air pollution. Several states' pollution regulations impose limits on the amount of effluent released to the atmosphere. Today, there are solutions that make it possible to extract, recover and treat these effluents reliably and satisfactorily. A widely used solution consists in providing the electrolysis cells with an effluent collection device. This device covers the electrolysis tanks and comprises means of containment, which include in particular a rollover device, and means for suctioning and chemical treatment of the effluents.

The rollover device comprises removable covers that allow access to the interior of the cell, especially when replacing a worn anode with a new anode.

The covers are removed from the cell and replaced manually, one by one, by a ground operator. The operator is then exposed to risks related to the proximity of the electrolysis cell and the presence of handling tools. In particular, the position of taking and removing the covers forces the operator to lean towards the cell. As the covers are based on reduced surfaces, the incorrect positioning of a cover can lead to a bad support of it on the cell, unbalance the operator and risk falling into the tank. On the other hand, the removal of the hoods reduces the efficiency of the collection device and exposes the operator to the effluents of the cell, which requires him to wear protective masks.

The plaintiff has therefore sought a procedure and means to avoid these disadvantages.

Description of the invention

The subject of the invention is a device for handling the covers of an igneous electrolysis aluminum production cell, which makes it possible to remove, move and replace covers that are remote from the cell and which is capable of be automated in whole or in part. The device for handling the covers of an electrolysis cell according to the invention comprises a positioning device capable of decomposing the handling operations of the covers into a determined set of basic movements and a gripping system of the hoods capable of grasping firmly a determined set of hoods.

In a preferred embodiment of the invention, the device for handling the covers is characterized in that it comprises:

a positioning device which comprises a vertical guide member, such as a telescopic mast, a movable support, such as a carriage, mounted on the vertical guide member so that it can be moved at least in a vertical direction in use, an articulated arm mounted on the mobile support, a first frame mounted on the articulated arm so as to be pivotable about a first substantially horizontal axis of rotation A in use, said articulated arm being at least able to move away and to bringing the first frame of the mobile support, a motor for pivoting the first frame about said first axis of rotation A, a second frame mounted on the first frame so as to be movable along a first translation axis B determined, which is substantially horizontal in use, and means for moving the second frame along said first translation axis B;

- A gripping system of the covers attached to the second frame and comprising a determined set of gripping members for gripping a determined set of covers in a fixed number of attachment points.

According to the invention, the handling operations of the covers are decomposed into a determined set of basic movements, each of these basic movements being provided by specific components of the device. The vertical guide member and the movable support serve mainly for the vertical movements of the gripping system, the articulated arm serves for the approach and the removal movements of the gripping system, the first frame and the motor associated with it are used for movements of orientation of the gripping system relative to the vertical, and the second frame and the means of displacement which are The partners are used for the lateral movements of the gripping system, that is to say the parallel movements at the long sides of the electrolysis cells. These movements can be enslaved.

The gripping of the hoods by the gripping system in a determined number of points reduces the uncontrolled mechanical oscillations of the hoods during handling and thus keeps the hoods in a fixed position determined relative to the second frame (this position being typically parallel to said frame ).

The device of the invention makes it possible to correctly handle the covers in the highly congested environment of the electrolysis cells, with the precision necessary for the mechanization and the possible automation of the handling operations.

The invention also relates to a service machine of a series of igneous electrolysis aluminum production cells comprising a plurality of covers, which is characterized in that it comprises at least one cap handling device according to the invention. 'invention. A service machine is used to perform various operations on the electrolysis cells, in particular the anode changes. It is equipped with specialized tools for these various operations, generally mounted on substantially vertical arms, preferably telescopic arms, which move said tools between their working area and a rest position located at a safe altitude. Advantageously, said cap handling device is fixed to said service machine by means of the vertical guide member, which can thus play a role identical to that of the telescopic arms of adjacent tools.

The invention also relates to a mobile unit, capable of moving in the electrolysis room, comprising at least one cap handling device according to the invention. Advantageously, this mobile unit is provided with a control system ensuring that said positioning device is in a position determined with respect to the hood or to the plurality of covers to be handled. Said mobile unit is used to move the handling device towards and away from a hood or set of hoods determined, aiming at a determined position that can be defined by a distance ΔX along the X direction of the long side of the electrolysis cell, a distance ΔY along the Y direction of the short side of the electrolysis cell and a altitude difference ΔZ between a characteristic point of the handling device, for example a particular point of the mobile support, and a characteristic point of the plurality of covers to be handled, for example the position of the anode rod for the replacement of which it is necessary to remove said plurality of covers. Said predetermined position represents the initial position of the positioning device before it is put into action, and constitutes a point of reference for the subsequent movements imposed on the various elements that make up said handling device.

Said mobile unit may be a self-propelled vehicle capable of moving in the electrolysis room. It may also be a service unit comprising a movable bridge, typically capable of moving in alignment with the cells, a carriage, typically able to move along said movable bridge and a service machine fixed to the carriage and comprising said handling device. Advantageously, the mobile unit can move in a substantially horizontal plane. Optionally, it may be provided with an actuator which moves said positioning device in the vertical direction, its action making it possible to pre-position at altitude before moving the mobile support on the vertical guide member. Advantageously, it is also provided with an actuator which makes it possible to place said positioning device so that the translational axis B of the second frame is substantially parallel to the X direction of the long side of the electrolysis cell.

The invention further relates to a method for removing at least one hood from an aluminum production cell by igneous electrolysis, characterized in that: a) at least one mobile unit according to the invention provided with at least one a cap handling device according to the invention; b) placing said mobile unit so that said positioning device is in a predetermined initial position, the translation axis B of the second frame being substantially parallel to the direction X; c) maneuvering the articulated arm, the first frame and / or the second frame and, optionally, the gripping system, so as to put the gripping members of the gripping system in the gripping position of said covers; d) the grippers are actuated so as to grip said hoods; e) operating the articulated arm, the first frame and / or the second frame and, optionally, the gripping system, so as to remove said covers and transport them into a specific storage area.

Advantageously, said articulated arm comprises a fixed member secured to the movable support and a movable member whose first end is fixed to the fixed member so as to be pivotable about an axis C, substantially parallel to the axes A and B, and whose second end is fixed to the first frame allowing it to pivot about said axis A. In this way, by combining the rotation of the movable member about the axis C and the rotation of the first frame about the axis A, one may impose on the gripping members a generally planar trajectory, in a plane substantially perpendicular to the direction X, tending to move said hoods away from the frame of the superstructure on which they usually rest, said trajectory being at the beginning preferably substantially normal to the surface of said covers. Optionally, a movement of low amplitude oscillations in the X direction is imposed on the second frame, which facilitates the extraction of the covers.

The invention also relates to a method for setting up at least one hood of an igneous electrolysis aluminum production cell characterized in that: a) at least one mobile unit according to the invention provided with at least one cap handling device according to the invention; b) moving said mobile unit to a specific storage area of the covers and actuating the gripper so as to grip said covers; c) placing said mobile unit provided with said covers so that said positioning device is in a predetermined initial position, the translational axis B of the second frame being substantially parallel to the direction X; c) maneuvering the articulated arm, the first frame and / or the second frame and, optionally, the gripping system, so as to put the gripping members of the gripping system in the position of removal of said covers; d) actuating the gripping members to release said covers; e) operating the articulated arm, the first frame and / or the second frame and, optionally, the gripping system, so as to distance said positioning device from said covers.

The invention also relates to a method for replacing anodes in an electrolysis cell characterized in that it comprises a step where at least one cover located in the vicinity of said anode is removed by following the bonnet removal process according to the invention, described above and a step where, after replacement of said anode, said at least one cover is replaced by following the bonnet implementation method according to the invention described in the previous paragraph.

The invention is described in more detail below with the aid of the appended figures.

Figure 1 illustrates, in section, a typical electrolysis room for the production of aluminum and comprising a service unit shown schematically.

Figure 2 illustrates, in cross-sectional view, a typical electrolysis cell for the production of aluminum.

FIG. 3 is a perspective view of part of the electrolysis cell of FIG.

Figure 4 illustrates a cap handling device according to a preferred embodiment of the invention. FIGS. 5A and 5B show, from two different angles of view, a portion of the device for handling the covers of FIG. 4.

Figures 6A and 6B illustrate the operation of the cover handling device according to the invention in the variant which comprises an articulated frame.

Figures 7 and 8 illustrate embodiments of an advantageous variant of the cap handling device according to the invention.

Figures 9 to 15 illustrate the operation of the cap handling device according to the invention.

Electrolysis plants for aluminum production have a liquid aluminum production zone that includes one or more electrolysis rooms (1). As illustrated in Figure 1, each electrolysis room (1) comprises electrolysis cells (2) and at least one service unit (4). Service units are often referred to as "electrolysis service machines" or "M.S.E" ("PTA" or "Pot Tending Assembly" or "PTM" or "Pot Tending Machine" in English).

As illustrated in FIG. 2, each electrolysis cell (2) comprises a tank (20), a support structure (30) called a "superstructure" and a plurality of anodes (40, 40 '). The vessel (20) comprises a steel box (21), an inner liner (22), which is generally formed of blocks of refractory material, and a cathode assembly (23, 24), which comprises blocks of carbon material, so-called "cathode blocks", (23) and metal connecting bars (24) to which are attached the electrical conductors (50, 51, 52) for routing the electrolysis current. Each anode is provided with a metal rod (41, 41 '), which is typically attached to the anode via a multipode (42). The anodes (40, 40 ') are removably attached to a movable metal frame (25), referred to as the "anode frame", by a removable connector (26, 26'). The anode frame (25) is carried by the superstructure (30) and fixed to electrical conductors (52), called "positive ascents", for the routing of the electrolysis current.

The electrolysis cells (2) are normally arranged in rows or rows, each row or line typically having more than one hundred cells, and electrically connected in series by means of connecting conductors (50, 51, 52). . The cells (2) are arranged to clear a circulation aisle (3) along the electrolysis room (1) and an access path (3 ') between the electrolysis cells.

The electrolysis cell (2) is provided with a rollover system, illustrated in FIGS. 2 and 3. The rollover system comprises a series of removable covers (33) which are typically metallic, and more typically of aluminum alloy . The rollover system confines the effluents within the cell (29) and is connected to means (not shown) for discharging the effluents and directing them to a treatment center. The removable covers (33) are typically inserted into a guide groove (35) arranged along the cell and are supported on a flange (31) of the superstructure. The covers (33) are generally provided with a handle (34) for handling by operators. The rod (41, 41 ') of the anodes typically emerges from the rollover system through openings (32) provided for this purpose in the rollover system.

According to the most widespread technology, the anodes (40, 40 ') are made of precooked carbon material. The progressive consumption of the anodes during the electrolytic reduction reactions of aluminum requires interventions on the electrolysis cells including, in particular, the replacement of the spent anodes (40 ') with new anodes (40).

The service unit (4) is used to carry out operations on the electrolysis cells (2) such as the anode changes or the filling of the ground bath supply hoppers and the AlF ₃ of the electrolysis cells. It can also be used to handle various loads, such as tank elements, pockets of liquid metal or anodes. As illustrated in Figure 1, the service unit (4) comprises a movable bridge (5) which can be translated over the electrolysis cells (2) and a service machine (6). The service machine (6) comprises a mobile carriage (7) and a service module (8) equipped with several handling and intervention devices (10), such as tools (shovels, keys, stitches, etc.). ). The movable bridge (5) rests and circulates on raceways (9, 9 ') arranged parallel to each other and to the main axis of the hall (and the queue of cells). The mobile bridge (5) can thus be moved along the electrolysis room (1). The movable carriage (7) can be moved along the movable bridge (5).

The service machines (6) used for the anode changing operations are equipped with a determined set of tools (10), typically a picker, bucket shovel, anode gripper (called "anode clamp") and a hopper provided with a retractable conduit. The breaker serves to break the crust of alumina and solidified bath which generally covers all or part of the anodes of the cell; the bucket shovel serves to clear the location of the anode, after removal of the spent anode, by removing solids (such as pieces of crust and alumina) therein; the anode clamp is used to grip and manipulate the anodes by their rod, in particular for the removal of spent anodes from an electrolysis cell and the placement of new anodes in the electrolysis cell; the retractable conduit is used to introduce alumina and / or ground bath in the electrolysis cell, so as to reform a coating layer, after the establishment of a new anode. The breaker, the bucket and the anode clamp are typically mounted at the lower end of a guide member, such as a mast or a telescopic arm.

The change of a spent anode (40 ') by a new anode (40) requires the prior removal of a determined number of covers (33) located near the spent anode (40'), their temporary storage and their refitting at the end of the anode change operations. According to the invention, the covers are handled using a handling device (100) which comprises a positioning device (110) and a gripping system (160) of the covers.

In a preferred embodiment of the invention, the positioning device (110) comprises:

a vertical guide member (101);

a movable support (120), such as a carriage, mounted on the guide member (101) so that it can be moved at least in a vertical direction in use; an articulated arm (130) mounted on the mobile support (120);

- a first frame (140) mounted on the articulated arm (130) so as to be pivotable about a first substantially horizontal axis of rotation A in use;

- a motor (141) for pivoting the first frame (140) about said first axis of rotation A; - a second frame (150) mounted on the first frame (140) so as to be movable along a first translation axis B determined, which is substantially horizontal in use (and typically parallel to the axis A);

means (151, 152, 153, 154, 155) for moving the second frame (150) along said first translation axis B.

The vertical guide member (101) typically comprises a fixed member (102) and at least one movable member (103, 103 ') and the movable support (120) is mounted on the one or one of the movable members (103, 103' ). The vertical guide member (101) is typically selected from the telescopic masts. In the embodiment illustrated in FIGS. 4 to 8, the vertical guide member (101) is a telescopic mast comprising a fixed shaft (102), a first sliding shaft (103) and a second sliding shaft (103 ') and the movable support (120) is mounted on the second sliding shaft (103 '). The movable support (120) is typically driven by a motor (121).

The articulated arm (130) serves to move the covers in a direction substantially perpendicular to the long sides of the electrolysis cells. The first frame (140) serves to adjust the inclination of the covers (33) relative to the electrolysis cell (2). The second frame (150) allows a lateral deflection of the covers (33), that is to say in a direction substantially parallel to the long sides of the electrolysis cells. These movements allow precise positioning of the covers during their handling and are performed in a first tolerance range determined, which is typically of the order of ± 0.5 cm.

In the exemplary embodiments illustrated in Figures 4 to 8, the articulated arm (130) comprises a fixed member (131) integral with the movable support (120) and a movable member (132). A first end of the movable member (132) is fixed to the fixed member (131) so as to be pivotable about a second axis C, which is substantially horizontal in use, with a motor (133). A second end of the movable member (132) is attached to the first frame (140) and allows it to pivot about said first axis of rotation A.

In the examples of FIGS. 4 to 8, the displacement means (151 to 155) of the second frame (150) comprise a motor (151) fixed to the first frame (140) and provided with a pinion (152), a rack (153) secured to the second frame (150) and in which the pinion (152) engages, guides (154) and bearings (155) slidably mounted on the guides (154).

The gripping system (160) of the covers comprises a determined set of grippers (161) for gripping a determined set of hoods (33) in a determined number of attachment points. The gripping system (160) of the covers is attached, directly or indirectly, to the second frame (150).

Interventions on electrolytic cells, including anode-change operations, typically require the removal of multiple hoods at a time. The determined set of covers (33) typically comprises at least three covers (33). Figures 4 to 8 illustrate a case where the device allows to handle four covers simultaneously. In order to substantially reduce the mechanical oscillations of the covers during their handling and thus to ensure a high accuracy of their positioning, the number of attachment points is preferably greater than or equal to three per cover and said points are preferably arranged so to form a plan. The covers (33) thus remain substantially immobile (and typically parallel) with respect to the second frame (150) during handling.

The gripping members (161) may be chosen from any known gripping means, such as hooks or electromagnets. However, in order to be able to capture hoods without gripping means complementary to those of the gripping system (160), the gripping members (161) are advantageously suction pads activated by a pneumatic system. In the embodiment illustrated in Figures 4 to 8, the number of suction cups, and therefore fixing points, is four per bonnet, which increases the reliability of the device. Advantageously, the gripping system (160) further comprises blowing means for blowing said fixing points on the hood or hoods before the activation of said suction cups.

The gripping system (160) advantageously comprises an articulated frame (162) comprising a fixed frame (169) fixed to the second frame (150), at least one hinged frame (163, 163 ') fixed to the fixed frame (169) by a at least one hinge (164, 164 ') so as to be pivotable about an axis (D, D') which is substantially vertical in use, and, for each hinged frame (163, 163 '), an actuator (165, 165 ') for pivoting the or each hinged frame (163, 163') about said axis. Said actuator (165, 165 ') is typically a jack. This variant of the invention is particularly advantageous when the electrolysis cells have positive rises (52) close together. Indeed, for such cells, the width covered by the determined set of covers is generally greater than the distance between two adjacent positive risers. In this case, the articulated frame (162) makes it possible to retract one of the covers of the assembly, placing it typically perpendicular to the plane of the other covers, as illustrated in FIGS. 6A and 6B, which makes it possible to reduce the total width of the cover assembly and to pass between the positive risers (52).

The hinged frame (162) preferably comprises two hinged frames (163, 163 ') arranged to form a triptych. More specifically, the hinged frame (162) preferably comprises a first hinged frame (163) fixed to a first end of the fixed frame (169) by at least a first hinge (164), a first actuator (165) intended to rotate the first articulated frame (163) around a first axis D, a second articulated frame (163 ¹ ) fixed to a second end of the fixed frame (169) by at least a second hinge (164 '), and a second actuator ( 165 ') for pivoting the second hinged frame (163') about a second axis D 'with a second actuator (165'). This variant of the invention makes it possible to place one or the other of the end covers perpendicularly to the plane of the other covers. It is particularly advantageous in cases where the set of covers to be handled comprises one or more covers which are located under positive risers on one side or the other of the handling device (100). Figures 6A and 6B illustrate this variant of the invention.

In order to facilitate the clearance of a space sufficient to allow the pivoting of said frame (163, 163 '), the articulated frame (162) is advantageously mounted on the second frame (150) so as to be able to be moved along a second determined translation axis B ', which is substantially horizontal in use and which is typically parallel to said determined first translation axis B, and the positioning device (110) of the covers comprises means (166, 167, 168), such that a guided actuator for moving the articulated frame (162) along the second translation axis B ', which is typically parallel to the first translation axis B. In the embodiments illustrated in FIGS. 4 to 8, said displacement means (166,

167, 168) of the articulated frame (162) comprise guides (166) mounted on the second frame (150), bearings (167) integral with the hinged frame (162) and mounted on the guides so as to be slidable along the these, and a linear actuator (168), such as a rodless cylinder. These means are sufficient to ensure the displacement of the articulated frame (162) between two end positions. FIG. 9 illustrates an example of operation of this variant of the invention in the embodiment, illustrated in FIGS. 4 to 8, in which the handling device (100) makes it possible to manipulate four covers (33a, 33b, 33c, 33d). simultaneously. The electrolysis cell is partially shown in view from above. In this example, three of the covers (33a, 33b, 33c) are located between two successive positive risers (52, 52 ') and the fourth cover (33d) is located under one of the two positive risers (52'). The anode to be changed, whose rod (41 ') is shown in section, is located behind the third hood (33 c), starting from the left. The hinged frame (162), the gripping members (161a, 161b, 161c, 16Id) and the first frame (140) are shown schematically. As shown in FIG. 9 (A), the handling device (100) is initially positioned so that the first frame (140) faces the anode to be changed and the gripping members (161a, 161b, 161c, 16Id) opposite each of the corresponding covers (typically near the vertical axis of each cover). The articulated frame (162) is then partially under the right positive rise (52 '). The gripping members (161a, 161b, 161c, 16Id) are applied to the covers and activated so as to grasp them. The hoods are then released from their location and slightly raised. The first cover (33 a) is retracted, typically by a 90 ° pivoting of the left hinged frame (163) relative to the plane of the other covers (as shown in Figure 9 (B)). As shown in FIG. 9 (C), the articulated frame (162) is shifted to the left, which allows the handling device to remove all the covers without being impeded by the positive rises (52, 52 '). ).

In an advantageous variant of the invention, the device (100) for handling the covers further comprises a cleaning means (180, 180 ') which is mounted on a second articulated arm (170). The cleaning means (180, 180 ') serves in particular to remove the dust and scrap debris and anode left by the anode changing operations, especially in the guide grooves (35), before the repositioning hoods. The cleaning means (180, 180 ') is typically selected from brushes, doctor blades and / or blowing means. FIGS. 7 and 8 illustrate embodiments of this variant in which the second articulated arm (170) is mounted on the first frame (140). In these examples, the articulated arm (170) comprises a first (171) and a second (172) movable member interconnected by a pivot point, the first movable member (171) is fixed to the first frame (140) so as to be pivotable about a first hinge axis, which is typically horizontal in use, with a first motor (173), the hinged arm (170) has a second motor (174) for pivoting the second movable member (172) about a second hinge axis passing through the hinge point, and the cleaning means (180, 180 ') is attached to the second movable member (172). In the example of Figure 7, the cleaning means (180) is a brush which is attached to the second movable member (172) by a lever (176) so as to be pivotable about a third hinge pin to using a third motor (175), optionally coupled via a gear (177). The brush (180) is typically a rotating brush powered by a motor (181). In the example of Figure 8, the cleaning means (180 ') is a doctor blade actuated by a third motor (175'). The second articulated arm (170) may optionally be mounted on a separate handling device (100).

The device (100) for handling the hoods according to the invention may comprise means for locking the hoods on the gripping system (160) as complementary safety securing means in the event of malfunctioning of the gripping members. Preferably, to ensure the reliability of the locking, the locking means are mechanical means. For example, the locking means may comprise a hook mounted on a rotary jack and adapted to fit into the handles (34) of the hood (33).

In order to allow automation of the handling of the covers (33), the handling device (100) according to the invention can be equipped with a computerized control system. This control system can perform pre-programmed operations and / or execute autopilot programs. For these purposes, the handling device (100) covers advantageously comprises an encoder and a detection system capable of detecting the presence of covers, their orientation and their position. This variant of the invention makes it possible to effectively locate the hoods, which, although that they are in principle placed in certain places, can be displaced with respect to their theoretical position, although generally in a certain tolerance domain. The signals relating to the presence of said covers, their orientation and their position are transmitted to said encoder which converts them into digital data for the control system. The detection system typically includes at least one telemetry system, such as a laser range finder. For example, the detection system may comprise a set of two rangefinders configured to detect the presence of a reflection-determined cover and to measure the orientation and position of this cover. The detection system may advantageously be used to detect the presence of surface patterns and / or elements determined on the covers in order to avoid or impose placing the gripping members (161) on these elements or patterns. For example, when the hoods are provided with one or more handles and stiffeners, the detection system can be used to detect the position of the handles, which are generally significantly elevated relative to the hoods and therefore easier to differentiate from the hoods. , and use the position of the handles as pins for positioning the grippers (161) relative to the covers.

In order to be able to control the distance between at least one predetermined point on the handling device (100) and a point on an electrolysis cell, the handling device (100) according to the invention advantageously comprises a telemetry system configured in a manner to measure this distance. The reference point determined on the cell is typically located on the anode frame, the anode rods or the covers. The telemetry system is advantageously chosen from rangefinders (typically laser rangefinders), spatial configuration analyzers and cameras equipped with an image analyzer. This variant of the invention makes it possible, for example, to check the distance between the gripping members (161) and points determined on an electrolysis cell, and therefore the distance between the captured caps and said points, so as to position very precisely the covers with respect to the cell. The device (100) handling of covers according to the invention is intended to be mounted on a transport device, such as a service unit (4), a service machine (6) or a self-propelled vehicle able to move in the circulation aisle (3) and in the access ways (3 '). A cap handling device (100) can thus serve several distinct cells. The transport device is intended for interventions on the electrolysis cells (2) for the production of aluminum. In order to simplify the task of the operators, the device (100) for handling the covers according to the invention is advantageously mounted on a service unit (4) or a service machine (6) intended for anode change operations, possibly on the same service machine (6) which comprises said determined set of tools (10).

The transport device is used to set up the positioning device (110) near the hood or the set of covers (33) which is to be handled. This relatively coarse approach is performed in a second defined tolerance range, which is typically of the order of ± 1 cm.

The replacement of a spent anode (40 ') with a new anode (40) is typically carried out according to a method in which: - a service machine (6) is placed in the vicinity of said determined set of tools (10). of the determined spent anode (40 ');

a given number of hoods (33) located near the worn anode (40 ') are removed and stored close to their place of origin, generally by depositing them on adjacent hoods; the metal rod (41 ') of the spent anode (40 ¹ ) is gripped using an anode clamp;

the connector (26 ') of the spent anode is loosened and the connector is removed by means of a connector handling tool, which can be mounted on the service machine used for the anode changes; the used anode (40 ') is removed from the electrolysis cell by means of the anode clamp and is deposited in a determined location; - A replacement anode (40) is gripped using a handling tool, usually the same anode clamp that was used to handle the spent anode, and is placed in the location initially occupied by the worn anode;

- the replacement anode (40) is fixed to the anode frame (25) by means of a connector (26);

- We replace the hoods (33) in their original place.

The handling of the covers can be carried out using the device (100) for handling the covers according to the invention. It typically includes the following operations:

- The transport device provided with a handling device (100) is placed near the worn anode (40 ') to be changed, typically by reference to its metal rod (41'). This maneuver, which can be performed automatically if the device is equipped with a computerized control system, is intended to place the positioning device (110) in a given position relative to the covers to be removed, with a determined precision, of the order of ± 2 cm, preferably ± 1 cm. This position constitutes a point of reference for the subsequent movements of the members of the handling device (100).

- The vertical guide member (101) and / or the movable support (120) is actuated so as to place the mobile support (120) at a height determined with respect to the level of the access path (3 ').

- Maneuvering the articulated arm (130), the first frame (140), the second frame (150) and, optionally, the gripping system (160), so as to put the gripping members (161) of the gripping system (160) in the gripping position of said covers.

- The grippers (161) are actuated so as to capture the determined covers (which are four in Figures 4 to 8). The articulated arm (130), the first frame (140), the second frame (150) and, optionally, the gripping system (160) are maneuvered so as to remove the said covers and transport them to a zone of determined storage. The determined storage area is advantageously set back from the working area required for the anode change operations. In order to ensure the precision required for the replacement of the covers after the change of the anode, the covers preferably remain attached to the gripping members (161) during all the anode change operations and until they are reset. square.

- After the anode change operations, the articulated arm (130), the first frame (140), the second frame (150) and, optionally, the gripping system (160) are maneuvered so as to put back said covers in their original place. Before replacing the covers, it is generally preferable to remove the crust and anode dust and debris left behind by the anode change operations. This cleaning can be done manually or with the aid of said cleaning means (180, 180 '). The use of the cleaning means (180, 180 ') according to the invention allows a thorough automation of the handling of the covers.

When capturing the covers, it is advantageous to check that the gripping members (161) actually grip the covers. This control can be performed automatically by means of complementary measuring means and / or the activation system of the gripping members. For example, it is possible to check the gripping of the hoods with the aid of a detection system able to detect the presence of the hoods and / or, in the variant of the invention where these bodies comprise suction cups, with the aid of a measure of the pressure in the pneumatic system. As a safety measure, it is possible to prohibit the movement of the covers if a cover is not gripped by a minimum number of gripping members (161); for example, if the gripping system (160) comprises four grips per cover, it can prohibit movement if a cover is not grasped by at least three of these bodies. An operator can then intervene to verify the origin of the failure. The movement of the covers during removal, storage and refitting is done in a manner that does not touch the positive risers and the covers left in place. The movements of the second frame (150) are generally made necessary when at least one of the covers of the assembly is located between a positive rise (52) and the tank (20). In this case, the maneuvers typically include positioning said set of covers at a determined distance from the plane of the covers left on the cell, so as to place them at a distance sufficient not to hang the handles of the covers left on the cell , and a lateral displacement of the set of covers.

Advantageously, during the removal of the covers, it is possible to generate an oscillating movement of the covers, which is substantially horizontal and of small amplitude (typically less than approximately 10 mm, and more typically between 1 and 10 mm), by placing in corresponding motion of the second frame (150). This movement is intended in particular to facilitate the extraction of the covers in cases where they would be tightened by the adjacent covers or their establishment in cases where the space left by the covers already in place on the electrolysis cell would be insufficient.

In the variant of the gripping system (160) comprising displacement means (166, 167, 168) of the articulated frame (162), the maneuvering of the gripping system (160) can include, in addition to the movement of the frame (s) (163). ), lateral movements of the articulated frame (162) by actuating the displacement means (166, 167, 168). These lateral displacements are generally required when the width covered by the set of covers attached to the gripping system (160) is greater than the distance separating two adjacent positive risers. In this case, the one or one of the frames (163) is placed perpendicular to the plane of the other covers by means of the actuator (165, 165 '), which reduces the total width of the set of covers, and moves the hinged frame (162) towards said frame by means of the displacement means (166, 167, 168), so as to place all the covers in a position which allows them to slide between the two adjacent positive risers without hanging them. In the variant of the handling device (100) comprising a detection system, the handling operations of the covers advantageously include a measurement of the position and orientation of the covers to be seized by the device. These measurements make it possible to carry out with greater precision the maneuvers for setting the grasping system (160) into the gripping position. These measures also allow the precise replacement of the covers after the anode change operations. These measures also allow complete automation of the maneuvers.

As illustrated in FIGS. 10 to 12, the handling of the covers can be carried out according to a method in which:

the handling device (100) is placed in an initial position (FIG. 10);

the moving support (120) is lowered (FIG. 11);

the gripping members (161) are placed in the catching position of the covers (33) by moving the gripping system (160) using the articulated arm (130), the first frame (140) and the second frame ( 150) (Figure 12);

the covers (33) are released from their position and lifted up to a determined position (FIG. 13);

optionally, the hoods (33) are moved laterally and, optionally, one or more hoods are retracted, as shown in FIG. 9, so as to allow the complete removal of all the hoods seized by the handling device (100);

the covers (33) are placed in a determined position (FIG. 14);

the covers (33) are removed from the intervention zone on the cell and the handling device (100) is placed in a determined standby position, which is preferably sufficiently far from the cell to not interfere with the operations. anode change itself (Figure 15).

Replacing the covers (33) can follow a similar process, reversing the order of operations.

Claims

1. A device (100) for handling the covers (33) of an igneous electrolysis aluminum production cell (2) characterized in that it comprises: a positioning device (110) comprising a vertical guide member (101), a movable support (120) mounted on the vertical guide member (101) so that it can be moved at least in a vertical direction in use, an articulated arm (130) mounted on the movable support (120) a first frame (140) mounted on the articulated arm (130) so as to be pivotable about a substantially horizontal first axis of rotation A in use, said articulated arm (130) being at least able to move away and bring the first frame (140) of the movable support (120), a motor (141) for pivoting the first frame (140) about said first axis of rotation A, a second frame (150) mounted on the first frame (140) so as to to be movable along a first axis of translat determined ion B, which is substantially horizontal in use, and means (151 - 155) for moving the second frame (150) along said first translation axis B; - A gripping system (160) of the covers attached to the second frame (150) and comprising a determined set of grippers (161) for gripping a determined set of covers (33) in a fixed number of fixing points.

Handling device (100) according to claim 1, characterized in that the vertical guide member (101) comprises a fixed element (102) and at least one movable element (103, 103 ') and in that the mobile support (120) is mounted on the or one of the movable elements (103, 103 ').

3. handling device (100) according to claim 2, characterized in that the vertical guide member (101) is selected from the telescopic masts.

4. Handling device (100) according to any one of claims 1 to 3, characterized in that the displacement means (151 - 155) of the second frame (150) comprises a motor (151), fixed on the first frame (140) and provided with a pinion (152), a rack (153) integral with the second frame (150) and in which the pinion (152) meshes, guides (154) and bearings

(155) slidably mounted on the guides (154).

5. handling device (100) according to any one of claims 1 to 4, characterized in that the number of attachment points is greater than or equal to three per cover and in that said points are arranged to form a plan.

6. Handling device (100) according to any one of claims 1 to 5, characterized in that the gripping members (161) are suction pads activated by a pneumatic system.

7. Handling device (100) according to claim 6, characterized in that the gripping system (160) further comprises blowing means for blow-cleaning said attachment points on the hood or caps before the activation of said suction cups.

8. Handling device (100) according to any one of claims 1 to 7, characterized in that the gripping system (160) comprises an articulated frame (162) comprising a fixed frame (169) fixed to the second frame (150). ), at least one hinged frame (163, 163 ') fixed to the fixed frame (169) by at least one hinge (164, 164') so as to be pivotable about an axis (D, D ') which is substantially vertical in use, and, for each hinged frame (163, 163 '), an actuator (165, 165') for pivoting the or each hinged frame (163, 163 ') about said axis.

9. Handling device (100) according to claim 8, characterized in that the articulated frame (162) comprises two articulated frames (163, 163 ') arranged to form a triptych.

10. Handling device (100) according to any one of claims 8 and 9, characterized in that the articulated frame (162) is mounted on the second frame (150) so as to be movable along a second defined translation axis B ', which is substantially horizontal in use and which is typically parallel to said first determined translation axis B, and in that the positioning device (110) of the covers comprises means (166, 167, 168) for moving the articulated frame (162) along the second translation axis B '.

11. Handling device (100) according to claim 10, characterized in that said displacement means (166, 167, 168) of the articulated frame (162) comprises a guided actuator.

12. Handling device (100) according to claim 10 or 11, characterized in that said displacement means (166, 167, 168) of the articulated frame (162) comprise guides (166) mounted on the second frame (150). , bearings (167) integral with the hinged frame (162) and slidably mounted on the guides, and an actuator (168).

13. The handling device (100) according to any one of claims 1 to 12, characterized in that it further comprises a cleaning means (180, 180 ') mounted on a second articulated arm (170).

14. Handling device (100) according to claim 13, characterized in that the cleaning means (180, 180 ') is selected from brushes, scrapers and / or blowing means.

15. Handling device (100) according to any one of claims 1 to 14, characterized in that it is equipped with a computerized control system.

16. Handling device (100) according to claim 15, characterized in that it comprises an encoder and a detection system capable of detecting the presence of the covers, the orientation of the covers, the position of the covers and / or the presence of surface patterns and / or elements determined on the covers.

17. Handling device (100) according to claim 16, characterized in that the detection system comprises at least one telemetry system.

18. Handling device (100) according to claim 17, characterized in that the telemetry system is a laser rangefinder.

19. Handling device (100) according to any one of claims 1 to 18, characterized in that it comprises a telemetry system configured to measure the distance between at least one point on the handling device (100 ) and a dot on an electrolysis cell.

20. Handling device (100) according to claim 19, characterized in that the telemetry system is selected from rangefinders, spatial configuration analyzers and cameras provided with an image analyzer.

21. Service machine (6) of a series of aluminum production cells by igneous electrolysis (2) comprising a plurality of covers (33), characterized in that it comprises at least one handling device (100). caps according to any one of claims 1 to 20.

22. A mobile unit capable of moving in the electrolysis room of an igneous electrolysis aluminum production plant characterized in that it comprises at least at least one device (100) for handling hoods according to one of the following: any of claims 1 to 20.

23. Mobile unit according to claim 22 characterized in that it is provided with a control system ensuring that said positioning device is placed in a position determined with respect to the cover or to the plurality of covers to be handled, said determined position being able to be defined by a distance ΔX along the X direction of the long side of the electrolysis cell, a distance ΔY in the Y direction of the small one side of the electrolysis cell and a difference in altitude .DELTA.Z between a characteristic point of the handling device and a characteristic point of the plurality of covers to be handled.

Mobile unit according to claim 22 or 23, provided with an actuator which makes it possible to place said positioning device in such a way that the translational axis B of the second frame (150) is substantially parallel to the direction X of the long side of the electrolysis cell.

25. Mobile unit according to any one of claims 22 to 24 characterized in that it is a self-propelled vehicle that can move in a substantially horizontal plane and in that it is optionally provided with an actuator moving said positioning device. following the vertical direction.

Mobile unit according to any one of claims 22 to 24, characterized in that it is a service unit (4) of an igneous electrolysis aluminum production plant comprising a movable bridge (5) and at least one a service machine (6) according to claim 21.

27. Mobile unit according to claim 26 wherein said movable bridge moves in the Y direction of the short side of the electrolysis cell and in that said service machine is secured to a carriage moving in the direction X of the large side of the electrolysis cell.

28. A process for removing at least one hood from an igneous electrolysis aluminum production cell characterized in that: a) at least one mobile unit according to any one of claims 22 to 27 is used; b) placing said mobile unit so that said positioning device is in a predetermined initial position, the translational axis B of the second frame (150) being substantially parallel to the direction X; c) operating the articulated arm (130), the first frame (140) and / or the second frame (150) and, optionally, the gripping system (160), so as to put the gripping members of the system of gripping in the gripping position of said covers; d) the grippers are actuated so as to grip said hoods; e) maneuvering said articulated arm, said first frame and / or said second frame and, optionally, the gripping system, so as to remove said covers and transport them into a specific storage area.

29. The method of claim 28 wherein a positioning device with an articulated arm (130) comprises a fixed member (131) integral with the movable support (120) and a movable member (132) whose first end is fixed to the member fixed so as to pivot about an axis C, substantially parallel to the axes A and B, and whose second end is fixed to the first frame (140) allowing it to pivot about said axis A, so that by combining the rotation of the mobile member about the axis C and the rotation of the first frame about the axis A, it is possible to impose a globally flat trajectory, in a plane substantially perpendicular to the direction X of the long side of the electrolysis cell.

30. The method of claim 29 wherein imposing on the second frame a movement of small amplitude oscillations in the X direction, which facilitates the extraction of the covers.

31. Method for setting up at least one cover of an igneous electrolysis aluminum production cell characterized in that: a) at least one mobile unit according to any one of claims 22 to 27 is used; b) bringing said mobile unit up to a determined storage area of the covers and actuating the gripping device so as to grip said covers; c) placing said mobile unit provided with said covers so that said positioning device is in a predetermined initial position, the translational axis B of the second frame being substantially parallel to the direction X; c) maneuvering the articulated arm, the first frame and / or the second frame and, optionally, the gripping system, so as to put the gripping members of the gripping system in the removal position of said covers; d) actuating the gripping members to release said covers; e) operating the articulated arm, the first frame and / or the second frame and, optionally, the gripping system, so as to distance said positioning device from said covers.

32. A method for replacing the anodes in an electrolysis cell, characterized in that it comprises a step in which at least one cover located in the vicinity of said anode is removed by following the method of removing the hood according to any one of the Claims 28 to 30 and a step where, after replacement of said anode, said at least one cover is replaced by following the bonnet placement method of Claim 31.