ES2203037T3 - LIFTING DEVICE FOR THE REPLACEMENT OF THE ANODES IN THE ELECTROLYSIS CUBES FOR ALUMINUM PRODUCTION. - Google Patents

Abstract

Tool-holder module intended to be used within a lifting installation, which comprises two independently motorized lifting elements: a first organ, consisting of a lifting system comprising at least one cable (13), one or two electrically motorized drums (14), a hoist (18) at the level of which a tool holder is fixed, said or said cables (13) being wound on said or said drum (s) (14), and being forwarded (s) ) at the level of the hoist (18), said first lifting member being designed to ensure the movement of a load at the level of the hoist (18) at a relatively important speed, and according to an extended stroke; a second organ, of which one of the constituent elements is in solidarity with the end of the cable (13) of said first organ after forwarding at the level of the hoist (18), and comprising means that allow to ensure in cooperation with said hoist the vertical displacement at reduced speed and according to a limited stroke of a more important load.

Description

Lifting device for the replacement of anodes in the electrolysis tanks for the production of aluminum.

The present invention relates in a manner general to the change of spent anodes within the vats of Aluminum production electrolysis. It refers very particularly to a module capable of allowing extraction proper of the spent anodes and the installation that Use these modules.

Aluminum is produced industrially by the currently well known procedure of igneous electrolysis, that is to say that it uses the alumina electrolysis in a bath of molten cryolite according to the reaction:

         \ dotable {\ tabskip \ tabcolsep # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 Al 2 O 3 + 2E - + \ +
Na3 [Alf6] → 2Al + 3O2 + 3C
 ? 3CO2 + F \ cr Alumina \ + \ hskip0.2mm
Cryolite \ cr}
      

This strongly exothermic reaction uses therefore a melt bath comprising a mixture of cryolite and alumina, whose temperature is generally above 800 ° C, and is very consuming of electricity, so that the facilities they operate on a continuous basis, in order to limit the losses of energy inherent to the newly commissioned phases.

Regularly, proceed to replace the the different anodes, very often made of coal, at the level of each of the vats, without stopping the reaction of the electrolysis.

By the procedure used, namely the igneous electrolysis, an upper surface of the bath is formed hard crust of fluorinated cryolite and alumina, presenting this crust the advantage of conserving heat in the bathroom, and by both of creating a heat-insulating envelope.

However, the extraction of spent anodes outside the bathroom you need the breakage of this scab and, experience shows that the effort needed to plucking a worn anode from said scab is seven to eight times greater than the mass of a new anode.

Moreover, this effort only lasts some centimeters of stroke while the lifting stroke of the anode in each cycle is of the order of three to four meters, typically 3.50 m.

Currently, in existing facilities, it they use, in order to carry out these operations, systems of hydraulic jacks, which currently have a single limited volume that allows its integration into the available volume above the vats.

It has been described in the document US-A-5 816 565 a system of lift that uses two lifting organs that interact each.

However, whatever the quality of the oil used at the level of these hydraulic jacks, taking into the high temperature of the melting bath counts, the risk of Fire is permanent and, you want to avoid this inconvenience Redhibitory

The solutions proposed until then for avoid the use of the hydraulic extraction system with a problem of volume and civil engineering of the existing facilities Indeed, these solutions, which use typically a cable system, require a volume widely superior, incompatible with these facilities or, they need the realization of new facilities, which aggravate too much significant corresponding costs before being susceptible If amortized.

The object of the invention is therefore to propose an installation for the exchange of spent anodes within a series of electrolysis tanks, avoiding these inconveniences, and in particular compatible with existing factories and avoiding risks inherent in the use of hydraulic devices. The invention refers first to a module tool holder, intended in particular to receive a tool to allow starting and transfer of worn anodes This tool holder can also integrate any type of tool, and in particular a device capable of breaking the upper crust that forms in the bathroom surface, but also a shovel or similar, intended for collect the pieces of scab from this break.

This tool holder module, intended to be used within an installation of elevation, is characterized in that it is provided with two organs of  lift motorized independently:

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a first organ, constituted by a lifting system comprising at least one cable, one or two electrically motorized drums, a hoist at the level of which a tool holder, said or said winding cables to be wound on said or said drum (s), and being Forwarded (s) at the hoist level, said first being lifting body designed to ensure the movement of a Hoist level loading with relatively important speed, and according to an extensive career;

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one second organ, of which one of the constituent elements is in solidarity with the end of the cable or wires of said first organ after forwarding at the hoist level and comprising means that allow to secure in cooperation with said hoist vertical displacement at reduced speed and according to a run Limited of a more important load.

The invention therefore consists of a first moment, in differentiating two movements, namely a movement that you need an intense effort in a short race at speed reduced, and a movement that needs a clearly more effort reduced in a much longer run, at a speed too much higher.

Mainly, this module is very particularly suitable for starting and transferring worn anodes In fact, the second organ is intended to allow for intense tensile stress, necessary and sufficient to allow the actual start of the anode spent outside the electrolysis bath, while the first organ, after effective removal of said anode, ensures the movement of this outside the tank.

According to an advantageous feature of the invention, the first organ is constituted by a system of cable lift (s) that supports one or more cables rolled on one or several drums moved by an engine electric, and equipped with a hoist system at the level of which a tool is attached, for example of the anode grip, of breakage of the upper crust of the electrolysis bath or also of a tool that performs the function of recovery blade the pieces that come from that layer.

In parallel, said second body is constituted by a mechanical or electromechanical jack, at the end of which the cable (s) of said first organ are fixed.

In other words, the invention consists in make a lifting system of a load provided with a point fixed, said fixed point being capable of being made mobile in a limited career through said second body, that is in the example case, of a mechanical or electromechanical jack.

Advantageously, the module of a cable loosening, so as to limit the applied load by the tool, of which said module is provided, on a obstacle, and in particular at the bottom of the electrolysis tank. On the other hand, this loosening of cable allows to maintain the perfectly coiled cable turns at the level of the drums, and is also designed not to apply efforts at the level of the placement plane, as will be specified in more detail later.

According to another feature of the invention, the tool holder module comprises a mast of semi-rigid vertical guidance, in solidarity with the said chassis module, and along which a car slides tool holder itself. With this, I know limits the amplitude of the lateral displacement of the hoist, in particular the proximity of the maximum potential run allowed by the length of the cables.

The invention also relates to the installation for changing worn anodes of electrolysis tanks of aluminum production

This installation includes a rolling bridge liable to move over these vats and over the which moves according to a direction perpendicular to the translation from the bridge a carriage equipped with a module tool holder designed to extract and transfer the anodes worn out of the vats, and to drive at the level of these vats new anodes.

This installation is characterized because the car it is provided with a vertical tree that receives a plurality of coaxial crowns, capable of being moved in rotation independently of each other, receiving each of said one or more tool holder crowns, respectively intended:

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to allow break the superficial crust that is created on the upper surface of the electrolysis bath of each one of the tanks;

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to pick up all or part of the pieces that come from the breakage of said crust;

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and to extract and transfer the spent anodes out of the vats and lead to level of these vats new anodes,

said modules being tool holders, and consequently, the tools that support capable of describing some portions of circle arc.

According to the invention, the maximum angle value between two extreme toolholders is ideally inferior to volume of the cockpit, arranged above said tree vertical. In the absence of said cabin, the angle that separates two tools or two extreme tool holders is less than 180º.

In this way, this installation can be used within existing facilities, limiting the maximum interference and interaction risks with in particularly the gas evacuation pipes, especially fluorides and monoxide and carbon dioxide, from each of the vats

The way in which the invention can be realized and the advantages that result from it will stand out better from the example of following embodiment, given as an indicative but not limiting With the support of the attached figures.

Figure 1 is a schematic representation in partial section of an installation according to the invention.

Figure 2 is a representation analogous to the Figure 1, but according to a perpendicular view with respect to the view of figure 1.

Figures 3a, 3b and 3c are representations Schematic plan of the different phases of displacement of the toolholder modules, in particular when a tool activation change takes place.

Figure 4 is a schematic representation concerning the principle of use of the modules tool holder according to the invention, of which figure 5 is a representation of an example of the system of wiring, and Figure 6 is a view above the figure 5.

Figures 7, 8 and 9 are respectively schematic representations of the module perspective tool holder according to the invention, respectively alone and associated with two modules of the same nature, According to two different views.

Figures 10 and 11 are representations Schematic of the operation of the cable loosening performed at the level of said module according to the invention.

A figure 1 has been represented within partial section view of the installation according to the invention. Fundamentally, it consists of a bridge rolling (1), capable of moving in translation on a raceway (5) above an electrolysis tank (2), and more exactly from a series of vats, substantially identical to each other in which a bath of is maintained fusion electrolysis, which contains in a known way cryolite and alumina.

Typically, the bath temperature is higher at 800 ° C, said bath being subjected to a voltage of approximately 4.5 volts, the intensity of the current being electric continuous circulating inside it typically from the order of 180000 to 200000 Amps.

According to the invention, this rolling bridge (1) receives a car (6), capable of traveling on a road rolling (7) perpendicular to the translation of the rolling bridge. East carriage (6) receives a platform (8), which crowns a central tree vertical (9), at the level of which a succession of crowns is mounted coaxial one above the other, respectively (10), (11) and (12).

These different crowns (10), (11) and (12) are liable to be rotated independently of the others by any appropriate means, and in particular by coupling of an electric motor on an appropriate gear (no represented).

Each of these crowns presents a prolongation, located substantially in the same plane, and at the level of which is fixed one or several modules (13, 14, 15) of the type Described below.

More precisely, each crown is associated with a specific tool holder module, respectively:

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a tool for driving new anodes, and starting and evacuation of spent anodes;

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a breakage tool of the upper crust of the bathrooms electrolysis;

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a collection tool, typically a shovel, of all or part of the pieces out of the crust break.

As can be seen well in figures 3a, 3b and 3c, for a configuration with three tools, the angle Maximum between the two extreme tools is less than 120º. From this way, there is always compatibility between the displacement of the carriage (6) and in particular the evacuation tubes (4) of the gases fluorinated and carbonated located at the facility level existing. In particular, these angles can be defined in depending on the characteristics of existing facilities, without cause any modification of these.

Each of the crowns is equipped with a means for controlling the rotation angle of the tool or tool holder that supports, the angle being determined from a fixed point on the tree it supports these crowns.

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Typically, when the installation is equipped with a programmable automaton, designed to automate your operation, an encoder (not shown) mounted on the motor shaft of the crown drag motor in question indicates the angle of rotation of the tool holder from a signal given by a fixed limit switch in rotation.

When the installation is devoid of said programmable automaton, an anti-collision system, of the detector type of proximity, mounted on each tool, is associated with the fixed end of rotation signal, which ensures control relative angle of the tools.

Advantageously, the platform (8) receives a upper cabin (not shown), intended to receive the user, the latter being able to operate the tools in it considered and the tool holders corresponding while monitoring the maneuver.

On the other hand, the tree (9) can also receive a certain number of supplementary coaxial crowns, susceptible to support other tools than those mentioned previously, and in particular an opening tool for covers (3) of the tanks (2) for example, brushes, etc. ....

It is conceived that, since you want to proceed to the activation of one of the tools, the other two are separated moving the intermediate tool, that is the tool positioned between the tool in service and the tool more extreme, on such extreme tool, in order to allow free operation of the tool in desired service.

Thus, in figure 3a, we proceed in principle, after opening the covers, to the use of the breakage tool of the upper crust of the electrolytic bath, also called chopper tool, the other two being tools shifted to the left.

Once the crust break operation done, the chopper tool is shifted to the left in the direction of the starter tool, and the tool that supports the blade undergoes a rotation of 270º, until reaching the level of the place of the tank considered (figure 3b).

To do this, and in order to avoid any interaction between the tool or the tool holder and the pipe (4), the carriage (6) is initially displaced on the rolling bridge in order to separate the tree (9), and therefore the modules pipe tool holder (4), and a then the rotation of the tool considered is carried out taking care before getting the car tool holder (25) to the maximum of your career on the stiffening mast (23), described below more in detail. When the rotation of said tool is over, the carriage (6) is brought back to its original position.

Finally, figure 3c, once the collecting the pieces of scab, the shovel is displaced on the chopper tool and starter tool, which comprises for example three identical tools themselves, suffers from turn a rotation of 270º, and then, previous displacement of the carriage (6) to allow the movement of said tools

Thus, the great simplicity of use is conceived of the installation according to the invention.

The modules will now be described in more detail tool holders used within this installation, and this in connection with figures 4 to 11.

According to a fundamental characteristics of the invention, each of the modules tool holder, in particular the modules of anode change, comprise two activation systems independent. They comprise in principle a cable system (13), rolled on one or two drums (14), the latter being moved in rotation by means of an electric motor (15), by means of a wheel reducer (16) and worm screw (17), each being wheel (16) solidarity and coaxial with one of the drums (14) and starting to cooperate with the screw (17) collinear with the motor shaft of the engine (15). These drums are positioned at the level of upper chassis of each of the modules.

The wire (13) is rolled over two constitutive pulleys of a hoist (18) and trace in the direction of a fixed point (19).

The load, and in particular the tool holder considered, is set at level of the hoist by any appropriate means, this being in turn in solidarity with a car (25), as described in more detail in continuation.

According to the invention, the fixed point (19) is at its once in solidarity with the end of the screw (20) of a cat mechanical (21), driven by an electric motor (22).

Thus, this double lifting system allows perform a classic lift that ensures the race of displacement of the anodes over relatively distances important at a relatively high speed for a load reduced, and a lift with plucking, capable of developing an important effort in a reduced race with a speed limited

This device allows for its ability to traction, on the one hand ensure the development of effort necessary for the tearing of the spent anode, intended to be replaced, but on the other hand, considering the low corresponding speed, facilitates the placement of the new anode at the level of the tank.

The organs of the kinematic chain, and in particularly wheels (16), drums (14) and cables (13), are sized according to the intense effort exerted by said second body, and to which they are subjected, taking into account Your request during the start-up phase.

Moreover, the choice of a reducer of wheel and screw (16, 17) at the high speed motor level which ensures the rotation of the drums (14), allows, using the low indirect performance between the reducer and the drum, decrease the size of the brakes at the level of the engine shaft of said motor (15), necessary when it is in the starting phase, and by so much more generally the volume.

Advantageously, it is provided to each of the two drum tool holder modules (14) synchronized by conception of the reducer, which each receive two cables (13), so that the total number of cables is four, as shown in particular in figures 10 and 11, by example. In this way, it is possible to reduce the size of the pulleys, drums as well as that of reducers, and so more generally, decrease the volume of the device.

According to an advantageous feature of the invention, the tool holder modules are associated of change of anodes three by three, as represented in the Figures 8 and 9. This configuration is intended to allow Simultaneous change of three worn anodes. It is understood without However, each module is capable of functioning independently of each other, so that, despite the use of a system with three modules, one or even two of they can only be activated for the change of anodes.

The separation between the three modules tool holder corresponds to the distance between anode shafts This separation is likely to be different. according to the installation in question and is therefore adjustable. This determined by connecting rods, whose length corresponds to said distance between axis. This provision allows the adaptation of system to any type of installation.

As can be seen in figures 7 to 9, a each tool holder module is associated with a guide mast vertical (23), supported at the level of the upper chassis of the module by means of a prestressing device that incorporates kneecaps, thus capable of allowing a certain degree of freedom to bottom level (24) of the mast. This mast (23) is intended to allow guidance, in particular of a car (25) that contains the hoist (18) and by extension of the suspension zone of the load, this carriage (25) being provided with rollers (26) which they rest on both sides of said mast (23). This mast is semirigid. The prestress regulation threshold is such that avoid in particular the risks of angular displacement of said tool holder, in particular at the end of career, in case of limited efforts, and in particular inherent in the intense magnetic field that reigns in the installation, and to which the metallic elements are therefore subjected constituting a large part of the elements that enter the constitution of the module.

According to another feature of the invention, each module comprises a cable loosening system, allowing thus limit the vertical displacement of the tool when interacts with an obstacle, such as when The shovel touches the bottom of the tank. In the latter case, it is desired limit this risk to the maximum, taking into account the relative Cuba fragility. Moreover, the cable loosening allows to keep the cable turns perfectly tidy on the drums (14).

This cable loosening is described more particularly in connection with figures 10 and 11. Its realization is obtained by solidarity in a non-fixed way, the hoist (18) with the carriage (25) of displacement of the tool holder on the mast (23) by means of a set of two connecting rods (27, 28), capable of moving according to a deformable parallelogram, and articulated respectively on the frame (29) at which the hoist is mounted, and on said carriage (25), between two extreme positions, corresponding to the cable loosening absorption stroke represented by the double arrow A in figure 10.

Thus, figure 10 represents the carriage (25) supported by an object or a surrounding obstacle, no longer being the frame (29) in contact with said carriage (25). One sensor (no shown), positioned between the carriage (25) and the frame (29) will have given the stop engine order while made a downward movement. The maximum stopping distance of the mobile hoist is represented by the double arrow A.

Figure 11 represents the suspended carriage (25) without contact with the environment, being the frame (29) that supports the pulley pulleys in contact with the carriage (25).

Advantageously, a spring can be placed between the upper face of the frame (29) and the carriage (25), in order to decrease the apparent weight of said car on an object surrounding, which allows in this hypothesis, to preserve the Cuba of Electrolysis and its surroundings.

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The tool holder module according to the invention is sized to accept about loading efforts close to 10 tons for speeds of the order of one millimeter per second. In return, for speeds of the order of 15 meters per minute and more runs important, the effort to displacement is of the order of two tons.

The use of these modules, activated by electric way, it is totally suitable for installations of existing electrolysis aluminum production, to the extent in which, in particular, by the physical separation of functions associated with different loads, it allows to limit the Roller reactions on the raceways of the existing buildings, and therefore, do not need any civil engineering extension, while allowing increase significantly the security conditions.

Claims (15)

1. Tool holder module intended to be used within an installation of lifting, which comprises two motorized lifting elements of independent way:

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a first organ, constituted by a lifting system comprising at least one cable (13), one or two motorized drums (14) electrically, a hoist (18) at the level of which a tool holder, said or said winding cables (13) on said or said drum (s) (14), and being Forwarded (s) at the hoist level (18), said first lifting body designed to ensure displacement of a load at the level of the hoist (18) at relatively high speed important, and according to an extensive career;

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one second organ, of which one of the constituent elements is in solidarity with the end of the cable (13) of said first organ after forwarding at the hoist level (18), and that includes some means that allow to ensure in cooperation with said hoist the vertical displacement at reduced speed and according to a limited run of a more important load.

2. Tool-holder module according to claim 1, intended for the removal of spent anodes in an electrolysis aluminum production facility and the transfer of said anodes and new anodes replace the latter, characterized in that:

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the first organ is intended to ensure the displacement of an anode to relatively important speed and according to a career extensive;

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the second organ is intended to ensure the removal of said anode according to a reduced speed and for a limited run.

3. Tool holder module according to one of claims 1 and 2, characterized in that said second member is constituted by a mechanical or electromechanical jack (20, 21), at the end of which the cable (13) of said said first organ, and destined to exert intense or tearing effort. 4. Tool holder module according to one of claims 1 to 3, characterized in that it is provided with a cable loosening, intended to limit the load applied by the tool, of which said module is provided, over an obstacle, and in particular at the bottom of an electrolysis tank. 5. Tool holder module according to one of claims 1 to 4, characterized in that it comprises a semi-rigid vertical guide mast (23), in solidarity with the chassis of said module, and along which a carriage (25) is capable of sliding at which level the tool holder itself is in solidarity. 6. Tool holder module according to claim 5, characterized in that the guide mast (23) is secured at the level of the module chassis by means of a prestressing device, intended to allow a certain degree of freedom at the bottom level (24) of the mast. 7. Tool holder module according to one of claims 1 to 6, characterized in that the motorization of the drums (14) is ensured by at least one electric motor (15), coupled to the drums (14) by means of a reducer wheel (16) and screw (17), each wheel (16) being integral and coaxial with one of the drums (14) and cooperating with the screw (17) collinear with the motor drive shaft (15). 8. Tool-holder module according to claim 7, characterized in that the elements of the kinematic chain, and in particular the wheels (16), the drums (14) and the cables (13), are sized according to the intense effort exerted by said second organ (20, 21), and to which they are subjected, taking into account their request during the start-up phase. 9. Installation for the exchange of spent anodes inside an aluminum electrolysis production factory, which comprises a rolling bridge (5) capable of moving over the electrolysis tanks (1), and on which a carriage (6) provided with a tool-holder module according to any of claims 2 to 8 is moved according to a direction perpendicular to the bridge, characterized in that the carriage (6) comprises a vertical shaft (9) that receives a plurality of coaxial crowns (10, 11, 12), capable of being rotated independently of each other, each of said crowns receiving one or more tool-holder modules, respectively intended:

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to allow break the superficial crust that is created on the upper surface of the electrolysis bath of each one of the tanks;

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to pick up all or part of the pieces that come from the breakage of said crust;

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and to extract and transfer the spent anodes out of the vats and lead to level of these vats new anodes,

said modules being tool holders, and consequently, the tools that support capable of describing some portions of circle arc. 10. Installation for changing worn anodes according to claim 9, characterized in that the carriage (6) is crowned by a platform (8), intended to receive an upper cabin, in turn intended to receive the user, the latter being able to receive to activate the corresponding tools and tool holders in it, while monitoring the maneuver. 11. Installation for the replacement of worn anodes according to claim 10, characterized in that the maximum value of the angle that separates two extreme tools or tool holders is less than the volume generated by the cabin. 12. Installation for exchanging worn anodes according to claim 9, characterized in that the angle separating two extreme tools or tool holders is less than 180 °. 13. Installation for changing worn anodes according to one of claims 9 to 12, characterized in that each of the axial crowns (10-12) has an extension, located substantially in the same plane, and at the level of which it is fixed one or more toolholder modules (13, 14, 15). 14. Installation for the exchange of spent anodes according to one of claims 9 to 13, characterized in that one of the crowns (10) has a plurality of tool-holder modules, mounted parallel to each other, and capable of operating independently. of the others. 15. Installation for changing worn anodes according to claim 14, characterized in that the separation between the toolholder modules is adjustable and corresponds to the distance between axes of the anodes, said separation being determined by connecting rods, the length of which corresponds to said wheelbase.