Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
  • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
  • C25C3/12—Anodes
  • C25C3/125—Anodes based on carbon
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
  • C25C3/22—Collecting emitted gases

Definitions

• the present invention belongs to the field of the production of aluminum by igneous electrolysis, and relates more particularly to a confinement device for an anode assembly.
• anodes traditionally made of carbonaceous material, are immersed in these tanks, each of the said anodes being provided with a metal rod which is therefore electrically conductive, intended for its electrical and mechanical connection to an anode frame which is mobile with respect to a fixed gantry. above the electrolytic cells.
• the assembly consisting of the rod and the anode made of carbonaceous material attached to its end, is referred to as the anode assembly.
• the anode assembly considered is detached from the anode frame, then evacuated to a storage location at which the anode cools before being either reprocessed, in order to recover the carbonaceous material not consumed, or pier.
• Also proposed in document WO 2012/156616 is a device similar to that previously described, comprising a container containing non-fluidized alumina in sufficient quantity to cover the anode butt, and provided with a device capable of ensuring then the fluidization of the alumina. Again, this device is complex to implement, due to the presence of alumina, in addition to the device ensuring its fluidization.
• document WO 2016/103020 has proposed a containment system for at least one anode assembly, comprising a support capable of receiving said anode assembly, said support defining with side walls a receiving enclosure, and a rigid cap , adapted to be received at the upper end of the side walls defining said receiving enclosure, and to cover the entire stem of the anode assembly.
• the device thus described makes it possible to achieve satisfactory confinement of the anode assembly, on the other hand, it generates, due to the very reason of the need to cover the anode assembly, that is to say rod and anode, a bulk important, heavy, and whose handling typically involves the implementation of MSE (service machines electrolysis), susceptible as a result, due to their relatively limited number in an aluminum production plant, their neutralization affecting other tasks.
• MSE service machines electrolysis
• the civil engineering likely to allow the implementation of such a device must be adapted because of the height necessary for its manipulation, since as well, it is necessary to take into account the height of the anode assembly in as such, plus the height of the rigid cap, in order to allow its positioning above said anode assembly.
• the costs associated with such an adaptation of civil engineering are quite simply incompatible with the rational management of an aluminum production facility.
• the invention aims to overcome these drawbacks, and in particular to reduce both the size and the weight of such a device for containing an anode assembly, and to facilitate its handling and the associated logistics.
• this confinement device for at least one anode assembly said assembly comprising a spent anode fixed to a metal rod, comprises:
• a receptacle for receiving the anode assembly, said anode assembly resting within said receptacle via the lower surface of the spent anode;
• ⁇ a bell open at its lower end, and adapted to form a closed volume in cooperation with said receptacle, within which is received said at least one anode assembly.
• the bell is likely to take two forms:
• the invention consists in implementing a bell, for example flexible or flexible, capable of being deployed between a non-operational storage position and a deployed operational position.
• the device of the invention is easier to handle and to store, consequently making it possible to avoid necessarily having recourse to electrolysis bridges or MSEs, and in addition, to be able to be implemented within existing installations, without causing any modification of the civil engineering.
• the bell has a symmetry of rotation, even of revolution, which appears in particular when said bell is in the operational position, that is to say deployed.
• the bell is made of flexible material, provided at its periphery with rigid arches oriented along planes substantially parallel to each other, and perpendicular to the axis of revolution of the bell, distributed more or less regular according to all or part of the height of said bell.
• the flexible material is advantageously a refractory material, due to the high temperature of the anode at the vessel outlet. It is indeed recalled that the typical temperature of the anode at the outlet of the tank is close to 1000°C.
• This material can, for example, be chosen from the group comprising ceramic fabrics and/or fabrics based on basalt and/or glass fibers.
• This fabric regardless of the material that composes it, can also be coated or coated with one or more layers of a protective material, such as silicone or PTFE (polytetrafluoroethylene), providing the functions of sealing and protection against attacks inherent to HF.
• the bell comprises, in its lower part, a rigid cover or base, capable of being fitted onto the receiving receptacle of the anode assembly, and a rigid plate, in particular metallic , connected by means of a flexible zone or skirt to the upper peripheral edge of said cover, said rigid plate being pierced with through holes communicating with the flexible or flexible part of the bell.
• the upper part of the flexible zone of the bell is also provided with a rigid plate, in particular metallic, called the upper rigid plate, capable of resting at the level of the upper end of the anode rod.
• the upper bell comprises at its base a rigid plate, in particular metallic, the dimensions of which correspond to the upper surface of the receptacle for receiving the anode assembly, so as to come to rest on the upper end of said receptacle, said rigid plate being pierced with through holes able to communicate with the flexible part of the bell.
• said rigid plate is provided with means for storing the flexible zone of the bell in the non-operational position.
• these storage means consist of walls, in particular metal, emanating from the upper face of said rigid plate essentially perpendicular thereto, capable of favoring the storage of the flexible zone of the bell in non-operational mode. Their respective spacing is chosen so as to facilitate said storage without altering the deployment of said flexible zone of the bell.
• said rigid plate and generally the bell itself, is provided with means for receiving or cooperating with members for gripping and manipulating said bell.
• these reception or cooperation means may consist of zones for receiving the forks of a forklift, or even lifting rings capable of cooperating with lifting means mounted on a self-propelled crane, or even on the MSE , or even on a portal dedicated to this purpose.
• the objective is to facilitate handling of the entire device, in particular when the latter receives one or more anode assemblies.
• FIG. 1 is a schematic cross-sectional representation of a conventional electrolysis cell.
• FIG. 2 is a schematic sectional representation of the principle of the anode assembly confinement device according to the invention.
• Figure 3 is a schematic representation in perspective illustrating a first embodiment of the invention, with the containment device in operational mode.
• Figure 4 is a view similar to Figure 3 seen from above.
• Figure 5 is a view similar to Figure 3 in side view.
• Figure 6 is a schematic sectional view along line VI -VI of Figure 5.
• Figure 7 is a schematic perspective view of the containment device of Figure 3 in non-operational mode.
• Figure 8 is a schematic perspective view of a second embodiment of the containment device of the invention.
• Figure 9 is a more detailed schematic view of the device of Figure 8.
• Figure 10 is a schematic perspective view of the device of Figures 8 and 9 in non-operational mode.
• Figure 11 is a schematic perspective view of a third embodiment of the containment device of the invention.
• Figure 12 is a more detailed schematic view of the device of Figure 11.
• Figure 13 is a schematic perspective view of the device of Figures 11 and 12 in non-operational mode.
• FIG. 1 Schematically shown in Figure 1 is a sectional view of an electrolytic cell (1) of conventional construction.
• this tank (1) comprises a metal box (2), receiving refractory materials (3) and (4), a cathode assembly (5) secured to a metal bar (6) to which the electrical conductors (7 , 8) intended to carry the electrolysis electric current.
• the cathode assembly (5) is covered with a bath of liquid aluminum (9) resulting from the electrolysis reaction, surmounted a liquid bath (10) of alumina and molten cryolite, itself covered with a cover (11) based on solid bath and alumina.
• the rods (13) are mechanically fixed and electrically connected to a supporting structure (15).
• Reference (16) represents the device for supplying the tank in question with alumina and/or A1F3.
• the reference (17) represents the removable cover(s), typically metallic, intended to confine the effluents resulting from the electrolysis reaction, then direct them to an effluent treatment center.
• the anodes (12) are made of prebaked carbonaceous material. They are gradually consumed during the electrolytic reduction reaction of the aluminum and the worn anodes (12') must therefore be replaced by new anodes (12).
• anode (12) When the anode (12) is consumed (anode (12') on the right in figure 1), it should be replaced with a new anode.
• the anode assembly (12', 13, 14) is therefore extracted from the tank with, in addition, pieces of bath cover (11) forming a crust remaining attached to said spent anode (12'). Fluorinated gases are emitted by the anode thus extracted, in quantity all the more important as the temperature of the anode is high, typically close to 1000°C.
• FIG. 2 has been illustrated a receptacle (20), typically metallic, capable of receiving the anode assembly (12', 13) and more particularly the anode proper (12').
• This receptacle is then closed by means of a bell (21), the base (22) of which is received at the level of the upper edge (23) of the said receptacle (20), and the upper end of which bears on the end superior (18) of the rod (13).
• an internal volume (27) formed by the receptacle is defined
• said bell (21) has in the deployed position, that is to say in operational mode, a shape in this case pyramidal, or even conical, the base of said bell (21) being adapted by simple deposit on the upper edge of a receptacle (20).
• said receptacle (20) is capable of receiving six anode assemblies positioned two by two, as can clearly be seen in Figures 3 and 4.
• the bell (21) is configured to simultaneously cover two anode assemblies received within said receptacle (20).
• this bell (21) is likely to be in two forms, respectively an extended form (figures 3, 4, 5 and 6), and a folded form (figure 7).
• Said bell (21) comprises a flexible peripheral casing (24), typically made of a fabric based on ceramics, basalt or even glass fibers, advantageously coated with silicone or PTFE.
• this flexible envelope (24) is in deployed mode in the form of alternating folds. Due to the pyramidal or conical shape of the bell, these folds have larger dimensions at the base than at its upper end, said folds being capable, as illustrated in FIG. 7, of folding over one another. others, and thus considerably reduce the size of the bell (21) when it is not in the operational position.
• rigid hoops (25) are joined together, for example by bolting, at the level of the corresponding folds.
• the base of the bell is provided with means, in this case consisting of sheaths (28), capable of allowing the insertion within them of the forks of a forklift .
• the bell (21) comprises a base (30) intended to be received on the upper rim of the receptacle (20).
• This base (30) in this case made of metal, has a generally parallelepiped shape, and is associated by means of a flexible skirt (31) with a rigid metal plate (32), the surface of which is of dimension less than that of the surface defined by a cross section of the base (30).
• This metal plate (32) is pierced, in the example described, with two through holes, intended to allow the passage at this level of the anode rods (13), as can be seen for example in Figure 8.
• a flexible zone (33) is capable of being deployed in the operational position from these through-holes, as can be seen in FIGS. 8 and 9.
• the upper end of said flexible zone (33) receives a rigid upper closing plate (34), for example metallic, intended to bear on the upper end (18) of the anode rods (13).
• FIGS 11, 12 and 13 illustrate a third embodiment of the invention.
• the receptacle (20) is surmounted by a riser (40) whose upper edge is inscribed in a plane located above the upper surface of the tripods (14).
• This riser (40) is secured, for example following a welding operation, to said receptacle (20).
• the flexible bell as such consists, for its part, of a rigid metal plate (41), similar to the metal plate (32) of the previous embodiment, dimensioned in such a way as to be received in a sealed or substantially sealed manner. on the upper edge (42) of the socket (40).
• the flexible zone (43) of said bell is substantially similar to that described in relation to the second embodiment.
• said flexible zone (43) is received within means (45) suitable for storing it, the means being constituted by metal plates erected perpendicularly from the upper surface of the rigid metal plate (41).
• said metal plate (41) is pierced with through holes, in order to allow the passage of the anode rods (13) through said plate, and thus allow the positioning of the bell above and around said rods anode until defining the desired confinement volume (27).
• the upper plate (41) is also provided with means defining sleeves (46), allowing the insertion within them of the forks of a forklift, and de facto facilitating the handling of said bell.
• the metal/metal contact at the base of the bell can be optimized by increasing the covering surface of the base of the bell on the receptacle or on the riser, or even by providing a groove for receiving said base at the vicinity of the peripheral edge of the receptacle or the riser.
• a seal for example made of silicone.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electrolytic Production Of Metals (AREA)
• Primary Cells (AREA)
• Microwave Tubes (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=77317065

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Family Cites Families (6)

• 2021
  • 2021-05-06 FR FR2104782A patent/FR3122777B1/fr active Active
• 2022
  • 2022-04-27 WO PCT/FR2022/050796 patent/WO2022234215A1/fr active Application Filing
  • 2022-04-27 CA CA3209815A patent/CA3209815A1/fr active Pending
  • 2022-04-27 EP EP22724233.6A patent/EP4334510A1/de active Pending

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