WO2019162817A1 - Cellule électrolytique dotée d'une superstructure ayant des pattes intermédiaires, appropriée pour le procédé hall-héroult - Google Patents

Cellule électrolytique dotée d'une superstructure ayant des pattes intermédiaires, appropriée pour le procédé hall-héroult Download PDF

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Publication number
WO2019162817A1
WO2019162817A1 PCT/IB2019/051308 IB2019051308W WO2019162817A1 WO 2019162817 A1 WO2019162817 A1 WO 2019162817A1 IB 2019051308 W IB2019051308 W IB 2019051308W WO 2019162817 A1 WO2019162817 A1 WO 2019162817A1
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WO
WIPO (PCT)
Prior art keywords
superstructure
rest
support members
cathode
anode
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PCT/IB2019/051308
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English (en)
Inventor
Kasim BASHA
Alexander MUKHANOV
Mahmood ALAWADHI
Pragneshkumar CHAUHAN
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Dubai Aluminium Pjsc
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Publication of WO2019162817A1 publication Critical patent/WO2019162817A1/fr

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    • 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
    • C25C3/10—External supporting frames or structures
    • 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
    • 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
    • C25C3/16—Electric current supply devices, e.g. bus bars

Definitions

  • the invention relates to the field of fused salt electrolysis, and more precisely to electrolytic cells suitable for the Hall-Heroult process.
  • the invention relates to a superstructure for a Hall-Heroult cell operating at very high amperage. Such cells can be very long, which raises issues related to the mechanical strength of the superstructure.
  • the Hall-Heroult process is the only continuous industrial process for producing metallic aluminium from aluminium oxide.
  • Aluminium oxide (AI2O3) is dissolved in molten cryolite (Na3AIF 6 ), and the resulting mixture (typically at a temperature comprised between 940 °C and 970 °C) acts as a liquid electrolyte in an electrolytic cell.
  • An electrolytic cell used for the Hall-Heroult process typically comprises a steel shell (so-called “potshell”), a lining (comprising refractory bricks protecting said steel potshell against heat, and cathode blocks usually made from graphite, anthracite or a mixture of both), a superstructure and a plurality of anodes (usually made from carbon) that plunge into the liquid electrolyte.
  • Anodes and cathodes are connected to external busbars.
  • An electrical current is passed through the cell (typically at a voltage between 3.5 V and 5 V) which electrochemically reduces the aluminium oxide, split by the electrolyte into aluminium and oxygen ions, into aluminium at the cathode and oxygen at the anode; said oxygen reacting with the carbon of the anode to form carbon dioxide.
  • the resulting metallic aluminium is not miscible with the liquid electrolyte, has a higher density than the liquid electrolyte and will thus accumulate as a liquid metal pad on the cathode surface from where it needs to be removed from time to time, usually by suction into a crucible.
  • Industrial electrolytic cells used for the Hall-Heroult process are generally rectangular in shape and connected electrically in series, the ends of the series being connected to the positive and negative poles of an electrical rectification and control substation.
  • the general outline of these cells is known to a person skilled in the art and will not be repeated here in detail. They have a length usually comprised between 8 and 25 meters and a width usually comprised between 3 and 5 meters.
  • the cells are always operated in series of several tens (up to more than a hundred) pots (such a series being also called a “potline”); within each series DC currents flow from one cell to the neighbouring cell.
  • the cells are arranged in a building, with the cells arranged in rows either side- by-side, that is to say that the long side of each cell is perpendicular to the axis of the series, or end-to-end, that is to say that the long side of each cell is parallel to the axis of the series. It is customary to designate the sides for side-by-side cells (or ends for end-to end cells) of the cells by the terms“upstream” and“downstream” with reference to the current orientation in the series. The current enters the upstream and exits downstream of the cell.
  • the electrical currents in most modern electrolytic cells using the Hall-Heroult process exceed 200 kA and can reach 400 kA, 450 kA or even more; in these potlines the pots are arranged side by side. Most newly installed pots operate at a current comprised between about 350 kA and 600 kA, and more often in the order of 400 kA to 500 kA.
  • the DX+ cell by Dubai Aluminium operates at 460 kA and has a length of about 14.3 meters.
  • the superstructure of a Hall-Heroult cell is formed by one or more horizontal beams made of steel, the ends of which are supported upon legs, and which supports various devices and components arranged above the potshell.
  • the superstructure supports the anode busbar (so-called anode beam) to which are clamped the anode rods of the anode assemblies (said anode assemblies comprising the anode rod and the carbonaceous anode, the anode rod being fixed to the anode by means of the anode yoke welded to the anode rod that extends into the anode), the alumina feeding system (comprising a dedicated distribution system with its reservoir, and a plurality of protruding point-like tools called“crust breakers”), and ducts for collecting effluents, gas and dust emitted by the cell.
  • the anode beam is connected to the anodic current risers, part of the mass of which is also supported by the superstructure; the anode beam is
  • the superstructure can be represented by a fixed beam (i.e. a beam supported on both ends) that needs to resist a certain load.
  • a fixed beam i.e. a beam supported on both ends
  • the load increases because the superstructure will carry a larger number of anodes (the unitary mass of which being of the order of a metric ton), and temperature effects on beam deflection will increase.
  • beam deflection may become significant, and even if structurally safe, may require individual corrections of the anode height, at least for those anodes that are close the beam center.
  • the load carried by the beam is not constant, as anodes burn off and need to be replaced regularly.
  • beam deflection not only depends on temperature but also on the mass of the anodes, especially in the center of the cell. Uncontrolled beam deflection is not compatible with the requirement of a precise anode height control.
  • the anode-cathode distance or more precisely, the interpolar distance (vertical spacing) between the anode and the subjacent electrolyte- metal interface (knowing that the liquid metal is denser than the electrolyte and forms a pad on the top of the cathode) is a critical parameter for the control of an electrolytic Hall- Heroult cell. It is usually comprised between 2 cm and 5 cm. As the anodes burn off during the electrolysis process, the ACD is not constant and needs to be adjusted regularly.
  • the superstructure must also withstand exceptional forces that arise in certain situations, for example during crust breaking prior to alumina feeding (when the mechanical resistance of the crust must be broken by the crust-breakers) and during vertical displacement of the anode beam (when one or more anodes are frozen in the crust and need to be torn out of or pushed into the crust). And finally, the superstructure should take up the least possible amount of ground space, and causing minimum obstruction.
  • an increase in beam section could solve the problems related to the increase of the length of the cell and the mass of its superstructure.
  • this will render the superstructure bulky and expensive, and will increase the total height of the cell.
  • This in turn, will require a higher building, which adds to the capital cost of the plant.
  • increasing the height of the cell (including its superstructure) by 1 dm will require the internal height of the building to be increased by about 3 dm; such increase should be minimized.
  • EP 0 210 1 1 1 (Aluminium Pechiney) describes a cell with a superstructure provided with two intermediate legs on each long side of the cell, resting on the upper rim of the potshell.
  • EP 0 584 024 (Aluminium Pechiney) teaches that superstructures with end support and intermediate legs such as those disclosed in EP 0 210 1 1 1 are not advantageous for very large cells because the obstruction of the cells is unpractical for performing certain maintenance operations, and presents a risk of accidents. This document therefore recommends a superstructure which has no more end supports.
  • Early published pictures of the AP 50 cell showed indeed four legs on each long side of the cell and no support at the end of the cell.
  • the present invention aims at providing a stable superstructure suitable for very long electrolytic Hall-Heroult cells, that solves at least in part the shortcomings of prior art.
  • a length exceeding 20 meters is targeted (in particular a length of about 22 meters for a cell operating with a current of the order of 700 kA).
  • Such a superstructure represents an enormous mass that can no longer be reasonably constructed as a fixed beam supported on both ends only: intermediate supports are necessary.
  • intermediate supports are necessary.
  • thermal expansion of the superstructure should not modify the ACD, and the whole system should be as simple as possible.
  • the superstructure absorbs all deflections developed due to physical loads, thermal stresses and thermal expansions.
  • the combination of all the above deformations are absorbed by suitably designed central leg(s) which floats laterally and/or vertically during thermal stresses and physical loads and slides in horizontal and/or vertical plane(s) during thermal expansions.
  • the superstructure comprises a single longitudinal central structural element supported by a plurality of support members, such as pillars, columns or legs (said support members being referred to in the following also as“legs”), comprising a first group of support members (referred to as“first support members” or“end support members”) that are provided at each end of the potshell, and a second group of support members (referred to as“second support members” or“central support members”) provided at each long side of the potshell.
  • first support members referred to as“first support members” or“end support members”
  • second support members “central support members”
  • Said end support members can be supported, directly or indirectly, by the upper rim of the potshell, or they can rest upon the nearby floor, usually made of concrete; both variants are known as such.“Indirectly supported” by the ground or the upper rim of the potshell means here: being supported by a structural element (called here“base element”) that is directly supported by the ground or the upper rim (not taking into account the presence of pads for electrical insulation).
  • end support members rest on the rim of the potshell, a suitable electrical insulation that is both efficient and heat-resistant must be provided between the rim and the leg; mica board can be used in a known way. If the end support members rest, directly or indirectly, on the ground, epoxy pads can be used as electrical insulators between the leg and the concrete ground or between the leg and the base element.
  • Said second support members are provided with legs which are supported, directly or indirectly, by the concrete floor.
  • Appropriate insulation pads must be used, which is known as such to a person skilled in the art.
  • the present inventors have found that as the potshell naturally tends to“open” during heating, it is not desirable to add any significant load onto the rim of the long side of the potshell; the importance of this problem becomes more acute as the length of the cell increases.
  • the legs of the central support members should not rest on the upper rim of the potshell, unless said upper rim (and possibly the potshell as such) is specifically reinforced in order to be able to bear this additional, localized load.
  • each of the legs of the central support members rests on a dedicated base element, which can be a steel column which rests on the concrete floor.
  • the number of support members of the second group is two, that is to say one on each long side of the cell, arranged in the center or close to the center of the long side. This minimizes the impact of the legs on accessibility of the pot from its long side.
  • Said single longitudinal central structural element can be a welded assembly of steel plates and/or steel profiles. It is designed so as to extend over the whole length of the superstructure; this is the preferred embodiment. Whatever its construction and structure, from the viewpoint of the mechanics of materials said single longitudinal central structural element can be represented as a single beam, and for this reason it will also be called here the“superstructure beam”.
  • said central support members are fixed at the upper part of the superstructure beam.
  • said central support member can be a gantry that surrounds the section of the superstructure and that has a welded connection to its upper portion.
  • the superstructure can rest on the top of the gantry, which has then a welding connection to its lower portion.
  • the design of the superstructure takes advantage of the elasticity of the superstructure beam, in the sense that under normal operating conditions of the electrolysis cell said superstructure beam is pre-stressed.
  • said central support members are designed as floating support members, which means that they are not fixed on the surface on which they rest (be it the ground or the upper surface of the base element): they can move laterally and/or vertically with respect to said surface.
  • Said end support members are not floating but fixed on the ground or the upper rim of the potshell.
  • a first object of the invention is a superstructure for an electrolytic cell, suitable for the Hall-Heroult electrolysis process, said superstructure comprising a frame of substantially rectangular shape, said frame comprising: at least one so called longitudinal beam; said frame further compsising first support members, or end support members, provided at opposite longitudinal ends of said beam; said frame further comprising second support members, or intermediate support members, provided at an intermediate longitudinal location between said ends of said beam; said superstructure being characterized in that it comprises a so called floating part, which is motionless with respect to said beam at least along one direction amongst vertical direction and horizontal direction but which is moveable in operation with respect to the ground at least along one direction amongst vertical direction and horizontal direction, said floating part comprising abutment means, said abutment means being able to cooperate with rest means fixed with respect to the ground.
  • Said floating part can belong to said intermediate support members or to said beam.
  • Said intermediate support members comprise two legs, provided on either side of said elongated beam, each leg comprising
  • said superstructure can comprise at least one gantry, said gantry comprising a central body and two lateral legs; said body of said gantry is attached to elongated beam and at least part of each lateral leg of said gantry forms said floating part.
  • Said gantry is attached to the ground, said rest means and said abutment being formed by facing faces of said gantry and said elongated beam.
  • Said rest means can be formed by the ground itself.
  • said abutment means can comprise a lower free end of said floating part, whereas said rest means comprise an upper free end of said rest part.
  • Said lower free end of said floating part and said upper free end of said rest part can be provided with means for facilitating mutual sliding of facing lower and upper free end.
  • said means may comprise plates, the surface of which is larger than that of rest and floating parts.
  • Case 1 The superstructure beam has been mounted and put in place, with all equipment in place including the anodic current risers but excluding the anode assemblies.
  • the superstructure beam rests on the end support members and on the central support members.
  • the length of the central support members is chosen such that the superstructure beam is allowed to sag, that is to say: exhibits a concave downward deflection.
  • This deflection should not exceed a value of xi mm per meter of length, xi being preferably 1 , more preferably 0.9, and still more preferably 0.85.
  • the downward deflection does not exceed 20 mm without considering thermal stresses (as this is a downward deflection this will be noted here with a negative sign 20 mm”). This downward deflection is considered as pre-stressing the structure (cambering the structure).
  • the superstructure beam being supported by the central support members, its loading with the anode assemblies (which can represent a very significant mass, of the order of 1 to 2 metric tons per assembly) should not increase the deflection.
  • Case 2 Start-up of the cell, with all anodes in place and a cell temperature that is higher than the normal operating temperature of the pot.
  • the heat generated by the pot will cause thermal stresses experiencing very large deflections (free deflection) if not supported at center which is now limited, for example to -20mm (restricted deflection).
  • the superstructure beam will experience a convex upward deflection due to the upward stress caused by the difference of free deflection to restricted deflection. This will allow the superstructure to lift upwards causing release of pre-stress (camber) and the upward deflection will reach to 0 mm (as this is an upward deflection it will be noted here with a positive sign, for example as“+ 20 mm”).
  • the central support legs preferably still rest on the surface but experiences upward stress as explained above.
  • the superstructure should be designed such that the deflection in this case does not exceed X 2 mm per meter of length. In an advantageous embodiment, for a 24 m long superstructure beam the deflection is limited to designed value.
  • Case 3 Normal operation of the cell, at a temperature that is smaller than the start-up temperature.
  • the superstructure should be designed such that the superstructure beam has a concave downward deflection (stress) to an acceptable or designed value expressed here by X 3 , defined in the same way as X 2 . In an advantageous embodiment this deflection is X 3 about X2/2.
  • the legs of the central support members will usually be in contact with the surface on which they rest as in Case 1.
  • floating parts of superstructure may move vertically with respect to rest parts of superstructure, which are fixed to the ground.
  • said vertical motion is not a normal functional motion of said superstructure.
  • another object of the present invention is a method of mounting a superstructure for an electrolytic cell, suitable for the Hall-Heroult electrolysis process, said superstructure comprising a frame of substantially rectangular shape, said frame comprising at least one longitudinal beam, first support members, or end support members, provided at opposite longitudinal ends of said beam and second support members, or intermediate support members, provided at an intermediate longitudinal location between said ends of said beam, said cell further comprising: a cathode forming the bottom of said electrolytic cell and comprising a plurality of parallel cathode blocks, each cathode block comprising at least one metallic cathode collector bar protruding out of each of the two ends of the cathode block; said cell further comprising a lateral lining defining together with the cathode a volume containing the liquid electrolyte and the liquid metal resulting from the Hall-Heroult electrolysis process; said cell further comprising an outer metallic potshell containing said cathode and lateral lining; said cell further comprising
  • Said method of mounting said superstructure comprises the steps of : (i) providing said superstructure with a so called floating part, which is motionless with respect to said beam at least along one direction amongst vertical direction and horizontal direction but which is moveable in operation with respect to the ground, said floating part comprising abutment means; (ii) at a first temperature, which is inferior to normal operation temperature of the cell, making said abutment means abut against rest means fixed with respect to the ground, said superstructure being not provided with said anodes and anode rods; (iii) attaching said anode rods and said anodes on the superstructure; (iv) heating said cell up to a second temperature, superior to normal operation temperature of the cell, so that said elongated beam undergoes a first deformation and abutment moves with respect to rest means, according to a first movement.
  • said first deformation is an upwards deformation
  • abutment means moves away from rest means according to said first movement along a vertical direction, so that abutment means is not in contact any more with rest means, a first gap (X2) being created between facing faces of abutment means and rest means.
  • Said method can further comprise the step of operating the cell at a temperature between said first and second temperatures, so that said elongated beam undergoes a further deformation (f4) so that abutment means further moves with respect to rest means, according to a further movement.
  • Said further deformation can be a downwards deformation, and abutment means moves closer to rest means according to said further movement along a vertical direction, abutment means being still out of contact with rest means, a second gap (X3) being created between facing faces of abutment means and rest means, the value of second gap being inferior to that of first gap (X2) .
  • Said method can further comprise the step of placing shims or wedges between facing faces of abutment means and rest means, so as to ensure electrical connection between said abutment means and said rest means.
  • FIGS 1 to 9 represent various embodiments of the present invention.
  • Figure 1 shows a schematic perspective view of an electrolytic cell with a superstructure beam having intermediate members or legs, according to the invention, said cell being in a first position of its mounting process.
  • Figure 2 shows a schematic side view of the cell depicted on figure 1 , in a first position of its mounting process.
  • Figure 3(a) shows an end view, figure 3(b) a cross section of said cell, along a transverse axis T4 of said superstructure beam.
  • Figure 4 shows a schematic perspective view, analogous to figure 1 , showing said electrolytic cell in a second position of its mounting process.
  • Figure 5 shows a detail of figure 4, illustrating in particular floating parts of intermediate legs being distant from fixed rest means, with a first gap.
  • Figure 6 is a detail view analogous to figure 5, showing said electrolytic cell in a third position of its mounting process, said figure 6 illustrating in particular floating parts of intermediate legs being distant from fixed rest means, with a second gap inferior to said first gap.
  • Figure 7 is a detail view analogous to figure 5, showing a variant of floating parts and rest means of intermediate legs.
  • Figures 8 and 9 are schematic end views, showing two alternative embodiments of intermediate support members being part of the cell according to the invention.
  • Hall-Heroult process as such, the way to operate the latter, as well as the general structure of a Hall-Heroult electrolysis pot are known to a person skilled in the art and will not be described here in more detail. It is sufficient to explain that the current is fed into the anode beams fixed to the superstructure, and then flows to the plurality of anodes in contact with the liquid electrolyte where the electrolytic reaction takes place. Then the current crosses the liquid metal pad resulting from the process and eventually will be collected at the cathode block.
  • the terms“upper” and“lower” refer to mechanical elements in use, with respect to a horizontal ground surface.
  • conductive means “electrically conductive”.
  • Figure 1 describes a typical arrangement of a Hall-Heroult electrolysis cell, which comprises amongst others a superstructure referenced 1 as a whole, holding a plurality of anodes, as well as a potshell referenced 10 as a whole.
  • Said superstructure mainly comprises a fixed frame 2 essentially formed by an elongated beam 4, the main longitudinal axis thereof is noted L4 and the main transversal axis thereof is noted T4.
  • Said beam 4 rests on several support members, which will be detailed hereafter.
  • the superstructure beam according to the invention can be manufactured by welding from plates, profiles and other shapes. It can comprise one or more beams that extend over the whole length, but this is not a preferred embodiment. Even though it comprises several beams, it is referred to one single“beam”.
  • Said superstructure beam can comprise all the features and functionalities of prior art superstructures, some of which are shown on figure 1 , such as the anode frame, alumina supply flanges, aluminium fluoride supply flanges, cover plates, passageways for crust brakers, exhaust air ducts (not shown on figure 1 ).
  • superstructure 1 is intended to hold classic anode assemblies, which are schematically represented only on figure 4. Let us note that they are not illustrated on figure 1 , since the latter relates to a first stage of the mounting process, wherein said anode assemblies are not attached to said beam 4.
  • Said potshell which rests on a not shown concrete support, which is known as such, comprises a bottom wall 11 , from which peripheral walls extends upwards.
  • Said peripheral walls comprise two parallel side walls 12 and 13, as well as two parallel end walls 14 and 15.
  • Said potshell is equipped with a set of parallel, vertical stiffeners or cradles, referenced as 16.
  • Said stiffeners are shown on figures 2 and 3a, but not on figure 1. They are depicted only in a schematic manner as vertical lines, as their structure is not significant for the present invention.
  • the above walls 11 to 15 define an inner volume V10 of the potshell, which is opened upwards and ensure the reception of further elements of the cell, shown on figure 2.
  • the top of said walls 11 to 15 is provided with an upper peripheral rim, in a way known as such.
  • This rim comprises two facing side parts, or side rims 17, as well as two facing end parts, or end rims 18.
  • the side wall of one potshell of a given cell is separated from facing potshell of an adjacent cell, by a so called intercalary space.
  • the present invention is more particularly directed to the means for supporting the main beam 4.
  • Said beam rests first on classic end support means, provided at both longitudinal ends of said beam.
  • end support means each comprise two legs 6 and 6’, as well as 8 and 8’, their structure is known as such. Preferably, these legs rest on the ground, as can be seen on figure 2.
  • the superstructure is also provided with intermediate support members, which form on the contrary part of the invention.
  • said intermediate support members comprise one single gantry 20, which extends along axis T4 viewed from top.
  • Said gantry is provided at a midpoint of beam 4, preferably symmetrical with respect to the long and short axis of the potshell.
  • X4 the length of beam 4, i.e. its dimension along axis L4.
  • Intermediate support members, such as gantry 20, are advantageously located at a longitudinal position or length X20, which is about 50% of whole length X4, i.e. about ( X4)/2.
  • Said gantry 20 is essentially formed by a central body 30 and two lateral legs 40 and 50.
  • Body 30 comprises a substantially horizontal core 32, as well as two arms 34 and 36 each extending slightly downwards from said core 32.
  • the core of said body 30 is permanently attached to said beam 4 by way of classic means, in particular by welding.
  • Each leg 40 or 50 is essentially formed by two separate parts, i.e a lower part 41 or 51 , as well as an upper part 45 or 55.
  • Lower part 41 or 51 is called fixed part, or fixed leg, or mast, i.e. it cannot move in operation with respect to said ground. Said lower part may be attached directly to the ground, by any appropriate means.
  • lower free end 42 or 52 of each lower part is fixed on a respective side rim 17 of potshell by any appropriate means, in particular by welding.
  • each pole 45 or 55 is integral with a respective arm 34 or 36.
  • one pole may be attached to a respective arm by way of fixing means, such as welding.
  • Each mast and each pole are elongated, with any appropriate transverse shape, in particular circular or rectangular. Facing free ends of said masts and said poles are adapted for mutual abutment. In other words, lower free end 46 or 56 of said pole 45 or 55 may rest on upper free end 43 or 53 of said mast 41 or 51.
  • Figures 4 and 5 illustrate the second mounting position of the cell, which corresponds to the so-called“start-up” thereof.
  • All anode assemblies have been attached in place on the superstructure, provided a classic routine.
  • Said anode assemblies, which are arranged in two rows, comprise classic anodes and anode rods, which allow the attachment of said anodes to said superstructure.
  • the vertical gaps between facing free ends 43 and 46, as well as 53 and 56, are noted x on figure 5.
  • these gaps x are not “normal” functional gaps of said superstructure. In other words, even though they may arise in some cases, in particular due to stresses under varying conditions of load or temperature, these gaps normally do not exist.
  • the superstructure beam should be designed such that the deflection in this case does not exceed x mm per meter of length, x being defined as above. In an advantageous embodiment, for a 24 m long superstructure beam the upward deflection does not exceed 20 mm. in operation, said gap x is advantageously filled with not shown shims or wedges. It should be noted that this definition of x also defines X 2 and X 3 .
  • Figure 6 illustrates the third mounting position of the cell, which corresponds to normal operation of the cell, at a temperature that is smaller than the start-up temperature.
  • This causes the downwards displacement of poles 45, 55 with respect to mast 41 , 51 , which is shown by arrows f45 on figure 6.
  • the magnitude of this downwards displacement f45 is lower than that of above described upwards displacement F45. Therefore, as shown on said figure 6, lower free end 46 or 56 of said pole 45 or 55 may still be remote from upper free end 43 or 53 of said mast 41 or 51.
  • the lower free ends 46, 47 rest on upper free ends 43, 53 but the superstructure beam 4 experiences reduced stress with respect to the situation in which there are no intermediate support members 20.
  • the superstructure has a concave downward deflection of designed or acceptable level for normal operation at the stage depicted on figure 6.
  • the intermediate support members are free floating.
  • the superstructure beam 4 still rests entirely on its end support members 6, 6’, 8 and 8’.
  • x’ the vertical gap between facing free ends 43 and 46, as well as 53 and 56, on figure 6.
  • Gap x’ of figure 6 is inferior to gap x of figure 5.
  • this gap x’ is about x/2, x being the gap of figure 5.
  • the free floating legs of the central support members are not in contact with the surface on which they rest in first stage of figure 1.
  • shims or wedges should be used to fill the gap x’, the same way as in the stage of figure 5.
  • these gaps x’ are not“normal” functional gaps of said superstructure.
  • poles 45, 55 may slide with respect to mast 41 , 51 , along a substantially horizontal direction. This sliding may in particular be due to thermal expansion of the cell in horizontal plane. According to the invention, provisions should advantageously be taken for allowing such sliding, in order to avoid the built-up of unnecessary mechanical stresses.
  • the amplitude of such sliding movement is typically of the order of a few millimeters and will depend on the construction of the superstructure.
  • facing free ends of said masts and said poles are provided with means for means for facilitating mutual sliding of said facing free ends.
  • This means may be of any appropriate type.
  • lower end 46 of pole 45 is provided with a first sliding plate 45’, cooperating with a facing sliding plate 41’ provided at the upper end 43 of mast 41.
  • the surface of said plates 41’ and 45’ is larger than that of pole and mast, in view of a better sliding.
  • a bronze alloy plate (not shown on the figures) can be inserted between sliding plates 41’ and 45’; said bronze alloy plate can be secured to one of the sliding plates 41’, 45’.
  • Figure 8 illustrates a further alternative of the superstructure according to the invention.
  • mechanical elements analogous to that of figures 1 to 6 are given the same reference numbers, added by 100.
  • Superstructure 101 of figure 8 differs from that of figures 1 to 6, in particular in that floating parts are formed by the two lateral legs 140, 150 of said gantry 120.
  • rest means are formed by the ground itself, or by the rim 117 of the potshell.
  • Figure 8 depicts gap x, which is formed between lower end 140’, 150’ of legs 140, 150 and said rest means.
  • FIG. 9 illustrates still a further alternative of the superstructure according to the invention.
  • Superstructure 201 of figure 9 differs from that of figures 1 to 6, in particular in that the whole gantry 220 is attached to the ground and said beam 204 is mobile with respect to this whole gantry.
  • said rest means are formed by upper part 230’ of main body 230 of said gantry 220, whereas facing face of said elongated beam 204, i.e. lower part 204’ thereof, forms abutment means adapted to cooperate with said rest means.
  • Figure 9 depicts gap x, which is formed between lower end 140’, 150’ of legs 140, 150 and said rest means.

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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)

Abstract

L'invention concerne une superstructure (1 ; 101 ; 201) pour une cellule électrolytique, appropriée pour le procédé d'électrolyse Hall-Héroult, ladite superstructure comprenant un châssis de forme pratiquement rectangulaire, ledit châssis comprenant au moins une poutre dite longitudinale (4 ; 104 ; 204), des premiers éléments de support (6, 6', 8, 8') ou éléments de support terminaux, disposés aux extrémités longitudinales opposées de ladite poutre, et des seconds éléments de support (20 ; 120 ; 220) ou éléments de support intermédiaires, disposés en un endroit longitudinal intermédiaire entre lesdites extrémités de ladite poutre, ladite superstructure étant caractérisée en ce qu'elle comprend une partie dite flottante (45 ; 120 ; 204), qui est immobile par rapport à ladite poutre au moins le long d'une direction choisie entre la direction verticale et la direction horizontale mais qui est mobile lors du fonctionnement par rapport au sol le long d'au moins une direction choisie entre la direction verticale et la direction horizontale, ladite partie flottante comprenant des moyens de butée (46 ; 140' ; 204'), lesdits moyens de butée pouvant coopérer avec des moyens de repos (43 ; 117 ; 230') fixes par rapport au sol.
PCT/IB2019/051308 2018-02-21 2019-02-19 Cellule électrolytique dotée d'une superstructure ayant des pattes intermédiaires, appropriée pour le procédé hall-héroult WO2019162817A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1802791.2A GB2571274A (en) 2018-02-21 2018-02-21 Electrolytic cell with a superstructure having intermediate legs, suitable for the Hall-Heroult process
GB1802791.2 2018-02-21

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WO2019162817A1 true WO2019162817A1 (fr) 2019-08-29

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4436607A (en) * 1981-07-14 1984-03-13 Swiss Aluminium Ltd. Anode superstructure of a fused salt electrolytic cell and pot room fitted out with same
US4720333A (en) * 1985-05-30 1988-01-19 Aluminium Pechiney Electrolysis tank superstructure with intermediate gantry, for the production of aluminium
US5378338A (en) * 1992-08-20 1995-01-03 Aluminium Pechiney Superstructure for a very high power electrolysis cell for the production of aluminum
WO2012037611A1 (fr) * 2010-09-23 2012-03-29 Aluminium Smelter Developments Pty Ltd Système de levage d'anodes
WO2016174313A1 (fr) * 2015-04-27 2016-11-03 Fives Ecl. Dispositif de manutention d'un équipement d'une cellule d'électrolyse
WO2017072618A1 (fr) * 2015-10-28 2017-05-04 Dubai Aluminium Pjsc Superstructure pour cellule électrolytique, comportant des moyens de déplacement d'un montant d'anodes par rapport au bâti de cette superstructure

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1533456B1 (de) * 1965-04-09 1969-10-23 Pechiney Prod Chimiques Sa Anodentraggeruest fuer eine Schmelzflusselektrolysezelle
CN102465315B (zh) * 2010-11-05 2014-09-17 贵阳铝镁设计研究院有限公司 制止电解槽启动期间槽壳上拱的电解槽结构

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4436607A (en) * 1981-07-14 1984-03-13 Swiss Aluminium Ltd. Anode superstructure of a fused salt electrolytic cell and pot room fitted out with same
US4720333A (en) * 1985-05-30 1988-01-19 Aluminium Pechiney Electrolysis tank superstructure with intermediate gantry, for the production of aluminium
US5378338A (en) * 1992-08-20 1995-01-03 Aluminium Pechiney Superstructure for a very high power electrolysis cell for the production of aluminum
WO2012037611A1 (fr) * 2010-09-23 2012-03-29 Aluminium Smelter Developments Pty Ltd Système de levage d'anodes
WO2016174313A1 (fr) * 2015-04-27 2016-11-03 Fives Ecl. Dispositif de manutention d'un équipement d'une cellule d'électrolyse
WO2017072618A1 (fr) * 2015-10-28 2017-05-04 Dubai Aluminium Pjsc Superstructure pour cellule électrolytique, comportant des moyens de déplacement d'un montant d'anodes par rapport au bâti de cette superstructure

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GB2571274A (en) 2019-08-28

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