Apparatus for anodic preparation for an aluminum electrolysis plant and method of operating the same, aluminum electrolysis plant and method of operating the same, and method for producing aluminum

Abstract

The present invention is an apparatus (30, 35) for anodic preparation in an aluminum electrolysis plant. The anodic preparation apparatus includes an elongated body (31) as a beam, traveling means configured to enable the movement of the elongated body, and an anodic preparation machine (32) attached to the elongated body. The anodic preparation machine includes at least two operating devices (45, 55, 65, 75, 85, 95), and the anodic preparation function, unlike the lifting of the cell and the raising of the anodic beam, includes at least two support assemblies (40, 50, 60, 62, 70, 72, 80, 81, 82, 83, 90, 91, 92, 93), each of which is configured to support the respective operating device with respect to the elongated body. The operating devices (45, 55, 65, 75, 85, 95) are movable independently of each other along at least one of the longitudinal axis (L31) and the vertical axis (ZZ) of the elongated body (31).

Description

Technical Field

[0001] The present invention relates to the field of molten salt electrolysis, and more precisely, to a method for replacing an anode and an anode assembly for use in the Hall-Héroult process for producing aluminum by molten salt electrolysis.

[0002] Since carbon anodes are consumed during the electrolysis process, they need to be replaced regularly. The present invention relates to an apparatus for replacing an anode assembly in an electrolytic cell by being used together with a dedicated overhead crane, forming a system for replacing the anode assembly by the overhead crane, and relates to an apparatus capable of performing specific maintenance operations related to the replacement of the anode assembly.

Background Art

[0003] The Hall-Héroult process is the only continuous industrial process for producing metallic aluminum from aluminum oxide. Aluminum oxide (Al2O3) is dissolved in a molten cryolite (Na3AlF6)-based electrolyte. The dissolved alumina is electrochemically decomposed in an electrolytic cell, typically at a temperature of 950 °C to 970 °C, with the aid of a consumable anode. A typical rectangular electrolytic cell (also called a "pot") used in modern Hall-Héroult cells usually consists of a steel shell (the so-called pot shell) with a heat-insulating lining containing refractory bricks, providing heat resistance, and an array of laterally arranged cathode blocks, usually made of graphite, anthracite, or a mixture of both. These blocks are joined together, and each block has one or more metal bars embedded in it for connection to the negative side of a DC power supply. Its sidewalls are also sealed with a carbonaceous lining based on a carbonaceous material, forming a leak-proof container for the low-density electrolyte containing the produced liquid aluminum and dissolved alumina. An electrically insulated superstructure is fixed to the top of the steel pot shell and is designed to house hoppers, breakers, and feeders for the consumable materials (aluminum oxide and aluminum fluoride). The superstructure supports an aluminum busbar (also called an "anode beam") of adjustable height to which the anodes are fixed and allows the atmosphere to surround it so that emissions can be collected and properly treated.

[0004] In the Hall-Héroult process, the anodes are usually pre-fired rectangular parallelepipeds made of carbonaceous materials. The anodes are fixedly connected to so-called anode hangers. The latter serve two different purposes: keeping the carbon anodes at a predetermined distance from the cathode and conducting current from the anode beam to the carbon anodes. The anode hangers are removably fixed to the protruding anode beam using hooks and clamps. The anode hanger includes an upper part called the "anode rod" connected to the anode beam and a lower part called the "anode yoke". The anode yoke has a plurality of legs, each of which terminates in a cylindrical stub that is embedded in a pre-formed stub hole in the carbon anode and fixed with cast iron that functions as a heat-resistant and conductive contact element. This process is called "lodging". The assembly formed by fixing the carbon anode to the anode hanger is called the "anode assembly".

[0005] A plurality of anodes, supported by adjustable anode beams and usually arranged in two rows, are immersed in the molten salt electrolyte up to the required height on the liquid aluminum cathode. The anodes and cathodes are connected to an external busbar circuit and can pass current through the cell at a voltage determined by the controller, which is always between 3.8V and 5V. This arrangement, combined with the supplied electrical energy, enables the electrochemical decomposition of ionic species resulting from dissolving aluminum oxide in a molten fluoride-based solvent. The aluminum-containing cationic species formed by the dissolution of alumina are electrochemically reduced on the surface of the metal pad to become liquid aluminum. At the same time, the oxyanions formed from alumina are reactively oxidized to carbon monoxide at the carbon-anode interface and further oxidized mainly to carbon dioxide. The resulting metallic aluminum does not mix with the liquid electrolyte and has a higher density than the liquid electrolyte, so it accumulates as a liquid metal pad on the cathode surface and needs to be removed from time to time, usually by sucking it into the crucible (the so-called "tapping" method), and the crucible is usually transported by a vehicle moving on the ground floor or a ceiling crane.

[0006] Due to the electrochemical consumption of carbon, the life of each anode assembly is limited. Furthermore, to maintain the quality of the metal and to prevent the metal part of the anode assembly from contacting the electrolyte, only about 80% of each anode is electrochemically and chemically consumed. Beyond this, it is regarded as a "used anode assembly" and needs to be replaced. Depending on the design and dimensions of the carbon block, the anode assembly usually has an operating life of 18 to 30 days. Since modern electrolytic cells are usually composed of 16 to 40 anodes, the replacement of one or a set of anodes per pot is carried out every 24 to 48 hours, usually every 32 hours. To minimize the impact on the state of the operating cell, all used anode assemblies are scheduled to be replaced regularly so that each is replaced once during the operating life cycle. Therefore, depending on the number and size of the anodes, the replacement of anodes or anode pairs is usually carried out at intervals of about once every 24 to 48 hours per cell.

[0007] Since the Hall-Héroult process is a continuous process, along with the removal of liquid metal, the replacement of anodes is the most frequently performed regular maintenance operation. The replacement of anodes is carried out by replacing the used anode assembly with a new one. The used anode assembly is transported to a dedicated workplace in the plant, where the remains of the used carbon anode are removed from the anode yoke, and the anode hanger of the used anode assembly is cleaned and reused for the new anode assembly.

[0008] The current technologies and working methods for removing used anode assemblies and replacing them with new ones include a number of labor-intensive procedures that not only lead to excessive emissions of harmful substances, waste the accumulated energy, cause obstacles to performance degradation, but also pose health hazards to workers.

[0009] The above-mentioned cathode block forming the bottom of the electrolytic cell goes through a series of very slow deterioration stages, and its lifespan is usually limited to 5 to 8 years. In case of failure, the superstructure is removed, the used pot shell is lifted by a large overhead crane (so-called "Cathode Transport Crane", abbreviated as CTC), and a lined pot shell for replacement is placed to prepare for the trial operation. The cathode transport crane usually requires a very high lifting force exceeding 200 tons.

[0010] Electrical energy is the main operating cost in the Hall-Héroult process. The two factors of energy waste, namely the heat loss of the cell and the decrease in current efficiency, are expanding due to the current procedures and the devices enabling anode replacement. Unnecessary heat loss occurs due to the waste of the energy content of the anode cover material used for the spent anode. Also, high radiant heat loss occurs during the extended time of cavity cleaning required due to the secondary effects of the jackhammer operation (crushing operation) of the sealing crust of the anode cover. There is an inevitable spillage of lumps of anode cover material into the electrolyte caused by the jackhammer operation, which causes turbulence in the metal pad and reduces the current efficiency.

[0011] In addition to carbon dioxide, the gaseous emissions in the Hall-Héroult electrolysis process also include particulate condensed fluorides generated from the electrolyte, hydrogen fluoride generated from the impurities of refinery-grade alumina dissolved in the electrolytic bath, and trace amounts of SO2 generated from the impurities of the anode carbon. These are harmful to workers and the environment. Therefore, since the 1970s, the gas emissions from the cells in the Hall-Héroult process have not been released into the environment and have been purified. More precisely, the gaseous emissions from the electrolytic pot are collected using protective devices such as a hood system, and are processed at a gas treatment station to remove fluorine compounds and other harmful compounds before the collected air is released into the environment. The conventional working method of replacing the spent anode leaks some of these harmful chemicals into the working environment.

[0012] In practice, the hood system at the electrolytic cell level includes an array of movable hood panels, which are typically arranged on an elongated frame that extends substantially parallel to each of two parallel anode lines. This frame supports two fixed end walls located at opposite ends of the anode line, and several panels (so-called "hood panels") are provided between these end walls facing the front of the anode. These hood panels are typically shaped to ensure optimal protection and sealing. They also function as thermal shields, limiting the heat loss of the electrolytic cell and protecting the operator. During maintenance, the hood panels can be removed as needed to access the anode hangers.

[0013] Currently, the replacement of the anode assembly (this operation is more conventionally referred to as "anode replacement" and this expression will be used hereinafter) is generally carried out using a so-called pot-tending machine and a floor operator. During anode replacement, several individual operations need to be performed, starting with removing at least one (more frequently, two adjacent) pot hood panels to access the anode assembly to be removed. The removal of the anode assembly is also carried out by the pot-tending machine controlled by the operator. The preparatory work before this is to break the solidified electrolyte / vapor / alumina coating used to save heat and prevent air from entering the anode carbon surface not immersed in the electrolyte. The actual removal work of the used anode assembly includes loosening the clamp that fixes the anode rod to the height-adjustable anode beam, vertically lifting the used anode assembly, and placing the removed anode assembly on the floor (usually inside a pallet). In an appropriate working procedure, it is usually necessary to clean the cavity of the solidified electrolyte film that has entered the electrolyte using a cavity scoop. Next, a new anode assembly is inserted into the cavity, fixed to the anode beam, and accurately positioned. In particular, the bottom of the anode needs to be placed at a predetermined height to accurately control the distance between the anode and the cathode. Next, the hood panel is attached to a predetermined position (in some cases, another inspected or in good condition hood panel may be used).

[0014] This procedure always takes 10 to 20 minutes. Since toxic gas may leak from the pot when the hood is open, it is desirable to minimize the time the hood is open and the time the floor operator is present.

[0015] The pot tending machine (PTM) is manufactured by ECL (five groups) or Noell-NKM (reel group) and has been used for many years. Its basic function is to carry the anode assembly during an operation known as anode beam raising. Since the carbon anode is gradually consumed during the electrolysis process, in order to keep the distance between the anode and the cathode constant, it is necessary to gradually lower the anode beam that holds all the anodes in place. Eventually, the position of the anode beam reaches the physical lower limit. At this point, it is necessary to raise the anode beam using a special anode beam raising device (ABRE) installed on the pot tending machine. During this process, while the anode beam slides relative to the anode rod to maintain electrical contact during raising, the anode rod is mechanically disconnected from the anode beam (the anode connector loosens), but the anode rod remains in electrical contact with the anode beam. The anode is held in place by the ABRE, which maintains electrical contact by pressing the anode rod against the anode beam.

[0016] Modern pot tending machines have several additional features. These can be combined with an overhead traveling crane (also called a bridge crane) and a cabin for the PTM operator. These can also be used to carry the pot during the tapping process. The lifting capacity of modern pot tending machines usually exceeds 25 tons, and often exceeds 35 metric tons or 40 metric tons, especially when designed for tapping.

[0017] There are also anode exchange devices mounted on dedicated ground vehicles. These are usually specially designed trucks. Such anode exchange vehicles are sold by companies such as HENCON and TECHMO in addition to GLAMA. They may be too large to be used in potlines where the distance between two adjacent electrolytic cells is very narrow. Furthermore, more generally, it may not be desirable to use vehicles at the floor level between electrolytic cells, and as a policy, it may be considered even less desirable to use long metal tools that extend horizontally at the floor level between the electrolytic cell and the potroom building, as this represents an electrical hazard.

[0018] The pot tending machine integrated with the overhead crane is designed to avoid such electrical hazards. Pot tending machines that perform specific tasks in the anode assembly replacement process of the Hall-Héroult cell are described in a number of patent publications. These machines can have varying degrees of automation. WO 2004 / 079046 and US Patent No. 8,888,156 describe handling grippers for grasping the anode rod before transporting it with the crane. WO 2004 / 101853 describes a tool for unlocking and locking a clamp that secures the anode rod to the anode beam. US Patent No. 8,066,856 describes a pneumatic impact generator that can improve the electrical contact between the anode rod and the anode beam when installing a new anode assembly. WO 2005 / 095676 describes maintenance equipment for anode replacement with various tools attachable to the overhead crane, and this mobile maintenance equipment includes a cabin for the operator. WO 2006 / 010816 and US Publication No. 2007 / 0205104 describe further tools for such maintenance equipment. US Patent No. 8,273,223 describes a tool for handling the hood panel. WO 2010 / 079266 describes maintenance equipment with a crust shovel for cleaning the cavity during anode replacement. WO 2011 / 130892 and US Patent 2012 / 0234690 disclose other designs of the crust shovel. US Publication 2008 / 0251392 describes a method of replacing an anode that includes automatically positioning an anode assembly in place of a used anode assembly. WO 2006 / 030092 describes another method that includes a device for measuring the vertical distance traveled by a tool using electromagnetic or sound waves. WO 2016 / 128631 and French Patent 3 032 457 disclose a pot tending machine with two independent maintenance facilities that can perform different functions in parallel, thereby speeding up the anode replacement process.All patents described in this paragraph are assigned to E.C.L.

[0019] These prior art pot tending machines are aimed at simplifying the work of floor operators by reducing the number of individual tasks that the floor operator has to perform, such as handling the hood panel, assisting in the accurate positioning of the anode, cleaning the cavity, etc. Some of these machines can replace the floor operator and can be controlled only by the PTM operator from the cabin. Such machines are described, for example, in the publication "Automation of anode change in electrolysis pots: impact on process and safety performance" by N. Dupas, Light Metals 2009 (TMS), p. 515 - 518, and in International Publication No. WO 2015 / 132479 (E.C.L.) which describes an automatic pot tending machine for anode change including a plurality of tools and storage elements for the hood panel. The paper "New ECL integrated service robot: towards an automated, efficient and environmentally friendly smelter" by J. Guerin and A.G. Hequet, published on pages 695 - 697 of Light Metals (TMS) in 2015, also presents a fully automatic anode change robot that does not require a crane operator. This new robot is equipped with a telescopic mast fixed to an overhead crane, and the mast is equipped with a plurality of individual tools each dedicated to an individual task.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0020] This system has several drawbacks. First, in order to minimize the release of harmful gases sucked into the exhaust gas purification system into the atmosphere regardless of the presence or absence of a floor operator, it is desirable to shorten the time the hood is open. Second, existing automatic or semi-automatic anode changers do simplify the operator's work, but they take more time to change an anode than conventional methods. And third, all existing automatic or semi-automatic anode changers rely on the availability of an overhead crane. Considering that these cranes may be needed to perform other tasks unrelated to anode changing, even if the floor operator becomes unnecessary, it is not particularly desirable to increase the total time required for anode changing, and the crane time available for anode changing can be a limiting factor when the crane is needed elsewhere on the potline. The inventors recognized the desirability of moving to a fully automated anode changing process while attempting to overcome these drawbacks in conventional anode changing robots.

Means for Solving the Problems

[0021] The present invention provides a new device for anode maintenance for an aluminum electrolysis plant capable of replacing an anode. Replacing an anode is a rather complex procedure involving a certain number of individual operations, such as removal (and replacement) of the hood panel, unlocking (and locking) of the anode hook, removal (and replacement) of the anode assembly, cleaning by suction, etc. The term "maintenance" used herein refers to general maintenance work, and according to the present invention, the device for anode maintenance can perform one or more tasks related to anode replacement and, in some cases, additional tasks not related to anode replacement. The device for anode maintenance includes a crane beam and a specific maintenance machine, and the maintenance machine includes a movable operating device. The latter can perform one or more individual operations performed on an individual anode assembly (locking and unlocking of the anode lock, lifting of the used anode assembly, etc.) and / or one or more individual operations performed in relation to the replacement of an individual anode assembly (opening and closing of the anode hood, cleaning by suction near the anode in the pot, etc.).

[0022] According to the present invention, the problem is solved by two independent means that can be combined.

Effect of the Invention

[0023] According to the first aspect of the present invention, the apparatus for anodic dressing is an additional and independent crane beam configured to move on the rails of an existing overhead crane and / or on the rails of an existing pot tending machine (which may all be the same rails). However, since this uses a dedicated independent tool instead of a complex multi-functional dressing facility, it is much lighter than a conventional pot tending machine. As a result, for the apparatus for anodic dressing according to the present invention, a lifting force of less than about 20 tons, preferably less than about 10 tons, is sufficient.

[0024] Furthermore, the inventors recognized that conventional anode exchange robots tend to operate quite slowly because all of their tools are mounted on one or two dressing facilities, and each dressing facility can perform only one function at a time. As a result, these individual tools cannot operate completely independently of each other.

[0025] According to the second aspect of the present invention, the apparatus for anodic dressing according to the present invention includes a plurality of independent tools each attached to a separate dressing facility. This enables each tool, which is specialized for a specific function, to operate completely independently. This complete independence allows, in some cases, two or more tools to perform operations simultaneously, and in some cases, two or more tools to perform different functions simultaneously.

[0026] A first object of the present invention is an apparatus for anodic maintenance in an aluminum electrolysis plant, wherein the aluminum electrolysis plant comprises electrolytic cells (C1-Cn, C’1-C’n) of at least one line (L1, L2) connected in series, each cell being connected to a cathode busbar and each cell having a plurality of anode assemblies connected to an anode beam. The apparatus for anodic maintenance is intended to be provided on at least one line of the plant. The apparatus for anodic maintenance includes an elongate body as a beam, traveling means configured to move the elongate body along a traveling direction substantially parallel to the main axis of the line (L1, L2), and an anodic maintenance machine attached to the elongate body. The anodic maintenance machine includes at least two operating devices, each configured to perform at least one specific anodic maintenance function, the anodic maintenance function being different from lifting of the cell and lifting of the anode beam, and at least two support assemblies, each support assembly being configured to support each of the operating devices with respect to the elongate body. The two operating devices are movable independently of each other along at least one of the longitudinal axis and the vertical axis of the elongate body.

[0027] According to another aspect of the present invention, at least one support assembly includes at least one carrier movable with respect to the elongate body along the longitudinal axis (L31) of the elongate body, and each of the operating devices is fixed with respect to the carrier at least with respect to being parallel.

[0028] According to another aspect, at least one support assembly includes at least one carrier movable with respect to the elongate body along the longitudinal axis of the elongate body and at least one drive member including drive means configured to move the operating device with respect to the carrier along the vertical axis (ZZ).

[0029] Furthermore, at least one of the support assemblies includes the two carriers and the two drive members, and the drive means is configured to move one operating device along a vertical axis relative to the carrier.

[0030] The elongate body includes at least one, particularly at least two, parallel rails, and at least one of the rails is provided with at least one track for the movement of at least one of the carriers.

[0031] The specific anode servicing function is advantageously selected from lifting a new anode, suction cleaning of the anode covering material surrounding and / or covering the anode, cutting the hard coating material surrounding the anode, lifting a used anode, placing a new anode at a specific height, adding anode covering material on and around the anode, recording an image representing the position and shape of the anode, moving a hood panel to provide access to the anode, and returning the hood panel after completion of the anode exchange.

[0032] It is possible and advantageous to design the device such that the lifting force of each operating device is less than 20 metric tons, preferably less than 15 metric tons, and more preferably less than 10 metric tons.

[0033] In one embodiment, the anode servicing device according to the invention includes at least two so-called lifting operating devices, each lifting operating device being adapted to lift a respective anode assembly.

[0034] According to another embodiment, it further includes a so-called multi-purpose operating device provided with a head, the head being configured to cooperate with tools removably fixed to a separate operating device and / or tools removably fixed to the multi-purpose operating device.

[0035] A second object of the present invention is an aluminum electrolysis plant including at least one line of substantially rectangular electrolytic cells, the plant further comprising means for electrically connecting the cells in series and means for connecting the cathode busbar of a cell to the anode beam of a downstream cell, the plant comprising at least one weight lifting device and / or at least one pot tending assembly (25), the weight lifting device, if present, comprising an elongate body as a beam, traveling means configured to move the elongate body along a traveling direction substantially parallel to the main axis of the line, and a weight lifting machine attached to the elongate body and configured to perform at least one function of the so-called weight lifting type including lifting of the superstructure and a pot shell having a damaged or new lining, the pot tending assembly, if present, comprising an elongate body as a beam, traveling means configured to move the elongate body along a traveling direction substantially parallel to the main axis of the line, and a pot tending machine attached to the elongate body and configured to perform at least one function of the so-called main type including raising and tapping of the anode beam, the line of the plant further comprising at least one anode preparation device according to any of the embodiments and variations of the present invention, the anode preparation device comprising a body, traveling means configured to move the body along the traveling direction, and an anode preparation machine attached to the body and configured to perform at least one specific anode preparation function, further, at least one of the functions of the weight lifting type and / or at least one of the functions of the main type is separate from the anode preparation function, while at least one of the specific anode preparation functions is separate from the functions of the weight lifting type and the main type, in particular separate from the lifting of the cell, the raising and tapping of the anode beam.

[0036] This plant further includes at least one common travel path that can be used by the travel means of the anode maintenance device, and is configured to cooperate with the travel means of the heavy object lifting device and / or the travel means of the pot tending assembly. In particular, it includes two common travel paths provided on both sides of the cell with reference to the horizontal axis of the line.

[0037] A third object of the present invention is a method of operating an anode maintenance device according to the present invention. The anode maintenance device is particularly a part of an aluminum electrolysis plant according to the present invention. The operation method includes lifting a so-called replacement anode assembly, which is intended to replace a so-called used anode assembly, with a first lifting operation device of the anode maintenance device; moving the anode maintenance device carrying the replacement anode assembly to a position near the used anode assembly; lifting the used anode assembly with a second lifting operation device of the anode maintenance device; and placing the replacement anode assembly at the original position of the used anode assembly. More preferably, the operation method further includes analyzing the shape of the used anode to determine the height position of the replacement anode, and / or cleaning the material around the used anode assembly by suction, storing at least a part of the material, and pouring at least a part of the stored material around the replacement anode assembly.

[0038] The operation method can further include arranging the heavy object lifting device or the pot tending assembly above one predetermined cell of the plant or between two adjacent cells; arranging a first anode maintenance device on top of a first cell located on a first side of the predetermined cell or the two adjacent cells with respect to the main shaft; and / or arranging a second anode assembly on top of a second cell located on a second side of the predetermined cell or the adjacent cells with respect to the main shaft.

[0039] More preferably, the operation method further includes performing at least one specific anode maintenance function on the first cell and / or performing at least one specific anode maintenance on the second cell.

[0040] Yet another object of the present invention is a method for producing aluminum by the Hall-Héroult electrolysis process, characterized in that the method is carried out in an aluminum electrolysis plant according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figs. 1 to 18 illustrate embodiments of the present invention and do not limit the scope of the present invention.

Figure 1

Figure 2

Figure 3

Figure 4

Figures 5-6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Description of Reference Numerals

[0042] In the figures, the following reference numerals are used. 1: Electrolytic cell (prior art) 2: Side wall of pot shell 4: Bottom of pot shell 3: Lining 5: Anode assembly 6: Anode rod of 5 7: Anode of 5 5U: Used anode assembly 6U: Anode rod of 5U 7U: Anode of 5U, 8: Cathode block, 9: Cathode collector bar 10: Anode frame, 11: Electric field cell, 12: Liquid aluminum pad 13: Hood panel, 14: Clamp, 15: Anode assembly 16, 16’: Hut (building), 17, 18: Side walls of the hut, 19: Upper wall of the hut 20, 21: Travel path, 25: Pot tending machine (PTM) 26: Body of 25, 27: Hoisting machine of PTM, L31: Main shaft of body 31 30: Device for primary anode maintenance, 31: Body of 30 32: Machine for anode maintenance, 33, 33’: Rails of 32 34, 34’: Tracks of the rails, 35: Device for secondary anode maintenance 40: Carrier of 45, 41, 42: Side walls of the pot shell 45: Hopper, 50: Carrier of 55, 55: Crust breaker, 60: Carrier of 65 62: Platform of 65, 65: Bucket shovel 70: Carrier of 75, 72: Platform of 75, 75: Multi-tool robot 750: Deck of 75, 752: Proximal arm of 75, 753: Intermediate arm of 75 754: Distal arm of 75, 756: Rotating part of 75, 758: Head of 75 76: Camera of 75, 77 - 79: Tools of 75, 80, 81: Carriers of 85 82, 83: Platforms of 85, 85: Lifting robot 90, 91: Carriers of 95, 92, 93: Platforms of 95 95: Lifting and hoisting robot C1 - Cn, C’1 - C’n, Ci, C’i, Cj, C’j: Electrolytic cells L1, L2: Rows of electrolytic cells, ZZ: Vertical axis, XX: Main axis of the cell row, YY: Transverse axis of the cell row

Mode for Carrying Out the Invention

[0043] The present invention relates to the layout of a plant, also called an aluminum smelting plant or aluminum smelter, which uses the Hall-Héroult process. This plant includes a plurality of electrolytic cells (potlines) connected in series. Since the Hall-Héroult process itself, its operating method, and the general structure of the above-mentioned electrolytic cells are known to those skilled in the art, they will not be described here. In this specification, the terms "upper" and "lower" refer to mechanical elements in use with respect to a horizontal working surface. Further, unless otherwise specified, "conductive" means "electrically conductive".

[0044] As schematically shown in FIG. 1, the aluminum smelter of the present invention typically comprises a plurality of electrolytic cells arranged along two parallel lines L1 and L2, each electrolytic cell including n cells, namely C1 to Cn and C'1 to C'n. Thus, the electrolysis current flows step by step from one cell to the next along the arrow DC. The number of cells in series is usually from 50 to over 250, and in the latest smelters it may exceed 400, but this number is not important for the present invention.

[0045] The electrolytic cells are rectangular and are arranged horizontally (side by side) with respect to the lines they form. In other words, the main dimension of each cell, i.e., the length, is substantially orthogonal to the main direction of the line, i.e., the direction of circulation of the current. The long sides of two adjacent cells are parallel. The electrolytic cells or pots can implement various technical variations that do not form part of the present invention, and such pots are already known to those skilled in the art. Only the outline of the metal (steel) shell outside the cell, i.e., the "pot shell", is shown in FIG. 1.

[0046] The general structure of the electrolytic cell itself in the Hall-Héroult process is known and will not be described in detail here. In particular, with reference to FIG. 2, it is sufficient to explain that a typical cell 1 includes a pot shell that includes a first longitudinal side wall 2, a second longitudinal side wall 2', first and second transverse end walls (not shown in FIG. 1), and a bottom 4. The walls of the pot shell, together with the cathode blocks 8, define a space lined with refractory material (to maintain the heat balance during the electrolysis process) on the bottom and sides, thereby defining a volume that contains the molten metal and the electrolyte. The side lining 3 is composed of a layer of carbonaceous material (not shown in the figure) that is protected by a solid electrolyte that contacts the molten liquid material during steady-state operation.

[0047] The cathode blocks 8 include one or more cathode collector bars 9. They project from the pot shell. A plurality of anode assemblies 5 are also provided, each of which includes an anode rod 6 and an anode 7. The current enters the cell through the anode 7 (which is suspended above the cell by an anode rod 6 attached to an aluminum beam called an anode beam and supported by an upper cell structure 10), passes through the molten electrolytic bath 11 and the molten aluminum pad 12, and enters the carbon cathode blocks 8. The current exits the cell through the cathode collector bars 9 connected to a cathode bus bar not shown in FIG. 2. The cell 1 is closed by a set of hood panels 13. By a well-known method, the anode rod can be removably fixed to the anode beam by the clamp 14 shown schematically.

[0048] Generally, all the tanks in the plant have the same structure. Two buildings 16, 16' are also provided to cover each line. In Figure 1, these buildings are shown by virtual lines. As shown in Figures 3 and 4, the buildings 16, 16' include side walls 17, 18 and an upper wall 19. The buildings 16, 16' can open and close one or both longitudinal ends. Referring to these figures, each tank is arranged to leave running paths 20, 21 on the inner surfaces of the side walls 17, 18 of the buildings 16, 16'. These paths enable the movement of the anode maintenance device along the main axis of each line as described later. Each path is provided with appropriate means such as rails for cooperating with complementary means of the anode maintenance device such as wheels.

[0049] The combination in the present invention, namely, on the one hand, a heavy object lifting device (cathode transfer crane, often abbreviated as CTC for short) and / or a pot tending assembly (abbreviated as PTM for short), and on the other hand, at least one anode maintenance device, will be described below. In particular, it is advantageous for the anode maintenance device to use the same running path as the heavy object lifting device and / or the pot tending assembly. When there is no need for a machine to lift heavy objects, the machine does not stay in the line and is placed (usually) in a pot repair area (not shown in the figure), and is then moved from there to the pot line by a conveying machine (not shown in the figure) usually arranged in the central passage. This description will be made first with reference to Figures 3 to 6 which are schematic diagrams. The structure of these anode maintenance devices will be described in more detail with reference to Figures 7 and later.

[0050] The plant according to the present invention is provided with a pot tending assembly 25 schematically shown in FIG. 3. The latter comprises an elongate body 26 as a beam provided with the above-described complementary means so as to travel along the above-described path. Further, the pot tending assembly is provided with a so-called pot tending machine 27. As is known in this way, this lifting machine is configured to perform a function of lifting an anode beam. In this regard, the lifting force of this lifting machine is sufficient to achieve this lifting. Usually, this lifting machine is not configured to perform other functions such as replacing a used anode assembly with a new anode assembly, and although it is possible to add a specific anode exchanger to the pot tending machine, unnecessary costs are added and sufficient freedom of use cannot be obtained.

[0051] The plant according to the present invention is usually also provided with a heavy object lifting device (not shown in the figure), and this heavy object lifting device comprises an elongate body such as a beam provided with the above-described complementary means so as to be able to travel along the above-described path. Further, the heavy object lifting device is provided with a so-called heavy object lifting machine, and this heavy object lifting machine is configured to perform a function of lifting a pot shell and lifting an upper structure by a known method. In this regard, the lifting force of this lifting machine is sufficient to achieve this lifting. Usually, this heavy object lifting machine is not configured to perform other functions such as a pot tending function (lifting of an anode beam, etc.) or an anode maintenance function.

[0052] The plant according to the present invention is also provided with at least one so-called anode maintenance device. In this embodiment, as will be described in more detail, two anode maintenance devices 30, 35 are provided. Each anode maintenance device schematically shown in FIG. 4 comprises an elongate body 31 such as a beam provided with the above-described complementary means so as to travel along the above-described path. Further, the anode maintenance devices 30, 35 are provided with a so-called anode maintenance machine 32. The present invention relates to the anode maintenance devices 30, 35 and the anode maintenance machine 32.

[0053] This machine 32 is provided with several operation devices, which will be described in more detail later. These operation devices are configured to perform specific anode maintenance functions, such as replacing a used anode assembly with a new one. These operation devices are not configured to lift the tank or raise the anode beam. In this regard, the lifting force of each operation device is not sufficient to achieve this lifting. Usually, the lifting force of each of these operation devices is less than 20 tons, and may be less than 10 tons. This simplifies the structure.

[0054] In other words, the heavy object lifting machine is configured to realize specific functions, such as lifting the entire tank or the upper structure that cannot be realized because the lifting force of the anode maintenance machine 32 is insufficient. Similarly, the pot tending machine is configured to perform specific pot tending operations that cannot be executed because the anode maintenance machine 32 does not have sufficient lifting force. Furthermore, the anode maintenance machine 32 is configured to perform at least one so-called unique function that cannot be automatically executed by the pot tending machine, such as automatically (i.e., without a human operator) replacing a used anode assembly. On the other hand, the heavy object lifting machine of the heavy object lifting device is not suitable for replacing a used anode assembly with a new one because there is no specific tool.

[0055] Next, with reference to FIGS. 5 and 6, the operation method of the global plant according to the present invention will be described. However, these do not show the operation of the anode maintenance devices 30 or 35, which will be described with reference to FIGS. 10 to 18.

[0056] Depending on the number of tanks targeted, it is advantageous to provide a plurality of anode maintenance devices in each line of the plant. FIGS. 5 and 6 show a first anode maintenance device 30, 30' and a second anode maintenance device 35, 35' for enabling the replacement of anodes simultaneously in different tanks of the same tank line.

[0057] Referring to FIG. 5, assume that the pot tending assemblies 25, 25' face one first predetermined cell Ci, C'i located near the rectifier end of the line in the said figure. As a variant, the pot tending assembly may be arranged between two adjacent cells. In particular, this pot tending assembly can perform a first type of operation on the cell, such as lifting the cell. In this regard, all other cells can be handled by two anode servicing devices. In fact, the upper cells C1 to Ci-1, C'1 to C'1-1 are handled by the first anode servicing devices 35, 35', while the lower cells Ci+1 to Cn, C'i+1 to C'n are handled by the second anode servicing devices 30, 30'.

[0058] Referring to FIG. 6, assume that the pot tending assemblies 25, 25' have moved from the position in FIG. 5 and face a second predetermined cell Cj, C'j located near the non-rectifier end of the line in the said figure. According to the present invention, all other cells can still be handled by two anode servicing devices. In fact, the upper cells C1 to Cj-1, C'1 to C'j-1 are handled by the first anode servicing devices 35, 35', while the lower cells Cj+1 to Cn, C'j+1 to C'n are handled by the second anode servicing devices 30, 30'.

[0059] In the context of the present invention, the first and second anode servicing devices 30, 30', 35, 35' can perform servicing operations on the cells, and these servicing operations may be the same or different servicing operations. In particular, it may be necessary to proceed with the work of replacing the used anodes with new ones. With reference to FIGS. 7 to 18, one structural embodiment of an anode servicing machine capable of such replacement is described.

[0060] An overall view of the anode servicing machine 30 according to an advantageous embodiment is shown in FIG. 7. The elongate body 31 of the anode servicing machine 30 particularly includes two parallel rails 33, 33' extending along the transverse axis YY. As a result, this axis coincides with the so-called main axis L31 of the elongate body 31 particularly shown in FIG. 8.

[0061] As shown in FIG. 8, each of the rails 33, 33' includes opposing upper and lower walls, and opposing inner and outer walls. The so-called inner wall of one rail faces the other rail. The tracks 34, 34', 34'' are provided on at least one side wall of at least one rail. The structure of the track is of any suitable type and enables the movement of the carriers described below. In the illustrated example, tracks corresponding to both the inner and outer walls of the first rail are provided, and a corresponding track is provided on the outer wall of the second rail.

[0062] Returning to FIG. 7, each of the tracks 34, 34', 34'' cooperates with at least one carrier 40, 50, 60, 70, 80, 81, 90, 91 mounted on the track. The carrier is movable along the main axis L31 of the elongate body 31 on the track. For this reason, the carrier is provided with suitable traveling means such as rolling means. Each of the carriers 40, 50, 60, 70, 80, 81, 90, 91 is configured to support one or more operating devices 45, 55, 65, 75, 85, 95. In the example of FIG. 7, two carriers 90, 91 are provided on the outer wall of the first rail 33, three further carriers 40, 50, 70 are provided on the inner wall of the first rail 33, and three further carriers 60, 80, 81 are provided on the outer wall of the second rail 33'.

[0063] The carrier can cooperate with the above-described operating device in two different modes. In the first mode, one carrier may directly form the support assembly of each operating device. In other words, it means that a given operating device is fixed to the carrier, at least with respect to movement. In the present embodiment, this applies to the two carriers 40, 50 that support the hopper 45 and the nozzle 55 respectively, and their functions will be described in detail later.

[0064] In this first mode, the operating devices 45, 55 are independently movable only along the longitudinal axis L31 of the elongate body 31. In the second mode, some carriers may support the operating devices while allowing further movement of the device. In this regard, an intermediate platform is fixed on the carriers, and the platform enables movement of the device along the vertical axis ZZ. This axis is shown in FIG. 9. For this purpose, the platform is equipped with appropriate driving means such as a servo motor. And the support assembly in the sense of the present invention is formed by the carriers and the platform.

[0065] According to a first case in the second mode, a single carrier 60 cooperates with a single platform 62 that supports an operating device which is a bucket shovel 65. Similarly, a single carrier 70 cooperates with a single platform 72, and the single platform 72 supports an operating device which is a first robot 75. The structure of this operating device will be described in more detail below.

[0066] According to a second case in the second mode, especially when the operating device is heavy and large in size, two different carriers may be provided for one single operating device. As shown in FIG. 7, two carriers 80 and 81 respectively support two platforms 82 and 83, on which a first lifting robot 85 is arranged. Additionally, another two carriers 90 and 91 respectively support two platforms 92 and 93, on which a second lifting robot 95 is arranged. The lifting robots 85 and 95 are usually adapted to lift anodes in a well-known manner.

[0067] In this second mode, the operating devices 65, 75, 85, 95 can move independently not only along the longitudinal axis L31 of the elongated body 31 but also along the vertical axis ZZ. The functions of these mechanical elements will become clear by reading the following description of the embodiments of the operating method according to the present invention. This example is further shown with reference to FIGS. 10 to 17. In the latter, not all of the mechanical elements of the device for anodic dressing according to the present invention are shown for clarity. In particular, FIGS. 10 to 17 show only one of the two rails 33 forming the elongated body.

[0068] These figures show the robot 75 in more detail. Referring particularly to FIG. 12, this robot 75 first starts from a platform 72 and includes a deck 750 rotatably mounted on this platform about a vertical axis. Further, three consecutive arms are provided, namely, a proximal arm 752 rotatably mounted on the deck 750 about a horizontal axis A752, an intermediate arm 753 rotatably mounted on the arm 752 about a horizontal axis A753, and a distal arm 754 rotatably mounted on the arm 753 about a horizontal axis A754. A rotor 756 is rotatably mounted about the longitudinal axis L754 of the distal arm. The rotor is provided with a multi-purpose head 758 rotatably mounted about a horizontal axis A758. As particularly shown in FIGS. 13 and 14, this head is configured to removably accommodate specific tools 77, 78, and 79 described later. In particular, these tools can be removably fixed to the platform 72. Further, this head 758 is provided with a camera 76 of any suitable type, particularly a 3D type. Unlike the tools 77 to 79, this camera is preferably fixedly attached to this head.

[0069] If it is necessary to replace one of the anode assemblies of the cell, this assembly is hereinafter referred to as the "used anode assembly". The latter is referenced by 5U, and its rod and anode are indicated by 6U and 7U respectively. This task is performed by the first or second anode servicing device. Assume that the selected anode servicing device is referenced by 30. The latter first picks up a so-called replacement anode assembly for replacing the used anode assembly described above. In this regard, FIG. 10 shows the end cell C1 and a group RG of replacement anode assemblies gathered near this cell C1. Next, the anode servicing device 30 moves to the group of replacement anode assemblies by traveling along the travel paths 20, 21 shown in FIGS. 3 and 4. FIG. 10 shows the rails 33 of the anode servicing device 30, one of these travel paths 20, and the robots 75 and 85.

[0070] It should be noted that 5R is the selected replacement anode assembly, and 6R and 7R are its rod and anode respectively. The 3D camera 76 first identifies the position of the replacement anode rod 6R (see capture 76A). Next, the lifting robot 85 moves, first picks up the replacement anode assembly, and then, as shown in FIG. 11, lifts the picked-up assembly (see arrow L1). When this replacement anode assembly is lifted, the 3D camera identifies the position of this replacement anode (see capture 76B). After this decision step, the anode servicing device 30 carrying the replacement anode assembly 5R is returned along the travel path until it reaches the position of the used anode (see arrow F30 in this FIG. 11).

[0071] Next, the robot 75 is moved to equip its head 758 with a U-shaped gripper 77 (see FIG. 12). This gripper 77 is removably fixed to the platform 72 (see in particular FIG. 14 showing this gripper on this platform) and is configured to cooperate with the hood panel 13. As shown in FIG. 12, each anode assembly in a specific tank is associated with two adjacent hood panels. That is, to access a specific anode assembly, it is necessary to remove two adjacent hood panels. In particular, the used anode assembly 5U is associated with the hood panels 13A and 13B. The camera 76 first identifies the position of the right hood panel 13A, and then the gripper 77 lifts the hood panel and places it on the adjacent hood panel 13C as shown in FIG. 12. The same operation (not shown in this FIG. 12) is also performed on the left hood panel 13B, the left hood panel 13B is identified, grasped, and placed on the adjacent hood panel 13D.

[0072] Next, the robot 75 is moved and the gripper 77 on the platform is released. The head 758 is equipped with the nozzle 55 described above. This nozzle enables the suction of a high-temperature material (a mixture of a pulverized bath and alumina) called ACRM (Anode Cover Recycled Material) from the vicinity of the used anode along the arrow F55. This step is shown in FIG. 13. Next, the nozzle is returned onto the carrier 50.

[0073] Thereafter, the robot 75 is further moved and its head is equipped with a crust saw 78 that is removably supported by the platform 72 (see also FIG. 13 showing this saw attached to this platform). Next, the outer shell around the used anode is broken, usually around the four sides of the used anode (see FIG. 14 including the line F78 showing the movement of the saw 78). To avoid excessive damage, the 3D camera has previously identified the positions of the adjacent anodes, that is, the positions of the anodes on both sides of the used anode. Next, the crust saw 78 is returned onto the platform 72.

[0074] Thereafter, the position of the anode rod 6U of the used anode assembly 5U is checked using the 3D camera 76. This step, although not shown in the figure, is the same as the above-described steps performed on the replacement anode assembly 5R. Next, another lifting robot 95 descends to come near the used anode assembly. The clamp 14 is unlocked using a suitable screw tool 96 provided on the lifting robot 95. Next, as shown by the arrow L2 in FIG. 15, the latter lifts the used anode.

[0075] The 3D camera 76 determines the position of this used anode, as shown in FIG. 16 (see capture 76C). FIG. 16 shows, on the one hand, the lifting robot 85 and the replacement anode assembly 5R, and on the other hand, the lifting robot 95 and the used anode assembly 5U. It should be noted that special advantages are obtained by providing two different lifting robots 85, 95. In fact, this enables the simultaneous operation of the two anode assemblies without moving the anode maintenance device between the group of the used anode assembly and the replacement anode assembly. This makes it possible to save the time required for the overall processing of the plant.

[0076] The camera 76 also checks the shape of the used anode assembly 5U and the position of the pot opening PO created by removing the hood panels 13A and 3B. In FIG. 17, only the panel 13A removed first is shown on the panel 13C, but note that the other removed panel 13B is arranged on the panel 13D. Next, the replacement anode assembly 5R is placed inside the above-mentioned pot opening. This step is shown in FIG. 17, and the arrow D indicates the downward movement of both the robot 85 and the replacement anode assembly 5R. The final position of the replacement anode is adjusted based on the image captured by the above-mentioned camera 76 as described above. The clamp 14R is locked by a tool 86 similar to the tool 96 provided on the robot 85.

[0077] As shown in FIG. 18, the multi-purpose head 758 of the robot 75 grips the above-described nozzle 55. The latter contains the amount of recycled hot ACRM poured near the replacement anode along the arrow f55. Further, cold ACRM is further poured onto the poured ACRM until it reaches an appropriate thickness (this step is not shown). This additional amount of ACRM is supplied from the hopper 45 to the nozzle 55.

[0078] As a final step, although not shown either, the multi-purpose head of the robot 75 returns the hood panels 13A and 13B to their original positions so as to close the pot opening PO. The camera 76 checks whether the new anode is at the appropriate height. As a further confirmation step, a multi-purpose head gripping tool 79 configured to measure the strength of the current and determine the appropriate anode setting is used.

[0079] It should be noted that the embodiment of the anode preparation device according to the present invention, which includes a camera configured to determine and control the height of the anode, is particularly advantageous. In conventional devices, either an external reference system or a laser height measurement device is used.

Claims

1. Anode maintenance equipment (30, 35) for an aluminum electrolysis plant, The aluminum electrolytic plant comprises at least one line (L1, L2) of electrolytic cells (C1 to Cn, C'1 to C'n) connected in series, Each tank is connected to a cathode busbar, and each tank has multiple anode assemblies (5) connected to an anode beam. The aforementioned anode maintenance device is A slender body (31) as a beam, A traveling means configured to allow the elongated body to move along a direction substantially parallel to the main axis of the lines (L1, L2), The system includes an anode maintenance machine (32) attached to the elongated body, The aforementioned anode maintenance machine is The system includes at least two operating devices (45, 55, 65, 75, 85, 95), each configured to perform at least one specific anode maintenance function, wherein the anode maintenance function is different from lifting the tank and raising the anode beam. Includes at least two support assemblies (40, 50, 60, 62, 70, 72, 80, 81, 82, 83, 90, 91, 92, 93), each configured to support the respective operating device on the elongated body, An anode maintenance device wherein the operating devices (45, 55, 65, 75, 85, 95) are movable independently of each other along at least one of the longitudinal axis (L31) and the vertical axis (ZZ) of the elongated body (31).

2. A device for maintaining an anode according to claim 1, At least one of the support assemblies is The elongated body is provided with at least one carrier (40, 50) that is movable relative to the elongated body along its main axis (L31), An anode maintenance device wherein each of the aforementioned operating devices (45, 55) is fixed to the carrier, at least in terms of movement.

3. A device for maintaining an anode according to claim 1 or 2, At least one of the support assemblies is At least one carrier (60, 70, 80, 81, 90, 91) that is movable relative to the elongated body along its longitudinal axis, Anode maintenance apparatus, comprising at least one drive member (62, 72, 82, 83, 92, 93) having a drive means configured to move the operating device relative to the carrier along the vertical axis (ZZ).

4. A device for maintaining an anode according to claim 3, At least one of the support assemblies comprises two of the carriers (80, 81, 90, 91) and two of the drive members (82, 83, 92, 93), An anode maintenance device, wherein the drive means is configured to move a single operating device relative to the carrier along the vertical axis.

5. A device for maintaining an anode according to claim 1 or 2, The elongated body (31) comprises at least one, and in particular at least two, parallel rails (33, 33'), Anode maintenance device, wherein at least one rail is provided with at least one track (34, 34', 34'') for the movement of at least one carrier.

6. A device for maintaining an anode according to claim 1 or 2, At least one specific anode maintenance function is Lifting a new anode, Cleaning the anode cover material surrounding and / or covering the anode by suction. Cutting the hard coating material surrounding the anode with a saw. Lifting the spent anode, To position a new anode at a specific height, Adding anode cover material on and around the anode, Record an image representing the position and shape of the anode. Move the hood panel to allow access to the anode. Anode maintenance equipment, which is selected from the following: and the process of returning the hood panel after the anode replacement is complete.

7. A device for maintaining an anode according to claim 1 or 2, An anode maintenance apparatus in which the lifting force of each of the aforementioned operating devices is less than 20 metric tons, preferably less than 15 metric tons, and more preferably less than 10 metric tons.

8. A device for maintaining an anode according to claim 6, It is equipped with at least two so-called lifting operation devices (85, 95), An anode maintenance apparatus in which each of the aforementioned lifting operation devices is configured to lift each anode assembly (6, 106).

9. A device for maintaining an anode according to claim 6, Equipped with a so-called multi-purpose operating device (75), The multi-purpose operating device is provided with a head (758), Anode maintenance apparatus, wherein the head is configured to work in conjunction with a tool (55) detachably fixed to a separate operating device, and / or tools (77-79) detachably fixed to a multi-purpose operating device.

10. An aluminum electrolytic plant comprising at least one line of electrolytic cells having a substantially rectangular shape, The plant further comprises means for electrically connecting the tanks in series, and means for connecting the cathode busbar of one tank to the anode beam of a downstream tank. The plant comprises at least one heavy lifting device and / or at least one pot tending assembly (25), If the aforementioned heavy lifting device exists, A slender body as a beam, A traveling means configured to move the elongated body along a traveling direction substantially parallel to the main axis of the line, The system includes a heavy lifting machine (27) attached to the elongated body, configured to perform at least one function of a so-called heavy lifting type, including lifting a pre-lined pot shell, a pot shell with damaged lining, and a superstructure, If the potting assembly (25) is present, A slender body as a beam, A traveling means configured to move the elongated body along a traveling direction substantially parallel to the main axis of the line, The system includes a pot tending machine (27) attached to the elongated body and configured to perform at least one so-called main type function, including raising and tapping the anode beam, The line of the plant is further characterized by including at least one anode maintenance device (30, 35) according to any one of claims 1 to 9, The anode maintenance devices (30, 35) are as follows: The main body (31) and A driving means configured to enable movement along the direction of travel of the main body, The system comprises an anode maintenance machine (32) attached to the main body and configured to perform at least one specific anode maintenance function, Furthermore, at least one of the heavy lifting type functions and / or at least one of the main type functions is different from the specific anode maintenance function. On the other hand, at least one of the specific anode maintenance functions is different from the heavy lifting type function and the main type function, in particular from tank lifting, anode beam raising and tapping, in an aluminum electrolytic plant.

11. The aluminum electrolytic plant according to claim 10, The anode maintenance device (30, 35) comprises a travel means and at least one common travel path (20, 21) configured to cooperate with the travel means of the heavy lifting device and / or the pot tending assembly, In particular, an aluminum electrolytic plant having two common travel paths provided on both sides of the tank with respect to the horizontal axis of the line.

12. A method for operating the anode maintenance device (30, 35) according to claim 1 or 2, The anode maintenance device is particularly part of the aluminum electrolytic plant described in claim 10 or 11, The aforementioned operating method is: A step of lifting a so-called replacement anode assembly (5R) with a first lifting operation device (85) of the anode maintenance device, wherein the replacement anode assembly is for replacing a so-called used anode assembly (5U), A step of moving the anode maintenance device that carries the replacement anode assembly near the used anode assembly, The process involves lifting the used anode assembly using the second lifting device (95) of the anode maintenance apparatus, The process includes placing the replacement anode assembly in the original location of the used anode assembly, The aforementioned operating method is further advantageous in that, A step of analyzing the shape of the used anode and determining the height position of the replacement anode, and / or, A method for operating an anode maintenance apparatus, comprising the steps of vacuum cleaning the material around a used anode assembly, storing at least a portion of the material, and pouring at least a portion of the stored material around a replacement anode assembly.

13. A method for operating an aluminum electrolytic plant according to claim 10 or 11, The heavy lifting assembly or the pot tending assembly (25) is positioned above one predetermined tank of the plant or between two adjacent tanks, and the first anode maintenance device (30) is positioned above the first tank located on the first side of the predetermined tank or the two adjacent tanks with respect to the main shaft, and / or The second anode maintenance device (35) is positioned on a second tank located on the second side of the predetermined tank or the adjacent tank with respect to the main shaft, The aforementioned operating method is further advantageous in that, A method for operating an aluminum electrolytic plant, comprising performing at least one specific anode maintenance function on the first tank and / or performing at least one specific anode maintenance function on the second tank.

14. A method for producing aluminum by the Hall-Héroult electrolysis, A method for producing aluminum, characterized by being carried out in an aluminum electrolytic plant according to claim 10 or 11.

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