Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium

Definitions

• the invention relates to plants for the production of aluminum by igneous electrolysis according to the Hall-Héroult process. It particularly concerns the location of the facilities of such factories.
• Aluminum metal is produced industrially by igneous electrolysis, namely by electrolysis of alumina in solution in a molten cryolite bath, called electrolysis bath, according to the well-known Hall-Héroult process.
• the electrolysis bath is contained in tanks comprising a steel box, which is coated internally with refractory and / or insulating materials, and a cathode assembly located at the bottom of the tank.
• Anodes made of carbonaceous material are partially immersed in the electrolysis bath. Each cell and its anodes form what is often called an electrolysis cell.
• the electrolysis current which circulates in the electrolysis bath and the sheet of liquid aluminum via the anodes and cathode elements, operates the alumina reduction reactions and also makes it possible to maintain the bath. electrolysis at a temperature of the order of 950 ° C by the Joule effect.
• the most modern factories contain a large number of electrolysis cells arranged in line, in buildings called electrolysis halls, and electrically connected in series using connecting conductors, so as to optimize the occupation on the ground. factories.
• the tanks are generally arranged so as to form two or more parallel rows which are electrically linked together by end conductors.
• the electrolysis current thus cascades from one cell to the next.
• the length and mass of the conductors are as small as possible so as to limit the corresponding investment and operating costs, in particular by reducing losses by Joule effect in the conductors.
• the conductors are also configured to reduce or compensate, in whole or in part, for the effects of magnetic fields produced by the electrolysis current.
• an electrolysis plant comprises a series of flows, including in particular flows of raw materials (alumina, carbon powder, pitch), flows of intermediate products (solidified bath crusts, anode assemblies, etc.), flows of final products (liquid and / or solid aluminum), flows of personnel (pedestrians or drivers of self-propelled machines), flows of energy (in particular flows of electrical energy), flows of demolition products (in particular anode baking ovens), tooling flows, flow of tank components (such as cathodes or boxes) and maintenance material flows. Certain flows are essentially continuous (such as the flows of raw materials), others are quasi-continuous (such as the flows of liquid aluminum, of anode assemblies and of solidified bath) and others are essentially discontinuous (such than cathode or box flows).
• raw materials alumina, carbon powder, pitch
• flows of intermediate products solidified bath crusts, anode assemblies, etc.
• flows of final products liquid and / or solid aluminum
• flows of personnel pedestrians or drivers of self-propelled machines
• flows of energy in particular flows of electrical
• the Hall-Héroult process involves the consumption of carbon anodes during electrochemical reactions to reduce alumina; this consumption requires the regular supply of new anodes and the replacement of the used anodes of the electrolysis cells, which generates flows of new anode assemblies from the anode manufacturing sites to the electrolysis cells and flows of assemblies anode spent from tanks to reprocessing and recycling sites.
• the Applicant has therefore sought factory arrangements which take account of the various constraints, which lead to a reduction in investment and maintenance costs, and which make it possible to increase the production capacity of the factory.
• the subject of the invention is an arrangement of an electrolysis plant for the production of aluminum according to the Hall-Héroult process, said plant comprising at least one liquid aluminum production zone (H), which is characterized in that it comprises:
• heavy intermediate products such as liquid aluminum, anode assemblies and solid electrolysis bath
• the arrangement according to the invention therefore allows both an optimization of the distances traveled by the main heavy flows of an electrolysis plant, which are potentially at risk, and a consideration of the effects of physical interactions between the flows and facilities.
• Figures 1, 2, 3, 6a, 7a, 8a, 9a and 10a relate to the prior art.
• Figures 4, 5, 6b, 7b, 8b, 9b and 10b relate to the invention.
• Figure 1 illustrates an arrangement of a prior art electrolysis plant.
• Figure 2 illustrates an electrolysis hall in cross section along the plane NN of Figure 1.
• Figure 3 illustrates an electrolysis cell in cross section along the plane BB of Figure 2.
• Figure 4 illustrates an arrangement of an electrolysis plant according to the invention.
• FIG. 5 illustrates an embodiment of the reserved traffic zones according to the invention.
• Figures 6 to 10 illustrate the flows of anode assemblies (Figure 6), liquid and solid bath (Figure 7), liquid metal (Figure 8), raw materials and final products (Figure 9) and personnel ( Figure 10) in the prior art plant shown in Figure 1 ( Figures 6a, 7a, 8a, 9a and 10a) and in a factory arrangement according to the preferred embodiment of the invention shown in Figure 4 ( Figures 6b, 7b, 8b, 9b and 10b).
• the prior art electrolysis plants typically comprise a zone for the production of liquid aluminum (H), which comprises electrolysis cells normally arranged in series (not shown), facilities for the provision and recycling of anode assemblies (11, 12, 13, 14, 15, 16), facilities for the provision and recycling of electrolysis baths (13, 14, 15, 17), installations for processing liquid aluminum (20, 21, 22) and installations intended for the maintenance of production equipment (31, 32, 33, 34, 35) and at least one administrative building (36).
• the facilities for the provision and recycling of anode assemblies, the facilities for the provision and recycling of electrolysis baths, and the facilities for processing liquid aluminum are generally located in areas isolated from the factory; on the other hand, the installations intended for the maintenance of the production equipment and the administrative buildings are distributed throughout the factory.
• the liquid aluminum production zone (H) typically comprises an even number of electrolysis halls (1), generally two or four halls arranged in parallel, means for supplying electricity to the electrolysis cells (2), means for supplying alumina (3, 4), means (5) for treating the gases emitted by the process, circulation paths (6) parallel to the electrolysis halls and means of access (7) to the halls electrolysis.
• the electrolysis halls may include one (or more) transfer hall (s) (8) to facilitate the movement of personnel and possibly the transport of certain equipment and tools.
• Each electrolysis hall (1) comprises at least one row of electrolytic cells (not shown), the number of cells in a row possibly being greater than a hundred.
• the facilities for providing anode assemblies most often include means for supplying raw materials (1 1, 16), facilities for manufacturing anode blocks, assembling anode assemblies and recycling spent anodes (12, 13), and access means (14).
• the installations intended for the manufacture of the anode blocks (12) include in particular the means for shaping the raw anodes and the means for cooking them (typically comprising a rotary fire oven).
• the anode assembly recycling facilities (15) include means for separating the anodes and anode rods, and means for grinding the used anode blocks for recycling in the production of new anode blocks.
• Liquid aluminum treatment plants (20, 21, 22) typically include a foundry and access means (21). Maintenance and servicing facilities for production equipment are generally in separate buildings (31, 32, 33, 34, 35) located on the plant site. The factory is traversed by traffic lanes (6, 61, 62, 63).
• an electrolysis hall (1) typically comprises a roof (71), a series of cells (40), a circulation aisle (10) along the cells and a movable bridge (70 ) to carry out operations on the tanks.
• a tank (40) typically comprises a metal box (41) lined internally of refractory materials (42a, 42b), cathode assemblies in carbon material (43), anode assemblies (55), a support structure (53), means (51) for recovering the effluents emitted by the tank in operation and means (50) for supplying alumina and / or N1F 3 to the tank.
• the anode assemblies (55) typically include an anode block (47a, 47b) and a rod (49a, 49b). Each rod (49a, 49b) typically comprises a multipod (48a, 48b) for fixing the anode block (47a, 47b).
• the tank comprises a liquid aluminum bed (44), a liquid bath bed (45) and a cover (46) based on solid bath and alumina.
• the program for changing the anode sets is generally designed in such a way that they have a different degree of wear (in Figure 3, the anode block ( 47a) is less used than the anode block (47b)).
• the electrolysis current flows from the anode blocks to the cathode elements.
• the cathode current is recovered by conductive bars (52).
• FIGS 6a, 7a and 8a respectively show the flows of anode assemblies (FC1, FC2), solid bath (FBI, FB2, FB3, FB4) and liquid aluminum (FN1, FN2) from a factory in the prior art.
• Solid bath streams include two components: so-called “before treatment” bath streams (FBI, FB2) (in bold lines), which come in particular from excess bath extracted from the electrolytic cells, and so-called “bath streams” ground “(FB3, FB4) (broken lines), which correspond to the reprocessed bath.
• FBI before treatment bath streams
• FB2 bath streams
• ground ground
• these heavy flows generally circulate by tracks (6) which are also regularly used by the staff.
• these flows are complex and include mass movements between the internal and external parts of the electrolysis halls (1) and bypass paths (FC2, FB2, FB3, FN2).
• FC2, FB2, FB3, FN2 bypass paths
• these flows circulate by internal (10) and external (6) routes to the buildings which house the rows of tanks, and include numerous entry and exit movements via access routes (7).
• the arrangement of an electrolysis plant for the production of aluminum according to the Hall-Héroult process comprising at least one zone for the production of liquid aluminum (H) comprising electrolytic cells arranged in rows, facilities for the provision and recycling of anode assemblies, facilities for the provision and recycling of electrolysis baths, facilities for processing liquid aluminum, is characterized in that it includes: - operational areas of specific stewardship including an area (C) where the facilities for the provision and recycling of anode assemblies are grouped, an area (B) where the facilities for provision and recycling are grouped together of electrolysis bath and an area (N) where the liquid aluminum treatment plants are grouped, - means of transport for transporting so-called heavy intermediate products between said zo nes operational, according to determined intermediate flows (HC1- HC7 HB1-HB12, HN1-HN7), said intermediate products including in particular liquid aluminum, anode assemblies and solid electrolysis bath, - at least one circulation zone (101, 102, 103, 104, 105, 106
• reserved traffic areas will also designate the case where there is only one reserved traffic area.
• the reference “100” collectively designates the different reserved traffic areas (101, 102, 103, 104, 105, 106, 110, 111, 112, 113).
• At least one given heavy intermediate product is preferably entirely conveyed in at least one circulation zone which is reserved for it.
• the main heavy intermediate products namely liquid aluminum, anode assemblies and the solid electrolysis bath, are entirely transported in at least one reserved circulation zone. It is particularly advantageous that at least one reserved circulation area (101, 102, 1 10, 1 1 1, 1 12, 1 13) is common to at least two separate heavy intermediate products.
• the reserved circulation areas (100) are preferably specifically equipped for the circulation of said heavy flows.
• the arrangement according to the invention can also include channels (9) which give access to different parts of the installations and allow their maintenance.
• At least one operational area called “maintenance” stewardship (E) can group all or part of the maintenance and maintenance operations, and preferably all of these operations.
• at least one operational area of stewardship called “administration” (D) can group all or part of the administrative operations, and preferably all of these operations.
• the administration area can include facilities for managing flows and / or controlling the quality of intermediate products.
• the arrangement according to the invention advantageously comprises at least one operational maintenance area (E) and at least one operational administration area (D).
• the reserved traffic areas (100) are preferably located on one level.
• they can be located at the side aisles (10) of the halls electrolysis (1). They may possibly include several levels. For example, part of said zones can be located at said side aisles (10) and another part can be located at ground level (80) outside the electrolysis halls (1). They may possibly include superimposed levels. For example, they can include a level at the side aisles (10) and a level (72) located below these, each level can be used for transporting different flows.
• At least one reserved circulation zone (101, 102, 103) connects at least two of said operational zones, preferably at least three operational zones, and possibly all of them, which allows the efficient circulation of heavy flows by the reserved lanes between said operational zones.
• At least one reserved circulation area (101, 102), called “transverse”, is substantially perpendicular to said rows of electrolytic cells, as illustrated in FIG. 5.
• at least one reserved circulation area (101, 102), called “main” passes substantially through the barycenter of the (or each) liquid aluminum production area (H).
• the area for the provision and recycling of anode assemblies (C), the area for the provision and recycling of the electrolysis bath (B), the area for processing liquid aluminum (A), and, possibly, the maintenance zone (E), are connected to the (or each) liquid aluminum production zone (H) by at least one reserved transverse and / or main circulation zone (101, 102, 103 ).
• a single transverse and / or main circulation zone which makes it possible to limit the investments and to better control the flows.
• At least one reserved circulation area (1 10, 1 11, 1 12, 1 13), called “lateral”, can optionally run along said rows of electrolysis cells, advantageously inside the electrolysis halls (1) .
• These lateral zones may possibly be located on the circulation aisles (10) on other levels (72).
• the arrangement according to the invention further comprises at least one specific covering building (121, 122) to house certain reserved traffic areas, such as certain transverse areas (101, 102). Roof buildings avoid the problems typically associated with the formation of ice, rain, temperature or humidity.
• the reserved traffic areas (100) may include specific means of transport dedicated to heavy flows between the operational areas, in particular between the electrolysis halls and the stewardship areas (A, B, C, D, E). These means advantageously include shuttles for transporting and depositing specific items such as:
• the means of transport can make it possible to limit the intermediate storage areas, such as those normally provided for cooling the anodes or for the pockets of liquid metal. They can also allow just-in-time handling, in particular in the variants of the invention providing for automated operations.
• the heavy flows according to the invention may nevertheless include intermediate storage areas.
• the means of transport are advantageously associated with handling means.
• the means of transport can include conveyors, which have the advantage of being easily automated, or self-propelled machines, which are possibly driven by personnel.
• Said means of transporting intermediate products according to heavy flows can comprise a network on rails.
• These rails can advantageously be located outside the heavy structures of the electrolysis buildings, ensuring the connection between the or each production zone and the other operational zones of the factory.
• Mobile machines can move on this network in a possibly automated way.
• self-propelled vehicles driven by operators can also move on other specific tracks outside the reserved areas (100), in one or more traffic aisles.
• the electrolysis halls can also include additional means of transport or maintenance.
• each hall may include overhead maintenance cranes which allow the handling of tank casings (before and after relining) and / or superstructures to or from the maintenance workshops.
• the reserved circulation areas (100) can occasionally be used for the transport of heavy equipment, such as mobile bridges or tank casings, which are not part of the regular heavy flows.
• the plant according to the invention may possibly include service machines moving on raceways adjoining the structure of buildings.
• the flows of anode assemblies can comprise several branches (HCl to HC7). Some branches (HCl to HC4) run alongside the tanks electrolysis and circulate preferably inside the halls (1). Common branches (HC5, HC6, HC7) can recover the flows coming from several branches.
• the flows of anode assemblies comprise a branch (HC7) internal to the area for the provision and recycling of anode assemblies (C).
• the flows of new anode assemblies in the direction of the electrolysis cells
• the flows of spent anode assemblies (coming from the electrolysis cells) follow substantially identical paths (but of opposite directions) except inside zone C.
• zone C also includes means for assembling the anode assemblies, from baked anode blocks and recycled or new anode rods, and / or means to separate the anode blocks (worn or defective) and the rods.
• Zone C can include all of the means for manufacturing anode blocks, such as a dough workshop, means for shaping raw anode blocks and a baking oven on a rotating fire. This regrouping allows a compact installation of the installations which leads to a concentration of the operations producing carbon dust, as well as handling and process devices.
• zone C may only include means such as means for handling and storage of the anode blocks.
• the solid bath fluxes can also comprise several branches (HB1 to HB 12).
• the flows include branches (HB1 to HB7) relating to the bath "before treatment” and branches (HB8 to HB12) relating to the bath "ground", that is to say after treatment.
• Certain branches (HB1 to HB4) run alongside the electrolytic cells and preferably circulate inside the halls (1).
• Common branches HB5, HB6, HB7 can recover the flows coming from several branches.
• the electrolysis bath flows comprise a branch (HB7) internal to the area for providing and recycling the electrolysis bath, which is only shown here in a simplified manner.
• the flows of liquid metal can also include several branches (HAI to HA7).
• Certain branches (HA ⁇ to HA4) run alongside the electrolytic cells and preferably circulate inside the halls (1).
• Common branches HA5, HA6, HA7 can recover the flows coming from several branches.
• the liquid metal flows comprise a branch (HA7) internal to the liquid aluminum treatment zone, which is only shown here in a simplified manner.
• the liquid aluminum treatment zone (A) can include a foundry in which the liquid metal can be produced, treated and shaped. According to a variant of the invention in which the foundry means are located in a separate factory, outside the site, the treatment zone (A) may comprise only a reduced number of means, such as handling and loading of liquid metal and, optionally, cooling means.
• the electrolysis plant according to the invention also includes:
• raw materials such as alumina, entry points (El, E2) from the factory to the corresponding operational zones, according to determined entry flows, such as a flow of alumina (FAO) and a carbon flux (FCO);
• the plant according to the invention preferably comprises traffic lanes (6, 61, 62, 63) for personnel who do not intercept the reserved areas (100). Staff move and work inside the electrolysis halls without using the reserved lanes located in the reserved traffic areas. Crossing points between reserved areas and staff traffic areas can be avoided by passageways located at different levels, such as underpasses, walkways, stairs, escalators or elevators.
• Special means of transport can be provided in parallel or overlapping zones, which zones do not intercept the reserved traffic zones.
• ferries can be provided above certain reserved areas in order to transport certain service machines or boxes between the production areas (H) and the maintenance area (E).
• At least one of the heavy intermediate products is entirely transported by at least one automatic vehicle, the or each said vehicle being controlled by at least one central navigation system capable of ensuring the supervision of the quantities and movements of the flows of said heavy intermediate products.
• the invention makes it possible to greatly limit the number of access routes (7) to the electrolysis halls.
• the invention makes it possible to distribute transport more efficiently between the operational zones (or sectors) of the factory. In particular, it allows the bringing together of buildings and the development of synergies between operational areas. It also avoids resorting to large intermediate stocks of raw materials or processed products. It also reduces the risk of transport-related accidents.
• the invention makes it possible to avoid to staff certain repetitive handling tasks and without complexity. In addition, it limits the diversity and number of operations entrusted to operators and service machines, thereby improving the quality and regularity of tank service work, thus also the operational performance of the industrial process in its together.
• the invention also makes it possible to avoid that sophisticated machines, normally provided for the service of tanks are also used for functions of transporting large loads on simple paths, sometimes long distances and at high frequencies. It also avoids the concentration of heavy flow handling inside the electrolysis halls, thereby reducing construction costs and limiting malfunctions, a large part of which is due to the cumulative effects of the various equipment failures or human errors.
• the invention also allows the automation of simple and repetitive tasks, which, in factories of the prior art, are provided by machines which are also used for complicated tasks which are difficult to automate.
• the invention allows a significant reduction in access structures, stairs, walkways and related systems and installations, such as lighting, fire protection, air conditioning / heating and / or communication systems.

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• Chemical Kinetics & Catalysis (AREA)
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• Organic Chemistry (AREA)
• Electrolytic Production Of Metals (AREA)

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