EP0517100B1 - Elektrolysezelle zur Aluminiumgewinnung - Google Patents

Elektrolysezelle zur Aluminiumgewinnung Download PDF

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Publication number
EP0517100B1
EP0517100B1 EP92109006A EP92109006A EP0517100B1 EP 0517100 B1 EP0517100 B1 EP 0517100B1 EP 92109006 A EP92109006 A EP 92109006A EP 92109006 A EP92109006 A EP 92109006A EP 0517100 B1 EP0517100 B1 EP 0517100B1
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EP
European Patent Office
Prior art keywords
anode
blocks
electrolysis cell
cathode
cell according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92109006A
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German (de)
English (en)
French (fr)
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EP0517100A2 (de
EP0517100A3 (en
Inventor
Siegfried Dr. Wilkening
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vereinigte Aluminium Werke AG
Vaw Aluminium AG
Original Assignee
Vereinigte Aluminium Werke AG
Vaw Aluminium AG
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Publication of EP0517100A3 publication Critical patent/EP0517100A3/de
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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
    • C25C3/22—Collecting emitted gases
    • 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
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
    • C25C3/12—Anodes
    • C25C3/125—Anodes based on carbon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/16—Electric current supply devices, e.g. bus bars

Definitions

  • the invention relates to an electrolysis cell for the melt flow electrolytic extraction of aluminum with a continuous anode system using prebaked anode blocks (1, 2), the cathodic current supply being effected via cathode blocks (14, 18) and the aluminum collecting in an aluminum bath at the bottom of the electrolytic cell and a method for using the electrolytic cell in the extraction of aluminum according to the Hall-Heroult principle.
  • An electrolysis cell of the type mentioned is known from DE-B-11 74 517.
  • the currently most advanced, computer-controlled aluminum electrolysis cells work according to this principle with currents of approx. 150 to 30 kA and achieve a specific electrical energy consumption of around 13 kWh per kg aluminum.
  • the anodic current densities of the high-current cells are between 0.65 and 0.85 A / cm 2 .
  • Anodic current densities of over 0.85 A / cm 2 were also used in earlier smaller electrolysis cells. For economic reasons and to maintain the required heat balance, however, a current density of 0.60 A / cm 2 has not been reached.
  • a roof-shaped cathode for electrolytic cells is known from US-A-44 05 433, the material for the cathode consisting of a hard metal, such as silicon carbide, magnesium oxide ceramic.
  • a cathode for a melt-flow electrolytic cell for the production of aluminum which consists of a support body with an open-pore structure that is continuously fed from aluminum-aluminide stocks.
  • the working surfaces of the cathodes are slightly inclined so that the separated aluminum can easily drain onto the cell bottom.
  • the object of the present invention is to further develop the known electrolysis cells in such a way that the current density in the electrolysis bath can be reduced to values below 0.60 A / cm 2 , but to limit the metal production of the electrolysis cell proportional to the current intensity I and at the same time to reduce the electrical energy consumption by up to decrease by 20%.
  • the cell voltage U z is composed of the ohmic voltage drop of the cell IR z and the polarization voltage U p :
  • U e.g. IR e.g. +
  • U p I electrolysis current
  • the electrolysis cell is operated in a thermal equilibrium, and it has always been the aim of the experts to minimize energy consumption and heat losses for reasons of cost.
  • the reduction in energy consumption shown here leads, for example, to the above-mentioned total consumption of 10 to 11 kWh / Al.
  • Electrolytic cells of older designs were and still are mostly operated from the long sides, i.e. from there, aluminum oxide is fed into the electrolysis bath at periodic intervals of several hours by injecting the covering crust with the aluminum oxide above it.
  • the oxide metering was moved to the central zone of the electrolysis cells, e.g. in the entire Mittelgasse or at favorable points between the two usual rows of anode blocks.
  • Computer-controlled, automatically operated crushing and charging devices are used for the oxide metering, which, according to the specified program, have a relatively low oxide concentration of approx. Maintain 1 - 4% by weight in the electrolyte.
  • feeding of aluminum oxide along the outer edges is provided in the electrolytic cell according to the invention, either with permanently installed or movably arranged crushing swords, with which the lateral covering crusts are broken in more or less large sections, or also selectively with the help of a point meter that can be moved along the entire side front according to the program.
  • the amounts of heat led to the edge by the liquid aluminum and the electrolyte melt are used there to heat and dissolve the oxide which has been injected or metered in.
  • the highly heat-conducting aluminum is kept further away from the side wall by a resistant side base, the height of which is adapted to the aluminum layer on the cathode base.
  • the electrolysis cell according to the invention has fewer leaks by design and the housing only has to be opened once a day for metal suction via a relatively small flap, the exhaust gas volume can be reduced to more than half without any risk of fluorine emission. Cooling of the electrolysis cell by the extracted gas is not required.
  • the carbon anode is burned by the electrolytically separated oxygen to an anode gas, which in addition to CO consists mainly of CO 2 .
  • This anode gas collects close to the anode blocks in the form of many bubbles and migrates in the electrolyte melt to the block edges, where it rises and escapes.
  • the gas bubbles cause the so-called bubble resistance, which means an increased ohmic resistance for the electrolysis current.
  • this bubble resistance is reduced by inclined anode surfaces, lower anodic current densities and an oxide concentration of approx. 4% by weight. 0.1 V (approx.
  • the first question to be clarified is the initial value to which the reduction in specific anode consumption can be based. because it depends on a number of factors.
  • a specific anode consumption of 0.43 kg C / kg Al is considered good, peak consumption of 0.41 kg C / kg Al is achieved under favorable conditions. Due to the design-related reduction in air oxidation of the anode blocks of the method according to the invention, the values for the specific anode consumption fall below 0.40 kg C / kg Al.
  • the dust and fluorine-containing gas extracted from the electrolysis cells is nowadays fed to a dry exhaust gas cleaning system in which the gaseous fluorine in the form of HF is adsorbed on aluminum oxide and the fluorine-containing dust particles are separated out in filter systems.
  • the fluorine emission does not only depend on the efficiency of the exhaust gas cleaning system.
  • the sheet metal housing with which the electrolytic cells are encapsulated must be partially opened for various operations. These opening times result in an additional fluorine emission.
  • the longitudinal gates of the housing have to be opened for crust breaking and oxide charging.
  • the anode rods of all blocks have to be detached from the lower row of nipples and attached to the subsequent upper row in a relatively lengthy process at certain time intervals with the side gates open. The lower row of contact nipples is then pulled. The gas extraction is not effective even if a layer of new anode blocks has to be put on.
  • the electrolytic cell according to the invention takes advantage of the prebaked continuous anode, which is known to be able to achieve higher metal purities than the prebaked discontinuous anode.
  • the higher degree of contamination in the latter process is largely due to the fact that the steel nipples of the anode blocks in the electrolytic cell are subject to greater corrosion and that the anode residues with the thick covering layer of bath material and oxide have to be processed and recycled.
  • the abrasion of iron and rust in the crushing, grinding, transport and silo equipment of the processing and recycling systems causes, for example, a significantly increased iron content in the aluminum produced.
  • the method according to the invention dispenses with steel nipples which are susceptible to corrosion and are embedded in the anode block and permits contemporary cell current strengths of over 150 kA.
  • An essential component of the electrolytic cell according to the invention is an anode system with pre-burned continuous anode blocks, preferably for electrolytic cells with a total current of over 150 kA. Uniform short current paths between their current connections and the electrolysis bath are provided for the individual anode blocks of this system. This results in an equally high voltage drop and an equally large current density for all anode blocks.
  • the homogeneous current density distribution of the anode system according to the invention means an enormous advantage with respect to a calm, steady electrolysis process, a high current yield and a low specific energy consumption compared to those with pre-burned discontinuous anode blocks.
  • all the anode blocks are in a different state of consumption, which inevitably leads to a very large unevenness in the individual voltage drops and current intensities in the individual blocks. Consequently, there are always two groups of anode blocks in the discontinuous anode system, one of which is below the nominal current in terms of its current consumption or current density and the other.
  • the current in the block rises from zero when changing to a maximum when removing the rest. To make matters worse, it takes a day or two to replace a new anode block before the block has reached the average operating temperature and fully participates in the electrolysis process. With the trend towards larger electrolysis and anode block units, the disadvantages just mentioned grow.
  • anode block daily in the anode system with pre-burned discontinuous anode blocks to replace, ie to take out the rest of an ancillary block (approx. 20 - 30% of the initial weight) and to replace it with a new one.
  • an ancillary block approximately 20 - 30% of the initial weight
  • This anode block change significantly interferes with the electrolysis process and leads to the aforementioned unevenness in the anodic current density distribution.
  • the addition of anode blocks by the method according to the invention does not influence the actual electrolysis process at all; Because only about once a month is it necessary to place a new layer of anode blocks on the anode block stacks in the electrolysis cell.
  • the anode blocks are all arranged in two longitudinal rows.
  • the anode blocks extend over the entire width of the cross-sectional area planned for the anode within the electrolysis trough.
  • the removal of the top layer of solidified electrolyte melt and aluminum oxide from the residual anodes and their subsequent cleaning is saved.
  • the bath material to be cleared, shredded and recycled into the electrolytic cells accounts for approximately 20% of the anode block operating weights.
  • the residual weight is also of the anodes leaving the electrolytic cell, depending on the mode of operation, 20-30% of their initial weights. It is easy to see that this internal recycling of the anode residues leads to a permanent additional load on the anode factory in the three main process stages preparation, shaping and burning of 20-30% compared to a basic capacity of the method according to the invention.
  • a further disadvantage is that the anode residues contain fluorine and, therefore, in order to meet the emission requirements, an exhaust gas cleaning system for the fluorine-laden furnace exhaust gases has to be installed downstream of the anode block ring furnace.
  • the so-called anode stripping takes on the task of taking over the remaining anodes from the electrolysis, allowing them to cool in a warehouse, cleaning them, separating the anode residues and cast sleeves from the anode rods and preparing them for reuse.
  • the new anode blocks are connected to the anode rods via cast-in or stamped-in steel nipples and thus made ready for use in electrolysis.
  • nipple holes have to be drilled in the anode blocks in a preparation station and the steel current contact bolts have to be firmly inserted with a suitable carbon mass.
  • these preparatory work or similar measures are not required because the power supply is accomplished by a nipple-free type of contacting, which will be described in more detail.
  • the anode blocks used continuously in the preparation station receive on their underside a connecting layer made of an adhesive or putty, which is normally produced on the basis of petroleum coke and electrode pitch.
  • the putty is poured in the hot, flowable state onto the preheated anode block connection surface, i.e. applied to the underside of the anode block facing upwards, approx. 2 cm thick.
  • the station for applying the putty is avoided. This eliminates installation space and heating energy for preheating the anode blocks and melting the putty.
  • the construction and mode of operation of the electrolysis cell according to the invention make it possible to apply the putty as granules to the warm upper sides of the anode blocks located in the electrolysis cell, in order to then immediately apply cold, preheated or even best the anode blocks, which are still warm from the firing process. If necessary, the latter only have to be freed from the packing material of the kiln, but otherwise do not require any special preparation. It can be seen that thermal energy, investment costs and labor are saved at this point in the process according to the invention.
  • the anode system according to the invention with pre-burned continuous anode blocks enables the electrolytically active undersides of the anode blocks, which are immersed in the electrolyte melt, not only to be flat - as is generally customary - in the horizontal direction, but also to be wedge-shaped or curved. If there is no aluminum bath with a flat surface as an effective cathode, the fits Anode block in the melt flow electrolyte in its interface shape to the shape of the opposite cathode surface.
  • the electrolysis cell has a roof or semi-barrel shape in the form of a base constructed from carbon cathode blocks in accordance with the number of anode blocks.
  • the cathode blocks have, for example, the shape of a triangle, semicircle or similar geometrical structure.
  • a flat cavity or collecting space for the liquid aluminum is set up below the parallel and parallel running cathode blocks in the electrolysis cell.
  • an alley is provided between the lower edges of the parallel arranged cathode blocks as a connection between the flat floor space for the liquid aluminum and the space above for the electrolyte melt.
  • the aluminum is deposited by the electrolysis current on the inclined surfaces of the cathode blocks and flows into the flat floor space below the cathode blocks.
  • the great magnetic field problem of conventional, high-current electrolysis cells is that the current-carrying layer of liquid aluminum on the cathodically connected carbon base interacts with the magnetic fields, by which all current conductors are surrounded inside and outside the electrolysis cell.
  • the magnetic field forces exerted on the liquid aluminum layer displace the aluminum and cause a metal bulge and rotation.
  • the magnetic field effect is eliminated in that the electrolysis current entering the cathode does not have to pass through an aluminum bath, because the collecting basin for the liquid aluminum is located outside the current passage, namely below the cathode blocks.
  • a notable amount of aluminum conductive metal is invested in the busbars outside the electrolysis cells, e.g. in the order of 50 t per 1000 t annual capacity.
  • the shortest and most rational paths can be chosen for the current connections between the series-connected electrolytic cells and for the current distributions carried on anode and cathode bars will.
  • the risers which are arranged in the middle of the electrolysis cells, for example for reasons of magnetic field compensation and which generally hinder the operation of the electrolysis cells, can be moved to the end of the cell in the electrolysis cell according to the invention, where they do not interfere.
  • the free, magnetic field-independent choice of busbar arrangement saves installed lead aluminum by up to approx. 20%. In addition, somewhat lower power loss in the power supply line can be expected.
  • the steel bars for the power supply are embedded in the carbon base serving as the cathode on the underside of the carbon groove in the grooves of the carbon cathode blocks. It it often happens that the carbon base, especially with increasing cell age, has cracks through which the thin aluminum above it penetrates to the steel cathode bars and dissolves or dissolves them through the formation of alloys.
  • One of the most common causes for switching off and decommissioning the electrolytic cells is therefore the dissolution of iron from the cathode bars in the aluminum bath.
  • this cause of failure is avoided by the fact that on the one hand the aluminum bath is located below the cathode blocks (see point C 1) and on the other hand the steel bars are embedded in the cathode blocks from above.
  • the bottom of the electrolytic cell carrying the aluminum layer is not subjected to current.
  • it is far less exposed to chemical and mechanical wear and the destructive sodium infiltration, which experience has shown to be accompanied by volume expansion and conversion processes, than the known double-function cathode bottom.
  • the separate construction of the cathode and cell bottom according to the invention also results in an increase in the durability or lifespan of the electrolytic cell lining. This not only means a cost reduction, but also eases the serious disposal problem of the used cell lining materials.
  • sodium-resistant graphite cathode blocks with a high thermal conductivity of 80-100 W / mK are used in the electrolysis cell according to the invention, less heat is dissipated into the floor insulation.
  • the cathode blocks are subject to less abrasion because they lack the metal flow and possibly the grinding effect of aluminum oxide sludge.
  • the voltage drop in the cathode blocks and their leads is also significantly lower.
  • the anode system described in the literature cited above is not usable for the main objectives of extremely low energy consumption, extremely low environmental impact, a high degree of automation and humanization or elimination of physically and health-damaging operations.
  • the reasons lie primarily in the fact that the prebaked anode blocks of the known continuous anode system have contact nipples with detachable anode rods inserted laterally. Moving and re-attaching the anode rods and pulling the contact nipples takes a lot of manual work.
  • the side space of the electrolytic cell is for these manipulations occupied and cannot be used for other devices, e.g. automatic oxide feed devices.
  • the side gates of the electrolytic cell must be opened for the operations.
  • the introduction of current into the anode blocks leads to long current paths in the anode blocks via the contact nipples arranged at the front and in relatively high steps.
  • the long current paths result in an increased voltage drop in the anode, which is on average almost 0.5 V higher than in discontinuously used anode blocks.
  • the anode blocks would have to be even about a third longer than previously used, so that the voltage difference in the anode blocks between current entry and exit would deteriorate significantly.
  • the putty is applied in the form of granules on site in the electrolytic cell in order to be able to place anode blocks at approx. 200-250 ° C.
  • the coking conditions of the kit layer are also significantly improved in order to achieve a higher density and strength.
  • EP-A 0 380 300 an electrolytic cell with a continuous anode was proposed. This Proposal differs fundamentally from the electrolytic cell according to the invention in that the current supply to the anode blocks takes place directly via flat, rigid clamping devices with horizontal pressure and not via compressed, binder-free graphite or coke grain packs.
  • the proposal according to EP-A 0 380 300 has significantly different features with regard to the arrangement, mounting and repositioning of the anode block stacks.
  • FIGS. 2-8 The essential features of the electrolytic cell according to the invention are shown schematically in FIGS. 2-8.
  • the simplified representations are to be regarded as exemplary embodiments.
  • FIG. 1 shows a section of the central part from the electrolytic cell shown in longitudinal section, with the still conventional flat cathode and anode (comparative example).
  • FIG. 2 shows a partial area similar to that in FIG. 1, but with a novel surface-enlarging design of the cathode.
  • Fig. 3 is similar to the drawing section of FIGS. 1 and 2, but with angular relationships of 60 ° in the juxtaposition of anode and cathode.
  • FIG. 4 relates to the anodic part of the electrolytic cell and is a section along the line AB in FIG. 3.
  • Fig. 5 is a section along the line CD in Fig. 3, and only up to the axis of symmetry of the cell. 5 shows the side part of the electrolysis cell in particular.
  • Fig. 6 is a plan view of the electrolytic cell, but without the front furnace heads with the supporting structures and lifting devices.
  • FIG. 7 is an enlarged partial area from the top view in FIG. 7.
  • FIG. 8 the electrolytic cell according to FIG. 3 and section EF is outlined with omission of various details in the overall cross section.
  • the anode blocks 1 and 2 extend in a continuous length transversely to the axis of the electrolytic cell and are connected to one another by the kit layer 3.
  • a cross connector 10 made of flat steel with a footbridge 11 is arranged in the alley 4 between two adjacent anode block packages.
  • the gap between the cross connector 10 and the long side of the anode block is filled with a coarse graphite grain 13, which is pressed together by the steel pressing bar 12.
  • the power supply device thus consists of the construction elements 10, 11 and 12 and the compressed graphite grain 13.
  • grain fractions from petroleum coke, pitch coke or broken anode block residues can also be used; but these carbon materials give a 3 to 6 times higher electrical resistivity.
  • a granular mixture of electrographite and coke can also be used.
  • the harder coke grains increase the friction between the grain packing and the anode block and may therefore be necessary to prevent the anode block packages from slipping.
  • the alley 4 closes the alley 4 over its entire length, so that no electrolyte vapors and anode gases can escape through the alley 4 from bottom to top.
  • the lower, hotter side surfaces of the anode blocks are protected against air admission and combustion from above.
  • the specific pressing pressure on the graphite grain is in the order of 150-300 N / cm 2 .
  • the footbridge 11 the elevated temperatures and underside exposed to increased corrosion, a heat and corrosion resistant steel or other metal alloy is used; especially for reasons of short current paths and low voltage drops or low power losses, the position of the power supply device is to be brought as close as possible to the bath crust 6.
  • the cross connector 10 has a slight, trapezoidal extension toward the foot web 11. In this way, the lateral pressure of the granule pack 13 on the anode block is increased while the vertical pressing force on the granule remains the same.
  • the anode block package designated with the reference numbers 1 and 2 is immersed in the electrolysis bath or in the electrolyte melt 5, the immersing, electrolytically active part of the anode package taking on a surface shape similar to that of the opposite cathode.
  • the anode block package forms a horizontal, flat anode surface.
  • FIGS. 2 and 3 show exemplary embodiments with an enlarged active area of the anode blocks and lower current density in the melt flow electrolyte 5.
  • anode cross-sectional profiles with a tip of 90 ° and a corresponding angle of repose of 45 ° are provided within the electrolysis bath.
  • these angles are 60 °.
  • FIG. 1 For the exemplary embodiment in FIG.
  • the cathode blocks 14 and 18 in FIGS. 3 and 2 have triangular cross sections with the angles indicated in the drawings.
  • a rectangular longitudinal groove 16 is formed or worked into the cathode block 14 with the profile cross section of an equilateral triangle from above, into which a steel bar 15, also known in specialist circles as cathode iron, is embedded for the current discharge.
  • the cathode iron 15 is embedded in the groove either by pouring cast iron or by stamping in an electrically highly conductive carbon mass.
  • the groove space above the cathode iron 15 is filled with a tamping mass on a carbon or graphite basis that solidifies through coking of the binder.
  • the cathode blocks 14, 18 and 20 per se consist of the commercially available electrode raw materials for this product, but it is preferred to add refractory carbides, nitrides or borides to the carbon materials. 3 and 2 that the cathode blocks 14 and 18 are surrounded all around with electrolyte melt.
  • the resistance heat generated in the cathode block 14, in the cathode iron 15 and in the transitions remains exclusively in the electrolysis room.
  • the voltage drops between the active inclined cathode surfaces and the current-dissipating cathode iron are lower than in conventional cathode constructions because of favorable current distribution and short current paths, so that in total approx. 0.5 kWh / kg Al can be saved.
  • the aluminum deposited on the inclined cathode surfaces flows into the aluminum bath 7 located below the cathode blocks.
  • the latter is not affected by the current flow, so that no electrodynamic forces can be caused by interaction with the strong magnetic fields.
  • the dissolving effect of the aluminum in the collecting basin under the cathodes cannot reach the cathode iron 15 or 19.
  • the carbon-containing lining designated 8 in FIGS. 2 and 3 has the task of preventing the thermal insulation 9 from penetrating to protect aluminum and components of the electrolyte melt 5. Since no electrical conductivity is required from the lining layer 8, it is advantageously possible to use dense composites of carbon, oxides and carbides, which ensure greater tightness and thermal insulation.
  • the refractory lining with layers 8 and 9 offers better, more constant heat protection and a longer service life than that according to the well-known combination of current-carrying carbon floor and thermal insulation installed underneath.
  • FIG. 4 shows a section (see section line AB in FIG. 3) through the press bar 12 and the graphite grain packing 13.
  • the press bar 12 has the vertical struts 22 on both sides, at the upper ends of which tabs 23 with holes projecting beyond the anode bars 33 are attached are.
  • the structural part made of press bolt 12, vertical strut 22 and tab 23 is referred to in the further description as a clamp 24.
  • the pressure and tension on the clamping bracket 24 is exerted by a spindle bracket 25 which is mounted on the anode bar 33.
  • the spindle bracket 25 contains the spindle 26, which can be actuated or rotated by the square 27.
  • the cylindrical nut 29 with the perforated bracket 30 is seated on the spindle 26.
  • the sliding bush 28 serves for the precise guidance of the cylindrical nut 29 and has a longitudinal slot in which the perforated bracket 30 moves up and down when the spindle 26 rotates.
  • the tab 23 of the clamping bracket 24 and the tab 30 of the cylinder nut 29 are connected by the bolt 31 (see also Fig. 7).
  • the clamping bracket 24 or the graphite grain pack 13 is put under pressure. After relieving pressure and pulling the connecting bolts 31, each clamping bracket 24 can be removed individually.
  • Each anode block packet can also be used at any time during cell operation, e.g. in the event of malfunctions, after releasing the tensioning bracket 24.
  • the side boundary consists of the anode bar 33, in the lower area, the anode frame 34, which is composed of the frame wall 35 and the bracket 36.
  • Anode bar 33 and bracket 36 are screwed together with good electrical conductivity.
  • the gusset plates 37 are welded therein at intervals.
  • the cross connectors 10 are attached to the inside of the frame wall 35. A detachable connection by means of plug-in screws is also preferred for this.
  • the electrolysis current takes its way from the anode bar 33 made of aluminum via the thick-walled anode frame 34 made of steel to the cross connectors 10, and from there via the graphite grain packs 13 into the anode block packs.
  • a smaller partial stream can flow directly from the anode bar 33 to the cross connector 10 via the guide bar 32, which is welded to the cross connector 10 at the lower end and screwed to the anode bar in the upper part (see FIGS. 7 and 8).
  • the tensioning bracket 24 can also transmit current from the anode bar 33 to the graphite grain packing 13.
  • the side part of the electrolytic cell shown as a sectional view in FIG. 5 shows the charging device for aluminum oxide in a sketchy simplification.
  • the crushing and dosing device outlined in FIG. 5 is intended primarily to illustrate the principle according to the invention.
  • the crushing plunger 43 which breaks through the covering crust 6 and makes a hole for the alumina feed, receives its thrust from a pneumatic cylinder 44 which is attached to the stationary steel box 38.
  • the steel box 38 spans the entire length of the electrolysis cell, rests on two support structures at the ends and serves as a storage and loading container for the aluminum oxide 40 Chambers (not shown) can also house the steel box 38, such as aluminum fluoride.
  • the discharge flap 41 for the aluminum oxide is installed at the lower end of the steel box 38. When the tilting shaft 42 is actuated, the aluminum oxide runs out of the discharge flap 41, at the same time preventing the supply of aluminum oxide from the steel box 38.
  • the frequency and amount of oxide metering is carried out in a remotely controlled, automatic manner
  • mobile crushing cylinders with a chisel can also be provided, which can be moved along the entire side front and can carry out the crushing process in any computer-controlled position.
  • Another variant of operating the entire side front and feeding it with aluminum oxide consists of a continuous breaking sword with breaking mandrels.
  • the steel box 38 is filled with aluminum oxide 40 via the pipe socket 39, which can also be part of an oxide distribution system.
  • the side space of the electrolysis cell is clad to the outside by the hinged aluminum sheet gates 45.
  • the electrolysis cell is shielded from the outside by similar aluminum sheet panels 47 (see FIG. 6).
  • the entire anode space is covered by the horizontal gates 46.
  • the lower right field of FIG. 5 illustrates a section of the tub delivery of the electrolytic cell.
  • the steel wall 50 of the electrolysis bath is protected by a cryolite and aluminum-resistant edge plate 51.
  • a thick crust 52 of solidified electrolyte melt rich in aluminum oxide has formed in front of the edge plate 51 as effective front protection against the electrolysis bath 5.
  • FIG. 6 The plan view of the electrolytic cell in FIG. 6 explains how the anode exhaust gas is sucked out of the electrolytic cell.
  • At the ends of the electrolytic cell there are two U-shaped downward connections in tight connection to the anode blocks open hollow boxes closed at the top by the cover plate 28.
  • a duct connection 49 leads from the cover plate 48 to the exhaust pipe. 5 and 6 can be seen that the superstructure of the electrolytic cell are considered to be tightly encapsulated and no dust and exhaust gas can escape into the environment under normal operating conditions.
  • FIG. 7 again shows how the upper structure of the electrolytic cell, ie the arrangement and current supply of the anodes, is used to seal the surface of the electrolytic bath covered with anode upwards.
  • the horizontally movable sheet gates 46 can be provided for further safety of the exhaust gas detection above the anode field.
  • the support structure supporting the anode superstructure at the ends of the electrolytic cell is not shown.
  • the cathode block 14 with the steel bar 15 embedded therein rests on the central and lateral bases 53 and 54 made of carbon or graphite.
  • the bottom corner crust 55 forms in front of the side bases 54.
  • the edge joint between cathode block 14 and edge plate 51 is stamped out with a carbon-containing mass 56.
  • the interpolar distance between the anode and the cathode is set or regulated in a manner known per se after the cell voltage has been specified by actuating the lifting spindles on which the box-shaped unit comprising the anode bar 33 and the anode frame 34 is suspended.
  • the unit consisting of anode bar and anode frame must be raised in relation to the anode block packages in certain periods.
  • the anode frame moves down and back up within 10 - 20 cm.
  • an auxiliary bridge is used, on which the anode block packages are temporarily suspended.
  • the auxiliary bridge has vertically arranged holding arms, which during or after after the auxiliary bridge has been placed in the rectangular vertical grooves 60 (see FIGS. 6 and 7) of the anode blocks 1 to approximately 20 cm above the electrolysis bath.
  • the holding arm is composed of a fixed U-profile, the lower end of which is chamfered in a wedge shape, and a rectangular rod that can be moved therein and has a wedge shoe at its lower end, which nestles against the chamfered legs of the U-profile.
  • the holding arm is clamped at the lower end in the anode groove 60 by hydraulically pulling up the rectangular rod.
  • a back serration both on the wedge shoe on the rectangular bar and on the lower end of the U-profile ensures a non-slip fit of the holding arm in the anode groove 60.
  • all clamping brackets 24, from which the graphite grain is pressed are loosened by means of the spindle blocks 25, and the contact between the anode bar and the anode frame is raised a little under a sliding current contact.
  • the clamps 24 are tightened again, the holding lances of the auxiliary bridge are released and the auxiliary bridge is removed and removed from an overhead crane.
  • Another option for moving the contact devices and the overall frame upwards relative to the anode packages is to push the anode packages down with the aid of hydraulic cylinders and at the same time to move the anode beams with frames up the same distance.
  • the electrolytic cell according to the invention contains various individual innovations which only achieve maximum progress in their meaningful integration.

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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)
EP92109006A 1991-06-04 1992-05-29 Elektrolysezelle zur Aluminiumgewinnung Expired - Lifetime EP0517100B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4118304A DE4118304A1 (de) 1991-06-04 1991-06-04 Elektrolysezelle zur aluminiumgewinnung
DE4118304 1991-06-04

Publications (3)

Publication Number Publication Date
EP0517100A2 EP0517100A2 (de) 1992-12-09
EP0517100A3 EP0517100A3 (en) 1993-03-24
EP0517100B1 true EP0517100B1 (de) 1997-05-14

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ID=6433157

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EP92109006A Expired - Lifetime EP0517100B1 (de) 1991-06-04 1992-05-29 Elektrolysezelle zur Aluminiumgewinnung

Country Status (7)

Country Link
US (1) US5286353A (no)
EP (1) EP0517100B1 (no)
AU (1) AU653404B2 (no)
CA (1) CA2070372A1 (no)
DE (2) DE4118304A1 (no)
NO (1) NO920488L (no)
RU (1) RU2041975C1 (no)

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US5888360A (en) 1994-09-08 1999-03-30 Moltech Invent S.A. Cell for aluminium electrowinning

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GB2372257A (en) * 1999-06-25 2002-08-21 Bambour Olubukola Omoyiola Extraction of aluminum and titanium
EP1581672B1 (en) * 2002-12-12 2017-05-31 Metalysis Limited Electrochemical reduction of metal oxides
CN1323192C (zh) * 2004-12-03 2007-06-27 河南省鑫科工程设计研究有限公司 预焙阳极粘接法电解铝生产工艺
CN101985762A (zh) * 2010-10-20 2011-03-16 云南铝业股份有限公司 一种连续阳极立式v型双斜面铝电解槽
DE102011078002A1 (de) * 2011-06-22 2012-12-27 Sgl Carbon Se Ringförmige Elektrolysezelle und ringförmige Kathode mit Magnetfeldkompensation
DE102011086044A1 (de) * 2011-11-09 2013-05-16 Sgl Carbon Se Kathodenblock mit gewölbter und/oder gerundeter Oberfläche
FR3016896B1 (fr) * 2014-01-27 2016-01-15 Rio Tinto Alcan Int Ltd Caisson de cuve d'electrolyse.
FR3016890B1 (fr) * 2014-01-27 2016-01-15 Rio Tinto Alcan Int Ltd Systeme de capotage pour cuve d'electrolyse
FR3016891B1 (fr) * 2014-01-27 2017-08-04 Rio Tinto Alcan Int Ltd Dispositif de stockage d'une charge au-dessus d'une cuve d'electrolyse.
FR3016898B1 (fr) * 2014-01-27 2017-08-04 Rio Tinto Alcan Int Ltd Dispositif de percage d'une croute de bain cryolithaire apte a etre positionne en peripherie d'une cuve d'electrolyse.
FR3016895B1 (fr) * 2014-01-27 2017-09-08 Rio Tinto Alcan Int Ltd Dispositif de levage d'ensembles anodiques d'une cuve d'electrolyse.
FR3016892B1 (fr) * 2014-01-27 2016-01-15 Rio Tinto Alcan Int Ltd Dispositif de prechauffage d'un ensemble anodique.
FR3032454B1 (fr) * 2015-02-09 2020-10-23 Rio Tinto Alcan Int Ltd Systeme d'etancheite pour une cuve d'electrolyse
CN106894055B (zh) * 2016-12-30 2018-07-17 山西精之铝科技有限公司 内置导体的连续铝框阳极铝电解槽
CN110552023A (zh) * 2018-05-30 2019-12-10 沈阳铝镁设计研究院有限公司 阳极组运输及热残极冷却污染物收集的运输车及使用方法
CN109280939B (zh) * 2018-12-17 2020-09-25 党星培 一种控制电解槽槽电压和夹持框位置的方法
CN112126948A (zh) * 2020-09-24 2020-12-25 河南中孚铝业有限公司 铝电解槽侧部炉帮修复系统
CN114457386B (zh) * 2022-01-11 2024-04-16 雷远清 一种含惰性阳极处理的电解铝方法

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US5888360A (en) 1994-09-08 1999-03-30 Moltech Invent S.A. Cell for aluminium electrowinning

Also Published As

Publication number Publication date
EP0517100A2 (de) 1992-12-09
DE4118304A1 (de) 1992-12-24
NO920488L (no) 1992-12-07
DE59208475D1 (de) 1997-06-19
AU1729292A (en) 1992-12-10
RU2041975C1 (ru) 1995-08-20
EP0517100A3 (en) 1993-03-24
AU653404B2 (en) 1994-09-29
CA2070372A1 (en) 1992-12-05
NO920488D0 (no) 1992-02-06
US5286353A (en) 1994-02-15

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