US3029194A - Furnace and process for the electrolysis of aluminum - Google Patents

Furnace and process for the electrolysis of aluminum Download PDF

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US3029194A
US3029194A US480509A US48050955A US3029194A US 3029194 A US3029194 A US 3029194A US 480509 A US480509 A US 480509A US 48050955 A US48050955 A US 48050955A US 3029194 A US3029194 A US 3029194A
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furnace
bath
electrolysis
aluminum
anode
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Varda Giuseppe 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
    • 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

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  • PEG. 1 is a prospective view, partly in section along the line A-A of FIG. 4, showing a multiple furnace emplo *ing a series of bipolar inclined electrodes for the electrolysis of aluminum;
  • FIG. 2 is a vertical cross-sectional view of an elemental furnace, according to the invention, for the electrolysis of aluminum;
  • FIG. 3 is a vertical cross-section of a multiple furnace according to the invention.
  • FIG. 4 is a plan view of the multiple furnace shown in FIG. 3;
  • FIG. 5 is an oblique view of a portion of an anode structure illustrating one way in which the anodic surface may be integrated or renewed;
  • FIG. 6 is a view similar to that of FIG. 5 showing an alternative way for renewing the anode.
  • Alumina A1 0 breaks up into metallic aluminum and oxygen which combines with the anodic carbon.
  • the anodes dip partially into the bath of molten cryolite and receive the current from above through metallic conductors, whence the current passes over to iron stubs or nipples which intimately contact the anodic carbon.
  • the current passes from the foot of the anode (i.e.
  • the cathode being formed by the furnace bottom consisting of a carbon sole with a layer of liquid aluminum on top.
  • the current leaves the carbon bottom through iron cathodes which are in intimate contact with the cathodic carbon.
  • the whole is thermically insulated on the outside with layers of refractories and insulating material held in place by a strong external me al shell.
  • the refractory lining should never come into contact with the bath, being separated from the latter as long as the furnace is new at least, by means of carbon sides.
  • anodic carbon will be consumed, but the level of liquid aluminum increases during electrolysis. The level of aluminum goes down immediately upon tapping.
  • the electrode spacing is kept approximately constant and may vary in commercial aluminum furnaces from 3.5 to 9 cm., in different installations.
  • the electrode spacing is oneof the peculiarities of the conventional furnace, and its adjustment, at first sight, seems simple enough.
  • the alumina content in the bath drops below a certain value, the so-called anodic effect will take place and the furnace voltage will increase suddenly from 5 v. up to between 30 and 60 v.
  • the crust (not shown) formed by freezing on top of the bath has to be broken up by mechanical means so that a new charge of alumina may be fed into the bath to restore normal operating conditions.
  • the new charge of alumina is always put upon the crust in advance, both to preheat it and to better insulate the bath.
  • the gases evolving from the bath surface (usually CO +CO) are removed, in a closed furnace, by means of a big exhaust system (not shown) that will also remove the volatile hydrocarbons caused by cokification of the fresh carbon paste fed from the top to the self'baking Soderberg anodes. lf pro-baked anodes are used, the consumed anodic parts are taken out of the bath and replaced periodically by entirely new anodes.
  • High unit consumption of power is one of the main drawbacks of present day furnaces. Overall power consumptions of less than 18 kwh. on direct current, and about 20 kwh. on alternating current, are hard to obtain even if optimum values of about 16 kwh. per kilogram aluminum can be attained for short lengths of time.
  • Another object of my invention is to provide a new type of furnace having a very low unit consumption of power as well as of other items affecting the cost of the aluminum produced.
  • the present invention contemplates the provision of a new elemental furnace having an electrically consumable but stationary anode as well as a multiple furnace derived therefrom.
  • the elemental furnace for electrolytic production of Al from A1 0 is characterized by its electrolytic cell having an inclined interspace between plane parallel faces of two stationary carbon block electrodes arranged side by side, one anodic and the other cathodic, into which there penetrate the metal conductors (nipples) carrying the current.
  • the metal conductors or nipples may terminate respectively at equal distances from their electrode faces; and the lateral walls of the interspace, as well as all the other internalsurfaces of the furnace, are lined with a non-conductive protective layer.
  • Below the interspace there is provided a chamber for collecting the liquid aluminum formed by.
  • the electrolytic process which chamber is provided with a tap hole.
  • a chamber is provided above the interspace for the gases developed between the carbon electrodes during the electrolysis.
  • the anodic electrode has an active layer built up from the bath side.
  • stationary electrodes or blocks are meant at least two electrodes or blocks every two points of which have a permanent distance relationship between each other while the spacing relationship between the electrodes or blocks may vary (e.g. because of increases of the electrode spacing on account of the anodic consumption).
  • carbon is used herein to designate any carbonaceous electrode materials such as conventional prebaked carbon anodes of amorphous carbon agglomerates, as Well as graphite, or compositions containing a prevailing proportion of the chemical element C or of said carbonaceous materials,
  • the multiple furnace is characterized by a plurality of analogous cells with lower metal (collecting) chambers and with upper gas chambers like those of said elemental 4 furnace, the interspaces constituting said cells being formed by stationary carbon blocks, without metallic conductors, having cathodic and opposed built-up anodic faces, and aligned between two stationary blocks of nippled carbon arranged at the ends of the multiple furnace and acting as first anode and as last cathode respectively, for the two terminal cells.
  • the basic elements of the furnace for the electrolysis of aluminum consist of the three following parts: a practically horizontal upper chamber 12 for gases; an inclined gap 13 below, which communicates with the upper chamber 12 and constitutes the electrolytic cell proper and has inclined conducting main walls; and a lower chamber 14 for the molten metal, which is located beneath the electrolytic cell proper and communicates with the cell, being preferably wider and shallower than the latter.
  • the cell is essentially made up of two electrodic carbons, one of which may be of graphite 15 and the other 16 of amorphous carbon agglomerates such as are manufactured by known methods for electrodic purposes.
  • Both electrodes are planar on all sides.
  • Both conducting faces slope downwards, and are parallel, of substantially the same area and face each other.
  • the angle of inclination of electrode faces is between 15 and 45 degrees with respect to the vertical.
  • the faces are usually less than 12 cm. apart, the gap between them being preferably from 4 to 8 cm. wide.
  • the upper bath surface is equal to or greater than the area of the horizontal cross-section of the gap.
  • the ratio between the measure of the gaps horizontal cross-section and the corresponding cell volume of the electrodic gap is less than 0.10 cm.- and preferably less than 0.03 CHI-T1.
  • the current arrives at or starts from either carbon electrode through metallic stubs or nipples 17 of iron for example.
  • the stubs are in intimate and extensive contact with the carbons.
  • the ends of all stubs of each electrode are equally distant from the sloping surface which acts as anode (carbon 16) or, respectively, as cathode (carbon 15), the distance from said sloping surfaces being less than 50 cm. and preferably less than 20 cm.
  • the number and size of the stubs 17 are such as to allow a most uniform current distribution and flux lines as parallel as possible across both electrodic surfaces.
  • the cell side-walls are made of one or more sufficiently bath resistant, electrical and thermal insulating materials.
  • the inner layer 18 in contact with the moltencryolitic bath is preferably made of a solid materialwhich has previously been fused or sintered at extremely high temperature (in order also that its porosity be reduced); it must resist the bath components and be a non-conductor of the current or at least a poor one. Linings of aluminum nitride, aluminum oxide, magnesia and other known inert materials the latter preferably fused or sintered, are suitable for those purposes.
  • the walls, bottom and covering of the lower chamber for the metal are entirely lined with said inert material.
  • the lining is supported by a refractory layer 19 preferably of calcined magnesite.
  • the lower chamber 14 is appreciably wider and, as a rule, shallower than the cell between both carbon electrodes.
  • the volumetric content of the lower chamber should preferably be about equal to or somewhat greater than the maximum capacity of the cell above.
  • the cross-section of the lower chamber is trapezoidally-shapcd, but rectangular, rhombic shapes etc., or sections similar to these, may as well be adopted.
  • furnace sidewalls are preferably higher than the carbon electrodes, an upper chamber on top of the electrolytic gap is formed, into which gases that develop during electrolysis will evolve.
  • the upper chamber 12 may be closed by means of an easily removable cover (not shown in FIGURE 2). This part of the furnace, in fact, has to be readily accessible for inspection, control and operation.
  • the cover provided there is one, will insulate the upper chamber from the outside and allow for disposal, by known methods, of electrolytic gases in a more practical manner.
  • the sidewalls of the upper chamber are provided with gas ducts (not shown in FIG. 2).
  • Both upper and lower level surfaces etc. of the carbon electrodes are covered with the usual layer 18 of refractory and inert material such as previously described.
  • Alumina may be spread over the top layer both to reduce heat dispersion and to pre-heat the charge which has to be added to the bath at regular intervals.
  • the lower chamber of the metal can be reached either from above, through the upper chamber and electrolytic cell, or from below, through one or two sub-horizontal tapping channels 22 whose orifices are placed under the head of molten aluminum 23 and the overlying cryolitic bath 24.
  • the volumetric capacity (for aluminum) of the lower chamber 14 is 0.8 to 1.5 times the maximum capacity of the cell gap.
  • the second carbon acts as the cathode; upon its inclined face aluminum produced will settle downwards in the form of little drops and/ or a veil conveyed by gravity into the lower chamber 14 whose walls have little or preferably no conductivity.
  • the metal layer 23 which collects into the lower chamber 14 can be in electrical contact, or nearly so, with the cathodic surface of the cell by virtue of the stream of molten aluminum flowing from said surface without leading to trouble.
  • the molten bath may be partly covered by a thin crust of frozen hath (not shown in the figures).
  • the alumina layer on top of the bath and/ or of the electrodes for isolation or preheating, is not shown either.
  • lf direct current kept at constant value of 0.4 amp./ sq. cm., or gradually decreasing from 0.5 to 0.3 amp./ sq. cm., is sent through a furnace of this kind, whose electrodic faces are, for instance, initially about 4 cm. apart, a volage drop of 2.8 to 3.6 v. between anodic and cathodic bars will occur, and a power consumption amounting to from 11 to 15 kwh. per kg. of aluminum produced will result.
  • both chamber and cell above are full of a new molten bath having, preferably, an alumina content of from 6% to 13%.
  • alumina content preferably, 6% to 13%.
  • the molten metal which collects on the bottom of the lower chamber will displace an equal volume of bath.
  • a certain percentage eg. 3% to 5% or less
  • the distance between electrodes is no longer 4 cm. but about 8 cm.
  • the bath level in the cell will be but slightly changed while the lower chamber will be about /1 full of metal.
  • the metal will be tapped as usual or through the spilling channel, whose orifice is kept sealed during operation by means of a refractory plug; or it may be lifted successively from above, until preferably only a thin layer of liquid aluminum is left upon the bottom of the lower chamber.
  • the molten aluminum can also be removed by a suction pipe lowered down through the cell to the bottom of the lower chamber. The metal thus obtained will be subjected to known further treatments.
  • the bath level in the case of the example, will go down to about one half the cell depth. It is however advisable to expose the whole anodic surface by emptying the cellbut not the lower chamber of the molten bath.
  • the molten bath which, in a cell about cm. wide and having a cell depth of 60 cm., amounts to some 20 to 22 liters, is preferably poured into a suitable well-insulated container, to be put back. into the cell as soon as the anode has been integrated as explained below.
  • wellknown devices such as heating ovens, etc., are resorted to.
  • a regular plate 40 of electrodic carbon (see FIG. 5) less than 12 cm. thick, and in this case, about 4 cm. thick, and as wide as the anodic face to be covered, is applied against the consumed anode surface.
  • Such a plate rectangular for instance, and measuring 80 by 70 cm., is slipped into the gap between the electrodes forming the cell and made to adhere to the anode in such a way that the current will not meet, during cell operation, an excessive resistance in passing through the separating layer between old and new anode.
  • Sodcrberg paste 4.1 or graphitic dust and suitable cokifiable carbonaceous binding agent, is to be spread beforehand over the surface of the plate to be contacted.
  • the strips need not be disposed in the direction shown in FIG. 6. If, for instance, the anodic face is 80 by 70 cm., one may employ five strips about 16 cm. by 70- cm. which will of course cover the face entirely. The single pieces are then pasted against the anodic surface alongside one another until the old anode has been entirely covered by the new one.
  • FIGS. and 6 are shown separately, it is to be understood that the above-described integrating procedure is carried out without removal of the electrodes from the furnace.
  • a most evident feature of my invention is that in this type of cell every mechanical device for adjusting the electrode spacing has been abolished.
  • electrode spacing in operating commercial furnaces is critical. Therefore it is kept constant within rather narrow limits i /z cm.).
  • my electrodes are stationary; they are partially combusted or consumed during operation (while electrode spacing increases), and periodically and conveniently integrated in situ.
  • Anodic faces, in the new cell, are virtually equal to cathodic faces while, in conventional cells, they are about 50% to 60% of the cathodic area.
  • the electric resistance in the contact layer between anode and bath can be reduced and, at the same time, the necessary conditions are created in order that conventional anodic current densities may be considerably lowered.
  • current density amperage per unit cross-sectional area
  • current (amperage) ohmic voltage drops in the anode can be reduced to very low figures on account of the metallic stubs being stationary. Consequently their layout may be easily planned for most convenient dimensions.
  • the head of molten metal in known commercial furnaces is partially isolated from the cathodic carbon bottom by thick bath-crusts (rich in alumina and but slightly soluble), and by carbides (originating from irregular furnace operation, local superheatings), etc.
  • the above-described furnace may be conveniently' heated by means of an auxiliary heat source, since heat developed by the passage of the current through the electrodes and bath will not, as a rule, be sufi'icient. in other words, the total external surface of the furnace may actually turn out to be too great for the small amount of kwh. or of calories/hr. to be dissipated. If heat dissipation is to be balanced with or reduced tothe amount of available calories, one may operate with high current densities, or adequate insulation (either very bulky or particularly efiicient) may be provided, or an additional heat source, other than the electrolytic current, may be resorted to. External heating may be used especially for small furnaces of the new type herein disclosed, eg. for laboratory pots.
  • references (a) describes a range of 900-1000 C.
  • reference (17) an operating range just under 1000 0.
  • reference (0) states that the temperature of the electrolyte should be between 930 to 950 C.
  • reference (e) states that the electrolytic production of aluminum from a fused cryolite bath is carried out at a temperature between 950 and 1000 C.
  • the concentration of A1 0 in the bath is also conventional.
  • a new alumina charge is fed in when the alumina content of the bath drops below a certain percentage, such as 3 to 5 percent. This is common practice, and is described in references (a), and
  • the bath composition is also conventional. As stated above, it comprises molten cryolite containing dissolved alumina. It is common practice to add small amounts of other substances to increase current efliciency.
  • Various bath compositions are disclosed in references (a),
  • FIGS. 3 and 4 show a longitudinal section in a vertical plane and a plan view, respectively, of my multiple furnace such as it may preferably, but not solely, be built for industrial purposes.
  • the multiple furnace may be schematically represented as a set of elementary furnaces, or elements of FIG. 2, from which refractory and insulating head walls together with their metallic conductors (bars, nipples or stubs) have been removed. ()nly the two ends of the multiple furnace, of course, maintain said insulating and refractory head walls with the metallic fittings conducting the current.
  • FIG. 3 In FIG. 3 are shown the upper gas-chambers 12, the electrolytic gaps 13 and the lower metal-chambers 14. Near one end of the elongated multiple furnace the cathodic carbon 1'5 and, at the oppositeend, the anodic carbon 16 are shown, both carbons being connected with their respective terminal bars 21 by means of iron stubs 17.
  • the cover is fragmentarily indicated at 2? in FIG. 1.
  • the gas outlets are shown at 30.
  • the bath-resistant and insulating layer 18 will, here also, line the inside walls of the lower chambers as well as the sides of the cells.
  • Carbon blocks 27 spaced between the nipple-fitted end electrodes are nippleless themselves and will act as anodes on their sloping surfaces facing the cathodic electrode 15 and as cathodes on their other sloping, and parallel surface, facing the anode 16.
  • Graphite as is known, is more expensive than carbon agglomerates for electrodes, is a better electrical conductor, will offer a greater resistance to oxidizing gases, etc. On the other hand, it requires higher decomposition voltage when in contact with the electrolytic bath and, consequently, a higher unit power consumption per kg. of produced aluminum.
  • the intermediate electrodes 27, instead of being carbon only, may be entirely of graphite or partly of graphite, viz. graphite-covered as far as the cathodic portion is concerned.
  • the dotted line 25 represents the contact surface between the old anode and the newly applied one.
  • the anode surfaces are renewed in situ when necessary as described above in connection with FIGS. 5 and 6.
  • Both the refractory layer Ztl, preferably of calcinated magnesite, and the insulating layer 19, preferably containing alumina, are enclosed in an iron casing 28.
  • the channels 22 at the bottom of lower chambers are normally plugged shut with refractory material of known composition. Through these channels the aluminum 23 which collects in a layer underneath the liquid bath 24, may be tapped.
  • the lower chambers are separated from one another by means of bathproof little partitions 26 which are entirely made up of, or simply lined with, the abovementioned bath and metal-resistant material 18.
  • FIG. 3 neither a cover, nor exhaust ducts for electrolytic gases and for vapours which develop when the anodic binding material is baked, nor alumina layers being preheated, are shown.
  • FIG. 7 the upper chamber of an open multiple furnace is shown.
  • partition walls dividing said chamber into a number of individual compartments, one for each cell, are not shown in the drawings, said partitions resting on the electrodic carbons and joining obviously both sidewalls of the multiple furnace.
  • the process may advantageously be carried out, according to this invention, with such a succession of respective electrolysis periods that the stages of electrolysis in adjacent cells are substantially different from each other.
  • the way each element, as well as the multiple furnace as a whole, operates, is similar to the operation of the elementary furnace previously described. In comparison with the latter, however, notable advantages are attained:
  • the daily metal output is many times as much as that of the elementary cell, in fact it may go up, for instance, from between 13 to 14 to between to 200 kg. of aluminum in 24 hours if a I l-element multiple furnace having electrodes of the size stated above is employed.
  • a further reduction of power consumption will be obtained.
  • the unit consumption of from 11 to 15 kwh./ kg. of aluminum goes down to 9 to 13 kwh./ kg. of aluminum, owing to the fact that the ohmic voltage drops in the nipples and in their contact with the two-end carbons are subdivided over a greater number of elementary furnaces, and probably owing also to other reasons.
  • the resulting voltage dropsin the cells having the nippled electrodes are less than 4.5 volts and 3.8 volts, respectively; and the voltage drops in the intermediate cells are less than 4.0 volts and 3.3 volts, respectively.
  • the power consumption drops to below 16 kwh., preferably below 13 kwh. per kg. of metal output.
  • the new multiple furnace possesses such structural and constructional features as to cut heat-losses down with respect to conventional furnaces, no overly-thick outer heat insulation layers being needed to achieve this end.
  • My cell will dissipate, through upper anodic surfaces, about half as much heat, for instance, as conventional ones (not even considering dissipation from the nipples, etc).
  • Advantagcs The possibility of operating at lower total and unit amperages, reduced kWh/kg. Al consumption, greater regularity in operation, etc. (4)
  • the alumina charged, in the new furnace will usually be higher than grams per square centimeter of open bath surface and may be even higher than gr./ sq. cm.
  • the layer of alumina In commercial furnaces, the layer of alumina is usually less than 19 gr./sq. cm. thick. As already described, this increased thickness will favorably erlect heat insulation, without, on the other hand, the increased alumina charge per bath surface unit causing diificulties.
  • the baths in conventional known cells are not deeper than to cm. for constructional, operating and cost reasons. My furnace can easily attain bath-depths of 50 cm. or more, without consideration of the bath-layer in the lower chamber, which varies, for instance, between 10 to 30 cm. in depth.
  • the downward velocity of alumina must also be taken into consideration. It is low enough, as a rule (a few centimeters per minute), so that the charge may dissolve in the bath before reaching the metal layers and settle onto the cell-bottom of the known types of furnaces.
  • Another feature of the new cell consists in the fact that the electrolytic gases, developing from a smaller bath-surface (per kg. of Al output), are easier to dispose of, and their flow outwards is intensive enough to prevent leakage into the cell, during electrolysis, of the air.
  • Power consumption, in the multiple furnace, is surprisingly low; from 9 to '13 'kwh. per kg. of Al output.
  • the sloping cathodic face will help to convey molten aluminum downwards; a thin liquid metal film at most, will build up over it, but in no case will a layer having a thickness measured in centimeter cover the cathode.
  • a series multicell furnace for fused salt electrolysis of compounds reacting by electrolysis with consumable anodes comprising more than two stationary carbon electrodes, including two terminal carbon electrodes and at least one intermediate bi polar carbon electrode defining a plurality of individual electrolysis cells in series, each cell having electrodic surfaces inclined to the vertical and to the horizontal and facing each other, substantially coextensive and substantially parallel to each other to form a slanting laterally confined electrolysis gap, the inclined anode surfaces facing downwardly, and an individual collecting chamber below each gap and communicating therewith, the chambers being separated by electrically insulating partition wall means, and current supply means connected with the two terminal electrodes.
  • a series multicell furnace for fused salt electrolysis of aluminum compounds reacting with consumable anodes comprising a stationary carbon end anode and a carbon end cathode and having respective substantially congruent and substantially parallel elcctrodic surfaces inclined to the vertical and defining an intermediate space, at least one stationary intermediate bipolar carbon electrode member disposed in said space, each of said intermediate electrode members having a pair of faces substantially paralle.
  • said anode and said cathode defining together with said intermediate electrodes a plurality of inclined laterally confined gaps adapted to receive electrolyte, the inclined anode surface facing downwardly, a substantially inert, current insulating and heat resistant container housing said anode and said cathode and said intermediate electrode members, said housing providing a plurality of lower insulated chambers, an individual one thereof being below each of said plurality of gaps and communicating with respective ones thereof for recei ing molten aluminum, substantially inert heat-resistant and current insulating partition means in the lower part of said housing supporting the lower end of each of the bipolar electrodes and separating the lower portions of the cells from one another to define individual electrolytic cells and to provide said plurality of insulated chambers, and means for applying a source of current only to said anode and said cathode, the end anode, cathode, intermediate carbon electrode, and gaps being in electrical series.
  • I 5 In a process for the production of aluminum by fused salt electrolysis of aluminum oxide reacting by electrolysis with a consumable anode, which comprises feeding said aluminum oxide during electrolysis into a furnace cell comprising a gap inclined to the vertical, the gap being defined by a downwardly facing stationary anodic carbon electrode and an upwardly facing cathodic carbon electrode and containing fused cryolite as electrolyte, the improvement comprising collecting below the gap the molten aluminum flowing as it is forming from the cathodic electrode, gradually diminishing the current intensity passing through said fixed electrodes as the gap spacing between said electrodes increases due to the electrolytic oxidation of said anodic carbon, periodically draining the collected aluminum and draining the electrolyte from the gap, renewing said anodic carbon, in situ from the bath-side, by securing a new anodic surface portion thereagainst after said electrolyte is drained, refilling said gap with cryolite electrolyte and continually repeating tht abovcdefined steps.
  • a series multi-cell furnace for fused salt electrolysis, of aluminum compounds reacting with consumable anodes comprising a stationary carbon end anode and a carbon end-cathode having respective substantially parallel electrodic surfaces inclined with respect to the vertical and defining an intermediate space, said endanode surface facing downwardly and said end-cathode surface upwardly at least one stationary intermediate carbon electrode member disposed in said space, each of said intermediate electrode members having a pair of opposed, substantially parallel faces aligned parallel with respect to said surfaces, said end anode and said end cathode defining together with said intermediate electrodes a plurality of inclined laterally confined gaps adapted to receive electrolyte, the end anode, cathode, intermediate carbon electrode, and gaps being in electrical series, a plurality of individual, electrically insulated chambers, one below each of said gaps and each communicating with a respective one thereof for receiving molten aluminum separately from each gap, and means for applying a source of current to said end anode and said end cathode.
  • said restoring of the stationary anodic electrode comprising the steps of fixing a carbon plate against the anodic surface by means of a paste becoming electrically conductive under the action of heat, returning the fused bath to the cell, and again setting said cell into operation whereupon the ohmic heat developed by current will complete the cokification of said paste to a solid layer which unifies said integrated anode.
  • said restoring of the stationary anodic electrode comprising the steps of fixing a plurality of planar strips of carbon side-byside against the anodic surface by means of a paste be coming electrially conductive under the action of heat returning the fused bath to the cell, and finally setting 15 said cell into operation whereupon the ohmic heat developed by current will complete the colcification of said paste to a solid layer which unifies said integrated anode.
  • electrolysis is carried out in a furnace comprising a plurality of cells formed by at least one stationary intermediate bipolar having a graphite cathode portion carbon electrode and by a stationary nippled end carbon anode and a stationary nippled end graphite cathode defining the respective gaps, with such a succession of respective electrolysis periods that the stages of electrolysis in adjacent cells are substantially different from each other.
  • the process for the production of a metal by fused salt electrolysis of a compound reacting by electrolysis with a consumable anode, in a furnace cell having staiffy electrodes forming an inclined laterally confined electrodic gap containing electrolyte which comprises supplying electric current in substantially uniform distribution, respectively, over the surfaces of the anode and of the cathode defining said gap, feeding said compound into said furnace cell, removing from the gap the resulting metal by specific gravity difference, and restoring the anodic electrode in situ, from the bath side.
  • a multicell furnace for metal production from its oxide by a fused salt bath electrolysis in which anodic carbon is consumed comprising a housing containing electrode structures comprising a stationary anode terminal alement and a stationary cathode terminal element spaced apart in said housing, and at least one bipolar electrode structure stationed in said furnace between and spaced from said anode and cathode terminal elements, said bipolar electrode structure having opposite anode and stationary cathode polar faces, the electrode structures providing pairs of opposite bath-facing cathodic and anodic surfaces, each pair taken together with an intervening electrolysis gap forming a cell, there being at least two of said gaps providing at least two of said cells, the gaps extending generally upwardly-downwardly, means for passing electric current serially through the electrode structures and intervening electrolysis gaps, and consequently serially through said cells, means comprising part of said electrode structures and forming a renewal structure of carbonaceous material consumable in the electrolysis positioned adjacent individual anode faces of said electrode structures, the renewal structure providing a
  • a multicell furnace for production of aluminum by fused salt bath electrolysis of alumina comprising a housing containing electrode structures comprising a stationary anode terminal element and a stationary cathode terminal element spaced apart in said housing, and at least one bipolar electrode structure stationed in said furnace between and spaced from said anode and cathode terminal elements, said bipolar electrode structure having opposite anode and stationary cathode polar faces, the electrode structures providing pairs of opposite bathfacing cathodic and anodic surfaces, each pair taken together with an intervening electrolysis gap forming an individual, laterally confined cell, there being at least two of said gaps providing at least two of said cells, the gaps extending generally upwardly-downwardly, means for passing electric current serially through the electrode structures and intervening electrolysis gaps, and consequently serially through said cells, means comprising part of said electrode structures and forming a renewal structure of carbonaceous material consumable in the electrolysis positioned adjacent individual anode faces of said electrode structures, the renewal structure providing a generally downwardly-facing,

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NL (2) NL109009C (en))

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US3294656A (en) * 1961-10-17 1966-12-27 Alusuisse Method of producing aluminium
US3352767A (en) * 1962-11-10 1967-11-14 Montedison Spa Multicell electrolytic furnace with suspended electrodes and method of aluminum production
US6082807A (en) * 1997-06-11 2000-07-04 Grammer Formteile Gmbh Covering arrangement such as a soft top for a motor vehicle
CN114502777A (zh) * 2019-09-24 2022-05-13 俄罗斯工程技术中心有限责任公司 铝罐底预热方法

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Publication number Priority date Publication date Assignee Title
US2959527A (en) * 1957-01-05 1960-11-08 Montedison Spa Self-restoring anode in multi-cell furnaces particularly for the electrolytic production of aluminum
BE564404A (en)) * 1957-01-31
DE1758149C2 (de) * 1968-04-10 1974-07-25 Vereinigte Aluminium-Werke Ag, 5300 Bonn Vorrichtung zur Verbesserung des Wärmehaushalts von Aluminium-Elektrolysezellen neuzeitlicher Bauart mit vorgebrannten, kontinuierlichen Anoden
CN115072819B (zh) * 2022-05-19 2023-05-09 北京高能时代环境技术股份有限公司 用于原位热脱附-电催化氧化的电极井智能控制系统及修复系统

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DE58956C (de) * SOCIETE ELECTRO-METALLURGIQUE FRANCAISE, Direktor A. MASSE in Paris, 43 Rue St. Georges Verfahren zur Herstellung einer Kohlen-Elektrode aus einzelnen Kohlenplatten
US559729A (en) * 1896-05-05 Renzj
US1545384A (en) * 1923-01-11 1925-07-07 Ashcroft Edgar Arthur Apparatus for electrolyzing fused salts
US1545383A (en) * 1922-02-18 1925-07-07 Ashcroft Edgar Arthur Apparatus for electrolyzing fused salts
US2480474A (en) * 1945-12-14 1949-08-30 Reynolds Metals Co Method of producing aluminum
FR1061906A (fr) * 1951-08-03 1954-04-16 British Aluminium Co Ltd Cuves verticales pour la production de l'aluminium

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Publication number Priority date Publication date Assignee Title
DE58956C (de) * SOCIETE ELECTRO-METALLURGIQUE FRANCAISE, Direktor A. MASSE in Paris, 43 Rue St. Georges Verfahren zur Herstellung einer Kohlen-Elektrode aus einzelnen Kohlenplatten
US559729A (en) * 1896-05-05 Renzj
US1545383A (en) * 1922-02-18 1925-07-07 Ashcroft Edgar Arthur Apparatus for electrolyzing fused salts
US1545384A (en) * 1923-01-11 1925-07-07 Ashcroft Edgar Arthur Apparatus for electrolyzing fused salts
US2480474A (en) * 1945-12-14 1949-08-30 Reynolds Metals Co Method of producing aluminum
FR1061906A (fr) * 1951-08-03 1954-04-16 British Aluminium Co Ltd Cuves verticales pour la production de l'aluminium

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3294656A (en) * 1961-10-17 1966-12-27 Alusuisse Method of producing aluminium
US3352767A (en) * 1962-11-10 1967-11-14 Montedison Spa Multicell electrolytic furnace with suspended electrodes and method of aluminum production
US6082807A (en) * 1997-06-11 2000-07-04 Grammer Formteile Gmbh Covering arrangement such as a soft top for a motor vehicle
CN114502777A (zh) * 2019-09-24 2022-05-13 俄罗斯工程技术中心有限责任公司 铝罐底预热方法

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BE534969A (en))
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CH354258A (de) 1961-05-15
DE1146260B (de) 1963-03-28
NL194105A (en))

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