EP0073735A2 - Electrolytic pot for the production of aluminium by electrolysis in the dry way, and method of inserting the iron bars - Google Patents

Electrolytic pot for the production of aluminium by electrolysis in the dry way, and method of inserting the iron bars Download PDF

Info

Publication number
EP0073735A2
EP0073735A2 EP82810344A EP82810344A EP0073735A2 EP 0073735 A2 EP0073735 A2 EP 0073735A2 EP 82810344 A EP82810344 A EP 82810344A EP 82810344 A EP82810344 A EP 82810344A EP 0073735 A2 EP0073735 A2 EP 0073735A2
Authority
EP
European Patent Office
Prior art keywords
iron bars
electrolysis
iron
carbon
cross
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.)
Granted
Application number
EP82810344A
Other languages
German (de)
French (fr)
Other versions
EP0073735B1 (en
EP0073735A3 (en
Inventor
Raoul Jemec
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.)
Alcan Holdings Switzerland AG
Original Assignee
Alusuisse Holdings AG
Schweizerische Aluminium AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Alusuisse Holdings AG, Schweizerische Aluminium AG filed Critical Alusuisse Holdings AG
Priority to AT82810344T priority Critical patent/ATE16202T1/en
Publication of EP0073735A2 publication Critical patent/EP0073735A2/en
Publication of EP0073735A3 publication Critical patent/EP0073735A3/en
Application granted granted Critical
Publication of EP0073735B1 publication Critical patent/EP0073735B1/en
Expired legal-status Critical Current

Links

Images

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
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes

Definitions

  • the present invention relates to an electrolysis trough for the production of aluminum by means of melt flow electrolysis, consisting of an outer steel trough, a heat-insulating layer and an electrically conductive inner lining resistant to the molten material made of carbon blocks running in the transverse direction with solid iron bars protruding on both sides from the end faces , as well as a process for inserting the iron bars.
  • the inner lining of electrolysis tanks consists of carbon blocks, in which at least one continuous or in the middle separated iron bars is arranged. To minimize the voltage drop in the cell the electrical transition resistance between the iron ingot and the carbon block must be as small as possible.
  • the carbon blocks and iron bars can be found in conventional electrolysis tanks in various dimensions in terms of length, width and height as well as groove shapes.
  • the technique of pouring is widely used today to create the connection between the carbon block and the iron ingot.
  • the iron bars placed in the groove of the carbon block are connected to the carbon by casting with cast iron.
  • Iron ingot and carbon block are preheated together and cooled down to the ambient temperature after pouring. Since the thermal expansion or contraction of iron is approximately four times greater than that of carbon, a gap is created when cooling between carbon and cast iron. If the carbon block provided with an iron bar is installed in an electrolysis cell, this gap only closes during the rise in temperature when the electrolysis cell is started up, which improves the electrical and mechanical contact between iron and carbon. If the gap formed by the contraction is closed before the working temperature is reached, the iron bar, which is expanding more rapidly, can act so strongly on the carbon of the cathode elements that cracks can occur in the cathode.
  • the cast iron has the disadvantage that it has a relatively low electrical conductivity. Furthermore, with conventional cast iron bars, the contact pressure in the uppermost area of the bar in the working position is often insufficient, so that it is not sufficient to produce the desired low electrical transition resistance from carbon to iron. In this case, the electric current does not flow the shortest way through the carbon base of the electrolysis tank, but makes a detour by not entering the top surface but the side surfaces of the iron bar. The two factors mentioned can cause a voltage drop of up to 0.1 volt, for example, which has a negative effect on the energy balance of the electrolysis cell.
  • the iron ingot should be fully connected to the carbon at working temperature. In practice, this can hardly be done.
  • the electrical transition resistance from graphite to iron is too high or cracks occur in the graphite block, which reduce the life span of the electrolysis tub to an unacceptable extent.
  • the inventor has set himself the task of avoiding the aforementioned disadvantages of pouring iron bars into carbon blocks without impairing the life of the electrolysis tank, but reducing the transition resistance from carbon to iron bars.
  • the groove with the usual dimensions of carbon block and iron ingot, can be expanded by about 1 mm at its lower opening before the cracking in the carbon begins or even a carbon flap breaks off.
  • a certain elasticity of the carbon blocks is essential when anchoring the iron bars without pouring them in.
  • the preferred temperature of about 700 ° C At this temperature, the groove and the iron bar inserted therein have exactly the same cross-section, i.e. the iron bar lies full on the carbon along its entire circumference, but without exerting any pressure on it.
  • the iron ingot presses on the carbon. Thanks to the elasticity of the expanding carbon lobes, however, there are no cracks, as would be the case if a hole were formed instead of a groove.
  • the iron bars can extend in a manner known per se over the entire length of the carbon blocks or can be severed in the middle, with a smaller or greater distance. It is known that in the melt flow electrolysis of aluminum most of the electrical current flows in the outer area of the iron bars of the electrolysis tank. It is therefore sufficient if the iron bars are formed from both ends of the carbon blocks up to at least 20% each with respect to the length of the carbon blocks towards the center of the tub. In the center of the carbon blocks, the iron bars can be separated up to 60% of the length of the blocks.
  • the grooves can extend over the entire length of the carbon block or over a part thereof corresponding to the iron ingot, the end walls of the iron ingot and groove being separated by a preferably 0.5-1 cm wide cavity.
  • the iron bars which preferably protrude about 0.5-1.5 cm from the bottom surface of the carbon blocks, and the correspondingly recessed groove can have any practical geometric shape.
  • iron bars and the corresponding groove preferably have rounded cross sections, at least in their upper region in relation to the working position. This has the essential advantage that when the flaps of the carbon block laterally surrounding the iron bars are spread, the notch effect is reduced, ie in the case of In the upper area of the rounded grooves, the crack formation only begins with greater pressure from the iron bar than would be the case with angular grooves.
  • the essential feature of the method according to the invention for inserting the iron bars in an electrolysis tank with correspondingly recessed grooves which are open downwards in the working position is that the iron bars are pushed into the interior of the electrolysis tank through bar windows in the steel tank at ambient temperature.
  • These bar windows expediently have the same geometric shape as the cross section of the iron bars. These bar windows are preferably only a little, in particular 0.5-2 cm, larger than the linear dimensions of the iron bar cross sections, ie the iron bars become with little play through the parallel bars into the tub. In this case, the joints are easy to seal.
  • iron bars are rectangular at least in the lower area or tapered towards the top, they can be placed on the insulation layer in accordance with the shaped grooves. The carbon block is then lowered onto them.
  • the invention is explained in more detail with reference to the embodiment shown in the drawing.
  • the single figure shows a schematic vertical section through a carbon block with two iron bars in the working position, but before the complete lowering.
  • the carbon block 10 which is rectangular in cross section, contains the round iron bars 12 which run parallel in the longitudinal direction in correspondingly shaped grooves 14 which are partially open at the bottom.
  • Each tab 16 of the carbon block 10 comprises the iron bars 12 in a U-shape. If the iron bars 12 exert pressure on the carbon block 10 at working temperature, this is absorbed by the Tabs 16 are spread apart accordingly.
  • the edges 18 of these tabs 16 are preferably rounded or cut off.
  • the carbon block 10 inserted into the electrolysis trough lies along the surface lines 20 of the iron bars 12 on the insulation layer (not shown).
  • the iron bars 12 are pressed flatly in their upper area onto the corresponding area of the grooves 14, the transition resistance from carbon to iron is minimal as a result.
  • the direct electric current can flow directly from the top surface of the carbon block 10 and with a low transition resistance in the direction of the arrows to the iron bar 12.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

1. A reduction pot for the production of aluminium by means of fusion electrolysis, consisting of an outer steel shell, a thermally insulating layer and an electrically conductive inner lining which is resistant to the molten charge and is made up of carbon blocks (10) running in the transverse direction and having running in their longitudinal direction grooves (14) which are open downwards and extend over at least 20% of the length - starting from the two endfaces - and in which are inserted solid iron bars (12) which project downwards out of the bottom face and on both sides out of the endfaces of the carbon blocks, where part of the weight of the carbon blocks (10) is borne approximately uniformly by all of the iron bars (12) projecting out of their bottom faces, characterized in that the grooves (14) in the carbon blocks (10) have cross-sections which at a temperature between 500 and 850 degrees C correspond exactly with the cross-section of the iron bars (12) heated to the same temperature.

Description

Die vorliegende Erfindung bezieht sich auf eine Elektrolysewanne zur Herstellung von Aluminium mittels Schmelzflusselektrolyse, bestehend aus einer äusseren Stahlwanne, einer wärmedämmenden Isolationsschicht und einer elektrisch leitenden, gegen das schmelzflüssige Material beständigen Innenauskleidung aus in Querrichtung verlaufenden Kohlenstoffblöcken mit eingesetzten, beidseitig aus deren Stirnseiten herausragenden massiven Eisenbarren, sowie auf ein Verfahren zum Einsetzen der Eisenbarren.The present invention relates to an electrolysis trough for the production of aluminum by means of melt flow electrolysis, consisting of an outer steel trough, a heat-insulating layer and an electrically conductive inner lining resistant to the molten material made of carbon blocks running in the transverse direction with solid iron bars protruding on both sides from the end faces , as well as a process for inserting the iron bars.

Für die Gewinnung von Aluminium durch Elektrolyse von Aluminiumoxid wird dieses in einer Fluoridschmelze gelöst, die zum grössten Teil aus Kryolith besteht. Das kathodisch abgeschiedene Aluminium sammelt sich unter der Fluoridschmelze auf dem Kohlenstoffboden der Zelle, wobei die Oberfläche des flüssigen Aluminiums die Kathode bildet. In die Schmelze tauchen von oben Anoden ein, die bei konventionellen Verfahren aus amorphem Kohlenstoff bestehen. Durch die elektrolytische Zersetzung des Aluminiumoxids entsteht Sauerstoff, der sich mit dem Kohlenstoff der Anoden zu C02 und CO verbindet. Die Elektrolyse findet in einem Temperaturbereich von etwa 940-970°C statt.For the production of aluminum by electrolysis of aluminum oxide, this is dissolved in a fluoride melt, which largely consists of cryolite. The cathodically deposited aluminum collects under the fluoride melt on the carbon bottom of the cell, the surface of the liquid aluminum forming the cathode. Anodes which consist of amorphous carbon in conventional processes are immersed in the melt. The electrolytic decomposition of the aluminum oxide produces oxygen, which combines with the carbon of the anodes to form CO 2 and CO. The electrolysis takes place in a temperature range of approximately 940-970 ° C.

Die Innenauskleidung von Elektrolysewannen besteht aus Kohlenstoffblöcken, in welchen mindestens ein durchgehender oder in der Mitte getrennte Eisenbarren angeordnet ist. Um zu einem möglichst geringen Spannungsabfall der Zelle beizutragen, muss der elektrische Uebergangswiderstand zwischen Eisenbarren und Kohlenstoffblock möglichst klein sein.The inner lining of electrolysis tanks consists of carbon blocks, in which at least one continuous or in the middle separated iron bars is arranged. To minimize the voltage drop in the cell the electrical transition resistance between the iron ingot and the carbon block must be as small as possible.

Dem Fachmann sind verschiedene Arten zur Verbindung von Kohlenstoffblock und Eisenbarren bekannt, beispielsweise

  • - Einstampfen mit einer Stampfmasse
  • - Eingiessen mit Gusseisen
  • - Einkleben.
Various ways of connecting carbon block and iron ingot are known to those skilled in the art, for example
  • - Pounding with a pounding compound
  • - Pour in with cast iron
  • - Glue in.

Die Kohlenstoffblöcke und die Eisenbarren finden sich in herkömmlichen Elektrolysewannen in verschiedensten Dimensionen in bezug auf Länge, Breite und Höhe sowie Nutformen.The carbon blocks and iron bars can be found in conventional electrolysis tanks in various dimensions in terms of length, width and height as well as groove shapes.

Beim Erstellen der Verbindung zwischen Kohlenstoffblock und Eisenbarren ist heute die Technik des Eingiessens weit verbreitet. Die in die Nut des Kohlenstoffblockes eingelegten Eisenbarren werden durch Umgiessen mit Gusseisen mit dem Kohlenstoff verbunden. Eisenbarren und Kohlenstoffblock werden gemeinsam vorgewärmt und nach dem Eingiessen auf die Umgebungstemperatur abgekühlt. Da die Wärmedehnung bzw. -kontraktion von Eisen ungefähr viermal grösser ist als diejenige von Kohlenstoff, entsteht bei der Abkühlung zwischen Kohlenstoff und Gusseisen ein Spalt. Ist der mit einem Eisenbarren versehene Kohlenstoffblock in eine Elektrolysezelle eingebaut, so schliesst sich dieser Spalt erst während des Temperaturanstiegs bei der Inbetriebnahme der Elektrolysezelle, womit der elektrische und mechanische Kontakt zwischen Eisen und Kohlenstoff verbessert wird. Wird der durch die Kontraktion gebildete Spalt vor dem Erreichen der Arbeitstemperatur geschlossen, so kann der sich schneller ausdehnende Eisenbarren derart stark auf die Kohle der Kathodenelemente einwirken, dass in der Kathode Risse entstehen können.The technique of pouring is widely used today to create the connection between the carbon block and the iron ingot. The iron bars placed in the groove of the carbon block are connected to the carbon by casting with cast iron. Iron ingot and carbon block are preheated together and cooled down to the ambient temperature after pouring. Since the thermal expansion or contraction of iron is approximately four times greater than that of carbon, a gap is created when cooling between carbon and cast iron. If the carbon block provided with an iron bar is installed in an electrolysis cell, this gap only closes during the rise in temperature when the electrolysis cell is started up, which improves the electrical and mechanical contact between iron and carbon. If the gap formed by the contraction is closed before the working temperature is reached, the iron bar, which is expanding more rapidly, can act so strongly on the carbon of the cathode elements that cracks can occur in the cathode.

Das Gusseisen weist den Nachteil auf, dass es eine verhältnismässig niedrige elektrische Leitfähigkeit hat. Weiter ist bei üblichen eingegossenen Eisenbarren der Anpressdruck im in Arbeitsposition obersten Bereich des Barrens oft ungenügend, so dass er nicht ausreicht, den erwünschten niedrigen elektrischen Uebergangswiderstand vom Kohlenstoff zum Eisen herzustellen. In diesem Fall fliesst der elektrische Strom nicht auf dem kürzesten Weg durch den Kohlenstoffboden der Elektrolysewanne, sondern macht einen Umweg, indem er nicht in die Deckfläche, sondern in die Seitenflächen des Eisenbarrens eintritt. Die beiden erwähnten Faktoren können einen Spannungsabfall z.B. bis zu 0,1 volt, bewirken, was sich in der Energiebilanz der Elektrolysezelle negativ niederschlägt. Schon vor einiger Zeit ist deshalb, wie im J. Electrochemical Technology, Vol. 5, No. 3-4 (1967), Seiten 152-154, beschrieben, versucht worden, einen Eisenbarren direkt mit dem Kohlenstoffblock in Verbindung zu bringen. Im Kohlenstoffblock wird ein dem Eisenbarren entsprechendes Loch ausgespart und dieser ohne Stampf-r Guss- oder Klebemasse hineingesteckt. Da aber in der verhältnismässig langen Zwischenzeit keine Schmelzflusselektrolysezellen zur Herstellung von Aluminium, die nach diesem Prinzip gebaut sind, bekannt geworden sind, hat sich das Verfahren offensichtlich nicht bewährt.The cast iron has the disadvantage that it has a relatively low electrical conductivity. Furthermore, with conventional cast iron bars, the contact pressure in the uppermost area of the bar in the working position is often insufficient, so that it is not sufficient to produce the desired low electrical transition resistance from carbon to iron. In this case, the electric current does not flow the shortest way through the carbon base of the electrolysis tank, but makes a detour by not entering the top surface but the side surfaces of the iron bar. The two factors mentioned can cause a voltage drop of up to 0.1 volt, for example, which has a negative effect on the energy balance of the electrolysis cell. Some time ago, as in J. Electrochemical Technology, Vol. 5, No. 3-4 (1967), pp. 152-154, attempts have been made to directly connect an iron ingot to the carbon block. In the carbon block, a corresponding iron bars hole is cut out and inserted this without ramming r cast or adhesive. However, since no melt-flow electrolysis cells for the production of aluminum, which are built according to this principle, have become known in the relatively long meantime, the method has obviously not proven itself.

Nach dieser Publikation müsste der Eisenbarren bei Arbeitstemperatur satt an den Kohlenstoff anschliessen. In der Praxis lässt sich dies kaum durchführen. Während des Elektrolyseprozesses ist bei kleinsten Ungenauigkeiten entweder der elektrische Uebergangswiderstand vom Graphit zum Eisen zu gross oder es entstehen im Graphitblock Risse, welche die Lebensdauer der Elektrolysewanne in untragbarem Masse erniedrigen.According to this publication, the iron ingot should be fully connected to the carbon at working temperature. In practice, this can hardly be done. During the electrolysis process, with the smallest inaccuracies, either the electrical transition resistance from graphite to iron is too high or cracks occur in the graphite block, which reduce the life span of the electrolysis tub to an unacceptable extent.

Der Erfinder hat sich die Aufgabe gestellt, die erwähnten Nachteile des Eingiessens von Eisenbarren in Kohlenstoffblöcke zu vermeiden, ohne die Lebensdauer der Elektrolysewanne zu beeinträchtigen, hingegen den Uebergangswiderstand vom Kohlenstoff zum Eisenbarren zu verkleinern.The inventor has set himself the task of avoiding the aforementioned disadvantages of pouring iron bars into carbon blocks without impairing the life of the electrolysis tank, but reducing the transition resistance from carbon to iron bars.

Die Aufgabe wird in bezug auf die Elektrolysewanne erfindungsgemäss dadurch gelöst, dass

  • - in jedem Kohlenstoffblock in dessen Längsrichtung über mindestens 20% der Länge, ausgehend von beiden Stirnseiten, in Arbeitsposition nach unten offene Nuten ausgespart sind, die in bezug auf den Querschnitt bei 500-850°C exakt dem Querschnitt der auf dieselbe Temperatur erwärmten Eisenbarren entsprechen,
  • - die in die Nuten eingesetzten, sich über mindestens 20% der Länge des Kohlenstoffblocks, ausgehend von den Stirnseiten, erstreckenden Eisenbarren während des Elektrolyseprozesses entlang der ganzen unteren Seitenfläche bzw. Mantellinie aus dem Kohlenstoffblock herausragen, und
  • - ein Teil des Gewichts der Kohlenstoffblöcke ungefähr gleichmässig auf allen Eisenbarren abgestützt ist.
The object is achieved according to the invention in relation to the electrolysis bath in that
  • - In each carbon block in the longitudinal direction over at least 20% of the length, starting from both ends, in the working position, open grooves are cut out, which correspond exactly to the cross-section at 500-850 ° C with respect to the cross-section of the iron bars heated to the same temperature ,
  • the iron bars inserted into the grooves and extending over at least 20% of the length of the carbon block, starting from the end faces, protrude from the carbon block along the entire lower side surface or surface line during the electrolysis process, and
  • - Part of the weight of the carbon blocks is supported approximately evenly on all iron bars.

Versuche haben gezeigt, dass sich die Nut, bei üblichen Dimensionen von Kohlenstoffblock und Eisenbarren, an deren unteren Oeffnung um ungefähr 1 mm spreizen lässt, bevor die Rissbildung im Kohlenstoff einsetzt oder gar ein Kohlenstofflappen abbricht. Eine gewisse Elastizität der Kohlenstoffblöcke ist beim Verankern der Eisenbarren ohne Eingiessen von wesentlicher Bedeutung.Tests have shown that the groove, with the usual dimensions of carbon block and iron ingot, can be expanded by about 1 mm at its lower opening before the cracking in the carbon begins or even a carbon flap breaks off. A certain elasticity of the carbon blocks is essential when anchoring the iron bars without pouring them in.

Dies soll anhand der bevorzugten Temperatur von etwa 700°C gezeigt werden: Bei dieser Temperatur haben die Nut und der darin eingesetzte Eisenbarren exakt den gleichen Querschnitt, d.h. der Eisenbarren liegt entlang seines ganzen Umfangs satt auf dem Kohlenstoff, jedoch ohne darauf einen Druck auszuüben. Bei höheren Temperaturen, über 700°C, beispielsweise bei der Aluminiumelektrolyse-Temperatur von 940-970°C, drückt der Eisenbarren auf den Kohlenstoff. Dank der Elastizität der sich spreizenden Kohlenstofflappen entstehen jedoch keine Risse, wie dies bei der Ausbildung eines Loches statt einer Nut der Fall wäre.This should be shown by the preferred temperature of about 700 ° C: At this temperature, the groove and the iron bar inserted therein have exactly the same cross-section, i.e. the iron bar lies full on the carbon along its entire circumference, but without exerting any pressure on it. At higher temperatures, above 700 ° C, for example at the aluminum electrolysis temperature of 940-970 ° C, the iron ingot presses on the carbon. Thanks to the elasticity of the expanding carbon lobes, however, there are no cracks, as would be the case if a hole were formed instead of a groove.

Ein Teil des Gewichts der Kohlenstoffauskleidung ist ungefähr gleichmässig auf die aus den Kohlenstoffblöcken herausragenden Eisenbarren verteilt. Dadurch drücken diese Eisenbarren in Arbeitsposition auf den entsprechend geformten oberen Bereich der Nut, auch wenn der Querschnitt des Eisenbarrens kleiner als derjenige der Nut ist. Dieser Flächendruck hat zur Folge, dass ein möglichst kleiner Uebergangswiderstand vom Kohlenstoff zum Eisen in jenem Bereich entsteht, der dem die Kathode der Elektrolysezelle bildenden flüssigen Aluminium am meisten benachbart ist. Der Der Spannungsabfall wird also in bezug auf zwei Faktoren minimalisiert:

  • - Uebergangswiderstand Kohlenstoff - Eisen
  • - Spannungsabfall in der Kohlenstoffauskleidung der Elektrolysewanne.
Part of the weight of the carbon lining is approximately evenly distributed over the iron ingots protruding from the carbon blocks. As a result, these iron bars press into the correspondingly shaped upper area of the groove in the working position, even if the cross section of the iron bar is smaller than that of the groove. This surface pressure has the result that the smallest possible transition resistance from carbon to iron arises in the area which is most adjacent to the liquid aluminum forming the cathode of the electrolytic cell. The The voltage drop is therefore minimized in relation to two factors:
  • - transition resistance carbon - iron
  • - Voltage drop in the carbon lining of the electrolysis bath.

Die Eisenbarren können sich auf an sich bekannte Weise über die gesamte Länge der Kohlenstoffblöcke erstrecken oder in der Mitte, mit kleinerem oder grösserem Abstand, durchtrennt sein. Es ist bekannt, dass bei der Schmelzflusselektrolyse von Aluminium der grösste Teil des elektrischen Stromes im äusseren Bereich der Eisenbarren der Elektrolysewanne abfliesst. Es genügt deshalb, wenn die Eisenbarren von beiden Stirnseiten der Kohlenstoffblöcke her bis mindestens je 20% in bezug auf die Länge der Kohlenstoffblöcke zur Wannenmitte hin ausgebildet sind. Im Zentrum der Kohlenstoffblöcke können die Eisenbarren folglich bis zu 60% der Länge der Blöcke getrennt sein. Die Nuten können sich über die gesamte Länge des Kohlenstoffblockes oder über einen den Eisenbarren entsprechenden Teil davon erstrecken, wobei die Stirnwände von Eisenbarren und Nut durch einen vorzugsweise 0,5-1 cm breiten Hohlraum getrennt sind.The iron bars can extend in a manner known per se over the entire length of the carbon blocks or can be severed in the middle, with a smaller or greater distance. It is known that in the melt flow electrolysis of aluminum most of the electrical current flows in the outer area of the iron bars of the electrolysis tank. It is therefore sufficient if the iron bars are formed from both ends of the carbon blocks up to at least 20% each with respect to the length of the carbon blocks towards the center of the tub. In the center of the carbon blocks, the iron bars can be separated up to 60% of the length of the blocks. The grooves can extend over the entire length of the carbon block or over a part thereof corresponding to the iron ingot, the end walls of the iron ingot and groove being separated by a preferably 0.5-1 cm wide cavity.

Die vorzugsweise etwa 0,5-1,5 cm aus der Bodenfläche der Kohlenstoffblöcke herausragenden Eisenbarren und die entsprechend ausgesparte Nut können jede zweckmässige geometrische Form haben. Bevorzugt haben jedoch Eisenbarren und entsprechende Nut, mindestens in ihrem in bezug auf die Arbeitsposition oberen Bereich, abgerundete Querschnitte. Dies bringt den wesentlichen Vorteil, dass beim Spreizen der den Eisenbarren seitlich umgebenden Lappen des Kohlenstoffblocks die Kerbwirkung herabgesetzt wird, d.h. bei im oberen Bereich abgerundeten Nuten setzt die Rissbildung erst bei grösserem Druck durch den Eisenbarren ein, als dies bei eckig ausgebildeten Nuten der Fall wäre.The iron bars, which preferably protrude about 0.5-1.5 cm from the bottom surface of the carbon blocks, and the correspondingly recessed groove can have any practical geometric shape. However, iron bars and the corresponding groove preferably have rounded cross sections, at least in their upper region in relation to the working position. This has the essential advantage that when the flaps of the carbon block laterally surrounding the iron bars are spread, the notch effect is reduced, ie in the case of In the upper area of the rounded grooves, the crack formation only begins with greater pressure from the iron bar than would be the case with angular grooves.

Insbesondere Eisenbarren mit kreisrundem Querschnitt und entsprechend geformte Nuten sind vorteilhaft, weil

  • - runde Barren die kleinste Oberfläche bei konstantem Querschnitt haben, was gleiche elektrische Leitfähigkeit bei geringeren Wärmeverlusten bedeutet,
  • - die Festigkeit des Blockes wesentlich erhöht wird, da keine Kerbwirkung vorhanden ist,
  • - wegen des höheren maximalen Anpressdrucks der elektrische Kontaktwiderstand vom Kohlenstoff zum Eisen verringert werden kann,
  • - aus der Stahlwanne einfache runde Barrenfenster ausgespart werden können, die mit vorfabrizierten Materialien leicht zu verdichten sind, und
  • - die Fertigung der Barren besonders einfach ist.
In particular, iron bars with a circular cross section and appropriately shaped grooves are advantageous because
  • - round bars have the smallest surface with a constant cross-section, which means the same electrical conductivity with less heat loss,
  • the strength of the block is increased significantly since there is no notch effect,
  • - because of the higher maximum contact pressure, the electrical contact resistance from carbon to iron can be reduced,
  • - simple round ingot windows can be left out of the steel tub, which are easy to compress with prefabricated materials, and
  • - The manufacture of the bars is particularly simple.

Das wesentliche Merkmal des erfindungsgemässen Verfahrens zum Einsetzen der Eisenbarren in einer Elektrolysewanne mit entsprechend ausgesparten in Arbeitsposition nach unten offenen Nuten besteht darin, dass die Eisenbarren durch Barrenfenster in der Stahlwanne bei Umgebungstemperatur in den Innenraum der Elektrolysewanne geschoben werden.The essential feature of the method according to the invention for inserting the iron bars in an electrolysis tank with correspondingly recessed grooves which are open downwards in the working position is that the iron bars are pushed into the interior of the electrolysis tank through bar windows in the steel tank at ambient temperature.

Zweckmässig haben diese Barrenfenster die gleiche geometrische Form wie der Querschnitt der Eisenbarren. Vorzugsweise sind diese Barrenfenster nur wenig, insbesondere 0,5-2 cm, grösser als die linearen Dimensionen der Eisenbarrenquerschnitte, d.h. die Eisenbarren werden mit nur wenig Spiel durch die Barrenfenster in das Wanneninnere geführt. In diesem Fall sind die Fugen einfach abdichtbar.These bar windows expediently have the same geometric shape as the cross section of the iron bars. These bar windows are preferably only a little, in particular 0.5-2 cm, larger than the linear dimensions of the iron bar cross sections, ie the iron bars become with little play through the parallel bars into the tub. In this case, the joints are easy to seal.

Sind die Eisenbarren mindestens im unteren Bereich rechteckig oder sich nach oben verjüngend ausgebildet, so können sie, entsprechend den ausgeformten Nuten, auf die Isolationsschicht gelegt werden. Anschliessend wird der Kohlenstoffblock auf sie abgesenkt.If the iron bars are rectangular at least in the lower area or tapered towards the top, they can be placed on the insulation layer in accordance with the shaped grooves. The carbon block is then lowered onto them.

Bevorzugt werden jedoch bei allen Barrenquerschnitten, bei im Querschnitt runden Eisenbarren ist dies aus geometrischen Gründen meist notwendig, die Kohlenstoffblöcke bis wenig, beispielsweise etwa 0,5-2,5 cm, über die Isolationsschicht abgesenkt, dann die Eisenbarren in die Nuten geschoben, und schliesslich die Kohlenstoffblöcke vollständig abgesenkt. Diese liegen nun auf den Eisenbarren, die aus den Nuten herausragen.However, preference is given to all bar cross-sections, in the case of iron bars that are round in cross section, this is usually necessary for geometric reasons, the carbon blocks are lowered a little, for example about 0.5-2.5 cm, over the insulation layer, then the iron bars are pushed into the grooves, and finally the carbon blocks are completely lowered. These are now on the iron bars that protrude from the grooves.

Die Erfindung wird anhand des in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert. Die einzige Figur zeigt einen schematischen Vertikalschnitt durch einen Kohlenstoffblock mit zwei Eisenbarren in Arbeitsposition, jedoch vor dem vollständigen Absenken.The invention is explained in more detail with reference to the embodiment shown in the drawing. The single figure shows a schematic vertical section through a carbon block with two iron bars in the working position, but before the complete lowering.

Der im Querschnitt rechteckige Kohlenstoffblock 10 enthält die parallel in Längsrichtung verlaufenden runden Eisenbarren 12 in entsprechend ausgeformten, nach unten teilweise offenen Nuten 14. Je zwei Lappen 16 des Kohlenstoffblocks 10 umfassen die Eisenbarren 12 U-förmig. Wenn die Eisenbarren 12 bei Arbeitstemperatur einen Druck auf den Kohlenstoffblock 10 ausüben, wird dieser aufgefangen, indem die Lappen 16 entsprechend auseinander gespreizt werden. Die Kanten 18 dieser Lappen 16 sind bevorzugt abgerundet oder abgeschnitten.The carbon block 10, which is rectangular in cross section, contains the round iron bars 12 which run parallel in the longitudinal direction in correspondingly shaped grooves 14 which are partially open at the bottom. Each tab 16 of the carbon block 10 comprises the iron bars 12 in a U-shape. If the iron bars 12 exert pressure on the carbon block 10 at working temperature, this is absorbed by the Tabs 16 are spread apart accordingly. The edges 18 of these tabs 16 are preferably rounded or cut off.

Nach dem vollständigen Absenken liegt der in die Elektrolysewanne eingesetzte Kohlenstoffblock 10 entlang der Mantellinien 20 der Eisenbarren 12 auf der nicht gezeichneten Isolationsschicht. Dadurch werden die Eisenbarren 12 in ihrem oberen Bereich flächenförmig auf den entsprechenden Bereich der Nuten 14 gedrückt, der Uebergangswiderstand vom Kohlenstoff zum Eisen ist dadurch minimal. Der elektrische Gleichstrom kann auf direktem Weg von der Deckfläche des Kohlenstoffblocks 10 und mit geringem Uebergangswiderstand in Richtung der Pfeile zum Eisenbarren 12 fliessen.After complete lowering, the carbon block 10 inserted into the electrolysis trough lies along the surface lines 20 of the iron bars 12 on the insulation layer (not shown). As a result, the iron bars 12 are pressed flatly in their upper area onto the corresponding area of the grooves 14, the transition resistance from carbon to iron is minimal as a result. The direct electric current can flow directly from the top surface of the carbon block 10 and with a low transition resistance in the direction of the arrows to the iron bar 12.

Die wesentlichen Vorteile der Erfindung können wie folgt zusammengefasst werden:

  • - Die Eisenbarren müssen nicht mehr eingegossen, eingeklebt oder eingestampft werden, sondern können einfach durch Barrenfenster in eine entsprechende, nach unten offene Nut des Kohlenstoffblocks eingeschoben werden. Das bedeutet Ersparnisse in bezug auf Energie, Material, Zeitaufwand, Equipment und Werkstatt.
  • - Der Kohlenstoffblock ist nicht mehr den Gefahren des Eingiessens ausgesetzt, die beim Transport, Vorwärmen, Eingiessen und Manipulieren auftreten.
  • - Der Spannungsabfall des Elektrolyseprozesses im kathodischen Teil kann bis zu 0,1 Volt vermindert werden.
The main advantages of the invention can be summarized as follows:
  • - The iron bars no longer have to be poured in, glued in or stamped in, but can simply be inserted through bar windows into a corresponding groove of the carbon block which is open at the bottom. That means savings in terms of energy, material, time, equipment and workshop.
  • - The carbon block is no longer exposed to the dangers of pouring that occur during transport, preheating, pouring and manipulation.
  • - The voltage drop of the electrolysis process in the cathodic part can be reduced by up to 0.1 volt.

Claims (10)

1. Elektrolysewanne zur Herstellung von Aluminium mittels Schmelzflusselektrolyse, bestehend aus einer äusseren Stahlwanne, einer wärmedämmenden Isolationsschicht und einer elektrisch leitenden, gegen das schmelzflüssige Material beständigen Innenauskleidung aus in Querrichtung verlaufenden Kohlenstoffblöcken mit eingesetzten, beidseitig aus deren Stirnseiten herausragenden massiven Eisenbarren,
dadurch gekennzeichnet, dass - in jedem Kohlenstoffblock (10) in dessen Längsrichtung über mindestens 20% der Länge, ausgehend von beiden Stirnseiten, in Arbeitsposition nach unten offene Nuten (14) ausgespart sind, die in bezug auf den Querschnitt bei 500-850°C exakt dem Querschnitt der auf dieselbe Temperatur erwärmten Eisenbarren (12) entsprechen, - die in die Nuten (14) eingesetzten sich über mindestens 20% der Länge des Kohlenstoffblocks, ausgehend von den Stirnseiten, erstreckenden Eisenbarren (12) während des Elektrolyseprozesses entlang der ganzen unteren Seitenfläche bzw. Mantellinie (20) aus dem Kohlenstoffblock (10) herausragen und - ein Teil des Gewichts der Kohlenstoffblöcke (1G) ungefähr gleichmässig auf allen Eisenbarren (12) abgestützt ist. 1.electrolysis tub for the production of aluminum by means of melt flow electrolysis, consisting of an outer steel tub, a heat-insulating layer and an electrically conductive inner lining resistant to the molten material made of transverse carbon blocks with solid iron bars protruding on both sides from their front sides,
characterized in that - In each carbon block (10) in the longitudinal direction over at least 20% of the length, starting from both end faces, in the working position down open grooves (14) are recessed, which with respect to the cross section at 500-850 ° C exactly the cross section of the correspond to iron bars (12) heated to the same temperature, - The inserted into the grooves (14) over at least 20% of the length of the carbon block, starting from the end faces, extending iron bars (12) during the electrolysis process along the entire lower side surface or surface line (20) protrude from the carbon block (10) and - Part of the weight of the carbon blocks (1G) is supported approximately evenly on all iron bars (12). 2. Elektrolysewanne nach Anspruch 1, dadurch gekennzeichnet, dass der Querschnitt der Nuten (14) in den auf etwa 700°C erwärmten Kohlenstoffblöcken (10) exakt dem Querschnitt der auf dieselbe Temperatur erwärmten Eisenbarren (12) entspricht.2. Electrolysis bath according to claim 1, characterized in that the cross section of the grooves (14) in the carbon blocks (10) heated to approximately 700 ° C corresponds exactly to the cross section of the iron bars (12) heated to the same temperature. 3. Elektrolysewanne nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Eisenbarren (12) während des Elektrolyseprozesses 0,5-1,5 cm aus der Bodenfläche der Kohlenstoffblöcke (10) herausragen.3. Electrolysis bath according to claim 1 or 2, characterized in that the iron bars (12) protrude 0.5-1.5 cm from the bottom surface of the carbon blocks (10) during the electrolysis process. 4. Elektrolysewanne nach mindestens einem der Ansprüche 1-3, dadurch gekennzeichnet, dass die Nuten (14) in den Kohlenstoffblöcken (10) und die entsprechenden Eisenbarren (12) mindestens in ihrem - in bezug auf die Arbeitsposition - oberen Bereich abgerundete Querschnitte haben.4. Electrolysis bath according to at least one of claims 1-3, characterized in that the grooves (14) in the carbon blocks (10) and the corresponding iron bars (12) have rounded cross-sections at least in their - in relation to the working position - upper region. 5. Elektrolysewanne nach Anspruch 4, dadurch gekennzeichnet, dass der Querschnitt von Nuten (14) und Eisenbarren (12) kreisrund ist.5. Electrolysis tub according to claim 4, characterized in that the cross section of grooves (14) and iron bars (12) is circular. 6. Elektrolysewanne nach mindestens einem der Ansprüche 1-5, dadurch gekennzeichnet, dass die Barrenfenster in der Stahlwanne die gleiche geometrische Form wie der Querschnitt der Eisenbarren (12) haben.6. Electrolysis tub according to at least one of claims 1-5, characterized in that the bar windows in the steel tub have the same geometric shape as the cross section of the iron bars (12). 7. Elektrolysewanne nach Anspruch 6, dadurch gekennzeichnet, dass die Barrenfenster nur wenig, vorzugsweise 0,5-2 cm grösser sind als die linearen Dimensionen der Eisenbarrenquerschnitte.7. Electrolysis tub according to claim 6, characterized in that the bar windows are only a little, preferably 0.5-2 cm larger than the linear dimensions of the iron bar cross sections. 8. Verfahren zum Einsetzen der Eisenbarren in einer Elektrolysewanne nach mindestens einem der Ansprüche 1-7, dadurch gekennzeichnet, dass die Eisenbarren (12) durch Barrenfenster in der Stahlwanne bei Umgebungstemperatur in den Innenraum der Elektrolysewanne geschoben werden.8. The method for inserting the iron bars in an electrolysis tank according to at least one of claims 1-7, characterized in that the iron bars (12) are pushed through bar windows in the steel tank at ambient temperature into the interior of the electrolysis tank. 9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass bei im unteren Teil rechteckigen oder sich nacn oben verjüngenden Eisenbarren (12) die Kohlenstoffblöcke (10) auf die entsprechend den Nuten (14) angeordneten Eisenbarren (12) abgesenkt werden.9. The method according to claim 8, characterized in that in the lower part of rectangular or nacn tapering iron bars (12), the carbon blocks (10) are lowered onto the iron bars (12) arranged corresponding to the grooves (14). 10. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass die Kohlenstoffblöcke (10) vorerst bis wenig, vorzugsweise etwa 0,5-2,5 cm, über die Isolationsschicht abgesenkt, dann die Eisenbarren (12) in die Nuten (14) geschoben, und schliesslich die Kohlenstoffblöcke (10) vollständig abgesenkt werden.10. The method according to claim 8, characterized in that the carbon blocks (10) are initially lowered to a little, preferably about 0.5-2.5 cm, over the insulation layer, then the iron bars (12) are pushed into the grooves (14), and finally the carbon blocks (10) are completely lowered.
EP82810344A 1981-08-31 1982-08-18 Electrolytic pot for the production of aluminium by electrolysis in the dry way, and method of inserting the iron bars Expired EP0073735B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82810344T ATE16202T1 (en) 1981-08-31 1982-08-18 ELECTROLYSIS TANK FOR THE PRODUCTION OF ALUMINUM BY MEANS OF MOLTEN FLOW ELECTROLYSIS AND METHOD OF INSERTING THE IRON BAR.

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CH5567/81A CH657383A5 (en) 1981-08-31 1981-08-31 ELECTROLYSIS PAN FOR PRODUCING ALUMINUM BY MELTFLOW ELECTROLYSIS AND METHOD FOR INSERTING THE IRON BAR.
CH5567/81 1981-08-31
DE3135083A DE3135083C1 (en) 1981-08-31 1981-09-04 Electrolytic pot for producing aluminium by means of molten-salt electrolysis and method for employing the iron bars

Publications (3)

Publication Number Publication Date
EP0073735A2 true EP0073735A2 (en) 1983-03-09
EP0073735A3 EP0073735A3 (en) 1983-04-20
EP0073735B1 EP0073735B1 (en) 1985-10-23

Family

ID=25697998

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82810344A Expired EP0073735B1 (en) 1981-08-31 1982-08-18 Electrolytic pot for the production of aluminium by electrolysis in the dry way, and method of inserting the iron bars

Country Status (7)

Country Link
EP (1) EP0073735B1 (en)
JP (1) JPS5845390A (en)
AU (1) AU557296B2 (en)
CA (1) CA1190517A (en)
CH (1) CH657383A5 (en)
DE (1) DE3135083C1 (en)
ZA (1) ZA826026B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO157462C (en) * 1985-10-24 1988-03-23 Hydro Aluminium As LAMINATED CARBON CATHOD FOR CELLS-MELT-ELECTROLYTIC ALUMINUM PREPARATION.
GB2542150A (en) * 2015-09-09 2017-03-15 Dubai Aluminium Pjsc Cathode assembly for electrolytic cell suitable for the Hall-Héroult process
DE102016210693A1 (en) * 2016-06-15 2017-12-21 Sgl Cfl Ce Gmbh Cathode block having a novel groove geometry

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3851377A (en) * 1973-03-27 1974-12-03 D Dumas Sealing of metal bars in carbonized blocks
USB430385I5 (en) * 1974-01-03 1975-01-28
FR2318244A1 (en) * 1975-07-17 1977-02-11 Savoie Electrodes Refactaires PROCESS FOR JOINING METAL BARS WITH CARBON BLOCKS
US4076610A (en) * 1975-07-10 1978-02-28 Elettrocarbonium S.P.A. Cathode in cells for producing aluminium by electrolysis of smelted salts thereof

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2105247C3 (en) * 1971-02-04 1980-06-12 Schweizerische Aluminium Ag, Zuerich (Schweiz) Furnace for the fused aluminum electrolysis

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3851377A (en) * 1973-03-27 1974-12-03 D Dumas Sealing of metal bars in carbonized blocks
USB430385I5 (en) * 1974-01-03 1975-01-28
US4076610A (en) * 1975-07-10 1978-02-28 Elettrocarbonium S.P.A. Cathode in cells for producing aluminium by electrolysis of smelted salts thereof
FR2318244A1 (en) * 1975-07-17 1977-02-11 Savoie Electrodes Refactaires PROCESS FOR JOINING METAL BARS WITH CARBON BLOCKS

Also Published As

Publication number Publication date
JPS5845390A (en) 1983-03-16
DE3135083C1 (en) 1983-03-10
AU8748082A (en) 1983-03-10
CH657383A5 (en) 1986-08-29
CA1190517A (en) 1985-07-16
EP0073735B1 (en) 1985-10-23
AU557296B2 (en) 1986-12-18
EP0073735A3 (en) 1983-04-20
ZA826026B (en) 1983-07-27

Similar Documents

Publication Publication Date Title
DE69532052T2 (en) Horizontal cathode surface drained with recessed grooves for aluminum electrical extraction
DE60019724T2 (en) CATHODE COLLECTOR WITH SPACER FOR IMPROVED HEAT BALANCE
EP0073735B1 (en) Electrolytic pot for the production of aluminium by electrolysis in the dry way, and method of inserting the iron bars
EP0052577B1 (en) Anchorage for a cathode bar
EP0117842A1 (en) Fixation of anode studs or spades in a carbon anode
DE1075321B (en) Continuous electrodes for melt flow electrolysis
EP3546620B1 (en) Cathode assembly having a cathode block having a slot with varying depth and a securing system
DE1202988B (en) Aluminum electrolytic furnace
DE861750C (en) Electrolytic cell
DE3514963A1 (en) Anode and method for the production thereof
DE2731908C2 (en) Method and apparatus for producing aluminum
DE1558726C3 (en)
DE898817C (en) Furnace for direct fused aluminum electrolysis
EP0099331A1 (en) Aluminium electrolysis cell pot
DE3044676C2 (en) Anchoring for a cathode bar
EP0197003A1 (en) Electrolysis vat for the production of aluminium
DE2833381A1 (en) Electrolysis cell for winning aluminium - where carbon cathode hearth is connected to bus=bars via spaced graphite pegs increasing the efficiency of aluminium prodn.
DE2052527A1 (en) Welded joint
DE1148755B (en) Cell for fused salt electrolysis and process for the production of aluminum
DE1758306A1 (en) Electrolysis cell for the production of aluminum
DE809109C (en) Tub for refining aluminum
DE10164013C1 (en) Longitudinal graphitization of cathode blocks for electrolytic production of aluminum comprises arranging blocks with gap between their ends, conductive moldings being placed between blocks
AT204796B (en) Furnace for fused flux electrolysis and process for the production of metals, in particular aluminum, by fused flux electrolysis.
CH663624A5 (en) Cathode element of a cathode vessel for producing aluminium
DE10164008C1 (en) Graphitized cathode block, used for producing aluminum by electrolytically reducing aluminum oxide in a bath of molten cryolite, is composed of two parts and has a V-shaped profile of its electrical resistance over its length

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Designated state(s): AT CH DE FR GB IT LI NL SE

AK Designated contracting states

Designated state(s): AT CH DE FR GB IT LI NL SE

17P Request for examination filed

Effective date: 19830511

ITF It: translation for a ep patent filed

Owner name: DE DOMINICIS & MAYER S.R.L.

RBV Designated contracting states (corrected)

Designated state(s): AT CH FR GB IT LI NL SE

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): AT CH FR GB IT LI NL SE

REF Corresponds to:

Ref document number: 16202

Country of ref document: AT

Date of ref document: 19851115

Kind code of ref document: T

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19870831

Year of fee payment: 6

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19880818

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19880819

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Effective date: 19880831

Ref country code: CH

Effective date: 19880831

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19890301

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

GBPC Gb: european patent ceased through non-payment of renewal fee
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19910812

Year of fee payment: 10

ITTA It: last paid annual fee
REG Reference to a national code

Ref country code: FR

Ref legal event code: TP

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19920818

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19920828

Year of fee payment: 11

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19940429

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

EUG Se: european patent has lapsed

Ref document number: 82810344.0

Effective date: 19890510