Nothing Special   »   [go: up one dir, main page]

EP0034391B1 - Use of a lead alloy for the anodes in the electrolytic production of zinc - Google Patents

Use of a lead alloy for the anodes in the electrolytic production of zinc Download PDF

Info

Publication number
EP0034391B1
EP0034391B1 EP81200163A EP81200163A EP0034391B1 EP 0034391 B1 EP0034391 B1 EP 0034391B1 EP 81200163 A EP81200163 A EP 81200163A EP 81200163 A EP81200163 A EP 81200163A EP 0034391 B1 EP0034391 B1 EP 0034391B1
Authority
EP
European Patent Office
Prior art keywords
anodes
zinc
weight
lead alloy
lead
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
Application number
EP81200163A
Other languages
German (de)
French (fr)
Other versions
EP0034391A1 (en
Inventor
Adolf Dr.-Ing. Von Röpenack
Günter Ing. grad. Stock
Ulrich Dr.-Ing. Heubner
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.)
Ruhr Zink GmbH
Original Assignee
Ruhr Zink GmbH
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 Ruhr Zink GmbH filed Critical Ruhr Zink GmbH
Publication of EP0034391A1 publication Critical patent/EP0034391A1/en
Application granted granted Critical
Publication of EP0034391B1 publication Critical patent/EP0034391B1/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C11/00Alloys based on lead
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • C25C1/16Electrolytic production, recovery or refining of metals by electrolysis of solutions of zinc, cadmium or mercury
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/02Electrodes; Connections thereof

Definitions

  • the wet metallurgical extraction of zinc usually takes place according to the process principle of zinc blende roasting, leaching of the roasted material, lye cleaning, electrolytic deposition of zinc and remelting agent. of the zinc previously drawn from the cathodes. Electrolytic deposition takes place practically exclusively from sulfuric acid solutions with the help of aluminum cathodes and lead anodes.
  • Anode materials are primarily ternary lead alloys with mostly silver contents that are between 0.5 and 1.0% by weight.
  • the third alloy component studies are available on thallium, tellurium, selenium, bismuth, calcium, gold, mercury, strontium, barium, arsenic, tin and cobalt (The Journal of Ap- .plied Chemistry of the USSR - english translation - Vol. 24 (1951) pp. 1429 ff) as well as magnesium and silicon (The Journal of Applied Chemistry of the USSR - english translation - Vol. 26 (1953) pp. 847 ff).
  • the object of the invention is to provide an alloy for anodes in the electrolytic extraction of zinc from acidic solutions which do not have the disadvantages of the known alloys, have advantageous electrical and mechanical properties and can be produced as inexpensively as possible.
  • the solution to the problem lies in the use of a lead alloy consisting of 0.05 to 0.25% by weight of strontium and / or 0.05 to 0.1% by weight of calcium and 0.1 to 0.5% by weight of silver , Remaining lead for anodes in the electrolytic extraction of zinc from acidic solutions.
  • strontium-containing alloys those in which the strontium content is 0.05 to 0.1% by weight are preferably used.
  • the anodes made from the aforementioned alloys have considerable hardness and high elasticity. They are dimensionally stable, so that they can be produced in a smaller thickness than conventional anodes. This saves alloy material in general and silver in particular. Due to the low weight of the anodes, the connection elements, in particular the support rods, can also be constructed more easily.
  • the high dimensional stability of the anodes allows the electrode gap to be reduced, so that a reduction in energy consumption is achieved.
  • Alloys containing calcium or strontium are expediently used for reasons of simpler production. With regard to their properties, however, those that have both alloy components are also equivalent.
  • the anodes can be produced by rolling or casting.
  • the possibility of casting is advantageous insofar as the anodes are immediately given their final dimensions and - if desired - passage openings for the electrolyte can already be provided during the casting.
  • the strength of the metal alloy is so high that even in the manufacture of anodes with through openings, a greater thickness - for reasons of stability, for example - is not necessary.
  • the corrosion resistance of the anodes is so high that there is practically no removal even after months of operation. This is particularly surprising because there was a fear that a reduction in the silver content in the alloy would be associated with an increase in corrosion.

Landscapes

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

Description

Die naßmetallurgische Gewinnung von Zink erfolgt üblicherweise nach dem Verfahrensprinzip Zinkblenderöstung, Laugung des Röstgutes, Laugenreinigung, elektrolytische Abscheidung von Zink und Umschmelzer. des zuvor von den Kathoden abgezogenen Zinks. Die elektrolytische Abscheidung geschieht dabei praktisch ausschließlich aus schwefelsauren Lösungen mit Hilfe von Aluminiumkathoden und Bleianoden.The wet metallurgical extraction of zinc usually takes place according to the process principle of zinc blende roasting, leaching of the roasted material, lye cleaning, electrolytic deposition of zinc and remelting agent. of the zinc previously drawn from the cathodes. Electrolytic deposition takes place practically exclusively from sulfuric acid solutions with the help of aluminum cathodes and lead anodes.

Anodenmaterialien sind vorwiegend ternäre Blei-Legierungen mit meist Silber-Gehalten, die zwischen 0,5 bis 1,0 Gew.% liegen. Hinsichtlich der dritten Legierungskomponente liegen Untersuchungen über Thallium, Tellur, Selen, Wismut, Calzium, Gold, Quecksilber, Strontium, Barium, Arsen, Zinn und Kobalt vor (The Journal of Ap- .plied Chemistry of the UdSSR - english translation - Vol. 24 (1951) S. 1429 ff) sowie Magnesium und Silizium (The Journal of Applied Chemistry of the UdSSR - english translation - Vol. 26 (1953) S. 847 ff).Anode materials are primarily ternary lead alloys with mostly silver contents that are between 0.5 and 1.0% by weight. Regarding the third alloy component, studies are available on thallium, tellurium, selenium, bismuth, calcium, gold, mercury, strontium, barium, arsenic, tin and cobalt (The Journal of Ap- .plied Chemistry of the USSR - english translation - Vol. 24 (1951) pp. 1429 ff) as well as magnesium and silicon (The Journal of Applied Chemistry of the USSR - english translation - Vol. 26 (1953) pp. 847 ff).

Dabei zeigt sich, daß Anoden aus verschiedenen Legierungen während des Elektrolysebetriebes einen beträchtlichen Gewichtsverlust erleiden, der - abgesehen vom schnellen Verbrauch des Anodenmaterials - auch insofern nachteilig ist, als sich beträchtliche Schlammengen bilden können oder aber das kathodisch abgeschiedene Zink stark verunreinigt wird. Eine zusätzliche Problematik ergibt sich aus dem Umstand, daß verschiedene Legierungen nicht die erforderliche mechanische Festigkeit aufweisen oder während des Gebrauchs die anfänglich vorhandene Festigkeit verlieren. Es kann dann zu Verwerfungen und als Folge hiervon zu Kurzschlüssen und Brennern kommen.It is shown that anodes made of various alloys suffer considerable weight loss during electrolysis operation, which - apart from the rapid consumption of the anode material - is also disadvantageous in that considerable amounts of sludge can form or the cathodically deposited zinc is heavily contaminated. An additional problem arises from the fact that different alloys do not have the required mechanical strength or lose the initially existing strength during use. This can lead to faults and, as a result, short circuits and burners.

Wie insbesondere auch die Ausführungen in « Blei und Bleilegierungen von W. Hofmann, Springer-Verlag 1962, S. 285 ff zeigen, sind die Einflüsse der von Blei verschiedenen Legierungskomponenten vielfältig, zum Teil widersprüchlich und praktisch nicht vorhersehbar. Schließlich sind auch die mit der Herstellung der Legierung verbundenen Kosten von beträchtlicher Bedeutung, insbesondere wenn man berücksichtigt, daß sich in der Bäderhalle moderner Zinkelektrolysen Bleilegierungsmengen in der Größenordnung von 1.000 und mehr befinden.As especially the explanations in "Lead and lead alloys by W. Hofmann, Springer-Verlag 1962, p. 285 ff. Show, the influences of the alloy components other than lead are diverse, partly contradictory and practically unpredictable. Finally, the costs associated with the production of the alloy are also of considerable importance, especially if one takes into account that there are quantities of lead alloys in the order of 1,000 and more in the bath hall of modern zinc electrolysis.

Aufgabe der Erfindung ist es, eine Legierung für Anoden bei der elektrolyt:schen Gewinnung von Zink aus sauren Lösungen bereitzustellen, die die Nachteile der bekannten Legierungen nicht aufweisen, vorteilhafte elektrische und mechanische Eigenschaften besitzen und möglichst kostengünstig herstellbar sind.The object of the invention is to provide an alloy for anodes in the electrolytic extraction of zinc from acidic solutions which do not have the disadvantages of the known alloys, have advantageous electrical and mechanical properties and can be produced as inexpensively as possible.

Die Lösung der Aufgabe liegt in der Verwendung einer Blei-Legierung, bestehend aus 0.05 bis 0,25 Gew.% Strontium und/oder 0,05 bis 0,1 Gew.% Calzium sowie 0,1 bis 0,5 Gew.% Silber, Rest Blei für Anoden bei der elektrolytischen Gewinnung von Zink aus sauren Lösungen.The solution to the problem lies in the use of a lead alloy consisting of 0.05 to 0.25% by weight of strontium and / or 0.05 to 0.1% by weight of calcium and 0.1 to 0.5% by weight of silver , Remaining lead for anodes in the electrolytic extraction of zinc from acidic solutions.

Sofern strontiumhaltige Legierungen vorgesehen sind, kommen vorzugsweise solche zur Anwendung, in denen der Strontium-Gehalt 0,05 bis 0,1 Gew.% beträgt.If strontium-containing alloys are provided, those in which the strontium content is 0.05 to 0.1% by weight are preferably used.

Die aus den vorgenannten Legierungen hergestellten Anoden besitzen eine beträchtliche Härte und eine hohe Elastizität. Sie sind formbeständig, so daß sie - verglichen mit üblichen Anoden - in geringerer Dicke hergestellt werden können. Hiermit verbunden ist eine Einsparung an Legierungsmaterial generell und insbesondere an Silber möglich. Infolge des geringen Gewichtes der Anoden können auch die Anschlußelemente, insbesondere die Tragestangen, leichter konstruiert werden.The anodes made from the aforementioned alloys have considerable hardness and high elasticity. They are dimensionally stable, so that they can be produced in a smaller thickness than conventional anodes. This saves alloy material in general and silver in particular. Due to the low weight of the anodes, the connection elements, in particular the support rods, can also be constructed more easily.

Die hohe Formbeständigkeit der Anoden läßt es zu, daß der Elektrodenabstand verkleinert werden kann, so daß eine Verringerung des Energieverbrauchs erzielt wird.The high dimensional stability of the anodes allows the electrode gap to be reduced, so that a reduction in energy consumption is achieved.

Aus Gründen der einfacheren Herstellung werden zweckmäßigerweise Legierungen eingesetzt, die Calzium oder Strontium enthalten. Hinsichtlich ihrer Eigenschaften sind jedoch auch solche, die beide Legierungsbestandteile aufweisen, gleichwertig.Alloys containing calcium or strontium are expediently used for reasons of simpler production. With regard to their properties, however, those that have both alloy components are also equivalent.

Die Herstellung der Anoden kann durch Walzen oder Gießen erfolgen. Insbesondere die Möglichkeit des Gießens ist insofern vorteilhaft, als die Anoden unmittelbar ihre endgültigen Abmessungen erhalten und - sofern erwünscht - bereits beim Guß Durchtrittsöffnungen für den Elektrolyt vorgesehen werden können. Die Festigkeit der Metallegierung ist so hoch, daß auch bei der Herstellung von Anoden mit Durchtrittsöffnungen eine größere Dicke - etwa aus Stabilitätsgründen - nicht erforderlich ist.The anodes can be produced by rolling or casting. In particular, the possibility of casting is advantageous insofar as the anodes are immediately given their final dimensions and - if desired - passage openings for the electrolyte can already be provided during the casting. The strength of the metal alloy is so high that even in the manufacture of anodes with through openings, a greater thickness - for reasons of stability, for example - is not necessary.

Bei der Herstellung von Gußanoden, die generell eine höhere Härte als Walzanoden aufweisen, empfiehlt sich eine langsame Abkühlung, weil hierdurch im Vergleich zur schnellen Abkühlung eine zusätzliche Erhöhung der Härte und der Korrosionsbeständigkeit erzielt wird.In the production of cast anodes, which generally have a higher hardness than rolled anodes, slow cooling is recommended, because in this way an additional increase in hardness and corrosion resistance is achieved compared to rapid cooling.

Die Korrosionsbeständigkeit der Anoden ist so hoch, daß ein Abtrag selbst nach monatelangem Betrieb praktisch nicht vorhanden ist. Dies ist insbesondere deswegen überraschend als zu befürchten war, daß eine Reduktion des Silber-Gehaltes in der Legierung mit einer Vergrößerung der Korrosion verbunden sein würde.The corrosion resistance of the anodes is so high that there is practically no removal even after months of operation. This is particularly surprising because there was a fear that a reduction in the silver content in the alloy would be associated with an increase in corrosion.

Die erhaltenen Anoden werden unter den üblicherweise angewendeten Elektrolysebedingungen eingesetzt, d. h. beispielsweise

  • bei einer Stromdichte von 160 bis 630 A/m2 einer Temperatur von 30 bis 46 °C und
  • bei einem Schwefelsäuregehalt des Elektrolyten von 165 bis 220 g/1 und
  • einem Zinkgehalt des Elektrolyten von 40 bis 70 g/I.
The anodes obtained are used under the usual electrolysis conditions, ie for example
  • at a current density of 160 to 630 A / m 2 a temperature of 30 to 46 ° C and
  • at a sulfuric acid content of the electrolyte of 165 to 220 g / 1 and
  • a zinc content of the electrolyte of 40 to 70 g / l.

Claims (2)

1. The use of a lead alloy consisting of 0.05 to 0.25 % by weight of strontium and/or 0.05 to 0.1 % by weight of calcium as well as 0.1 to 0.5 % by weight of silver, balance lead, for anodes for use in the electrolytic recovery of zinc from acid solutions.
2. The use according to claim 1, wherein the strontium content amounts to 0.05 to 0.1 % by weight.
EP81200163A 1980-02-15 1981-02-11 Use of a lead alloy for the anodes in the electrolytic production of zinc Expired EP0034391B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19803005674 DE3005674A1 (en) 1980-02-15 1980-02-15 USE OF A LEAD ALLOY FOR ANODES IN THE ELECTROLYTIC EXTRACTION OF ZINC
DE3005674 1980-02-15

Publications (2)

Publication Number Publication Date
EP0034391A1 EP0034391A1 (en) 1981-08-26
EP0034391B1 true EP0034391B1 (en) 1983-08-24

Family

ID=6094697

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81200163A Expired EP0034391B1 (en) 1980-02-15 1981-02-11 Use of a lead alloy for the anodes in the electrolytic production of zinc

Country Status (8)

Country Link
US (1) US4364807A (en)
EP (1) EP0034391B1 (en)
JP (1) JPS56127743A (en)
AU (1) AU538729B2 (en)
DE (2) DE3005674A1 (en)
ES (1) ES8704552A1 (en)
FI (1) FI65821C (en)
NO (1) NO153976C (en)

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272339A (en) * 1980-03-10 1981-06-09 Knight Bill J Process for electrowinning of metals
IT1133952B (en) * 1980-10-20 1986-07-24 Samim Spa UNATTACKABLE ANODE IN ALLIGATED LEAD
CA1232227A (en) * 1982-02-18 1988-02-02 Christopher Vance Manufacturing electrode by immersing substrate in aluminium halide and other metal solution and electroplating
JPS5959891A (en) * 1982-09-28 1984-04-05 Akita Seiren Kk Anode for electrowinning metal
US4439288A (en) * 1983-07-11 1984-03-27 Exxon Research & Engineering Company Process for reducing Zn consumption in zinc electrolyte purification
IT1178784B (en) * 1984-12-21 1987-09-16 Samim Soc Azionaria Minero Met COMPOSITE MATERIAL
FR2691649B1 (en) * 1992-05-29 1995-06-02 Extramet Sa Method for decontaminating soil polluted by metals.
JPH0652737U (en) * 1992-12-26 1994-07-19 合資会社榊原 Insulation for canned food
US5648286A (en) * 1996-09-03 1997-07-15 Advanced Micro Devices, Inc. Method of making asymmetrical transistor with lightly doped drain region, heavily doped source and drain regions, and ultra-heavily doped source region
US6139705A (en) * 1998-05-06 2000-10-31 Eltech Systems Corporation Lead electrode
JP3499216B2 (en) * 1999-01-13 2004-02-23 アールエスアール テクノロジーズ, インコーポレイテッド Electrowinning anode for rapid production of protective oxide coatings
JP5048981B2 (en) * 2006-08-29 2012-10-17 アシスト株式会社 Mist sauna equipment
US7458902B2 (en) * 2007-03-14 2008-12-02 Eaton Corporation Changeable golf grip
BG110844A (en) * 2011-02-04 2012-10-31 "Кцм" Ад A method and a device for electroextraction of zinc out of sulphate solutions
CN103042031B (en) * 2011-10-12 2016-06-08 云南大泽电极科技有限公司 The casting-rolling production method of metal sheet material
BR112015003067A2 (en) 2012-08-24 2017-07-04 Novartis Ag nep inhibitors to treat diseases characterized by atrial enlargement or remodeling
CN106319565A (en) * 2016-09-21 2017-01-11 东莞市联洲知识产权运营管理有限公司 Method for preparing zinc electrodeposit under ammoniac system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272339A (en) * 1980-03-10 1981-06-09 Knight Bill J Process for electrowinning of metals

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Czoka et Papahadjoupoulos Ann. Rev. BioPhys. BioEng. 1980 9:467-508, pp 467,485,486 (2ex.) *
D Dreamer et al Biochimica et Biophysica Acta 443 (1976) pp 629-634 *
H Kremer et al Biochemistry vol. 16 no.17 1977 *
Pagano et Weinstein Ann.Rev. BioPhys. BioEng. 1978 7:435-68 *

Also Published As

Publication number Publication date
FI65821C (en) 1984-07-10
JPS56127743A (en) 1981-10-06
DE3160775D1 (en) 1983-09-29
NO810416L (en) 1981-08-17
AU6728681A (en) 1981-08-20
ES499435A0 (en) 1987-06-01
AU538729B2 (en) 1984-08-23
DE3005674A1 (en) 1981-08-20
JPS6323274B2 (en) 1988-05-16
FI810395L (en) 1981-08-16
US4364807A (en) 1982-12-21
EP0034391A1 (en) 1981-08-26
NO153976C (en) 1986-06-25
NO153976B (en) 1986-03-17
FI65821B (en) 1984-03-30
ES8704552A1 (en) 1987-06-01

Similar Documents

Publication Publication Date Title
EP0034391B1 (en) Use of a lead alloy for the anodes in the electrolytic production of zinc
DE2737928C3 (en) Process for recovering metal content from copper refining sludge
DE1094245B (en) Lead dioxide electrode for use in electrochemical processes
DE69904237T2 (en) Electro-extraction anodes with a fast-forming oxide protective layer
DE4318168C2 (en) Process for the direct electrochemical refining of copper waste
DE489869C (en) Device for the electrolytic refining of aluminum
DE2352704C2 (en) Weldable, oxidation-resistant cobalt alloy
EP0435382A1 (en) Electrolytic process for treating waste pickling solutions or product streams containing metallic ions
DE69314483T2 (en) Process for the continuous electrochemical refining of lead
DE3781756T2 (en) FLUID BED ELECTROLYSIS CELL.
WO1982001899A1 (en) Cathode for a melted electrolyte cell for the preparation of aluminum
DE1483361A1 (en) Method of manufacturing a superconducting wire
DE2232903A1 (en) TITANIUM ELECTRODES FOR COPPER REFINING
DE3821237C2 (en)
DE3443338C2 (en) Cathode for the production of electrolyte manganese dioxide
DE2027575C3 (en) Use of a lead alloy for anodes in acidic galvanic chrome-plating baths
DE852845C (en) Process for the decomposition of alkali amalgams
DE189875C (en)
DE1234397B (en) Use of gold and / or silver alloys as a material for electrical contacts and processes for making contacts
DE2545407C3 (en) Process for applying oxidic separating layers to facilitate removal of cathodically deposited zinc
CH496096A (en) Process for the production of steels with improved machinability
DE1907523C3 (en) Process for the extractive electrolysis of zinc from its sulfuric acid solutions
AT228521B (en) Magnetic material and process for its manufacture
AT40836B (en) Process for the regeneration of the electrolyte in the electrolytic copper production from old bronzes.
DE898468C (en) Process for the production of electrical resistors

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

AK Designated contracting states

Designated state(s): BE DE FR IT NL

17P Request for examination filed

Effective date: 19811031

ITF It: translation for a ep patent filed
GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): BE DE FR IT NL

REF Corresponds to:

Ref document number: 3160775

Country of ref document: DE

Date of ref document: 19830929

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: FR

Payment date: 19891221

Year of fee payment: 10

ITTA It: last paid annual fee
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19900228

Year of fee payment: 10

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

Ref country code: BE

Payment date: 19900308

Year of fee payment: 10

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

Ref country code: DE

Payment date: 19900313

Year of fee payment: 10

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

Ref country code: BE

Effective date: 19910228

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

Ref country code: NL

Effective date: 19910901

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19911031

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

Ref country code: DE

Effective date: 19911101

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST