[go: up one dir, main page]

WO1988001532A1 - Filtre en ceramique pour le filtrage de metal en fusion - Google Patents

Filtre en ceramique pour le filtrage de metal en fusion Download PDF

Info

Publication number
WO1988001532A1
WO1988001532A1 PCT/CH1987/000100 CH8700100W WO8801532A1 WO 1988001532 A1 WO1988001532 A1 WO 1988001532A1 CH 8700100 W CH8700100 W CH 8700100W WO 8801532 A1 WO8801532 A1 WO 8801532A1
Authority
WO
WIPO (PCT)
Prior art keywords
filter
ceramic
coating
molten metal
ceramic filter
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.)
Ceased
Application number
PCT/CH1987/000100
Other languages
German (de)
English (en)
Inventor
Jerry W. Brockmeyer
James E. Dore
Leonard S. Aubrey
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.)
Rio Tinto 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 BR8707442A priority Critical patent/BR8707442A/pt
Publication of WO1988001532A1 publication Critical patent/WO1988001532A1/fr
Priority to NO881756A priority patent/NO881756L/no
Priority to DK2279/88A priority patent/DK227988D0/da
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
    • C04B41/5035—Silica
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/85—Coating or impregnation with inorganic materials
    • C04B41/87—Ceramics
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B21/00—Obtaining aluminium
    • C22B21/06—Obtaining aluminium refining
    • C22B21/066—Treatment of circulating aluminium, e.g. by filtration
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/02—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves
    • C22B9/023—By filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0471—Surface coating material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention relates to ceramic filters for the filtration of molten metal from a bonded or sintered ceramic body containing a multiplicity of flow paths for the flow through the molten metal.
  • molten metal contains penetrated solids which have a detrimental effect in the finished cast product. These penetrated solids appear as inclusions in the finished cast product after the molten metal has solidified and cause defects in the finished product.
  • the inclusions can come from various sources, for example from superficial oxide films and insoluble impurities such as carbides, borides and others.
  • Ceramic filters as described in US Pat. Nos. 3,893,917, 4,081,371 and 3,962,081, are particularly suitable for the filtration of molten metal. These ceramic foam filters with an open cell structure with a large number of interconnected cavities, which are surrounded by a network of ceramic in order to ensure winding paths through them, are particularly suitable.
  • Ceramic foam filters coated with US Pat. No. 4,302,502 were also known, in which a proportionally large activation layer is provided for the removal of specific impurities from the molten metal.
  • the object of the present invention is to avoid the disadvantage of the metal supernatant and, accordingly, to propose an improved ceramic filter for the filtration of molten metal which promotes the filtration of poorly flowable metal without building up an excessive metal supernatant.
  • Another object of the present invention is to provide an improved filter which avoids the need for excessive overheating in order to make the filter wettable.
  • this is done by means of a ceramic filter, characterized by a thin coating which extends completely through its expanses, made of an inorganic material which can be easily wetted by the molten metal and which has a thickness of 5 ⁇ up to 1 micron adheres to this ceramic body, and the coating is removed on contact by the molten metal.
  • the present invention accordingly describes a highly effective ceramic filter for the filtration of molten metal, which overcomes the problem of the poor flow behavior of metals, such as steel, and shows favorable wetting properties, without the excessive build-up of a metal protrusion and without the need for a strong one Overheating the metal.
  • the ceramic filter of the present invention comprises a bonded or sintered ceramic filter with a plurality of flow paths for the flow through the molten metal with a thin coating, bonded to the ceramic body and extending essentially over the entire extent of the inorganic material which is wetted by the molten metal. The coating is removed by the flowing molten metal.
  • the ceramic filter is preferably a ceramic foam filter with an open-cell foam structure and a multiplicity of interconnected cavities which are surrounded by a network of this ceramic.
  • the ceramic body preferably contains aluminum oxide as the ceramic material.
  • the preferred thickness of the coating is 10 to 100 ⁇ .
  • the coating is uniform in its layer thickness and contains, preferably for the filtration of steel, silicon dioxide.
  • the ideal situation a high filter efficiency, is achieved if the material of the base metal to be filtered does not properly wet the filter, but the inclusions that have to be removed are able to completely wet the filter material.
  • an aluminum oxide inclusion in steel completely wets a ceramic filter based on aluminum oxide, while steel only partially wets the filter.
  • the inclusions therefore have the tendency to leave the metal stream and adhere to the filter.
  • the base metal tends not to stay in contact with the filter or inclusions.
  • the base metal does not wet the filter and thus causes less attack on the filter material. This behavior represents the desirable situation as soon as the flow through the filter begins, ie when the filter is already cast on.
  • the ceramic body of the present invention is a bonded or sintered ceramic body with a large number of flow paths for the flow through the molten metal.
  • All known ceramic bodies can be used, e.g. extruded ceramic bodies, bodies made of sintered ceramic particles or preferably ceramic foam filters with an open cell structure, characterized by a large number of interconnected cavities, which are connected by a network of ceramic, and produce tortuous flow paths.
  • a particularly suitable ceramic foam filter is described in DE-OS 34 24 504.
  • a thin coating is applied to this ceramic body, this coating essentially extending through the entire body and the layer adhering to the body.
  • the coating is an inorganic material which is completely wetted by the molten metal and has a thickness of 5 ⁇ to 1 micron. In an expedient embodiment, the thickness of the coating is 10 to 100 ⁇ . This shows that the coating is very thin.
  • the coating is removed by contact with the molten metal, and after the start of the metal flow, the entire filter surface necessary for filter effectiveness is available.
  • the coating is preferably completely removed in less than 5 seconds, either by dissolution by the molten metal or by mechanical action of the molten metal on the ceramic network.
  • a coating is therefore preferred which is soluble or partially soluble in the molten metal.
  • a coating of less than 100 ⁇ is preferably used, although it is also possible.
  • coatings of up to 1 micron in particular if the mechanical action is used to remove the particular coating.
  • the coating should extend essentially through the entire ceramic body in a uniform layer thickness, although fluctuations in the layer thickness and uncoated sections are still tolerable. In order to promote wetting, however, the coating should extend over the entire network and should preferably be uniform.
  • the coating material should be a material that is not detrimental to the molten metal to be filtered or in the final cast product. Therefore, mechanical separation of the coating from the network is less desirable than solubility or partial solubility in the metal, since the mechanically separated coating parts can appear as inclusions in the final cast product. In addition, the coating material should not have any on the molten metal have a disadvantageous effect, which leads, for example, to reduced mechanical properties, increased grain size or undesirable second phases.
  • a colloidal silicon dioxide coating is used, particularly since it was found that this is particularly advantageous for steel filtration and that a suitable silicon dioxide coating can thus be achieved on the ceramic body.
  • the silicon dioxide coating in the amounts used has no adverse effects on the steel to be filtered. Silicon dioxide could have a disadvantageous effect at most in large quantities, which are not the subject of the invention.
  • the thin silicon dioxide coating according to the invention is also completely removed on contact with the molten steel.
  • an aqueous dispersion of a colloidal silicon dioxide is used, starting from a 0.5 to 10% concentrated colloidal silicon dioxide in water, preferably in a concentration of 1%.
  • Additives can of course be used in the aqueous dispersion, such as wetting agents, dispersants or organic materials which support the tendency to coat, etc.
  • the aforementioned dispersion is produced and the ceramic body is immersed in the dispersion in order to achieve a thin coating thereon, essentially through the entire ceramic body.
  • Excess material is removed, for example shaken off, the moist ceramic body is dried, for example after-fired at 93 to 149 ° C., preferably at 121 ° C., and at 982 to 1038 ° C. and preferably at 1000 ° C.
  • the temperature treatment should be high enough that the silicon dioxide does not hydrate again and adheres firmly to the ceramic body.
  • the drying and re-firing can take place in separate steps or continuously. It is not necessary to keep the temperature.
  • the material coated in this way was found to be particularly advanced for steel filtration.
  • silicon dioxide is an inorganic material that is easily wetted by the molten material and removed in contact with the molten metal.
  • Silicon dioxide is particularly preferred for steel filtration because it is extremely well wetted by steel and is easily detached from the molten metal.
  • suitable additional inorganic materials include, for example, an aqueous silicate dispersion, such as sodium silicate, and salts, such as sodium chloride or calcium chloride, the latter salts simply being dried on the network instead of being fired again. It is also possible to use oxides, such as those of calcium or magnesium, which can then be dried and burned as salts, for example as carbonates.
  • Metals such as nickel, iron and chromium can be used as organometallic solutions or dispersions for coating, followed by a drying process and a heat treatment to convert them to metal. Given the very small amount that is used for the coating, these metals are not troublesome.
  • the effectiveness of the coating composition according to the invention is the use of an inorganic material in a thin coating which is easily wettable by the molten metal and easily removable under the action of the molten metal. Because the coating is slightly wetted by the metal, the metal easily passes through the ceramic body and also the tortuous flow paths in the ceramic body when the preferred ceramic foam material is used, and the casting time and the metal excess can be considerably reduced.
  • the coated composition does not merely reduce the casting time. Rather, it was found that the coated filters surprisingly bring about a faster flow of the filtering process, for example the total material flow through the ceramic body according to the present invention is generally faster than through an uncoated ceramic body.
  • filters according to the present invention retain a higher flow rate after casting than uncoated filters. This is despite the fact that the coating is removed on contact with the molten metal. This may be caused by the faster casting of the entire ceramic filter and the faster flow through all pores in the ceramic filter body. This also represents a progress worth considering.
  • Bound ceramic filter body 18.7 mm thick, with an open cell structure, characterized by a large number of interconnected cavities, surrounded by a A network of ceramics, the filter body being based on an aluminum oxide ceramic, is predetermined. These filters used had 10 pores per cm. Samples of the filters were coated in accordance with the present invention by immersing the filter bodies in an aqueous dispersion containing 1% colloidal silicon dioxide for a short period of time, which ensured complete impregnation, in order to obtain a thin coating, dried at 121 ° C and baked at 1000 ° C. The thickness of the coating after firing was around 10 ⁇ and the coating was present in aggregates of silicon dioxide particles essentially distributed throughout the entire ceramic body.
  • Coated and uncoated filters 1.86 cm thick, were placed side by side in a pouring pan. Molten steel was directly from an induction oven poured into the casting crucible at a temperature of 1621 ° C. When the crucible is filled, the metallostatic pressure on the filter increases until the metal overhang reaches the height of the overflow. The time of filter wetting was determined by visual observation of the outflow side of the filter. The results showed that the coated filter wets 4 to 5 seconds earlier than an uncoated filter. The flow of the molten metal through the coated filter appeared to be very fluid, while the flow through the uncoated filter was very tough and slow in comparison.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Filtering Materials (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Abstract

Le corps du filtre en céramique présente une multitude de chemins de parcours pour le métal liquide et est revêtu d'une mince couche d'un matériau inorganique qui peut être facilement mouillé par le métal en fusion.
PCT/CH1987/000100 1986-08-28 1987-08-14 Filtre en ceramique pour le filtrage de metal en fusion Ceased WO1988001532A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BR8707442A BR8707442A (pt) 1986-08-28 1987-08-14 Filtros ceramicos para a filtracao de metal fundido
NO881756A NO881756L (no) 1986-08-28 1988-04-22 Keramisk filter for smeltet metall.
DK2279/88A DK227988D0 (da) 1986-08-28 1988-04-26 Keramiske filter til filtrering af smeltet metal

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US90143286A 1986-08-28 1986-08-28
US901,432 1986-08-28

Publications (1)

Publication Number Publication Date
WO1988001532A1 true WO1988001532A1 (fr) 1988-03-10

Family

ID=25414177

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CH1987/000100 Ceased WO1988001532A1 (fr) 1986-08-28 1987-08-14 Filtre en ceramique pour le filtrage de metal en fusion

Country Status (9)

Country Link
EP (1) EP0280695A1 (fr)
JP (1) JPS63503289A (fr)
CN (1) CN1011486B (fr)
AU (1) AU598025B2 (fr)
BR (1) BR8707442A (fr)
DK (1) DK227988D0 (fr)
ES (1) ES2005272A6 (fr)
WO (1) WO1988001532A1 (fr)
ZA (1) ZA876106B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020024367A (ko) * 2000-09-25 2002-03-30 김희영 수의과 수술용 드릴 및 그 연결축

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2599990B1 (fr) * 1986-03-19 1993-03-26 Ceramiques Composites Filtre pour metaux liquides a base de materiau ceramique alveolaire, son procede de preparation et son application a la filtration de metaux ou d'alliages liquides de tres haut point de fusion
DK2385871T3 (da) * 2010-03-19 2013-02-11 Foseco Int Fremgangsmåde til fremstilling af et ildfast filter
CN104826391A (zh) * 2015-04-21 2015-08-12 安徽凤凰滤清器股份有限公司 一种纳米陶瓷粉末基吸附过滤剂及其制作方法
CN110981539B (zh) * 2019-12-30 2021-11-16 武汉科技大学 含功能涂层多重孔结构的氧化镁基过滤器及其制备方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2439170A1 (fr) * 1978-10-21 1980-05-16 Bridgestone Tire Co Ltd Corps poreux ceramique pour le filtrage de metal fondu
US4395333A (en) * 1982-04-14 1983-07-26 Groteke Daniel E Pre-wet and reinforced molten metal filter
JPS60106514A (ja) * 1983-11-14 1985-06-12 Toyota Motor Corp 微粒子捕集用セラミツクフイルタ
GB2166758A (en) * 1984-11-08 1986-05-14 Bridgestone Corp Porous ceramic filter

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8322020D0 (en) * 1983-08-16 1983-09-21 Alcan Int Ltd Filtering molten metal

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2439170A1 (fr) * 1978-10-21 1980-05-16 Bridgestone Tire Co Ltd Corps poreux ceramique pour le filtrage de metal fondu
US4395333A (en) * 1982-04-14 1983-07-26 Groteke Daniel E Pre-wet and reinforced molten metal filter
JPS60106514A (ja) * 1983-11-14 1985-06-12 Toyota Motor Corp 微粒子捕集用セラミツクフイルタ
GB2166758A (en) * 1984-11-08 1986-05-14 Bridgestone Corp Porous ceramic filter

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Band 8, Nr. 156 (C-234) (1593), 19. Juli 1984, siehe die ganze Zusammenfassung & JP, A, 5962324 (Tdk K.K.) 9. April 1984 *
PATENT ABSTRACTS OF JAPAN, Band 9, Nr. 254 (C-308) (1977), 11. Oktober 1985, & JP, A, 60106514 (Toyota Jidosha K.K.) 12. Juni 1985 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020024367A (ko) * 2000-09-25 2002-03-30 김희영 수의과 수술용 드릴 및 그 연결축

Also Published As

Publication number Publication date
AU598025B2 (en) 1990-06-14
CN1011486B (zh) 1991-02-06
AU7784487A (en) 1988-03-24
BR8707442A (pt) 1988-11-01
CN87106034A (zh) 1988-03-16
EP0280695A1 (fr) 1988-09-07
ES2005272A6 (es) 1989-03-01
ZA876106B (en) 1988-02-23
JPS63503289A (ja) 1988-12-02
DK227988A (da) 1988-04-26
DK227988D0 (da) 1988-04-26

Similar Documents

Publication Publication Date Title
DE2932614C2 (de) Poröse Keramikkörper, Verfahren zu deren Herstellung und deren Anwendung
DE3219782C2 (fr)
DE3040754C2 (de) Poröser Keramikkörper, Verfahren zu dessen Herstellung und dessen Anwendung
DE2613023C2 (de) Poröses Keramikfilter zum Filtrieren von Metallschmelzen
DE3120582C2 (de) Kokille mit wärmeisolierender Schutzschicht
DE1758845C3 (de) Verfahren zur Herstellung von Prazisions gießformen fur reaktionsfähige Metalle
EP0305455A1 (fr) Filtre spongieux en ceramique.
DE2838504A1 (de) Vorrichtung zum filtrieren von geschmolzenem metall
EP0058812A2 (fr) Filtre poreux céramique et procédé pour sa fabrication
EP0029802A1 (fr) Filtre céramique à structure mousseuse pour le filtrage de métal fondu
DE60016093T2 (de) Keramikmembran
DE3539522A1 (de) Poroese keramikstruktur
DE2157845A1 (de) Verfahren zur Herstellung von feuer festen Gegenstanden und feuerfeste Matenalmischung
DE3009490C2 (fr)
DE2637508A1 (de) Filter fuer geschmolzene metalle, verfahren zu seiner herstellung, und seine verwendung
DE1185775B (de) Verfahren zum Herstellen von Praezisionsgiessformen mit Ausschmelzmodellen
WO1988001532A1 (fr) Filtre en ceramique pour le filtrage de metal en fusion
DE1458315B2 (de) Verfahren zur Herstellung poröser, gesinterter Formkörper aus einer Al-Cu-Legierung
DE3200104C2 (de) Gießvorrichtung zum Herstellen von legierten Metallgußstücken
DE102021123320A1 (de) Verfahren zum Hochtemperaturverzinken von Eisenwerkstoffteilen
DE2219096A1 (de) Gießrinne
DE4139004C2 (de) Verfahren zur Herstellung einer supraleitenden oxidkeramischen Röhre
JP2514006B2 (ja) 除滓能力に優れた網状フイルタ−
DE2714466A1 (de) Verfahren zum anreichern von alkali-wismutid in einem geschmolzenes blei enthaltenden material
DE1433969B2 (de) Fluorhaltige schutzschicht fuer giessformen und verfahren zu ihrer herstellung

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU BR DK JP NO

AL Designated countries for regional patents

Kind code of ref document: A1

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

WWE Wipo information: entry into national phase

Ref document number: 1987904834

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1987904834

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1987904834

Country of ref document: EP