WO2003056070A1 - Procede de graphitisation de blocs cathodiques - Google Patents

Procede de graphitisation de blocs cathodiques Download PDF

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Publication number
WO2003056070A1
WO2003056070A1 PCT/EP2002/014550 EP0214550W WO03056070A1 WO 2003056070 A1 WO2003056070 A1 WO 2003056070A1 EP 0214550 W EP0214550 W EP 0214550W WO 03056070 A1 WO03056070 A1 WO 03056070A1
Authority
WO
WIPO (PCT)
Prior art keywords
cathode blocks
graphitization
cathode
blocks
conductive bodies
Prior art date
Application number
PCT/EP2002/014550
Other languages
German (de)
English (en)
Inventor
Johann Daimer
Frank Hiltmann
Jörg MITTAG
Original Assignee
Sgl Carbon 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
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First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=7710907&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO2003056070(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Sgl Carbon Ag filed Critical Sgl Carbon Ag
Priority to CA002470757A priority Critical patent/CA2470757A1/fr
Priority to BR0215322-0A priority patent/BR0215322A/pt
Priority to AU2002361175A priority patent/AU2002361175A1/en
Priority to EP02796688A priority patent/EP1461476A1/fr
Publication of WO2003056070A1 publication Critical patent/WO2003056070A1/fr

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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 invention relates to a method for graphitizing cathode blocks, in particular for the electrolytic production of aluminum.
  • electrolytic cells which comprise a base composed of a multiplicity of blocks, which acts as a cathode.
  • the electrolyte is a melt, essentially a solution of aluminum oxide in cryolite.
  • the working temperature is around 1000 ° C, for example.
  • the electrolytically deposited molten aluminum collects on the bottom of the cell under a layer of the electrolyte.
  • Around the cells is a metallic housing (preferably steel) with a lining made of high temperature resistant material.
  • the material of the cathode blocks is preferably carbon because of the required chemical and thermal resistance, which can be partially or completely graphitized by thermal treatment.
  • mixtures of pitches, cokes, anthracite and / or graphite in selected particle sizes or particle size distributions for the solids are mixed, shaped and fired and optionally (partially) graphitized.
  • the firing (carbonization) usually takes place at temperatures of approx. 1200 ° C, the graphitization usually at temperatures of approx. 2400 ° C.
  • While graphitized cathodes are preferred because of their higher electrical conductivity, they show greater wear during operation, corresponding to an average annual decrease in their thickness of up to 80 mm. This wear is not evenly distributed over the length of the cathode blocks (corresponding to the width of the cell), but changes the surface of the cathode blocks into a W-shaped profile. Due to the uneven removal, the service life of the cathode blocks is limited by the places with the greatest removal.
  • One way to equalize the removal over the length of the cathode block and thus to extend the service life is to design the cathode blocks so that their electrical resistance varies over the length such that the current density (and thus the Wear) is uniform over its length or at least exhibits the smallest possible deviation over the length from its mean value.
  • a solution is described in DE 20 61 263, in which composite cathodes are formed either from several carbon blocks with different electrical conductivity, which are arranged in such a way that a uniform or approximately uniform current distribution results, or from carbon blocks, the electrical resistances of which are in the direction of the cathodic Derivatives increase continuously.
  • the number of carbon blocks and their electrical resistance depend on the cell size and cell p, they must be recalculated for each case.
  • Cathode blocks made of a large number of individual carbon blocks require a great deal of effort in the construction; the joints must also be properly sealed to prevent the liquid aluminum from flowing out at the joints.
  • WO 00/46426 describes a graphite cathode which consists of a single block which has an electrical conductivity which is variable over its length, the conductivity at the ends of the block being lower than in the middle.
  • This uneven distribution of electrical conductivity is achieved by bringing the end zones to a temperature of 2200 to 2500 ° C. during the graphitization, while exposing the middle zone to a temperature of 2700 to 3000 ° C.
  • This different heat treatment can be achieved according to this teaching in two ways: first, the heat dissipation in the graphitization furnace can be limited differently, or heat sinks can be introduced in the vicinity of the end zones, which increase the heat loss.
  • the density of the heat-insulating bed is changed so that the heat loss becomes uneven over the length of the cathodes and the desired temperatures are thus set.
  • the heat loss in the vicinity of the ends can be increased by different designs of the heat-insulating bed, or for this purpose heat-dissipating bodies made of graphite are preferably introduced in their vicinity, which cause a greater heat flow to the outside of the furnace wall.
  • the difference in the heat treatment can be done by locally changing the current density, with the result of different heat development.
  • this change in the current density can take place through different resistances of the conductive bed between two cathodes in an Acheson furnace (quenched graphitization); no solution of this type is specified for a longitudinal graphitization process.
  • the object is achieved by a method for graphitizing cathode blocks, in which the current is transferred from one of the cathode blocks to the adjacent one via conductive contact bodies, each of which has a contact surface for each of the two adjacent cathode blocks and a yoke connecting the two surfaces.
  • the distance between the end faces of two successive cathode blocks is at least 25 mm and at most 150 mm.
  • Two cathode blocks each lie on the conductive contact bodies in such a way that the contact between them and the cathode blocks is mediated by the weight that acts on the cathode blocks.
  • the contact bodies are preferably designed such that they show the profile of an H in the side view, without the two lower legs, the cathode blocks resting on the contact bodies in such a way that they press on them by their weight and thereby apply the surface pressure required for the power line ,
  • the contact bodies for the method are preferably designed such that the contact surface of the cathode blocks on the conductive contact bodies is in each case at least 12,500 and at most 250,000 mm 2 .
  • the conductive contact bodies must withstand the high temperatures that occur and should also have the highest possible conductivity. Such bodies have proven themselves, which consist of at least 50% of their mass of graphite. Bodies which consist of more than 80% graphite are particularly preferred; bodies which consist of pure graphite or of graphite with a maximum of 5% of their mass of admixtures are particularly suitable.
  • the conductive contact bodies have a specific electrical resistance of at most 8 ⁇ m.
  • the cathode blocks produced by the process according to the invention can be used in the electrolytic extraction of aluminum.

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

Abstract

L'invention concerne un procédé de graphitisation de blocs cathodiques, destinés à la production électrolytique d'aluminium, d'après la méthode de graphitisation en long. Ce procédé se caractérise en ce que les blocs cathodiques sont disposés dans un four de graphitisation en long de telle sorte que la distance entre leurs extrémités soit comprise entre 25 et 150 mm et en ce que le transfert de courant entre les différents blocs cathodiques se fasse par l'intermédiaire de corps conducteurs, les blocs cathodiques étant placés deux à deux sur les corps conducteurs de telle sorte que le contact entre ces blocs et lesdits corps soit établi par l'intermédiaire de la force de gravité s'exerçant sur les blocs cathodiques. L'invention concerne en outre les blocs cathodiques obtenus par ce procédé, ainsi que leur utilisation pour la réduction électrolytique d'oxyde d'aluminium.
PCT/EP2002/014550 2001-12-28 2002-12-19 Procede de graphitisation de blocs cathodiques WO2003056070A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002470757A CA2470757A1 (fr) 2001-12-28 2002-12-19 Procede de graphitisation de blocs cathodiques
BR0215322-0A BR0215322A (pt) 2001-12-28 2002-12-19 Processo para grafitização de blocos de catodo
AU2002361175A AU2002361175A1 (en) 2001-12-28 2002-12-19 Method for the graphitization of cathode blocks
EP02796688A EP1461476A1 (fr) 2001-12-28 2002-12-19 Procede de graphitisation de blocs cathodiques

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10164013.7 2001-12-28
DE2001164013 DE10164013C1 (de) 2001-12-28 2001-12-28 Verfahren zum Graphitieren von Kathodenblöcken

Publications (1)

Publication Number Publication Date
WO2003056070A1 true WO2003056070A1 (fr) 2003-07-10

Family

ID=7710907

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2002/014550 WO2003056070A1 (fr) 2001-12-28 2002-12-19 Procede de graphitisation de blocs cathodiques

Country Status (8)

Country Link
EP (1) EP1461476A1 (fr)
AR (1) AR037917A1 (fr)
AU (1) AU2002361175A1 (fr)
BR (1) BR0215322A (fr)
CA (1) CA2470757A1 (fr)
DE (1) DE10164013C1 (fr)
PL (1) PL368809A1 (fr)
WO (1) WO2003056070A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10164011C1 (de) * 2001-12-28 2003-05-08 Sgl Carbon Ag Verfahren zum Graphitieren von Kathodenblöcken
DE102010029538A1 (de) * 2010-05-31 2011-12-01 Sgl Carbon Se Kohlenstoffkörper, Verfahren zur Herstellung eines Kohlenstoffkörpers und seine Verwendung

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3787311A (en) * 1970-12-12 1974-01-22 Giulini Gmbh Geb Cathode for the winning of aluminum
DE3606380A1 (de) * 1986-02-27 1987-09-03 Sigri Gmbh Hochstromofen zum graphitieren von kohlenstoffkoerpern
FR2789091A1 (fr) * 1999-02-02 2000-08-04 Carbone Savoie Cathode graphite pour l'electrolyse de l'aluminium
US6231745B1 (en) * 1999-10-13 2001-05-15 Alcoa Inc. Cathode collector bar
US20020000373A1 (en) * 2000-05-22 2002-01-03 Hirofumi Ninomiya Graphitized cathode block for aluminum smelting

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3787311A (en) * 1970-12-12 1974-01-22 Giulini Gmbh Geb Cathode for the winning of aluminum
DE3606380A1 (de) * 1986-02-27 1987-09-03 Sigri Gmbh Hochstromofen zum graphitieren von kohlenstoffkoerpern
FR2789091A1 (fr) * 1999-02-02 2000-08-04 Carbone Savoie Cathode graphite pour l'electrolyse de l'aluminium
US6231745B1 (en) * 1999-10-13 2001-05-15 Alcoa Inc. Cathode collector bar
US20020000373A1 (en) * 2000-05-22 2002-01-03 Hirofumi Ninomiya Graphitized cathode block for aluminum smelting

Also Published As

Publication number Publication date
AU2002361175A1 (en) 2003-07-15
EP1461476A1 (fr) 2004-09-29
AR037917A1 (es) 2004-12-22
CA2470757A1 (fr) 2003-04-10
PL368809A1 (en) 2005-04-04
DE10164013C1 (de) 2003-04-03
BR0215322A (pt) 2004-10-19

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