EP1481115B1 - Graphitierte kathodenblöcke - Google Patents
Graphitierte kathodenblöcke Download PDFInfo
- Publication number
- EP1481115B1 EP1481115B1 EP02796687A EP02796687A EP1481115B1 EP 1481115 B1 EP1481115 B1 EP 1481115B1 EP 02796687 A EP02796687 A EP 02796687A EP 02796687 A EP02796687 A EP 02796687A EP 1481115 B1 EP1481115 B1 EP 1481115B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cathode
- joined
- cathode blocks
- parts
- blocks
- 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 - Fee Related
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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 graphitized cathode blocks, a process for their preparation and their Use in particular for the electrolytic production of aluminum.
- electrolytic cells which is composed of a plurality of blocks Soil, which acts as a cathode.
- the electrolyte is a melt, essentially one Solution of alumina in cryolite.
- the working temperature is for example at approx. 1000 ° C.
- the electrolytically deposited molten aluminum collects on the Bottom of the cell under a layer of the electrolyte.
- Around the cells is a metallic one Housing (preferably steel) with a lining of high temperature resistant material.
- the material of the cathode blocks is because of the required chemical and thermal Resistance prefers carbon partially or partially by thermal treatment can be completely graphitized.
- For the preparation of such cathode blocks are 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 burning (carbonation) is usually at Temperatures of about 1200 ° C, the graphitization usually at temperatures of over 2400 ° C.
- While graphitized cathodes are preferred because of their higher electrical conductivity they show a greater erosion during operation, according to a medium annual decrease in their thickness of up to 80 mm. This wear is not uniform across the length of the cathode blocks (corresponding to the width of the cell) distributed, but changed the surface of the cathode blocks to a W-shaped profile. By the uneven Ablating the service life of the cathode blocks is limited by the points with the largest removal.
- One way to equalize the removal over the length of the cathode block and To extend the useful life is to make the cathode blocks so that their electrical resistance varies over the length, so that the current density (and thus the Wear) is uniform over its length or at least the smallest possible deviation over the length of its mean.
- composite cathodes formed are either made of several carbon blocks with different electrical Conductivity, which are arranged so that a uniform or approximate uniform current distribution results, or from carbon blocks whose electrical Resistances in the direction of the cathodic leads continuously increase.
- the number The carbon blocks and their electrical resistance depend on cell size and cell type, they have to be recalculated for each case.
- Cathode blocks from one Variety of single carbon blocks require a lot of effort in the Construction; Also, the joints must each be well sealed to an outflow to avoid the liquid aluminum at the joints.
- a graphite cathode which consists of a single Block consists, which has a variable over its length electrical conductivity, wherein the conductivity at the ends of the block is lower than in the middle.
- This uneven Distribution of the electrical conductivity is achieved by the during graphitization End zones are brought to a temperature of 2200 to 2500 ° C, while the middle Zone is exposed to a temperature of 2700 to 3000 ° C.
- These different Heat treatment can be achieved according to this teaching by two ways: once can the heat dissipation in the graphitizing furnace are limited differently, or it can Heat sinks are introduced in the neighborhood of the end zones, which reduces the heat loss increase.
- a transverse graphitization is the density of the heat-insulating bed changed so that the heat loss over the length of the cathode is uneven and to set the desired temperatures.
- Even with the longitudinal graphitization can by different execution of the heat-insulating bed of heat loss in the Be increased near the ends, or it will be for this purpose heat dissipating body preferably made of graphite introduced in their vicinity, which has a greater heat flow to the outside effect towards the furnace wall.
- the difference of the heat treatment may be due to local change the current density, with the result of different heat development.
- Change in the current density can, according to the teaching by different resistances of the conductive bed between two cathodes in an Acheson furnace (cross graphitization) For a longitudinal graphitization process no such solution is given.
- cathode blocks are graphitized by the longitudinal grafting method, the result is at the joints of the individual cathode blocks with each other or between them arranged electrically conductive connecting elements an electrical transition with a against the resistance inside the individual cathode blocks or the Connecting element increased resistance.
- This increased resistance leads to increased Heat development and thus to higher temperature, ie an acceleration of the Graphit michsre redesign. Therefore, the electrical resistance in longitudinal graphitization at the Ends of the cathode blocks usually lower than that in the middle of the cathode blocks. This distribution of the resistance or the electrical conductivity over the length of Cathode blocks is just the opposite of the desired course.
- cathode blocks with the desired course to simple Make way by placing the above-described cathode blocks in the middle cuts apart and reassembles in the opposite direction. This results in a Profile of the electrical resistance in the form of a rounded V at the thighs.
- the present invention therefore provides graphitized cathode blocks for the production of aluminum by electrolytic reduction of alumina in a bath of molten cryolite, characterized in that the cathode blocks consist of two parts are assembled and along their length a V-shaped profile of their electrical resistance wherein the resistor in the middle of the cathode blocks has a point of discontinuity and steadily increasing towards the ends, such that the resistance at the ends of the Parts in the middle in the ratio of at least 1.05: 1 stands.
- the cathode blocks are composed of two parts whose electrical Resistance increases steadily over its length, so that the resistance at the ends of the parts to in the middle in the ratio of at least 1.15: 1. This is particularly preferred Ratio 1.3: 1.
- FIG. 1 shows the course of the specific electrical resistance ⁇ , shown in the interior of the side view of a cathode block 4, calculated as ( R a / l), where R is the electrical resistance of a parallelepiped specimen, a its cross-sectional area, and l its length , over the length of the cathode block.
- the ends of the block, as obtained in longitudinal graphitization, are designated A.
- the cathode block is cut apart along the line BB, the end faces at A are denoted as 4-1 , and the parting line along the line BB in the side cut is called 4-2 .
- the separated cathode block is then assembled as shown in Figs. 2 to 4, that the ends A and the end faces 4-1 are located in the center of the assembled cathode block.
- Fig. 2 shows an embodiment, wherein between the two ends now located in the middle A with the end faces 4-1 is a layer of ramming mass 5 , which otherwise also to seal the contact surfaces between the individual cathode blocks at the bottom of the tub of the electrolysis cell is used.
- a further preferred embodiment is shown, in which case the two half-blocks are joined together in each case with the ends A by a layer of an adhesive 6 with the required temperature resistance.
- Suitable adhesives are cold-curing resins such as BVK6 from SGL Carbon AG.
- FIG. 4 shows an embodiment in which an adhesive or intermediate layer was dispensed with, and the two half-blocks were joined together only with their ends A.
- the required surface pressure is applied in this case by the thermal expansion of the half-blocks, which are pressed together after flush installation in the electrolysis cells during heating. It has been found that the pressing force is greater enough to ensure a secure and tight connection of the two half-blocks, if the end surfaces were sufficiently flat prior to the division.
- the graphitized cathode blocks according to the invention show in the production of Aluminum by electrolytic reduction of alumina in a bath of molten cryolite over the conventional homogeneous distribution of electrical conductivity a more uniform wear over the length of the cathode and therefore a significantly increased service life.
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)
Description
- Fig. 1
- den Verlauf des spezifischen elektrischen Widerstandes ρ über die Länge des Kathodenblocks, wie er sich bei der Längsgraphitierung mit hohem Übergangswiderstand zwischen den einzelnen Kathodenblöcken ergibt, in die Seitenansicht eines Kathodenblocks eingezeichnet,
- Fig. 2
- eine Seitenansicht eines in der Mitte auseinandergetrennten und umgekehrt zusammengesetzten Kathodenblocks, wobei in der Mitte eine Verbindungsschicht aus Stampfmasse eingebracht ist,
- Fig. 3
- eine Seitenansicht eines in der Mitte auseinandergetrenmen und umgekehrt zusammengesetzten Kathodenblocks, wobei in der Mitte eine Klebefuge die beiden Teile verbindet, und
- Fig. 4
- eine Seitenansicht eines in der Mitte auseinandergetrennten und umgekehrt zusammengesetzten Kathodenblocks, wobei die beiden Teile lediglich bündig aneinandergesetzt sind.
Claims (9)
- Graphitierte Kathodenblöcke zur Herstellung von Aluminium durch elektrolytische Reduktion von Aluminiumoxid in einem Bad von geschmolzenem Kryolith, dadurch gekennzeichnet, daß die Kathodenblöcke aus zwei Teilen zusammengesetzt sind und über ihre Länge ein V-förmiges Profil ihres spezifischen elektrischen Widerstandes aufweisen, wobei der Widerstand in der Mitte der Kathodenblöcke eine Unstetigkeitsstelle aufweist und zu den Enden hin stetig zunimmt, derart daß der Widerstand an den Enden der Teile zu dem in der Mitte im Verhältnis von mindestens 1,05 : 1 steht.
- Graphitierte Kathodenblöcke nach Anspruch 1, dadurch gekennzeichnet, daß die Kathodenblöcke aus zwei Teilen zusammengesetzt sind, wobei die Kontaktflächen der Teile durch mechanische Pressung verbunden sind.
- Graphitierte Kathodenblöcke nach Anspruch 1, dadurch gekennzeichnet, daß die Kathodenblöcke aus zwei Teilen zusammengesetzt sind, wobei die Kontaktflächen der Teile durch eine Stampfmasse verbunden sind.
- Graphitierte Kathodenblöcke nach Anspruch 1, dadurch gekennzeichnet, daß die Kathodenblöcke aus zwei Teilen zusammengesetzt sind, wobei die Kontaktflächen der Teile verklebt sind.
- Verfahren zur Herstellung von graphitierten Kathodenblöcke gemäß Anspruch 1, dadurch gekennzeichnet, daß ein graphitierter Kathodenblock, dessen elektrische Leitfähigkeit über die Länge dem Profil eines flachen U entspricht, mittig getrennt und mit den ursprünglichen Außenseiten nach innen gerichtet wieder zusammengesetzt wird.
- Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß der zusammengesetzte Kathodenblock durch mechanische Pressung in der Elektrolysezelle verbunden wird
- Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß der zusammengesetzte Kathodenblock durch die thermische Ausdehnung in der Elektrolysezelle verbunden wird.
- Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß der zusammengesetzte Kathodenblock durch Stampfmasse in der Mitte verbunden wird.
- Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß der zusammengesetzte Kathodenblock in der Mitte verklebt wird.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2001164008 DE10164008C1 (de) | 2001-12-28 | 2001-12-28 | Graphitierte Kathodenblöcke |
DE10164008 | 2001-12-28 | ||
PCT/EP2002/014548 WO2003056068A2 (de) | 2001-12-28 | 2002-12-19 | Graphitierte kathodenblöcke |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1481115A2 EP1481115A2 (de) | 2004-12-01 |
EP1481115B1 true EP1481115B1 (de) | 2005-12-07 |
Family
ID=7710902
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP02796687A Expired - Fee Related EP1481115B1 (de) | 2001-12-28 | 2002-12-19 | Graphitierte kathodenblöcke |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP1481115B1 (de) |
AR (1) | AR037912A1 (de) |
AU (1) | AU2002361174A1 (de) |
BR (1) | BR0215323A (de) |
CA (1) | CA2470753A1 (de) |
DE (2) | DE10164008C1 (de) |
PL (1) | PL201672B1 (de) |
WO (1) | WO2003056068A2 (de) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102011076302A1 (de) | 2011-05-23 | 2013-01-03 | Sgl Carbon Se | Elektrolysezelle und Kathode mit unregelmäßiger Oberflächenprofilierung |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2728109A (en) * | 1952-06-06 | 1955-12-27 | Savoie Electrodes Refract | Method of making cathodic electrodes for electrolysis furnaces |
US4194959A (en) * | 1977-11-23 | 1980-03-25 | Alcan Research And Development Limited | Electrolytic reduction cells |
NO157462C (no) * | 1985-10-24 | 1988-03-23 | Hydro Aluminium As | Laminert karbonkatode for celler til smelte-elektrolytisk fremstilling av aluminium. |
US4795540A (en) * | 1987-05-19 | 1989-01-03 | Comalco Aluminum, Ltd. | Slotted cathode collector bar for electrolyte reduction cell |
FR2789091B1 (fr) * | 1999-02-02 | 2001-03-09 | Carbone Savoie | Cathode graphite pour l'electrolyse de l'aluminium |
EP1233083A1 (de) * | 2001-02-14 | 2002-08-21 | Alcan Technology & Management AG | Kohleboden einer Elektrolysezelle zur Gewinnung von Aluminium |
-
2001
- 2001-12-28 DE DE2001164008 patent/DE10164008C1/de not_active Expired - Fee Related
-
2002
- 2002-12-18 AR ARP020104963 patent/AR037912A1/es unknown
- 2002-12-19 BR BR0215323-8A patent/BR0215323A/pt not_active IP Right Cessation
- 2002-12-19 CA CA002470753A patent/CA2470753A1/en not_active Abandoned
- 2002-12-19 PL PL369969A patent/PL201672B1/pl not_active IP Right Cessation
- 2002-12-19 WO PCT/EP2002/014548 patent/WO2003056068A2/de active IP Right Grant
- 2002-12-19 EP EP02796687A patent/EP1481115B1/de not_active Expired - Fee Related
- 2002-12-19 AU AU2002361174A patent/AU2002361174A1/en not_active Abandoned
- 2002-12-19 DE DE50205232T patent/DE50205232D1/de not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
EP1481115A2 (de) | 2004-12-01 |
DE10164008C1 (de) | 2003-04-30 |
BR0215323A (pt) | 2004-10-19 |
PL369969A1 (en) | 2005-05-02 |
CA2470753A1 (en) | 2003-07-10 |
AU2002361174A1 (en) | 2003-07-15 |
DE50205232D1 (de) | 2006-01-12 |
AR037912A1 (es) | 2004-12-22 |
WO2003056068A2 (de) | 2003-07-10 |
WO2003056068A3 (de) | 2004-09-30 |
PL201672B1 (pl) | 2009-04-30 |
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