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EP1531194A1 - Blocs cathodiques avec dispositif de détection d'usure pour l'électrolyse de l'aluminium - Google Patents

Blocs cathodiques avec dispositif de détection d'usure pour l'électrolyse de l'aluminium Download PDF

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Publication number
EP1531194A1
EP1531194A1 EP03026223A EP03026223A EP1531194A1 EP 1531194 A1 EP1531194 A1 EP 1531194A1 EP 03026223 A EP03026223 A EP 03026223A EP 03026223 A EP03026223 A EP 03026223A EP 1531194 A1 EP1531194 A1 EP 1531194A1
Authority
EP
European Patent Office
Prior art keywords
holes
cathode
block
cathode blocks
tracer
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.)
Withdrawn
Application number
EP03026223A
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German (de)
English (en)
Inventor
Philippe Beghein
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.)
SGL Carbon SE
Original Assignee
SGL Carbon SE
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 SGL Carbon SE filed Critical SGL Carbon SE
Priority to EP03026223A priority Critical patent/EP1531194A1/fr
Priority to JP2004325845A priority patent/JP4755409B2/ja
Priority to BRPI0405016 priority patent/BRPI0405016A/pt
Publication of EP1531194A1 publication Critical patent/EP1531194A1/fr
Withdrawn legal-status Critical Current

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    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/08Cell construction, e.g. bottoms, walls, cathodes

Definitions

  • the invention relates to cathode blocks for aluminium electrolysis cells having a wear detection functionality of by incorporation of tracer materials.
  • Aluminium is conventionally produced by the Hall-Heroult process, by the electrolysis of alumina dissolved in cryolite-based molten electrolytes at temperatures up to around 950 °C.
  • a Hall-Heroult reduction cell typically has a steel shell provided with an insulating lining of refractory material, which in turn has a lining of carbon contacting the molten constituents.
  • Conductor bars connected to the negative pole of a direct current source are embedded in the carbon cathode substrate forming the cell bottom floor.
  • the cathode substrate is usually constituted of blocks made of carbon or graphite, joined with a ramming mixture of anthracite, coke, and coal tar.
  • a molten aluminium pool acts as the cathode.
  • the carbon lining or cathode material has a useful life of four to ten years, or even less under adverse conditions.
  • the deterioration of the cathode bottom is due to erosion and penetration of electrolyte and liquid aluminium as well as intercalation of sodium, which causes swelling and deformation of the cathode blocks and ramming mixture.
  • the erosion of the cathode block does not occur evenly across the block length but shapes the block surface into a W-profile. Erosion in graphite cathodes may progress at a rate of up to 60 mm per annum. Due to resulting cracks in the cathode blocks, aluminium reaches the steel cathode conductor bars causing corrosion thereof leading to deterioration of the electrical contact, non-uniformity in current distribution and an excessive iron content in the aluminium metal produced.
  • a machine condition diagnostic system wherein a distinct tracer element indicator material labels each wearable machine components.
  • the lubricant is monitored and periodically or continually sampled to determine the presence of abnormal levels in the amount of indicator material. Since each component or components performing a similar function is labelled with the same indicator, the presence of a particular indicator in abnormal amounts in the lubricant directs the machine operator to the precise location requiring repair or replacement.
  • the indicator material is introduced by drilling a bore into the race surface of each bearing in a machine to beyond the depth of maximum acceptable wear, inserting a pill comprised of an indicator material into the bottom of said bore so that each bearing function is represented by a different indicator pill, and sealing said bore.
  • Preferred tracer elements for bronze or brass bearings include but are not restricted to aluminium, beryllium, bismuth, carbon, cobalt, chromium and zirconium.
  • cathode blocks providing a detection functionality for indicating extent of cathode wear in aluminium electrolysis cells without interrupting the cell operation. Another object of this invention is to provide cathode blocks permitting a detection functionality indicating the wear progression at distinctive locations within the cathode block. It is a further object of this invention to place cathode blocks with wear detection functionality in an electrolysis cell in order to monitor wear progression at distinctive locations throughout the cell.
  • the task of the invention is solved by providing a detection functionality for indicating extent of cathode wear in aluminium electrolysis cells without interrupting the cell operation by introduction of tracer materials into the cathode block which are leached out by penetrating aluminium and can be detected by analytical techniques.
  • One advantage of this invention is to circumvent the difficulties in implementing direct detection methods usually being based on electrical signals by utilizing standard product quality test methods.
  • a standard analytical method utilised in this quality test is Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES).
  • ICP-AES Inductively Coupled Plasma Atomic Emission Spectroscopy
  • the plasma used in this technique is able to excite many different elements, making ICP-AES a highly effective multi-element detection technique.
  • the ICP-AES detection limits vary from 1 to 100 ppb. This technique also provides low detection limits for a lot of high melting elements such as B and Ti.
  • ICP-AES as a standard test in aluminium electrolysis cells, can be utilised for the indirect detection of cathode block wear. Tracer materials introduced into the cathode blocks are leached out by penetrating aluminium and can be detected even at very low levels by ICP-AES. Whereas ICP-AES is the preferred analytical technique, various other analytical methods can be employed for the same purpose according to this invention.
  • Another advantage of this invention is the accurate pre-warning time it provides to the electrolysis operators to prepare the required shutdown procedures.
  • electrolysis cells have either been shut down too early or only after the produced aluminium had already been contaminated with iron from the current collector bars.
  • this invention provides means to monitor the wear progression at distinctive locations within the cathode block as well as throughout the electrolysis cell. This option opens the opportunity to decide individually on exchange of cathode blocks or to adjust operational parameters to achieve more homogeneous erosion throughout the electrolysis cell.
  • Tracer materials can be placed into the cathode blocks by means of holes.
  • the holes can be incorporated in to the cathode block by drilling of the finished block or by introduction of sacrificial material of adequate shape into the raw cathode block prior to carbonisation and graphitisation.
  • the hole positions are determined by the preferred tracer materials position. The size of those holes is mostly dependent from the amount of tracer material required for effective detection. It was found that a volume of 15 to 30 cm 3 tracer material has to be inserted in each cathode block to provide enough tracer elements to be detected by ICP-AES under typical production test conditions.
  • the tracer material has preferably to be positioned in the region where erosion is the highest. Erosion progresses from the cathode block surface in a non-uniform manner resulting in a so-called W-profile.
  • a typical W-profile erosion pattern (3) is indicated progressing from the top of a cathode block (1) down towards the steel-made collector bars (2) at the bottom of this block.
  • the best region to position the tracer material is located below the two negative peaks of the W-profile 200 to 500 mm away from both opposing end faces of the block.
  • cathode blocks (1) especially of graphite blocks
  • the erosion of cathode blocks (1) progresses typically at a rate of 40 mm per annum. It is therefore necessary, as shown in Figure 2, to position the holes (4) for the tracer material just a short distance above the steel-made current collector bars (2) to accurately give 2 to 4 weeks pre-warning time to plan for production shut-down and replacement of the entire electrolysis cell bottom.
  • the tracer-filled holes (4) should preferably be 2 to 5 mm deep and have 6 to 20 cm in diameter. This diameter range coincides with the width of the collector bars (2). In practice, the hole diameter will not exceed the width of the collector bar slot, yet a large enough portion of the collector bar surface should be covered for detection.
  • the hole diameter ranges from 30 to 100%, most preferably from 70 to 90%, of the slot width.
  • This embodiment is not limited to circular holes, any other hole shape can be used in the same manner as described.
  • Such prepared cathode blocks are later fitted with collector bars.
  • vertical holes (5) can be incorporated in the space between the collector bar slots, their depth exceeding the slot depth by 2 to 5 mm.
  • the hole diameter is determined by the web width in between the slots ranging from 30 to 85%, most preferably from 50 to 70%, of the web width.
  • Another object of this invention is to insert tracer materials at several distinctive distances from the top block surface thus providing means for a time-dependent monitoring of the erosion progress.
  • the tracer materials are positioned at different levels with distances of each 20 to 50 mm starting at 20 to 50 mm below the top block surface.
  • different tracer elements can be introduced at various positions inside the cathode blocks to facilitate not only time-dependent monitoring of the erosion progress but also providing the option for discriminating erosion effects at different positions within the cathode blocks.
  • the same principle applies to labelling of distinctive cathode blocks by different tracer elements for discrimination of erosion effects at different cathode blocks throughout the entire electrolysis cell.
  • This required tracer material volume will be taken up by holes of 0,8 to 1,2 cm diameter.
  • the depth of the holes can range from 200 to 500 mm depending mainly on the size of the cathode block and the required position of the tracer material inside the block.
  • transversal holes (6) can be positioned either as dead-end holes or as open holes across the entire width of the cathode block. After filling 50 to 90% of the hole volumes with tracer material, the holes are sealed by using ramming paste which is later also used for filling the small seams in between the cathode blocks. Alternatively, graphite plugs can seal the holes.
  • horizontal holes (7) are positioned starting from the end face of the cathode block. Such holes need to have a depth of 300 to 500 mm thus covering the entire region where erosion is typically highest. After filling 50 to 90% of hole volumes with tracer material, the holes are sealed by using ramming paste or graphite plugs.
  • the tracer elements to be utilised according to this invention can be selected from a wide range of chemical elements, expect for Iron (Fe), which is the main constituent of the steel collector bars.
  • This choice includes, but is not limited to, metals starting from atomic number 21 (scandium) up to atomic number 83 (bismuth).
  • Preferred are chemical elements that are readily available and are significantly heavier than aluminium in order to provide easy discrimination at ICP-AES analysis.
  • the hot aluminium upon contact should preferably easily take up those elements.
  • more preferred choices of tracer elements are the metals in the row from atomic number 22 (titanium) to 30 (zinc).
  • the chemical composition of the tracer elements is not limited to the pure element. Depending on price, toxicity, chemical reactivity and other factors, the tracer element can be provided in the form of, but is not limited to, salts, oxides, carbides, and alloys. Different tracer materials can also be mixed with each other or with neutral matrix materials before introduction into the cathode block. Neutral matrix materials are graphite or aluminium.
  • the physical appearance of the tracer material can vary between, but is not limited to, powders and wires or rods.
  • Powders can be fed into the holes and compacted by means of a rod or other devices. Wires or rods are being pushed into the hole.
  • the tracer material can be cast into the holes.
  • the tracer materials can also be introduced into dead-end holes as a salt solution, thus impregnating the region around the hole end.
  • Single collector bar slots of 200 mm width and 150 mm depth were cut out from each block, followed by drilling of two 3 mm deep holes of 10 cm diameter into each slot at a distance of 400 mm from either opposing end faces. Tablets made of pre-compacted powder consisting of 95 w/w% zinc and 5 w/w % copper with dimensions fitting exactly to the holes were placed in each hole. 15 cm diameter pieces of 100 ⁇ m thick flexible graphite foil were fixed on top of each hole as cover. Afterwards, steel collector bars were fitted into the slot. The cathode blocks were placed into an aluminium electrolysis cell.
  • Cathode blocks trimmed to their final dimensions were manufactured according to example 1.
  • Two parallel collector bar slots of 150 mm width and 150 mm depth each were cut out from each block, followed by drilling of four 152 mm deep holes of 5 cm diameter into the middle of the 100 mm wide web between both slots, whereby one opposing hole pair was positioned at 300 mm and the other at 400 mm away from either opposing end faces.
  • Each hole was filled with 25 g of CuCl powder and was then sealed by a graphite rod of 5 cm diameter and 150 mm length. Afterwards, steel collector bars were fitted into the slots.
  • the cathode blocks were placed into an aluminium electrolysis cell.
  • Cathode blocks trimmed to their final dimensions were manufactured according to example 1.
  • 8 pairs of dead-end horizontal holes each of 1 cm diameter were drilled in parallel to the block top face as well as side face starting from the end faces.
  • the first 4 holes of opposing hole pairs were drilled at a distance of 25 mm below the top block surface.
  • the next pairs each had an axial distance of 50 mm to the respective pair above. All holes were 400 mm deep and the holes of a pair were positioned right and left of he horizontal middle of the block each at a distance of 250 mm from the respective block side face.

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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)
  • Investigating And Analyzing Materials By Characteristic Methods (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
EP03026223A 2003-11-14 2003-11-14 Blocs cathodiques avec dispositif de détection d'usure pour l'électrolyse de l'aluminium Withdrawn EP1531194A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP03026223A EP1531194A1 (fr) 2003-11-14 2003-11-14 Blocs cathodiques avec dispositif de détection d'usure pour l'électrolyse de l'aluminium
JP2004325845A JP4755409B2 (ja) 2003-11-14 2004-11-10 消耗検出機構を備えるアルミニウム電解槽のための陰極ブロック
BRPI0405016 BRPI0405016A (pt) 2003-11-14 2004-11-11 Blocos de catodo para célula de eletrólise de alumìnio com mecanismo de detecção de desgaste

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP03026223A EP1531194A1 (fr) 2003-11-14 2003-11-14 Blocs cathodiques avec dispositif de détection d'usure pour l'électrolyse de l'aluminium

Publications (1)

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EP1531194A1 true EP1531194A1 (fr) 2005-05-18

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EP03026223A Withdrawn EP1531194A1 (fr) 2003-11-14 2003-11-14 Blocs cathodiques avec dispositif de détection d'usure pour l'électrolyse de l'aluminium

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EP (1) EP1531194A1 (fr)
JP (1) JP4755409B2 (fr)
BR (1) BRPI0405016A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2294404C1 (ru) * 2005-09-20 2007-02-27 Открытое акционерное общество "Сибирский научно-исследовательский, конструкторский и проектный институт алюминиевой и электродной промышленности" (ОАО "СибВАМИ") Катодное устройство алюминиевого электролизера
CN101705505B (zh) * 2009-11-18 2011-12-07 中国铝业股份有限公司 一种阴极炭块给料装置
CN101724857B (zh) * 2008-10-13 2013-03-27 高德金 一种阴极碳块钢棒组
WO2013068558A3 (fr) * 2011-11-11 2013-08-22 Sgl Carbon Se Procédé de mesure de profils de surface lors de la finition de cellules d'électrolyse en aluminium
CN112986527A (zh) * 2021-01-29 2021-06-18 山东理工大学 一种表征双辊铸轧过程中熔池内传输行为的方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE500356T1 (de) * 2006-04-13 2011-03-15 Sgl Carbon Se Kathode zur aluminiumelektrolyse mit nicht ebenen rilledesign
CN103820814A (zh) * 2014-03-07 2014-05-28 新疆生产建设兵团农八师天山铝业有限公司 一种阴极炭块钢棒组结构

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3257307A (en) * 1962-06-11 1966-06-21 Kaiser Aluminium Chem Corp Electrolytic cell for the production of aluminum
US5961811A (en) * 1997-10-02 1999-10-05 Emec Consultants Potlining to enhance cell performance in aluminum production
EP1344846A1 (fr) * 2002-03-12 2003-09-17 VAW Aluminium-Technologie GmbH Matériau réfractaire pour cuve d'électrolyse d'aluminium et procédé de fabrication de matériau carbocéramique

Family Cites Families (4)

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CA1277854C (fr) * 1985-05-23 1990-12-18 Alan J. Messenger Detection d'usure
FR2789093B1 (fr) * 1999-02-02 2001-03-09 Carbone Savoie Cathode graphite pour l'electrolyse de l'aluminium
JP4195539B2 (ja) * 2000-04-11 2008-12-10 新日本製鐵株式会社 高炉炉底湯流れ検知方法
JP2002129217A (ja) * 2000-10-30 2002-05-09 Nippon Steel Corp 炉頂旋回駆動装置の損傷度測定方法および保持器

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3257307A (en) * 1962-06-11 1966-06-21 Kaiser Aluminium Chem Corp Electrolytic cell for the production of aluminum
US5961811A (en) * 1997-10-02 1999-10-05 Emec Consultants Potlining to enhance cell performance in aluminum production
EP1344846A1 (fr) * 2002-03-12 2003-09-17 VAW Aluminium-Technologie GmbH Matériau réfractaire pour cuve d'électrolyse d'aluminium et procédé de fabrication de matériau carbocéramique

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE COMPENDEX [online] ENGINEERING INFORMATION, INC., NEW YORK, NY, US; HILTMANN FRANK ET AL: "Laboratory test method for measuring wear rates of carbon cathode materials", XP002284665, Database accession no. E2004128063385 *
LIGHT METALS 2003: PROCEEDINGS OF THE TECHNICAL SESSIONS PRESENTED BY THE TMS ALUMINIUM COMMITTEE AT THE 132ND TMS ANNUAL MEETINGS;SAN DIEGO, CA, UNITED STATES MAR 2-6 2003, 2003, TMS Light Met.;TMS Light Metals 2003, pages 655 - 659 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2294404C1 (ru) * 2005-09-20 2007-02-27 Открытое акционерное общество "Сибирский научно-исследовательский, конструкторский и проектный институт алюминиевой и электродной промышленности" (ОАО "СибВАМИ") Катодное устройство алюминиевого электролизера
CN101724857B (zh) * 2008-10-13 2013-03-27 高德金 一种阴极碳块钢棒组
CN101705505B (zh) * 2009-11-18 2011-12-07 中国铝业股份有限公司 一种阴极炭块给料装置
WO2013068558A3 (fr) * 2011-11-11 2013-08-22 Sgl Carbon Se Procédé de mesure de profils de surface lors de la finition de cellules d'électrolyse en aluminium
RU2576514C2 (ru) * 2011-11-11 2016-03-10 Сгл Карбон Се Способ измерения профилей поверхностей в работающих алюминиевых электролизерах
CN112986527A (zh) * 2021-01-29 2021-06-18 山东理工大学 一种表征双辊铸轧过程中熔池内传输行为的方法
CN112986527B (zh) * 2021-01-29 2023-10-10 山东理工大学 一种表征双辊铸轧过程中熔池内传输行为的方法

Also Published As

Publication number Publication date
BRPI0405016A (pt) 2005-08-30
JP4755409B2 (ja) 2011-08-24
JP2005146417A (ja) 2005-06-09

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