EP0716165A1 - Verfahren und Vorrichtung zum Messen der Temperatur und Badhöhe des geschmolzenen Elektrolyts in Aluminium-Schmelzflussöfen - Google Patents

Verfahren und Vorrichtung zum Messen der Temperatur und Badhöhe des geschmolzenen Elektrolyts in Aluminium-Schmelzflussöfen Download PDF

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Publication number
EP0716165A1
EP0716165A1 EP95420354A EP95420354A EP0716165A1 EP 0716165 A1 EP0716165 A1 EP 0716165A1 EP 95420354 A EP95420354 A EP 95420354A EP 95420354 A EP95420354 A EP 95420354A EP 0716165 A1 EP0716165 A1 EP 0716165A1
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EP
European Patent Office
Prior art keywords
electrolyte
probe
level
temperature
measuring
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.)
Granted
Application number
EP95420354A
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English (en)
French (fr)
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EP0716165B1 (de
Inventor
Benoît SULMONT
Pierre Homsi
Olivier Granacher
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 France SAS
Original Assignee
Aluminium Pechiney SA
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Publication date
Application filed by Aluminium Pechiney SA filed Critical Aluminium Pechiney SA
Publication of EP0716165A1 publication Critical patent/EP0716165A1/de
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Publication of EP0716165B1 publication Critical patent/EP0716165B1/de
Anticipated expiration legal-status Critical
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    • 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
    • C25C3/20—Automatic control or regulation of cells

Definitions

  • the invention relates to the temperature and level measurements of the electrolyte based on molten cryolite in aluminum production tanks by electrolysis of alumina dissolved in said cryolite as well as the application to the determination of the thickness. of the electrolysis bath melted in these same cells.
  • the volume of the electrolyte covering the layer of liquid aluminum in contact with the cathode at the bottom of the tank, or cathode substrate, must be sufficient to ensure dissolution and rapid distribution of the alumina which is introduced into the upper part of tank. However, it must not exceed a certain level beyond which it would disturb the thermal equilibrium of the tank and would cause corrosion of the steel logs to which the anodes are fixed and consequently pollution by iron of the aluminum produced or metal.
  • knowing and monitoring the temperature of the electrolyte is very important, on the one hand in order to properly regulate the operation of the tank in permanent operating mode corresponding to a thermal equilibrium between the power supplied and the power dissipated, on the other hand to optimize the electrolysis process, in particular the Faraday yield, knowing that a simple increase in the bath temperature of ten degrees celsius can lower the Faraday yield by 1 to 2%, while conversely a lowering the electrolyte temperature by ten degrees celsius can reduce the already low solubility of alumina in the cryolite in the temperature zone considered (around 950 ° C) and promote the "anode effect", that is to say the anode polarization, with sudden rise in the voltage across the terminals of the tank and release in large quantity of fluorinated products from the decomposition of the electrolyte.
  • the prior art even recent, provides only very incomplete solutions to these problems by completely neglecting the temperature measurement aspect and by recommending, for the measurements of level or thickness of the electrolyte, methods of which the accuracy remains questionable and also implies having an individual adjustment of the anode level on the tanks.
  • the document EP 0195143 describes a method for measuring the level of the electrolyte in an electrolytic cell according to which one of the anodes through which a given current is progressively raised, the decrease in current is measured as a function of the increase in the interpolar distance, therefore of the lifting height and the height for which the current has dropped to a predetermined fraction of its initial value is noted. After calibration, the electrolyte level can be deduced. For this we add to the distance traveled by the anode, the initial interpolar distance and a geometric correction term.
  • this method supposes a very great homogeneity of the electrolyte, but its resistivity varies locally and over time with its composition and in particular with the content of dissolved alumina. Furthermore, this method requires significant movements of the anode which can disrupt the operation of the tank when this operation is too often repeated.
  • the document EP 0288397 describes a process for controlling the additions of solidified bath in an electrolysis tank which consists in periodically determining the thickness of the electrolyte HB which is compared with a reference value HC and then adjusted accordingly.
  • HB it is necessary in an intermediate step to measure the level of the bath relative to a fixed mark and this measurement is carried out by means of a probe associated with a level sensor and equipped with a pointerolle electrically connected to the cathode of the electrolytic cell.
  • a probe associated with a level sensor and equipped with a pointerolle electrically connected to the cathode of the electrolytic cell.
  • the invention also relates to the device suitable for implementing the method, namely the stitching and measurement device intended to measure, after piercing the surface crust of solidified bath, the temperature and the level of the electrolyte in a production tank.
  • the device integral but electrically isolated from the superstructure comprising stitching means, or stitching, of the crust, being characterized in that it is provided with measuring means of the temperature and of the level of the electrolyte constituted mainly by a cylindrical probe moving vertically along its major axis inside the tapping means by automatically carrying out, according to a determined operating sequence, the periodic control of this temperature and of this level, and that said stitching means also ensure the removal of the deposit of solidified bath on the measurement probe.
  • the invention constitutes another improvement of the method according to EP 0288397 already analyzed in the prior art of the application.
  • thermocouple probes continuously immersed in the electrolyte due to its very high aggressiveness, but also the need to increase the frequency of temperature controls performed manually at the same time as the measurement of the level of the electrolyte, has led the applicant to study and develop an automatic method for measuring temperature and level of the electrolyte with a device suitable for its implementation after having found that the temperature measurement at frequency high and with good accuracy is possible by intermittent immersion of a probe thermocouple in the electrolyte for a relatively short time not requiring the thermal equilibrium of the probe with the electrolyte to be obtained as soon as its end of temperature rise can be correctly extrapolated.
  • the total duration of immersion of the probe in the electrolyte is between 30 seconds and 30 minutes without its temperature generally exceeding 940 ° C. .
  • thermocouple probes of the same type continuously immersed in the electrolyte. until destroyed and near the orifice of the intermittent immersion probe.
  • the method according to the invention is not linked to a particular method of extrapolation of the equilibrium temperature. It also includes any method aiming to predetermine the equilibrium temperature of the probe from a time of maintaining the probe in immersion which is less than the actual time of equilibration of the temperature of the probe with that of the electrolyte.
  • the relatively high frequency of temperature measurements preferably every 30 minutes to 48 hours, with the possibility of selecting and canceling abnormal, or even simply questionable, measurements when they were carried out during periodic ad hoc operations which temporarily modify the equilibrium state of the tank, contributes to increasing the reliability of the process of driving the tanks.
  • This selection is made by the control and regulation system of the tank connected to the computer which authorizes, after a clearance of the probe passage orifice and the removal by scraping of the solidified bath deposit, the implementation of the measurement of the electrolyte level by immersion of the pointerolle connected on the one hand to a displacement sensor and on the other hand to the cathode substrate, whose potential difference compared to said substrate increases suddenly when the pointerolle comes into contact with the electrolyte.
  • the sensor acquires 2 position / potential signals for each measurement which it transforms into electrolyte level with respect to a reference point expressed in mm. These level values are then transmitted to the control and regulation system of the tank to determine the average level of the electrolyte after elimination of doubtful or aberrant measurements.
  • the stitching and measuring device 1 is intended to measure, after piercing the crust 2 of the solidified bath, the temperature and the level of the electrolyte 3 in contact with the carbon anodes 4 and above the sheet of liquid aluminum or metal. 5 resting on the cathode substrate 6. It is integral but electrically insulated from the superstructure 7 of the tank and comprises stitching means 8 formed at their lower part by a hollow cylindrical pricker 9 actuated by at least one jack 10 driven by a vertical translational movement for piercing and then maintaining in the crust a passage orifice making it possible to use means 11 for measuring the temperature and the electrolyte level constituted mainly by a cylindrical probe 12.
  • the pricker 9 ensures at the same time, by scraping, the removal of the deposit 18 of solidified bath on the external surface of said probe.
  • the clearance between the prick 9 and the probe 12, according to fig. 2a and fig. 2b, must be sufficient (0.5 to 20 mm in radius) to allow their relative displacement without friction but must not be too large to avoid the progressive formation of an excessive deposit of solidified bath on the lower part of the probe 12.
  • a potentiometer 14 makes it possible to determine with precision the position of the probe in height then that simultaneously a voltmeter 15 measures the potential difference between the probe 12 and the cathode substrate 6.
  • the probe 12 consists of an external cylindrical sheath 22, for example made of stainless steel, 100 to 600 mm in length, 7 to 100 mm in outside diameter and the wall thickness of which does not exceed 40 mm and is preferably between 2 and 10 mm to reduce heat losses.
  • a thermocouple 21 in its sheath 19. This thermocouple is electrically connected at its upper part to the control and regulation system 17, which by extrapolation of the temperature of the probe determines the temperature of the electrolyte.
  • FIGS. 3a, 3b, 3c and 3d Several variants of the stitching device have been studied and are shown in FIGS. 3a, 3b, 3c and 3d which cannot however be considered as a limitation of the invention to these configurations only.
  • the measuring cylinder with a through rod for displacing the probe 12 has been replaced by a simple cylinder which makes it possible to reduce the height of the stitching and measuring device and to increase the power of the movement of the measurement.
  • the duration of immersion of the probe in the electrolyte corresponds to the time of acquisition by the probe of at least the temperature of 850 ° C. and preferably 920 °. C, plus the time necessary to obtain, from this temperature, a very low temperature for heating the probe, for example less than 3 ° C / second.
  • the probe When this threshold is reached, the probe is raised to its initial position and the successive values of temperature measured by the thermocouple 21 are transmitted to the command and regulation system 17 which determines, by extrapolation from the N different pairs of values (ti , Ti) temperature / time, the temperature Tb of the electrolyte.
  • the safety nozzle 9 is actuated downhill to ensure cleaning and the passage of probe 12, then its ascent which authorizes the engagement of the electrolyte level measurement sequence. .
  • the method and the device according to the invention can also be adapted to the measurement the level of the electrolyte / metal interface.
  • a new variation in potential between the cathode substrate and the pin of the probe when it passes through the electrolyte / metal interface can be recorded by depressing the probe into the metal sheet. This variation results in a large decrease in potential probe-metal / cathode difference compared to the potential difference probe-electrolyte / cathode previously recorded due to the significant decrease in resistance of the new medium.

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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)
EP95420354A 1994-12-09 1995-12-07 Verfahren und Vorrichtung zum Messen der Temperatur und Badhöhe des geschmolzenen Elektrolyts in Aluminium-Schmelzflussöfen Expired - Lifetime EP0716165B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9415086A FR2727985B1 (fr) 1994-12-09 1994-12-09 Procede et dispositif de mesure de la temperature et du niveau du bain d'electrolyse fondu dans les cuves de production d'aluminium
FR9415086 1994-12-09

Publications (2)

Publication Number Publication Date
EP0716165A1 true EP0716165A1 (de) 1996-06-12
EP0716165B1 EP0716165B1 (de) 1998-07-08

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EP95420354A Expired - Lifetime EP0716165B1 (de) 1994-12-09 1995-12-07 Verfahren und Vorrichtung zum Messen der Temperatur und Badhöhe des geschmolzenen Elektrolyts in Aluminium-Schmelzflussöfen

Country Status (7)

Country Link
US (1) US6065867A (de)
EP (1) EP0716165B1 (de)
AU (1) AU689973B2 (de)
CA (1) CA2164687C (de)
DE (1) DE69503342T2 (de)
FR (1) FR2727985B1 (de)
NO (1) NO312554B1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008002834A2 (en) * 2006-06-27 2008-01-03 Alcoa Inc. Systems and methods useful in controlling operations of metal electrolysis cells
US7726900B2 (en) 2003-11-18 2010-06-01 E.C.L. System for connecting two shafts in translation
CN104233374A (zh) * 2013-06-07 2014-12-24 攀钢集团钛业有限责任公司 镁电解槽液位检测装置和方法以及镁电解槽
FR3077018A1 (fr) * 2018-01-24 2019-07-26 Rio Tinto Alcan International Limited Dispositif de percage comprenant un fourreau tubulaire fixe a un verin

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE511376C2 (sv) * 1997-11-28 1999-09-20 Sintercast Ab Provtagningsanordning för termisk analys av stelnande metall
DE19909614C1 (de) * 1999-03-05 2000-08-03 Heraeus Electro Nite Int Eintauchsensor, Meßanordnung und Meßverfahren zur Überwachung von Aluminium-Elektrolysezellen
DE10331124B3 (de) * 2003-07-09 2005-02-17 Heraeus Electro-Nite International N.V. Verfahren und Vorrichtung zum Messen der Abkühlkurve von Schmelzenproben und/oder der Aufheizkurve von Schmelzenproben sowie deren Verwendung
US6942381B2 (en) * 2003-09-25 2005-09-13 Alcoa Inc. Molten cryolitic bath probe
FR2872176B1 (fr) * 2004-06-25 2006-07-28 Ecl Soc Par Actions Simplifiee Racleur d'un organe de percage d'une croute de bain d'une cellule d'electrolyse destinee a la production d'aluminium
US7275429B2 (en) * 2005-04-06 2007-10-02 Itt Manufacturing Enterprises Inc. Mechanical self-cleaning probe via bi-metallic or shape memory
CN101270485B (zh) * 2008-05-10 2010-06-16 中国铝业股份有限公司 电解过热度控制方法
DE102008025090A1 (de) 2008-05-26 2009-12-17 Robert Bosch Gmbh Vorrichtung zum Messen der Temperatur eines Bades in einem Reduktionsbecken
AU2015203272B2 (en) * 2009-03-26 2016-06-30 Alcoa Usa Corp. System, method and apparatus for measuring electrolysis cell operating conditions and communicating the same
US8409409B2 (en) * 2009-03-26 2013-04-02 Alcoa Inc. System, method and apparatus for measuring electrolysis cell operating conditions and communicating the same
CN102703934B (zh) * 2012-06-08 2015-05-20 云南铝业股份有限公司 一种提高铝电解槽焙烧温度均匀性的方法
CN104480495B (zh) * 2014-12-17 2016-09-28 湖南创元铝业有限公司 铝电解槽单槽出铝量控制方法
CN106555211B (zh) * 2015-09-25 2018-11-27 沈阳铝镁设计研究院有限公司 一种铝电解槽阴极压降的测量工具及测量方法
CN106768167B (zh) * 2016-11-15 2019-02-15 北京科技大学 一种基于阻抗变化的电解槽液位在线自主测量系统及方法
CN107164784B (zh) * 2017-06-29 2023-06-30 山东宏桥新型材料有限公司 一种自动间断式检测铝电解质温度的系统
KR101892732B1 (ko) * 2017-10-17 2018-08-28 한국원자력연구원 다접점 온도센서를 이용한 광대역 용융금속 액위 측정 장치 및 열 시스템
CN110501080B (zh) * 2019-09-06 2024-02-13 中冶赛迪信息技术(重庆)有限公司 铝槽熔池探测器、探测装置及方法
CN112665642B (zh) * 2020-12-02 2023-02-10 沈阳铝镁设计研究院有限公司 铝电解槽电解质温度、两水平和炉底压降在线测量系统

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FR2104781A1 (en) * 1970-07-13 1972-04-21 Union Carbide Corp Thermocouple sheath - for use in al-electrolysis cell
SU929747A1 (ru) * 1977-10-10 1982-05-23 за вители ЙП;Ог аз,, 5 ATiiHVKy, n-KJ| ;KMS-« . BKiijfSaiEjiA Способ контрол технологического состо ни алюминиевого электролизера
SU1236003A1 (ru) * 1984-12-27 1986-06-07 Красноярский Политехнический Институт Способ контрол температуры электролита алюминиевого электролизера
EP0288397A1 (de) * 1987-04-21 1988-10-26 Aluminium Pechiney Verfahren und Vorrichtung zur Kontrolle von Festelektrolytzuführungen in Elektrolyseöfen für die Aluminiumherstellung

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Publication number Priority date Publication date Assignee Title
FR2104781A1 (en) * 1970-07-13 1972-04-21 Union Carbide Corp Thermocouple sheath - for use in al-electrolysis cell
SU929747A1 (ru) * 1977-10-10 1982-05-23 за вители ЙП;Ог аз,, 5 ATiiHVKy, n-KJ| ;KMS-« . BKiijfSaiEjiA Способ контрол технологического состо ни алюминиевого электролизера
SU1236003A1 (ru) * 1984-12-27 1986-06-07 Красноярский Политехнический Институт Способ контрол температуры электролита алюминиевого электролизера
EP0288397A1 (de) * 1987-04-21 1988-10-26 Aluminium Pechiney Verfahren und Vorrichtung zur Kontrolle von Festelektrolytzuführungen in Elektrolyseöfen für die Aluminiumherstellung

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Title
CHEMICAL ABSTRACTS, vol. 97, no. 14, 4 October 1982, Columbus, Ohio, US; abstract no. 117484, DUDAREV G. A.: "MONITORING THE PROCESSING STATE OF AN ALUMINIUM ELECTROLYTIC CELL BY IMMERSING A METALLIC PROBE INTO AN ELECTROLYTE MELT" page 501; column GAUCHE; *
DATABASE WPI Derwent World Patents Index; AN 87-020961, "ALUMINIUM REDN. CELL ELECTROLYTE TEMP. MONITORING-BY SIMULTANEOUSLY MEASURING CELL VOLTAGE AND CURRENT IN GIVEN FREQUENCY RANGE TO APPLY FORMULA WITH REGRESSION COEFFICIENTS." *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7726900B2 (en) 2003-11-18 2010-06-01 E.C.L. System for connecting two shafts in translation
WO2008002834A2 (en) * 2006-06-27 2008-01-03 Alcoa Inc. Systems and methods useful in controlling operations of metal electrolysis cells
WO2008002834A3 (en) * 2006-06-27 2008-09-25 Alcoa Inc Systems and methods useful in controlling operations of metal electrolysis cells
CN102747386A (zh) * 2006-06-27 2012-10-24 美铝公司 用于控制金属电解单元的操作的系统和方法
CN104233374A (zh) * 2013-06-07 2014-12-24 攀钢集团钛业有限责任公司 镁电解槽液位检测装置和方法以及镁电解槽
FR3077018A1 (fr) * 2018-01-24 2019-07-26 Rio Tinto Alcan International Limited Dispositif de percage comprenant un fourreau tubulaire fixe a un verin

Also Published As

Publication number Publication date
DE69503342D1 (de) 1998-08-13
CA2164687A1 (fr) 1996-06-10
CA2164687C (fr) 2005-02-15
FR2727985A1 (fr) 1996-06-14
AU689973B2 (en) 1998-04-09
NO312554B1 (no) 2002-05-27
FR2727985B1 (fr) 1997-01-24
NO954740L (no) 1996-06-10
AU3901895A (en) 1996-06-20
US6065867A (en) 2000-05-23
NO954740D0 (no) 1995-11-23
DE69503342T2 (de) 1999-03-04
EP0716165B1 (de) 1998-07-08

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