EP0455590A1 - Régulation et stabilisation de la teneur en A1F3 d'une cave d'électrolyse de l'aluminium - Google Patents

Régulation et stabilisation de la teneur en A1F3 d'une cave d'électrolyse de l'aluminium

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Publication number
EP0455590A1
EP0455590A1 EP91810305A EP91810305A EP0455590A1 EP 0455590 A1 EP0455590 A1 EP 0455590A1 EP 91810305 A EP91810305 A EP 91810305A EP 91810305 A EP91810305 A EP 91810305A EP 0455590 A1 EP0455590 A1 EP 0455590A1
Authority
EP
European Patent Office
Prior art keywords
alf3
content
days
aluminum
addition
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
EP91810305A
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German (de)
English (en)
Other versions
EP0455590B1 (fr
Inventor
Peter Entner
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.)
3A Composites International AG
Original Assignee
Alusuisse Lonza Services Ltd
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 Lonza Services Ltd filed Critical Alusuisse Lonza Services Ltd
Publication of EP0455590A1 publication Critical patent/EP0455590A1/fr
Application granted granted Critical
Publication of EP0455590B1 publication Critical patent/EP0455590B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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 a method for regulating and stabilizing an at least 10 wt .-% AlF3 content in the bath of an electrolysis cell for the production of aluminum from aluminum oxide dissolved in a cryolite melt.
  • a bath or an electrolyte which essentially consists of cryolite, a sodium aluminum fluorine compound (3NaF.AlF3).
  • This cryolite in addition to the aluminum oxide to be dissolved, in particular also has substances which lower the melting point, for example aluminum trifluoride AlF3, lithium fluoride LiF, calcium difluoride CaF2 and / or magnesium difluoride MgF2.
  • a bath in an electrolysis cell for the production of aluminum contains 6 to 8 wt.% AlF3, 4 to 6 wt.% CaF2, 1 to 2 wt.% LiF, the rest cryolite.
  • the melting point of the bath is lowered in the range of 940 to 970 ° C, the industrial temperature range.
  • bath additives do not only have positive effects, e.g. a lowering of the melting point, but often also have a negative effect.
  • the addition of lithium fluoride, for example, does not allow film qualities for capacitors without special metal treatment.
  • the inventor has set itself the task of creating a method of the type mentioned, with which the fluctuations in the AlF3 content and thus the bath temperature can be brought to a small standard deviation even without lithium fluoride additives, for the AlF3 content to about 1 up to 2%.
  • Counteractive additives with neutralizing Effects, such as soda or sodium fluoride, should not be used or should only be used in exceptional cases.
  • the object is achieved in that the individual condition of an aluminum electrolysis cell, in particular of its cathodic carbon trough, is analyzed during a period t 1 from a series of measured values comprising a plurality of parameters, with a model calculation the optimal time difference between the addition of AlF 3 and its effect in the electrolyte determined, the additions of AlF3 calculated by specifying a certain AlF3 content in consideration of the time difference and AlF3 is added in portions or continuously.
  • AlF3 During the aluminum electrolysis there is always a loss of AlF3, on the one hand by evaporation, which does not or only to a very limited extent affect the environment in encapsulated aluminum electrolysis cells, and on the other hand by reaction with Na2O contained in the added alumina.
  • AlF3 there are tables listing the units to be added depending on the bath temperature and the AlF3 content to be set. These tables can be refined by using general correction factors such as Cell age, number of anode effects, trend of concentration are taken into account.
  • the measurement and analysis of the individual state of aluminum electrolysis and the determination of the optimal time shift are not only carried out separately for each cell, but also at different intervals if necessary. In the case of healthy, normally working cells, this is preferably done every 1 to 2 months, in the case of poor oven operation, repeated 1 to 5 days apart from the program until the oven operation improves and the intervals can be extended again. Thanks to the individual, up-to-date recording of the cell status, general tables can be made which do not indicate the cell type or its type Take into account condition, be waived.
  • the measurement of the AlF3 content can be replaced by a temperature measurement. This is not only easier, but inevitably records a temperature dependency of the AlF3 content and can be used directly.
  • the most important parameters for the model calculation used according to the invention are the flux mass M and the daily AlF3 losses v. These parameters are calculated from measurements of the concentration c and the additions z of AlF3 in the electrolyte over a period t1 of preferably 10 to 60 days, in particular 20 to 30 days.
  • the period t 1 is so short on the one hand that the individual condition of a cell can currently be recorded, but on the other hand so long that accidental, short-term changes without trend are disregarded.
  • the calculated flux mass M and daily AlF3 losses v are included in the model calculation and calculated with time shifts ZV of preferably 1 to 10 whole days.
  • the best set of parameters is selected according to known statistical criteria and the addition z of AlF3 is calculated by specifying an AlF3 content c between 10 and 15 wt .-%.
  • the specification for the AlF3 content c depends on the electrolysis temperature considered optimal. This can be obtained, for example, with about 12% by weight aluminum fluoride.
  • the best parameter set containing the time shift ZV is used for the addition of z of aluminum fluoride for the next n days.
  • M the flux mass
  • c s the target value for the AlF3 content
  • c m the instantaneous value for the AlF3 content
  • v the daily AlF3 loss.
  • the period of n days should generally not be greater than the period t 1 during which the basics for determining the parameters were measured.
  • the time period is corrected by the time difference ZV.
  • a modified formula can be used to predict how high the aluminum fluoride content c x should be on the day t x according to the model calculation.
  • the model can be checked for suitability by a measurement on the relevant day t x and adjusted if necessary.
  • Soda is preferably added according to the formula
  • intraday values can also be entered. Because that was determined with the model calculation optimal time shift ZV for the addition of aluminum fluoride in electrolysis cells used in the aluminum industry is generally in the range of 2 to 5 days, in particular 3 days, according to a further developed embodiment of the invention, intraday time shifts ZV lying in this period are calculated and to determine the best parameter set listed.
  • the rough grid for the time shift ZV can be brought down to the fineness required in practice by the introduction of a decimal place.
  • the aluminum fluoride is conventionally introduced in sacks, more modern cells work with dosing devices, and increasingly also the dense phase conveyance is used.
  • the metering devices or devices are preferably controlled by a process computer and release the aluminum fluoride in portions or continuously.
  • the fluctuations in the AlF3 concentration in the electrolyte can be reduced to a standard deviation of 1 to 2%, which in a concentration range of 10 to 15% by weight of aluminum fluoride leads to simplified process control and a well-known increase in the production of aluminum. Excessive target values can be prevented, as can the addition of an antidote such as soda or sodium fluoride. Electrolyte additives, such as lithium fluoride, which have a detrimental effect in certain uses, are not necessary.
  • the measurement variables and their units of measurement defined in connection with the present invention are the following: c: AlF3 content in the electrolyte (% by weight) t1: period (days) z: AlF3 addition (kg / day ZV: time difference (days) M: flow mass (kg) v: AlF3 losses (kg / day) z s : Soda addition (kg / day n: days c s : setpoint AlF3 content (% by weight)
  • Fig. 1 the typical time course of the AlF3 concentration (wt .-%) with the corresponding AlF3 additions in kg / day is given.
  • Table II shows the calculation of the optimal addition for stabilizing the AlF3 concentration.
  • Fig. 2 the time course of the AlF3 concentration (wt .-%) corresponding to Fig. 1 after using the model calculations (from January) is shown. You can see the much improved temporal stability of the values.

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)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
EP91810305A 1990-05-04 1991-04-24 Régulation et stabilisation de la teneur en A1F3 d'une cave d'électrolyse de l'aluminium Expired - Lifetime EP0455590B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH152790 1990-05-04
CH1527/90 1990-05-04

Publications (2)

Publication Number Publication Date
EP0455590A1 true EP0455590A1 (fr) 1991-11-06
EP0455590B1 EP0455590B1 (fr) 1995-06-28

Family

ID=4212527

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91810305A Expired - Lifetime EP0455590B1 (fr) 1990-05-04 1991-04-24 Régulation et stabilisation de la teneur en A1F3 d'une cave d'électrolyse de l'aluminium

Country Status (9)

Country Link
US (1) US5094728A (fr)
EP (1) EP0455590B1 (fr)
AU (1) AU643006B2 (fr)
CA (1) CA2041440A1 (fr)
DE (1) DE59105830D1 (fr)
ES (1) ES2075401T3 (fr)
IS (1) IS1632B (fr)
NO (1) NO304748B1 (fr)
ZA (1) ZA913260B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2774701A1 (fr) * 1998-02-12 1999-08-13 Heraeus Electro Nite Int Procede pour reguler la teneur en alf3 de masses fondues de cryolithe
EP1344847A1 (fr) * 2001-12-03 2003-09-17 Alcan Technology & Management AG Régulation d'une cave d'électrolyse de l'aluminium

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2821363B1 (fr) * 2001-02-28 2003-04-25 Pechiney Aluminium Procede de regulation d'une cellule d'electrolyse
FR2821364B1 (fr) * 2001-02-28 2004-04-09 Pechiney Aluminium Procede de regulation d'une cellule d'electrolyse
RU2284377C2 (ru) * 2004-01-05 2006-09-27 Открытое акционерное общество "Сибирский научно-исследовательский, конструкторский и проектный институт алюминиевой и электродной промышленности" (ОАО "СибВАМИ") Способ отбора проб электролита из электролизера для производства алюминия
WO2014165203A1 (fr) * 2013-03-13 2014-10-09 Alcoa Inc. Systèmes et procédés permettant de protéger les parois latérales de cellule d'électrolyse
CN104451779B (zh) * 2014-12-17 2017-01-18 湖南创元铝业有限公司 铝电解槽氟化铝控制方法
WO2020190271A1 (fr) * 2019-03-16 2020-09-24 General Electric Company Système et procédé de commande de conduite de creuset de fusion
CN117133366B (zh) * 2023-08-28 2026-01-02 中国铝业股份有限公司 一种铝电解槽中氟化铝添加量的计算方法
CN117210879B (zh) * 2023-10-12 2025-02-11 中国铝业股份有限公司 一种铝电解槽用氟化铝添加量计算方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0195142A1 (fr) * 1985-03-18 1986-09-24 Alcan International Limited Procédé pour réguler l'addition de AlF3 à l'électrolyte d'une cuve d'électrolyse pour la production d'aluminium
FR2620738A1 (fr) * 1987-09-18 1989-03-24 Pechiney Aluminium Procede de regulation de l'acidite du bain d'electrolyse par recyclage des produits fluores emis par les cuves d'electrolyse hall-heroult

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3380897A (en) * 1964-11-16 1968-04-30 Reynolds Metals Co Method of determining ore concentration
US3471390A (en) * 1965-03-24 1969-10-07 Reynolds Metals Co Alumina concentration meter
NO166821C (no) * 1985-02-21 1991-09-04 Aardal & Sunndal Verk As Fremgangsmaate for styring av aluminiumoksyd-tilfoerselen til elektrolyseovner for fremstilling av aluminium.
FR2581660B1 (fr) * 1985-05-07 1987-06-05 Pechiney Aluminium Procede de regulation precise d'une faible teneur en alumine dans une cuve d'electrolyse ignee pour la production d'aluminium
US4654130A (en) * 1986-05-15 1987-03-31 Reynolds Metals Company Method for improved alumina control in aluminum electrolytic cells employing point feeders
US4814050A (en) * 1986-10-06 1989-03-21 Aluminum Company Of America Estimation and control of alumina concentration in hall cells

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0195142A1 (fr) * 1985-03-18 1986-09-24 Alcan International Limited Procédé pour réguler l'addition de AlF3 à l'électrolyte d'une cuve d'électrolyse pour la production d'aluminium
FR2620738A1 (fr) * 1987-09-18 1989-03-24 Pechiney Aluminium Procede de regulation de l'acidite du bain d'electrolyse par recyclage des produits fluores emis par les cuves d'electrolyse hall-heroult

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SOVIET INVENTIONS ILLUSTRATED, Woche E34, 6. Oktober 1982, Zusammenfassung Nr. 71690 M28, Sektion Chemical, Derwent Publications Ltd, London, GB; & SU-A-852 975 (ALUM. MAGN. ELECTR. IND.) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2774701A1 (fr) * 1998-02-12 1999-08-13 Heraeus Electro Nite Int Procede pour reguler la teneur en alf3 de masses fondues de cryolithe
WO1999041432A1 (fr) * 1998-02-12 1999-08-19 Heraeus Electro-Nite International N.V. PROCEDE POUR REGULER LA TENEUR EN AlF3 DANS DES BAINS DE CRYOLITE
US6183620B1 (en) 1998-02-12 2001-02-06 Heraeus Electro-Nite International N.V. Process for controlling the A1F3 content in cryolite melts
EP1344847A1 (fr) * 2001-12-03 2003-09-17 Alcan Technology & Management AG Régulation d'une cave d'électrolyse de l'aluminium

Also Published As

Publication number Publication date
IS3698A7 (is) 1991-11-05
EP0455590B1 (fr) 1995-06-28
CA2041440A1 (fr) 1991-11-05
DE59105830D1 (de) 1995-08-03
IS1632B (is) 1996-07-19
AU7601591A (en) 1991-11-07
NO911708D0 (no) 1991-04-30
AU643006B2 (en) 1993-11-04
NO304748B1 (no) 1999-02-08
ES2075401T3 (es) 1995-10-01
US5094728A (en) 1992-03-10
NO911708L (no) 1991-11-05
ZA913260B (en) 1992-01-29

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