EP0288397B1 - Procédé et dispositif de contrôle des additions d'électrolyte solide dans les cuves d'électrolyse pour la production d'aluminium - Google Patents

Procédé et dispositif de contrôle des additions d'électrolyte solide dans les cuves d'électrolyse pour la production d'aluminium Download PDF

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Publication number
EP0288397B1
EP0288397B1 EP88420122A EP88420122A EP0288397B1 EP 0288397 B1 EP0288397 B1 EP 0288397B1 EP 88420122 A EP88420122 A EP 88420122A EP 88420122 A EP88420122 A EP 88420122A EP 0288397 B1 EP0288397 B1 EP 0288397B1
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EP
European Patent Office
Prior art keywords
bath
height
superstructure
distance
cathode substrate
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 - Lifetime
Application number
EP88420122A
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German (de)
English (en)
French (fr)
Other versions
EP0288397A1 (fr
Inventor
Benoît SULMONT
Alain Paternoga
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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Filing date
Publication date
Application filed by Aluminium Pechiney SA filed Critical Aluminium Pechiney SA
Publication of EP0288397A1 publication Critical patent/EP0288397A1/fr
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Publication of EP0288397B1 publication Critical patent/EP0288397B1/fr
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 production of aluminum by electrolysis of alumina dissolved in molten cryolite, according to the Hall-Héroult method, and more precisely a method and a device for controlling the additions of solid electrolyte in the electrolytic cells. .
  • This electrolyte essentially consists of NaolitAlF6 cryolite and can contain various additives such as CaF2, AlF3, LiF, etc ... intended to act on the melting point, on the electrochemical properties and on the ability to dissolve l alumina.
  • the volume of the electrolyte must be sufficient to ensure rapid dissolution and distribution of the alumina introduced into the tank, but it must not exceed a certain level beyond which it would cause corrosion of the steel rods to which are suspended the anodes, with, as a consequence, an increase in the iron content of the aluminum produced and a more frequent change of the corroded steel rods.
  • the operator chooses, to avoid the risk of imbalance by default of bath, to work in slight excess and to correct by regular flows of liquid bath, the word "flow" being taken here in the direction of extraction at l liquid state.
  • the bath additions undergo significant and poorly controlled fluctuations, due in particular to the time that elapses between the addition of ground bath to cover the anodes and its passage in the molten state in the tank. This results in significant variations in the bath heights, and significant handling of the liquid bath, causing damaging variations in the thermal balance of the tanks.
  • the idea underlying the present invention consists in making an indirect measurement of the height of the molten bath layer from the measurement of the total height of the molten metal layer and of the molten bath layer which it overcomes, with respect to the cathode substrate taken as a reference plane and an evaluation of the height of the layer of molten metal, which gives, by difference, the height of the layer of molten bath.
  • the position of the upper face of the cathode substrate (formed by the juxtaposition of carbonaceous cathode blocks) is known precisely by construction, with respect to the other fixed elements of the metal structure comprising the box, the tank superstructure, and the anode frame or the equivalent suspension device - collective or individual or by group - of the anodes.
  • This position can vary during the life of the tank (lifting by swelling of the cathode blocks or their substrate, or on the contrary wear of this surface by erosion) but in any case such effects are extremely slow (variations of the 'order of mm per month), which is not a problem for comparative measurements on the scale of a few days or weeks, periodically readjusted by physical measurement of this basic level.
  • a level reference a fixed point located for example on the rim of the box, on a vertical upright in a horizontal beam of the superstructure, and whose vertical dimension, relative to the carbonaceous cathode substrate, is known so precise. It will suffice to measure the level of the molten bath relative to this fixed dimension point to immediately deduce therefrom the total height HT of the metal layer (HM) and of the molten bath layer (HB).
  • This level measurement can be carried out by different direct devices: electrical contact with the surface of the bath, or indirect: proximity effect, light, radio or ultrasonic telemetry on the surface of the bath, preferably through an orifice made in the solidified electrolyte crust, which in normal operation covers the electrolysis tank.
  • the measurement of the level of the bath in the tank is carried out by establishing an electrical contact between the surface of the bath 3 and a pointerolle 7 movable relative to the fixed superstructure 11, along a vertical axis and connected to the cathode substrate by low value resistance.
  • the object of the invention is to optimize the level of the electrolyte and to keep it very close to the set value, which reduces the risks of corrosion of the anode rods due to an excessive level, and the risks of formation. undissolved alumina sludge on the cathode substrate (if the level is insufficient).
  • an effort will be made, according to the invention, to avoid any significant overshooting of the set value, since an excess of bath is more difficult to correct than a defect and the consequences of an excess are in principle more troublesome and more damaging than those of a defect.
  • the total value of the electrolysis bath of a series represents a significant capital asset and it is desirable to reduce it as much as possible.
  • the level of the bath tends to increase constantly, and it is frequent that one has to pour several tens of kilos of bath per ton of aluminum produced. As this operation is relatively awkward, it is only practiced when the setpoint level has been exceeded by several centimeters (4 to 5 for example). According to the invention, it is possible to maintain the fluctuations around the setpoint at approximately plus or minus one centimeter, so that, for the same setpoint, the average level of the bath according to the invention, over a long period, is below the average level of the bath according to the prior art.
  • FIG. 1 appear, from bottom to top: the cathode substrate 1 on which the sheet 2 of liquid aluminum is formed, surmounted by the electrolysis bath 3, based on cryolite in which the anode 4 is immersed.
  • a frozen electrolyte crust 5 covers the electrolysis bath 3, at a very short distance, over the entire free surface, around the anodes and up to the lateral slopes, with the exception of a certain number of orifices 6 which is kept open permanently, under the action of biting cylinders to ensure the evacuation of the gases produced by the electrolysis and allow the introduction of alumina and various additives, during the electrolysis.
  • the chisel 7, disposed at the end of a rod 8, can move along a substantially vertical axis under the action of the jack 9 associated with a displacement sensor 10.
  • This device is subject to the superstructure 11 of the tank which constitutes a fixed reference level.
  • the punch 7 must be electrically isolated from the superstructure.
  • a rubbing electrical contact 12 cooperates with the movable rod 8. It is connected via a resistor 13 of low value (of the order of 1 k ⁇ for example) to a socket 14 in the cathode substrate.
  • the chisel being raised to the maximum level, it is lowered gradually, while measuring the potential difference across the resistance 13.
  • This ddp is practically equal to 0 at the origin.
  • the displacement sensor 10 displays the stroke of the chisel in its downward movement.
  • the stroke of the pointerolle at this moment, that is to say D3.
  • This HB value is introduced, in a known manner, into the computer which prepares the orders for adding ground bath, as a function of the difference between HB measured and the HBC setpoint.
  • This method and this HB measurement device have the advantage of being simple to implement and, above all, of causing only brief contact between the molten bath and the chisel, which is raised from the acquisition of the D3 value, and whose lifespan, is therefore very long.
  • Another advantage is that this measurement makes it possible to verify that the supply orifice 6 is properly unblocked: an outlier of the voltage across the resistor 13, or the impossibility of acquiring this value, can trigger an alarm and / or a device for unblocking the hole (picker controlled by a jack).
  • the fact that we stop the descent of the chisel 7 as soon as it is in contact with the liquid bath saves supply air for cylinder 9.
  • Figure 2 appears the hopper 15 containing the ground bath, which is associated with one of the distributors 16 of alumina.
  • FIG. 3 shows the position of the distributor 20 of ground bath at the base of the hopper 15.
  • the ground bath dispenser-dispenser 20 is also placed in a sealed sheath 21, and its dispenser 22 opens near the alumina dispenser 23, above an orifice 6.
  • the ground bath does not have the same qualities of fluidity as alumina.
  • this bath being recovered in the form of solid blocks, its grinding to a very fine particle size (less than a millimeter for example), would be an expensive operation, generating dust. It is therefore preferable to grind it to an average particle size (for example 0 to 6 mm or 0 to 10 mm) and to design the metering distributor so that it cannot remain blocked in an intermediate position, which would cause the total emptying of the crushed bath hopper, and a significant disturbance of the thermal equilibrium of the tank.
  • an average particle size for example 0 to 6 mm or 0 to 10 mm
  • the device illustrated in Figure 4 meets this requirement: it comprises a plate 24 fixed to the base of the hopper 15, for example by bolting. Under the plate is fixed the dosing cup 25 formed by a tubular body whose volume corresponds to a predetermined weight of ground bath which can be between 0.5 to 5 kg, for example 2 kg.
  • the lower end 26 is open and is extended by the adductor tube 22 which opens above the orifice 6.
  • the upper part 27 opens into the hopper.
  • An axial rod 28 is connected at its upper part to a jack 29 and carries, at its lower part, two lower and upper sealing means 30 and 31, spaced apart by a distance d1 less than the distance d2 between the upper openings and lower of the measuring cup 25.
  • the shutters 30 and 31 consist of flexible discs centered on the rod 28. It is advantageous to use metal brushes made of interlaced steel wires (rotary brushes), or even discs made of flexible material, such as felt, such as which or somewhat stiffened by a metallic canvas frame, for example, or else hard rubber or synthetic elastomers, possibly armed with steel wires, or equivalent alloys.
  • the rod 28 is guided at the base of the sheath 21, for example by a ring 32 with gentle friction which practically prevents any rise in the ground bath in the sheath 21.
  • the shutter 30 rests on the edges of the opening 26 or on the base of the cone forming the lower part of the cup 25. In this position, the cup 25 is filled with crushed bath. Returned to the high position under the action of the jack 29, the upper shutter 31 comes to bear on the edges of the opening 27, thus providing isolation of the hopper, while the contents of the bucket 25 pours into the orifice 6.
  • the flexibility and elasticity of the shutters 30 and 31 make it possible to seal even if a few crushed bath grains remain attached to the edges of the openings, thus avoiding any accidental emptying, partial or total, of the hopper 15 into the tank. .
  • the jack 29 is connected to the computer, as indicated above, so as to enter into action for any signal indicating that the bath level is lower than the set value.
  • Figure 5 shows the principle of measuring the metal level.
  • the height HM of the sheet of liquid aluminum is measured by reference to a fixed and known dimension point, with respect to the cathode substrate: rim of the box, vertical upright, horizontal beam.
  • the method will be described in the particular case where the reference point is located on the superstructure 11, but this does not imply any limitation of the invention.
  • DSC is known (distance between the superstructure 11 and the anode frame 33, movable in height to adjust the anode-cathode distance of the tank), thanks to a device such as the potentiometric displacement sensor 34.
  • DCPA is known, distance between the anode frame 33 and the anode plane 4A from the anode wear speed which is known fairly precisely, and remains constant in tanks in normal operation, for a given quality of anodes .
  • DAM anode-metal distance, which is considered constant for a given set value of the internal resistance of the tank, during periods of normal operation, without disturbances (such as anode effect, metal racking , change of anodes, lifting of the frame, etc ).
  • HM D1 - (DSC + DCPA + DAM)
  • HB (D1 - D2 - D3) - HM.
  • the height references DSC and DCPA must no longer be taken from the anode frame, but from one of the elements common to a group of anodes.
  • the HB setpoint remaining fixed at 20 cm, the fluctuations have been reduced to + -1 cm, and there has been no bath flow during the last six months .

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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)
EP88420122A 1987-04-21 1988-04-19 Procédé et dispositif de contrôle des additions d'électrolyte solide dans les cuves d'électrolyse pour la production d'aluminium Expired - Lifetime EP0288397B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8705874A FR2614320B1 (fr) 1987-04-21 1987-04-21 Procede et dispositif de controle des additions d'electrolyse solide dans les cuves d'electrolyse pour la production d'aluminium.
FR8705874 1987-04-21

Publications (2)

Publication Number Publication Date
EP0288397A1 EP0288397A1 (fr) 1988-10-26
EP0288397B1 true EP0288397B1 (fr) 1991-07-24

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EP88420122A Expired - Lifetime EP0288397B1 (fr) 1987-04-21 1988-04-19 Procédé et dispositif de contrôle des additions d'électrolyte solide dans les cuves d'électrolyse pour la production d'aluminium

Country Status (19)

Country Link
US (1) US4857157A (forum.php)
EP (1) EP0288397B1 (forum.php)
CN (1) CN1019514B (forum.php)
AU (1) AU603204B2 (forum.php)
BR (1) BR8801909A (forum.php)
CA (1) CA1335436C (forum.php)
DE (1) DE3863827D1 (forum.php)
ES (1) ES2024042B3 (forum.php)
FR (1) FR2614320B1 (forum.php)
GR (1) GR3002356T3 (forum.php)
HU (1) HU207540B (forum.php)
IN (1) IN169735B (forum.php)
IS (1) IS1432B6 (forum.php)
MY (1) MY103264A (forum.php)
NO (1) NO171419C (forum.php)
NZ (1) NZ224238A (forum.php)
OA (1) OA08833A (forum.php)
SA (1) SA90100107B1 (forum.php)
SU (1) SU1597109A3 (forum.php)

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AU645567B2 (en) * 1990-10-05 1994-01-20 Portland Smelter Services Pty. Ltd. Apparatus for controlled supply of alumina
EP0604664A4 (en) * 1992-06-30 1995-01-25 Tovarischestvo S Ogranichennoi METHOD FOR PRODUCING ALUMINUM AND OTHER METALS.
RU2032773C1 (ru) * 1992-06-30 1995-04-10 Товарищество с ограниченной ответственностью "Межотраслевой центр проблем экологии и эффективности производства алюминия" Способ получения алюминия
FR2727985B1 (fr) * 1994-12-09 1997-01-24 Pechiney Aluminium Procede et dispositif de mesure de la temperature et du niveau du bain d'electrolyse fondu dans les cuves de production d'aluminium
US7122252B2 (en) * 2002-05-16 2006-10-17 Cardinal Cg Company High shading performance coatings
RU2245399C1 (ru) * 2003-08-21 2005-01-27 Общество с ограниченной ответственностью "Инженерно-технологический центр" Способ определения формы рабочего пространства алюминиевого электролизера с верхним токоподводом
CN101052749B (zh) * 2004-09-08 2012-12-12 E.C.L.公司 包括阳极位置调整在内的电解铝池阳极更换方法以及实施该方法的装置
FR2884524B1 (fr) * 2005-04-19 2007-06-15 Aluminium Pechiney Soc Par Act Dispositif de controle de la course d'une pointerolle d'un systeme d'alimentation d'une cellule d'electrolyse de production d'aluminium
RU2307880C1 (ru) * 2005-12-22 2007-10-10 Общество с ограниченной ответственностью "Русская инжиниринговая компания" Способ определения высоты слоя расплавленного алюминия на подине электролизера
US20100294671A1 (en) * 2006-06-22 2010-11-25 Nguyen Thinh T Aluminium collection in electrowinning cells
DE102007059962B3 (de) * 2007-12-11 2008-12-11 Robert Bosch Gmbh Vorrichtung zum Messen des Metallniveaus in einem Reduktionsbecken
US20100155259A1 (en) * 2008-12-19 2010-06-24 Ramaswamy J Process for online power cut out of an aluminum reduction cell
RU2398054C1 (ru) * 2009-03-10 2010-08-27 Юрий Анатольевич Щербаков Устройство для определения уровней металла и электролита в электролизере для получения алюминия
US8409409B2 (en) * 2009-03-26 2013-04-02 Alcoa Inc. System, method and apparatus for measuring electrolysis cell operating conditions and communicating the same
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
RU2425180C2 (ru) * 2009-05-21 2011-07-27 Общество с ограниченной ответственностью "Объединенная Компания РУСАЛ Инженерно-технологический центр" Способ управления алюминиевым электролизером
RU2425178C2 (ru) * 2009-07-02 2011-07-27 Семен Игоревич Ножко Способ измерения уровней расплавов металла и электролита на электролизере для производства алюминия
CN102691076B (zh) * 2012-06-27 2014-11-26 云南铝业股份有限公司 一种断续灌注电解质的电解槽启动方法
SG11201506454TA (en) * 2013-02-21 2015-09-29 Gtc Technology Us Llc Separation processes using divided columns
CN105297076A (zh) * 2014-06-06 2016-02-03 新疆农六师煤电有限公司 一种铝电解槽电解质高度、铝液高度自动测量装置
CN104480496B (zh) * 2015-01-09 2017-03-29 中南大学 一种测量铝电解槽熔体高度和炉底压降的装置和方法
EP3266904B1 (de) 2016-07-05 2021-03-24 TRIMET Aluminium SE Schmelzflusselektrolyseanlage und regelungsverfahren zu deren betrieb
FR3065014B1 (fr) * 2017-04-10 2019-06-28 Fives Ecl Procede de mise en place d'une couverture d'anode dans une cellule d'electrolyse, machine de service apte a mettre en oeuvre un tel procede et produit programme d'ordinateur pour la mise en oeuvre d'un tel procede
CN107497793B (zh) * 2017-09-30 2024-03-12 中冶赛迪技术研究中心有限公司 一种铝槽打壳锤头超声振动清洗装置及方法
CN108330509B (zh) * 2018-03-16 2020-04-24 杨钧福 铝电解槽全智能打壳系统
CN116397272A (zh) * 2023-04-11 2023-07-07 云南国钛金属股份有限公司 一种多极性镁电解槽液位标定的方法

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SU387028A1 (ru) * 1972-02-14 1973-06-21 УСТРОЙСТВО дл ОПРЕДЕЛЕНИЯ ВЕСА АЛЮМИНИЯ, '^ ЭЛЕКТРОЛИЗЕРА В ВАКУУМНЫЙ КОВШ
CH587357A5 (forum.php) * 1973-08-09 1977-04-29 Alusuisse
CH592749A5 (forum.php) * 1974-01-30 1977-11-15 Alusuisse
US4045308A (en) * 1976-11-04 1977-08-30 Aluminum Company Of America Bath level set point control in an electrolytic cell and method of operating same
DE3565864D1 (en) * 1985-03-18 1988-12-01 Alcan Int Ltd Controlling aluminium reduction cell operation

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Publication number Publication date
NZ224238A (en) 1990-02-26
IS3333A7 (is) 1988-10-22
NO881705D0 (no) 1988-04-20
CN88102179A (zh) 1988-11-23
GR3002356T3 (en) 1992-12-30
OA08833A (fr) 1989-03-31
CA1335436C (fr) 1995-05-02
AU1478488A (en) 1988-10-27
IN169735B (forum.php) 1991-12-14
AU603204B2 (en) 1990-11-08
HU207540B (en) 1993-04-28
HUT49656A (en) 1989-10-30
FR2614320B1 (fr) 1989-06-30
FR2614320A1 (fr) 1988-10-28
DE3863827D1 (de) 1991-08-29
MY103264A (en) 1993-05-29
US4857157A (en) 1989-08-15
SA90100107B1 (ar) 2000-10-14
NO171419B (no) 1992-11-30
IS1432B6 (is) 1990-07-16
NO171419C (no) 1993-03-10
EP0288397A1 (fr) 1988-10-26
BR8801909A (pt) 1988-11-22
NO881705L (no) 1988-10-24
CN1019514B (zh) 1992-12-16
ES2024042B3 (es) 1992-02-16
SU1597109A3 (ru) 1990-09-30

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