WO2003006717A1 - Cellule electrolytique dote d'un dispositif d'alimentation en poudre ameliore - Google Patents

Cellule electrolytique dote d'un dispositif d'alimentation en poudre ameliore Download PDF

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Publication number
WO2003006717A1
WO2003006717A1 PCT/IB2002/002689 IB0202689W WO03006717A1 WO 2003006717 A1 WO2003006717 A1 WO 2003006717A1 IB 0202689 W IB0202689 W IB 0202689W WO 03006717 A1 WO03006717 A1 WO 03006717A1
Authority
WO
WIPO (PCT)
Prior art keywords
powder material
batches
feed pipes
metal
molten electrolyte
Prior art date
Application number
PCT/IB2002/002689
Other languages
English (en)
Other versions
WO2003006717A8 (fr
Inventor
Georges Berclaz
Jean-Jacques Duruz
Original Assignee
Moltech Invent S.A.
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 Moltech Invent S.A. filed Critical Moltech Invent S.A.
Priority to CA002450097A priority Critical patent/CA2450097A1/fr
Priority to AU2002321682A priority patent/AU2002321682A1/en
Priority to EP02755395A priority patent/EP1404898A1/fr
Publication of WO2003006717A1 publication Critical patent/WO2003006717A1/fr
Priority to NO20040088A priority patent/NO20040088L/no
Publication of WO2003006717A8 publication Critical patent/WO2003006717A8/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F11/00—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it
    • G01F11/28—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with stationary measuring chambers having constant volume during measurement
    • G01F11/30—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with stationary measuring chambers having constant volume during measurement with supply and discharge valves of the lift or plug-lift type
    • G01F11/34—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with stationary measuring chambers having constant volume during measurement with supply and discharge valves of the lift or plug-lift type for fluent solid material
    • 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
    • C25C3/14—Devices for feeding or crust breaking

Definitions

  • the present invention relates to a device for feeding powder material to different areas of a molten electrolyte of a metal electrowinning cell.
  • the powder material may be a compound of the metal to be electrowon or one or more constituents of the electrolyte.
  • the technology for the production of aluminium by the electrolysis of alumina, dissolved in molten cryolite containing salts, at temperatures around 950°C is more than one hundred years old and still uses carbon anodes and cathodes .
  • alumina is fed to the molten electrolyte for its subsequent dissolution and electrolysis.
  • Conventional cells are operated with a crust of frozen electrolyte above the molten electrolyte which crust needs to be periodically broken to form an opening for feeding alumina into the molten electrolyte situated underneath.
  • Improper alumina feeding to the electrolyte can lead on the one hand to local oversaturation of alumina and precipitation of undissolved alumina onto the cell bottom with decline in efficiency, and on the other hand to depletion ' of dissolved alumina which leads to anode effects when the anodes are made of carbon or to electrolytic dissolution of the anodes when they are made of a metal- based material .
  • alumina point feeders for aluminium production cells for instance as disclosed in US Patent 3,901,787 (Niizeki/Watanabe/Yamamoto/Takeuchi/Kubota) , feed alumina to different areas of a molten electrolyte of an aluminium production cell using several feed pipes connected to the same alumina reservoir. Each feed pipe has an alumina metering device or an alumina gate for feeding batches of alumina to each area of the molten electrolyte.
  • WO00/63464 discloses another alumina feeder of an aluminium production cell in which batches of alumina supplied from a reservoir through several feed pipes are sprayed over the molten electrolyte.
  • US Patent 3,681,229 discloses an alumina feeder with an alumina metering device for supplying a metered amount of alumina to a horizontal conveyor duct which extends along an aluminium production cell and along which the powder alumina is fluidised and carried by pressurised air.
  • the conveyor duct is provided with apertures leading into corresponding feed pipes for feeding alumina to a plurality of different feed locations of the cell. The size of these apertures determines approximately the amount of alumina supplied from the conveyor duct to the feed pipes.
  • the invention relates to a device for intermittently supplying powder material to a plurality of feed pipes, i.e. at least 2 and usually 3 to 8 or more feed pipes, for feeding batches of the powder material to different areas of a molten electrolyte in a metal electrowinning cell.
  • the device of the invention may be used in a cell for the electrolytic production of aluminium or of another metal, for feeding to the electrolyte of the cell a compound of the metal to be produced or one or more constituents of the electrolyte, for example Al 2 0 3 , A1F 3 , NaF, CaF 2 , MgF 2 or LiF can be fed to a cryolite-based aluminium production electrolyte.
  • a compound of the metal to be produced or one or more constituents of the electrolyte for example Al 2 0 3 , A1F 3 , NaF, CaF 2 , MgF 2 or LiF can be fed to a cryolite-based aluminium production electrolyte.
  • Suitable aluminium production cells in which such a feed device can be used are for example disclosed in US patent 6,258,246 (Duruz/de Nora), WO00/63463 (de Nora), WO01/31086 (de Nora/Duruz) , WO01/31088, PCT/IB02/00668, PCT/IB02/0670 , PCT/IB01/00953 and PCT/IB01/00956 (all de Nora) .
  • the device comprises means for metering quantities of powder material and for intermittently dropping the metered quantities over at least one inclined and/or upright dividing surface where each metered quantity of the powder material is divided as it drops over the dividing surface (s) into a plurality of batches which correspond to the plurality of feed pipes and which are directed to the corresponding feed pipes .
  • the dividing surface (s) can be inclined and preferably upwardly converging.
  • the dividing surface (s) is/are of generally conical or pyramidal shape.
  • the device comprises a plurality of upright dividing surfaces .
  • the upright dividing surfaces are surfaces of concurrent upright plates radially arranged and defining between them a plurality of compartments into which each metered quantity of powder material is divided after having been dropped over the upright plates .
  • the dividing surface (s) is/are in a housing having a plurality of openings in correspondence with the plurality feed pipes.
  • the metering means comprises a metering chamber having a volume corresponding to the amount of powder material of each metered quantity, the metering chamber having an inlet for incoming powder material from a feedstock, usually stored in a reservoir, and an outlet for outgoing metered quantities of powder material to the dividing surface (s) .
  • the metering means may comprise a movable closure member for closing the inlet of the metering chamber coupled with a movable closure member for closing the outlet of the metering chamber such that when the inlet is closed the outlet is open and vice-versa.
  • the invention also relates to a device for intermittently feeding batches of powder material to different areas of a molten electrolyte in a metal electrowinning cell.
  • the feed device comprises a reservoir for storing the powder material and a plurality of feed pipes for feeding the batches of the powder material to the different areas of the molten electrolyte.
  • the reservoir and the feed pipes are connected through a device as described above which is arranged to divide metered quantities of the powder material into the batches of the powder material and direct the batches to the feed pipes .
  • compressed air may be supplied into the feed pipes to fluidise the powder material therein and facilitate the transport of the powder material in the feed pipes towards the molten electrolyte.
  • gravity may be sufficient to displace the powder material in the feed pipes to the molten electrolyte.
  • a further aspect of the invention relates to a cell for the electrowinning of a metal from ions of the metal in a molten electrolyte, in particular a cell for the production of aluminium, comprising a feed device for feeding batches of a powder material to different areas of the molten electrolyte as described above.
  • the device may contain and supply to the molten electrolyte a compound of the metal to be electrowon, in particular alumina for the electrowinning of aluminium.
  • a cell for the electrowinning of a metal from ions of the metal in a molten electrolyte comprising a device as described above for intermittently supplying powder material to a plurality of feed pipes for feeding batches of the powder material to different areas of the molten electrolyte.
  • Yet another aspect of the invention relates to a method of producing a metal, in particular aluminium by the electrolysis of an aluminium compound dissolved in a molten electrolyte.
  • the method comprises passing an electrolysis current in a molten electrolyte containing a dissolved compound of the metal between an anode and a cathode to produce the metal at the cathode and intermittently dropping metered quantities of powder material, in particular selected from at least one of the metal compound and constituents of the molten electrolyte, over at least one inclined and/or upright dividing surface where each metered quantity of powder material is divided as it drops over the dividing surface (s) into a plurality of batches which correspond to said plurality of feed pipes and which are directed to said corresponding feed pipes that feed the batches of powder material to different areas of the molten electrolyte.
  • the appended drawing schematically and by way of example shows an aluminium electrowinning cell using an alumina feed device according to the invention.
  • the aluminium production cell shown in the appended drawing comprises a plurality of oxygen evolving anodes 10 dipping in a molten electrolyte 5 over a cell bottom.
  • the cell bottom comprises a series of pairs of spaced apart carbon cathode blocks 25 placed across the cell and having an aluminium-wettable upper layer 22.
  • the aluminium-wettable layer 22 is covered with aluminium-wettable openly porous plates 21 which are filled with molten aluminium to form an aluminium-wetted drained active cathode surface 20 above the upper surfaces 22 of the carbon cathode blocks 25.
  • the cathode blocks 25 are made of graphite and have a reduced height, e.g. 30 cm, and are coated with the aluminium-wettable layer 22 to protect the graphite from erosion and wear.
  • Suitable aluminium-wettable layers are disclosed in WO01/42168 (de Nora/Duruz), WO01/42531 (Nguyen/Duruz/de Nora) and PCT/IB01/00949 (Nguyen/de Nora) .
  • the cell bottom further comprises a centrally- located recess 35 at a level below the upper surfaces 22 of the carbon cathode blocks 25 and which during use collects molten aluminium 60 drained from the aluminium-wettable drained active cathode surface 20.
  • the aluminium collection recess 35 is formed in a reservoir body 30 which is placed between the blocks 25 of each pair of cathode blocks and spaces them apart across the cell. As shown, the recess 35 formed in the reservoir body 30 is generally U-shaped with rounded lower corners and an outwardly curved upper part .
  • the reservoir body 30 is made of two generally L-shaped sections 31 assembled across the cell. The reservoir sections 31 are made of anthracite-based material.
  • the aluminium-wettable layer 22 also covers the surface of recess 35 to protect the reservoir body 30 during use against wear and sodium intercalation.
  • the reservoir body 30 extends below the cathode blocks 25 into the refractory insulating material 26 of the cell bottom permitting a maximisation of the capacity of the aluminium collection recess 35.
  • the reservoir body 30 has a solid base 32 which extends from above to below the bottom face of the cathode blocks 25 and provides sufficient mechanical resistance to keep the blocks 25 properly spaced apart across the cell when subjected to thermal expansion during start-up of the cell and normal operation.
  • Longitudinally spaced apart spacer bars (not shown) placed across an upper part of the recess 35 may provide additional mechanical strength to the reservoir body 30.
  • Such spacer bars can be made of carbon material coated with an aluminium-wettable protective layer.
  • the openly porous plates 21 placed on the upper surfaces 22 of the carbon cathode blocks 25 and located in the central region of the cell bottom extend over part of the aluminium collection recess 35 so that during use the protruding part of the aluminium-wetted drained active cathode surface 20 is located over the recess 35.
  • the openly porous plates 21 are spaced apart over the aluminium collection recess 35 to leave an access for the tapping of molten aluminium through a conventional tapping tube.
  • the spacing between the openly porous plates 21 over the aluminium collection recess can be much smaller along the remaining parts of the recess 35, thereby maximising the surface area of the active cathode surface 20.
  • the illustrated cell comprises a series of corner pieces 41 which are made of the same openly porous material as plates 21 filled with aluminium and which are placed at the periphery of the cell bottom against sidewalls 40.
  • the sidewalls 40 and the surface of the electrolyte 5 are covered with a ledge and a small crust of frozen electrolyte 6.
  • the cell is fitted with an insulating cover 45 above the electrolyte crust 6 to reduce thermal losses. Further details of suitable covers are disclosed in WOOl/31086 (de Nora/Duruz) and PCT/IB02/00669 (de Nora/Berclaz) .
  • the cell is also provided with an exhaust pipe 46 that extends through the cover 45 for the removal of gases produced during electrolysis, in particular anodically evolved oxygen.
  • the cell comprises a device 50 for intermittently feeding batches of powder material 65, for example alumina, to different areas of the molten electrolyte 5.
  • the device 50 has a reservoir 54 for storing the alumina 65 and a plurality of feed pipes 52, for instance four feed pipes 52 only two of which are shown, for feeding batches of alumina 65 to the different areas of the molten electrolyte 5 adjacent anodes 10.
  • the feed pipes 52 extend through the insulating cover 45 between anodes 10. It is usually sufficient to have one feed pipe for supplying alumina to a group of two or four anodes 10, the total number of feed pipes depending on the size of the cell. Each feed pipe 52 is associated with a crust breaker (not shown) for breaking the crust 6 and forming an opening 7 underlying the feed pipe 52 prior to feeding.
  • the feed device 50 has a dividing arrangement with a housing 53 having at its bottom a plurality of openings leading into the feed pipes 52 and a generally conical dividing surface 51 which is located between these openings and- which divides metered quantities of powder alumina 65 dropped thereover into the batches and which directs these batches to the corresponding feed pipes 52.
  • the shape of the dividing surface 51 can be adapted to divide the metered quantities of powder alumina 65 into unequal portions, for instance when the different feed pipes 52 feed alumina to different groups of anodes having an unequal number of anodes .
  • the feed device 50 also comprises an alumina metering device which comprises a volumetric metering chamber 55 having a volume corresponding to the amount of powder material of each metered quantity.
  • the metering chamber 55 has an inlet with an upper movable closure member 56a for controlling incoming powder alumina 65 from reservoir 54 and an outlet with a lower movable closure member 56b for controlling outgoing metered quantities of powder alumina 65 to the dividing arrangement 51,53.
  • the upper and lower movable closure members 56a, 56b are mechanically coupled on a shaft 57 which can be vertically reciprocated by a motor 58 simultaneously to close the inlet and open the outlet, and vice-versa.
  • alumina dissolved in the electrolyte 5 is electrolysed to produce oxygen on the anodes 10 and aluminium 60 on the drained cathode surfaces 20.
  • the product aluminium 60 drains from the cathode surfaces 20 into the reservoir 30 from where it can be tapped.
  • Alumina 65 is intermittently fed from reservoir 54 to the molten electrolyte 5 through feed pipes 52 by raising shaft 52 to let alumina powder 65 fill the metering chamber 55, then lowering shaft 52 to deliver a metered quantity of alumina powder 65 over the conical dividing surface 51 where it is divided into substantially equal batches which are directed into the corresponding feed pipes 52.
  • the batches are then fed through pipes 52 to different areas of electrolyte 5 between different groups of anodes 10 at different locations 7 that, if necessary, are maintained crust-free by a reciprocating crust breakers (not shown) that penetrate the crust below the lower end of the feed pipes 52.
  • the insulating material of the sidewalls 40 and cover 45 may be sufficient to prevent formation of any ledge and crust of frozen electrolyte.
  • the sidewalls 40 are preferably completely shielded from the molten electrolyte 5 by a lining of the aforesaid openly porous material filled with aluminium.
  • the anodes 10 are preferably made of electrolyte resistant inert metal-based material.
  • Suitable metal-based anode materials include iron alloys comprising nickel and/or cobalt which may be heat-treated in an oxidising atmosphere as disclosed in WO00/06802, WO00/06803 (both Duruz/de Nora/ Crottaz), WO00/06804 (Crottaz/Duruz) , WO01/42535 (Duruz/de Nora), WO01/42534 (de Nora/Duruz) and WO01/42536 (Duruz/ Nguyen/de Nora) .
  • the cell may be operated with an electrolyte 5 at reduced temperature, typically from about 850° to 940°C, preferably from 880° to 930°C.
  • Suitable electrolyte compositions are disclosed in PCT/IB01/00954 (Nguyen/de Nora) .
  • Operating with an electrolyte at reduced temperature reduces the solubility of oxides, in particular of alumina. For this reason, it is advantageous to enhance alumina dissolution in the electrolyte 5 by feeding it to different areas of the electrolyte 5 as provided by the present invention.
  • the cell may comprise means (not shown) to promote circulation of the electrolyte 5 from and to the anode-cathode gap to enhance alumina dissolution in the electrolyte 5 and to maintain in permanence a high concentration of dissolved alumina close to the active surfaces of anodes 10, for example as disclosed in WO00/40781 (de Nora) or WO01/31088 (de Nora) .

Abstract

L'invention concerne un dispositif conçu pour fournir, par intermittence, un matériau en poudre (65) à une multitude de tuyaux d'alimentation (52) afin de fournir des charges de matériau en poudre (65) à différentes zones d'un électrolyte fondu (5) dans une cellule d'extraction électrolytique de métal. Le dispositif décrit dans cette invention comprend un dispositif (54, 55, 56a, 57, 58) permettant de mesurer des quantités de matériau en poudre et de déverser, par intermittence, les quantités mesurées sur au moins une surface de séparation (51) inclinée et/ou verticale présentant une forme conique ou pyramidale. Chaque quantité de matériau en poudre (65) mesurée est séparée en une multitude de charges au fur et à mesure que ledit matériau en poudre se déverse sur la ou les surfaces de séparation (51); ces charges correspondent aux multiples tuyaux d'alimentation (52) et sont acheminées vers eux.
PCT/IB2002/002689 2001-07-11 2002-07-09 Cellule electrolytique dote d'un dispositif d'alimentation en poudre ameliore WO2003006717A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002450097A CA2450097A1 (fr) 2001-07-11 2002-07-09 Cellule electrolytique dote d'un dispositif d'alimentation en poudre ameliore
AU2002321682A AU2002321682A1 (en) 2001-07-11 2002-07-09 Electrolytic cell with improved powder feed device
EP02755395A EP1404898A1 (fr) 2001-07-11 2002-07-09 Cellule electrolytique dote d'un dispositif d'alimentation en poudre ameliore
NO20040088A NO20040088L (no) 2001-07-11 2004-01-09 Elektrolysecelle med forbedret pulverpåmatningsinnretning

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IB0101249 2001-07-11
IBPCT/IB01/01249 2001-07-11

Publications (2)

Publication Number Publication Date
WO2003006717A1 true WO2003006717A1 (fr) 2003-01-23
WO2003006717A8 WO2003006717A8 (fr) 2005-03-24

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PCT/IB2002/002689 WO2003006717A1 (fr) 2001-07-11 2002-07-09 Cellule electrolytique dote d'un dispositif d'alimentation en poudre ameliore

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EP (1) EP1404898A1 (fr)
AU (1) AU2002321682A1 (fr)
CA (1) CA2450097A1 (fr)
NO (1) NO20040088L (fr)
WO (1) WO2003006717A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005017234A1 (fr) 2003-08-14 2005-02-24 Moltech Invent S.A. Cellule d'extraction electrolytique d'un metal comprenant un purificateur electrolytique
WO2010126354A1 (fr) * 2009-04-28 2010-11-04 N.V. Nutricia Emballage de poudre
CN103132105A (zh) * 2011-11-24 2013-06-05 贵阳铝镁设计研究院有限公司 电解质粉配料及贮存输送系统装置
CN113564641A (zh) * 2021-07-28 2021-10-29 贵阳铝镁设计研究院有限公司 一种新型氧化铝与电解质自动配比覆盖料储运系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110042430B (zh) * 2019-05-10 2020-07-31 中南大学 氧化铝下料系统及其下料方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH650591A5 (en) * 1980-12-24 1985-07-31 Alusuisse Device for the proportioned supply of fine-grained pourable bulk material
US5324408A (en) * 1990-10-05 1994-06-28 Portland Smelter Services Pty. Ltd. Apparatus for controlled supply of alumina
RU2114217C1 (ru) * 1996-06-06 1998-06-27 Акционерное общество открытого типа "Братский алюминиевый завод" Устройство для автоматической подачи глинозема в алюминиевый электролизер

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH650591A5 (en) * 1980-12-24 1985-07-31 Alusuisse Device for the proportioned supply of fine-grained pourable bulk material
US5324408A (en) * 1990-10-05 1994-06-28 Portland Smelter Services Pty. Ltd. Apparatus for controlled supply of alumina
RU2114217C1 (ru) * 1996-06-06 1998-06-27 Акционерное общество открытого типа "Братский алюминиевый завод" Устройство для автоматической подачи глинозема в алюминиевый электролизер

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005017234A1 (fr) 2003-08-14 2005-02-24 Moltech Invent S.A. Cellule d'extraction electrolytique d'un metal comprenant un purificateur electrolytique
WO2010126354A1 (fr) * 2009-04-28 2010-11-04 N.V. Nutricia Emballage de poudre
US8245736B2 (en) 2009-04-28 2012-08-21 N.V. Nutricia Powder packaging
CN103132105A (zh) * 2011-11-24 2013-06-05 贵阳铝镁设计研究院有限公司 电解质粉配料及贮存输送系统装置
CN103132105B (zh) * 2011-11-24 2016-05-11 贵阳铝镁设计研究院有限公司 电解质粉配料及贮存输送系统装置
CN113564641A (zh) * 2021-07-28 2021-10-29 贵阳铝镁设计研究院有限公司 一种新型氧化铝与电解质自动配比覆盖料储运系统

Also Published As

Publication number Publication date
NO20040088L (no) 2004-01-09
AU2002321682A1 (en) 2003-01-29
EP1404898A1 (fr) 2004-04-07
WO2003006717A8 (fr) 2005-03-24
CA2450097A1 (fr) 2003-01-23

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