US3579432A - Electrolytic reduction cell - Google Patents

Electrolytic reduction cell Download PDF

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Publication number
US3579432A
US3579432A US761421A US3579432DA US3579432A US 3579432 A US3579432 A US 3579432A US 761421 A US761421 A US 761421A US 3579432D A US3579432D A US 3579432DA US 3579432 A US3579432 A US 3579432A
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United States
Prior art keywords
plate
aluminum
rod
ferrous metal
ferrous
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Expired - Lifetime
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US761421A
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English (en)
Inventor
Walter D Finnegan
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Kaiser Aluminum and Chemical Corp
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Kaiser Aluminum and Chemical Corp
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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
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
    • 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
    • C25C3/16—Electric current supply devices, e.g. bus bars

Definitions

  • This invention relates to electrical conductors useful in electrolytc cells employing electrodes supported by individual bars or rods of conductor material It is particularly applicable to electrolytc cells for the reduction of aluminum containing compounds, e.g. alumina, for the production of aluminum.
  • aluminum containing compounds e.g. alumina
  • the metal aluminum is extracted from aluminum-bearing compounds such as alumina (A1203) by electrolysis from a molten salt bath or electrolyte.
  • the electrolytc cell comprises in general a steel shell having disposed therein a carbon lining.
  • the bottom of the carbon lining together with a layer of electrolytically produced molten aluminum which collects thereon during operation serves as the cathode.
  • One or more consumable carbon electrodes is disposed from the top of the cell and is immersed at its lower extremity into a layer of molten electrolyte which is disposed in the cell.
  • the electrolyte or bath which is a mixture of alumina and cryolite, is charged to the cell and an electric current is passed through the cell from the anode to the cathode via the layer of molten electrolyte.
  • the alumina is dissociated by the current so that aluminum is deposited on the liquid aluminum cathode and oxygen is liberated at the carbon anode, forming carbon monoxide and carbon dioxide gas.
  • a crust of solidified electrolyte and alumina forms on the surface of the bath, and this is usually covered over with additional alumina.
  • the reduction process involves precisely the same chemical reactions.
  • the principal difference is one of structure.
  • the carbon anodes are prebaked before being installed in the cell while in the Soderberg, or self-baking anode cell, the anode is baked in situ, that is, it is baked during operation of the electrolytc cell, thereby utilizing part of the heat generated by the reduction process.
  • the instant invention is applicable to either cell.
  • a carbon anode is used in aluminum reduction cells.
  • the electrical current required to eifect reduction is conveyed from a bus bar through an anode rod assembly to the stub of ferrous metal embedded in and supporting the anode.
  • the anode rod consists of a rectangular copper bar or rod that is joined to the ferrous stub.
  • the copper rod or bar is joined to a ferrous metal hanger to which ferrous metal stubs are attached. In either case, a connnection is required between the anode rod and a fer- 3,579,432 Patented May 18, 1971 rous metal member.
  • the ferrous metal assembly shall be referred to in all cases as a stub whether the connection be directly to the stub or via a hanger which is subsequently connected to the stub.
  • Service requirements dictate that the union 'be strong, have low electrical resistance and be unaffected by the heat that it is necessarily exposed to during use.
  • a similar arrangement is used in the cathode.
  • One or more ferrous metal rods or collector bars are embedded in the carbonaceous portion of the cathode.
  • the ferrous metal rod or collector bar is connected to a flexible connector which in turn is connected to the negative or cathode bus bar of the cell.
  • Copper is particularly suited to use as the anode rod or bar.
  • copper is becoming in increasingly short supply and the price of the available material has risen sharply, Accordingly, a substitute material must be found.
  • Aluminum metal or aluminum alloys such as that known as electrical conductor grade (EC) aluminum are good electrical conductors and would seem suited for this purpose.
  • the oxide film normally present on aluminum effects current conductivity from the aluminum to the ferrous metal.
  • EC electrical conductor grade
  • a bolted connection is not satisfactory for aluminum because joint resistance becomes excessive as relaxation occurs through creeps of the aluminum member. Solders are melted due to the heat of the cell. Fusion welding and brazing are ruled out because a brittle intermetallic layer is formed between the aluminum ller metals and the ferrous metal member of the assembly.
  • the instant invention was developed against this background in the art.
  • an electrolytc reduction cell which comprises a lining which denes a cavity adapted to contain an electrolyte, and an anode disposed within the cavity.
  • a flexible bus conductor is connected to an anode bus bar above the cavity in combination with an electrical connection plate attached to the flexible bus conductor and positioned above the cavity.
  • a ferrous metal stub is embedded in and supports the anode.
  • a ferrous metal plate having a soft aluminous plate roll bonded along one face thereto is affixed to the end of the stub not embedded in the anode.
  • An aluminum conductor rod is welded to the aluminous plate roll bonded to the steel plate. Means are provided for holding the conductor rod and electrical connection plate in current transmitting contact.
  • At least the bottom section of the cell lining is part of the cathode.
  • a ferrous metal rod or collector bar is embedded in this part of the lining.
  • a ferrous metal plate may be affixed to the end of the rod not embedded in the electrode. If the instant invention is applied to this assembly, a soft aluminous plate is roll bonded along one face to the ferrous plate aixed to the rod.
  • An aluminum conductor rod (or flexible connector) is Welded to the aluminous plate roll bonded to the ferrous plate and is adapted to be connected to the cathode bust bar.
  • the ferrous metal plate is welded to the ferrous metal stub.
  • the ferrous metal plate is bolted to the stub, the head of the bolt may be recessed in a hole provided in the aluminous plate of the assembly.
  • Another variation of the bolted joint involves roll bonding a second ferrous metal plate to the opposite side of the aluminous plate from the rst ferrous plate. In this way when the aluminous plate is welded to the aluminum conductor rod the ferrous plates are adapted to extend along opposite sides of the stub and the bolt can pass through both of them.
  • FIG. 1 is a front elevational view partly in section of a reduction cell embodying the principles of the instant invention.
  • FIG. 2 is a front elevational view partly in section of an electrolytic cell embodying the principles of the instant invention.
  • FIG. 3 is a partial view of a connection between the rod and stub in accordance with the principles of the instant invention.
  • FIG. 4 is a partial view showing another form of the connection between the rod and stub in accordance with the instant invention.
  • FIG. 5 is a View of another connection between the rod and stub in accordance with the principles of the instant invention.
  • FIG. 6 is a View of another connection between the rod and stub in accordance with the principles of the instant invention.
  • an aluminum reduction cell 10 having a carbon lining 12 which defines a cavity indicated generally at 14 adapted to contain a molten aluminum pad 16 and an electrolyte or bath 18 consisting essentially of alumina dissolved in cryolite.
  • Carbon lining 12 is supported by a shell 20 of suitable material such as steel, a layer of insulation 22 being provided between lining 12 and shell 20.
  • a layer of insulation 22 being provided between lining 12 and shell 20.
  • Anodes 24 may be of the prebaked type as shown in FIG. 1 or the continuous or self-baking or Soderberg type as shown in FIG. 2.
  • a ferrous metal stub 26 is embedded in and supports the anode. As shown in FIG. 1, stub 26 may in reality consist of two pieces, a bracket plate 26a and a stub 26 proper. An anode bus bar 28 is positioned above cavity 14.
  • a ferrous metal plate 30 is affixed in an appropriate manner to the end of stub 26 not embedded in the anode. If desired, additional material such as a furane binder or cast iron may be used to insure that the stub 26 is properly embedded in and supports the anode 24. As has been discussed hereinabove and as shall be discussed more fully hereinafter, the ferrous metal plate may be affixed in diverse -ways to the end of stub 26. In the embodiments shown in FIGS. 1 and 2, ferrous metal plate 30 is fusion welded to stub 26. A soft aluminous plate 32 is roll bonded along one face to plate 30. Commercially pure aluminum, i.e. that known as 1100 grade aluminum is acceptable for this purpose or electrical conductor grade (EC) aluminum is also acceptable for this purpose. In any event, the aluminum or aluminum base alloy should be readily plastically deformable at the bonding temperature.
  • An aluminum anode or conductor rod 34 is welded to the aluminous plate 32 roll bonded to plate 30.
  • Appropriate means such as clamp 36 are provided for holding the conductor rod 34 and anode bus bar 28 in current transmitting contact.
  • a ferrous metal cathode rod or collector bar 38 is connected to a cathode bus bar 40 in an appropriate manner as by exible connector 42.
  • the cathode rod 38 shown here embedded in carbon lining 12, is in any event positioned in the cell 10 so that when an electrical power source, not shown, is connected across the anode bus bar 28 and the cathode bus bar 40, electrical current will flow between the anode 24 and the cathode system, comprising the collector bar 38, lining 12 and molten aluminum pad 16 via the electrolyte or bath 18 contained in cavity 14.
  • connection between cathode rods 38 and flexible connectors 42 can be made in a manner similar to the connection between the anode rod 34 and stub 26. That is, a transition insert of the same type can be used with the ferrous metal plate 30 of the insert affixed to the end of the collector bar or cathode rod 38.
  • the soft aluminous plate 32 is roll bonded along one face to the ferrous plate 30 affixed to the stub or collector or cathode rod 38.
  • the exible connector, or aluminum conductor rod is welded to the aluminous plate 32 roll bonded to the ferrous metal plate 30. It is then connected in an appropriate manner to cathode bus bar 40 which in turn is connected to a source of electric current as has been explained previously.
  • FIG. 3 The embodiment shown in FIG. 3 is similar to that of FIG. 1 with the exception that only a single rather than a double stub 26 is connected by means of the transition insert.
  • the anode rod 34 is welded -to the aluminous plate 32 and the ferrous metal stub 2'6 is welded to the ferrous metal layer or plate 30.
  • FIGS. 4 and 5 show a slightly different assembly.
  • the transition insert contains a layer of ferrous metal 30 and a layer of aluminous material 32 or, in the case of FIG. 5, a central ferrous metal layer 30 to which layers of aluminous material 32 have been roll bonded on both sides.
  • the construction shown in FIGS. 4 and 5 permit the use of a bolted union because the bolting is effected between the plate 30 of the insert and the ferrous metal stub 26 of the assembly, a union that is serviceable in reduction cells.
  • the aluminous layers or plates 32 of the insert can be trimmed back to leave a projecting length of ferrous metal plate 30. 11n such case, the projecting length of ferrous metal must be of sufficient cross sectional area .to carry the electrical current.
  • a hole large enough to accommodate the head of the attaching bolt can be cut in the aluminous plate 32 and a smaller one in the ferrous metal plate 30 to accommodate the shaft of the bolt.
  • the aluminous plate 32 would carry current to the portions of the ferrous plate 30 that are held in contact with the stub 26 by bolting pressure. In such case, the current carrying capacity of the ferrous plate 30 depends on the cross sectional area. of bolting contact and a relatively thin layer of ferrous metal would suflice.
  • au assembly composed of an insert containing a central aluminous plate 32 to which ferrous metal plates 30 have been roll bonded on both sides. This construction also enables bolting to be used to connect the anode assembly to a stub 26 or similar member.
  • plates of 3A thick electrical conductor grade aluminum were degreased and abrasively cleaned using a grit belt sander.
  • Electrical conductor grade aluminum is 99.45% pure aluminum. This is essentially a slightly higher purity than commercially pure or 1100 grade aluminum which is 99% pure aluminum. Plates of 1A" to 1/2" thick type 304 stainless steel Were also degreased and belt sanded using a 150 grit abrasive belt.
  • the composition of 304 stainless steel may be expressed as 0.06% carbon, 1.84% manganese, 0.02% phosphorous, 0.01% sulfur, 0.54% silicon, 9% nickel, 18% chromium, 0.25% molybdenum, 0.21% copper, and 0.10% cobalt with the remainder essentially iron.
  • the composition limits of type 6 304 stainless steel are lil-20% chromium, 8-1l% nickel, Metallographic examination of the samples of 1100 0.08% maximum carbon, manganese 2.0% maximum, 1008 explosion bounded and the 1100/ 1020 after an the balance essentially iron.
  • the Cleaned plates were laid exposure of one month at 800 F. revealed an appreciable together so the sanded faces were in Contact With each intermetallic layer in the explosion bounded and no other.
  • the laid up pack was heated to 550 F. and reduced intermetallic formation in the roll bonded material.
  • 1008 carbon steel has 1.
  • the nominal composition of 1008 carbon steel is comprises:
  • s 3003 0.6 Si; 0.7 Fe; 0.20 Cu; 1.0-1.5 Mn; 0.10 Zn; others 0.05 ea., 0.15 total, balance aluminum.
  • the composite electrical conductor of claim 1 the material temperature 930 800 660 540 ferrous metal rod of which is embedded in an electrode formed of carbonaceous material lmonth "d0"" OK""' 0K” References Cited EC Bfda t i1 0K 60 U @es e@ Broi'roiifffii UNITED STATES PATENTS oK OK do 2,880,157 3/1959 'Wleugel 204-286X imonth 1o OK OK---- 65 3,424,668 1/1969 Fischer 204286X 1100/100s 2 hr Broke.-.

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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)
  • Respiratory Apparatuses And Protective Means (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)
  • Arc Welding In General (AREA)
US761421A 1968-09-23 1968-09-23 Electrolytic reduction cell Expired - Lifetime US3579432A (en)

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US76142168A 1968-09-23 1968-09-23

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US (1) US3579432A (enrdf_load_stackoverflow)
JP (1) JPS502845B1 (enrdf_load_stackoverflow)
DE (1) DE1947957B2 (enrdf_load_stackoverflow)
FR (1) FR2022186A1 (enrdf_load_stackoverflow)
GB (1) GB1264669A (enrdf_load_stackoverflow)
NO (1) NO125146B (enrdf_load_stackoverflow)
SE (1) SE346123B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170151622A1 (en) * 2015-11-30 2017-06-01 Illinois Tool Works Inc. Welding process wire feeder adapter insulator
WO2018018158A1 (en) * 2016-07-29 2018-02-01 Hatch Ltd. Flexible electrical connectors for electrolytic cells

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2147628C1 (ru) * 1998-12-15 2000-04-20 Акционерное общество открытого типа "Всероссийский алюминиево-магниевый институт" Зажим алюминиевого электролизера с обожженными анодами
DE102010041082A1 (de) * 2010-09-20 2012-03-22 Sgl Carbon Se Kathode für Eletrolysezellen
CN110831865B (zh) 2017-07-04 2022-04-01 株式会社柏原制袋 片材制继流阀及带有继流阀的袋

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170151622A1 (en) * 2015-11-30 2017-06-01 Illinois Tool Works Inc. Welding process wire feeder adapter insulator
US12076825B2 (en) * 2015-11-30 2024-09-03 Illinois Tool Works Inc. Welding process wire feeder adapter insulator
WO2018018158A1 (en) * 2016-07-29 2018-02-01 Hatch Ltd. Flexible electrical connectors for electrolytic cells
CN109845039A (zh) * 2016-07-29 2019-06-04 哈奇有限公司 用于电解池的柔性电气连接器
US10855040B2 (en) 2016-07-29 2020-12-01 Hatch Ltd. Flexible electrical connectors for electrolytic cells
CN109845039B (zh) * 2016-07-29 2021-05-25 哈奇有限公司 用于电解池的柔性电气连接器

Also Published As

Publication number Publication date
GB1264669A (enrdf_load_stackoverflow) 1972-02-23
DE1947957B2 (de) 1979-12-13
FR2022186A1 (enrdf_load_stackoverflow) 1970-07-31
DE1947957A1 (de) 1970-04-02
NO125146B (enrdf_load_stackoverflow) 1972-07-24
JPS502845B1 (enrdf_load_stackoverflow) 1975-01-29
SE346123B (enrdf_load_stackoverflow) 1972-06-26

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