US3514520A - Linings of electrolysis,remelting,and similar furnaces,containing molten metals,alone or together with molten salts - Google Patents

Linings of electrolysis,remelting,and similar furnaces,containing molten metals,alone or together with molten salts Download PDF

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Publication number
US3514520A
US3514520A US701485A US3514520DA US3514520A US 3514520 A US3514520 A US 3514520A US 701485 A US701485 A US 701485A US 3514520D A US3514520D A US 3514520DA US 3514520 A US3514520 A US 3514520A
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furnaces
silicon carbide
electrolysis
molten
layers
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US701485A
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English (en)
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Roberto Bacchiega
Giorgio Olah De Garab
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Montedison SpA
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Montedison SpA
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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
    • C25C3/085—Cell construction, e.g. bottoms, walls, cathodes characterised by its non electrically conducting heat insulating parts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • Our invention relates to the linings of furnaces for containing molten metals, molten metals and salts, such as electrolysis furnaces, remelting furnaces and the like.
  • our invention relates to furnaces for fused bath electrolysis of aluminum oxide in cryolite, for aluminum production.
  • our invention faces and solves one of the most important problems met in the construction of such furnaces, that is, the problem of the so-called seal of the furnaces. That is the problem of avoiding the seepage of the molten metal through the material constituting the side walls and the bottom of the furnace vats.
  • the problem is particularly serious in the building of the vat of electrolysis furnaces, e.g. the furnaces for the production of aluminum and magnesium.
  • the inner surface of the vat that holds the molten metal and the bath, is generally lined by one or more layers of special refractory bricks, prebaked carbon blocks or carbonaceous materials in general. These layers are in direct contact with the fused bath and/or the molten metal.
  • blocks or carbonaceous material are placed refractory bricks and thermoinsulating bricks.
  • the discontinuities and cracks that may form in the vat are points of easy leakage for the liquid within the vat itself, primarily for the molten metal.
  • the molten metal has a solidification temperature much lower than that of the fused bath in which it is produced.
  • the multicell electrolysis furnaces with suspended bipolar electrodes for aluminum production in contact with the fused cryolite bath is an inner layer of special refractory material, for instance silicon nitridebonded silicon carbide, often followed by a layer of carbonaceous material. These layers are outwardly followed by one or more layers of thermally insulating material, and encompassed by an iron shell.
  • the electrolysis furnaces of the conventional type used in the fused bath electrolysis having a similar vat, but these vats are usually lacking an inner lining of refractory material.
  • the carbon either in blocks or as a ramming, which replaces the cathode in them, is in direct contact with the bath, and/or metal.
  • silicon carbide in an incoherent state that is, in the form of powder or granules, without a binder, even in a very thin layer and in commercial grain size, constitutes a barrier practically unsurmountable for molten metal, particularly for molten aluminum even when mixed with an electrolytic bath, for instance with molten cryolite salts. It therefore suifices to interpose layers of this material between layers constituting the vats of the furnaces in question and/or by stuffiing the silicon carbide into the interstices between bricks and/or between the'carbon blocks, in order to eliminate the leaking through of the aluminum and the ensuing damage.
  • the build up of these layers is carried out by spreading the incoherent silicon carbide between layers on the bottom of the furnace vats and by pouring it into interstices purposely left in the side walls of the vats.
  • Layers of 1 cm. or more are definitly efficient, very thin layers e.g. of 1 mm. and more, exert the same surprising effect.
  • the powdery or granulated silicon carbide layer is preferably interposed between the layer of said refractory bricks forming the internal lining and the layer of carbonaceous material adjacent to it.
  • the layer of powdery or granulated silicon carbide is arranged all around and beneath the layer of carbon blocks or rammed carbon, being careful, however, not to insulate electrically the cathodic iron bars. It is quite feasible to so place the silicon carbide since experience shows that the zones most exposed to leakages of the aluminum, and thus most needful of protection inside the furnaces, are those zones located at the ledge of the vat bottom, that is, the zones joining the bottom to the side walls.
  • the protective layer of silicon carbide powder or granules is placed against, i.e. on the outside of, the first refractory brick layer, which is in direct contact with the molten metal.
  • FIG. 1 shows a longitudinal cross section along the longitudinal axis of the vat in a conventional aluminum electrolysis furnace operating on monopolar electrodes (anodes) and with a cathodic bottom;
  • FIG. 2 shows in detail, on a larger scale, a transverse cross section of the cathodic vat of FIG. 1;
  • FIG. 3 shows a longitudinal cross section along the longitudinal axis of the vat of a multicell furnace
  • FIG. 4 shows a transverse cross section of the vat of FIG. 3.
  • the outer iron shell is 1 while 2 is the prebaked anthracitous carbon blocks.
  • the side walls of the vat, also of prebaked anthracitous are 3.
  • An anthracitous ramming baked in situ is shown at 4.
  • Number 5 marks the iron cathode bars.
  • the interposed silicon carbide powder or granules 6 are not drawn to scale, that is, they show an apparently greater thickness than necessary.
  • the silicon carbide powder or granules 10 is between the internal lining 11 of special refractory and the carbon layer 12 (ramming or blocks), which constitues the vat proper. This in turn is within external insulating layer 13 (refractory and/or thermal insulant), which is within the iron shell 14.
  • EXAMPLE A multicell furnace for the electrolytic production of aluminum, fitted with a protective layer according to the invention and with vats built according to FIGS. 3 and 4, was kept in operation for several months. After this period, a cracking of the bottom was noticed. Upon dismantling of the furnace itself, a certain leakage of electrolytic bath was ascertained. This, however, had solidified between the carbon and the external insulation, while the molten aluminum, quite surprisingly, had not passed through the granulated silicon carbide layer.
  • Blank tests were carried out contemporaneously to the tests using siilcon carbide layers according to this invention.
  • blank tests were mean trials under equal condiitions, but omitting the silicon carbide layer.
  • These blank tests had severe metal leakages, clearly showing the protective effect against such leakages was a result of the silicon carbide.
  • vats are lined with layers of carbonaceous material in direct contact with the molten mass within said vat.
  • vat comprises layers of carbonaceous material and layers of special refractory material, interposed between the layers of carbonaceous material and the molten mass within the furnace -vat.
  • furnaces are electrolysis furnaces.
  • furnaces of claim 10 wherein the furnaces are fused bath electrolysis.
  • furnaces of claim 10 wherein the furnaces are for the electrolytic production of metals.
  • furnaces of claim 12 wherein the furnaces are for the production of aluminum.
  • furnaces of claim 10 wherein the furnaces have monopolar electrodes and a cathodic bottom.
  • furnaces of claim 10 wherein the furnaces are multicell furnaces with bipolar electrodes.
  • furnaces of claim 1 wherein the furnaces are melting furnaces.
  • furnaces of claim 1 wherein the furnaces are remelting furnaces.

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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)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Laminated Bodies (AREA)
US701485A 1967-02-01 1968-01-29 Linings of electrolysis,remelting,and similar furnaces,containing molten metals,alone or together with molten salts Expired - Lifetime US3514520A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT1215767 1967-02-01

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US3514520A true US3514520A (en) 1970-05-26

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US (1) US3514520A (da)
AT (1) AT290153B (da)
BE (1) BE710194A (da)
CH (1) CH496932A (da)
DE (1) DE1608030A1 (da)
ES (1) ES350013A1 (da)
FR (1) FR1553345A (da)
NO (1) NO121622B (da)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3661736A (en) * 1969-05-07 1972-05-09 Olin Mathieson Refractory hard metal composite cathode aluminum reduction cell
US3666654A (en) * 1968-09-24 1972-05-30 Giorgio Olah De Garab Furnaces with bipolar electrodes for the production of metals, particularly aluminum, through electrolysis of molten salts, equipped with auxiliary heating facilities
US3766025A (en) * 1972-06-30 1973-10-16 Aluminum Co Of America Repairing electrolytic cells
US3767375A (en) * 1968-10-30 1973-10-23 Glaverbel Refractory furnace tank walls
US3777043A (en) * 1973-01-17 1973-12-04 Neill Corp O Apparatus and method for cooling a refractory lining
US3787311A (en) * 1970-12-12 1974-01-22 Giulini Gmbh Geb Cathode for the winning of aluminum
US3856650A (en) * 1972-03-21 1974-12-24 Alusuisse Cathode for an aluminium fusion electrolysis cell and method of making the same
US4052288A (en) * 1976-01-13 1977-10-04 Aluminium Pechiney Process for brasquing fused electrolysis cells
US4537671A (en) * 1982-07-12 1985-08-27 Swiss Aluminium Ltd. Cathode pot of an aluminum reduction cell
US4561958A (en) * 1984-11-30 1985-12-31 Reynolds Metals Company Alumina reduction cell
US5876584A (en) * 1995-05-26 1999-03-02 Saint-Gobain Industrial Ceramics, Inc. Method of producing aluminum

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4175022A (en) * 1977-04-25 1979-11-20 Union Carbide Corporation Electrolytic cell bottom barrier formed from expanded graphite
EP0193491A1 (de) * 1985-02-15 1986-09-03 Schweizerische Aluminium Ag Elektrolysewanne
EP0197003A1 (de) * 1985-03-22 1986-10-08 Schweizerische Aluminium Ag Elektrolysewanne für die Herstellung von Aluminium

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3256173A (en) * 1960-10-28 1966-06-14 Alusuisse Electrolytic furnace with lined cathode pots for the production of aluminum
US3321392A (en) * 1962-09-07 1967-05-23 Reynolds Metals Co Alumina reduction cell and method for making refractory lining therefor
US3412195A (en) * 1965-08-05 1968-11-19 Haveg Industries Inc Intermediate furnace barrier

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3256173A (en) * 1960-10-28 1966-06-14 Alusuisse Electrolytic furnace with lined cathode pots for the production of aluminum
US3321392A (en) * 1962-09-07 1967-05-23 Reynolds Metals Co Alumina reduction cell and method for making refractory lining therefor
US3412195A (en) * 1965-08-05 1968-11-19 Haveg Industries Inc Intermediate furnace barrier

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3666654A (en) * 1968-09-24 1972-05-30 Giorgio Olah De Garab Furnaces with bipolar electrodes for the production of metals, particularly aluminum, through electrolysis of molten salts, equipped with auxiliary heating facilities
US3767375A (en) * 1968-10-30 1973-10-23 Glaverbel Refractory furnace tank walls
US3661736A (en) * 1969-05-07 1972-05-09 Olin Mathieson Refractory hard metal composite cathode aluminum reduction cell
US3787311A (en) * 1970-12-12 1974-01-22 Giulini Gmbh Geb Cathode for the winning of aluminum
US3856650A (en) * 1972-03-21 1974-12-24 Alusuisse Cathode for an aluminium fusion electrolysis cell and method of making the same
US3766025A (en) * 1972-06-30 1973-10-16 Aluminum Co Of America Repairing electrolytic cells
US3777043A (en) * 1973-01-17 1973-12-04 Neill Corp O Apparatus and method for cooling a refractory lining
US4052288A (en) * 1976-01-13 1977-10-04 Aluminium Pechiney Process for brasquing fused electrolysis cells
US4537671A (en) * 1982-07-12 1985-08-27 Swiss Aluminium Ltd. Cathode pot of an aluminum reduction cell
US4561958A (en) * 1984-11-30 1985-12-31 Reynolds Metals Company Alumina reduction cell
US5876584A (en) * 1995-05-26 1999-03-02 Saint-Gobain Industrial Ceramics, Inc. Method of producing aluminum

Also Published As

Publication number Publication date
BE710194A (da) 1968-07-31
FR1553345A (da) 1969-01-10
NO121622B (da) 1971-03-22
DE1608030A1 (de) 1970-10-29
ES350013A1 (es) 1969-04-16
AT290153B (de) 1971-05-25
CH496932A (de) 1970-09-30

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