US3509030A - Casing liner - Google Patents

Casing liner Download PDF

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Publication number
US3509030A
US3509030A US690882A US3509030DA US3509030A US 3509030 A US3509030 A US 3509030A US 690882 A US690882 A US 690882A US 3509030D A US3509030D A US 3509030DA US 3509030 A US3509030 A US 3509030A
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Prior art keywords
anode
casing
liner
aluminum
paste
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Expired - Lifetime
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US690882A
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English (en)
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Matthew Ernest Gooding
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Alcan Research and Development Ltd
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Alcan Research and Development Ltd
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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
    • C25C3/12—Anodes
    • C25C3/125—Anodes based on carbon

Definitions

  • the liner is in contact with and substantially conforms to the shape or configuration or dimensions of the interior of the lower portion of the anode casing but is spaced from the interior of the upper portion of the anode casing to provide space between the upper portion of the anode casing and the liner for the introduction of suitable insulating material therebetween.
  • the metal liner particularly an aluminum metal liner, provides a surface to which the baked anode is less adherent, thereby permitting easier downward movement of the anode within the casing for maintaining contact with the electrolyte and reducing the likelihood of anode paste leaks into the electrolyte.
  • This invention relates to an anode casing structure useful in the electrolytic process for the manufacture of aluminum.
  • electric current is passed through a carbonaceous anode, a molten alumina-containing electrolyte and a cathode with the resulting formation of molten elemental aluminum at the cathode; for more details of the electrolytic process for the manufacture of aluminum see US. Patents 3,024,178 and 3,251,763, the disclosures of which are herein incorporated and made a part of this disclosure.
  • the anode is oxidized and gradually consumed and must be replaced.
  • V.S. vertical stud
  • anode material or paste is added to the top of an open-end steel casing, generally rectangular in cross section, which contains the anode and within which the anode moves downwardly into contact with the alumina-containing electrolyte and is gradually consumed.
  • Vertical studs or conductors are implanted into the anode to support it and supply it with electrical energy. They move downward with the anode, and as they approach the molten elec- 3,509,030 Patented Apr.
  • anode paste is added to the anode within the casing to replace that portion of the anode consumed in the aluminum production process.
  • the amount of anode paste added to the anode is substantially at the rate at which the anode is consumed during the aluminum production process.
  • the anode material or paste added to the anode casing is a mixture of a binder, such as pitch or tar in an amount usually in the range 20-40% by weight of the paste, and a solid carbonaceous material, such as petroleum coke or anthracite and mixtures thereof.
  • a binder such as pitch or tar in an amount usually in the range 20-40% by weight of the paste
  • a solid carbonaceous material such as petroleum coke or anthracite and mixtures thereof.
  • the anode paste thus supplied to the anode is usually substantially solid in appearance, particularly at room temperature, since the melting point of the binder material is about C. more or less. More fluid or paste-like anode material may be employed by employing a lower melting point pitch or tar as the binder.
  • the anode paste within the anode casing is gradually heated. Although at first the anode paste appears solid, upon heating it becomes more fluid and tends to flow and uniformly fill the anode casing. As the, now more fluid, anode paste moves downwardly within the anode casing, it is subjected to still higher temperatures and at a temperature of about 300- 400 C. the anode paste tends to lose some of the more volatile constituents and becomes baked to a hard, somewhat porous, electrically conductive, carbonaceous mass.
  • This hard, baked carbonaceous mass then moves downwardly within the anode casing for eventual contact with the alumina-containing electrolyte where it is con sumed.
  • a vertical stud anode in the electrolytic process for the manufacture of aluminum difficulty frequently arises due to the movement of the anode within the anode casing or the failure of the anode to move within the anode casing.
  • a steel casing is regularly employed as the casing for a vertical stud anode.
  • the baked anode material due to localized overheating tends to form hard carbonaceous masses or corns which adhere very tenaciously to the steel casing and prevent or make very difiicult the downward movement of the anode.
  • Another object of this invention is to provide an improved anode casing structure which tends to reduce or eliminate corns" and anode paste leaks.
  • Still another object of this invention is to provide an anode casing structure for a vertical stud anode which makes possible better and more uniform temperature control of the anode paste and the anode material within the anode casing.
  • Yet another object of this invention is to provide an anode casing structure which presents a surface to the anode material within the casing which permits an easier movement of the anode within the anode casing.
  • FIG. 1 is a broken plan view of a vertical stud anode casing structure showing the liner, the anode material and the vertical studs;
  • FIG. 2 is a transverse cross sectional view of a vertical stud anode as employed in an electrolytic cell for the manufacture of aluminum;
  • FIG. 3 is a perspective view of a liner suitable for use as the liner of a vertical stud anode casing, the casing portion with respect to the liner being outlined by dashed lines;
  • FIG. 4 is a fragmentary cross sectional view taken along lines 44 of FIG. 3, illustrating a liner made up of a material of uniform thickness;
  • FIG. 5 is a cross sectional view similar to FIG. 4 illustrating an embodiment in accordance with the practice of this invention wherein the lower portions or sections of the liner structure have a greater thickness than the upper portions or sections;
  • FIG. 6 is a cross sectional view taken along lines 66 of FIG. 5; and wherein FIG. 7 is a cross sectional view similar to that of FIG. 6 wherein the lower portions of the end sections of the casing liner have a greater thickness than the other portions or sections of the liner.
  • Aluminum is particularly useful as the material making up the anode casing liner since the anode material, i.e. the Soderberg or anode paste, liquid or baked, does not readily bond or adhere to aluminum, particularly as compared to steel. Additionally, aluminum has a much higher thermal conductivity than steel and therefore improves the temperature distribution of the anode material within the anode casing structure to the most desirable condition for efiicient operation.
  • the anode material i.e. the Soderberg or anode paste, liquid or baked
  • a liner made up of a metal having a higher thermal conductivity than the casing or the outer shell of the anode structure heat is readily conducted away from the lower, relatively hot portions of the anode, particularly those portions of the anode closest to and/or in direct contact with the hot gases covering the molten alumina-containing electrolyte and in contact with the electrolyte itself which is usually maintained at a temperature in the range 930-1000 C. during the aluminum production operation.
  • the use of a high heat conductivity metal liner within the anode casing, such as an aluminum liner, which presents a surface which does not readily bond or adhere to the anode material within the casing permits a more easy downward movement of the anode within the casing structure.
  • the liner also provides for the conduction of heat from the lower,
  • the liner also greatly reduces or eliminates the likelihood of formation of corns adhering to the inside of the anode casing structure which sometimes cause paste leaks with resultant reduction in cell efficiency and increased cost.
  • Soderberg or anode paste upon baking, does not stick to an aluminum metal surface as easily or as readily as to a steel surface. Also, if the baking anode paste does adhere to the alumi num metal surface the bond between the anode material and the aluminum surface can readily be broken, leaving a clean aluminum surface. In contrast, baking anode paste material tends to strongly adhere to a steel surface and the bond between the steel surface and the anode material tends to be stronger than the baked anode material itself.
  • a metal liner made up of a metal having a higher heat conductivity than the material, usually steel, making up the anode casing or outer shell of the anode casing structure and by spacing the liner from the interior of the upper portion of the anode casing and introducing insulation material, such as plywood, asbestos, rock wool, fiberglass and the like, into the annular space between the liner and the casing in the upper portion of the anode structure, a very improved and more uniform temperature distribution within the anode material is obtained.
  • insulation material such as plywood, asbestos, rock wool, fiberglass and the like
  • the aluminum liner more readily removes heat from those areas of the anode exposed to high temperatures, such as that portion of the anode material eloser to the hot, molten electrolyte, and conducts and distributes this heat to those portions of the anode material requiring more heat and an increased temperature for a more efficient operation.
  • An anode casing structure in accordance with this invention tends to eliminate or reduce overheating of the anode material and excessive baking of the anode material with the resulting formation of carbon corns which tend to firmly attach themselves to the interior of the anode casing structure and cause anode paste leaks and other related troubles.
  • An anode casing structure in accordance with this invention also serves to keep the Soderberg or anode paste within the upper portion of the anode casing more 'fiuid and relatively uniform in surface temperature and also in good consistency for the planting and reimplanting of the vertical studs used to supply the electrical energy to the anode.
  • An anode casing structure in accordance with this invention tends to eliminate rims of frozen paste which usually adhere to the casing during wintertime operations, thereby permitting a reduction in the proportion of anode paste binder used in the preparation of the anode paste and removing non-conformities from the sliding zone of the anode.
  • An anode casing structure in accordance with this invention assures the supply of enough heat, and a sufliciently high temperature, to the bottom corners or ends of a relatively low current density, wide vertical stud anode casing so as to bake the Soderberg or anode paste adequately before it emerges from the anode casing structure for eventual contact with the hot molten electrolyte.
  • the desired heat conservation and temperature control with respect to the anode material within the anode casing is effected. This permits attainment of more uniformity with respect to temperature at various levels within the anode..
  • the material or metal making up the casing liner has a higher heat conductivity than the material or metal making up the anode casing or outer shell of the anode casing structure.
  • steel is the preferred material for the fabrication of the anode casing or outer shell of the anode casing structure.
  • steel is the preferred material for the fabrication of the anode casing or outer shell of the anode casing structure.
  • aluminum metal and its alloys are preferred.
  • Other metals which would appear to be useful for the fabrication of the anode casing liner, particularly in combination with a steel casing include titanium, copper, magnesium and their alloys.
  • FIGS. 1 and 2 there is illustrated a vertical stud anode assembly or arrangement used in the electrolytic process for the manufacture of aluminum.
  • Anode is contained within an anode casing assembly or structure generally indicated by reference numeral 11.
  • the anode casing structure is made up of a casing liner 12 supported on and fixed to casing 14.
  • Vertical stud conductors 15 are schematically illustrated in FIG. 1.
  • the vertical stud conductors, illustrated in greater detail in FIG. 2 are made up of electrical conductors 16 fixed to studs 18 by suitable fasteners 19.
  • anode 10 which, from a temperature and physical point of view, may be considered to be comprised of three zones or sections, the upper zone or section 10a of the anode being made up of substantially fluid paste at the lowest temperature, with the intermediate zone 10b beneath consisting of semi-baked and baking paste, at a higher temperature and substantially solid in appearance, although containing a high proportion of unbaked hydrocarbons.
  • anode section 10c is made up of baked anode paste and is relatively hard, solid, self-supporting, electrically conductive material and is at a substantially higher temperature than the remaining portions 10a and 10b of the anode material.
  • the lowermost portion of anode 10, section 100 is shown in contact with a bath of alumina-containing electrolyte 20.
  • annular space 28 may be unoccupied or filled with suitable heat insulating material, such as plywood, asbestos or rock or glass wool, or any other suitable material, having the desired heat insulating properties and the ability to resist the conditions in this area.
  • suitable heat insulating material such as plywood, asbestos or rock or glass wool, or any other suitable material, having the desired heat insulating properties and the ability to resist the conditions in this area.
  • the purpose of providing annular space 28 between the upper portions of casing liner 12 and casing 14 is for heat conservation so as to better conserve and utilize heat Withdrawn from the hotter portions of anode 10, Le. portions 10c and 10b, and from the hot gases covering electrolyte 20 to the uppermost zone 10a of the anode.
  • This arrangement in accordance with this invention has been found to provide a more uniform heat and temperature distribution within anode 10, particularly in the upper zones 10a and 10b.
  • annular space 28 between casing liner 12 and casing 14 may include only the upper /3 or upper A of the height of casing 14.
  • annular space 28 may include as much as or /3 or of the upper portion of casing 14, but must terminate above the baked zone 10c and preferably above the semi-baked zone 10b.
  • the height of annular space 28 depends upon the size of casing 14, the operating conditions of the cell for the manufacture of aluminum, the composition of the anode paste, the size of casing 14 and easing liner 12 both with respect to length and the thickness making up the casing and liner and the temperature conditions desired within anode 10 and the levels and extent of the various zones 10a, 10b and 10c making up anode 10.
  • the thickness of the material or metal making up casing liner 12 may be in the range /s to about 1" more or less and the width of annular space 28 separating casing liner 12 from casing 14 may be in the range /s" to about 1 /2", such as /2, A or 1".
  • the upper end of easing liner 12 is provided with a flange portion 12a which is fixed to and/or supported on flange portion 14a of casing 14.
  • a sealing strip 29 of suitable material such as heat insulating material.
  • the lower end of casing 14 is provided with a bottom flange 14b which supports gas collecting shroud or skirt 25.
  • the lower casing flange 14b may be suitably provided with fins 14 for temperature control, fins 14c serving to radiate or dissipate excess heat from casing 14 of the anode structure or assembly.
  • FIGS. 3 and 4 show casing liner 12 in accordance with one embodiment of this invention wherein the material, such as aluminum, making up casing liner 12 is of uniform thickness, such as a thickness of 0.25".
  • end portions 12 are joined to side portions 120 by means of straps 13 of about the same thickness as end and side portions 12b and 12c and which are attached or otherwise fixed to ends 12b and or the sides 12c.
  • the gap covered by straps 13 separating ends 121) and sides 120 may be any suitable dimension to suit differential thermal expansion of aluminum and steel or other metals, such as 0.51.5", e.g. 1".
  • the outline of casing 14 and its relationship to liner 12 is indicated by dashed lines.
  • straps 13 fastening portions 12b and 120 these portions can be overlapped and then fastened together with bolts with enlarged holes to allow for expansion.
  • FIGS. 5 and 6 illustrate another embodiment of a casing liner in accordance with this invention wherein liner sides 12c and the bottom sections of liner ends 12b are of the same, uniform thickness but wherein the upper portions of the liner ends 1212b have a smaller thickness than the lower poLtions.
  • .1 2b. Straps 13 joining liner sides 12c and liner ends 12b and 12bb may have any suitable thickness, such as the thickness of liner sides 120 or the thickness of the material making up liner end portions 12b or 1211b.
  • FIG. 7 illustrates yet another embodiment of a casing liner in accordance with this invention wherein liner ends 1211 are made up of a material of uniform thickness but a thickness greater than the material making up liner sides 12c and wherein ends 12b and sides 12c overlap and are joined as described before.
  • a structure useful for supporting and containing the anode material of a vertical stud anode employed in the electrolytic process for the manufacture of aluminum comprising an open-end casing, said casing being substantially rectangular in cross section, and a metal liner fixed to and provided within said casing, said liner being in contact with and substantially conforming to the inner surface of said casing within the lower portion or end thereof and said liner being spaced from the inner surface of said casing within the upper portion or end to provide space between said liner and said casing, said metal liner being made up of a metal having a greater heat conductivity than the material making up said casing.
  • said casing is a steel casing and wherein said liner is a metal liner selected from the group consisting of magnesium, aluminum, titanium and alloys thereof.
  • said casing is a steel casing and'wherein said metal liner is made up of aluminum, the aluminum making up said liner being uniform in thickness.
  • said casing is a steel casing and wherein said metal liner is made up of aluminum, the thickness of the aluminum making up said liner within the lower portion or end of said casing being greater than the thickness of the aluminum making up said liner within the upper portion or end of said casing.
  • said casing is a steel casing and wherein the metal liner is made up of aluminum, the thickness of the aluminum in contact with the ends of the lower portion of said casing being greater than the thickness of the aluminum making up the other sections or sides of said liner.
  • a process in accordance with claim 10 wherein the material making up said casing is steel of substantially uniform thickness and wherein the metal making up said liner is aluminum.
  • a process in accordance with claim 10 wherein the material making up said casing is steel of substantially uniform thickness and wherein the metal making up said liner is aluminum and wherein the thickness of said aluminum liner is greater than the thickness of the steel making up said casing.
  • a method in accordance. with claim 10 wherein the metal making up said liner is a magnesium alloy.
  • a method in accordance with claim 10 wherein the metal making up said liner is an aluminum alloy.
  • a method in accordance with claim 10 wherein the metal making up said liner is a titanium alloy.
  • a method in accordance with claim 10 wherein the metal making up said liner is aluminum, the lower portion of the aluminum metal making up said liner having a thickness greater than the aluminum metal making up the upper portion of said liner.
  • a method of improving the operation of a vertical stud anode in the electrolytic process for the manufacture of aluminum wherein the anode prepared from anode paste is contained and supported within an openend substantially rectangular casing which comprises providing said casing with a metal liner substantially conforming to and in contact with the interior of the lower portion of said casing, the metal making up said liner having a higher heat conductivity than the material making up said casing, maintaining said casing in direct contact with said liner around the interior of the lower portion of said casing and insulating the interior of the upper portion of said casing from said liner by providing a space intermediate said liner and the upper portion of said casing, the combination of said metal liner in contact with the lower portion of said casing and the conservation of heat in said anode by providing insulating space intermediate said liner and the upper portion of said casing serving to provide a more uniform heating of said anode and temperature distribution within the anode within said casing.

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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)
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US690882A 1967-12-15 1967-12-15 Casing liner Expired - Lifetime US3509030A (en)

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ES (1) ES361397A1 (enrdf_load_html_response)
FR (1) FR1596031A (enrdf_load_html_response)
GB (1) GB1235907A (enrdf_load_html_response)
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3855086A (en) * 1973-06-28 1974-12-17 Aluminum Co Of America Carbon anode protection in aluminum smelting cells
US3945906A (en) * 1974-06-06 1976-03-23 Reynolds Metals Company Anode lining system
US3960696A (en) * 1974-06-18 1976-06-01 Gebr. Giulini Gmbh Aluminum electrolysis furnace
CN106471160A (zh) * 2014-07-04 2017-03-01 力拓艾尔坎国际有限公司 阳极组件

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1691505A (en) * 1925-05-15 1928-11-13 Norske Elektrokemisk Ind As Electrode
US2193434A (en) * 1937-04-08 1940-03-12 Norske Elektrokemisk Ind As Electrode with slide contacts
US2339230A (en) * 1943-04-17 1944-01-11 Norske Elektrokemisk Ind As Suspension of self-baking electrodes
US2769113A (en) * 1951-09-18 1956-10-30 Kaiser Aluminium Chem Corp Self-baking electrode

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1691505A (en) * 1925-05-15 1928-11-13 Norske Elektrokemisk Ind As Electrode
US2193434A (en) * 1937-04-08 1940-03-12 Norske Elektrokemisk Ind As Electrode with slide contacts
US2339230A (en) * 1943-04-17 1944-01-11 Norske Elektrokemisk Ind As Suspension of self-baking electrodes
US2769113A (en) * 1951-09-18 1956-10-30 Kaiser Aluminium Chem Corp Self-baking electrode

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3855086A (en) * 1973-06-28 1974-12-17 Aluminum Co Of America Carbon anode protection in aluminum smelting cells
US3945906A (en) * 1974-06-06 1976-03-23 Reynolds Metals Company Anode lining system
US3960696A (en) * 1974-06-18 1976-06-01 Gebr. Giulini Gmbh Aluminum electrolysis furnace
CN106471160A (zh) * 2014-07-04 2017-03-01 力拓艾尔坎国际有限公司 阳极组件
CN106471160B (zh) * 2014-07-04 2018-10-16 力拓艾尔坎国际有限公司 阳极组件

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OA02955A (fr) 1970-12-15
ES361397A1 (es) 1970-11-01
GB1235907A (en) 1971-06-16
NO123106B (enrdf_load_html_response) 1971-09-27
SE348003B (enrdf_load_html_response) 1972-08-21
FR1596031A (enrdf_load_html_response) 1970-06-15

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