Classifications

• • 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
  • C25C3/08—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

Definitions

• the present invention relates to a cathode structure for an aluminium electrolysis cell.
• Electrolysis cells for aluminium production based upon the Hall-Heroult principle commonly have prebaked anodes in its upper part and a cathode structure in its lower part.
• the cathode structure comprises mainly an outer steel shell provided with vertical stiffeners and horizontal beams at its outside which are made out of steel too, the cathode structure further being provided with layers of protective and insulating material at its inside.
• In the mainly horizontal bottom part of the cathode structure there is commonly arranged electronic conducting carbon blocks.
• the cathode structure when in operation, contains a molten aluminium metal pad and above that molten bath material having temperatures that can be approximately 970° or even higher.
• the main feature of the outer steel shell including its stiffeners and beams is to maintain the geometric and dimensional configuration of the cathode structure during its lifetime of operation. Due to continuous chemical swelling of the cathode and lining as well the high temperatures involved and the effect this has on the properties of lining and steel components involved, several attempts have been carried out to make the steel shell structure and the configuration of stiffeners able to withstand this influence in a long lasting manner.
• appropriate cooling may relieve some of the harmful effects of the temperature in the steel shell to prevent aging of the steel and collapsing of mechanical properties like strength, elasticity, etc.
• stiffening structure in a manner that allows surrounding air to pass close to the shell structure.
• US 4087345 disclose a cathode structure designed to be cooled by natural cooling and where there are arranged ducts or passages between vertical stiffeners outside the cathode shell for allowing an upward draught of air.
• Horizontal beams arranged as a part of the stiffening structure are arranged onto the outside of the vertical stiffeners.
• US 4,322,282 disclose a tank for an electrolytic cell provided with horizontal movable hollow sections secured to the sidewalls of the metal tank. The sections bend inwards as a result of the temperature gradient across them such that they counter a pressure on the sidewalls due to the dilation of the cell contents, thus acting as a thermo-spring. There is provided holes in opposing horizontal walls of the hollow section so as to reduce thermal conduction within the sections and thereby maintain the temperature gradient therein. The circulation of air which results, helps further to achieve and maintain the temperature difference.
• At least one horizontal web is arranged in contact with the steel shell without intermediate vertical members that may, as a result of thermal loads, alter their geometric configuration.
• the web has apertures facing the shell.
• Fig. 1 discloses a three dimensional view of a quart pot shell structure without the inner walls for better visibility
• Fig. 2 discloses a three dimensional view of an end structure of the pot shell shown in Figure 1 without end wall and deck plate,
• Fig. 3 discloses air flow inside one hollow section of prior art type
• Fig. 4 discloses air flow in accordance with the present invention, through a lower and upper web.
• a quart of a pot shell structure 1 where the steel plates are not shown.
• One half of an end wall 2 and correspondingly one half of a side wall 3 as well as a quart of a bottom 4 haven been disclosed.
• the end wall comprises as its main constituents a deck plate 7, vertical stiffeners 8, 8', 8", 8"', one horizontal web 9 and a reinforcing bracing flange 10.
• the side wall 3 comprises a deck plate 11 , vertical structural elements 6, 6', 6", 6"', 6"", 6""', 6""" which in fact is a part of a cradle structure 12, together with corresponding horizontal beams 5, 5', 5", 5"', 5"", 5""', 5"”” that are fixedly interconnected with the said vertical structural elements. Further, the side wall 3 comprises a plurality of vertical stiffeners 13, 14, 15 which additionally acts as cooling fins.
• Figure 2 discloses in a 3 D view the end wall structure 2 as partly shown in Fig. 1 , here in its full extension and where the deck plate has been removed.
• the reinforcing bracing flange 10 represents the outermost element of the end wall structure.
• the bracing flange is further attached to the side walls and the vertical structural element 6""" of the cradle structure closest to this end.
• the mainly horizontal web 9 which outer periphery fits the shape of the bracing web,
• the end wall structure further comprises vertical stiffeners 8, 8', 8", 8"', 8"", 8"'", 8""".
• the number of stiffeners is a function of the shell width and anticipating inner forces.
• These stiffeners are integrated in the horizontal web 9 by any appropriate manufacturing method.
• the web 9 can have slots adapted to the stiffeners that are subsequently fixed to the web, for instance by welding.
• One other method can be to manufacture the web 9 in appropriate pieces or plates that abut the stiffeners and which subsequently are fixed to the stiffeners.
• the vertical stiffeners are provided with a flange at their outer side. A part of such a flange is indicated at 8a' in stiffener 8', One purpose of this flange is to enhance bending and torsion stiffness in the stiffener with regard to occurring loads.
• the inner side of the stiffener is fixed to the steel plate(s) of the pot shell by appropriate means, for instance welding.
• the stiffeners are connected to an extension of the bottom plate of the shell (not shown), to enhance stiffness in the end wall.
• the horizontal web 9 is provided with several holes or apertures 16, 16', 16", 16"', 16"", 16 , 16 , 16"""'.
• apertures are made sufficiently wide and deep to reduce the presence of the horizontal web with regard to ventilation.
• the apertures are made semi-circular or semi-elliptical or polygonal and are represented by discrete cutouts at the side edge of the web.
• the bridging or protruding parts of the web between neighbouring recesses are connected to the pot shell by appropriate means, for instance welding.
• FIG 2 there can be seen vertical fins 17, 17', 17", 17"', 17"", 17""', 17""", 17'””” passing through corresponding apertures.
• the purpose of the fins is primary to enhance cooling of the pot shell by conductance, but additional effects are guiding the flow of air as well as additional stiffening of the pot shell plates.
• the fins are advantageously fixed to the pot shell by appropriate means such as welding.
• the end wall structure may have two horizontal webs of the type 9 that are spaced apart (not shown).
• FIG. 3 An air flow pattern in accordance with such arrangement is shown in Fig. 3. It can clearly be seen that the air flow is directed upwards along the shell wall and through the ventilation holes or apertures of type 16.

Landscapes

• 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)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

Priority Applications (10)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (12)

Cited By (2)

Families Citing this family (2)

Citations (9)

• 2010
  • 2010-09-03 EA EA201200453A patent/EA021620B1/ru not_active IP Right Cessation
  • 2010-09-03 AU AU2010290196A patent/AU2010290196B2/en active Active
  • 2010-09-03 EP EP10814008.8A patent/EP2475807B1/en active Active
  • 2010-09-03 WO PCT/NO2010/000327 patent/WO2011028132A1/en not_active Ceased
  • 2010-09-03 IN IN1944DEN2012 patent/IN2012DN01944A/en unknown
  • 2010-09-03 NZ NZ598998A patent/NZ598998A/en unknown
  • 2010-09-03 BR BR112012005051-6A patent/BR112012005051B1/pt active IP Right Grant
  • 2010-09-03 CA CA2773127A patent/CA2773127C/en active Active
  • 2010-09-03 NO NO10814008A patent/NO2475807T3/no unknown
  • 2010-09-03 CN CN201080039921.9A patent/CN102549198B/zh active Active
  • 2010-09-06 AR ARP100103263 patent/AR078338A1/es active IP Right Grant
• 2012
  • 2012-03-06 ZA ZA2012/01656A patent/ZA201201656B/en unknown

Patent Citations (9)

Non-Patent Citations (5)

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