• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Aluminum cells may be provided having cathode surfaces which are wetted by aluminum, said surfaces comprising Refractory Hard Materials in a non-graphitized carbon matrix. Such cells may utilize inclined or drained cathodes as well as non-consumable anodes. The resinous binder system utilized in the surface coating material is characterized by a char yield greater than 25 percent, while the coating composition exhibits expansion characteristics such as to adhere to a cathode block at temperatures up to and including those normally encountered in the operation of an aluminum cell. The ablation rate of the carbon system utilized is essentially equal to the combined wear and dissolution rate of the Refractory Hard Material in an aluminum cell environment.
    公开号:SU1554769A3
    申请号:SU843715907
    申请日:1984-03-21
    公开日:1990-03-30
    发明作者:Джордж Боксалл Ларри；Марк Бачта Вилльям；Викарс Кук Артур；Чарльз Нэгл Деннис；Вилльям Таунсенд Дуглас
    申请人:Коммонвелф Алюминум Корпорейшн (Фирма)；
    IPC主号:
    专利说明:

    This invention relates to non-ferrous metallurgy, in particular to the electrolytic production of aluminum.
    The purpose of the invention is to increase the service life of the cathode by maintaining approximately the dissolution rate of solid refractory and carbon materials in the electrolyzer and ensuring the expansion coefficient of the material of the surface layer is less than 0.2% in the temperature range of 800 ° C.
    The coating composition may be applied to the cathode of the electrolysis cell to produce aluminum as one or
    several layers. A coating system applied in the form of a nonuniform layer can provide a stronger bond due to the greater penetration into the pore structure of the carbon cathode of the first bonding layer, which does not include T1Br, and contributes to easier and faster curing of the coating. In addition, the use of multiple layers can also reduce the size and number of shrinkage cracks in the upper layer containing TiB. According to an embodiment of the invention, the coating composition may comprise up to 10 wt.% Carbon SP
    4 J
    About WITH

    cm
    fiber, which acts as an inhibitor of cracking, as a hardening coating agent, and as an agent that reduces the tendency of the coating to flake off, particularly at any point of contact with the contents of the bath. Carbon cement, which is applied to the cathode substrate as a bonding layer, can contain up to 40% additional carbonaceous filler and additives that prevent cracking of the substrate caused during the curing and carburization of the coating, by increasing the bond strength between the substrate and the bonding agent. layer, as well as improving the properties of the bonding layer.
    The coated cathodes can be successfully used in conventional electrolysis cells to produce aluminum or in electrolytic baths in which the anode and cathode are at an angle to the horizontal. Such constructions demonstrate the advantage of easy removal of aluminum, so that on the cathode surface wetted by aluminum only a thin aluminum film remains, which allows a significant reduction in the distance between the anode and cathode. However, attempts to obtain industrially acceptable inclined cathodes coated on them or on the surface of RHM (refractory hard material) tiles for cathodes have not been successful.
    The invention is applicable to electrolytic cells serving for the electrolytic reduction of aluminum, in which non-consumable anodes are used. Such anodes can consist of a porous material with electronic conductivity, such as platinum black, separated from the molten electrolyte by a ceramic conductive oxygen ion layer that is impermeable to the electrolyte and resistant to it. The oxygen ions pass through the oxide layer and are discharged at the anode to form gaseous oxygen.
    In addition, the proposed electrolyzer may comprise a thinner carbon cathode block as compared to that currently used in conventional, rendered electrolyzers for the production of aluminum. Due to the possibility of increasing the service life of the coating

    in the cathode blocks of large cross section is reduced, resulting in a decrease in the temperature of the electrically conductive medium used, a significant reduction in cost and energy savings. In addition, non-carbon cathode surfaces can be used that are protected by the described surface layer of RHM wetted with aluminum.
    There are certain limits to the temperatures of pre-treatment of the coating composition and cathode blocks. The thickness of the coating can vary from about 0.6 to 1.6 cm or more. Preferred coverage limits are listed in Table 1.
    Table 1
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    Pre-mixing the dry ingredients before mixing the composition
    Preheating the liquid component before mixing the composition. Preheating the cathode blocks prior to coating.
    Coating thickness
    20-45 С
    30-35 ° C
    20-45 С
    40-45 С
    20-65 ° С 40-50 ° С. 0.6-1.6cm 1.0-1.3 cm
    The tendency to form bubbles in the coating depends on the degree and method of treatment of the top surface of the applied wet coating. Main surface finish, either dry or wet machined.
    coating, has a lower tendency to form bubbles compared to a rough, rough surface. The smooth surface contributes to the rapid formation of a film which insulates the surface and prevents the formation of bubbles forming gases which are released during curing. In contrast, non-smooth surface defects promote gas evolution during the curing cycle.
    To obtain a texture characteristic of the machined coatings, a sample of a block of cm-sized coated was taken and placed in an epoxy resin filled with white powder to obtain a white background on a black coating. The sample thus installed was cut and polished so that the surface of the coating could be observed in detail. This cross section was photographed at 12X magnification and the contour of the coating surface was applied to the paper plane. Typical 5 mm sections of this cross section were analyzed on the basis of height (the maximum point is the minimum point) and averaged calculations were performed. Measurement indicators (surface roughness of the coating for the CM-82 coating) are given in Table 2.
    table 2
    Medium point (maximum point - minimum point) on a typical 5 mm segment of the surface
    Without processing1.25
    Handling to a not completely smooth surface. 0.74
    Drying to a completely smooth surface. 0.62 Wet to a completely smooth surface. 0, 26
    Coated cathodes, dry worked until completely smooth0
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    These surfaces, or wet processing to a completely smooth surface, develop to swell, while cathodes that have been processed to a not completely smooth surface exhibit an acceptable coating.
    Below are the compositions of the coatings in accordance with the invention. All components are given in percent by weight, unless otherwise indicated.
    Composition 1, wt.%: 45% - TiB2 in the form of a powder having a particle size approximately less 325 mesh;
    10% carbon additive, which is a VVb graphite aggregate, having a particle size between less than 4 mesh and more than 100 mesh (the BB6 graphite aggregate is manufactured by Union Carbide Corpor);
    0.3% - Fortafil-З (С) - carbon filler, produced by Great hakes Carbon Co,
    19.7% is carbonaceous aggregate, in which 60% is powdered carbon black, and 40% is graphite flour, both of which have a particle size less than 100 mesh;
    25% is a thermoset resinous binder containing 20% furfuryl alcohol, 4% phenol novolac resin, and 1% hexamethylene four-amine catalyst.
    Composition 2, wt.%:
    50% - ZrBz in the form of a powder having a particle size smaller than a mesh;
    15% - carbonaceous additives, representing a graphite aggregate BB6, having a particle size between less than 4 mesh and more than 100 mesh,
    20% carbon filler, in which 60% is powdered carbon black, and 40% is graphite flour, both of which have a particle size of less than / 100 mesh;
    15% - thermosetting resinous binder system, which is a 100% liquid cutting phenolic resin, which is a Varcura product No. 5169, produced by Reickhold Chemicals Inc.,
    Composition 3, wt.%:
    60% - TiC, which has a particle size less than - 100 mesh;
    5% carbon additive, which is graphite. BB6 unit having a particle size
    between less than 4 mesh and more than 100 mesh;
    10% is carbonaceous filler, of which 60% is a black carbon black, and 40% is graphite flour, both of which have a particle size less than
    25% - thermoset binding system based on polyphenylene | Resin, which is Ryton R-4, produced by Phillips Chemical Co.
    Part 4, wt.%:
    20% - which has a particle size of less than 100 mesh;
    9.7% carbon additive, which is a BBB graphite aggregate having a particle size between less than 4 mesh and more than 100 mesh;
    0.3% - Fortafil-З (С) - carbon filler produced by Great hakes Carbon Co.,
    40% carbonaceous aggregate, which is Asbury grade A-99, which is a secondary artificial graphite having a particle size of less than 325 mesh and produced by Asbury Graphite Mil Inc.,
    30% is a reactive binding system based on polybenzimidazole resin.
    Composition 5, mas.%:
    20% TiB, which has a particle size of less than 325 mesh;
    9.6% carbon additive, which is a BBB graphite aggregate having a particle size between less than 4 mesh and more than 100 mesh;
    0.4% - Fortafil-5 - carbon fiber produced by Great hakes Carbon Co .;
    30% carbon filler, which is Asbury grade A-99 and is secondary synthetic graphite having a particle size less than met;
    40% is a thermosetting binder system based on full-resin resin which is Dupont NR-150 B2G produced by E.S. Dupont. Inc.
    Method of preparation.
    Compositions 1-5 were prepared by thoroughly mixing the components at a temperature of 35 ° C. Then each composition was applied using a spatula
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    a depth of about 10 mm to the pre-heated substrate of the cathode block manufactured by Union Carbide Corporation, which was prefaced
    heated at, .35 ° C before applying the composition. The coating with the composition was cured for approximately 24 hours by successively raising the temperature to 165 ° C.
    Following curing, the coating of the composition was carbonized for approximately 36 hours in an inert atmosphere by successively raising the temperature to 1000 ° C.
    Demonstration of equal removal rate.
    Basically, the rate of removal of the solid refractory material (RHM) and the carbonaceous material from the carbonized coating by the composition in accordance with the invention was demonstrated as follows.
    Following drying of the entire coated substrate for each composition, a core sample was cut from the substrate and the applied coating. The core axis was perpendicular to the plane of the coating, and the core radius and its length were approximately equal to 20 and 90 mm, respectively.
    The core was preheated and electrically connected to the negative conductor (cathode) of the direct current source and immersed in a molten bath of industrial electrolyte on a priolite basis, obtained from an active aluminum production electrolyzer. The bath was placed inside a thick-walled graphite crucible that was connected to a positive power source conductor. The core was immersed to a depth of 30 mm in a bath having a total depth of 60 mm and held for 30 minutes without applying current to bring it to equilibrium. Then a current with a density of about 0.01 was passed through the core for about 24 hours. During this time, a metallic product of electrolytic aluminum was formed on the submerged surface of the cathode coating, and it was collected at the bottom of the crucible. After cooling, the metal was recovered and analyzed for solid refractory material content. It was found that it contained a concentration of dissolved solid refractory material in the molten
    aluminum in each composition for a given temperature. Only a small amount of solid refractory material was detected in the metal by scanning electron microscopy on polished samples using ED8 (dispersed energy spectroscopy) and using microwave analysis techniques to identify elements.
    Since it was found that the amount of particles of solid refractory material in each composition is very small, lengthy tests have shown that solid refractory material is lost from the coating due to equilibrium dissolution. If the carbon matrix wears out faster than the solid refractory material, then one would expect the matrix to be eroded around the solid refractory material particles during the tests, as a result of which the solid refractory material will precipitate into the metal. This was not found during prolonged testing for any coating. On the other hand, if particles of solid refractory material wear out faster than the carbon matrix, one would assume that over time all the solid refractory material exposed to molten aluminum metal would dissolve, leaving only the carbon matrix. In this case, as an increasing amount of molten aluminum metal would have been obtained using an electrolyzer, no amount of solid refractory material would be observed in the metal, and one would expect that the analysis for the content of solid refractory material would show a concentration lower than the saturation level. However, an analysis of the content of solid refractory material in the metal for each composition showed that the refractory material is present at approximately the expected level of saturation upon dissolution.
    It can be concluded that the rate of removal of solid refractory material and carbon matrix for each composition is approximately equal.
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    Demonstration expansion.
    Following the curing of each of the compositions 1-5 on the substrate, the pieces of each cured composition were cut off from the substrate. Each of these samples was carbonized for approximately 36 hours by placing each of the samples in a dilatometer with a nitrogen atmosphere and gradually raising the temperature from room temperature to 1000 ° C. The dilatometer is an instrument for measuring expansion. It was found that the expansion of each of the samples as the temperature increased from 800 to 1000 ° C was less than 0.2%.
    权利要求:
    Claims (3)
    [1]
    1. Electrolyzer for electrolytic recovery of aluminum from a clay-clad, supporting anode and cathode made of a substrate and aluminum-wetted surface layer of a hardened carbonized composition of a solid refractory material, mainly titanium diboride, and carbonaceous material,
    Q characterized in that, in order to increase the service life of the cathode by maintaining approximately the dissolution rate of solid refractory and carbon materials from the electrolyzer and providing the coefficient of expansion of the material of the surface layer to less than 0.2% in the temperature range of 800-1000 ° C As a carbonaceous material, it contains a thermosetting resin binder, a carbonaceous filler, and a carbonaceous additive, while the surface layer has components in the following ratio: Oshenii, wt.%:
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    Solid refractory
    material20-60
    Thermoset resin binding 15-40
    Carbon filler 10-40
    Carbon additive additive 5-15
    [2]
    2. Electrolyzer according to claim 1, characterized in that the surface layer contains titanium diboride as a solid refractory material.
    II 1554/6912
    [3]
    3. The electrolyzer according to claim 2, about t l and-5. Electrolyzer according to claim 1, characterized in that, as seen in carbon-solid refractory material, the final filler contains particles of the surface layer contains diboride less than 100 mesh with a C: H ratio of titanium in the form of a single crystal, bicris-5 greater than 2: one. talpa or cluster of single crystals.
    4 "Electrolyzer according to claim 1, about t l and-6. Electrolyzer according to claim 1, characterized in that the thermosetting agent in which the carbonaceous resin binder contains the additive contains carbonic phenolic, furan, polyphenylene particles ranging from -4 mesh to +100 mesh or polyimide resin. And / or carbon fiber.
    i
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    同族专利:
    公开号 | 公开日
    ES539499A0|1985-11-16|
    AU1880883A|1984-02-23|
    CA1256232A|1989-06-20|
    AU571186B2|1988-04-14|
    ES8602156A1|1985-11-16|
    JPH039195B2|1991-02-07|
    NZ204983A|1986-08-08|
    JPS59501671A|1984-10-04|
    ES524394A0|1985-04-16|
    MX159936A|1989-10-06|
    ES8504970A1|1985-04-16|
    WO1984000566A1|1984-02-16|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE1251962B|1963-11-21|1967-10-12|The British Aluminium Company Limited, London|Cathode for an electrolytic cell for the production of aluminum and process for the production of the same|
    US3441529A|1966-11-16|1969-04-29|Union Carbide Corp|Carbonaceous cement|
    US3661736A|1969-05-07|1972-05-09|Olin Mathieson|Refractory hard metal composite cathode aluminum reduction cell|
    US4042656A|1975-04-21|1977-08-16|Vladimir Petrovich Chviruk|Graphite-base filling material for the decomposition of alkali metal amalgams and method of producing same|
    US4179345A|1979-02-26|1979-12-18|Aluminum Company Of America|Controlled wettability graphite electrodes for selective use in electrolysis cells|
    US4308114A|1980-07-21|1981-12-29|Aluminum Company Of America|Electrolytic production of aluminum using a composite cathode|
    US4308115A|1980-08-15|1981-12-29|Aluminum Company Of America|Method of producing aluminum using graphite cathode coated with refractory hard metal|
    US4376029A|1980-09-11|1983-03-08|Great Lakes Carbon Corporation|Titanium diboride-graphite composits|US4582553A|1984-02-03|1986-04-15|Commonwealth Aluminum Corporation|Process for manufacture of refractory hard metal containing plates for aluminum cell cathodes|
    WO1985003532A1|1984-02-03|1985-08-15|Commonwealth Aluminum Corporation|Refractory hard metal containing plates for aluminum cell cathodes|
    DE3885943D1|1987-06-16|1994-01-13|Ucar Carbon Tech|Process for sealing carbon and graphite surfaces.|
    US5019426A|1987-06-16|1991-05-28|Union Carbide Corporation|Topical treatment for sealing carbon and graphite surfaces|
    US5002981A|1988-12-07|1991-03-26|Ucar Carbon Technology Corporation|High strength carbonaceous cement|
    JP5554117B2|2010-03-30|2014-07-23|日本電極株式会社|Cathode carbon block for aluminum refining and method for producing the same|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    US06/400,762|US4544469A|1982-07-22|1982-07-22|Aluminum cell having aluminum wettable cathode surface|
    US06/400,773|US4466996A|1982-07-22|1982-07-22|Aluminum cell cathode coating method|
    US06/400,772|US4526911A|1982-07-22|1982-07-22|Aluminum cell cathode coating composition|
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