JP2010235343A - Graphite-containing filler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a graphite-containing filler which can exhibit superior thermal conductivity while using water and/or alcohol as working liquid. <P>SOLUTION: The graphite-containing filler is prepared by adding water and/or alcohol to a powder composition comprising: graphite of ≥80 mass%; amorphous carbon having an average particle size smaller than that of the graphite of ≥0.1 mass%; and a water-soluble polymer of ≥1 mass%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a graphite-containing filler obtained by adding a working liquid to a powder composition containing graphite and kneading, and particularly relates to a graphite-containing filler using water and / or alcohol as the working liquid.

  Hereinafter, the usage form of the graphite-containing filler will be described by taking the bottom of the blast furnace as an example.

  FIG. 1 is a cross-sectional view of the bottom of the blast furnace. A heat conductive layer 3 is provided below the bottom plate 2 of the iron shell of the blast furnace 1, and a foundation concrete 6 is positioned below the heat insulating layer 5. A cooling pipe 4 is inserted into the heat conductive layer 3. Since the bottom plate 2 is supported by the I-shaped steel beam 7, the load of the blast furnace 1 is not applied to the cooling pipe 4 and the heat conduction layer 3.

  The bottom of the blast furnace 1 is cooled through the heat conduction layer 3 by the cooling water flowing in the cooling pipe 4. In order to perform cooling efficiently, it is desired that the heat conductive layer 3 has good heat conductivity. Therefore, graphite, which is a material having good thermal conductivity, is used for the heat conductive layer 3.

  The heat conductive layer 3 is formed as follows. First, a graphite stamp material is driven and installed around the cooling pipe 4. Since the dimensional accuracy is not good because of the driving construction, and the area of the bottom plate 2 is extremely large, the heat conductive layer 3 does not adhere to the bottom plate 2 and a gap may be formed between the two depending on the location.

  The presence of such voids is a factor that hinders heat transfer from the blast furnace 1 to the cooling pipe 4. Therefore, in order to prevent the formation of voids, a gap of about several millimeters is intentionally formed between the bottom plate 2 and the heat conductive layer 3, and a graphite-containing filler is press-fitted into the gap.

  The graphite-containing filler is prepared by adding a working liquid to a powder composition containing graphite. The graphite-containing filler is roughly classified into an aqueous system using water as a construction liquid and a non-aqueous system using liquid resin, tar, and / or pitch.

  When the non-aqueous graphite-containing filler is applied between the bottom plate 2 and the heat conductive layer 3, the construction liquid is absorbed into the heat conductive layer 3 and fluidity is lost. There is a report that there is a problem that the gap is not densely filled (see Patent Document 1). In addition, non-aqueous graphite-containing fillers have drawbacks such that fluidity is easily influenced by the outside air temperature, and poor filling is likely to occur during construction in winter.

  For this reason, it is desirable to use an aqueous graphite-containing filler between the bottom plate 2 and the heat conductive layer 3 in FIG. Conventionally, those disclosed in Patent Documents 1 and 2 are known as water-based graphite-containing fillers.

  Patent Document 1 discloses an aqueous graphite-containing filler obtained by adding water and kneading a powder composition containing graphite in an amount of 10 to 30% by mass with the balance being mainly silicon carbide.

  Patent Document 2 discloses an aqueous graphite-containing filler obtained by adding water and kneading a powder composition comprising graphite: 60% by mass and clay: 40% by mass (Patent Document 2). See Table 1, Formulation Example 1).

  Although not a graphite-containing filler, those disclosed in Patent Documents 3 and 4 are known as containing graphite and water.

  Patent Document 3 discloses a lubricant dispersion in which graphite: 50 to 95% by mass and 5 to 50% by mass of a water-soluble polymer are dispersed in water.

  Patent Document 4 discloses a black aqueous ink containing graphite and a water-soluble polymer.

JP 2008-156133 A JP-A-53-133217 JP 58-47097 A JP 2005-162792 A

  The water-based graphite-containing filler has a problem that it is difficult to knead the powder composition without separating it from the construction liquid because the graphite is difficult to wet with water.

  In this regard, Patent Document 1 explains that graphite is poor in wettability with water, but if the proportion of graphite in the powder composition is suppressed to 30% by mass or less, kneading with water becomes possible. Patent Document 2 explains that kneading with water becomes possible if clay is used in combination.

  However, as disclosed in Patent Documents 1 and 2, conventional water-based graphite-containing fillers can be used in combination with many graphites having a low thermal conductivity, such as clay and silicon carbide, which are inferior to graphite. Since it is essential, it is difficult to obtain good thermal conductivity as a whole filler.

  The inventors of the present application have found that if a water-soluble polymer is used, the separation of graphite during kneading can be prevented even if water is used as the construction liquid. Patent Documents 3 and 4 disclose a combination of graphite and a water-soluble polymer. However, simply combining graphite and a water-soluble polymer is insufficient for improving thermal conductivity.

  The objective of this invention is providing the graphite containing filler which can show the outstanding heat conductivity, using water and / or alcohol for a construction liquid.

  According to one aspect of the present invention, graphite: 80% by mass or more, amorphous carbon having an average particle size smaller than the graphite: 0.1% by mass or more, and water-soluble polymer: 1% by mass or more. There is provided a graphite-containing filler obtained by adding water and / or alcohol to a powder composition and kneading.

  By using 1% by mass or more of the water-soluble polymer, it is possible to prevent the graphite from being separated at the time of kneading even if water and / or alcohol is used for the construction liquid. For this reason, most of the powder composition, specifically, 80% by mass or more can be composed of graphite.

  In addition, amorphous carbon having an average particle size smaller than that of graphite is interposed between graphite particles and has an effect of promoting heat conduction between graphite particles. This effect is manifested when 0.1% by mass or more of amorphous carbon is added. Amorphous carbon has a smaller anisotropy than graphite, and therefore can ensure the effect of increasing the thermal conductivity between graphite particles.

  As a result, excellent thermal conductivity can be exhibited as a whole filler.

It is sectional drawing of the furnace bottom part of a blast furnace. It is sectional drawing around the stave cooler in the furnace wall part of a blast furnace.

  As the graphite, for example, one or more selected from artificial graphite such as natural graphite such as scaly graphite and earthy graphite, and a crushed material for steelmaking electrodes (so-called electrode scrap) can be used. Of these, scaly graphite is preferred because of its high crystallinity and excellent thermal conductivity.

  Among graphite, scaly graphite has great anisotropy, and therefore, particularly when scaly graphite is used as graphite, it is significant to relax the anisotropy of scaly graphite by using amorphous carbon together.

  From the viewpoint of obtaining a good workability in combination with a water-soluble polymer and amorphous carbon, graphite preferably has a broad particle size distribution. Specifically, graphite has a particle size of less than 0.15 mm: 3% by mass or more, a particle size of 0.15 mm or more and less than 0.21 mm: 20% by mass or more, and a particle size of 0.21 mm or more and less than 0.3 mm: 20% by mass. It is preferable that the particle size is not less than 0.3 mm and not less than 10% by mass.

  In the present specification, the particle size of the particle being less than d means that the particle has a particle size passing through a sieve having an opening d defined in JIS-Z8801, and the particle size of the particle is d or more. It means that the particles have a particle size remaining on the same sieve.

  As the amorphous carbon, for example, one or more selected from carbon black, carbon whisker, coke, anthracite, coal powder, carbon brick waste and the like can be used.

  The average particle diameter of amorphous carbon is not particularly limited as long as it is smaller than that of graphite. For example, when the average particle diameter of graphite is 75 to 300 μm, the average particle diameter of amorphous carbon is preferably 0.1 μm or less.

  In this specification, the average particle diameter means the volume average particle diameter corresponding to the central cumulative value (D50) of the cumulative curve measured with a laser diffraction / scattering particle size distribution meter.

  Examples of the water-soluble polymer include methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, hydroxypropyl cellulose, polyethylene oxide, polyacrylamide, sodium polyacrylate, lignin sulfonate, maleic anhydride-isobutylene copolymer, One or more selected from sodium alginate, ammonium alginate, dextrin, sun gum, karaya gum, locust bean gum, xanthan gum, gum arabic, yam starch, taro starch, mung bean starch, rice starch, corn starch, and other starches can be used. .

  The water-soluble polymer preferably has a viscosity in a 2% by mass aqueous solution (hereinafter also simply referred to as a viscosity of the water-soluble polymer) of 1 to 10 Pa · s. When the viscosity of the water-soluble polymer is 1 Pa · s or more, dripping does not easily occur and good workability is easily obtained. When the viscosity of the water-soluble polymer is 10 Pa · s or less, the interparticle distance of the graphite is prevented from increasing, and it contributes to obtaining good thermal conductivity.

  In this specification, the viscosity refers to a measured value at 30 rpm using a B-type viscometer when the fluid to be measured is 20 ° C.

  Water and / or alcohol is used as the construction liquid. As alcohol, monohydric alcohols, such as methanol and ethanol, are preferable. The addition amount of the construction liquid is appropriately determined according to the construction form of the graphite-containing filler. For example, the plasticity which can be press-fit and apply | coated to a filler can be provided by setting it as 10-50 volume% by the outer coating with respect to 100 volume% of powder compositions.

  In this specification, the amount (volume%) of the construction liquid added to the powder composition is calculated based on the loosened bulk of the powder composition. The loose bulk refers to the volume occupied by the target powder when the target powder is gently poured into the container.

  Hereinafter, the use of the graphite-containing filler of the present invention will be described.

  The graphite-containing filler of the present invention can be preferably used, for example, between the bottom plate 2 which is a part of the iron shell of the blast furnace 1 in FIG. 1 and the heat conductive layer 3 below the bottom plate 2. Since the graphite-containing filler of the present invention is excellent in thermal conductivity, the thermal resistance from the bottom plate 2 to the heat conductive layer 3 can be reduced, and the cooling efficiency of the furnace bottom portion by the cooling pipe 4 can be increased.

  In addition, after applying the graphite containing filler of this invention between the baseplate 2 and the heat conductive layer 3 of FIG. 1, this is normally heat-dried. In the blast furnace, the refractory lining does not oxidize with water vapor, so water-based graphite-containing fillers are not normally used. However, if the refractory is used outside the iron skin, such as the lower part of the bottom plate 2 in FIG. The problem of steam oxidation of refractories is unlikely to occur.

  Based on the above, according to the first specific embodiment of the present invention, it was constructed as constituting at least a part of a heat transfer path from a blast furnace furnace body or other cooling object to a cooling pipe or other cooling means. Thereafter, the graphite-containing filler used after being heated and dried is provided.

  In addition, the graphite-containing filler of the present invention can be used in an undried state as long as it is in an enclosed state capable of preventing the escape of the working liquid even inside the blast furnace iron skin. Conventionally, the technical idea of using an aqueous graphite-containing filler in an encapsulated state without heating and drying is not known.

  Hereinafter, an example of using the graphite-containing filler in an encapsulated state will be described.

  FIG. 2 is a sectional view around the stave cooler in the furnace wall of the blast furnace. The stave cooler 10 includes a heat receiving plate 13 attached to the iron skin 12 via an irregular refractory 11 and a cooling pipe 14 that is inserted into the heat receiving plate 13 and through which cooling water flows. The furnace wall is cooled through the heat receiving plate 13 by the cooling water flowing in the cooling pipe 14.

  A graphite-containing filler 15 is enclosed between the heat receiving board 13 and the cooling pipe 14. Encapsulation of the graphite-containing filler 15 can be realized, for example, by covering an exposed portion of the graphite-containing filler 15 on the surface of the heat receiving board 13 with a sealing material 16 such as silicone and / or an amorphous refractory 11. .

  By placing the graphite-containing filler 15 in an encapsulated state, the heat conductivity of water and / or alcohol itself in the graphite-containing filler 15 is utilized, so that the heat conduction is superior to that of a non-aqueous graphite-containing filler. May show gender. That is, water and alcohol have higher thermal conductivity than non-aqueous construction liquids such as liquid resin, tar, and pitch. For this reason, the furnace wall can be efficiently cooled by the cooling pipe 14.

  Based on the above, according to the second specific embodiment of the present invention, the construction liquid is assumed to constitute at least a part of the heat transfer path from the blast furnace furnace body or other cooling object to the cooling pipe or other cooling means. The above graphite-containing filler used in an encapsulated state in an undried state is provided.

  Table 1 shows the composition of the graphite-containing filler and the evaluation results. The amount of water-soluble polymer added was fixed at 1% by mass, and the amount of carbon black added as amorphous carbon was varied to investigate the relationship with thermal conductivity.

  In Table 1, the scaly graphite has a particle size of less than 0.15 mm: 7% by mass or more, a particle size of 0.15 mm or more and less than 0.21 mm: 30% by mass or more, and a particle size of 0.21 mm or more and less than 0.3 mm: 30% by mass. % Or more and a particle diameter of 0.3 mm or more: an average particle diameter of 15 μm or more was used having a particle diameter of 200 μm. Carbon black having an average particle size of 0.03 μm was used. As the water-soluble polymer, methylcellulose having a viscosity of 3 to 5.5 Pa · s in a 2% by mass aqueous solution was used.

  The post-drying thermal conductivity index is a value obtained by dividing the thermal conductivity of the filler of each example by heating at 110 ° C. for 24 hours by the thermal conductivity after drying in Example 3 and multiplying by 100.

  The thermal conductivity index before drying is a value obtained by dividing the thermal conductivity in the undried state of the filler of each example by the thermal conductivity in the undried state of Example 3 and multiplying by 100.

  As shown in Table 1, when the addition amount of carbon black is 0.1% by mass or more, the effect of the addition appears in the dry state and the undried state, and the thermal conductivity is improved. In order to exhibit the effect of the addition of carbon black, it is necessary to add 0.1% by mass or more.

  However, if the amount of carbon black added exceeds 2% by mass, the proportion of scaly graphite decreases accordingly, or the thermal conductivity tends to decrease both in the dry state and in the undried state. From the results of Table 1, it is considered that the addition amount of carbon black and other amorphous carbon is preferably 0.1 to 2% by mass.

  From the viewpoint of improving thermal conductivity, the proportion of graphite in the powder composition is preferably as high as possible. As described above, the amount of amorphous carbon added is preferably 0.1 to 2% by mass, and the amount of water-soluble polymer added is about 10% by mass, which is sufficient for preventing the separation of graphite. The powder composition is preferably composed of graphite: 88 to 98.9% by mass, amorphous carbon: 0.1 to 2% by mass, and water-soluble polymer: 1 to 10% by mass.

  Table 2 shows other blending configurations and evaluation results of the graphite-containing filler. The relationship between the viscosity of the water-soluble polymer used and the amount of water added, and the thermal conductivity and workability was investigated.

  In each example of Table 2, water is added and kneaded into a powder composition consisting of scaly graphite: 94% by mass, carbon black: 1% by mass, and methylcellulose as a water-soluble polymer: 5% by mass. Become. The same scale graphite and carbon black as those used in Table 1 were used.

  The thermal conductivity after drying was evaluated in three stages, with the thermal conductivity index after drying defined in Table 1 being 90 or more, ◯ when 85 or more and less than 90, and △ when 80 or less than 85. .

  Similarly, the thermal conductivity before drying is classified into three stages, where the thermal conductivity index before drying defined in Table 1 is 90 or more, ◯ is 85 or more and less than 90, and △ is 80 or more and less than 85. evaluated.

  Regarding workability, Examples 9 to 14 and 16 were particularly good. In Examples 7 and 8, although the water-soluble polymer has a low viscosity, it is acceptable but the workability is somewhat difficult. That is, Example 7 is inferior in adhesion to the construction surface and shape retention, and Example 8 tends to be slightly dropped from the construction surface. Example 15 is acceptable, although the viscosity of the water-soluble polymer is somewhat high due to the relationship with the amount of water added, but is somewhat high.

  Regarding the thermal conductivity, Examples 7 to 15 were particularly good. Example 16 is acceptable but relatively poor in thermal conductivity in the undried state. This is because the viscosity of the water-soluble polymer used is relatively high and the amount of water added is relatively large, so the tendency for the graphite particles to exist apart in the structure of the filler has increased. It is guessed.

  From the results shown in Table 2, when considering the workability and the thermal conductivity after drying and before drying, the viscosity of the water-soluble polymer is 1 to 10 Pa · s when the addition amount of the working liquid is 10 to 50% by volume. It can be said that 1 to 5.5 Pa · s is more preferable.

  Table 3 shows still other blending configurations and evaluation results of the graphite-containing filler.

  In Table 3, the same materials as those shown in Table 1 were used for the scaly graphite, carbon black, and water-soluble polymer. As the alcohol, an aqueous ethanol solution having a concentration of 50% by mass was used. The definitions of the thermal conductivity index after drying and the thermal conductivity index before drying are the same as those in Table 1.

  In Examples 17 and 18, although water and / or alcohol was used as the construction liquid, the proportion of graphite in the powder composition was increased to 88% by mass by using a water-soluble polymer. Since it became possible, the thermal conductivity was remarkably superior to that of Example 19 corresponding to the conventional water-based graphite-containing filler in both the dry state and the undried state.

  In Examples 17 and 18, since the heat conductivity of water and / or alcohol as the construction liquid is fully utilized in the undried state, the heat conductivity equivalent to Example 20 which is a non-aqueous graphite-containing filler is used. Achieved sex.

  As mentioned above, although the specific example of this invention was demonstrated, this invention is not limited to this. For example, it will be apparent to those skilled in the art that various combinations and improvements are possible.

  The graphite-containing filler of the present invention is preferably used in a dry state or an undried state as constituting at least a part of a heat transfer path from a blast furnace furnace body or other cooling object to a cooling pipe or other cooling means. In addition, the effect of increasing the cooling efficiency of the object to be cooled by the cooling means can be exhibited by reducing the thermal resistance in the heat transfer path. The graphite-containing filler of the present invention can be particularly preferably used for blast furnace construction including a blast furnace bottom, a furnace wall, and a stave cooler.

  DESCRIPTION OF SYMBOLS 1 ... Blast furnace, 2 ... Bottom plate, 3 ... Heat conductive layer, 4 ... Cooling pipe, 5 ... Thermal insulation layer, 6 ... Foundation concrete, 7 ... I-type steel beam, 10 ... Stave cooler, 11 ... Unshaped refractory, 12 ... Iron Leather, 13 ... heat receiving board, 14 ... cooling pipe, 15 ... graphite-containing filler, 16 ... sealing material.

Claims (1)

  A powder composition comprising graphite: 80% by mass or more, amorphous carbon having an average particle size smaller than that of the graphite: 0.1% by mass or more, and water-soluble polymer: 1% by mass or more, water and / or Or the graphite containing filler formed by adding and kneading alcohol.

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