JP2009040616A - Castable refractory composition for dry spraying and dry spraying method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the possibility that peeling-off etc. occur in a sprayed body as compared with a conventional method. <P>SOLUTION: This invention provide a castable refractory composition for dry spraying, which comprises (a) a refractory powder, (b) composite fibers obtained by combining at least a first resin and a second resin so that each fiber has in a transverse section a part 11 of the first resin comprising polypropylene or polyester and a part 12 of the second resin having a lower melting point than the first resin constituting the part 11, in an amount of 0.02-1.0 mass% based on 100 mass% of the refractory powder, and (c) a powdery additive containing a binder, wherein a content of water-insoluble particles having a particle diameter of ≤75 μm is confined to ≤30 mass%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a spraying technology for an irregular refractory composition, and in particular, an amorphous refractory composition for dry spraying that can be applied under any temperature condition from cold to hot, and a blowing using the same. It relates to the installation method.

  One of the methods for spraying an irregular refractory composition is a powdered irregular refractory composition to which no construction water is added, which is sent into the transport pipe and air-flow transported, and connected to the transport pipe or the tip of the transport pipe. There is a dry spray construction method in which construction water is added and sprayed in a spray nozzle.

  Also, semi-dry spraying that powdered amorphous refractory composition previously wetted with a small amount of water is sent into the transport pipe and air-flow transported and added with construction water in the transport pipe or spray nozzle The construction method is also known.

  Patent Document 1 discloses a technique that is superior to any of these general dry-type or semi-dry-type spray construction methods. Two sprayers are provided, and a spray construction method is disclosed in which construction water atomized to an average particle size of 100 μm or less is added from each water dispenser to an irregular refractory composition.

  In this specification, whether it is the general dry or semi-dry spraying method described above, or the spraying method of Patent Document 1, the spraying method includes a step of air-flowing the amorphous refractory composition. Is collectively referred to as a dry spraying method.

  The spray construction body constructed by spraying the irregular refractory composition onto the construction surface contains construction water. In the case of hot spraying construction, this construction water is converted into water vapor by the heat of the construction surface, and in the case of cold spraying, by heating when the spraying construction body is dried, Evaporates. At this time, peeling, blistering, or explosion (hereinafter referred to as peeling) may occur in the spraying construction body due to an increase in the internal water vapor pressure of the spraying construction body.

  In order to prevent peeling of the sprayed construction body, it is effective to include organic fibers in the irregular refractory composition. That is, the organic fiber disappears by heat, and a vent hole serving as a water vapor escape path is formed inside the spray construction body. For this reason, the raise of the internal water vapor pressure of a spraying construction body can be relieved, and peeling etc. of a spraying construction body can be suppressed. The following are known as the irregular refractory composition in which peeling or the like is prevented by organic fibers.

  Patent Document 1 discloses a fireproof powder (refractory raw material powder) as an indeterminate fireproof composition for dry spray construction, and an organic fiber having an outer covering of 0.1% by weight based on 100% by weight of the fireproof powder. What consists of a powdery additive containing an agent is disclosed. Examples of organic fibers include vinylon fibers, nylon fibers, and polypropylene fibers. In the examples, vinylon fibers are employed. The amorphous refractory composition contains about 40% by mass of a refractory powder having a particle size of 75 μm or less (see Table 3 of Patent Document 1).

Patent Document 2 discloses a fireproof powder (fireproof aggregate) as an amorphous fireproof composition for dry spray construction, and an organic coating in an amount of 0.01 to 1% by weight with respect to 100% by weight of the fireproof powder. What consists of a fiber and the additive containing a binder is disclosed. Examples of organic fibers include vinylon fibers, polyester fibers, and polypropylene fibers. In the examples, vinylon fibers or polyester fibers are employed. The amorphous refractory composition is made of 25% by mass of sintered magnesia having a particle size of 75 μm or less, 50% by mass of sintered magnesia having a particle size of 1 mm or less, and lightly burned magnesia having a specific surface area of 15 m ² / g or more. 3-12 mass% is contained (refer the Example of Table 1 of patent document 2). Generally, a product having a particle size of 1 mm or less contains at least 10% by mass of a particle size of 75 μm or less, and a particle having a specific surface area of 15 m ² / g or more has a particle size of 75 μm or less. It can be said that the following refractory powder is contained at least 32 mass%.

Patent Document 3 discloses a fireproof powder (basic fireproof material) as an amorphous fireproof composition for dry spray construction, and an organic fiber having a maximum of 3% by mass with respect to 100% by mass of the fireproof powder, What consists of an additive containing a binder is disclosed. Examples of organic fibers include vinylon fibers, polyester fibers, and polypropylene fibers. In the examples, vinylon fibers or polyester fibers are employed. The particle size composition of the refractory powder is not disclosed.
International Publication No. 05/121676 Pamphlet JP-A-9-165272 JP-A-60-71577

  The inventors of the present application select polypropylene fiber among organic fibers as an improvement in the conventional amorphous fireproofing composition for dry spraying disclosed in Patent Documents 1 to 3 and the like, and the amorphous fireproofing composition. A product in which the content of water-insoluble particles having a particle size of 75 μm or less in the entire product was suppressed to less than 20% by mass was filed earlier (see Japanese Patent Application No. 2007-125621).

  Here, the water-insoluble particles refer to particles having a solubility in 100 g of pure water at 20 ° C. of less than 10 g. However, the solubility of the hydrate is represented by the mass of the anhydride dissolved in 100 g of pure water at 20 ° C. For example, refractory powders such as calcined alumina and silica fume, slaked lime, alumina cement and the like are water-insoluble particles. On the other hand, water-soluble particles are particles having a solubility in 100 g of pure water at 20 ° C. of 10 g or more.

  According to the above irregular refractory composition developed by the inventors of the present application, the possibility of delamination or the like in the sprayed construction body is significantly reduced as compared with the conventional ones disclosed in Patent Documents 1 to 3 and the like. However, there has been a demand for a technique that can further reduce the possibility of peeling and the like.

  In addition, the amorphous refractory composition previously developed by the inventors of the present application greatly increases the content of water-insoluble particles having a particle size of 75 μm or less as compared with conventional ones disclosed in Patent Documents 1 to 3 and the like. Therefore, there has been a demand for a technique that can reduce the possibility of peeling or the like in the sprayed construction body without reducing the water-insoluble particles having a particle diameter of 75 μm or less.

  An object of the present invention is to provide an amorphous refractory composition for dry-type spray construction that can reduce the possibility of peeling or the like occurring in the spray-constructed body, and a spray construction method using the same.

  Another object of the present invention is to provide an amorphous refractory composition for dry spray construction that can reduce the possibility of peeling and the like occurring in the spray construction body without reducing water-insoluble particles having a particle size of 75 μm or less. The object is to provide a spray construction method using the above.

  According to one aspect of the present invention, (a) a refractory powder, (b) a portion made of a first resin made of polypropylene or polyester in a cross section, and a first resin constituting the portion. A composite fiber formed by compounding at least the first resin and the second resin so as to have a portion composed of the second resin having a lower melting point than that of the refractory powder. 0.02 to 1.0% by mass and (c) a powdery additive containing a binder, and the content of water-insoluble particles having a particle size of 75 μm or less is reduced to 30% by mass or less by the inner amount. An amorphous fireproof composition for dry spraying that is suppressed is provided.

  According to another aspect of the present invention, the amorphous refractory composition is fed into a transport pipe and air-flow transported, and in the spray nozzle connected to the transport pipe and / or the tip of the transport pipe, the amorphous refractory composition. There is also provided a spray construction method in which the construction water atomized to an average particle size of 100 μm or less is added, and the amorphous refractory composition to which the construction water is added is sprayed from the spray nozzle onto the construction surface.

In this specification, the average particle diameter of the atomized construction water is the volume average particle diameter based on the number measured by the phase Doppler method. The calculation formula is {Σn _i D _i ³ / Σn _i } ^1/3 . Here, n _i is a physical quantity corresponding to the number of particles having a diameter D _i . The value of the volume average particle diameter can be measured using a phase Doppler particle measuring apparatus (model: 2D-PDPA / RSA) manufactured by TSI, USA.

  When using the above-mentioned composite fiber instead of the conventional organic fiber, if the content of the water-insoluble particles having a particle size of 75 μm or less is suppressed to 30% by mass or less, the effect of preventing the sprayed construction from being peeled off may be enhanced. understood. This is because when the content of water-insoluble particles having a particle size of 75 μm or less is suppressed to 30% by mass or less, the effect of improving the linearity of the composite fiber by the portion made of the first resin is from the second resin. This is considered to be due to synergistic effects on the effect of accelerating the disappearance timing of the composite fiber by the portion.

  According to such an irregular refractory composition, a method of adding and spraying construction water atomized to an average particle size of 100 μm or less increases the effect of mixing with construction water, so that spraying with less construction water becomes possible. At the same time, the structure of the spray construction body is tightened well by the impact when sprayed. For this reason, while obtaining the effect of improving the air permeability due to the disappearance of the composite fiber, the apparent porosity of the sprayed construction body can be kept small, and the erosion resistance of the sprayed construction body can be improved. Moreover, since spraying with a small amount of construction water can be realized, the generation of water vapor from the spraying construction body is reduced, and the effect of preventing peeling of the spraying construction body is further improved.

  FIG. 1 shows a schematic view of a dry spray construction apparatus. The powdery amorphous refractory composition 2 in the tank 1 is fed into the transport pipe 5 by the table feeder 3. The amorphous refractory composition 2 fed into the transport pipe 5 is air-transported toward the spray nozzle 4 through the transport pipe 5 on the compressed air supplied from the air introduction pipe 6 into the transport pipe 5. The

  A primary water injector 7 is provided in the middle of the transport pipe 5, and a secondary water injector 8 is provided downstream of the primary water injector 7. The distance along the transfer pipe 5 from the primary water injector 7 to the secondary water injector 8 is about 10 m, and the distance from the secondary water injector 8 to the tip of the spray nozzle 4 is about 0.9 m.

  Each of the primary water injector 7 and the secondary water injector 8 is atomized into the transport pipe 5 to an average particle diameter of 100 μm as measured by a phase Doppler particle measuring device (model: 2D-PDPA / RSA) manufactured by TSI, USA. Construction water is sprayed with compressed air. The actual total amount of construction water sprayed from the primary water injector 7 and the secondary water injector 8, specifically, the average particle diameter of 95% by volume or more is 100 μm.

  Continuously from each of the primary water injector 7 and the secondary water injector 8 under the condition that the amount of construction water added is α mass% (for example, 5 to 15 mass%) as an outer shell with respect to 100 mass% of the amorphous refractory composition. Construction water is sprayed. The primary water injector 7 sprays water in an amount of β mass% (for example, 20 to 30 mass%) of the construction water, and the secondary water injector 8 is 100-β mass% (for example, 70 to 80 mass%) of the construction water. Spray the amount of water. Here, the values of α and β can be appropriately adjusted by a construction worker.

  In the process of flowing through the transport pipe 5, the amorphous refractory composition 2 and the atomized construction water particles are mixed, and the amorphous refractory composition 2 becomes wet. The amorphous refractory composition 2 in a wet state is sprayed onto the construction surface S from the spray nozzle 4 connected to the tip of the transport pipe 5, and a spray construction body 9 is constructed on the construction surface S.

  By atomizing the construction water to an average particle size of 100 μm, the amorphous refractory composition 2 and the construction water are mixed well. For this reason, even if it reduces the usage-amount of construction water compared with the conventional method, it becomes difficult to produce dust and a rebound loss (bounce loss from construction surface S). Moreover, since the structure | tissue of a spraying construction body comes to tighten well with the impact at the time of spraying, the increase in the apparent porosity of the spraying construction body 9 resulting from entraining air can be suppressed.

  Table 1 shows the formulation of the amorphous refractory composition according to the first experimental example. In Table 1, the water-insoluble particles are refractory powder and slaked lime. The electrofused alumina (b) contains 10% by mass of a particle size having a particle size of 75 μm or less. The particle size of calcined alumina, silica fume, and clay is 10 μm or less. The particle size of slaked lime is 6-8 μm. The average length of the PP-PE composite fiber (polypropylene-polyethylene composite fiber) is about 12 mm, and the average diameter is about 0.05 mm.

  Based on the blend G, the blending ratio of the PP-PE composite fiber is not changed, and by adjusting the blending ratio of the fused aluminas (a) to (c) and calcined alumina, a water-insoluble particle size of 75 μm or less The content of the conductive particles was changed in Formulas A to F and H to M.

FIG. 2 is a cross-sectional view of the PP-PE conjugate fiber used in each experimental example in Table 1. The PP-PE composite fiber is composed of a core portion 11 made of polypropylene and polyethylene, specifically, low density polyethylene having a density of 0.929 g / cm ³ or less, in a cross section (cross section perpendicular to the length direction of the fiber). A core-sheath structure having a sheath portion 12 is formed.

  Table 2 shows the composition of the amorphous refractory composition according to the second experimental example. The PP-PE composite fiber of Table 1 has the same average length and average diameter, and the portion corresponding to the core portion 11 of FIG. 2 is made of polyester, and the portion corresponding to the sheath portion 12 is low density. It replaced with the polyester-polyethylene composite fiber (PET-PE composite fiber) which consists of polyethylene, and the structure other than this was made the same as the 1st experiment example.

  Table 3 shows the formulation according to the comparative example. The PP-PE composite fiber in Table 1 is replaced with a non-complexed fiber (PP single fiber) made of polypropylene, which has the same average length and average diameter, and the other configuration is the first. Same as the experimental example.

  Hereinafter, the spray experiment will be described.

  Each of the irregular refractory compositions according to the first and second experimental examples and the comparative example was sprayed onto the construction surface at room temperature using the apparatus shown in FIG. In spraying, the construction worker adjusted the total amount of construction water to be added from the water injectors 7 and 8 in FIG. 1 to be the minimum amount that can suppress dust generation and rebound loss. However, the total amount of construction water and the mass ratio of construction water added from the water injectors 7 and 8 were the same in the first experimental example and the corresponding second experimental example and comparative example. And the apparent porosity and average air permeability of each spray construction body constructed | assembled on the construction surface were measured.

The apparent porosity was measured as follows. The mass after the sample cut out from the spray construction body is dried at 300 ° C. for 24 hours is defined as W ₁ . Next, the sample is submerged in water, boiled for 3 hours, and then allowed to cool to room temperature to obtain a saturated sample, and the mass W ₂ of the saturated sample in water is measured. Then removed water-saturated sample from the water, the mass despite mopped on surface with wet cloth and W _3. The apparent porosity is defined by (W ₃ −W ₁ ) / (W ₃ −W ₂ ) × 100. The apparent porosity means that the smaller the value, the denser the sprayed body and the better the erosion resistance.

The average air permeability was measured as follows. Two rectangular parallelepiped test pieces of the same size are cut out from the sprayed body, one is dried at 110 ° C. for 24 hours, and the other is dried at 300 ° C. for 24 hours, and the respective air permeability Q _{110 ° C.} , Q _{300 ° C.} Measure. The average air permeability is defined by (Q _{110 ° C.} + Q _{300 ° C.} ) / 2. The air permeability is K for the volume of air that permeates the test piece per unit time, S for the surface area of the test piece through which the air passes, L for the thickness of the test piece in the direction through which the air passes, _{U 1} the pressure at the time of air penetration, when the atmospheric pressure was _{U 2,} is defined by _{K × (L / S) /} (U 1 -U 2). The larger the value of the air permeability, the easier it is for the water vapor to escape from the inside of the sprayed construction body to the outside, and the higher the effect of preventing peeling and the like due to the increase of the internal water vapor pressure.

  In FIG. 3, the measurement result of the apparent porosity and average air permeability of each spray construction body in this spraying experiment is shown. The horizontal axis represents the content of water-insoluble particles having a particle size of 75 μm or less in 100% by mass of the amorphous refractory composition. The values on the horizontal axis at the positions of the plots are shown in Tables 1 to 3. The vertical axis on the right side shows the apparent porosity, and the vertical axis on the left side shows the average air permeability.

  The polygonal line P1 shows the fluctuation | variation of the apparent porosity of the spray construction body by the comparative example using PP single fiber. Although there is a slight upward trend, it shows a generally flat trend.

  The broken line G1 shows the fluctuation | variation of the average air permeability of the spray construction body by a comparative example. In a region where the content of water-insoluble particles having a particle size of 75 μm or less is less than about 20% by mass, the average air permeability increases almost in a stepped manner. That is, when the content of the water-insoluble particles having a particle size of 75 μm or less is suppressed to less than 20% by mass, the effect of preventing the sprayed construction from being peeled off is improved.

  Since the water-insoluble particles having a particle size of 75 μm or less become a matrix that fills the gaps between the aggregates, the amount of the water-insoluble particles is a factor that affects both the apparent porosity and the average air permeability. However, in the region where the content of the water-insoluble particles having a particle diameter of 75 μm or less is about 15 to 25% by mass, the variation in the average air permeability (the broken line G1) is taken into account that the variation in the apparent porosity (the broken line P1) is flat. The reason why the non-water-soluble particles having a particle diameter of 75 μm or less fill the gaps between the aggregates is considered to be a cause of the step-like).

  The tendency that the variation of the average air permeability is stepped like the broken line G1 is particularly noticeable when a fiber made of polypropylene is selected among organic fibers. When a single fiber made of polyethylene, vinylon, polyester, or the like is used as the organic fiber, it is difficult to obtain a graph showing fluctuations like the broken line G1.

  Considering the fact that the PP single fiber has a higher elastic modulus representing the resistance to deformation than other organic fibers, the main cause of the change in the average air permeability (folded line G1) in a step shape is the particle size of 75 μm. When the content of the following water-insoluble particles is suppressed to less than 20% by mass, the PP monofilament overcomes the pressure from the matrix surrounding it in the process of flowing through the transport pipe 5 and sprayed while maintaining linearity. It is considered that it can exist in the construction body 9.

  That is, a straight vent hole formed by disappearance of a PP single fiber in a state of maintaining linearity is more air (actually, than a bent vent hole formed by disappearing a bent PP single fiber. Less resistance when water vapor passes. Even if the fiber orientation is the same, the better the linearity of the fiber, the better the air permeability.

  Since water-soluble particles such as phosphates and silicates exist in the process of flowing in the conveying pipe 5 of FIG. 1 or at least dissolved in the construction water in the sprayed construction body, the linearity of the PP single fiber It will not be a factor to prevent. For this reason, the content of the water-soluble particles has little influence on the average air permeability. In order to keep the linearity of the PP single fiber in good condition, it is important to surround the PP single fiber as a matrix and to suppress the content of particles having a particle size of 75 μm or less that greatly affects the linearity. I found out.

  The broken line P2 shows the change in the apparent porosity of the sprayed construction body according to the first experimental example using the PP-PE composite fiber. Similar to the broken line P1, there is a slightly upward trend, but a generally flat trend.

The polygonal line G2 shows the fluctuation | variation of the average ventilation rate of the spraying construction body by a 1st experiment example. In the whole area of the horizontal axis, a value larger than the average air permeability (broken line G1) of the spray construction body according to the comparative example is shown. This is the case of using the PP-PE bicomponent fibers, although the air permeability _{Q 300 ° C.} at 300 ° C. the same value in the case of using PP single fibers, the air permeability _{Q 110 ° C.} is PP single at 110 ° C. This is because it becomes much larger than when fibers are used.

In the case of using PP-PE bicomponent fibers, the Q _{110 ° C.} is larger than in the case of using PP single fibers because the melting point of polypropylene is about 140 to 175 ° C., and the melting point of low density polyethylene is about 90 to 135 ° C. Therefore, at 110 ° C., PP monofilament hardly disappears, but at least a part of the sheath portion made of low-density polyethylene of PP-PE composite fiber disappears, and accordingly, there is a ventilation hole in the sprayed construction body. Is formed.

  By the way, in order to prevent peeling of the sprayed construction body, the earlier the timing at which the organic fibers contained therein disappear, the better. This is because if the timing at which the organic fibers disappear is later than the timing at which the internal water vapor pressure of the sprayed construction body reaches its peak, peeling of the sprayed construction body may not be effectively prevented. The temperature at which the internal water vapor pressure of the spray construction body reaches its peak depends on whether the spray construction body is rapidly heated by the furnace wall during hot construction or in the drying process after the cold construction. In any case, it is preferable that at least a part of the organic fiber disappears at an early stage as much as possible, for example, when the sprayed body reaches 110 ° C.

  In this respect, the sheath part made of low-density polyethylene of the PP-PE composite fiber used in the first experimental example has a timing for the disappearance of the composite fiber earlier than the timing of the disappearance of the PP single fiber. The effect of preventing peeling of the sprayed construction body is higher than when using it.

  On the other hand, the core portion made of polypropylene of the PP-PE composite fiber plays a role of keeping the linearity of the PP-PE composite fiber equal to that of the PP single fiber.

In the region where the content of water-insoluble particles having a particle size of 75 μm or less is less than 20% by mass, the linearity of the PP-PE composite fiber is maintained particularly well by the core portion made of polypropylene. The effect of improving Q _{110 ° C.} by the sheath portion made of low-density polyethylene of the fibers acts synergistically, and the fold line G2 shows a much larger value than the fold line G1.

In the region where the content of water-insoluble particles having a particle diameter of 75 μm or less is 20% by mass or more, it seems that the linearity of the PP-PE conjugate fiber is somewhat lowered. Even if the content of water-insoluble particles having a particle size of 75 μm or less is increased to 30% by mass, the improvement effect of Q _{110 ° C.} by the portion compensates for the decrease in air permeability due to the slight loss of linearity. An average air permeability equal to or higher than that in the case where the content of water-insoluble particles having a particle diameter of 75 μm or less is suppressed to less than 20% by mass using fibers is achieved.

  That is, when using PP single fiber, it was necessary to suppress the content of water-insoluble particles having a particle size of 75 μm or less to less than 20% by mass in order to obtain a good average air permeability. When used, the content of water-insoluble particles having a particle diameter of 75 μm or less may be suppressed to 30% by mass or less. For this reason, the freedom degree of a compounding design improves.

  In addition, in the region where the content of the water-insoluble particles having a particle diameter of 75 μm or less exceeds 30% by mass, the linearity of the fiber is remarkably impaired, or the PP single fiber is used even if the PP-PE composite fiber is used. As in the case, the average air permeability is small.

  The polygonal line P3 shows the fluctuation | variation of the apparent porosity of the spraying construction body by the 2nd experiment example using a PET-PE composite fiber. Similar to the broken lines P1 and P2, there is a slightly upward trend, but a generally flat fluctuation tendency is shown.

  The broken line G3 shows the fluctuation | variation of the average ventilation rate of the spraying construction body by a 2nd experiment example. In the PET-PE composite fiber, the core portion polyester has a higher elastic modulus than the sheath portion low density polyethylene. In addition, the melting point of 90 to 135 ° C. of the low density polyethylene in the sheath part is lower than the melting point of 230 to 260 ° C. of the polyester in the core part. For this reason, in the case of PET-PE composite fibers, as in the case of PP-PE composite fibers, the core portion made of polyester maintains the linearity of the fibers, and the sheath portion made of low-density polyethylene accelerates the disappearance of the fibers.

  The reason why the polygonal line G3 does not change stepwise like the polygonal lines G1 and G2 at the position where the content of water-insoluble particles having a particle diameter of 75 μm or less is 20% by mass is that of the polyester constituting the core part of the PET-PE composite fiber. Since the elastic modulus is inferior to that of polypropylene, a phenomenon occurs in which the linearity of the PET-PE composite fiber is dramatically improved even if the content of water-insoluble particles having a particle diameter of 75 μm or less is suppressed to less than 20% by mass. It is thought that there is not.

  However, the average air permeability (folded line G3) of the spray construction body according to the second experimental example shows a larger value than the average air permeability (fold line G1) of the spray construction body according to the comparative example over the entire horizontal axis. As in the case of the first experimental example, even if the content of the water-insoluble particles having a particle size of 75 μm or less is increased to 30% by mass, the content of the water-insoluble particles having a particle size of 75 μm or less is reduced using PP single fibers. An average air permeability equivalent to that when the content is suppressed to less than 20% by mass is achieved.

  In the region where the content of water-insoluble particles having a particle diameter of 75 μm or less is 20 to 35.1% by mass, the polygonal lines G2 and G3 show similar fluctuation trends. The smaller the content of water-insoluble particles having a particle size of 75 μm or less, the better the average air permeability. Therefore, in the first and second experimental examples, the content of water-insoluble particles having a particle size of 75 μm or less is Based on the position of the plot, it is preferably 27% by mass or less, more preferably 25.6% by mass or less, and even more preferably 22% by mass or less.

  However, in the region where the content of the water-insoluble particles having a particle size of 75 μm or less is less than 15% by mass, the inclinations of the polygonal lines P2 and P3 are slightly abruptly increased. From this, it is considered that the content of the water-insoluble particles having a particle size of 75 μm or less is preferably 15% by mass or more in order to prevent a decrease in the erosion resistance of the sprayed construction body due to an increase in apparent porosity. It is done. Depending on the construction site, erosion resistance may not be required so much, so the content of water-insoluble particles having a particle size of 75 μm or less may be less than 15% by mass.

  As described above, in the first and second experimental examples, low-density polyethylene is used as the second resin to be combined with the first resin made of polypropylene or polyester. However, the second resin is not low-density polyethylene. Polyethylene, for example, medium density polyethylene or high density polyethylene may be used. These melting points are 100 ° C. to 135 ° C., which are slightly higher than those of low-density polyethylene, but lower than the melting points of polypropylene and polyester. Therefore, when these are combined with polypropylene or polyester, the same results as in the above experimental examples can be obtained. I will. In addition, if a resin mainly composed of polyethylene, for example, a resin having a polyethylene content of 80% by mass or more is combined with the first resin, the same result as the above experimental example will be obtained.

  Further, even a resin other than polyethylene has a lower melting point than the first resin, preferably a volume reduction rate at 110 ° C. ((volume at normal temperature−volume at 110 ° C.) / Volume at normal temperature). If the resin is higher than the first resin, the average air permeability can be improved as compared with the case where PP single fiber is used. Examples of the second resin other than polyethylene include a copolymer of ethylene and a comonomer, an aliphatic polyester (eg, polycaprolactone, polybutylene succinate, polyethylene succinate), and the like.

  The second resin has a lower melting point. In order to lower the melting point, it is effective to make an ethylene-vinyl acetate copolymer (EVA) compatible with the base resin. Here, the term “compatible” refers to an operation of mixing already produced polymers. Specifically, a compatible material obtained by compatibilizing an ethylene-vinyl acetate copolymer with polyethylene, preferably low-density polyethylene, has a lower melting point than polyethylene and is preferably used for the second resin. The ratio of the ethylene-vinyl acetate copolymer is preferably 10% by mass or more as an inner portion of the compatible material.

  The composite fiber is not particularly limited to that shown in FIG. For example, in FIG. 2, the sheath portion 12 may be composed of a first resin (eg, polypropylene), and the core portion 11 may be composed of a second resin (eg, low density polyethylene). In short, at least the first portion is formed in the cross section so as to have a portion made of the first resin and a portion made of the second resin having a melting point lower than that of the first resin constituting the portion. It is sufficient that the first resin and the second resin are combined.

  FIG. 4 is a cross-sectional view showing another example of the composite fiber. Hereinafter, for the sake of convenience, a portion made of one of the first resin and the second resin is called a first portion, and a portion made of the other is called a second portion.

  FIG. 4 (a) shows a composite fiber in which a first portion 21 and a second portion 22 each having a semicircular cross section are combined to form a circular cross section.

  FIG. 4B shows a composite fiber in which two first portions 21 and 21 are arranged so as to sandwich the second portion 22 from both sides in a cross-sectional view.

  FIG. 4C is a composite fiber in which the first portion 21 surrounds the second portion 22 and forms a core-sheath structure, as in FIG. 2, and the second portion 22 is eccentric with respect to the first portion. Indicates.

  FIG. 4D shows a core-sheath hollow composite fiber in which a hollow 23 is provided in the core-sheath composite fiber of FIG.

  FIG. 4E shows the relationship between the islands in which the second portion 22 is divided into a plurality of parts, and the first portion 21 is the sea and each of the plurality of second portions 22 is discretely distributed on the sea in a cross-sectional view. As shown, a sea-island type composite fiber obtained by combining the two is shown.

  FIG. 4 (f) shows a sea-island hollow composite fiber in which a hollow 23 is provided in the sea-island composite fiber of (e).

  In Tables 1 and 2, the addition amount of the composite fiber was 0.1% by mass with respect to 100% by mass of the refractory powder, but the addition amount of the composite fiber was 0 with respect to 100% by mass of the refractory powder. It may be 0.02 to 1.0% by mass. If the amount is less than 0.02% by mass, a sufficient number of air holes cannot be formed in the sprayed construction body, so that problems such as peeling of the sprayed construction body cannot be solved. The volume reduction rate of the spray construction body accompanying the disappearance is large, and the construction body tends to warp. Considering the balance between the two problems, the amount of the composite fiber added is preferably 0.04 to 0.3% by mass as an outer coating with respect to 100% by mass of the refractory powder.

  In Tables 1 and 2, although the average length of the composite fiber is 12 mm and the average diameter is 0.05 mm, the average length and the average diameter of the composite fiber are not particularly limited. The average length of the composite fiber is preferably 2 mm to 20 mm, more preferably 2 mm to 13 mm. The average diameter of the composite fiber is preferably 0.01 mm to 1 mm, more preferably 0.025 mm to 0.07 mm.

  The refractory powder is not limited to those shown in Tables 1 and 2. The refractory powder can be composed of a refractory aggregate having a particle size exceeding 75 μm and a refractory fine powder having a particle size of 75 μm or less. Examples of the refractory aggregate include metal oxides such as alumina and bauxite, diaspore, Mullite, kayanite, van shale, chamotte, quartzite, pyrophyllite, sillimanite, andalusite, chromite, spinel, magnesia, zirconia, zircon, chromia, silicon nitride, aluminum nitride, etc., silicon carbide One or more kinds selected from metal carbide, metal, boron carbide, titanium boride, and zirconium boride can be used. Examples of the refractory fine powder include calcined alumina, silica fume, and clay, colloidal silica, Inorganic oxide colloidal particles such as alumina sol can be used.

  The binder is not limited to those shown in Tables 1 and 2. Examples of water-soluble particles include phosphates and silicates, as well as borates. Examples of the water-insoluble particles include alumina cement, magnesia cement, organic matter that forms a carbon bond with heat, such as resin and pitch, and the like. Phosphate or silicate is preferred from the viewpoint of easily ensuring hot air permeability. The addition amount of the binder is preferably 1 to 5% by mass on the basis of 100% by mass of the refractory powder.

The curing accelerator is not limited to those shown in Tables 1 and 2. The water-insoluble particles, besides hydrated _{lime, CaO · Al 2 O 3,} 12CaO · 7Al 2 O 3, CaO · 2Al 2 O 3, 3CaO · Al 2 O 3, 3CaO · 3Al 2 O 3 · CaF 2, Examples thereof include calcium aluminates such as 11CaO · 7Al ₂ O ₃ · CaF ₂ , calcium salts such as calcium oxide, calcium carbonate, and calcium chloride. Examples of water-soluble particles include silicates such as sodium silicate and potassium silicate, aluminates such as sodium aluminate, potassium aluminate and calcium aluminate, sulfates such as sodium sulfate, potassium sulfate and magnesium sulfate, and Examples include calcium chloride. The addition amount of the curing accelerator is preferably 0.1 to 6% by mass as an outer coating with respect to 100% by mass of the refractory powder.

  In addition to binders and curing accelerators, additives include dispersants, sintering aids (eg, metal powders, silicon powders, ferrosilicon powders, etc.), antioxidants such as boron carbide, curing retarders, etc. It may be used.

  The dispersant is selected from water-soluble particles such as sodium citrate, sodium tartrate, sodium polyacrylate, sodium sulfonate, polycarboxylate, β-naphthalenesulfonate, naphthalenesulfonic acid, and carboxyl group-containing polyether. 1 or more types can be used.

  However, it goes without saying that the above materials are combined so that the content of water-insoluble particles having a particle diameter of 75 μm or less in the amorphous refractory composition is 30% by mass or less. When rebound loss increases by carrying out like this, it is good to include the particle | grains which have thickening effects, such as clay, in the water-insoluble particle | grains with a particle size of less than 75 micrometers. Specifically, it is preferable that the clay occupies 3 to 13% by mass, particularly 3 to 8% by mass in 100% by mass of the water-insoluble particles having a particle diameter of less than 75 μm.

  In the experimental examples in Tables 1 and 2, only slaked lime, which is a water-insoluble particle, was used as the curing accelerator, but water-soluble particles may be used as the curing accelerator. If water-soluble particles are used for at least a part of an additive, for example, a curing accelerator, it is possible to easily realize the content of water-insoluble particles having a particle size of 75 μm or less to 30% by mass or less.

  However, what is adopted as the curing accelerator may have to take into consideration compatibility with, for example, that used for the binder. When only water-soluble particles are used as the curing accelerator, if there is a problem with the curing action, water-soluble particles and water-insoluble particles may be used in combination with the curing accelerator. By using both in combination, it is possible to suppress problems when only water-soluble particles are used.

  Moreover, you may melt | dissolve a part or all of a hardening accelerator and a dispersing agent in construction water, and you may spray from the primary water injector 7 and / or the secondary water injector 8 of FIG. In this specification, the construction water is a concept including an aqueous solution of an additive.

  In addition, in this specification, all the water added to an amorphous refractory composition in a conveyance pipe and / or a spray nozzle shall be included in the concept of construction water. The amorphous refractory composition may be moistened with a small amount of water before being fed into the transport pipe, but that water is not included in the concept of construction water.

  Moreover, in the apparatus of FIG. 1, although the substantial whole quantity of construction water was atomized to the average particle diameter of 100 micrometers, the mixing of construction water and an amorphous refractory composition can be improved, so that the average particle diameter of construction water is small. . According to the inventors' research, the average particle diameter of the substantial total amount of construction water is preferably 70 μm or less, more preferably 50 μm or less, and most preferably 30 μm or less.

  Moreover, although the example which supplies construction water in two steps from two water injectors 7 and 8 was shown in FIG. 1, the number of water injectors may be three or more. It will be apparent to those skilled in the art that other various design changes, improvements, and combinations are possible.

  The present invention includes, for example, a blast furnace, firewood, chaos car, converter, snorkel, ladle, secondary refining furnace, tundish, cement rotary kiln, waste melting furnace, incinerator, RH, DH and the like, and It can be used for spraying repair of molten metal containers such as non-ferrous metal containers, molten metal passages, furnaces, or kilns.

It is the schematic of a dry-type spray construction apparatus. It is a cross-sectional view which shows an example of a composite fiber. It is a graph which shows the relationship between content of the water-insoluble particle | grains with a particle size of 75 micrometers or less, the average air permeability of a spraying construction body, and an apparent porosity. It is a cross-sectional view which shows the other example of a composite fiber.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tank, 2 ... Amorphous refractory composition, 3 ... Table feeder, 4 ... Spray nozzle, 5 ... Transfer pipe, 6 ... Air introduction pipe, 7 ... Primary water injector, 8 ... Secondary water injector, 9 ... Blow Application body, S ... construction surface, 11 ... part made of polypropylene (first resin), 12 ... part made of polyethylene (second resin), 21 ... first part, 22 ... second part, 23 ... hollow .

Claims (6)

  (A) refractory powder, (b) a portion made of polypropylene or polyester in the cross section, and a second resin having a melting point lower than that of the first resin constituting the portion. The composite fiber formed by combining at least the first resin and the second resin so as to have a portion composed of 0.02 to 1.0 mass as an outer coating with respect to 100 mass% of the refractory powder. And (c) a powdery additive containing a binder, and the content of water-insoluble particles having a particle size of 75 μm or less is suppressed to 30% by mass or less, and the amorphous refractory composition for dry spraying construction is used. .   The amorphous refractory composition for dry spraying according to claim 1, wherein the content of water-insoluble particles having a particle size of 75 µm or less is 15% by mass or more.   The amorphous refractory composition for dry spraying construction according to claim 1 or 2, wherein the second resin is made of polyethylene or a resin mainly composed of polyethylene.   The amorphous refractory composition for dry spraying construction according to any one of claims 1 to 3, wherein the average length of the composite fiber is 2 mm to 20 mm, and the average diameter is 0.01 mm to 1 mm.   The amorphous refractory composition according to any one of claims 1 to 4, wherein the amorphous refractory composition is fed into a transport pipe and transported by airflow, and the spray fire nozzle connected to the front end of the transport pipe and / or the transport pipe. The spray construction method which adds the construction water atomized to the average particle diameter of 100 micrometers or less to this, and sprays the amorphous refractory composition to which construction water was added to a construction surface from a spray nozzle.   The construction water atomized to an average particle size of 100 μm or less is supplied in multiple stages by a plurality of water injectors arranged at intervals in the transport direction on a transport path constituted by a transport pipe and a spray nozzle. Item 6. The spray construction method according to Item 5.

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