Hot dry spraying material and hot dry spraying method
Technical field
[0001]
　TECHNICAL FIELD The present invention relates to a hot-type dry spray material (unshaped refractory material) which is preferably used for hot repair of an industrial kiln such as a molten steel ladle and a furnace body (furnace wall) of an electric furnace, and a construction method thereof.
Background technology
[0002]
　Amorphous refractories have different construction methods depending on the intended use. For example, when an amorphous refractory material is used as a castable material for lining an industrial kiln, the refractory material and water are kneaded, poured, cured, and dried.
[0003]
　On the other hand, there is also a case where an amorphous refractory is used as a spraying material for construction or repair of an industrial kiln. In this case, the construction method is roughly classified into a wet spray construction method and a dry spray construction method. In the wet spraying method, the spraying material and water are sufficiently kneaded in advance by a mechanical kneading mechanism such as a mixer, and the kneaded product is pressure-fed toward the spraying nozzle by a pump, and the tip of this spraying nozzle is used. It is a construction method in which air and a quick-setting agent are introduced and sprayed. The dry spraying construction method is a construction method in which water is added to a dry powdery spray material at the tip of the spray nozzle and sprayed without using a mechanical kneading mechanism.
[0004]
　Generally, spraying using a spray material is performed in both hot and cold environments, and the dry spraying method is applied in both environments. However, the wet spraying construction method is generally not applied in a hot environment. This is because, in the case of the wet spraying construction method, since the kneading work is required in advance, post-cleaning work such as cleaning work of the transfer hose used when pressure-feeding with a kneading machine or pump occurs after the construction. Therefore, the wet construction method is not suitable for spraying construction in a hot environment, and a dry spraying construction method, which is a simple construction method, is often applied.
[0005]
　The spraying material used in this dry spraying method (irregular refractory for dry spraying) is the adhesion between the spraying material and the construction surface during spraying, and the spraying material after the industrial kiln is operated after spraying. It is necessary to improve the adhesion to the work surface and the corrosion resistance of the sprayed material.
[0006]
　As an amorphous refractory for dry spraying, Patent Document 1 discloses a spraying material containing magnesia limestone. However, when the present inventors carried out hot spraying using a spraying material containing magnesia limestone, there were cases where the adhesiveness, adhesiveness and corrosion resistance were not sufficient.
Advanced technical literature
Patent literature
[0007]
Patent Document 1: JP-A-58-145660
Summary of the invention
Problems to be Solved by the Invention
[0008]
　The problem to be solved by the present invention is to improve the adhesion, adhesiveness and corrosion resistance in the hot dry spraying material and the hot dry spraying method.
Means for solving the problem
[0009]
　According to one aspect of the present invention, the following hot-type dry spray material is provided.
“A hot dry spraying material containing a refractory material and a binder, containing
　10% by mass or more and 50% by mass or less of magnesia limestone having a particle diameter of 1 mm or more in 100% by mass of the refractory material and the binder. A
　hot dry spray material obtained by adding 10% by mass or more and 50% by mass or less of water to the total amount of the refractory material and the binder of 100% by mass.”
[0010]
　According to another aspect of the present invention, the following hot dry spraying method is provided.
``A compound containing a refractory material and a binder is pressure-fed toward a spray nozzle through a pipe, and in the hot dry spraying construction method of adding water at the tip of the spray nozzle and spraying hot, the
　compound is, In 100 mass% of the total amount of the refractory material and the binder, 10 mass% or more and 50 mass% or less of
　magnesia limestone having a particle diameter of 1 mm or more is included, and the amount of water added is the total amount of the refractory material and the binder. A hot dry spraying construction method in which 10% by mass or more and 50% by mass or less are applied to 100% by mass."
Effect of the invention
[0011]
　According to the present invention, adhesion, adhesiveness and corrosion resistance can be improved by setting the content of magnesia limestone and water of 1 mm or more within a specific range. Specifically, as an effect of improving the adhesiveness and the adhesiveness, water volatilizes first to generate open pores in the sprayed material construction body, and thereafter, magnesia limestone having a particle size of 1 mm or more is decomposed to generate carbon dioxide gas. Are generated, and open pores are generated by this carbon dioxide gas. That is, a quick-drying property is obtained by generating a path that penetrates the construction body in two steps. As a result, dehydration from the interface between the construction body (spray material) and the construction body is promoted, and the adhesion and adhesiveness are improved.
Brief description of the drawings
[0012]
FIG. 1 is an explanatory view showing a method of evaluating adhesiveness.
MODE FOR CARRYING OUT THE INVENTION
[0013]
　The dry spraying material for hot use of the present invention contains 10% by mass or more and 50% by mass or less of magnesia limestone having a particle diameter of 1 mm or more in 100% by mass of the refractory material and the binder (hereinafter referred to as “total amount”). The total amount of 100 mass% is externally added with 10 mass% or more and 50 mass% or less of water.
[0014]
Magnesium 　limestone (CaCO 3 ·MgCO 3 ) having a particle size of 1 mm or more produces carbon dioxide (CO 2 ) by the decomposition reaction of the following formula (1) .
　CaCO 3 ·MgCO 3　→CaO·MgO+2CO 2　(1)
　This decomposition reaction starts at about 600° C. and ends at about 800° C. Therefore, when the hot dry spraying material of the present invention is hot-sprayed, as described above, water volatilizes first to generate open pores in the sprayed material, and thereafter, the hard-grid having a particle size of 1 mm or more is added. Limestone is decomposed to generate carbon dioxide gas, and this carbon dioxide gas generates open pores. As a result, the adhesiveness and adhesiveness can be improved. The term "hot" refers to an environment in which the temperature of the work surface is approximately 600°C or higher.
[0015]
　When the content of magnesia limestone having a particle size of 1 mm or more is less than 10% by mass, the effect of improving the adhesiveness and the adhesiveness cannot be sufficiently obtained. On the other hand, when the content of magnesia limestone having a particle size of 1 mm or more exceeds 50% by mass, the carbon dioxide gas generated by the decomposition reaction becomes too large, and the adhesion and the adhesiveness are deteriorated. In addition, the number of pores generated by carbon dioxide gas increases and the corrosion resistance also decreases. The content of magnesia limestone having a particle diameter of 1 mm or more is preferably 20% by mass or more and 40% by mass or less in 100% by mass in total.
[0016]
　The hot dry spray material of the present invention may contain magnesia limestone having a particle size of less than 1 mm. However, if a large amount of magnesia limestone with a particle size of less than 1 mm is included, a decomposition reaction (formula (1)) of magnesia limestone with a particle size of less than 1 mm will occur immediately after attachment to the work surface, and this decomposition reaction will occur. Due to the hydration reaction of CaO (formula (2) below), Ca 2+ is eluted in the construction body . As a result, the viscosity of the slurry-like construction body is increased at an early stage, there is a concern that the wettability to the construction surface cannot be ensured and the construction body is cured to lower the adhesion. Therefore, the content of magnesia limestone having a particle size of less than 1 mm is preferably 25% by mass or less (including 0) in the total amount of 100% by mass.
　Tasu 2H CaO 2 O ￫ Ca 2Tasu Tasu 2OH　- ... (2)
[0017]
　In the present invention, the amount of water added at the time of spraying is 10% by mass or more and 50% by mass or less by external coating with respect to the total amount of 100% by mass as described above. If the amount of water added is less than 10% by mass, the spray material and water are not sufficiently mixed and spraying cannot be established. Also, during hot work, the amount of water is small and the water evaporates quickly, so heat is easily transferred to the construction body, and the decomposition reaction of magnesia limestone with a particle size of 1 mm or more proceeds too quickly, resulting in the generation of carbon dioxide gas too quickly. Therefore, the adhesiveness and the adhesiveness are lowered.
　On the other hand, when the amount of water added exceeds 50% by mass, excessive open pores are generated due to open pores generated by volatilization of water and open pores due to carbon dioxide gas generated from magnesia limestone having a particle size of 1 mm or more. As a result, corrosion resistance decreases.
　It is preferable that the amount of water added is 20% by mass or more and 40% by mass or less by external multiplication with respect to the total amount of 100% by mass.
[0018]
　The hot dry spray material of the present invention, as a refractory material other than magnesia limestone, may include various refractory materials that are commonly used in spray materials, the main component of which considers compatibility with magnesia limestone. It is preferable to use a basic refractory material (basic oxide) such as magnesia, olivine (olivine), and used magnesia carbonaceous brick scraps. Refractory materials other than basic refractory materials may include alumina and the like.
[0019]
　As the binder, those commonly used in dry spraying materials can be used as the binder, and examples thereof include silicates such as sodium silicate, phosphates, pitches, powder resins, and alumina cement. Further, the amount (content) of the binder used may be the same as that of a general dry spraying material, and is, for example, 1% by mass or more and 10% by mass or less in 100% by mass in total.
[0020]
　Moreover, you may use an additive for a binder. As the additive, various additives such as a curing agent, a dispersant and a thickener can be used. For example, slaked lime can be used as a hardening agent, phosphate as a dispersant, and clay as a thickener.
[0021]
　The hot dry spray material of the present invention as described above, the composition containing the refractory material and the binder as described above is pressure-fed toward the spray nozzle through the pipe, and water is added at the tip of the spray nozzle. It is used for the hot dry spraying method.
Example
[0022]
　Tables 1 and 2 show the material configurations and evaluation results of Examples and Comparative Examples of the hot dry spraying material of the present invention. In Tables 1 and 2, the "other" binder is clay, slaked lime, dispersant, or the like.
　The evaluation items and evaluation methods are as follows.
[0023]

　The hot dry spray material of each example was sprayed from the spray nozzle at a spray rate of 15 kg/min toward the surface of the magnesia brick heated to 1000° C. as the construction surface for 1 minute. At this time, the amount of water added at the tip of the spray nozzle was the amount shown in each example of Table 1 and Table 2. That is, the "addition amount of water" shown in Table 1 and Table 2 indicates the addition amount of the external product with respect to the total amount of 100% by mass.
　By performing the spraying for 1 minute, a sprayed construction body including a construction body of the sprayed material having a thickness of about 50 mm was obtained. A sample of a predetermined size cut out from this sprayed structure was eroded at 1650 to 1700° C. for 3 hours using a rotary erosion tester with a C/S=3.5 converter slag as an erosion agent. The maximum amount of erosion in each example was measured, and the relative amount with the maximum amount of erosion in Example 1 as 100 was determined. When the relative amount was 100 or less, ⊚ (excellent), when it was more than 100 and less than 110, it was evaluated as ◯ (good), and when it was more than 110, it was evaluated as × (impossible).
[0024]
In
　the sprayed construction body of each example obtained in the above manner, the shear stress between the construction body of the sprayed material and the magnesia brick was measured, and the relative value with the shear stress of Example 1 as 100 was determined. When the relative value was 100 or more, it was evaluated as ⊚ (excellent), when it was more than 70 and less than 100, it was evaluated as ◯ (good), and when it was 70 or less, it was evaluated as x (impossible).
[0025]
As
　shown in the upper part of FIG. 1, a yokan-shaped magnesia brick is provided with a space of 15 mm in the center, and water is added to the spray material of each example in an amount corresponding to the amount of water added and kneaded. After being cast, cured and dried, a test piece was obtained by firing at 1400° C. for 3 hours with a load of 0.25 MPa applied from the tip of the yokan as shown in the lower part of FIG. The bending strength of the adhesive surface of the test piece of each example was measured by a three-point bending test, and a relative value was obtained with the bending strength of Example 1 being 100. When the relative value is 100 or more, ◎ (excellent) When the value was more than 60 and less than 100, the evaluation was good (good), and when the value was 60 or less, it was x (impossible), and the evaluation was performed in three levels.
　The evaluation of the adhesiveness is an index representing the adhesive strength between the sprayed material and the surface to be worked after the industrial kiln is operated after the spraying in the actual spraying.
[0026]
In
　each of the above-mentioned evaluations, ◎ (excellent) when ◎ is 2 or more, ○ (good) when ◯ is 2 or more, × when any one is × or when measurement is impossible. It was evaluated as 3 (Failure). This comprehensive evaluation is an index showing the durability of the actual sprayed construction body.
[0027]
[Table 1]

[0028]
[Table 2]

[0029]
　Examples 1 to 11 shown in Table 1 are hot dry spraying materials within the scope of the present invention. In each case, the overall evaluation was ⊚ (excellent) or ∘ (good), and good results were obtained.
[0030]
　Comparative Example 1 in Table 2 is an example in which the content of magnesia limestone having a particle size of 1 mm or more is small. The effect of improving the adhesiveness and the adhesiveness was not sufficiently obtained, and the evaluation of the adhesiveness and the adhesiveness was x (impossible). Comparative Example 2 is an example in which the content of magnesia limestone having a particle size of 1 mm or more is large. The carbon dioxide gas was too much, and the adhesion and the adhesiveness were lowered, and the corrosion resistance was also lowered.
[0031]
　Comparative Example 3 is an example in which the amount of water added is small. The spraying construction was not established and measurement was impossible. Comparative Example 4 is an example in which the amount of water added is large. There were too many open pores and the corrosion resistance decreased.
[0032]
　Comparative Example 5 is an example in which calcined dolomite was used instead of magnesia limestone. Measurement was not possible because the calcined dolomite has strong digestibility. Comparative Example 6 is an example in which limestone is used instead of magnesia limestone. Since limestone (CaCO 3 ) forms a low melting point compound, the corrosion resistance is lowered.
The scope of the claims
[Request 1]
　A hot-type dry spraying material containing a refractory material and a binder, containing
　10% by mass or more and 50% by mass or less of magnesia limestone having a particle size of 1 mm or more in 100% by mass of the refractory material and the binder,
　A dry dry spray material for hot use, which is obtained by adding 10% by mass or more and 50% by mass or less of water to the total amount of the refractory material and the binder of 100% by mass.
[Request 2]
　The hot dry spraying according to claim 1, wherein the content of magnesia limestone having a particle size of less than 1 mm is 25% by mass or less (including 0) in 100% by mass of the total amount of the refractory material and the binder. Material.
[Request 3]
　In the total amount of the refractory material and the binder of 100% by mass, the content of the magnesia limestone having a particle size of 1 mm or more is 20% by mass or more and 40% by mass or less, and
　the addition amount of the water is the refractory material and the The hot dry spray material according to claim 1 or 2, wherein the total amount of the binder is 20% by mass or more and 40% by mass or less with respect to 100% by mass.
[Request 4]
　A composition containing a refractory material and a binder is pressure-fed toward a spray nozzle through a pipe, and a hot dry spraying method in which water is added and hot sprayed at the tip of the spray nozzle, wherein the composition
　is: In a total amount of 100% by mass of the refractory material and the binder, 10% by mass or more and 50% by mass or less of
　magnesia limestone having a particle diameter of 1 mm or more is included, and the addition amount of the water is 100 % by mass of the refractory material and the binder. A hot dry spraying construction method in which 10% by mass or more and 50% by mass or less are applied to the mass%.