JP7003849B2 - Manufacturing method of castable refractory - Google Patents

Description

The present invention relates to a method for producing a castable refractory, particularly a method for producing a castable refractory used as a lining furnace material for a steelmaking kiln facility.

At the furnace construction site, the castable refractory is kneaded with water using a mixer, and the obtained kneaded material is simply poured into the furnace while applying vibration to the furnace site. Can be built. Therefore, the castable refractory is positioned as a very important refractory in order to improve the efficiency of the furnace construction work and save labor.

In the construction work of the lining furnace material of the iron-making kiln furnace equipment using castable refractories, it is indispensable to produce a precise construction body. Therefore, a fine refractory raw material having a maximum particle size of 5 μm or less is used for the castable refractory. Its action is to disperse the refractory raw materials with a maximum particle size of 5 μm or less during the kneading process until they exist independently as individual particles, and fill the gaps between the aggregate particles that make up the castable refractory. It is said that it contributes to the production of a precise construction body.

However, since a fine refractory raw material having a maximum particle size of 5 μm or less has a large specific surface area and therefore has a large adhesive force and surface energy, the maximum particle size is easily 5 μm or less during the kneading process. As a result of the refractory raw materials coalescing and aggregating, there was a problem that they could not be dispersed separately until they existed independently as individual particles, and a dense work piece could not be produced.

Several proposals have been made to solve these problems. For example, in Patent Document 1, only a refractory raw material having an average particle size of 10 μm or less, which is difficult to disperse in a castable refractory during the kneading process, is taken out, and the refractory raw material is mixed with a dispersant and water in advance to prepare a mixed aqueous solution. Then, using this mixed aqueous solution, a castable refractory containing no refractory raw material having an average particle size of 10 μm or less is kneaded, and then a castable refractory is cast and molded. There is.

In Patent Document 2, in a method of kneading a castable refractory containing a refractory raw material having an average particle size of 10 μm or less and a dispersant to produce an amorphous refractory kneaded product, at least one of the refractory raw materials having an average particle size of 10 μm or less. It is characterized by adding a portion and a dispersant to water, using an emulsifying disperser to obtain a mixed aqueous solution in which the content of the refractory raw material is specified, and then kneading the mixed aqueous solution and the balance of the castable refractory. A method for producing a kneaded product of a castable refractory is disclosed.

Patent Document 3 proposes an amorphous refractory for pots using a predetermined amount of amorphous silica fine particles in a method for producing an amorphous refractory for pots. Further, in Patent Document 3, it is stated that amorphous silica fine particles having the smallest particle size among the constituent raw materials of the refractory may be used in the form of silica sol instead of the form of dry powder. It has been disclosed.

Japanese Unexamined Patent Publication No. 8-239276 Japanese Unexamined Patent Publication No. 2012-82117 Japanese Unexamined Patent Publication No. 5-185202

However, even if the methods described in Patent Documents 1 and 2 are used, the problem that a precise construction body cannot be produced has not been solved. As a result of diligent investigation of the cause, the present inventor has used an emulsifying disperser to prepare a mixed aqueous solution of at least a part of a refractory raw material having an average particle size of 10 μm or less, a dispersant, and water. It was found that the silica with the smallest particle size was not dispersed but aggregated. That is, in the prior art, silica having the smallest particle diameter and a maximum particle diameter of less than 1 μm is not dispersed and aggregated in the manufacturing process of the kneaded material of the castable refractory, so that a dense construction body cannot be produced. Became clear. If a precise construction body cannot be created, the corrosion resistance is lowered and the strength of the construction body is lowered, resulting in inferior durability.

Further, in Patent Document 3, during kneading with a mixer, the silica sol rapidly gels with magnesia, which is a constituent material of an amorphous refractory for a pot, and hardens. There was a problem that it was not possible to pour in while applying vibration to the location.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to be able to produce a precise work piece and to manufacture a castable refractory material having excellent workability and durability. , To provide a new and improved method for manufacturing castable refractories.

As a result of diligent research, the present inventor has made that a silica sol that is alkaline and has an average particle size of 50 nm or more coexists with a refractory raw material that is alkaline when in contact with water, such as magnesia and alumina cement. It was found that it showed a phenomenon of non-condensation.

From the above, the present inventor uses a silica sol that is alkaline and has an average particle size of 50 nm or more, and is a fire-resistant raw material having a maximum particle size of 5 μm or less in the silica sol aqueous solution in which a dispersant is dissolved. After preparing a slurry in which It led to the invention.

The gist of the present invention is as follows.
(1) A method for producing a castable refractory containing a refractory raw material excluding a silica raw material, silica sol and alumina cement.
A step of dissolving a dispersant in an alkaline silica sol aqueous solution containing silica having an average particle size of 50 nm or more, and
Further, a step of dispersing a refractory raw material having a maximum particle size of 5 μm or less in the silica sol aqueous solution to obtain a slurry, and a step of obtaining a slurry.
A method for producing a castable refractory, which comprises a step of kneading a mixture obtained by mixing the slurry, alumina cement, a dispersant, and a refractory raw material having a minimum particle size of more than 5 μm. ..
(2) The total mass content of the refractory raw material having a maximum particle size of 5 μm or less and the silica derived from the silica sol aqueous solution in the slurry is 30% by mass or more and 70% by mass or less (1). The method for manufacturing a castable refractory according to 1).
(3) The method for producing a castable refractory according to (1) or (2), wherein the silica sol aqueous solution has a pH of 8.0 or more and 13.0 or less at 25 ° C.
(4) The method for producing a castable refractory according to any one of (1) to (3), wherein the average particle size of the silica in the silica sol aqueous solution is 50 nm or more and 500 nm or less.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to manufacture a precise construction body using a castable refractory material, and as a result, the life of the iron-making kiln equipment can be extended, and as a result, productivity is improved. Further, the above-mentioned method according to the present invention can be cast and is excellent in workability.

Hereinafter, preferred embodiments of the present invention will be described in detail. The method for producing a castable refractory according to the present embodiment is a method for producing a castable refractory containing a fire-resistant raw material excluding silica raw material, silica sol and alumina cement.
A step of dissolving the dispersant in an alkaline silica sol aqueous solution containing silica having an average particle size of 50 nm or more (first step), and
Further, a step of dispersing a refractory raw material having a maximum particle size of 5 μm or less in an aqueous solution of silica sol to obtain a slurry (second step), and a step of obtaining a slurry.
It has a step (third step) of kneading a mixture obtained by mixing a slurry, an alumina cement, a dispersant, and a refractory raw material having a minimum particle size of more than 5 μm. Hereinafter, each step will be described in detail.

(First step)
First, in the first step, the dispersant is dissolved in an alkaline silica sol aqueous solution containing silica having an average particle size of 50 nm or more.

As described above, in the present embodiment, the silica sol aqueous solution is used as the silica raw material. The reasons for using silica sol are as follows. This is because in the silica sol aqueous solution produced by chemical synthesis, amorphous silica particles having a maximum particle diameter of less than 1 μm that aggregates in dry mixing exist in a stably dispersed state in the aqueous solution.

The average particle size of silica (particles) in such an aqueous solution of silica sol is, for example, 50 nm or more and 500 nm or less, preferably 50 nm or more and 300 nm or less. When the average particle size of silica is within the above range, the structure of the castable refractory can be sufficiently dense and the durability can be improved. In the present specification, the "particle size" means the particle size measured by the laser diffraction / scattering method, and the "average particle size" means the volume-based average particle size measured by the laser diffraction / scattering method. (D50, median diameter).
As the content of silica in the silica sol aqueous solution, for example, 20 to 40% by mass can be used.

Further, in the present embodiment, the silica sol aqueous solution is alkaline. Refractory raw materials such as magnesia and alumina cement become alkaline when in contact with water. Conventionally, rapid gelation has been observed when such a refractory raw material and silica sol are mixed. However, in the present embodiment, since the silica sol aqueous solution is alkaline in advance, there is no significant change in liquid property even when mixed with a refractory raw material such as magnesia or alumina cement, and silica in the slurry. Aggregation and condensation are prevented. As a result, silica can be uniformly dispersed even when mixed with a refractory raw material, and a dense castable refractory can be produced. Further, since silica is uniformly dispersed in the mixture, the fluidity of the mixture becomes appropriate and the workability is excellent.

The pH of the silica sol aqueous solution may be in the range of alkalinity, and is, for example, 8.0 or more and 13.0 or less, preferably 8.0 or more and 11.0 or less at 25 ° C. When the pH of the silica sol aqueous solution is within the above range, silica can be more reliably and uniformly dispersed in the mixture even when the silica sol aqueous solution and the refractory raw material are mixed.

In this step, the dispersant is dissolved in the silica sol aqueous solution as described above. The reason for dissolving the dispersant in the silica sol aqueous solution is to disperse the refractory raw material having a maximum particle diameter of 5 μm or less when the silica sol and the refractory raw material having a maximum particle diameter of 5 μm or less are mixed. When a dispersant and a refractory raw material having a maximum particle size of 5 μm or less are simultaneously added to the silica sol aqueous solution and mixed, the dispersant is dissolved in the silica sol aqueous solution, and the dissolved dispersant is adsorbed on the surface of the refractory raw material. This is because the refractory raw materials having a maximum particle size of 5 μm or less collide with each other and aggregate before exerting the action of dispersing the refractory raw materials.

The dispersant is not particularly limited as long as it can disperse a fire-resistant raw material described later, and examples thereof include alkali metal phosphates, polycarboxylates, polyacrylic acid salts, alkyl sulfonates, aromatic sulfonates and the like. It can be used, and one or more of these can be used. The concentration of the dispersant is preferably in the range of 0.1 to 0.6% by mass with respect to 100% by mass of the silica sol aqueous solution. As the dispersant, either powder or liquid can be used.

(Second step)
In this step, a fire-resistant raw material having a maximum particle size of 5 μm or less is dispersed in a silica sol aqueous solution in which a dispersant is dissolved to obtain a slurry. The reason why the refractory raw material having a maximum particle size of 5 μm or less contained in the castable refractory is dispersed in the silica sol aqueous solution in which the dispersant is dissolved in advance is as follows. Refractory raw materials with a maximum particle size of 5 μm or less have strong adhesive force due to their large specific surface area. Therefore, from the beginning, the refractory includes alumina cement, a dispersant, and a maximum particle size of 5 μm or less. This is because in the method of adding water to all the raw materials and kneading them, the refractory raw materials having a maximum particle size of 5 μm or less remain agglomerated. Therefore, prior to mixing with alumina cement or the like, a refractory raw material having a maximum particle size of 5 μm or less is dispersed in this step.

Here, the refractory raw material having a maximum particle diameter of 5 μm or less does not contain silica (silica raw material). This prevents the newly added silica from aggregating and losing the denseness of the structure of the castable refractory. On the other hand, in the present embodiment, silica derived from the above-mentioned silica sol is used as a substitute for the silica component in the refractory raw material.

As the refractory raw material other than silica having a maximum particle size of 5 μm or less, those generally used as refractory raw materials can be used. The types include, for example, alumina, magnesia, titania, zirconia, _itria , spinel, zircon, mullite, cordierite, SiC, Si 3N ₄ , AlN, B ₄ C, BN, ZrB ₂ , and carbon. It can be exemplified.

Further, in the obtained slurry, the total mass content (solid content) of the refractory raw material having a maximum particle size of 5 μm or less and the silica derived from the silica sol aqueous solution is preferably 30% by mass or more and 70% by mass or less. In a slurry in which a refractory raw material other than silica having a maximum particle size of 5 μm or less is dispersed in a silica sol aqueous solution in which a dispersant is dissolved, the mass of the refractory raw material other than silica having a maximum particle size of 5 μm or less and the silica component in the silica sol. The reason why the mass content of the reduced mass is 30% by mass or more and 70% by mass or less is that a construction body having a dense structure can be produced. When the mass content in the slurry is less than 30% by mass, the amount of the refractory raw material having a maximum particle diameter of 5 μm or less that fills the gaps between the aggregate particles constituting the castable refractory is small depending on the composition of the refractory raw material. In addition, it may not be possible to manufacture a construction body having a fine structure. If the mass content in the slurry is more than 70% by mass, the amount of the refractory raw material having a maximum particle size of 5 μm or less existing in the slurry is too large depending on the composition of the refractory raw material, so that each refractory raw material is present. As a result of the adjacent distances becoming too close, it may not be possible to produce a construction body having a fine structure because it aggregates due to the action of van der Waals attraction.
The total mass content of the refractory raw material having a maximum particle size of 5 μm or less and the silica derived from the silica sol aqueous solution is preferably 40% by mass or more and 70% by mass or less.

When dispersing a fire-resistant raw material other than silica having a maximum particle size of 5 μm or less in a silica sol aqueous solution in which a dispersant is dissolved, in addition to manual stirring, a rotary stirrer for rotating a stirrer, a container rotates or vibrates. -A device that shakes, a device that stirs with bubbles, or the like may be used, or a device that can collide the silica sol aqueous solution discharged from the nozzle and stir with the collision energy may be used.

(Third step)
Next, in this step, a mixture obtained by mixing a slurry, alumina cement, a dispersant, and a refractory raw material having a minimum particle size of more than 5 μm is kneaded. This makes it possible to manufacture a castable refractory.

In order to produce a construction body having a fine structure, the amount of the slurry (the amount of the entire slurry) to be added externally to the refractory raw material having a minimum particle size of more than 5 μm is preferably 7 to 20% by mass.

In this step, as the alumina cement, for example _, an alumina cement containing CaO / _Al2O3 can be used.
The blending ratio of the alumina cement is preferably in the range of 2 to 6% by mass with respect to 100% by mass of the refractory raw material having a minimum particle size of more than 5 μm. If the compounding ratio of the alumina cement is less than 2% by mass, the compounding ratio is small, so that the strength may be inferior, and if it exceeds 6% by mass, the corrosion resistance may be inferior.

The dispersant used in this step is not particularly limited, and alkali metal phosphates, polycarboxylates, polyacrylic acid salts, alkyl sulfonates, aromatic sulfonates and the like can be used. One kind or two or more kinds can be used. Further, the dispersant used in this step may be the same as or different from the dispersant used in the first step. The concentration of the dispersant is preferably in the range of 0.1 to 0.6% by mass with respect to 100% by mass of the refractory raw material having a minimum particle size of more than 5 μm. As the dispersant, either powder or liquid can be used.

Further, as the refractory raw material having a minimum particle diameter of more than 5 μm, a material generally used as a refractory raw material can be used. Examples of the type include those consisting of alumina, magnesia, _spinel , zircon, mullite, cordierite, chamotte, SiC, and B4C. Even in a refractory raw material having a minimum particle diameter of more than 5 μm, silica (silica raw material) is not contained in order to avoid aggregation.

The maximum particle size of the refractory raw material having a minimum particle size of more than 5 μm may be the same as that used for a general castable refractory material, but is preferably 30 mm or less. If the maximum particle size is more than 30 mm, the fineness of the structure of the construction body may decrease even if a silica sol aqueous solution in which a refractory raw material other than silica having a maximum particle size of 5 μm or less is dispersed in advance. be.

Further, materials other than those described above may be added to and mixed with the slurry. Examples of such a material include an explosion inhibitor. As the anti-explosion agent, generally used ones may be used. For example, vinylon fiber, aluminum lactate, metallic aluminum as a foaming agent, azodicarbonamide and the like can be mentioned.
The compounding ratio of the anti-explosion agent may be a general prescription. For example, it is desirable that the outer diameter is in the range of 0.01 to 0.03% by mass with respect to 100% by mass of the refractory raw material having a minimum particle size of more than 5 μm.

A slurry in which a refractory raw material other than silica having a maximum particle size of 5 μm or less is dispersed in an alkaline silica sol aqueous solution in which a dispersant is dissolved, an alumina cement, and a refractory raw material having a minimum particle size of more than 5 μm containing a dispersant. In addition, any of a vortex mixer, a turbo mixer, a twin-screw mixer, and a high-speed mixer can be used as the mixer used for kneading.

The castable refractory obtained as described above uses silica sol, and since silica is uniformly dispersed, it is possible to form a dense structural structure. Therefore, the construction body manufactured by the obtained castable refractory material is excellent in its physical strength. Further, since the construction body manufactured by the obtained castable refractory has a fine structural structure, it is also excellent in corrosion resistance. Therefore, the construction body manufactured by the castable refractory has excellent durability.

Further, the castable refractory has an appropriate fluidity due to the uniform dispersion of each material, and is excellent in workability.

The castable refractory obtained by the above manufacturing method can be used for any purpose as long as it is used as a refractory. In particular, the castable refractory obtained by the above manufacturing method is suitable for the lining furnace material of the iron-making kiln furnace equipment, which requires a precise construction body.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

<1. Manufacture of castable refractories>
(Comparative Examples 1 to 5)
As the castable refractory material according to Comparative Examples 1 to 4, a typical refractory material used as a lining furnace material for the iron-making kiln furnace equipment was selected. Comparative Example 1 and Comparative Example 2 are blast furnace Ohi lining furnace materials, Comparative Example 3 is a molten steel pot lining furnace material, and Comparative Example 4 is a tundish lining furnace material. In addition, Comparative Example 5 is an example in which the castable refractory shown in Comparative Example 3 was manufactured by the method disclosed in JP-A-8-239276.

In Comparative Examples 1 to 4, water was added to a castable refractory in which alumina cement and a dispersant were mixed externally with respect to 100% by mass of a refractory raw material having a maximum particle size of 30 mm or less, and kneaded using a vortex mixer. This is an example of manufacturing.

A laser diffraction type particle size distribution measuring device (SALD-3100, manufactured by Shimadzu Corporation) was used to measure the particle size of the silica sol. The particle size was calculated on a volume basis.

(Examples 1 to 4)
Example 1 is Comparative Example 1, Example 2 is Comparative Example 2, Example 3 is Comparative Example 3, and Example 4 is a method for producing a castable refractory according to the present invention based on the raw material composition of Comparative Example 4. Is an example of applying. In Examples 1 to 4, the silica sol in which the dispersant was dissolved and the refractory raw material other than silica having a maximum particle size of 5 μm or less were mixed using a ball mill. A slurry was prepared by loading a silica sol in which a dispersant was dissolved and a refractory raw material other than silica having a maximum particle size of 5 μm or less into a ball mill device and mixing them for 3 hours. The obtained slurry was mixed and kneaded with the refractory raw material shown in Table 1 and the dispersant to obtain a castable refractory as a kneaded product. As the silica sol, Na ⁺ stable alkaline sol (pH: 10.0) was used in the product name Snowtex manufactured by Nissan Chemical Industries, Ltd.

(Example 5)
A castable refractory was produced in the same manner as in Example 4 except that the blending ratio of each material was changed as shown in Table 1.
(Example 6)
A castable refractory was produced in the same manner as in Example 1 except that the blending ratio of each material was changed as shown in Table 1.

(Comparative Example 6)
A castable refractory was produced in the same manner as in Example 2 except that Na ⁺ stable alkaline sol (particle diameter: 10 to 15 nm, pH: 10) was used in the product name Snowtex manufactured by Nissan Chemical Industries, Ltd. as the silica sol. did.
(Comparative Example 7)
A castable refractory was produced in the same manner as in Example 3 except that an acidic sol (particle size: 50 to 80 nm, pH: 4.0) in the product name Snowtex manufactured by Nissan Chemical Industries, Ltd. was used as the silica sol.

<2. Evaluation>
The kneaded product was evaluated by measuring free flow and tap flow, measuring apparent porosity and bending strength after drying at 110 ° C. for 24 hours, and measuring corrosion resistance.

The free flow and tap flow of the kneaded product were measured according to the flow test procedure specified in JIS-R 2521. When the fire-resistant raw material having a maximum particle size of 5 μm or less is sufficiently dispersed in the kneading process of the castable refractory, the measured values of the free flow and tap flow of the obtained kneaded material are improved, so that the dispersibility of the kneaded material is evaluated. Adopted as.

The apparent porosity and bending strength after drying at 110 ° C. for 24 hours were measured as follows. The kneaded product was cast and molded while applying vibration to a frame having a shape of 65 mm × 65 mm × 230 mm. Then, after curing at room temperature for 24 hours, the frame was removed, and the sample was dried at 110 ° C. for 24 hours to prepare a sample. The apparent porosity was measured according to JIS-R 2205: 1992. The bending strength was measured with a span of 100 mm using a sample having a cross section of 65 mm × 65 mm and a length of 230 mm in accordance with JIS-R 2213: 1995.

Corrosion resistance was evaluated by the rotary erosion furnace method using blast furnace slag as the erosion material. The corrosion resistance evaluation sample is prepared by pouring a kneaded product into a metal frame of a predetermined size while applying vibration, curing it at room temperature for 24 hours, drying it at 110 ° C. for 24 hours, and firing it in the air at 1000 ° C. for 6 hours. Made. In the rotary erosion furnace method, the evaluation sample is lined in the rotary erosion furnace, and when the surface temperature of the evaluation sample reaches 1600 ° C., slag is put into the furnace and the molten slag is discharged after 30 minutes. The test was conducted by repeating the operation of adding a new slag four times. After the test, the sample was cut and the corrosion resistance was evaluated by measuring the maximum erosion depth on the cut surface. Corrosion resistance is determined with Example 1, Example 2, Example 3, and Example 4 with the maximum erosion depth of the samples of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 as a length of 100%, respectively. Relative evaluation. Further, for Example 5, the maximum erosion depth of the sample of Comparative Example 4, for Example 6, the maximum erosion depth of the sample of Comparative Example 1, and for Comparative Example 5, the maximum erosion depth of the sample of Comparative Example 3 The corrosion resistance was relatively evaluated by setting the maximum erosion depth of the sample of Comparative Example 2 for Comparative Example 6 and the maximum erosion depth of the sample of Comparative Example 3 for Comparative Example 7 to 100%. The smaller the value, the better the corrosion resistance.

Tables 1 and 2 show the raw material formulations of the castable refractory in each Example and each comparative example, and the evaluation results of the obtained castable refractory.

In Examples 1 to 4, the refractory raw materials having a maximum particle size of 5 μm or less were dispersed without agglomeration in the kneading process, and as a result, free flow and tap flow were measured when compared with the measured values of Comparative Examples 1 to 4. It can be seen that the value is improved, the apparent porosity after drying at 110 ° C. for 24 hours is lowered, and a dense work piece can be produced. As an effect, it has been confirmed that the bending strength after drying at 110 ° C. for 24 hours and the corrosion resistance are improved.

In Example 5, since the mass content in the slurry is less than 30% by mass, the compactness is lowered, and the apparent porosity after drying at 110 ° C. for 24 hours is increased as compared with Example 4. You can see that. Therefore, a decrease in bending strength and a slight decrease in corrosion resistance after drying at 110 ° C. for 24 hours are observed.

In Example 6, since the mass content in the sol is more than 70% by mass, the refractory raw materials having a maximum particle size of 5 μm or less are aggregated, and the measured values of free flow and tap flow are compared with those of Example 1. And the apparent porosity increased after drying at 110 ° C. for 24 hours, resulting in a decrease in fineness. Therefore, a decrease in bending strength and a slight decrease in corrosion resistance after drying at 110 ° C. for 24 hours are observed.
It should be noted that Examples 5 and 6 had characteristics that did not cause any problem in practical use.

In Comparative Example 5, since the slurry was prepared by adding a refractory raw material having a maximum particle size of 5 μm or less and a dispersant to water and mixing them, silica having the smallest particle size did not disperse and aggregated. Compared with Example 3, it can be seen that the measured values of free flow and tap flow decreased, and the apparent porosity increased after drying at 110 ° C. for 24 hours, and a precise work piece could not be produced. Therefore, a decrease in bending strength and a decrease in corrosion resistance after drying at 110 ° C. for 24 hours are observed.

In Comparative Example 6, although the silica sol used was alkaline, the average particle size of the silica was less than 50 nm, and the silica sol was condensed during the kneading process. Therefore, the measured values of free flow and tap flow were compared with those of Example 2. It can be seen that a precise construction body could not be produced due to a decrease in the apparent porosity and an increase in the apparent porosity after drying at 110 ° C. for 24 hours. Therefore, a decrease in bending strength and a decrease in corrosion resistance after drying at 110 ° C. for 24 hours are observed.

In Comparative Example 7, since the silica sol was acidic, the silica sol was condensed during the kneading process. Therefore, as compared with Example 3, the measured values of free flow and tap flow were lowered, and after drying at 110 ° C. for 24 hours. It can be seen that the apparent porosity has increased and a precise construction body has not been produced. Therefore, a decrease in bending strength and a decrease in corrosion resistance after drying at 110 ° C. for 24 hours are observed.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

According to the present invention, it is possible to eliminate the aggregation of refractory raw materials having a maximum particle size of 5 μm or less in the kneading process of a castable refractory material, thereby having a dense structure and extremely excellent durability, for example, for ironmaking. As a result of being able to manufacture the lining furnace material of the kiln equipment, the life of the construction body, for example, the iron-making kiln equipment can be significantly extended.

Claims (4)

A method for producing a castable refractory containing a refractory raw material excluding silica raw material, silica sol and alumina cement.
A step of dissolving a dispersant in an alkaline silica sol aqueous solution containing silica having an average particle size of 50 nm or more, and
Further, a step of dispersing a refractory raw material having a maximum particle size of 5 μm or less in the silica sol aqueous solution to obtain a slurry, and a step of obtaining a slurry.
A method for producing a castable refractory, which comprises a step of kneading a mixture obtained by mixing the slurry, alumina cement, a dispersant, and a refractory raw material having a minimum particle size of more than 5 μm. .. The first aspect of the slurry is characterized in that the total mass content of the refractory raw material having a maximum particle diameter of 5 μm or less and the silica derived from the silica sol aqueous solution is 30% by mass or more and 70% by mass or less. The method for manufacturing a castable refractory described. The method for producing a castable refractory according to claim 1 or 2, wherein the silica sol aqueous solution has a pH of 8.0 or more and 13.0 or less at 25 ° C. The method for producing a castable refractory product according to any one of claims 1 to 3, wherein the average particle size of the silica in the silica sol aqueous solution is 50 nm or more and 500 nm or less.