JP7088130B2 - A method of kneading a carbon-containing amorphous refractory and a method of manufacturing a molded body of a carbon-containing amorphous refractory using the same. - Google Patents

Description

The present invention relates to a suitable kneading method for a carbon-containing amorphous refractory, and a method for advantageously producing a molded body of a carbon-containing amorphous refractory using this method.

In recent years, the ratio of amorphous refractories to the refractories used in steelworks has increased. The castable refractory, which is one of the amorphous refractories, is often composed only of oxides. The castable refractory requires a process of adding water, kneading, pouring into a mold, drying and firing. Therefore, if hydrophobic carbides or carbon materials are used, the amount of water added to provide fluidity to the extent that it can be easily poured into the mold increases, and the apparent porosity in the dried and fired state increases. This is because it causes an increase and a decrease in corrosion resistance.

On the other hand, in the blast furnace gutter material, it is effective to reduce the wettability with the hot metal and slag because it comes into contact with the hot metal and slag. Therefore, _{Al2O3 -} SiC-C quality castable refractory materials containing hydrophobic carbides and carbon materials and SiC-C quality castable refractories are used. At this time, the carbon raw materials used in the blast furnace gutter material are pitch and carbon black. The pitch has a residual carbon content of 50 to 90% by mass, and traces of the volatile components disappearing due to heating during use remain as pores, which causes an increase in apparent porosity and a decrease in corrosion resistance. Further, carbon black has an extremely small particle size of 20 to 120 nm and has a problem of being easily oxidized. It is considered that these drawbacks can be solved by using graphite such as scaly graphite, which has a high degree of graphitization and is excellent in thermal conductivity and oxidation resistance, which is used in standard bricks.

However, graphite such as scaly graphite has relatively high hydrophobicity among carbon raw materials. Therefore, when graphite is applied to a castable refractory that is constructed using water, the amount of water added to provide sufficient workability (fluidity) increases, and it remains as pores from which water has escaped when it dries after construction. As a result, when graphite is applied to a castable refractory, problems such as an increase in apparent porosity and a decrease in corrosion resistance occur, and it is difficult to use graphite for a castable refractory.

In order to solve the above problems, conventionally, a method has been proposed in which small metal oxide particles such as alumina, which are hydrophilic to scaly graphite, are fixed to the surface of the graphite to improve the hydrophilicity of the scaly graphite. For example, in Patent Document 1, a binder such as phenol resin or tar pitch is diluted with a solvent such as methanol, and fine powder such as alumina is added thereto to prepare a slurry, and the slurry is drip-sprayed and scaly. A technique for adhering fine powder such as alumina to the surface of scaly graphite by coating the surface of graphite is disclosed. Further, Patent Document 2 discloses a technique of fixing small particles such as alumina to the surface of scaly graphite by impact-treating the scaly graphite particles and small particles such as alumina.

Japanese Unexamined Patent Publication No. 11-310474 Japanese Patent No. 3217864

In the technique disclosed in Patent Document 1, in order to impart hydrophilicity to graphite, a fine powder such as alumina is scaly using a phenol resin previously diluted with an organic solvent such as ethanol or a binder such as tar pitch. It is fixed to the surface of graphite. As described above, Patent Document 1 has a problem that pretreatment of graphite is required, which is time-consuming and costly. Further, in the technique disclosed in Patent Document 2, in order to impart hydrophilicity to graphite, 0.2 to 0.6 μm of small particles of alumina or silica are previously dried on the surface of scaly graphite by a high-speed airflow treatment device. It is fixed. Therefore, in this method, in addition to the time and cost required for pretreatment of graphite, there is a problem that dustproof measures are required because fine small particles are used.

An object of the present invention is to propose a method for kneading a carbon-containing amorphous refractory, which does not require pretreatment of a carbon material as in the conventional case and is excellent in pouring work at a low water content, and utilizes this kneading method. The present invention is to propose a method for producing a molded body of a carbon-containing amorphous refractory having excellent durability.

As a result of diligent research to solve the above-mentioned problems of the prior art and to realize the above-mentioned object, the inventors have utilized the novel carbon-containing amorphous fire-resistant kneading method described below and the kneading method thereof. We have come to develop a method for producing a molded body of carbon-containing amorphous fireproof material.

That is, the present invention is a method for kneading a carbon-containing amorphous refractory, first, a refractory raw material containing a carbon material and a hydrophilic substance are mixed and kneaded, then water is added, and then kneading is performed. This is a method for kneading a carbon-containing amorphous refractory, which is characterized by the above.

Further, in the present invention, the carbon-containing amorphous refractory kneaded by the above-mentioned carbon-containing amorphous refractory kneading method is poured into a mold and dried to obtain a molded body of the carbon-containing amorphous refractory. It is a method for producing a molded body of a carbon-containing amorphous refractory, which is characterized by the above.

In the method for kneading a carbon-containing amorphous refractory material according to the present invention, which is configured as described above,
(1) The hydrophilic substance is a hydrophilic coating agent composed of a metal oxide sol such as an alumina sol, a silica sol, a zirconia sol, or a titania sol, or a hydrophilic glass coating agent.
(2) The amount of the hydrophilic substance added is 0.1 to 10 mass% with respect to 100 mass% of the refractory raw material containing the carbon material.
Is considered to be a more preferable solution.

According to the method for kneading a carbon-containing amorphous refractory of the present invention, a carbon-containing amorphous refractory that does not require pretreatment of a carbon material as in the prior art and is inexpensive and easily poured at a low water content and excellent in construction is kneaded. can do. Further, according to the present invention, by using the carbon-containing amorphous refractory kneaded by the above-mentioned carbon-containing amorphous refractory kneading method, it can be constructed with low moisture and the apparent porosity is reduced. It is possible to obtain a molded product of a carbon-containing amorphous refractory exhibiting erosion resistance, which is as good as the refractory of the above.

First, according to the method for kneading a carbon-containing amorphous refractory material according to the present invention, before adding water to the refractory material and kneading, the refractory material containing a hydrophilic substance and a carbon material are mixed and kneaded. By doing so, the entire refractory raw material becomes hydrophilic, so that it becomes possible to knead a carbon-containing amorphous refractory that is excellent in pouring work with a low water content. When the hydrophilic substance adheres to the surface of the carbon material, the carbon material and water become more compatible with each other due to hydrogen bonds with water, etc., so that even a smaller amount of water flows when the refractory material is kneaded with water. It is possible to improve the sex.

As the hydrophilic substance, a coating agent having hydrophilicity can be used. For example, one or more kinds of substances selected from metal oxide sol such as alumina sol, silica sol, zirconia sol, and titania sol can be used. Some of these metal oxide sol have high viscosity, but they can also be used as a solution diluted with water or the like as appropriate.

Various methods can be used for adding the hydrophilic substance to the refractory raw material including the carbon material, but the addition by spraying is preferable because the hydrophilic substance adheres to the entire refractory raw material without bias. ..

As a method for mixing the refractory raw material containing the hydrophilic substance and the carbon material, an appropriate method can be used. The refractory raw material containing the carbon material may be kneaded and mixed before adding the hydrophilic substance, or the refractory raw material containing the carbon material may be kneaded and then mixed. You may.

Here, the empty kneading is kneading without adding water to the refractory raw material containing the carbon material, and is the work of mixing the refractory raw material containing the carbon material to homogenize it. At the construction site, kneading can be performed using a kneading machine such as a pan-type mixer or a biaxial mixer. In the present invention, the effect can be achieved by adding a hydrophilic substance and kneading the refractory material containing a carbon material to the extent that the hydrophilic substance is sufficiently mixed. At a normal construction site, empty kneading may be performed for about 30 seconds to 2 minutes.

In the present invention, if a hydrophilic substance is added to a refractory raw material containing a carbon material and then air-kneaded before water is added to the refractory raw material, what kind of kneading method is used before and after that. You may use it. A method in which a hydrophilic substance is added to a refractory raw material containing a carbon material and then air-kneaded and then kneaded after water is added, or a method in which a refractory material is pre-kneaded and then the hydrophilic substance is added and then air-kneaded. However, any method may be used, such as a method of adding water and then kneading.

The amount of the hydrophilic substance to be added is preferably 0.1 to 10 mass% with respect to 100 mass% of the refractory raw material containing the carbon material. If the amount of the hydrophilic substance to be added is less than 0.1 mass%, the hydrophilic substance is not sufficiently distributed over the entire refractory raw material, so that the entire refractory raw material may not have hydrophilicity. If the amount of the hydrophilic substance to be added exceeds 10 mass%, the refractory raw material may become damp, the viscosity may increase during kneading, and the fluidity may decrease. Therefore, the amount of the hydrophilic substance to be added is preferably 0.1 to 10 mass% with respect to 100 mass% of the refractory raw material containing the carbon material.

In the present invention, a refractory raw material containing a hydrophilic substance and a carbon material is kneaded in an empty manner, and then water is added in an amount necessary to provide fluidity for pouring work to further knead the refractory material. By pouring the kneaded carbon-containing amorphous refractory into a mold and drying it, a molded body of the carbon-containing amorphous refractory can be produced. The carbon-containing amorphous refractory molded body thus obtained can be constructed with low moisture content and the apparent porosity is reduced. It is a molded body of refractory material.

<Example 1>
Examples and comparative examples applied to amorphous refractories containing alumina and SiC are shown in Table 1 below. The refractory raw materials were weighed and various amorphous refractories were prepared by the kneading procedure shown in Table 1. Examples of the hydrophilic substance include Nissan Chemical Industries, Ltd.'s alumina sol AS-200, which is a hydrophilic sol, Nissan Chemical Industries, Ltd.'s Snowtex 20 (registered trademark), which is equivalent to silica sol, and SurLaster, which is a hydrophilic glass coating agent. Zero water (registered trademark) was used.

A table test was performed on the kneaded amorphous refractories of Examples and Comparative Examples using a flow table, and the fluidity of the kneaded material was evaluated. This is defined in JIS R5201 and measures the 15-time tapping flow (hereinafter referred to as tap flow), which is an index of liquidity.

Then, the kneaded amorphous refractories of Examples and Comparative Examples were poured into a 40 × 40 × 160 mm prismatic mold, cured for 24 hours, then unframed, dried at 110 ° C. for 24 hours, and subjected to amorphous refractory. A molded body of the object was obtained. Then, the obtained compact was calcined in a coke breeze at a temperature of 1400 ° C. for 3 hours, and the bending strength at room temperature and the porosity were measured. This bending strength measurement was performed according to the strength test method for castable refractories specified in JIS R 2553. The porosity was measured according to the method for measuring the apparent porosity of refractory bricks specified in JIS R 2205.

Further, regarding the formulation having fluidity, a melting damage test was conducted on the molten slag. The test piece for the melting test was prepared by pouring it into a trapezoidal mold, curing it for 24 hours, removing the frame, drying it at 110 ° C. for 24 hours, holding it in a coke breeze at 1400 ° C. for 3 hours, and cooling it. In the melting test, a crucible was assembled from eight test pieces, a hot metal was charged inside, the temperature was raised to 1550 ° C in a nitrogen stream, and then blast furnace slag was put in every hour and scraped out. Hold for a total of 3 hours, cut vertically (perpendicular to the surface in contact with the hot metal) after cooling, and set the maximum depth of melting loss (intersection between hot metal and slag) as a standard sample (brick for blast furnace pot: alumina-5 mass% SiC). -10 mass% scaly graphite) compared.

The experimental results of Example 1 are shown in Table 1 below. In the evaluation results of Table 1, the amount of added water and the tap flow show the characteristics of the kneaded material of the carbon-containing amorphous refractory kneaded according to the kneading procedure of Table 1, and the apparent porosity, bending strength and melting loss index are shown. , The characteristics of the molded body of the carbon-containing amorphous refractory produced from the kneaded material are shown. Further, in the evaluation results in Table 1, the amount of added water is the total of the amount of water in the hydrophilic substance (hydrophilic agent) and the amount of water added during kneading.

The evaluation results will be described below based on the results in Table 1.
From the results of Comparative Example 1-1, Comparative Example 1-2, and Comparative Example 1-3, when water was added before and during the addition of the hydrophilic substance, the hydrophilic substance was diluted by the added water, and the entire refractory raw material became. It can be seen that high fluidity cannot be obtained because it does not become hydrophilic. Further, from the results of Comparative Example 1-4, if water is added without kneading after the addition, the water is added in a state where the hydrophilic substance does not sufficiently adhere to the refractory raw material. It can be seen that the hydrophilic substance is peeled off and high fluidity cannot be obtained.

On the other hand, in Examples 1-1, 1-2, 1-3 and 1-4, the whole refractory raw material is kneaded after the addition of the hydrophilic substance and water is added. It can be seen that is hydrophilic and exhibits high fluidity.

<Example 2>
Examples and comparative examples applied to amorphous refractories containing alumina and MgO are shown in Table 2 below. The kneading procedure and the evaluation method are the same as in Example 1 applied to the amorphous refractory material containing alumina and SiC.

The evaluation results will be described below based on the results in Table 2.
From the results of Comparative Example 2-1 and Comparative Example 2-2 and Comparative Example 2-3, when the hydrophilic substance is added at the time of water addition and after the water addition, the hydrophilic substance existing on the surface of the carbon material is diluted, and the carbon material is used. It can be seen that high fluidity cannot be obtained because the effect of making the carbon material hydrophilic is diminished because it is difficult to adhere to the surface of the carbon material. Further, from the results of Comparative Example 2-4, if water is added without kneading after the addition, the water is added in a state where the hydrophilic substance does not sufficiently adhere to the refractory raw material. It can be seen that the hydrophilic substance is peeled off and high fluidity cannot be obtained.

On the other hand, in Example 2-1 and Example 2-2, Example 2-3 and Example 2-4, the whole refractory raw material is added because it is kneaded in the air after the addition of the hydrophilic substance and water is added. It can be seen that is hydrophilic and exhibits high fluidity.

The method for kneading a carbon-containing amorphous refractory according to the present invention and the method for producing a molded body of a carbon-containing amorphous refractory using the same are not limited to the above examples, and are various within the scope of the present invention. Can be applied to all kneading of amorphous refractories containing carbon materials.

Claims (3)

A method for kneading an alumina-SiC-graphite-based or alumina-magnesia-graphite-based carbon-containing amorphous refractory, first, one type selected from a refractory raw material containing a carbon material and an alumina sol, a silica sol, a zirconia sol, and a titania sol. Carbon, which is characterized in that it is mixed with a hydrophilic coating agent made of the above metal oxide sol or a hydrophilic substance made of a hydrophilic glass coating agent, kneaded in the air, water is added, and then kneaded. A method for kneading non-standard refractories. The kneading of the carbon-containing amorphous refractory according to claim 1 , wherein the amount of the hydrophilic substance added is 0.1 to 10 mass% with respect to 100 mass% of the refractory raw material containing the carbon material. Method. The carbon-containing amorphous refractory kneaded by the method for kneading the carbon-containing amorphous refractory according to claim 1 or 2 is poured into a mold and dried to obtain a molded body of the carbon-containing amorphous refractory. A method for manufacturing a molded body of a carbon-containing amorphous refractory.