JP2009029041A - Method of producing refractory, and refractory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing refractory by which the refractory having excellent physical property such as strength is produced in a short period of time by easily heating a formed material up to the inside for a short period of time in a state where the effect of oxygen is eliminated. <P>SOLUTION: A refractory composition prepared by containing refractory aggregate and a binder is formed. The formed material is set in a heating container and heated by blowing steam in the container. The steam has high latent heat and the latent heat is transferred to the formed body when the steam is brought into contact with the surface of the formed body to drastically raise the temperature of the surface of the formed body and then, the inside of the formed material is rapidly heated to produce the refractory with excellent productivity in a short period of time. By blowing the steam into the container, air in the container is discharged by the steam to form an atmosphere where oxygen is not present and to carry out a heat treatment in such a state where the effect of oxygen is eliminated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes linings of molten metal containers such as blast furnaces, kneading cars, converters, ladles, smelting reduction furnaces, nozzles provided in continuous casting equipment, immersion nozzles, long nozzles, sliding nozzles, stoppers, etc. The present invention relates to a refractory suitable for use in a melting furnace for non-ferrous metals and a method for producing the refractory.

  Generally, the refractory used in the above application is manufactured as follows. First, a refractory composition is prepared by blending a binder with a refractory aggregate and kneading the mixture with a kneader. Next, this refractory composition is press-molded to obtain a molded product shaped with an uncured binder. After that, by heating the molded product, the binder in the molded product is dried and solidified, the binder is cured, or the binder is changed from curing to carbonization. Can be manufactured (see, for example, Patent Document 1).

Here, when the molded product is heat-treated as described above, and the binder is dried, cured, or carbonized to produce a refractory, the heating method is as follows. Put in a drier and heat it in batch mode for a long time, put the molded product in a shuttle furnace etc. and heat it in batch mode, pass the molded product through a tunnel type heating furnace in continuous mode There are methods such as heating, and the binder is dried and solidified, cured, or carbonized according to the degree of the ambient temperature.
JP 2003-89571 A

  When the molded product is heat-treated as described above, there is no particular problem if the heating atmosphere temperature is a low temperature range of 150 ° C. or lower. However, when the heat treatment is performed in a higher temperature atmosphere, viscosity is increased by the oxygen in the atmosphere. There is a problem that the binder is oxidized and thermally decomposed, and the strength of the refractory is greatly deteriorated.

  Therefore, by covering the periphery of the refractory with coke grains and coke powder and performing the heat treatment in this state, the oxygen is consumed by the coke so that the heat treatment is performed in a state where oxygen in the air does not directly act on the refractory. I have to. However, since this method cannot completely eliminate the influence of oxygen, problems such as corner chipping in the refractory and structural deterioration of the surface of the refractory occur. For example, when a phenol resin is used as a binder, such a phenomenon tends to appear at a heating temperature of 250 ° C. or higher.

  Moreover, the atmosphere which heats a molded object is filled with inert gas, such as argon and nitrogen gas, and the influence by oxygen is interrupted | blocked. In this case, a certain effect can be obtained. However, since a large amount of inert gas is consumed, there is a great problem in terms of cost, which is not practical.

  In any of the above heat treatment methods, a gas such as air is heated, and this heat is transmitted to the surface of the molded product by convection and radiation so that the heat is conducted inside the molded product. Since a gas such as air has a small heat capacity, the heat transfer rate from the gas to the surface of the molded product is small, and the surface temperature of the molded product increases slowly. For this reason, it takes a long time to heat the inside of the molded product, and there is a problem that it takes a long time to produce a refractory. In addition, it takes a long time to heat the interior of the molded product, and as a result, the binder near the surface of the molded product hardens to form a film through which gas does not easily pass. The components are contained inside and the gas pressure becomes high, and there is a risk that the explosion will eventually occur and the molded product may be destroyed or the surface may be cracked.

  Moreover, in order to make preparation of a refractory composition easy or to improve sclerosis | hardenability, a solvent and a hardening | curing agent may be mix | blended. In this case, the solvent is volatilized in the atmosphere during the heat treatment, and the curing agent, for example, hexamethylenetetramine used for the novolac type phenol resin, is thermally decomposed into formaldehyde and ammonia, and most of the ammonia. Will be released into the atmosphere. Furthermore, also in the process of carbonizing the binder, pyrolytic components generated in large quantities are released to the atmosphere. And if these volatiles are released, not only will the work environment worsen, it will also pollute the atmosphere, which will have a negative impact on the environment, and there is a risk of flammable explosions due to volatiles. is there.

  The present invention has been made in view of the above points, and can easily heat a molded product to the inside in a short time, and eliminates the influence of oxygen without using coke or an inert gas. An object of the present invention is to provide a method for producing a refractory which can be heated and can produce a refractory excellent in physical properties such as strength in a short time and can also prevent the release of volatiles. It is what.

  The method for producing a refractory according to the present invention comprises forming a refractory composition prepared by containing a refractory aggregate and a binder, setting the molded product in a heat treatment container, and steaming in the container. And the binder is treated by a process selected from drying, curing, and carbonization.

  Since water vapor has a high latent heat, when the water vapor contacts the surface of the molded product, this latent heat is transmitted to the molded product, and the temperature of the surface of the molded product is rapidly increased to heat the interior of the molded product quickly. The binder can be dried, cured and carbonized in a short time to produce a refractory with high productivity. Moreover, by blowing water vapor into the container, it becomes possible to expel the air in the container with water vapor to create an atmosphere in which oxygen does not exist, and the binder is oxidatively decomposed by eliminating the influence of oxygen. While preventing this, the binder can be dried, cured, and carbonized to obtain a refractory having excellent physical properties such as strength. Further, the volatile matter generated during the heat treatment is taken into the water vapor, and the volatile matter can be prevented from being released to the atmosphere.

  The present invention is characterized in that superheated steam is used as the steam.

  Superheated steam can raise the temperature to about 900 ° C., and can be easily carbonized in addition to heating the binder at a high temperature to dry and cure the binder.

  Further, the present invention is characterized by using a thermosetting binder as the binder of the refractory composition, blowing steam at a temperature equal to or higher than the temperature at which the binder is cured, and curing the binder. It is what.

  According to this invention, a refractory with a hardened binder can be obtained.

  In addition, the present invention is characterized by blowing steam at a temperature equal to or higher than the temperature at which the binder of the refractory composition is carbonized to carbonize the binder.

  According to the present invention, a refractory having a carbonized binder can be obtained.

  In the present invention, the oxygen concentration of the atmosphere in the heat treatment container is 3% or less by volume percentage ratio when the binder is dried, cured, or carbonized by blowing water vapor into the heat treatment container. It is characterized by.

  According to the present invention, it is possible to heat the binder while eliminating the influence of oxygen, and to obtain a refractory having excellent physical properties such as strength.

  Moreover, the refractory according to the present invention is manufactured by any one of the methods described above and has excellent physical properties such as strength.

  According to the present invention, when steam is blown into a heat treatment container in which a molded product is set and the binder is dried, cured, or carbonized, the steam has a high latent heat. This latent heat is transferred to the molded product when water vapor comes into contact with it, and the surface temperature of the molded product is rapidly increased, so that the interior of the molded product can be heated quickly, and the binder is dried in a short time. It can be cured and carbonized to produce a refractory with good productivity. Moreover, by blowing water vapor into the container, it becomes possible to expel the air in the container with water vapor to create an atmosphere in which oxygen does not exist, and the binder is oxidatively decomposed by eliminating the influence of oxygen. While preventing this, the binder can be dried, cured, and carbonized to obtain a refractory having excellent physical properties such as strength. Further, the volatile matter generated during the heat treatment is taken into the water vapor, and the volatile matter can be prevented from being released to the atmosphere.

  Hereinafter, the best mode for carrying out the present invention will be described.

In the present invention, as the refractory aggregate, any material can be used without any particular limitation. For example, electrofused products such as fused alumina and fused magnesia, fired products such as fired magnesia, bauxite, In addition to natural raw materials such as andalusite and sillimanite, any refractory raw material from coarse to fine powders such as calcined alumina and silica powder can be used in combination. Moreover, in order to improve corrosion resistance, it is preferable to mix | blend the powder of the carbonaceous material with bad wettability with molten slag as a fireproof aggregate. As the carbonaceous material, any carbonaceous material such as natural graphite, artificial graphite, coke, carbon black, quiche graphite, mesophase carbon, and charcoal can be used, but it is preferable to use a material having as high purity as possible. As the refractory aggregate, Al, Mg, Ca, Si, or one or more of these alloys can be blended and used. Further, various carbides, borides, nitrides such as SiC, B ₄ C, BN, Si ₃ N _{4 and the} like can be used as an antioxidant for the carbon material.

  A refractory composition can be obtained by blending a binder with these refractory aggregates, and further blending and kneading other components such as a coupling agent as necessary. As the binder, a thermoplastic resin, a thermosetting resin, or the like can be used, but as the thermosetting resin, any of a phenol resin, a furan resin, an epoxy resin, a melamine resin, and the like can be used. These may be used singly or in combination of two or more, and tar / pitch may be used in combination. Among these, it is preferable to use a thermosetting phenol resin as the binder.

  Here, what was prepared by making phenols and aldehydes react in presence of a reaction catalyst can be used for a phenol resin. Phenols mean phenol and derivatives of phenol. For example, in addition to phenol, trifunctional compounds such as m-cresol, resorcinol and 3,5-xylenol, and tetrafunctional compounds such as bisphenol A and dihydroxydiphenylmethane. Bifunctional o- or p such as o-cresol, p-cresol, p-ter-butylphenol, p-phenylphenol, p-cumylphenol, p-nonylphenol, 2,4 or 2,6-xylenol -Substituted phenols can be mentioned, and also halogenated phenols substituted with chlorine or bromine can be used. Of course, in addition to selecting and using one of these, a plurality of types can be mixed and used.

  As the aldehyde, formalin in the form of an aqueous solution is optimal, but forms such as paraformaldehyde, acetaldehyde, benzaldehyde, trioxane, and tetraoxane can also be used. It can be used by replacing with aldehyde or furfuryl alcohol.

  The blending ratio of the above phenols and aldehydes is preferably set so that the molar ratio is in the range of 1: 0.5 to 1: 3.5. As a reaction catalyst, when preparing a novolac-type phenol resin, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, organic acids such as oxalic acid, paratoluenesulfonic acid, benzenesulfonic acid and xylenesulfonic acid, and acetic acid Zinc or the like can be used. When preparing a resol-type phenolic resin, an alkaline earth metal oxide or hydroxide can be used, and an aliphatic group such as dimethylamine, triethylamine, butylamine, dibutylamine, tributylamine, diethylenetriamine, or dicyandiamide. Primary, secondary, tertiary amine, aliphatic amines having aromatic rings such as N, N-dimethylbenzylamine, aromatic amines such as aniline and 1,5-naphthalenediamine, ammonia, hexamethylenetetramine, etc. Other divalent metal naphthenic acids and divalent metal hydroxides can also be used.

  The novolac-type phenol resin and the resol-type phenol resin may be used singly or may be used by mixing both in an arbitrary ratio. Various modified phenolic resins such as silicon modified, rubber modified, boron modified, etc. can be used. However, it does not matter whether the storage stability is stable or the refractory aggregate is acidic (for example, silica) or basic (for example, MgO). Considering the points that can be used, novolak type phenol resin is most preferable. As a curing agent for the novolac type phenol resin, a resol type phenol resin, an epoxy resin, an isocyanate compound, hexamethylenetetramine, trioxane, tetraoxane or the like can be used. Moreover, the curing agent of the resol type phenolic resin can be cured by heating to 100 ° C. or higher, but a curing agent can also be used. As the curing agent, novolac type phenolic resin, epoxy resin, isocyanate compound, organic Esters, alkylene carbonates, and the like can be used. In addition, as a curing catalyst for resol-type phenolic resins, inorganic acids such as hydrochloric acid and sulfuric acid, inorganic compounds such as aluminum chloride and zinc chloride, and organic acids such as benzenesulfonic acid, phenolsulfonic acid, and xylenesulfonic acid should be used. Can do.

  And a refractory composition can be prepared by mix | blending and kneading a binder etc. with a refractory aggregate. The kneading can be performed using any kneading apparatus such as a Simpson mill, Melanger, Eirich, Speed Maller, or Whirlmix. The blending amount of the binder with respect to the refractory aggregate is not particularly limited, but the binder such as phenol resin is in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the refractory aggregate. It is preferable to set.

  Next, by molding the refractory composition prepared as described above, a molded product shaped using an uncured binder as a binder can be obtained. Molding can be performed using an arbitrary press device such as an oil press, a friction press, a vacuum press, or an isostatic press.

  A refractory can be obtained by heat-treating a molded product prepared by molding a refractory composition as described above and drying, curing, or carbonizing the binder in the molded product. In the present invention, water vapor is used as the heating means.

  That is, the molded product can be heated with the heat of water vapor by placing the molded product in a heat treatment container and setting it, and blowing steam into the heat treatment container. Here, the water vapor may be obtained by heating and boiling water, and the vapor pressure is not particularly limited. In addition, the heat treatment container is provided with a blow-in port for introducing water vapor into the heat-treatment container and an exhaust port through which air or excess water vapor in the heat-treatment container is discharged, and the portions other than the blow port and the exhaust port are sealed. What was made to use is used.

  And when water vapor is blown into the heat treatment container in this way, the water vapor is condensed by the contact of the water vapor with the surface of the molded product, and the latent heat is taken away by the molded product, but the water vapor has high latent heat. The temperature of the surface of the molded product rises rapidly. The condensed condensed water is evaporated by the sensible heat of the water vapor, and the temperature of the molded product is further increased by this sensible heat of the water vapor. Here, when the molded product is heated with a gas such as heated air, since the heat capacity of the gas is small, it takes time to raise the surface temperature of the molded product, but when heated with water vapor, the water vapor has Since the molded product can be heated with a large latent heat, the surface temperature of the molded product can be increased in a short time. When the surface temperature of the molded product rises rapidly in this way, heat transfer to the inside of the molded product is also performed quickly, and the entire molded product can be heated at a uniform temperature in a short time.

  Therefore, with a short heat treatment, the binder in the molded product can be dried and solidified, the binder can be cured, or the binder can be cured to carbonized, and fireproof. Products can be manufactured with high productivity. At this time, the binder can be cured by using a thermosetting resin as the binder and a temperature higher than the curing temperature of the thermosetting resin as the steam, and the thermosetting as the steam. By using a resin having a temperature higher than the carbonization temperature of the resin, the binder can be carbonized. In addition, since the entire molded product can be heated to a uniform temperature in a short time, the curing of the binder near the surface of the molded product proceeds faster than the binder inside the molded product. It can prevent cracks and explosions from occurring.

  Here, when heat treatment is performed using high-temperature steam, the temperature rise of the molded product may be abrupt, and blistering may occur in the obtained refractory. At this time, after the heat treatment of the molded product using low-temperature steam, the heat treatment is then performed on the molded product using high-temperature steam, such a blister or the like is generated by performing the heat treatment in two stages. Can be prevented. Of course, the molded product may be heat-treated not only in two stages but also in a plurality of stages in which the temperature of the water vapor is increased in each stage, such as three stages or four stages. Further, as the first stage, after the heat treatment at about 150 ° C. or less, which is hardly affected by oxidation, is performed by a conventional arbitrary method, the second and subsequent stages may be performed by the heat treatment with steam according to the present invention.

  In addition, when the steam is blown into the heat treatment container in which the molded product is set as described above and water is heated, the air containing oxygen in the heat treatment container is pushed out from the exhaust port and eliminated. Is. Since only a few ppm of oxygen is present in the water vapor generated from water, the atmosphere in the heat treatment container becomes almost oxygen-free when the water vapor is blown in and the air is eliminated. Therefore, it is possible to prevent the binder from thermally decomposing under the influence of oxygen when the binder in the molding is heated, dried, cured and carbonized, and the physical properties such as the strength of the molding. Can be prevented, and it is possible to prevent the corners of the refractory from being chipped and the surface of the refractory from being deteriorated. At this time, it is desirable that the oxygen concentration of the atmosphere in the heat treatment container is 3% or less by volume percentage ratio. When the oxygen concentration is 3% or less by volume percentage, the binder can be heat-treated while substantially preventing the binder from thermally decomposing. It is easy to keep the oxygen concentration at 3% or less by volume percentage by blowing water vapor and discharging the air in the heat treatment container.

  In addition, when the molded product is heat-treated as described above, even if volatile gas or decomposition gas is generated from the binder or the like, this gas component is absorbed by the condensed water of the steam whose temperature has decreased, and the odor of the gas is generated. It can be prevented from being released into the working atmosphere. Therefore, it is possible to prevent the working environment from being deteriorated by these gases, to prevent adverse effects on the environment such as air pollution, and further, there is no risk of flammable explosion due to gas. Is. These volatile gases and cracked gases can be drained in a state where the toxicity of the gas is confined in the condensed water. In particular, the volume of water vapor is significantly reduced by condensation, so it is generated by heat treatment. Compared to the case where the volatile gas or the decomposition gas is discharged as it is, it can be discharged in a very small volume by being absorbed in the condensed water, and the processing becomes easy.

  Here, superheated steam can be used as the steam. Superheated steam is water vapor in a complete gas state that is further heated to saturated boiling water to a temperature equal to or higher than the boiling point, and is dry steam at 100 ° C. or higher. The superheated steam can raise the temperature up to about 900 ° C., so that the binder can be heat-treated at a high temperature and the binder can be easily carbonized. When the refractory obtained by such heat treatment is to be treated at a higher temperature, the refractory may be heat-treated in a heating furnace as in the conventional method.

  The time required for heat-treating the molded product with water vapor varies depending on the type of binder and the temperature of water vapor. For example, phenol resin is used as the binder, and heat treatment is performed using water vapor and heated air at the same temperature. Comparing the cases, when water vapor is used, the time can be shortened to about 1/2 to 1/10 of the heated air. The effect of shortening the time becomes higher as the volume of the molded product increases.

  Next, the present invention will be specifically described with reference to examples.

Example 1
A reaction vessel was charged with 940 parts by weight of phenol, 649 parts by weight of formalin 649 parts by weight, and 4.7 parts by weight of oxalic acid, refluxed for about 60 minutes, and allowed to react for 120 minutes. Then, after dewatering at a constant pressure to an internal temperature of 160 ° C., depressurization was performed at 133 hPa to obtain a novolac phenol resin having a softening point of 99 ° C. This novolac type phenol resin was pulverized to a particle size of 106 μm or less by a hammer mill to obtain a powder.

  Next, 70 parts by mass of fused alumina and 30 parts by mass of natural graphite having a purity of 98% were used as the refractory aggregate, and these were put into a mixer, and 7.2 parts by mass of the above-mentioned novolac type phenol resin powder, hexa 0.8 parts by mass of methylenetetramine was added, 2.5 parts by mass of methanol was further added, and kneaded for 10 minutes to obtain a wet refractory composition.

  Next, 250 g of this refractory composition was put into a mold having an inner diameter of 45 mm and molded at a pressure of 98 MPa using a hydraulic press to obtain a molded product.

  In addition, as the heat treatment container, a superheated steam small batch tester (“Model GE-10B” manufactured by Nomura Engineering Co., Ltd.) having effective dimensions in the warehouse of width 390 mm, depth 370 mm, and height 390 mm was used. This heat treatment container has a blow-in port for introducing water vapor at the bottom and an exhaust port at the ceiling, which can be sealed by closing the door at the front opening.

  Then, the above molded product was set on a Teflon (registered trademark) sheet in a heat treatment container. At this time, as the molded product, a hole in which a temperature sensor is inserted by opening a hole from the center of the side surface to the inner center of the molded product and a molded product without such a hole are used. (The same applies to the following Examples and Comparative Example 1).

  After setting the molded product in the heat treatment container in this manner, the superheated steam at 450 ° C. is supplied and blown from the blowing port, and the supply flow rate of superheated steam is set to about 300 ° C. so that the temperature in the container is maintained at 300 ° C. While controlling at 200 L / min, blowing of superheated steam was continued.

  Thus, when the temperature rise of the central part of the molded product was measured with a temperature sensor while blowing superheated steam, it reached 200 ° C in 9 minutes from the start of blowing superheated steam, 250 ° C in 16 minutes, and 300 ° C in 32 minutes. . Moreover, when the oxygen concentration in the container was measured with a gas concentration detector ("testo 325-2" manufactured by Test Co., Ltd.), the measurement limit was 0.2 vol% or less (volume percentage ratio) immediately after the start of superheated steam blowing. there were.

  Then, after the temperature of the molded product reached 300 ° C., a refractory material in which the phenolic resin of the molded product was cured was obtained by performing the heat treatment by continuously blowing superheated steam for 3 hours.

The refractory material obtained in this way was measured in a case where no hole was drilled. The bulk specific gravity measured in accordance with JIS R2001 was 2.511, and the volatile content (%) = 100−. (Mass after heat treatment (g) / mass before heat treatment (g)) × 100
The volatile content at the time of heat treatment at 300 ° C. determined from the above formula was 0.25% by mass, and the compressive strength measured according to JIS R2206 was 24.5 MPa. Moreover, when the surface of the refractory was observed, a slight amount of blistering was observed. Furthermore, the odor coming out from the exhaust port during the heat treatment as described above was extremely weak.

(Example 2)
The same molded product and heat treatment container as in Example 1 were used.

  First, as a first stage, superheated steam at 300 ° C. is supplied and blown in, and the superheated steam supply flow rate is controlled to about 150 L / min so that the temperature in the container is maintained at 200 ° C. Insufflation continued. Thus, when the temperature rise of the center part of the molding was measured while blowing superheated steam, it reached 150 ° C. in 13 minutes and 200 ° C. in 28 minutes from the start of blowing superheated steam. After the temperature of the molded product reached 200 ° C., this superheated steam was continuously blown for 60 minutes for heat treatment.

  Subsequently, as a second stage, 450 ° C. superheated steam is supplied and blown, and the superheated steam supply flow rate is controlled to about 200 L / min so that the temperature in the container is maintained at 300 ° C. Insufflation continued. Thus, when the temperature rise of the center part of the molded product was measured while blowing superheated steam, the temperature reached 250 ° C. in 5 minutes and 300 ° C. in 15 minutes from the start of blowing of 450 ° C. superheated steam. After the temperature of the molded product reached 300 ° C., this superheated steam was continuously blown for 2 hours for heat treatment.

  When the refractories obtained by the heat treatment were measured, the bulk specific gravity was 2.520, the volatile content was 0.23% by mass, and the compressive strength was 25.0 MPa. Also, when the surface of the refractory was observed, no blisters were seen and it was clean.

(Example 3)
In Example 2, the heat treatment was performed by continuously blowing superheated steam in the second stage for 24 hours. Other than that, a refractory was obtained in the same manner as in Example 2.

  The bulk specific gravity of this refractory was 2.518, the volatile content was 0.30% by mass, and the compressive strength was 24.3 MPa. When the surface of the refractory was observed, the surface was clean with no swelling or whitening.

Example 4
In Example 2, the heat treatment was performed by blowing hot steam at the first stage for 1 hour, and the heat treatment was continued by blowing superheated steam at the second stage for 1 hour. Further, as a third stage, superheated steam at 800 ° C. is supplied and blown in, and superheated steam is blown in while controlling the supply flow rate of superheated steam to about 250 L / min so that the temperature in the container is maintained at 600 ° C. For 3 hours, and heat treatment was performed.

  Thus, the refractory material by which the phenol resin in a refractory material was carbonized was obtained by heat-processing in high temperature in the 3rd step. When the obtained fired refractory was measured, the bulk specific gravity was 2.502, the volatile content was 1.60% by mass, and the compressive strength was 18.1 MPa. Further, when the surface of the fired refractory was observed, no blisters were seen and it was clean.

(Comparative Example 1)
The molded product produced in Example 1 was placed on a Teflon (registered trademark) sheet in a high-temperature dryer (“Model DRD360DA” manufactured by Toyo Seisakusho Co., Ltd .: Dimension width 300 mm, depth 300 mm, height 300 mm). I set it up. The inside temperature was set to 300 ° C. and heat treatment was performed.

  Thus, when the temperature rise of the center part of the molding was measured while heating at 300 ° C., it reached 200 ° C. in 18 minutes, 250 ° C. in 35 minutes, and 300 ° C. in 80 minutes. And after the temperature of the molded article reached 300 ° C., this heating was continued for 3 hours to carry out a heat treatment.

  When the refractory obtained by the heat treatment was measured, the bulk specific gravity was 2.519, the volatile content was 0.34% by mass, and the compressive strength was 23.9 MPa. Also, when the surface of the refractory was observed, no blisters were seen and it was clean. Further, when the heat treatment was performed as described above, the odor coming out from the exhaust port of the high-temperature dryer was extremely strong.

(Comparative Example 2)
In Comparative Example 1, a refractory was obtained in the same manner as in Comparative Example 1, except that heating was continued for 24 hours.

  When the refractory obtained by heat treatment in this manner was measured, the bulk specific gravity was 2.461, the volatile content was 2.68% by mass, and the compressive strength was 19.5 MPa. When the surface of the refractory was observed, no blistering was observed, but a slight whitening phenomenon was observed on the surface.

(Comparative Example 3)
The molded product produced in Example 1 was placed in a heat-resistant box, which was then coated with coke and set in an electric furnace (“Siliconit Electric Furnace Type BSH-1530” manufactured by Siliconit Takao Kogyo Co., Ltd.). Then, the temperature is increased to 600 ° C. at a temperature increase rate of 10 ° C./min. Further, after holding at this temperature for 3 hours, the temperature is decreased to perform heat treatment to obtain a fired refractory in which the phenol resin in the refractory is carbonized. It was.

  When the obtained fired refractory was measured, the bulk specific gravity was 2.490, the volatile content was 1.82% by mass, and the compressive strength was 16.7 MPa. Further, when the surface of the fired refractory was observed, no blisters were seen and it was clean.

  As seen in the comparison between Examples 1 to 3 and Comparative Examples 1 and 2, and as seen in the comparison between Example 4 and Comparative Example 3, the refractory of each Example is the refractory of each Comparative Example. It was confirmed that a refractory having a higher compressive strength and superior strength can be produced.

Claims (6)

  Molding a refractory composition prepared containing a refractory aggregate and a binder, setting the molding in a heat treatment container, blowing steam into the container, drying and curing the binder A method for producing a refractory, characterized by performing a treatment selected from carbonization.   The method for producing a refractory according to claim 1, wherein superheated steam is used as the steam.   A thermosetting binder is used as the binder of the refractory composition, and water vapor at a temperature equal to or higher than a temperature at which the binder is cured is blown to cure the binder. 2. A method for producing a refractory according to 1.   The method for producing a refractory according to claim 1 or 2, wherein the binder is carbonized by blowing steam at a temperature equal to or higher than a temperature at which the binder of the refractory composition is carbonized.   The oxygen concentration of the atmosphere in the heat treatment container when the water vapor is blown into the heat treatment container to perform the treatment selected from drying, curing, and carbonization of the binder is 3% or less by volume percentage ratio. Item 5. A method for producing a refractory according to any one of Items 1 to 4.   A refractory produced by the method according to claim 1.