JPH08285471A - Laying construction of prepared unshaped refractory - Google Patents

Abstract

PURPOSE: To carry out a constant construction every time without influence of changes in environmental conditions and shorten the time period of drying process without a burst by a method wherein mixture of refractory material and binder is filled in a place and steam is injected to obtain a set refractory. CONSTITUTION: A mixture of refractory material and binder is filled in place and steam is injected to obtain a set refractory, thus unshaped refractory work is carried out. Thereby, refractory work from pouring step to curing and drying steps can be carried out within a remarkable short period of time without troubles such as a burst, resulting in an improvement of efficient use of molten metal vessels. This method is applicable also to material containing carbonic raw material such as graphite, and a prepared unshaped refractory material having a considerably-improved spalling resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing an indefinite refractory material which is simple to construct and can significantly reduce curing and drying times.

[0002]

2. Description of the Related Art In recent years, the proportion of amorphous refractories used as refractories for various molten metal containers has increased, and castable refractories that are easy to construct have come into widespread use, especially due to the recent shortage of manpower. ing. Castable refractories mainly consist of a refractory material and a binder, and the one using alumina cement as the binder is the most common.

The conditions such as the pot life and hardening time required for the castable refractory during kneading differ depending on the construction, and these are greatly affected by the temperature conditions. Adjustments are being made by increasing or decreasing and adding a curing accelerator, a curing retarder, and the like.

Further, in order to efficiently operate the equipment, it is required that the molten metal container lined with the lining is put into a state in which it can be operated as soon as possible, so that the curing and drying processes should be completed in the shortest possible time. desirable. However, in recent castable refractories, in order to obtain a dense construction body,
A method of kneading with ultra-fine powder material with low water content has been generalized, and there is a problem that if the temperature rising rate is increased in order to shorten the drying process, the risk of the construction body exploding increases. Therefore, addition of organic fibers (JP-A-59-190276) or aluminum lactate (JP-A-62-100483) is disclosed as a method for preventing explosion. Further, in Japanese Patent Laid-Open No. 4-136687, in castable refractory, a part or all of the added water is replaced with a volatile non-aqueous solvent to volatilize the solvent, or the construction body is ignited to burn the solvent. There is disclosed a method of shortening the curing and drying time by carrying out.

[0005]

There are many types of curing accelerators and curing retarders for the purpose of adjusting the pot life and the curing time during kneading in castable refractories, depending on the type of curing binder. The effects are not quantitative in any of them, and it is difficult to deal with changes in conditions on the day of construction, and work problems such as insufficient pot life and poor curability have not been completely resolved.

Addition of organic fibers, aluminum lactate, etc. increases the explosion resistance of the castable refractory, so that the temperature rising rate during drying can be increased, and as a result, the drying process can be shortened, but alumina cement Since the material used as a binder has the drawback that the risk of explosion increases when the curing temperature is low, it is necessary to increase the addition amount of them in order to obtain the desired effect in the winter, and for that purpose There was a drawback that the strength was reduced. Therefore, in order to maintain the strength of the construction body, it is inevitable to add a small amount of anti-explosive agent and to adopt a gentle dry heating pattern until the moisture inside the material is completely removed. The effect of shortening the drying process by adding the inhibitor was not sufficient.

A method of substituting a part or all of the added water during kneading with a volatile non-aqueous solvent such as methyl alcohol or xylene to shorten the curing and drying time is that the solvent is flammable and there is a risk of fire. However, some solvents have deficiencies such as toxic volatiles and adverse effects on the human body.

An object of the present invention is to provide a method for constructing an indefinite refractory material which can be constantly applied without being affected by changes in environmental conditions, and which can be used immediately without drying due to shortened drying process. To provide.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted various studies on a method for constructing an irregular-shaped refractory and, as a result, injecting steam into a mixture of a refractory material and a binder filled in a construction site. The present invention has been completed by succeeding in obtaining a cured product in which the curing and drying processes can be performed in a very short time and in which explosion does not occur, by a simple method omitting the kneading process on site. That is, the present invention is a method for constructing an indefinite refractory material, which comprises filling a mixture of a refractory material and a binder in a construction site and injecting steam to obtain a cured product.

As the refractory material used in the present invention, known acidic, neutral, basic or natural or artificial materials can be used alone or in combination of two or more depending on the purpose of use. The particle size composition may be freely set according to the purpose of use, but since the filling degree of the mixture of the refractory material and the binder affects the physical properties of the cured product, the particle size composition is such that the mixture is more easily packed more densely. Is desirable. It is also a preferable method to improve the filling property of the mixture by a mechanical method before injecting steam. For example, after the mixture is put into the construction site, it is crushed with a stick, a vibration motor is installed in the mold to fill it with vibration, the form is made movable by hydraulic pressure, etc., and the mixture is pressurized to improve the filling property. A method of raising it is possible. Other,
The packing property can be improved by effectively using the spherical clinker. As the spherical clinker, alumina-like ones are commercially available, and those having various particle sizes are available.

In the present invention, the fluidity of the material is not required, as compared with the conventional construction of castable refractory materials, because there is no step of kneading and pouring. Therefore, although it is effective in improving spalling resistance and preventing slag penetration, it is difficult to use an amount of various carbon-based raw materials that are sufficient to obtain a sufficient effect because the fluidity is impaired. Similar treatment is possible. As the carbon-based raw material, scaly graphite, earth-like graphite, pitch, coke, mesophase carbon, electrode scrap and the like can be used alone or in combination of two or more depending on the purpose. When using a carbon-based raw material, it is preferable to use an appropriate amount of silicon carbide, glass powder, metal powder or the like in combination to prevent carbon oxidation. In addition, when a thermosetting substance such as phenol resin is mixed in the refractory material, it shows a curing reaction due to the heat of water vapor and strengthens the structure of the matrix, so it is an effective method for improving the strength of the construction body. is there.

The binder used in the present invention may be a hydraulic binder used in ordinary water-based castable refractories. For example, alumina cement, slaked lime, phosphate,
Examples thereof include silicates, aluminum salts, activated alumina, activated magnesia and the like. They can be used alone or in combination of two or more, but according to the study by the present inventors, a binder structure mainly composed of alumina cement was most advantageous for obtaining a high-strength construction product. The addition amount of the binder is preferably in the range of 0.1 to 30 wt% with respect to 100 wt% of the refractory material. If the addition amount is less than 0.1 wt%, sufficient curability cannot be obtained, and if it exceeds 30 wt%, the fire resistance of the construction product is deteriorated. Therefore, a more preferable range is 1 to 20 wt%. In order to allow the hardening reaction to proceed uniformly within the construction body, it is necessary to sufficiently mix the refractory material and the binder so that the binder is well dispersed.

Unlike the conventional castable construction, the construction method according to the present invention does not affect the workability due to environmental conditions, and therefore it is not necessary to adjust the construction conditions such as the type and amount of the binder involved in the workability. Therefore, it is possible to select an optimal binder composition in terms of material characteristics without considering workability. In addition to these, it is preferable to use various additives such as sintering aids and fibers used for ordinary castable refractories depending on the purpose.

The steam, which is a feature of the construction method according to the present invention, is supplied from a device such as a boiler, adjusted to an appropriate pressure by a pressure regulator, and injected into the refractory material. It is assumed that the steam injection holes are formed in the mold at appropriate intervals and are connected to the pipe from the steam supply device. It is desirable that the piping connected to the injection hole be of a type that can be easily attached and detached. Further, it is desirable to install a breathable sheet or the like in the injection hole to prevent the refractory material from flowing out into the pipe. The pressure at the time of injection is not particularly limited, and may be determined by the balance with the diameter of the injection hole, but it is preferable that the pressure is such that it smoothly enters the filled refractory material, and if the pressure is too low, the fire resistance If it is not sufficiently filled in the material and is too high on the contrary, the refractory material is blown away to form voids, which is not preferable. The pipe for injecting the water vapor may be made by using a standard commercial product having a diameter of 1 to 1.5 inches and a hose, and in this case, according to the study of the present inventors, 0.3 to 1.2 kg / cm ² The pressure was appropriate.

The temperature of the injected steam does not have to be changed depending on the kind of the refractory material and the binder used, but the effect of heating the refractory material, the mold, the permanent brick, etc. to accelerate the curing reaction and the ease of handling. Considering that, 100 to 20
A temperature of 0 ° C is considered to be the proper range. Further, when a thermosetting substance is added to improve the strength of the construction body, steam at a temperature higher than the temperature at which the substance shows a curing reaction is required.

The construction method according to the present invention is applied to a molten metal container such as a blast furnace trough, a hot metal ladle, a mixed pig wheel car, a converter, a ladle, RH, DH, and a tundish. However, it can be applied to both the initial material and the repair material of those containers.

[0017]

Operation When a mixture of a refractory material and a binder is filled in a construction site provided by a mold and water vapor is injected, the binder reacts with water and the curing proceeds. This hardening reaction is markedly promoted by heating the refractory material, the mold, the permanent bricks, etc. by the heat of the steam, as in the hardening reaction when the usual water-based castable is kneaded with hot water. The higher the temperature of the water vapor, the greater this effect is.If the mixture is filled sufficiently tightly in advance, the phenomenon that curing progresses during the construction and the prescribed filling cannot be obtained during the construction as seen in the normal mixing of hot water with pouring material. Does not happen.

Water vapor can be uniformly supplied to the entire mixture by injecting it from a plurality of injection holes provided in the mold according to the area where the irregularly shaped material is applied. The injected steam comes into contact with the hydraulic binder and takes in as much water as necessary for the curing reaction, and the excess steam not involved in the reaction heats the refractory material, the mold, and the permanent bricks. It is released outside the construction body while exerting its effect. The time for injecting steam varies depending on the amount of material to be applied, the number of injection holes, the pressure of steam, etc., but it is desirable to stop the injection when the surface of the refractory material releases excess steam and the surface becomes wet. This is to reduce the amount of water vapor adhering to the refractory material and reduce the amount of water remaining in the construction body as much as possible. The surplus steam passes through while the hardening reaction of the refractory material is progressing, and after being released, fine pores are left in the construction body. The fine pores serve as passages through which water escapes when the construction body is dried.

The castable refractory containing alumina cement as a binder has a Ca content due to a hydration reaction when the curing temperature is low.
A large amount of O.Al ₂ O ₃ .10H ₂ O is produced and its dehydration temperature is 1
Since it overlaps with the dehydration temperature range of free water of 10 ° C. or higher, the vapor pressure in the material tends to increase and the explosion phenomenon tends to occur. However, in the construction method according to the present invention, the refractory material, the mold, etc. are heated. , When using alumina cement as a binder, the mineral produced by hydration is 3CaO ・ Al ₂ O ₃・ 6H ₂ O
And Al ₂ O ₃ .3H ₂ O are the main constituents. Since the dehydration temperature of crystal water of these minerals is as high as 230 ° C. or higher, the dehydration reaction occurs at a different time from the dehydration of free water when the temperature of drying is increased. Therefore, it is possible to avoid the steam pressure in the construction body from becoming excessively high, so that the risk of explosion is extremely small.

Due to the effects that the water content remaining in the construction body is small, the fine pores are left, and the increase of the water vapor pressure in the construction body is suppressed, the explosion of the explosion is prevented even if the temperature is rapidly raised during the drying. Since the risk is extremely low, the drying process can be completed in a significantly shorter time than the conventional castable refractory. This effect is exhibited not only when using alumina cement but also when using other binders.

Further, in the present invention, since the time required for curing, curing and drying is significantly shortened, the effect of cracking, tissue destruction, etc. due to slaking can be reduced for materials using basic raw materials such as magnesia. There is also.

[0022]

The present invention will be specifically described with reference to the following examples.
Table 1 shows the compounding ratio in the alumina-spinel material and each test result. Example is 100mm diameter, 100mm height
Then, make a 1-inch diameter injection hole on the bottom surface, and fill a well-mixed mixture into a cylindrical mold with a breathable sheet attached to the hole, and add steam for 30 minutes at a pressure of 0.5 kg / cm ^2. A sample was prepared by injecting for 2 seconds and curing. Examples 4 and 5 employ a method of improving the filling property of the composition before steam injection. In Comparative Example 1, a mold having the same shape was used, a predetermined amount of water was added, and a sample was prepared by ordinary pouring construction. The explosion test was carried out for 3 hours in Examples and for 24 hours in Comparative Examples, and the samples were placed in an electric furnace maintained at 800 ° C. and observed for the presence or absence of explosion. The embodiment of the present invention has a very short deframeable time and a good explosion resistance. Embodiment 10 of the present invention
The physical properties after heat treatment at 00 ° C. for 5 hours are inferior to those of the comparative example, but if the filling of the composition is improved before injecting steam as in Examples 4 and 5, it is possible to obtain physical properties at a level close to that of the comparative example. .

Table 2 shows the blending ratio in the alumina-silicon carbide-carbonaceous material and each test result. The method for preparing the sample was the same as in Example 5 in Table 1 by pouring water vapor after compacting with a rod during compounding and filling. In Comparative Example 2, a mold having the same shape was used and molded by ordinary pouring construction. The physical properties are 1 in an electric furnace with a reducing atmosphere.
It was measured after heat treatment at 000 ° C. for 5 hours. In the oxidation test, after heat treatment at 1000 ° C. for 5 hours in an electric furnace, the thickness of the decarburized layer on the cut surface was measured, and the value obtained by dividing the measured value of Comparative Example 2 by the measured value of each sample is shown as an oxidation resistance index. It was In the spalling test, each sample was placed in an electric furnace maintained at 1400 ° C, and after 10 minutes, the sample was taken out and forcedly cooled to room temperature. This operation was repeated 3 times, and the elastic modulus before and after thermal shock was measured (elasticity after thermal shock was measured. Modulus) / (elastic modulus before thermal shock) was evaluated as the elastic modulus maintenance ratio, and the value of Comparative Example 2 was 100.
It was shown by the index. In the examples of the present invention, the deframeable time was extremely short, and the oxidation resistance and the spalling resistance were both equal to or higher than those of the comparative examples, and those using graphite showed particularly excellent results.

The composition and construction method of Example 5 was applied to A Steel Works 3
Example 11 The results of applying the 00T ladle to the general wall lining
As shown in Table 3. The results of Comparative Example 3 in which the composition of Comparative Example 1 is normally poured into a ladle of the same type for construction are also shown. In Example 11, cores each having a steam injection hole with a diameter of 1.5 inches were installed in a ladle at a ratio of 1 per 1 m square, and then the material was sufficiently packed to a predetermined height while being tamped with a rod, Steam was injected from each injection hole connected by a pipe from the steam supply device. The pressure of water vapor at this time is 0.8 kg / cm ² ,
The temperature was 180 ° C. and the injection was carried out for 15 minutes. The steam injection time in Table 3 also includes the time required for desorption of the pipe, and still the construction was completed in a shorter time than the comparative example. In addition to the time required to cure the amorphous material, the curing time also includes the time required to construct the furnace material in the slag line part of the ladle and the floor part. In Example 11, the time from construction to the end of drying was shortened to about one-third as compared with Comparative Example 3, and although the durability was almost the same, there was a merit of improving the efficiency of ladle operation.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

INDUSTRIAL APPLICABILITY As described above, in the method for constructing an irregular-shaped refractory according to the present invention, by injecting water vapor to cure the refractory material, the steps from construction to curing and drying are performed as compared with the conventional castable refractory. However, it is possible to solve problems such as working troubles and explosions, and it is possible to greatly improve the operation efficiency of the molten metal container.
Further, the present construction method can be applied to a material containing a carbon-based raw material such as graphite, and can provide an amorphous material with significantly improved spalling resistance.

Claims (1)

[Claims] 1. A method for constructing an indefinite refractory material, which comprises filling a mixture of a refractory material and a binder into a construction site and injecting steam to obtain a cured product.