JP2002137970A - Water-based castable refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based castable refractory containing carbon excellent in spalling resistance and corrosion resistance. SOLUTION: The water-based castable refractory is characterized in that the water castable refractory consists of carbon black raw material, the ash content of which is 0.5 wt.% or less and pitch raw material, the fixed carbon content of which is 75-95 wt.%, and that the weight ratio of contents of the carbon black raw material and the pitch raw material is 1:0.1-1:0.9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based amorphous refractory and a water-based castable refractory used for lining and repairing various molten metal containers such as hot metal and molten steel.

[0002]

2. Description of the Related Art Amorphous refractories used for lining molten metal containers are required to have excellent corrosion resistance and spalling resistance. Among them, spalling resistance is an important factor that affects the life of a refractory. The cracks generated in the lining of the molten metal container may be gradually generated by repeated heating and cooling during long-term use, or may be relatively large in the early stage of use. The former is considered to be caused by the sintering of the material, and it is possible to improve to some extent by suppressing the sintering, but the latter is caused by the fact that the stress generated by the thermal expansion of the material exceeds the strength of the material And there has been no effective countermeasure.

[0003] Above all, the blast furnace gutter is a structure having a length of 10 m or more that is constrained by a steel shell used as a passage for hot metal and slag flowing from the blast furnace. Because it occurs, spalling is easy to occur. For this reason, alumina, silicon carbide, and carbonaceous amorphous refractories containing extremely low thermal expansion coefficients of silicon carbide and carbon raw materials have become the mainstream of the lining of blast furnace gutters. Materials that have been added (JP-A-4-43981, JP-A-5-70250) and materials to which a large amount of carbon material has been added (JP-A-10-279369) have been proposed. The fact is that sufficient control has not been achieved for

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carbon-containing water-based amorphous refractory having excellent spalling and corrosion resistance, which is used for lining and repairing various molten metal containers. And

[0005]

In order to suppress cracks generated in the lining of a molten metal container in a relatively early stage of use, it is necessary to minimize the thermal expansion of the material or to increase the strength higher than the generated thermal stress. Although it is conceivable to apply the material to the material, the most effective countermeasure is to absorb the thermal stress generated by the material deforming itself, that is, to provide thermal stress absorbability. The present inventors have concluded that the magnitude of the thermal stress absorption can be evaluated by the expansion rate under load, and the expansion rate under load is low from low to high temperatures, and the softening point under load is low and the expansion under load is low. The rate was also oriented to low materials. That is, a material that is easily softened (deformed) by a load (stress) is considered to easily absorb thermal stress, and thus the present invention has been achieved.

As a result of intensive studies, the present inventors have determined that a specific carbon black and pitch are used as carbon raw materials, and that the mixing ratio thereof is limited to provide optimum thermal stress absorption from a low temperature range to a high temperature range. Has become possible. Furthermore, the present inventors have concluded that a material having a high density and excellent durability can be obtained by specifying the added amounts of the carbon black and the pitch, and have reached the present invention.

That is, in order to solve the problem of the present invention, a water-based amorphous refractory is made to contain a carbon black raw material having an ash content of 0.5% by weight or less and a pitch raw material having a fixed carbon amount of 75 to 95% by weight. In addition, by setting the weight ratio of the content of the carbon black raw material to the content of the pitch raw material to 1: 0.1 to 1: 0.9, the thermal stress absorption from a high temperature range to a low temperature range is increased. (Claim 1)

Further, the total content of the carbon black raw material and the pitch raw material is 3 to 1 with respect to 100% by weight of the refractory composition.
By setting the content to 5% by weight, sufficient relaxation of stress can be obtained, and sintering can be sufficiently suppressed from the middle stage to the end stage of use. (Claim 2)

Further, by setting the apparent porosity after drying of the water-based amorphous refractory to 13.0% or less, a material excellent in spalling resistance and corrosion resistance can be obtained. (Claim 3)

Further, the softening temperature of the pitch raw material is set at 200 to 450 ° C.
By setting the particle size to 0.5 mm or less, the material softens at a low temperature of 500 ° C or less, so that thermal stress absorption in a low temperature range can be increased, and explosion resistance when dried at less than 200 ° C And dispersibility can be improved. (Claim 4)

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The carbon black raw material used in the present invention is an ultrafine powder raw material that is difficult to be sintered at a high temperature, and therefore has a role of increasing thermal stress absorption in a high temperature range.
The ash content (iron, aluminum, silicon, etc.) of the carbon black raw material is 0.5% by weight or less, preferably 0.4% by weight or less. If the ash content exceeds 0.5% by weight, the fluidity of the material tends to decrease with the addition, and it is difficult to obtain a dense construction body, and it is not preferable because it is easy to fire in a high temperature range.

The pitch material used in the present invention is 500 ° C.
Since it softens at the following low temperatures, it has a role of increasing thermal stress absorption in a low temperature range. The fixed carbon amount of the raw material that can be used is 75 to 95% by weight. If the amount of fixed carbon is less than 75% by weight, it is not preferable because the amount of volatile components is large and a dense refractory structure cannot be obtained after heating, and those having an amount of fixed carbon exceeding 95% by weight are generally difficult to obtain. Therefore, it is not preferable. The softening temperature and the particle size of the pitch used in the present invention are preferably 200 to 450 ° C., and the particle size is 0.5 mm or less. If the softening temperature is lower than 200 ° C., the explosion resistance during drying may decrease, and if the particle size exceeds 0.5 mm, the dispersibility decreases, which is not preferable.

In the present invention, the content ratio of the carbon black raw material and the pitch raw material needs to be 1: 0.1 to 1: 0.9 by weight, preferably 1: 0.2 to 1: 0.8. This is the ratio at which the thermal stress absorbency of the carbon black in the high temperature range and the thermal stress absorbency of the pitch in the low temperature range are most efficiently achieved. Carbon black raw material 1
If the amount of the pitch raw material is less than 0.1 part by weight relative to the part by weight, the thermal stress absorption of the material in a low temperature range is unfavorably small.

If the pitch raw material exceeds 0.9 parts by weight with respect to 1 part by weight of the carbon black raw material, it is not preferable because the thermal stress absorption of the material in a high temperature range is small and there is no crack suppressing effect. The pitch raw material has the effect of softening at low temperatures and increasing thermal stress absorption, but has the effect of inhibiting thermal stress absorption to form carbon bonds and develop strength at high temperatures. Need to be less than the carbon black raw material.

In the present invention, the total content of the carbon black raw material and the pitch raw material is 3 to 15% by weight based on 100% by weight of the refractory composition. If the amount is less than 3% by weight, the stress relaxation property is not sufficiently imparted, and the sintering is not sufficiently suppressed from the middle stage to the end stage of use. If it exceeds 15% by weight, the viscosity of the material increases and the amount of water for obtaining fluidity increases,
A precise organization cannot be obtained.

The amorphous refractory for blast furnace gutters of the present invention having an apparent porosity of 13.0% or less after drying is extremely excellent in corrosion resistance in addition to spalling resistance. The amorphous refractory of the present invention is a water-based amorphous refractory that can be kneaded with water, and is not a so-called non-aqueous amorphous refractory containing a resin or the like.

The amorphous refractory of the present invention can be used in iron and steel making furnaces, such as hot metal ladles, mixed iron wheels, converters, ladles, RHs, tundishes, and various other industrial furnaces. Particularly suitable for blast furnace main gutter, hot metal gutter, slag, inclined pouring gutter, etc. As the refractory aggregate and the refractory fine powder constituting the amorphous refractory of the present invention, depending on the application, fused alumina, sintered alumina, calcined alumina, bauxite, ban clay shale, kyanite, mullite, rock stone, Silica, electrofused spinel, sintered spinel, electrofused magnesia, sintered magnesia, zircon, zirconia, silicon carbide, silicon iron nitride, silicon, ferrosilicon, aluminum, boron carbide, clay, bentonite, hydrous amorphous silica, anhydrous anhydrous One selected from the group consisting of shaped silica and the like, or one or more of them can be used in combination.

The amorphous refractory of the present invention has an ash content of 0.1%.
Carbon black of 5% by weight or less and carbon material other than pitch having a fixed carbon amount of 75 to 95% by weight, for example, graphite, coke, etc., can be added together. The range is not inhibited.

Further, the amorphous refractory of the present invention may use, as a binder, a cold-setting binder such as alumina cement or clay, or a thermosetting curing agent such as sodium silicate. Further, the amorphous refractory of the present invention may optionally contain a dispersant used in a usual casting material. As the dispersant, for example, alkali metal phosphate, alkali metal carboxylate, alkali metal humate, naphthalene sulfonic acid formalin condensate, sodium polycarboxylate, and the like, and substances capable of obtaining the same effects as these One or two or more can be selected and used.

(Examples) Hereinafter, the water-based amorphous refractory of the present invention will be further described with reference to examples. The following measurements were performed under the following conditions. * A method for measuring the ash content of carbon black. 105 ± 1 in a magnetic crucible pre-baked at 750 ± 25 ° C for 1 hour
After weighing 2.0 g of the sample dried at 1 ° C. for 1 hour, incineration is performed in a muffle furnace at 750 ± 25 ° C., and the remaining amount is indicated as a percentage of the sample. * Pitch carbon: A: 90% fixed carbon, softening point 320 ° C, particle size -45 µm, coal pitch B: 80% fixed carbon, softening point 280 ° C, particle size -0.3mm, coal pitch C: 65% fixed carbon, softening point 120 ° C, grain size -1mm, coal pitch * Sparing resistance: normal shape (230mm x 114mm x 65mm)
Using a sample cast and cast in an electric furnace
1500 ° C-30 minutes ← → 30 minutes of natural cooling were repeated 30 times as one cycle, and the state of crack generation was evaluated in four stages. (◎ Greatly excellent, ○ Excellent, △ Inferior, × Inferior) * Actual machine test: 350mm thick on the lining of the blast furnace main gutter of 18m in length
After about 10,000 tons of iron pouring, and 1
After passing 00000 t of iron, the state of crack generation was evaluated on a three-point scale. (○ excellent, Δ inferior, × greatly inferior) A blank test result indicates that the actual machine test was not performed. * Measurement of expansion rate under load and softening point under load: (JIS R2209) Sample: A cast sample was prepared in a shape of 50 mm x 50 mm and dried at 105 ° C for 24 hours. The relationship between the expansion rate under load and the softening point under load is as shown in FIG.

Table 1 shows the expansion rate under load and the softening point T1 of the material at 500 ° C. and 1500 ° C. and the expansion rate as numerical values indicating the thermal stress absorption of the material. The expansion coefficient under load was measured at a load of 0.2 MPa according to JIS-R2209 (method of measuring softening point under load). The smaller the coefficient of expansion under load at each temperature and the lower the softening point of the load, the greater the thermal stress absorption. (The stress itself can be absorbed by the material itself deforming under the load, that is, the stress. ), As a result, the occurrence of cracks can be suppressed.

As shown in Table 1 of FIG. 2, the water-based amorphous refractory of the present invention (Examples 1 to 8) has a carbon black raw material having an ash content of 0.5% by weight or less and a fixed carbon amount of 75 to 95% by weight. % Pitch material, and the weight ratio of the content of the carbon black material to the pitch material is 1: 0.1 to 1: 0.9, and the total amount of the carbon black material and the pitch material is refractory. 3 to 15% by weight based on the product and the apparent porosity after drying is 13.0% or less. Therefore, the expansion rate under load at 500 ° C and 1500 ° C is 0.4% or less. And the load softening point T1 is 1350 ° C or less, and the expansion rate under load at the load softening point T1 is 0.70%.
The results are as follows, and it can be seen that the thermal stress absorption is very excellent. The water-based amorphous refractory of the present invention has greatly improved spalling resistance, has suppressed cracking in the initial stage of use in an actual machine, and has greatly improved durability.

[0023]

According to the first aspect of the present invention, a water-based amorphous refractory contains a carbon black raw material having an ash content of 0.5% by weight or less and a pitch raw material having a fixed carbon content of 75 to 95% by weight, and When the weight ratio of the content of the carbon black raw material to the content of the pitch raw material is 1: 0.1 to 1: 0.9, the thermal stress absorption is excellent, and the spalling resistance particularly in the early stage of use can be greatly improved.

In the invention according to claim 2, the total content of the carbon black raw material and the pitch raw material is set to 3 to 15% by weight with respect to 100% by weight of the refractory composition, so that an appropriate mixing ratio can be obtained. Therefore, the sintering from the middle stage to the end stage of use is sufficiently suppressed, and the generation of cracks in heating and cooling can be suppressed.

According to the third aspect of the present invention, by setting the apparent porosity of the water-based amorphous refractory after drying to 13.0% or less, the refractory having excellent spalling resistance and corrosion resistance can be obtained.

Further, in the invention according to claim 4, the softening temperature of the pitch raw material is in the range of 200 to 450 ° C., and the particle size is 0.5 m
m or less, it softens at a low temperature of 500 ° C or less, so that thermal stress absorption in a low temperature range can be increased and 200 ° C
Explosion resistance and dispersibility at the time of drying at less than the above can be improved.

As described above, the water-based amorphous refractory of the present invention is excellent in thermal stress absorption as compared with the refractory of the comparative example, and the spalling resistance particularly in the early stage of use is greatly improved. Therefore, when applied to the lining of a molten metal container, the advantage of the carbon raw material is maximized, and a lining with extremely excellent spalling resistance is obtained. In addition, by increasing the total amount of the carbon raw material based on the proper mixing ratio, sintering from the middle stage to the end stage of use can be sufficiently suppressed, and the generation of cracks can be suppressed even in heating and cooling. Furthermore, by keeping the apparent porosity after drying at a certain value or less, the amorphous refractory for blast furnace gutters of the present invention has a strong resistance to molten metal and slag. In addition, the water-based amorphous refractory of the present invention is not only for pouring,
It is also applicable to wet spraying using a pump.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an expansion rate under load and a softening point under load.

FIG. 2 is a table comparing Examples 1 to 8 of the present invention with Comparative Examples 1 to 5;

[Explanation of symbols]

 T1 is the softening point under load. X The coefficient of expansion under load at 500 ° C. Y The expansion rate under load at 1500 ° C. Z The expansion rate under load at the softening load point T1.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoyuki Komatsubara 4-7-1, Kudankita, Chiyoda-ku, Tokyo Inside Kawashiro Brick Co., Ltd. (72) Inventor Takehichi Suzuki Kudankita, Chiyoda-ku, Tokyo 42-chome 1-7 item Kawashira Brick Co., Ltd. F term (reference) 4G033 AA02 AA03 AA09 AB25 BA01 4K015 EC08 4K051 AA01 AB03 BE03

Claims (4)

[Claims] 1. A refractory composition containing a carbon black raw material having an ash content of 0.5% by weight or less and a pitch raw material having a fixed carbon amount of 75 to 95% by weight, wherein the carbon black raw material and the pitch raw material The weight ratio of content is 1: 0.1
A water-based amorphous refractory, characterized in that the ratio is 1: 0.9. 2. The water-based amorphous refractory according to claim 1, wherein the total content of the carbon black raw material and the pitch raw material is 3 to 15% by weight based on 100% by weight of the refractory composition. . 3. The water-based amorphous refractory according to claim 1, wherein the apparent porosity after drying is 13.0% or less. 4. The blast furnace gutter water system according to claim 1, wherein the pitch raw material has a softening temperature of 200 to 450 ° C. and a particle size of 0.5 mm or less. Fixed refractories.