JPH09315872A - Wet spraying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for spraying a castable refractory material, that takes advantage of simpleness of a conventional spraying method while securing good service durability of the applied castable refractory materiel, which is almost equivalent to that obtained by a conventional casting method.

SOLUTION: In this method, 0.01 to 1.0wt.% of a dispersant is added to 100wt.% of a refractory composition on the outer percentage basis to form a low cement castable refractory material, wherein the refractory composition consists of 67 to 97.5wt.% of refractory aggregate having ≤10mm grain size, 2 to 25wt.% of a refractory superfine powder having ≤10μm particle size and 0.5 to 8wt.% alumina cement. The resulting castable refractory material is mixed with water by using a mixer to form a castingworkable mix. Thereafter, the mix is transferred to a spray nozzle with a pressure-transfer pump, and then, sprayed from the nozzle while adding an alkali silicate solution as a shape retention property providing agent together with compressed air to the mix at a point in the spray nozzle in a 0.1 to 1.5wt.% ratio to 100wt.% of the powdery low cement castable refractory material on the outer percentage basis. At this time, the alkali silicate solution used has an SiO₂/R₂O molar ratio of 2.0 to 3.3 (R₂O is an alkali metal oxide) and specific gravity expressed in terms of Be (Baume degree) at 15°C of ≥40.

COPYRIGHT: (C)1997,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for wet spraying a low-cement castable used as a lining material for a molten metal container such as a ladle and a tundish and a blast furnace tapping gutter.

[0002]

2. Description of the Related Art In recent years, as the durability of a casting material has been improved, the lining material of a molten metal container has shifted from a brick to a casting material by a casting method which is easy to perform. However, in terms of labor saving, the pouring work still has the complication of the framing work. In this respect, spraying does not require a formwork and allows for quick and local repairs, which contributes to further labor savings and enables flexible support for repair plans. Therefore, the spraying method tends to increase, in which case,
The mainstream was dry spraying. However, the dry spraying method has problems in that the durability of the construction body is inferior and that the working environment is deteriorated due to reband loss and dust generation. In recent years, various construction methods and materials such as a semi-dry method and a wet method have been developed to improve the drawbacks of the dry spraying method.

[0003] The semi-dry spraying method is a method in which a part of the required moisture content is previously kneaded with a spray material by a mixer,
This is a construction method in which pneumatic transportation is carried out to a spray nozzle using a dry spray machine, and a solution or suspension containing the remaining water or hardener is added and sprayed at the nozzle (in some cases, just before the nozzle). A disclosure example of this construction method is disclosed in
973, Tokuhei 2-27308, 6-177273, 5-63
Nos. 437 and 5-21866. Although these construction methods have some improvement in terms of prevention of dust generation and reduction of reband loss, since water and materials must be mixed instantaneously at the nozzle part, the mixing degree is not good. And the amount of water is easy to fluctuate. As a result, the adhesion of the spray material, the uniformity of the construction, and the filling property are poor. Among them, as in Japanese Patent Publication Nos. 2-27308 and 6-17273, ultra-fine powder is obtained by previously kneading 1/5 to 3/4 of the amount of water used in the same constituent material with a mixer. Some are dispersed in such a state, and in that state, the material is pneumatically transported using a dry spray machine and sprayed with low moisture content,
Again, the structure of the construction body is not uniform due to insufficient dispersion of the ultrafine powder and the like.

[0004] The wet construction method is a construction method in which all of the necessary construction moisture is kneaded with a spray material in advance and sprayed. In this case, a small amount of an aqueous solution in which a curing modifier or a curing agent is dissolved may be added at the nozzle. Furthermore, this construction method
It is classified into a spraying machine method and a pump method according to the transport means of the material. In the latter case, compressed air is usually added at the nozzle to disperse the material. The method according to the invention basically belongs to the latter category of pumping. Depending on the water content, there are various workability from plastic to slurry. Examples of disclosure of this construction method include JP-B-57-7350 and JP-B-62-21753, and
No. 5 and No. 2-1795. In Japanese Patent Publication No. 57-7350,
Since it is a slurry having a water content of 10 to 20%, a dense construction body suitable for the lining material of the molten metal container cannot be expected. In any of the latter three, the kneaded material is not curable at room temperature and can be built and stored in a factory. In these conventional examples, the maximum particle size is 4 mm or less, and the bonding mode does not depend on the dispersion / aggregation of ultrafine particles. For example, the particle size configuration and the material configuration still follow the configuration of the conventional spray material. In addition, since the compounding composition that enables the storage is adopted, the denseness of the structure of the construction body is also inferior to that of the cast material, particularly the low cement castable refractory, and the durability is considerably poor.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a construction method which incorporates the simplicity of spraying without impairing the durability of casting.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above-mentioned objects, the present inventor has developed a low-cement type casting material which can obtain high density, strength and corrosion resistance with low moisture, by changing the particle size and composition of the material. If it is used as a wet sprayed material, it is possible to obtain a construction body that is much better than conventional spraying work in terms of quality and corrosion resistance and can be compared with the cast material, The present inventors have found that the addition of an alkali silicate solution as a shape-retaining agent at the time of spraying the wet-sprayed material can eliminate the fluidity of the wet-sprayed material and impart shape-retaining properties. I thought.

That is, the wet spraying method of the present invention comprises:
67-97.5% by weight of refractory aggregate with a particle size of 10mm or less, and a particle size of 10μ
m to 25% by weight of a refractory ultra-fine powder of 0.5 m or less and 100% by weight of a refractory composition composed of 0.5 to 8% by weight of alumina cement, and 0.01 to 1.0% by weight of a dispersant is externally added. A low cement castable characterized by being kneaded with water in advance by a mixer to make the workability of pouring is transported to a spray nozzle by a pressure pump, and the compressed air is mixed with the alkali silicate solution [SiO ₂ / R ₂ O
The molar ratio is 2.0 to 3.3 (R ₂ O is an alkali metal oxide,
same as below. ), The specific gravity converted to Be (degree of Baume) at 15 ° C is 40.
0.1 to 1.5% by weight based on 100% by weight of the low cement castable powder.
It is characterized by adding and spraying.

Hereinafter, the present invention will be described in detail. [1] Composition of low cement castable (A) Refractory composition The refractory composition consists of (A-1) refractory aggregate, (A-2) refractory ultrafine powder, and (A-3) alumina cement. Become.

(A-1) Refractory Aggregate The refractory aggregate used in the present invention is electrofused alumina, sintered alumina, bauxite, kyanite, andalusite, mullite, chamotte, rhoite, silica stone, alumina.
It is at least one selected from the group consisting of magnesia spinel, magnesia, zircon, zirconia, silicon carbide, graphite, pitch, and the like, and two or more types can be used in combination as needed. The particle size of the refractory aggregate is 10 mm or less. When the particle size exceeds 10 mm, the pumping performance is deteriorated and the reband loss increases. The amount of the refractory aggregate is the refractory composition.
67 to 97.5% by weight per 100% by weight. The preferred amount of the refractory aggregate is 74 to 94% by weight.

(A-2) Refractory ultrafine powder Examples of the refractory ultrafine powder include amorphous silica, refractory clay, ultrafine silica, ultrafine alumina, ultrafine titania, ultrafine mullite, ultrafine zirconia, and ultrafine powder. At least one selected from the group consisting of chromia, ultrafine silicon carbide, ultrafine carbon, and the like is used, and two or more types can be used in combination as needed. The particle size of the refractory ultrafine powder is 10 μm or less, preferably 1 μm or less. When the particle size exceeds 10 μm, the water reducing effect by the combined use with the dispersant is small, and when the particle size is 1 μm or less, the effect is remarkable.

The compounding amount of the refractory ultrafine powder is 2 to 25% by weight per 100% by weight of the refractory composition. If it is less than 2% by weight, the water reducing effect is small, and if it exceeds 25% by weight, the amount of construction water increases and the shrinkage after firing increases. Preferably 5-20
% By weight.

(A-3) Alumina cement As alumina cement, one kind, two kinds and three kinds of JIS
Species classes are suitable. The amount of the alumina cement is 0.5 to 8% by weight per 100% by weight of the refractory composition. 0.5
If the content is less than 8% by weight, the strength is not sufficiently developed, and if the content is more than 8% by weight, the corrosion resistance is greatly reduced. Preferably 1 to 6% by weight
It is.

(B) Dispersant As the dispersant, alkali metal salts of condensed phosphoric acid and silicic acid such as sodium hexametaphosphate, or organic acids such as carboxylic acid, humic acid, alkylsulfonic acid and aromatic sulfonic acid can be used. Among the alkali metal salts, etc., 1
More than one species can be used. The amount of the dispersant added is 0.01 to 1% by weight based on 100% by weight of the refractory composition having the above constitution. If the added amount of the dispersant is less than 0.01% by weight, a sufficient dispersing effect on the refractory ultrafine powder cannot be obtained, and if it exceeds 1% by weight, an optimum dispersion state cannot be obtained.

As other components, a pot life and hardening time regulator, a thickener, fibers of organic, inorganic, metal and the like, and a dry explosion inhibitor such as metal Al and the like can be blended.

[2] Spraying method The low-cement castable having the above structure is kneaded with water by a mixer. The amount of kneading water is set to such an extent that ordinary pouring is possible. Although the amount of added water is greatly affected by the particle size composition and the porosity of the refractory aggregate, it is generally 5 to 8% by weight based on 100% by weight of low cement castable.
The kneaded material is transported from the mixer to the spray nozzle by a pressure pump, and the spray nozzle performs the spraying operation by adding the alkali silicate solution together with the compressed air.

The alkali silicate solution is used as a shape-retaining agent, but the shape-retaining agent has the effect of eliminating the fluidity of the low-cement castable having the above structure at the moment of spraying and imparting shape retention. . The alkali silicate solution has other shape-retaining properties in that the spraying material has good adhesiveness, does not adversely affect the quality of molten steel (compounds such as phosphorus and boron are not preferred), and is easily available as a liquid. It is superior to the imparting agent.

As the alkali silicate solution, a sodium silicate solution and a potassium silicate solution are widely commercially available. In particular, sodium silicate solution has JIS standards, JIS No. 1, JIS
No. 2, JIS No. 3, etc. can be used. It is preferable to use a sodium silicate solution from the viewpoint of cost.

The SiO ₂ / R ₂ O molar ratio of the alkali silicate solution is 2.0 to 3.3, and the specific gravity in terms of Be (Bome degree) at 15 ° C. is 40 or more. If the Be (degree of Baume) conversion at 15 ° C. of the alkali silicate solution is less than 40, the effect of imparting shape retention is low, and the material drips.

The viscosity of the alkali silicate solution is SiO ₂ / R ₂
It is determined by the O molar ratio, Be (Baume degree) -converted specific gravity and temperature. Even with the same specific gravity, the higher the SiO ₂ / R ₂ O molar ratio and the lower the temperature, the higher the viscosity. Therefore, when the outside air temperature decreases in winter, the viscosity increases and it becomes difficult to spray the solution with the nozzle. In that case,
The alkali silicate solution is heated and supplied. It is also possible to dilute the alkali silicate solution with water to lower the viscosity, but if the diluted specific gravity at 15 ° C. at 15 ° C. becomes less than 40 (Beaming degree), the above-mentioned shape-retaining effect is reduced, The problem of material dripping occurs.

The amount of the alkali silicate solution to be added is 0.1 to 0.1% with respect to 100% by weight of the low cement castable powder.
1.5% by weight. If the addition amount is less than 0.1% by weight, shape retention property due to gelation of alkali silicate cannot be obtained, so that the material drips during spraying. If the content exceeds 1.5% by weight, the coagulation of the alkali silicate solution due to gelation is too fast, so that the adhesion to the base material is deteriorated and the hot strength and corrosion resistance are also reduced. Preferably it is 0.2 to 1.0% by weight.

[0021]

EXAMPLES The present invention will be specifically described by the following examples and comparative examples, but the present invention is not limited thereto.

Examples 1-2, Comparative Examples 1-3 1. Formulation composition of raw cement castable The composition composition shown in Table 1 was used.

2. Execution of construction (A-1) The refractory aggregate, (A-2) refractory ultrafine powder and (A-3) alumina cement were blended in the composition shown in Table 1 to obtain (A).
The refractory composition contains (B) a dispersant and (C) a dry explosion protection agent in Table 1.
The amounts shown in Table 1 were added externally to prepare a low cement castable.

In Examples 1 and 2, the low-cement castable was kneaded by adding water of (E) pre-kneading water content shown in Table 1 and then kneading with compressed air from a spray nozzle.
(D) sodium silicate solution (SiO ₂ / Na ₂ O molar ratio = 2.1
At 0 and 15 ° C., Be (degree of Baume), specific gravity = 50) was externally added in amounts shown in Table 1, and spraying was performed. Further, in Comparative Examples 2 and 3, a dry spray material having the composition shown in Table 1 was used.
It was constructed by the conventional semi-dry spraying method.

After the application, each piece was cut into a predetermined size and dried to obtain a test piece. The amount of water added in the entire spraying construction process is as shown in Table 1 (F).
Further, in Comparative Example 1, a low-cement castable was mixed with water having the water content of (E) pre-kneading shown in Table 1 and kneaded, and poured into a predetermined mold to prepare a test piece. Table 1 also shows the construction method applied in each example and comparative example.

Table 1 Example Comparative Example Component Ratio and Construction Method 1 2 1 2 3 (A) Refractory Composition (A-1) Refractory Aggregate Fused Alumina (> 5 mm) ⁽¹⁾ 17-17-- Fused alumina (under 5 mm) ⁽²⁾ 35 45 35 − − Fused alumina (under 3 mm) ⁽³⁾ − − − 40 40 Fused alumina (under 1 mm) ⁽⁴⁾ 16 25 16 26 30 Magnesia clinker ⁽⁵⁾ − 8 − − 8 Silicon carbide ⁽⁶⁾ 18 − 18 18 − Pitch ⁽⁷⁾ 2 − 2 2 − (A-2) Refractory ultra fine powder Clay ⁽⁸⁾ 1 − 1 3 3 Alumina ultra fine powder ⁽⁹⁾ 5 16 5 5 13 Amorphous silica ⁽¹⁰⁾ 3 1 3 3 1 Carbon black ⁽¹¹⁾ 1 − ¹¹ 1 − (A-3) Alumina cement ⁽¹²⁾ 2 5 2 2 5 (B) Dispersant Sodium hexametaphosphate ⁽¹³⁾ 0.1 0.1 0.1 − − (C) Dry explosion inhibitor Metal aluminum ⁽¹³⁾ 0.5 − 0.5 0.5 − Organic fiber ⁽¹³⁾ − 0.05 − − 0.05 (D) Sodium silicate solution ⁽¹⁴⁾ 0.4 0.5 − − − (E) Reserved Kneading water content ⁽¹⁴⁾ 5.2 5.5 5.2 2.0 2.0 (F) Total water content of sprayed body ⁽¹⁴⁾ 5.4 5.8-1 1.5 12.3 Construction method Invention of the present invention Pour semi-dry method Semi-dry method

Note (1) Particle size 5 mm to 10 mm, unit: wt%. (2) Particle size 1-5 mm, unit: wt%. (3) Particle size 1 to 3 mm, unit: wt%. (4) Particle size 1 mm or less, unit: wt%. (5) Particle size 1 mm or less, unit: wt%. (6) Particle size 150 μm or less, unit: wt%. (7) Particle size 1 mm or less, unit: wt%. (8) Unit:% by weight. (9) Particle size 10 μm or less, unit: wt%. (10) Particle size 1 μm or less, unit: weight%. (11) Particle size 1 μm or less, unit: weight%. (12) Class 1 JIS, unit: wt%. (13) Unit: Weight percentage of outer weight based on 100% by weight of (A). (14) Unit: Outer weight% relative to 100% by weight of the dry powder of (A) + (B).

3. Evaluation (1) Evaluation on test pieces After measuring the bulk specific gravity of each test piece at 1000 ° C. and 1500 ° C., the bending strength and the erosion index were measured under the following conditions. Table 2 shows the results.

Bending strength (kgf / cm ² ): Bending strength after firing (1000 ° C. and 1500 ° C.) and hot bending strength (1500 ° C.) were measured based on JIS-R2553. Erosion index: In Example 1, Comparative Examples 1 and 2, blast furnace slag was used as an erosion material, and the erosion test was carried out at a melting temperature of 1500 ° C. for 5 hours. On the other hand, in Example 2 and Comparative Example 3, converter slag (the molar ratio of CaO / SiO ₂ was 4.2) was used as the erosion material, and 1650 was used.
The solution was kept at a melting temperature of 5 ° C. for 5 hours, and a rotary erosion test was performed.
After the rotation erosion test, a refractory sample was taken and the erosion thickness was measured. The obtained erosion thickness was converted into a value per time, and for Comparative Examples 1 and 2, the measured value of Example 1 was 100.
For Comparative Example 3, the measured value of Example 2 was set to 100, and the relative value of the erosion thickness of each sample was set as the erosion index.

Table 2 Example Comparative Example Item 1 2 1 2 3 Bulk specific gravity 1000 ° C 2.85 2.95 2.90 2.31 2.38 1500 ° C 2.88 2.90 2.93 2.21 2.30 Flexural strength after firing 1000 ° C ⁽¹⁾ 61 83 78 23 45 1500 ° C ⁽¹⁾ 125 210 160 150 150 Hot bending strength 1500 ℃ ⁽¹⁾ 31 35 37 9 13 Erosion index ⁽²⁾ 100 100 82 375 315 Note (1) Unit: kgf / cm ² . (2) An index value when the value of Example 1 or Example 2 is set to 100.

(2) Practical evaluation Example 1 and Comparative Examples 1 and 2 were applied to an actual blast furnace main gutter,
The average erosion thickness per 1000 tons of hot metal was measured, and the erosion rate (mm / 1000t hot metal amount) was determined. The results are shown in Table 3.

Table 3 Example 1 Comparative Example 1 Comparative Example 2 Melting Speed (mm / 1000t Hot Metal Amount) 5.9 5.2 19.3

Example 1, Comparative Example 1 and Comparative Example 2 are examples in which the refractory aggregate is of the Al ₂ O ₃ —SiC—C type. This is a comparison of the differences. Example 1 is slightly inferior to the casting of Comparative Example 1, but is much better than the conventional semi-dry spraying of Comparative Example 2. Example 2 and Comparative Example 3 is an example of the aggregate is Al ₂ O ₃ -MgO system.
Again, Example 2 is much better in quality and corrosion resistance than Comparative Example 3.

[0034]

According to the present invention, a low-cement castable having the particle size and composition of a normal pouring material is kneaded with water in advance by a mixer to make it workable for pouring. By performing spraying by adding a small amount of an alkali solution as a shape-retaining agent, it is possible to obtain a construction body which is much more excellent in quality and corrosion resistance than conventional spraying construction and can be compared with a cast material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Vincent de Restivo, Siotte Parkway, 2700, Columbus, Ohio, USA 2700 (72) Inventor John A. Walkman, Siot Parkway, 2700, Columbus, Ohio, USA

Claims (2)

[Claims] 1. A refractory aggregate 67-97.5% by weight having a particle size of 10 mm or less, and a refractory ultrafine powder 2-25% by weight having a particle size of 10 μm or less,
Refractory composition comprising 0.5 to 8% by weight of alumina cement
A low cement castable, characterized by adding 0.01 to 1.0% by weight of a dispersant to 100% by weight, is kneaded with water in a mixer in advance to make it workable by pouring. It is transported to a spray nozzle, and the silicate alkali solution [S
When the iO ₂ / R ₂ O molar ratio is 2.0 to 3.3 (R ₂ O is an alkali metal oxide), the specific gravity in terms of Be (degree of Baume) at 15 ° C. is
40 or more] as a shape-retaining agent, and 0.1 to 1.5% by weight of the low-cement castable powder is externally added to 100% by weight of the low-cement castable powder, followed by spraying. 2. The wet spraying method according to claim 1, wherein the alkali silicate solution is a sodium silicate solution or a potassium silicate solution.