JP2000327439A - Basic repairing material for hot wet spraying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a basic repairing material for hot wet spraying excellent in hot adhesion and also having fine structure and excellent in slag penetration resistance, abrasion resistance and volume stability. SOLUTION: In the basic repairing material for hot wet spraying, the composition consisting of the aggregate having 5 to 50 wt.% magnesia/calcia clinker having MgO/CaO wt. ratio of (70/30) to (85/15) and the balance alumina, magnesia and silica and 8 to 12 wt.% water per total weight as outer material are kneaded to obtain the softness capable of forcibly sending by pump, and the material is sprayed by adding the curing accelerator having >=pH 10 and <=200 c.p. viscosity at a spray nozzle part. In such a case, 5 to 10 wt.% alumina having 1 to 0.074 mm particle size is compounded in the total composition and the fine powder of the magnesia and the silica having less than 0.074 mm particle size are compounded so that MgO/SiO2 wt. ratio may be 5 to 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal container for melting,
In particular, the present invention relates to a basic repair material used for repairing a large immersion pipe having an inner diameter of 1 m or more of a secondary refining vessel such as a molten steel pot or RH or DH by hot wet spraying.

[0002]

2. Description of the Related Art Conventionally, methods for repairing refractories of various melting furnaces for iron and steel making, particularly for hot repair of secondary refining vessels, include dry spray repair, press-fit repair, patching repair, wet spray repair, and the like. Method has been applied.

[0003] Dry spray repair is a method in which an amorphous material in a dry powder state is pneumatically fed, and a binder or a quick-setting agent and water are added to and sprayed on a pressure-feeding pipe (hose) or a spray nozzle portion during the feeding. Worked in cold and hot,
It is widely used because it can be constructed in a relatively short time and with a small number of people.

[0004] However, in the dry spray repair, since a large amount of water is added, a dense construction body cannot be obtained, and a large amount of a flux component as a binder is contained.
Lamination is easily formed on the construction body. Therefore, there is a problem that the slag is inferior in resistance to slag infiltration and has a low hot strength, so that it is peeled and worn in an early stage of operation.

[0005] Press-fitting is a method in which an irregular-shaped material kneaded with water is fed through a hose into a cold or hot repair area by press-fitting the material. Due to the low moisture and the dense structure, it has a high service life record. However, hot repair of immersion pipes such as RH and DH requires the installation of a frame on the side of the immersion pipe, so that the scale of repair becomes large, and it takes time to cure and dry the construction body.

[0006] Furthermore, patching is a method in which a highly plastic amorphous material kneaded in advance with water is applied by hand to a repaired part. However, when hot repair of a large immersion pipe is considered, the work time and safety are reduced. Unsuitable from the surface.

Further, in the repair method by wet spraying, an irregular refractory material kneaded in advance with an amount of water necessary for construction is pressure-fed, and a quick-setting agent is supplied to a pressure-feeding pipe (hose) or a spray nozzle part during the pressure-fed. It is a method of adding and spraying, it is possible to perform construction without a frame and for a short time, and the construction body can be expected to have a denser structure than the dry type.
There is no example in which the same method was applied to a dip tube of a secondary smelting container such as DH hot.

On the other hand, from the viewpoint of the material composition of the amorphous refractory, the addition of magnesia and calcia clinker has been generalized in order to improve slag penetration resistance and spalling resistance to basic slag.

Further, Japanese Patent Application Laid-Open No. 9-100172 discloses a casting method in which ultrafine silica is added as a binder and a fluidity imparting agent in order to improve the fluidity of an amorphous refractory using magnesia and calcia clinker. Materials are disclosed.

However, the addition of the silica component to magnesia-calcia clinker promotes sintering, so that the hot shrinkage increases, the hot strength decreases, and the resistance to abrasion in molten steel may decrease. In addition, when applied to the repair of the inner wall of a dip tube, there is a possibility that the material is peeled off because there is no support for supporting the sprayed material.

[0011]

The problem to be solved by the present invention is to improve the hot adhesion of the basic repair material for hot wet spraying, achieve a fine structure of the construction body, It is an object of the present invention to obtain slag penetration resistance, abrasion resistance, and volume stability, to improve resistance to abrasion in molten steel, and to prevent detachment of a construction body due to firing shrinkage.

[0012]

The present invention analyzes the problems when applied to hot repair by the wet spraying method, and thereby obtains a basic repair material for hot wet spraying which solves the above-mentioned problems. Was.

First, the problem of the hot wet spraying method is the adhesion of the material. When the surface to be sprayed has a high temperature of 700 ° C. or more, when the sprayed material reaches the surface to be sprayed, the material in the material is removed. Water evaporates due to the heat received from the spray surface, and the generated steam may push the material and not adhere to the spray surface.

Further, since the material discharged from the nozzle is already added with the quick-setting binder, the water evaporates before reaching the surface to be sprayed, and hardens due to evaporation.

Further, as for the material, although the MgO-CaO material has the above-mentioned drawbacks, the large immersion pipe used for the secondary refining vessel is immersed in the high basicity slag. MgO-CaO effective for permeability
Quality is advantageous.

That is, the basic repair material for hot wet spraying of the present invention has a MgO / CaO weight ratio of 70/30 to 85.
/ 15 of 5 to 50% by weight of magnesia and calcia clinker, the balance being alumina, magnesia and silica aggregate, and the alumina has a particle diameter of 1 to 0.074 m
m is blended in a total weight of 5 to 15% by weight,
The magnesia and the silica are blended with fine powder having a particle diameter of less than 0.074 mm so that the weight ratio of MgO / SiO ₂ is 5 to 50.

When the weight ratio of MgO / CaO is higher than 85/15, the amount of free CaO in the clinker is small, and the effect of suppressing permeation of slag is sufficiently exhibited in the magnesia / calcia clinker used in the present invention. It becomes difficult to do. Further, the MgO / CaO weight ratio is 70/3.
In a range lower than 0, the amount of Ca ²⁺ eluted into water after kneading increases due to an increase in the free calcia component, so that the material may be solidified during the standby time before spraying.

In the case of hot work at 700 ° C. or more,
Moisture evaporates instantaneously on the spray surface, but if the spraying thickness increases, the magnesia-calcia clinker digests due to water vapor generated inside the construction body, and there is a possibility that the construction body will crack. Accordingly, the magnesia-calcia clinker used is, for example, MgO and Ca disclosed in JP-A-5-294713.
When the total amount of O and Fe ₂ O ₃ is 97% by weight or more,
0% by weight or more, Fe ₂ O ₃ is 0.2 to 5% by weight,
It is preferable to use a raw material in which the clinker surface in which iO ₂ has a chemical component of 0.5 to 3% by weight is coated with a low-melt or phosphate to improve digestion resistance.

The reason why the amount of magnesia and calcia clinker is set to 5 to 50% by weight is that when the amount is less than 5% by weight, the effect of suppressing slag permeation is thin, and when the amount exceeds 50% by weight, a large amount of coagulated ions are dissolved during kneading. This is because the properties are significantly reduced.

When the repairing material for spraying of the present invention is applied to repairing the inner wall of a dip tube, the shrinkage of the construction body increases the risk of falling off. Therefore, it is necessary to impart volume stability to the construction body. For this purpose, alumina, magnesia and silica are blended in addition to magnesia and calcia clinker.

When alumina is used as fine powder having a particle diameter of less than 0.074 mm, MgO—CaO—Al ₂ O ₃ —Si
A low O ₂ melt is likely to be generated, which tends to cause firing shrinkage. On the other hand, when the particle diameter exceeds 1 mm, the spinelization reaction hardly occurs, and the effect of the addition is reduced. Therefore, alumina has a particle size of 1 to 0.074.
It is effective to use those having a range of 5 mm to 15% by weight. If the amount is less than 5% by weight, the amount of spinel produced is small, and the effect of the production is small. On the other hand, if the amount exceeds 15% by weight, not only does the corrosion resistance decrease, but also the degree of expansion due to too much spinel formation increases, and the risk of cracking increases.

Magnesia is a high-expansion aggregate excellent in slag infiltration property, but its tissue is weakened due to repeated heat history. Therefore, in the present invention, the particle diameter is 0.074
By using a material having a diameter of less than 1 mm with alumina, a spinel reaction with magnesia is formed.At the same time, expansion is achieved, and volume stability is achieved.At the same time, the structure near the operating surface is densified, and slag infiltration is further improved. It has an inhibitory effect.

Further, silica is a primary particle generally used for a casting material, and has a particle diameter of 0.025 μm or more.
50 μm amorphous silica, added to impart fluidity and form cohesive bonds with magnesia. The amount used is such that the weight ratio of MgO / SiO _{2 to} the amount of MgO is 5 in the fine powder portion having a particle size of less than 0.074 mm.
~ 50. If the weight ratio exceeds 50, the generated cohesive bonds are small and the strength of the construction body is reduced. Further, when it is less than 5, the amount of silica is too large, so that not only corrosion resistance is lowered, but also MgO—CaO—Al ₂ O ₃ —S
Low melt of iO ₂ is easily generated, hot strength is reduced,
Since the firing shrinkage is large, the volume stability is also lacking.

The kneading water content of the spray repair material according to the present invention is in the range of 8 to 12% by weight on the outside. If the content is less than 8% by weight, in hot working at 700 ° C. or higher, moisture in the material evaporates during flight during spraying, and the material hardens before adhering to the projectile. Further, even if it adheres to the projectile, the construction body becomes too dense, and the construction body falls off due to steam generated on the adhered surface. On the other hand, if the content exceeds 12% by weight, the number of air holes in the structure increases, and steam easily escapes into the inside of the construction body. .

Further, the quick-setting admixture is a liquid and has a function of mixing with a spraying material in a short time to agglomerate the peptized material into a viscous plastic material. Injected with. Solutions such as silicates, aluminates, chlorides, hydroxides and sulfides having such a function are used. However, with a quick setting agent having a pH of less than 10,
Because of its low strength development, it easily falls off after adhesion. The viscosity is 200 c. p. The following is preferable, and the viscosity of the liquid is 200
c. p. When the temperature exceeds the limit, it is difficult to perform stable ejection, mixing with the material at the nozzle tip becomes insufficient, and the spray may not hang down after being sprayed on the projectile.

Further, in the spray repair material of the present invention, it is possible to use a dispersant used for a general casting material. That is, condensed phosphates, polycarboxylates, humates, alkyl sulfonates, aromatic sulfonates, lignin sulfonates, and the like, and one or more substances having the same effects as those described above. More than species can be used. The amount of use may be in a usual use range, for example, about 0.005 to 1.0% by weight per 100% by weight of the refractory aggregate.

Further, organic or inorganic fibers can be added to the spray repair material of the present invention for the purpose of improving air permeability and preventing separation of fine powder.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to examples.

Table 1 shows the composition and properties of the magnesia and calcia clinker used. Clinker B is an aggregate falling within the scope of the present invention.

The analysis of the chemical components of clinker is carried out by a fluorescent X-ray analysis method based on the Gakushin method. Apparent porosity and bulk specific gravity were measured by a vacuum suction method.

[0031]

[Table 1] Table 2 shows the accelerator used. The quick setting agent a is potassium silicate, the quick setting agent b is sodium silicate, the quick setting agent c is a calcium chloride solution, and the quick setting agent a falls within the scope of the present invention. The pH and viscosity (cp) are values measured by a pH meter and a B-type viscometer, respectively.

[0032]

[Table 2] Using the materials shown in Tables 1 and 2, after kneading the materials with a cement mixer (9.1 (1) of JISR5201), a predetermined amount of a quick-setting admixture was added, and the mixture was kneaded for 30 seconds and inserted with a metal rod. A sample was prepared by. Tables 3 and 4
And 5.

Each of the composition samples was subjected to an actual test using a dip tube for DH having an inner wall surface of 700 ° C.
5 m), spray repair was performed with a thickness of about 80 mm, and the characteristics were examined.

The numerical values showing the characteristics in the table were obtained by the following methods.

The residual expansion rate was measured on a sample fired at 1500 ° C. for 3 hours in accordance with (JISR 2554 Test Method for Linear Change of Castable Refractories).

The hot bending strength was measured by using a test piece having a cross section of 40 mm square and a length of 160 mm, and measuring the three-point bending strength in an electric furnace at 1500 ° C. and a span of 100 mm.

Regarding the corrosion resistance, CaO / SiO ₂ =
A slag rotation erosion test was performed at 1650 ° C. for 4 hours using a slag of 3.0 (molar ratio), and the erosion index was a value obtained by comparing the erosion rate of Comparative Example 1 with 100 as the erosion index.

The adhesion ratio was measured by the ratio of the weight attached to the total construction weight, that is, the weight that did not adhere to the total construction weight.

The number of durable charges is based on the construction area
This is the number of immersions until the construction body remains in an area of 10% or more after immersion.

In Examples 1 to 5 of the present invention shown in Table 3, magnesia and calcia clinker corresponding to the present invention were used in an amount within the range of the present invention, and good corrosion resistance, volume stability and high heat were obtained. It has inter-strength and shows 4 to 5 times the durability in a real machine test as compared with Comparative Example 7 which is a conventional dry spray material.

[0041]

[Table 3] On the other hand, Comparative Examples 1 and 2 show examples using magnesia-calcia clinker containing a large amount of CaO component. In this case, since the amount of Ca ²⁺ eluted is large, the pot life is short even with a small amount of addition, and there is a possibility that the material may aggregate in the hose during the pressure feeding operation, so that it cannot be applied.

Comparative Examples 3 and 4 are examples in which magnesia-calcia clinker containing a small amount of CaO is used. However, since the amount of free CaO in the clinker is small, the effect of suppressing slag infiltration is thin, and the corrosion resistance is extremely low. Deteriorated, even in actual machine tests, Comparative Example 7 which is a conventional dry spray material
Of the dry spraying material was obtained.

In Comparative Example 5, the amount of magnesia and calcia clinker was smaller than the range of the present invention, and the corrosion resistance was deteriorated and the durability was not good.

In Comparative Example 6, magnesia-calcia clinker corresponding to the present invention was used. However, since the amount of use was excessive, the pot life was short as in Comparative Examples 1 and 2, and construction was difficult. .

In Examples 6 to 10 shown in Table 4, the amount of added alumina and the particle size were 0.074 mm within the range specified in the present invention.
An example is shown in which the MgO / SiO ₂ ratio of magnesia and silica is changed to less than. All the examples showed good durability in actual machine tests.

[0046]

[Table 4] Comparative Examples 8 to 10 shown in the same table show examples in which a material having a range smaller than the specified alumina particle size was used, but none of them exhibited the effect of volume stability due to spinel formation, and rather sintering proceeded. Due to shrinkage, the service life in the actual furnace was not good.

Similarly, in Comparative Example 11, if the amount of alumina is less than that of the present invention, the amount of spinel produced is too small.
The effect has not appeared.

In Comparative Example 12, since the amount of alumina was larger than the specified amount according to the present invention, not only the corrosion resistance was lowered, but also the expansion due to spinel formation became too large, causing cracks in the actual furnace, resulting in poor service life.

In Comparative Example 13, the MgO / SiO ₂ ratio was 50
Larger, less cohesive bonds were generated, resulting in lower hot strength, and the amount of ultrafine amorphous silica was too small, making it difficult to pump in a short time, making implementation impossible.

Comparative Example 14 shows an example in which the MgO / SiO ₂ ratio is 4.5, which is smaller than the specified range of the present invention. In this example, the low melting of _{MgO-CaO-Al 2 O 3} -SiO 2 is easily generated, corrosion resistance, hot strength is low and the service is poor.

Table 5 shows the effect of the added water during the construction. With the added water in the case of Examples 15 and 16 shown in the same table, favorable application results are shown in both the adhesion rate and the durability.

[0052]

[Table 5] In Comparative Example 15 in the same table showing that the amount of added water was small, the construction body was too dense, and dropped by more than half in 1-2 minutes after spraying.

Comparative Example 16 shows a case where the amount of added water is too large. In the case of this example, although the adhesion rate was good, the structure was coarse and the corrosion resistance and the hot strength were at low levels, and the durability was low.

Comparative Example 17 uses a quick-setting agent having a viscosity higher than the range of the present invention. The material at the nozzle and the quick-setting agent are not sufficiently mixed, and the quick-setting agent drips even when sprayed on the projectile. It did not adhere. In Comparative Example 18, although a quick setting agent having a pH lower than that of the range of the present invention was used, since the strength was slowly developed, once it adhered, it was peeled off and dropped off within a few minutes.

[0055]

The basic repair material for hot wet spraying of the present invention can be applied in a short time, and has a higher hot adhesion, slag penetration resistance, abrasion resistance, and volume compared to conventional dry spraying materials. It is excellent in stability and can extend the life of a large immersion tube and reduce the work load.

Continued on the front page (72) Inventor Kazuhiko Kawasaki 1-1, Higashihama-cho, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Kurosaki Ceramics Co., Ltd. 1-1 Hatabicho, Nippon Steel Corporation Yawata Works (72) Inventor Yasujiro Matsui 1-1 Hibatamachi, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture F-term in Yawata Works, Nippon Steel Corporation (reference) 4G033 AA02 AA03 AA04 AA06 AA24 BA02

Claims (2)

[Claims] 1. The method according to claim 1, wherein the weight ratio of MgO / CaO is 70 / 30-
85/15 magnesia calcia clinker 5-5
0% by weight, with the balance being a mixture of alumina, magnesia, and silica, kneaded in advance with the necessary amount of water to make the pump pumpable soft, A repair material to which a quick-setting agent is added and sprayed at a spray nozzle portion, wherein the alumina in the composition has a particle diameter of 1 to 0.074 m.
m is 5 to 15% by weight with respect to the total weight, and the magnesia and silica have a particle size of 0.074.
Fine powder having a weight ratio of MgO / SiO ₂ of 5 to 50 mm or less.
A basic repair material for hot wet spraying that is formulated to have the following ratio. 2. The kneading water content is 8 to 8 in total over the whole amount.
In the range of 12% by weight, the quick setting agent has a pH of 10 or more,
Viscosity 200c. p. The basic repair material for hot wet spraying according to claim 1, wherein the following material is used.