JPS5838388B2 - Construction method of castable refractories - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing a castable refractory, and in particular, the present invention relates to a method for constructing a castable refractory, and in particular, the present invention relates to a castable refractory made of one or two of basic refractories, neutral refractories, and acidic refractories. This invention relates to a construction method for castable refractories.

Conventionally, castable refractories have their particle size adjusted, usually 10 to 17 g of hydraulic alumina cement is added, and when mixed with water and installed at the desired location,
It is a refractory that begins to harden in about 0 to 60 minutes, is sufficiently hardened after about 6 hours, and reaches its final strength after about 24 hours.

Therefore, castable refractories are widely used because they are not only easy to construct, but also have performance similar to that of firebricks.

However, in castable refractories, the acicular crystals of CaO-Al203.10H20, which is alumina cement hydrate, change to granular crystals at around 900'C while the temperature rises to the operating temperature after construction, and the strength not only decreases. Because the dehydration reaction of hydrates occurs at relatively high temperatures, explosion phenomena are likely to occur during rapid heating, and dry heating must be carried out extremely carefully after construction until reaching the final use temperature. There are drawbacks.

Furthermore, since CaO contained in alumina cement is unavoidably mixed into the castable refractory after construction, there is a drawback that a decrease in fire resistance is unavoidable due to this CaO.

The purpose of the present invention is to provide a construction method for castable refractories that eliminates and improves the above-mentioned drawbacks of conventional castable refractories after construction. Addition and mixing of sodium silicofluoride with a diameter of 0.2 to 1 φ of the weight of powder and granules consisting of one selected from among them, or a basic refractory and a neutral refractory, or a neutral refractory and an acidic refractory. To 100 parts by weight of the mixture, a sodium silicate concentration of 10 to 25φ and an orthophosphoric acid concentration of o. The above object can be achieved by a method of constructing a castable refractory, which is characterized in that 6 to 50 parts by weight of an aqueous solution of i to 1.5 φ is added and mixed.

Next, the present invention will be explained in detail.

Conventional methods for constructing water glass-based castable refractories are well known, in which water glass and sodium silicofluoride or ammonium fluorosilicate are added to and mixed with refractory material powder and hardened. is being constructed.

The curing mechanism of the refractory in this case is based on the reaction of the following formula (1).

3 n Si02 produced by the above reaction functions as a bond, for example, at a sodium silicate concentration of 15 to 20
When 12 to 18 parts by weight of an aqueous solution of polysilicon is added and mixed to 100 parts by weight of refractory powder containing two pieces of sodium silifluoride, it hardens in about 10 minutes and has a compressive strength of 100 kg/cI.
A cured product of IL is obtained.

At this time, it is necessary that two volumes of sodium silicofluoride be present in the refractory powder, and if the amount is less than this, the strength of the cured product will decrease rapidly.

However, a cured product obtained by adding 2 φ or more of sodium silicofluoride has the disadvantage that harmful fluorine gas is emitted during heating and drying.

According to the present invention, in order to eliminate the above-mentioned drawbacks, if a small amount of orthophosphoric acid, which is a weak acid, is added in advance to a water glass aqueous solution within a certain range, a state in which SiO2 gel is easily formed due to the reaction of the above-mentioned formula (2) can be obtained. When this aqueous solution is added to and mixed with refractory powder and granules containing a small amount of sodium silicofluoride, it can be cured within a predetermined time range of 30 minutes to 4 hours, and harmful fluorine gas The present invention has been perfected by finding that the occurrence of can be ignored.

Next, the experimental results shown in FIG. 1 regarding the relationship between the concentration of orthophosphoric acid in a water glass aqueous solution and the curing time of castable refractory powder will be explained.

The concentration of orthophosphoric acid in the aqueous solution of sodium silicate concentration 18 was set to 0.
The curing time was measured by adding 13 parts by weight of the solution varying within the range of 1 to 1.5 to 100 parts by weight of combined mullite powder containing 0.5φ of sodium silifluoride.

As can be seen from the figure, the orthophosphoric acid concentration is 1. The curing time is about 1 hour in the case of a solution with 0% concentration, and about 4 hours in the case of a solution with an orthophosphoric acid concentration of 0.2φ.

On the other hand, the concentration of orthophosphoric acid in the solution was kept constant at 0.85φ, and the amount added was also kept constant at 13 parts by weight per 100 parts by weight of the powder,
FIG. 2 shows the results of varying the weight percentage of sodium silicofluoride in the powder.

According to the figure, the curing time is approximately 1 hour when the amount of sodium silifluoride is 1.0 yen, but when the amount of sodium silifluoride is 0.2 φ, the curing time is approximately 4 hours.
It turns out it's time.

The reason for limiting the weight of the sodium silifluoride added to the refractory powder in the present invention is that the sodium silicofluoride is 0% of the weight of the powder. If it is less than 2%, cracks will occur when drying after construction, while if it is more than 1φ, not only will the strength after construction decrease, but also more harmful fluorine will be generated during drying. It is necessary to limit it within the range of .2 to 1 rice cake.

In the present invention, the reason why the concentration of sodium silicate in the aqueous solution is limited is that if the concentration of sodium silicate is less than 10 mm, the amount of raw material of nsi02 that will become a bond after construction will be small and the curing will be weak, whereas if it is more than 25φ, the concentration of sodium silicate in the aqueous solution will be limited. This is because the fluidity decreases and it becomes difficult to mix uniformly with the refractory powder and granules, resulting in localized uneven hardening after construction, and the concentration needs to be within the range of 10 to 25 degrees. be.

In the present invention, the reason for limiting the concentration of orthophosphoric acid in the aqueous solution is that if the concentration is less than 0.1φ, the amount of gel produced by reaction with sodium silicate in the aqueous solution is extremely small, resulting in an excessively long curing time. On the other hand, 1.
This is because if the amount is more than 5, the curing time is too short and it is inconvenient for construction, and the orthophosphoric acid concentration in the aqueous solution is 0.1 to 1.5
Must be within the range.

In the present invention, the reason for limiting the amount of the aqueous solution added to the mixture of powder and silicofluoride is that if the aqueous solution is less than 6 parts by weight per 100 parts by weight of the mixture, even if this aqueous solution is added to the mixture and mixed. This is because it is difficult to apply because it does not form a wet adhesive state, and on the other hand, if the amount is more than 50 parts by weight, when it is added to the mixture, the fluidity becomes too thick and it becomes difficult to apply. It is necessary to keep it within the range of 50 parts by weight.

In the present invention, basic refractories, neutral refractories, and acidic refractories are targeted as castable refractories, and the basic refractories are magnesia, dolomite, or spinel refractories, and the neutral refractories are high Alumina, chromium, zircon, or silicon carbide refractories can be advantageously used, and as the acidic refractory, silica, silica, or clay refractories can be advantageously used.

In addition, when using two types of the above-mentioned refractories, granules of a basic refractory and a neutral refractory, or granules of a neutral refractory and an acidic refractory can be used.

However, if a basic refractory and an acidic refractory are used in combination, the fire resistance will be significantly lowered, so they cannot be used.

In the present invention, the particle size of the castable refractory powder is adjusted depending on the purpose of use, and the particle size of the powder and granule whose particle size has been adjusted is solid, hollow, or porous. More than one species can be used.

Next, the present invention was compared with the comparative examples for the examples, and for 100 parts by weight of the materials shown in Tables 1 and 2, the concentration of sodium silicate was 10 to 13φ, and the concentration of orthophosphoric acid was 0.3 to 0. 5% aqueous solution (this aqueous solution was made by adding water to orthophosphoric acid to make the predetermined orthophosphoric acid concentration, and then No. 3 water glass was added to give the predetermined concentration) 2
When 5 to 35 parts by weight is added and used for hot repair of hot spots on the inner wall of an electric furnace, the adhesion is better than that of conventional spraying materials mixed with sodium silicate powder, and the rebound loss is within the range of 50 liters). Met.

In addition, the durability can withstand 2 to 3 charges, which is about 2 times lower than conventional products.
It was twice as durable and could be sprayed significantly thicker.

Next, the present invention was carried out using the materials and weights shown in Table 3 below.

The particle size distribution of the material having the weight composition shown in Table 3 was as shown in Table 4 below.

For 100 parts by weight of the materials shown in Tables 3 and 4, an aqueous solution with a sodium silicate concentration of 16 to 18φ and an orthophosphoric acid concentration of 0.3 to 0.8% (this aqueous solution is prepared by adding water to orthophosphoric acid to obtain a predetermined orthophosphoric acid concentration) After that, No. 3 water glass was added to obtain a predetermined concentration.

) After adding and mixing 10 to 20 parts by weight, the mixture was applied to a molten steel pot by troweling.

On the other hand, for comparison, trowel coating using a conventional castable refractory material using alumina cement shown in Table 5 was applied to a molten steel ladle.

For 100 parts by weight of the materials shown in Tables 6 and 7, the concentration of sodium silicate is 22 to 23, and the concentration of orthophosphoric acid is 0.2 to 0.5.
% aqueous solution (this aqueous solution was made by adding water to orthophosphoric acid to make a predetermined orthophosphoric acid concentration, and then No. 3 water glass was added to give a predetermined concentration.

) 10 to 15 parts by weight were added and kneaded, and then poured into the side wall of a molten steel ladle.

On the other hand, as a comparative example, a conventional castable refractory material using alumina cement was poured into the side wall of a molten steel ladle.

As a result, while in the comparative example explosion occurred during drying, in the present invention there was no drying crack and rapid drying was possible.

According to the present invention, compared to the conventional method used for comparison, the life of the molten steel ladle is 1.5 times longer, and according to the present invention, not only is there less drying cracking, but also rapid drying. It is also possible to shorten the drying time, and for example, complete dehydration can be achieved in 1 hour at 170° C. without any loss in strength.

Further, according to the present invention, the durability is high because the impurity is N.
a20 0.6%, P20, o. This is because it is extremely small at 1% and does not reduce the fire resistance.

As described above, according to the construction method of the present invention, it is possible to dry in a short time and has high durability, so compared to the conventional method,
Very good.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the concentration of orthophosphoric acid in an aqueous solution of sodium silicate and orthophosphoric acid added to a mixture of refractory powder and silicofluoride and the hardening time of the powder. The figure is a diagram showing the relationship between the amount of sodium silifluoride in a mixture of refractory powder and sodium silifluoride and the hardening time of the powder.

Claims (1)

[Claims] 1. Falling down of basic refractories, neutral refractories, and acidic refractories
0.2 to 1φ of the weight of seeds or powders consisting of basic refractories and neutral refractories or neutral refractories and acidic refractories.
To 100 parts by weight of a mixture of 100 parts by weight of sodium silicate fluoride was added and mixed, the concentration of sodium silicate was 10 to 25 and the concentration of orthophosphoric acid was 10 to 25 parts by weight. i~1.
A method for constructing a castable refractory, which comprises adding and mixing 6 to 50 parts by weight of an aqueous solution.