JP2752672B2 - Irregular refractories - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an amorphous refractory, and more particularly to an amorphous refractory whose quality is prevented from deteriorating over time for a long period of time.

[Related Art] A castable refractory is composed of a refractory raw material as a main component and a binder for giving strength to a refractory construction body after construction. These raw materials are mixed in powder form, and are temporarily stored until construction (about 10 to 100 days including the transportation period). Further, as the binder for the amorphous refractory, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, sodium ultrapolyphosphate, or the like is used.

JP-A-62-91472 discloses that, for the purpose of improving workability, strength, and fire resistance, a refractory composition containing alumina cement, ultrafine silica powder, and sodium phosphate is put into a mixer and mixed with stirring. A refractory composition is disclosed.

[Problems to be solved by the invention]

A powdery amorphous refractory such as a castable refractory usually contains about 0.3% by weight of water, and the binder has a hygroscopic property. Therefore, the binder deteriorates with time during the storage period due to the moisture contained in the raw material itself or the moisture absorbed by the binder, or reacts with Ca ions in cement,
In some cases, it is not possible to maintain qualities such as flow characteristics and hardening characteristics according to the material design.

In order to prevent the above-mentioned irregular refractories from changing over time, raw materials and binders of the irregular refractories have low hygroscopicity and are selected and used with little chemical change. At the present time, the reaction with the water contained in the raw material and the sodium phosphate or the Ca ion in the alumina cement, and the change with time due to the oxidation and decomposition of the binder are inevitable. Therefore, the fluidity is reduced during kneading and construction of amorphous refractories, casting cannot be performed, uniform filling cannot be performed at the time of vibration construction, it can be dense and dense with the construction body structure, hardening time is long It was too much, and coarse particles and fine powder were separated from each other, resulting in problems such as an inhomogeneous structure and non-hardening. In addition, the contents disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 62-91472 are intended only to improve workability, strength, and fire resistance.
It has a different purpose from the application described below,
The details such as conditions are significantly different, and the difference in effect is also significantly different.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a refractory in which the deterioration of a binder due to moisture is prevented.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a refractory raw material having a particle size adjusted by mixing one or more alumina cements and hydrophobic silica ultrafine powder as a binder with a stirring blade having a peripheral speed of 100 m.
/ Refractory to which one or more kinds of sodium phosphates added by stirring for 5 minutes or more with a mixer of more than / minute, the amount of the hydrophobic silica ultrafine powder is as follows:
The content is 0.5 to 6% by weight of the above sodium phosphate.

(Operation)

The sodium phosphate is used as a binder and at the same time as a water reducing agent, and is added to give fluidity to the refractory during construction. The appropriate amount of sodium phosphate added is 0.03 to 0.5% by weight based on the total amount of the refractory raw materials. If the amount is less than 0.03% by weight, the water reducing effect is small and the required fluidity cannot be obtained.
Further, even if it is used in excess of 0.5% by weight, no improvement in characteristics is observed, and it is not necessary to use it. As sodium phosphate,
Sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, and sodium ultrapolyphosphate can be used, but since these sodium phosphates have hygroscopicity, they are coated with ultrafine hydrophobic silica powder in the present invention to prevent moisture absorption. Perform processing.

Ultrafine hydrophobic silica powder is high purity SiO ₂ (SiO ₂ > 99.8%)
Is an ultrafine powder (temporary particle average diameter: about 20 nm), and the analysis values are as shown in Table 1 on the next page.

The coating treatment with sodium phosphate is performed by mixing sodium phosphate and ultrafine hydrophobic silica powder and stirring them vigorously under normal pressure or reduced pressure. The amount of the ultrafine hydrophobic silica powder is 0.5 to 6% by weight of sodium phosphate. The stirring conditions are such that the peripheral speed of the stirring blade is 100 m / min or more and the stirring time is 5 minutes or more by a mixer such as a Henschel mixer. Stirrer blade speed is 10
When the mixing time is less than 0 m / min or the stirring time is less than 5 minutes, only insufficient coating can be performed, which is not preferable.

FIG. 2 shows the structure of sodium phosphate particles coated with ultrafine hydrophobic silica particles by the above treatment.
The figure is. The structure of sodium phosphate particles not subjected to the above treatment is shown. Comparing the two, it can be clearly understood that the coating layer is formed by the present invention.

Commercially available products can be used as the alumina cement used in the present invention. The amount of the alumina cement used is preferably about 1 to 8% by weight, and if it is less than 1% by weight, sufficient strength cannot be obtained in the construction body, which is not preferable. It is not preferable. As the refractory raw material, various materials such as alumina, silica, chamotte, zircon, mullite, clay and the like can be used.

As the aggregate in the refractory raw material, one whose particle size has been adjusted is used, and the amount used is 60 to 80% by weight. 60 used
If the content is less than 10% by weight, the powder becomes rich in fineness in terms of particle size composition. Therefore, at the time of construction, the fluidity is inferior, and the filling property is reduced, so that a densely packed construction cannot be obtained. On the other hand, if the amount is more than 80% by weight, the composition becomes too coarse in terms of particle size composition, and a densely packed construction cannot be expected.

It is appropriate to use 20 to 40% by weight of the refractory fine powder having a particle diameter of 74 μm or less. If it is less than this, the fluidity during construction will be impaired even if it is too large. There is also an adverse effect on the fillability of the construction.

〔Example〕

 Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.

Table 2 shows Examples and Comparative Examples, and FIG. 1 shows a comparison of curing properties between Examples and Comparative Examples. As is apparent from Table 2, Examples 1 to 4 in which the coding process of the present invention was performed were also Comparative Examples 1 in which the coding process was not performed, and Comparative Examples 2 and 3 in which the process conditions were out of the range. However, there is no significant difference in fluidity and strength index, and the treatment of the present invention does not cause deterioration of the product in this aspect. However, it can be seen from FIG. 1 that there is a temporal change in Comparative Examples 1 to 3, whereas there is almost no temporal change in Examples 1 to 4. Therefore, it can be seen that the amorphous refractory according to the present invention has little deterioration over time in quality and can maintain high quality for a long period of time. Further, the above-mentioned examples are used in various furnaces and molten metal containers of steel works, but the trouble due to the deterioration of the quality with time has disappeared.

[Effects of the Invention] As described above, the present invention can prevent the sodium phosphate from absorbing moisture by using sodium phosphate coated with hydrophobic silica ultrafine powder, and the quality of the sodium phosphate over a long period of time. An amorphous refractory capable of preventing deterioration was obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the change over time of the curing characteristics, FIG. 2 is a drawing substitute photograph showing the particle structure of the sodium phosphate according to the present invention,
FIG. 3 is a photograph substituted for a drawing showing a particle structure of sodium phosphate to which the present invention is not applied.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshiro Tani 1576, Higashi-oki, Aki-shi, Ako City, Hyogo Prefecture 2 Kawasaki Reactor Co., Ltd. (56) References 58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 35/66

Claims (1)

(57) [Claims] 1. A refractory raw material whose particle size has been adjusted, one or more alumina cements and ultrafine hydrophobic silica powder as a binder are stirred by a mixer having a stirring blade having a peripheral speed of 100 m / min or more for 5 minutes or more. An amorphous refractory to which one or more kinds of sodium phosphates are added, the amount of said hydrophobic silica ultrafine powder being 0.5 to 6% by weight of said sodium phosphate. Irregular refractories.