JP3347164B2 - Irregular refractories - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous refractory, and more particularly to an amorphous refractory containing alumina cement and sodium phosphate as a binder.

[0002]

2. Description of the Related Art In recent years, when refractory linings are applied to various furnaces, amorphous refractories (castable refractories) using hydraulic alumina cement and sodium phosphate as binders are widely used. However, amorphous refractories using alumina cement and sodium phosphate as binders have a hardening time that fluctuates due to temperature changes, and the hardening time becomes longer under low temperature conditions such as winter, and in summer or hot Under high temperature conditions, as in the case of construction, the curing time is short.

[0003] Therefore, when the curing time is too short to hinder the work, the curing time is reduced by using a curing retarder.
That is, the pot life is controlled.

[0004] In the above-mentioned irregular shaped refractories, a burst explosive such as metallic aluminum is added in order to prevent explosion in a drying step after construction.

[0005] As described above, in the conventional amorphous refractories, a curing retarding additive (curing retardant) is used in order to secure the pot life by delaying curing and prevent explosion.
And at least two of explosion-prevention additives (explosion-prevention agents)
It is common to use (in combination) more than one type of additive.

[0006]

However, in the above-mentioned conventional amorphous refractory, since two or more kinds of additives are used, the material design for determining the kind and the amount of addition becomes complicated. In addition to the problem, there is a problem that the compounding operation in the manufacturing process becomes complicated.

[0007] The present invention solves the above-mentioned problems, and it is possible to easily and surely delay the curing simply by adding a single additive without using a plurality of additives, and to perform a drying step. It is an object of the present invention to provide an irregular-shaped refractory capable of preventing explosion of a construction body in a building.

[0008]

In order to achieve the above object, the inventor has conducted various experimental studies and found that sodium bicarbonate has a function of delaying hardening and suppressing explosion in a drying process after construction. Knowing that, further experiments,
The present inventors have studied and completed the present invention.

That is, the amorphous refractory of the present invention is obtained by adding 0.01 to 0.5% by weight of sodium bicarbonate to an amorphous refractory containing alumina cement and sodium phosphate as a binder. It is characterized by the following.

[0010]

In the amorphous refractory of the present invention, sodium bicarbonate reacts with Ca ²⁺ eluted from alumina cement as shown in the following formula (1) to exhibit a function of delaying hardening. 2NaHCO ₃ + Ca ²⁺ → CaCO ₃ + H ₂ O + CO ₂ ↑ + 2Na ²⁺ (1)

At this time, CO ₂ gas is generated, and fine holes are formed in the construction body, thereby preventing explosion. Incidentally, sodium bicarbonate is obtained by the above formula (1)
At a temperature of 65 ° C. or more without depending on the reaction
It decomposes as shown in (2) to form fine holes in the construction body and exerts the function of preventing explosion. 2NaHCO ₃ → Na ₂ CO ₃ + H ₂ O + CO ₂ … (2)

[0012] In the amorphous refractory of the present invention,
Addition amount of sodium bicarbonate is 0.01-0.5% by weight
It is preferable that the addition amount of sodium bicarbonate is less than 0.01% by weight, no significant addition effect is observed, and the addition amount exceeds 0.5% by weight. Remarkable improvement of the addition effect is not recognized even if
If the added amount is further increased, problems such as a decrease in mechanical strength occur.

[0013]

Hereinafter, the features of the present invention will be described in more detail with reference to examples of the present invention and comparative examples.

[0014] Sintered alumina (coarse grain, intermediate grain, fine powder), alumina cement and sodium phosphate are blended in the proportions shown in Table 1, and sodium bicarbonate is further added thereto in the proportions shown in Table 1. An amorphous refractory (Examples 1 to 5 in Table 1) was prepared by the addition.

[0015] Then, for these irregular shaped refractories,
The curing time was measured, and the state of explosion in the drying process was examined. Table 1 shows the results.

[0016]

[Table 1]

The "curing time" in Table 1 was measured by kneading each amorphous refractory with water, casting the kneaded material in a constant temperature bath at 70 ° C., and then curing the kneaded material. Things.

Further, the "state of occurrence of explosion" in Table 1
Is to apply the cured body at a rate of 100 ° C./hr to 800 ° C.
It is an observation of the presence and extent of the occurrence of explosion when drying by heating to a maximum temperature.

For comparison, an amorphous refractory without the addition of sodium bicarbonate (Comparative Example) was prepared, and its characteristics were examined in the same manner as in the amorphous refractory of the above example.
The results are shown in Table 1.

According to Table 1, the amorphous refractories of Examples 1 to 5 (amount of sodium bicarbonate added: 0.01 to 0.5% by weight)
Shows that the curing time was longer than that of the amorphous refractory of Comparative Example to which sodium bicarbonate was not added, and that sodium bicarbonate exhibited a function of delaying the curing.

Regarding the state of occurrence of explosions, many explosions were observed for the amorphous refractory of Comparative Example to which sodium bicarbonate was not added.
Regarding the amorphous refractory of No. 5, only the amorphous refractory of Example 1 in which the amount of sodium bicarbonate added was 0.01% by weight showed very slight explosion. Examples 2 to 5 (addition amount of sodium bicarbonate: 0.
(0.5 to 0.5% by weight), no explosion was observed at all.

In the amorphous refractory of the present invention, there are no particular restrictions on the type of refractory aggregate, the proportion of alumina cement or sodium phosphate added to the refractory aggregate, etc., and within the scope of the invention. Various applications,
Deformations can be made.

[0023]

As described above, the amorphous refractory of the present invention is an amorphous refractory containing alumina cement and sodium phosphate as a binder, wherein sodium bicarbonate is applied in an amount of 0.01 to 0.2 mm. Since 5% by weight is added, it is necessary to separately add a plurality of additives (curing retardant and explosion-preventing agent) as in the related art, thereby complicating material design and reducing workability. In addition, simply adding a single additive, easily and surely delays hardening during hot work, etc., and secures the necessary pot life, and also prevents the work from exploding in the drying process. Can be.

Claims (1)

(57) [Claims] 1. An amorphous refractory containing alumina cement and sodium phosphate as a binder, characterized in that 0.01 to 0.5% by weight of sodium bicarbonate is added on the outside. .