JPS63186817A - Permeable refractory - Google Patents

Abstract

PURPOSE:To easily and accurately detect usable remaining part by color change at center part and to improve safety of prevention of molten steel leakage, etc., by forming a cavity part on working side face of a refractory having large permeability. CONSTITUTION:The cavity part 6 is formed on the working side (molten steel side at the time of setting in ladle bottom) of the refractory 5(B) having large permeability in gas introducing part. The permeability in the permeable refractory 5(B) at gas introducing side is larger than the permeability in a permeable refractory 4(A) at the working side of the cavity part 6 and it is desirable that difference between these permeabilities is made to >=0.05cm<3>/sec.cmH2O. Thickness of the cavity part 6 is made to about 0.3-8mm. By this double construction, in case the refractory 4(A) is damaged caused by red heat, the center part 8 appears to become blackish. By observing this from out of the ladle, the detection of remaining part of the refractory is easily and accurately confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a breathable refractory, and more particularly to a breathable refractory commonly referred to as a porous plug whose use limit can be detected.

[Prior Art] In order to improve the quality of steel, it has been widely adopted to inject gas such as argon gas into molten steel through a breathable refractory to stir, decarburize, and remove nonmetallic inclusions.

The breathable refractory for this purpose is generally placed at the bottom of the pot, so it is very important to judge the amount of wear and tear, that is, to detect the usage limit.If used beyond the limit, hot water may leak. This may lead to serious accidents such as

For this reason, various considerations have been made to determine critical dimensions, but there are advantages and disadvantages, and the reality is that they must be used with excessive consideration given to safety in terms of accuracy, ease, etc.

For example, (1) the shape of the gas blowing part changes as the number of times it is used increases (2) reading temperature changes have been adopted or proposed.

[Problems to be solved by the invention] The above-mentioned conventional method is reasonably effective, but (1)
) refers to the use of larger than allowable dimensions depending on the operating time or operating conditions, and (2) refers to the use of several temperature sensors (
The cost of embedding a thermocouple (thermo couple) is high, and the necessary equipment is required, which is unsatisfactory, and improvements have been desired.

The present invention was discovered as a result of various studies from these viewpoints.

[Means for Solving the Problems] The present invention is characterized in that the gas introduction part is made of a porous refractory having a higher permeability than at least the surrounding area, and a void is formed on the operating side of the refractory having a high permeability. It is a breathable refractory made of

The breathable refractory of the present invention will be explained below with reference to the drawings. Figure 1 shows a typical example, (1) is a sleeve brick, (2) is an iron shell, (3) is a gas introduction pipe,
(4) Porous breathable refractory A, (5) porous breathable refractory B, and (6) voids.

Here, the refractories of the present invention are basically breathable refractories A and B.
and the permeability of the refractory B located in the gas introduction part is at least greater than that of the surrounding refractory A, and a void is formed on the working side of the refractory B at the joint surface between both refractories. The refractory of the present invention is thus made of two types of refractories with different air permeability, with voids formed between them, and the material of the air permeable refractory is alumina, mullite Commonly used materials such as quality and chromia can be used as they are.

In the present invention, a preferred refractory is a refractory with a high permeability placed in the center lower part as a gas introduction part, and a refractory with a lower permeability formed in the upper part (operating side) and sides to form a gap. It is something that is made by being molded into the body.

To explain the air permeability here, it is necessary that the two types of refractories have at least a difference, preferably cm2
0 as a value measured at room temperature in /sec-cmH2O
．． 05 or more, that is, the air permeability of refractory B in the gas introduction section should be 1.05 times or more than that of refractory A, and generally 0.05 to 1.05. O1 is preferably 0. IN
It should be about 0.5.

Note that the air permeability of refractories A and H is generally 0.5 to 0.5.
It is preferable that the concentration is about 2.0 cm2/sac-cmH2O.

In the present invention, the void is at least on the working side of the refractory B of the gas introduction part where the air permeability is large (the hot water surface side when installed at the bottom of the pot)
The basic form is 1 as shown in Figure 1.
The important thing is to ventilate the entire surface of the operating side of the refractory.
As shown in FIG. 3, it may of course be formed in a part thereof.

It is desirable that the effective area of the void is as large as possible, but even in the embodiment shown in FIG. 3, it is usually desirable to keep it approximately 7c+o2 or more.

In addition, the thickness d of the cavity is preferably larger from the viewpoint of the desired detection effect, but if it is too large, the durability will decrease, so there is a limit, and the preferable range is 0.3 to 0.
8 mm, preferably 0.5 to 5 sm.

[Function] The usage limit detection function in the present invention is as described below.

Taking steelmaking as an example, a permeable refractory such as a porous plug is usually placed at the bottom of a refining vessel called a ladle. 1
After the refining process is completed, the inside of the furnace is generally observed, and the porous plugs are observed to be red hot. However, due to the double structure shown in the present invention, when the refractory material A wears out, the central part becomes dark as shown in Fig. 2 at a certain point, and as a result, the remaining thickness is small. It is possible to detect this and know the limits of use. The reason for this is that the refractory material B having a higher permeability than the surroundings is provided in the gas introduction section, so that the introduced gas is mainly supplied to the refractory material A through the refractory material B. Therefore, refractory B is refractory A
As the remaining thickness of the refractory material A decreases, the temperature of the upper part of the refractory material B decreases faster than the surrounding area, making it appear darker than the surrounding area. In order to maximize this effect, it is necessary to provide a gap between the refractories A and B. Furthermore, the fact that the permeability of refractory B is greater than that of refractory A contributes to enhancing the detection effect.

[Example] An alumina refractory as shown in FIG. 1 was produced, and Table 1 shows the results obtained using an 80-ton LF pot.

Table 1 As shown, sample 1 had no voids, and even though the residual thickness was small, the darkening at the center was not very obvious. In No. 2, voids were provided using refractories with the same air permeability, but the darkening in the center was not clear.

On the other hand, in Samples 3 and 4, which are products of the present invention, it was confirmed that the dark spots in the center were clearly visible and the residual detection could be done extremely easily and accurately. It was also confirmed that Sample 4 did not necessarily have sufficient durability.

[Effects of the Invention] As described above, the present invention, as a breathable refractory, allows for easy and accurate detection of remaining refractories by color change in the center when approaching the usable remaining size, and is highly safe in terms of preventing steel leakage. , and those with identified voids have sufficient durability and are of great practical value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a basic structural example of the present invention. Fig. 2 is an explanatory diagram showing how the refractory of the present invention is used, and Figs. 3(a) and 3(b) are cross-sectional views showing application examples of the refractory of the present invention. is iron skin, 3 is pipe, 4 is breathable refractory A, 5 is breathable refractory B, 6
7 shows the air gap, 7 shows the outside observation surface of the air-permeable refractory material A, and 8 shows the blackened part in the center. 81 Illustration 3

Claims (4)

[Claims] (1) Air permeability, characterized in that the gas introduction part is made of a porous refractory having a higher permeability than at least the surrounding area, and a void is formed on the operating side of the refractory having a high permeability. refractory (2) The refractory according to claim 1, in which the permeability of the refractory in the gas introduction part is higher than the permeability of the refractory on the working side of the void part. (3) Difference in air permeability is 0.05cm^2/sec・cmH
The refractory according to claim 1 or 2, which is _2O or more (4) Any one of claims 1 to 3, wherein the thickness of the void formed at the joint surface of two types of refractories with different air permeability is 0.3 to 8 m/m. Refractories listed