JPH08319152A - Alumina-magnesia-carbon regenerated refractory brick - Google Patents

Abstract

PURPOSE: To obtain an Al2 O3 -MgO-C regenerated refractory brick capable of effectively reutilizing used Al2 O3 -MgO-C refractory bricks massively generated from the ladles of a steel mill, thereby reducing the cost for treating or throwing away the used bricks, and effectively utilizing the resource. CONSTITUTION: This Al2 O3 -MgO-C regenerated refractory brick is produced by removing deteriorated layers on the operated surface sides of waste Al2 O3 -MgO-C bricks used as the lined refractory bricks of a ladle, grinding the left parts, mixing the waste brick ground product with a raw material for new Al2 O3 -MgO-C bricks in such an amount that the amount of the waste brick ground product is <=30% based on the whole amount of the mixture, and subsequently molding the mixture.

Description

Detailed Description of the Invention

[0001]

This invention relates to Al ₂ O ₃ --MgO--C.
More specifically, the present invention relates to Al ₂ O ₃ —MgO—C-based recycled refractory bricks made by recycling used refractory bricks.

[0002]

2. Description of the Related Art In steelmaking factories, MgO-C type refractory bricks, MgO type refractory bricks, M, etc. are used as lining refractory materials for electric furnaces, AOD furnaces, ladles, etc.
gO-Cr ₂ O ₃ refractory bricks, various refractory bricks such as Al ₂ O ₃ -MgO-C based refractory bricks are used.

After these refractory bricks are used for a certain period of time, they are replaced with new refractory bricks, and a large amount of used refractory bricks (waste bricks) is generated at that time. The amount generated is large (for example, 10,000 tons) every year. Most of the used waste bricks that have been generated have been disposed of by burying them in the factory's disposal site, but there is a limit to the disposal in the disposal site. There is a problem that the disposal cost will increase if it is disposed of in the field. Moreover, even if dumping into a public dump, there is a problem that the public dump itself is limited.

Therefore, it is desirable in terms of cost and effective utilization of resources if the waste bricks from the steelmaking plant can be reused. In particular, it is more desirable if the waste bricks can be recycled as the refractory bricks, which is the original purpose, because the price of the refractory bricks is high.

[0005]

The present invention focuses on used refractory bricks generated from a ladle among the refractory bricks,
It was made for the purpose of effective use. Thus, the invention of the present application is to grind the remaining part of the Al ₂ O ₃ —MgO—C type waste brick used as the lining refractory brick of the ladle to remove the deteriorated layer on the operating surface side, and crush the waste brick. the pulverized product against Al ₂ O ₃ -MgO-C type new bricks material, the ratio of total mixed material is mixed in a ratio equal to or less than 30%, formed by molding Al ₂ O ₃ -MgO-C type Reclaimed refractory bricks are the gist (Claim 1).

According to another aspect of the present invention, there is provided a recycled refractory brick in which the C content in the used waste brick is C%.
Is removed by 2% or more lower than C% in the original brick as the altered layer, and the remaining portion is used for recycled refractory bricks (claim 2).

The recycled refractory brick of still another invention of the present application is
In Claim 1 or 2, the said used waste brick is what was used for parts other than the slag line of the said ladle, and the said recycled refractory brick is for lining the part other than the slag line of this ladle. It is a thing (Claim 3).

[0008]

As described above, the present invention recycles used refractory bricks generated from a ladle. Impurities such as adhered slag are attached to the used refractory bricks generated from this ladle, and the operating surface side in contact with the hot water is in a state of being deteriorated by heat or the like. Therefore, used waste bricks cannot be used as they are as raw materials for refractory materials.

However, when the present inventor investigated the components of the remaining portion after the deteriorated layer on the operating surface side was removed, it was found that the amount of some slag components, specifically, SiO ₂ , Fe ₂ O ₃ , CaO, etc., increased. Although it is recognized, as a whole, it is not much different from the composition of the original brick before use, that is, the new brick, and if the remaining part is used there and if the usage amount (addition amount) is limited, this It was thought that it could be utilized for recycled refractory bricks.

Under this focus, a crushed product of used waste bricks and a raw material for new bricks are mixed and molded to produce a recycled refractory brick, and at this time, the mixed amount of the crushed product of used waste bricks is varied. When the characteristics of the obtained recycled refractory bricks were investigated by changing it, high-grade refractory bricks that could actually be used as refractory bricks were actually used if the mixture amount of crushed waste bricks was reduced to 30% or less. It turned out to be obtained.

According to the present invention, it is possible to effectively use limited resources, and to reduce the cost required for disposal and disposal by reducing the amount of disposal at the disposal site or disposal site and the amount of disposal. The cost required for expensive refractory bricks can be saved. In the present invention, the more preferable range of addition amount of the used waste brick crushed product is 20% or less.

According to the second aspect of the present invention, a portion of the used waste brick having a C content lower than that of the original brick by 2% or more is removed as an altered layer, and the remaining portion is used for recycled refractory brick. According to the present invention, it is possible to prevent the quality of recycled fire-resistant bricks from being significantly deteriorated by the addition of the used waste brick crushed product, and it is possible to maintain high corrosion resistance of the recycled fire-resistant bricks.

The recycled refractory bricks of claims 1 and 2 can be sufficiently used as a refractory brick for a ladle. The use conditions of refractory bricks for ladle are very severe, and if the content of impurities is high, the corrosion resistance is significantly reduced. Therefore, in the case of the recycled refractory bricks of claims 1 and 2 in which the amount of used waste bricks is suppressed to 30% or less, as the refractory brick for ladle, more specifically, in the portion other than the slag line It can be fully used as a fireproof brick. In other words, the recycled refractory bricks of claims 1 and 2 are highly effective when used as a refractory brick for a ladle that is used under severe conditions and requires high quality.

[0014]

EXAMPLES Examples of the present invention will be described in detail below. Used Al ₂ generated from parts other than slag line of ladle
O ₃ to remove slag and deteriorated layer adhering to the working surface from -MgO-C refractory bricks (recovered waste bricks), and analyzed chemical composition of the remaining portion. The results are shown in Table 1 in comparison with that of the raw brick in the unused state.

[0015]

[Table 1]

As shown in Table 1, the chemical composition of the recovered waste brick is Si, which is a slag component compared to the original brick.
Although a slight increase in O ₂ , Fe ₂ O ₃ , and CaO is recognized, it is close to that of the original brick as a whole. In addition, here, the portion where the C content on the operating surface side was lower than the original brick by 2% or more was removed as an altered layer. However, as refractory bricks for ladle, three kinds of C% content of 10%, 8% content and 5% content are used, and the amount of C in the recovered waste bricks in the above Table 1 is three kinds. It is the C content in the state where the collected waste bricks are mixed.

As described above, if the content of impurities in the recovered waste bricks increases, the corrosion resistance, that is, the durable life, decreases sharply. Therefore, in order to investigate the possible addition amount of crushed waste bricks, the corrosion resistance was evaluated by changing the mixing ratio with respect to the new brick raw material. The results are shown in Figure 1. Here, the corrosion resistance is represented as a melt loss index.

From the results shown in FIG. 1, if the amount of the recovered crushed waste bricks added exceeds 30%, the corrosion resistance is sharply reduced. In other words, if the amount added is kept below 30%, good corrosion resistance is maintained. I understand that. Further, it can be seen from FIG. 1 that the amount of the recovered waste brick pulverized material added is preferably 20% or less. In addition, in FIG. 1, the melting loss index is represented by a relative numerical value when the degree of melting loss of the original brick is 100.

Next, FIG. 2 illustrates the relationship between the mixing ratio of the recovered waste brick crushed product and the residual expansion ratio and illustrates this. Here, the residual expansion rate is a value in which the refractory brick is heated to a predetermined high temperature and then cooled, and the residual expansion amount (strain amount) is expressed in percentage. This residual expansion coefficient has the following meaning. When a refractory brick is used as a lining for a ladle, if the residual expansion rate due to heating and cooling is small, cracks will occur between the joint and the joint. Therefore, it is desirable that the residual expansion coefficient is above a certain level.

Then, in order to investigate this, when the relationship between the mixing ratio of the recovered waste brick crushed product and the residual expansion rate was obtained,
It was found that when the mixing ratio was 30% or less, the residual expansion coefficient did not decrease so much, and when the mixing ratio exceeded 30%, the residual expansion coefficient decreased significantly.

Therefore, also from the viewpoint of the residual expansion coefficient, it is understood that the mixing ratio of the recovered waste brick crushed product is preferably 30% or less. It is estimated that the residual expansion rate decreases as the mixing ratio of the collected waste brick crushed product increases because the recovered waste brick crushed product has already undergone thermal history and the change due to heat has ended. To be done.

When an actual furnace test of recycled refractory bricks was carried out based on the above results, those with a mixing ratio of recovered waste bricks crushed to 30% or less were used for both metal lines and freeboards. It was confirmed that the device could withstand practical use even when there was a problem.

Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be implemented in variously modified modes without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a waste brick mixing ratio and a melt loss index obtained in an example of the present invention.

FIG. 2 is a diagram showing a relationship between a waste brick mixing ratio and a residual expansion ratio, which are also obtained in the example of the present invention.

Claims (3)

[Claims] 1. A crushed residual brick of an Al ₂ O ₃ —MgO—C waste brick used as a lining refractory brick of a ladle, from which a residual layer after removal of an altered layer on the working surface side is pulverized, against al ₂ O ₃ -MgO-C type new brick material,
An Al ₂ O ₃ —MgO—C-based recycled refractory brick obtained by mixing and molding the mixture at a ratio of 30% or less in the whole mixed material. 2. The C content in the used waste brick according to claim 1, which is 2% more than the C% in the original brick.
The Al ₂ O ₃ —MgO—C-based regenerated refractory brick, wherein the lowered portion is removed as the altered layer and the remaining portion is used for regenerated refractory brick. 3. The used waste brick according to claim 1 or 2, wherein the used waste brick is used in a portion other than the slag line of the ladle, and the recycled refractory brick is a portion other than the slag line of the ladle. Al ₂ O ₃ —MgO—C-based regenerated refractory brick, which is used as a lining material.