JP2000119061A - Unfired high-alumina brick for melting high alloy metals. - Google Patents

Abstract

(57) [Summary] An unfired high-alumina brick for melting a high alloy metal which is advantageous in that the phosphate binder is abolished and the amount of erosion is reduced while maintaining the characteristics of unfired and high alumina. provide. An unsintered high-alumina brick includes an alumina-based aggregate, an alumina-based fine powder part, and a sodium silicate-based binder that binds the alumina-based aggregate, and the alumina-based fine powder part is 100% by weight of the alumina-based fine powder part. It is composed of a material containing alumina fine powder particles occupying 70% by weight or more and silica fine powder particles occupying less than 30% by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unfired high-alumina brick for melting high alloy metals used for melting high alloy metals such as stainless steel and heat resistant steel.

[0002]

2. Description of the Related Art Unfired high alumina bricks have been used. Since it is not fired, it is advantageous not only in cost but also in spalling resistance. The unfired high-alumina brick is composed of an alumina-based aggregate, an alumina-based fine powder portion, and a binder that connects these. In this case, a synthetic alumina raw material and a natural alumina raw material are used as aggregates, and synthetic alumina fine powder and alumina
Silica-based fine powder and silica-based fine powder are used, and further, a phosphoric acid-based binder is used as a binder. A mixed material obtained by mixing these is kneaded, and the kneaded material is formed into a molded body. Dry at about ℃ or less,
Unfired high alumina bricks have been produced. The alumina-based fine powder and the phosphoric-acid-based binder can exhibit strong bonding strength due to the formation of the aluminum-phosphate-based compound, and thus are used in most unfired high-alumina bricks.

[0003]

The unfired high-alumina brick used for melting high-alloy steels such as stainless steel, heat-resistant steel, and special steel has been widely used in recent years. As a result, the cases where phosphate binders cannot be used are increasing. In view of this, there has been proposed a method of forming a fired high alumina into a ceramic bond type, or a method of substituting a non-fired brick formed of a material other than high alumina.

[0004] However, these measures have the disadvantage that the characteristics of the brick are greatly changed, which considerably affects the operation of melting high alloy steel such as stainless steel and increases the cost. The present invention has been made in view of the above-described circumstances, and maintains the characteristics of unfired high alumina, abolishes a phosphate binder, and further has the advantage of reducing the amount of erosion. It is an object to provide an alumina brick.

[0005]

Means for Solving the Problems The present inventor has intensively developed unfired high alumina bricks for melting high alloy metals. The phosphate binder was abolished, and unfired high-alumina bricks mainly composed of alumina-based aggregates, alumina-based fine powder parts, and sodium silicate-based binders that bind them together were adopted. Is 100% by weight, a material containing alumina fine particles occupying 70% by weight or more and silica fine particles occupying less than 30% by weight constitutes an alumina-based fine powder portion, thereby melting a high alloy metal. The present inventor has found out that it is advantageous for reducing the amount of erosion of the brick at the time, and confirmed it by a test, thereby completing the present invention.

The unsintered high-alumina brick for melting a high-alloy metal according to the present invention comprises an alumina-based aggregate, an alumina-based fine powder portion, and a sodium silicate-based binder that binds the alumina-based aggregate and the alumina-based fine powder portion. When the alumina-based fine powder portion is 100% by weight, the material is characterized by being composed of a material containing alumina fine powder particles occupying 70% by weight or more and silica fine powder particles occupying less than 30% by weight.

The unfired high alumina brick according to the present invention can reduce the amount of erosion and contribute to prolonging the life.

[0008]

DETAILED DESCRIPTION OF THE INVENTION According to the non-sintered high-alumina brick of the present invention, alumina-based aggregates generally have a coarse particle size of 5 to 1 mm and a particle size of 1 to 0.5 mm. Medium grain,
It can be composed mainly of fine particles having a particle size of 0.5 to 0.1 mm. The alumina-based fine powder portion can be formed mainly of fine powder particles having a particle size of 105 μm or less. The sodium silicate-based binder can be added, for example, in an amount of about 1 to 6% by weight or about 2 to 3% by weight.

According to the non-sintered high-alumina brick of the present invention, the alumina-based fine powder part is one of the alumina-based fine powder parts.
When the content is 00% by weight, it is composed of a material containing 70% by weight or more of alumina fine powder particles and less than 30% by weight of silica fine powder particles. 1 alumina fine powder
When the weight is 00% by weight, the alumina fine powder particles are, for example, 74
To 98% by weight, and the silica fine powder particles are, for example, 2 to 26%.
Weight percent.

According to a preferred embodiment of the non-sintered high alumina brick for melting a high alloy metal according to the present invention, the fine silica particles constituting the fine alumina particles have an average particle diameter of 10 μm.
m or less silica fine powder particles can be mainly used. Also, alumina fine powder particles constituting the alumina fine powder portion,
Alumina fine particles having an average particle size of 40 μm or less can be mainly used.

According to the unfired high-alumina brick of the present invention, since the firing is not performed before use, the particle size and composition of the particles can be determined. However, if the brick is heated to the sintering temperature by touching the high-temperature molten high-alloy metal as it is used, it is considered that the sintering of that portion proceeds. In producing the unsintered high-alumina brick according to the present invention, a mixed material is obtained by mixing an alumina-based aggregate, an alumina-based fine powder, and a sodium silicate-based binder that binds them, and a kneaded material is obtained by kneading the mixed material. A step of forming a kneaded material to obtain a molded body and a step of drying the molded body at 500 ° C. or lower can be employed. For molding, a friction press or a hydrostatic molding method (CIP) can be employed.

As a storage pan for storing a high alloy metal melt,
Some are provided with an iron shell and a lining layer lined with the iron shell.
The unsintered high-alumina brick according to the present invention has good erosion resistance and can be used on the lower side of the lining layer that comes into contact with the high alloy metal melt. In this case, the operating temperature of the brick generally rises to 1700 to 1800 ° C. Examples of high alloy metals include stainless steel (austenitic, ferritic, martensitic), heat-resistant steel, magnet steel, high-alloy tool steel, and special steel.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
The non-fired high alumina brick according to the present embodiment is used as a lining refractory layer when a high alloy metal such as stainless steel or heat resistant steel is melted. The non-sintered high alumina brick is composed of an alumina-based aggregate, an alumina-based fine powder portion loaded between the alumina-based aggregates, and a sodium silicate binder connecting these. The composition is shown in Table 1.

[0014]

[Table 1] According to this embodiment, (A) to (E) serve as aggregates for bricks. The alumina fine powder portion disposed between the aggregates has alumina fine powder particles (F) having a particle size of 44 μm or less and silica fine powder particles (G) having a particle size of 10 μm or less.
It is composed of

As can be seen from Table 1, alumina fines account for 16% by weight and silica fines account for 4% by weight in the entire brick matrix. Therefore, the alumina-based fine powder portion accounts for 20% by weight (= 16% by weight + 4% by weight) in the entire brick matrix. Therefore, assuming that the alumina fine powder portion is 100% by weight, the alumina fine powder particles are 80% of the alumina fine powder portion.
Wt%, and the fine syringine particles account for 20 wt%.

In producing the unsintered high alumina brick according to the present embodiment, a step of mixing the above-mentioned raw material and sodium silicate binder to obtain a mixed material is performed. Next, the mixed material is charged into a molding cavity of a mold and molded by a friction press to obtain a brick-shaped molded body. Next, a step of drying the molded body at 500 ° C. or lower in an oxidizing atmosphere is performed. This forms an unfired high alumina brick.

(Test Example) Based on the above-described examples, unfired high alumina-based bricks in which the ratio of the silica fine powder particles in the alumina fine powder portion was variously changed were produced. In this case, aggregate (coarse, medium, fine) in brick
Is 80% by weight, and the alumina-based fine powder portion is 20% by weight.

Using a high-frequency induction furnace (for 50 kg) lined with the unfired brick produced as described above as a refractory layer, slag (basicity c / s = 2.0) is generated and floated on the liquid surface of molten steel. While molten steel (steel type: stainless steel SU
S) is heated and maintained at 1700 ° C. for a predetermined time (8 hours),
A test was performed to measure the amount of erosion of the brick. The test results are shown in FIG. The horizontal axis of FIG. 1 shows the ratio of the silica fine powder particles in the alumina fine powder portion. The vertical axis in FIG. 1 indicates the erosion amount ratio number. The erosion amount increases as going upward, and the erosion amount decreases as going downward. The vertical axis represents the relative amount of the erosion amount ratio as 100 when the ratio of the silica fine powder particles in the alumina fine powder portion is 0% by weight.

As shown in FIG. 1, as the proportion of the silica fine powder particles in the alumina fine powder portion increases from 0% by weight, the erosion amount ratio gradually decreases. If the proportion occupied by the silica fine powder particles is less than 30% by weight, the erosion amount ratio is good, and the erosion of the brick is small. In particular, when the silica fine powder particles in the alumina fine powder portion are 10 to 25% by weight, the erosion amount ratio is good and the erosion of the brick is small.

However, the silica fine powder particles are 35% by weight.
Approximately, the erosion ratio increases, and erosion tends to increase rapidly. Further, when the proportion of the silica fine powder particles exceeds 70% by weight, the erosion amount ratio number becomes 190
, And the amount of erosion increases considerably. Therefore, the proportion of the silica fine powder particles in the alumina fine powder portion is 30%.
It can be said that it is preferable that the amount is less than the weight%.

(Application Example) FIG. 2 shows an application example. This application example is applied to a V alloy housing a high alloy metal melt such as stainless steel.
This is a case where it is adopted as a lining refractory layer used for the storage pan 2 which is an OD pan. VOD pans are used to refine stainless steel in a vacuum chamber. The storage pan 2 includes a container-shaped iron shell 20 and a lining refractory layer 22 lined with the iron shell 20.

The above-mentioned unfired high alumina brick 25
(Areas indicated by hatching) are formed on the inner surface of the lower part of the side wall 20a of the iron shell 20 and the inner surface of the bottom floor 20c. Further, a magnesia-carbon-based brick 27 is constructed on the inner surface of the upper portion of the side wall 20a of the iron shell 20 as in the conventional case. Thereby, the lining refractory layer 22 is formed. The unfired high-alumina brick 25 comes in contact with high-temperature, high-alloy metal molten steel or slag generated and suspended in molten steel.
Since the temperature rises to about 700 to 1800 ° C., erosion resistance at high temperatures is particularly required.

The life of the lining refractory layer was examined under the same molten steel operating conditions as in the past. When the unfired high-alumina brick using the conventional phosphoric acid binder was used as the lining refractory layer, Although the life was about 10 ch, when the non-fired high alumina brick 25 according to the present example was adopted, it was about 12 ch, and it was confirmed that the life was prolonged. Further, the unsintered high-alumina brick 25 according to the present embodiment is a non-phosphorous brick and does not use a phosphate binder that affects molten steel. Suitable for production.

[0024]

According to the unfired high alumina brick of the present invention, since no phosphate binder is employed, it is suitable for melting high-alloy metals such as stainless steel and heat-resistant steel, which do not like the inclusion of phosphorus. Further, the unfired high alumina brick according to the present invention is advantageous in reducing the amount of erosion and can contribute to extending the life of the lining refractory layer.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the proportion occupied by silica fine powder particles in an alumina-based fine powder portion and the amount of erosion.

FIG. 2 is a cross-sectional view illustrating an application pot, in which an unsintered high-alumina brick according to the embodiment is applied to a lining refractory layer.

[Explanation of symbols]

In the figure, 2 is a storage pan, 20 is an iron skin, 22 is a lining refractory layer,
Reference numeral 25 denotes an unfired high alumina brick.

Claims (4)

[Claims] An alumina-based aggregate, an alumina-based fine powder part,
A sodium silicate-based binder that binds them, wherein the alumina-based fine powder portion is
An unfired high alumina for melting a high alloy metal, comprising a material containing alumina fine powder particles occupying 70% by weight or more and silica fine powder particles occupying less than 30% by weight when 0% by weight. Quality brick. 2. The fine silica particles have an average particle size of 10 μm.
The unfired high-alumina brick for melting a high alloy metal according to claim 1, wherein the high-alumina brick is mainly composed of silica fine powder particles having a particle size of m or less. 3. The alumina fine particles have an average particle size of 40.
The unsintered high-alumina brick for high alloy metal melting according to claim 1, characterized in that the non-fired high-alumina brick is mainly composed of alumina fine powder particles having a particle size of not more than μm. 4. A storage pot for storing a high alloy metal melt having a steel shell and a lining layer lined with the steel shell, wherein a lower portion of the lining layer in contact with the high alloy metal melt is provided. The unfired high alumina brick for high alloy metal melting according to claim 1, which is disposed.