KR20030052343A - Composition of basic castables with self flowability - Google Patents

Abstract

PURPOSE: A basic amorphous refractory composition is provided, which has a self-fluidity, shows excellent erosion resistance and spalling resistance and can be used as the dam block for a tundish, the slag line part of a ladle or the precipitation pipe of RH equipment. CONSTITUTION: The basic amorphous refractory composition comprises 24-34 wt% of spinel clinker powder with a size of 0.074 mm or less; 5-10 wt% of calcined alumina fine powder; 2-3 wt% of alumina cement; 1-3.0 wt% of silica flower; the balance of magnesia clinker with a size of 1-5 mm; and additional component comprising 0.1-0.4 wt% of sodium hexametaphosphate and 0.01-0.02 wt% of citric acid. Preferably the total amount of the spinel clinker powder, the calcined alumina fine powder, the alumina cement and the silica flower is 35-45 wt%, and the size of the components is 0.074 mm or less.

Description

Composition of basic castables with self flowability

The present invention relates to a high-resistance basic amorphous form refractory composition having self-flowability that can be used in a slag line portion of a ladle line, an iron making process facility, or a sedimentation pipe of an RH facility, and a tundish dam block of a performance factory facility. More specifically, the present invention relates to a high-resistance magnesia-spinel-like amorphous refractory composition which can simplify the construction than the existing vibration inflow construction material and has excellent corrosion resistance and spalling resistance.

Refractories for steel are increasingly used in the form of irregular refractory materials for the purpose of improving energy efficiency and energy saving. Among them, the use of irregular refractory materials for inflow and construction is very simple because of its advantages. Inflow construction prepares the mold in advance so that a wall of a certain thickness can be formed in a relatively simple facility such as ladle or tundish, and after the castable refractory is introduced into the mold, the castable is uniformly applied. It is a construction method to be filled. Since the inflow construction material is applied by applying strong vibration to the mold or inflow material, it is difficult to secure the homogeneity of the construction by separating the fine part and the aggregate part, and the difference of physical properties between the upper and lower parts of the wall or the wall surface and the central part occurs. There is a problem of lowering the life of the whole.

Therefore, in order to improve this, alumina castable or alumina-silica castable has been developed with an inflow material having self-flowability that can be inflowed only by the load of the material itself without vibrating by reinforcing the granularity of the inflow material. It is used and is known to have excellent performance. By the way, the technique which solved the problem of a basic inflow material is not known.

SUMMARY OF THE INVENTION The present invention provides a composition of a basic inflow material having excellent corrosion resistance against slag and excellent workability having self flowability with excellent hot strength.

1 is an example of an experimental apparatus for measuring the height of the step

* Description of the symbols for the main parts of the drawings *

1 .... U-shaped

2 ..... Influent

3 ..... step of entry and exit

Basic inflow material of the present invention for achieving the above object, 5-1mm size magnesia clinker 55-65% by weight, less than 0.074mm size spinel clinker powder 24-34% by weight, ultra finely divided alumina 5-10% by weight alumina 2-3 wt% of cement and 1-3.0 wt% of silica flower are used as the basic composition, and 0.1-0.4 wt% of hexametaphosphate and 0.01-0.02 wt% of citric acid are extrapolated to the basic composition.

Hereinafter, the present invention will be described in detail.

Magnesia clinker: 55-65 wt%

The purity of the magnesia clinker is preferably used in the content of magnesia (MgO) of 98% or more in order to maintain the high refractory of the basic influent. Although either sintered magnesia clinker or molten magnesia clinker may be used, in order to obtain high corrosion resistance, it is preferable to use a molten magnesia clinker.

The reason for limiting the particle size of magnesia clinker to 5-1mm size is that when the castable is kneaded with water, the fine powder of 1mm or less has a large specific surface area, so it is highly hydrated by reacting with water. Because it inhibits. Here, limiting the content of magnesia clinker means that the remainder is used as refractory aggregate except for spinel clinker fine powder, calcined alumina powder, and alumina cement and silica flower which are added as binders to prevent fluidity decrease and dry cracking by hydration. In order to obtain high corrosion resistance against molten steel and slag, it is effective to contain a large amount of magnesia. Considering this, the magnesia clinker is preferably 55 to 65% by weight.

Spinel Clinker Powder: 24-34 wt%

As the spinel clinker powder, it is preferable to use a particle size of 0.074 mm or less due to the particle size of the inflow material to have self-flowability. Spinel clinker commonly refers to magnesia-alumina-based spinel clinker. Representative spinel clinkers include, for example, about 28% by weight MgO and about 72% by weight Al2O3.

Spinel clinker powder is added 24-34% by weight, which means using the remainder except for magnesia clinker and ultra finely calcined alumina. Spinel clinker powder should be used within the range of 24 to 34% by weight to effectively prevent cracking during inflow drying and to improve corrosion and infiltration resistance.

Ultra finely calcined alumina: 5-10 wt%

The alumina is preferably used 5-10% by weight of ultra finely calcined alumina of 0.5μm or less. The use of ultra-fine calcined alumina increases the self-flowability of the influent and at the same time acts as a binder to increase the dry strength of the influent. In addition, when used in the hot calcination alumina reacts with magnesia to produce a spinel, and when forming the spinel to give the remaining expansion by volume expansion to obtain structural stability, it is advantageous to suppress the infiltration of molten steel or slag. If less than 5% by weight of such alumina powder is used, the self-flowability of the inflow material is lowered and the dry strength is lowered. If it exceeds 10% by weight, the excess is excessively expanded due to spinel formation, and the slag infiltration effect is reduced, and the autofluidity is not deteriorated. However, when the force is applied during kneading, the kneaded materials are bundled together. It is hard to cause kneading problems.

Alumina Cement: 2-3 wt%

Alumina cement is used for imparting bond strength, and less than 2% by weight is insufficient in strength expression.

Silica flower: 1-3 wt%

Silica flower not only provides fluidity and maintains dry strength, but also maintains bonding strength in the middle temperature range (600-1000 ℃). When the amount is less than 1% by weight, the effect of imparting fluidity and strength is weak. In addition, if the content exceeds 3% by weight, the fluidity is rather low, and a low melting point material of magnesia-alumina-silica-based material is generated, resulting in a decrease in hot strength and corrosion resistance.

In the above basic composition, it is preferable to use the sum of the spinel clinker powder, the ultra finely calcined alumina, the alumina cement, and the silica flower in a fine powder of 0.074 mm in a sum of 35 to 45% by weight. The reason is that when the content of fine powder is less than 35%, it is difficult to express autofluidity, and when the content of the fine powder exceeds 45%, a large amount of kneading water is required and fluidity is lowered. If the sum of these is 35 to 45% by weight, the remaining magnesia clinker is 55 to 65%.

The dispersant added extrapolated to the above basic composition is sodium hexametaphosphate: 0.1-0.4% by weight, and the rapid delaying agent is preferably citric acid: 0.01-0.02% by weight.

Hexamethacrylate: 0.1-0.4% by weight extrapolated

Sodium hexametaphosphate serves as a dispersant in the present invention, when the extra composition is extrapolated to less than 0.1% by weight relative to the basic composition, the fluidity of the inlet is insufficient, and when it exceeds 0.4% by weight, the flowability and corrosion resistance is rather deteriorated.

Citric acid: 0.01-0.02 wt%

Citric acid plays a role of suppressing the fastening of the basic inflow material, but the amount of addition should be adjusted according to the amount of alumina cement used in the present invention, if the out of the range of 0.01-0.02% by weight, the kneading occurs during kneading, causing construction problems.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

To prepare a kneading specimen by adding a certain amount of moisture to the components as shown in Table 1, a self-flow rate and a U-tube experiment were performed to evaluate whether the basic influent has self-flowability.

In this case, the self-flow rate is 100mm inside of the flow cone (flow cone) in the center of the metal plate of the flow meter and filled with about 1Kg of the kneaded sample, and after removing the flow cone, leaving only the mass sample and 30 seconds elapsed The longest part and the shortest part of the sample spread on the plate were measured, and the average value was made into the flow value. If the flow value is usually 180 mm or more, it can be determined that the self-flowability is good.

In addition, the kneaded material was introduced from one side of the 50 mm diameter U-shaped pipe shown in FIG. 1, and the step height of the upper surface of both sides of the kneaded material was measured at the time when the kneaded material stopped moving, and the self-flowability was evaluated. This step measurement indicates that the higher the step height is to zero, the better the self-flowability.

As can be seen from Table 1, in the case of Example (1-4) that satisfies the scope of the present invention, it can be seen that the self-flowability is superior to that of Comparative Example (1-5), which does not satisfy the scope of the present invention. have.

On the contrary, in Comparative Example 1, the magnesia clinker of 5-1 mm size and the spinel powder of 0.074 mm or less did not satisfy the claims, indicating that the fluidity was high and the step was high. The content exceeded the claims and did not express autofluidity. Comparative Example 3 shows that the addition amount of ultra finely divided alumina is outside the claims, and the strength of the specimen is lowered as well as the autofluid. Comparative Example 4 is outside the claims of the particle size of the magnesia clinker and the fine spinel can be confirmed that there is no self-flowability. Comparative Example 5 is outside the claims of the silica flower, it can be seen that the lack of self-flowability and strength.

As described above, the present invention has a useful effect of providing a high-resistance magnesia-spinel form amorphous refractory composition excellent in corrosion resistance and spalling resistance while simplifying construction than existing vibration inflow construction materials.

Claims (2)

It is composed of 24-34% by weight of spinel clinker powder of less than 0.074mm, 2-3% by weight of ultra finely calcined alumina, 2-3% by weight of alumina cement, 1-3.0% by weight of silica flower, and magnesia clinker of 5-1mm size. The basic amorphous form refractory composition which has the self-flow property which adds 0.1-0.4 weight% of sodium hexametaphosphate and 0.01-0.02 weight% of citric acid by extrapolation here. According to claim 1, wherein the spinel powder, ultra-fine alumina, alumina cement, silica flower is a basic amorphous type refractory composition having a self-flow property, characterized in that the total is 35-45% by weight, the size is 0.074mm or less.