KR100303871B1 - refractories for metal mixing cart ladle and method for preventing oxidation of carbon there of - Google Patents

Abstract

The present invention is a refractory brick for preventing the oxidation of carbon contained in the refractory brick generated during preheating of the molten iron and molten steel ladle for the molten iron cross-car or molten steel ladle made of carbon-containing refractory bricks to increase the service life And a carbon oxidation prevention method for firebrick.

According to this configuration, a refractory brick coated with an antioxidant on at least a refractory brick containing carbon and preheating the refractory brick at a temperature of 700 to 1,500 ° C. have the coating layer grazed and formed into a glass phase. A technique relates to a method for preventing oxidation of carbon in the interior.

Description

Refractories for metal mixing cart ladle and method for preventing oxidation of carbon there of}

The present invention relates to a refractory brick that is built in a cross-flow difference or molten steel ladle of molten iron pretreatment, and more specifically, by coating an antioxidant on a surface of a carbon-containing refractory brick, The present invention relates to a method for preventing carbon oxidation of refractory bricks and refractory bricks by inhibiting carbon oxidation of refractory bricks generated during preheating to increase corrosion life.

Ladle refractory bricks for steelmaking and refractory bricks for crosstalk cars for the purpose of pretreatment and transportation of molten iron are carbon-containing raw materials to improve corrosion resistance, spalling resistance and infiltration resistance to molten steel and molten iron. Phosphorous firebrick is used.

For example, in the case of a mixed tea, it is composed of 50 to 80 parts by weight of alumina, 5 to 20 parts by weight of silicon carbide, 5 to 20 parts by weight of carbon and other components, and 50 to 80 parts by weight of alumina and 1 to 49 for magnesia. It is composed of parts by weight, 5 to 20 parts by weight of carbon, and other components.

However, carbon-containing refractory bricks exhibit excellent corrosion resistance and infiltration resistance, but have a disadvantage in that carbon is oxidized to oxygen in the air.

That is, when carbon is oxidized, the structure of the refractory brick is destroyed, and the role of carbon is lost due to the increase in porosity, so that the refractory brick is easily damaged by molten steel.

In order to prevent such oxidation, there is a method of adding metal powder, frit, boron compound, and the like into the composition when preparing a refractory brick containing carbon.

The refractory bricks are used to build a crossroad or ladle.

If the molten steel or molten iron of the high temperature state is immediately poured into the cross-construction difference and the ladle of the normal temperature state, the thermal shock or heat loss is caused by a sudden temperature difference.

Therefore, before injection of molten steel and molten iron, the crosstalk difference and the ladle are preheated to about 900 to 1300 ° C.

However, the above-mentioned carbon-containing refractory bricks or refractory bricks added with antioxidants have the effect of delaying oxidation in the process of using them, and thus can not fundamentally suppress the oxidation occurring in the preheating stage of the built-in. In pretreatment or ladle refining, the erosion of the refractory brick is increased, resulting in a decrease in service life.

The present invention is to improve the above-mentioned conventional problems, by applying an antioxidant to the surface of the refractory brick containing a carbon-containing refractory brick or an antioxidant added thereto, the glass coating is grazed in the pre-heating step (Glazing) The purpose of the present invention is to increase the service life by blocking air infiltration and suppressing brick damage caused by oxidation of carbon.

The present invention for achieving the above object consists of a cross-car and a ladle built-in refractory brick coated with an antioxidant on the surface of the refractory brick containing at least carbon formed on the cross-car or ladle inner surface.

In coating the antioxidant, an antioxidant may be coated on the surface of the refractory brick of a single unit manufactured through a conventional process, and the coated refractory brick may be constructed on the cross surface of the crosstalk and ladle, and the antioxidant may be An uncoated refractory brick may be constructed on the cross-section and ladle inner surfaces and then coated with an antioxidant on the surface.

At this time, the coating method may be all spray method or brushing method.

In using the built-in crosstalk and ladle (ie, injecting molten iron and molten steel), the interior is preheated to 700 to 1500 ° C before use.

At this time, the coating layer of the antioxidant is grazed in the temperature rising process to become a glass coating form to block the penetration of air to inhibit the oxidation of carbon.

The antioxidant is not limited to any one specified as possible as long as it is a composition that can be grazed upon heating between 700 to 1500 ° C. As an example, 30 to 75 parts by weight of SiO ₂ , 1 to 10 parts by weight of B ₂ O ₃ , or ZrO ₂ and 50 to 60 parts by weight of one or more, Al ₂ O ₃ 1~10 weight in part, may be mentioned as the other, the sum of Na ₂ O and N ₂ O 6 to 20 parts by weight of the composition.

Since antioxidants have a property of melting at low temperatures, the antioxidants can be applied up to 1500 ° C by lowering the temperature to 700 ° C or lower than conventional preheating conditions.

The coating thickness is preferably in the range of 0.2 to 1.0 mm, and if the thickness is too thick, the flowing property or bite occurs when the antioxidant is grazed, and if the thickness is too thin, the surface of the brick is partially The uncoated portion of the exposed or grazed glass is generated, which results in less carbon antioxidant effect and lower corrosion resistance.

In general, in preparing a carbon-containing refractory brick, raw materials → kneading → aging → molding → heat treatment to obtain a refractory brick, which is used after construction → preheating (ie, injection of molten metal). In coating process, the coating sequence can be applied in any process, such as molding → antioxidant coating → heat treatment → construction, molding → heat treatment → antioxidant coating → construction, or coating an antioxidant on the surface of the refractory brick that has been constructed through the existing process. It's all possible.

The following is described according to the embodiment.

Example 1

Refractory brick is alumina: 71.7 parts by weight, silicon carbide: 11.7 parts by weight, carbon: 14.2 parts by weight, other: the remaining components, and the molded by a known method to make a brick, the oxidation of the (A) component of Table 2 on the surface 20 to 50 parts by weight of water was added to 100 parts by weight of the inhibitor, followed by coating by brushing method.

After the heat treatment in a conventional manner and the heat-resistant firebrick was built in the crossroad car was subjected to a pre-heating treatment at 1200 ℃ 24 hours at a temperature rising rate of 100 ℃ / hour.

As a result, as shown in Table 2, the present invention, in which the antioxidant was coated, did not produce any oxide layer, but when the preheating was performed using only the refractory brick component not coated with the antioxidant, the thickness of the oxide layer was 23 mm.

The molten iron and slug tapping out of the induction melting furnace were charged into the preheating crosstalk, and the depth damaged by the molten iron after heating at 1550 ° C. for 10 hours was measured.

As a result, in the case of the present invention was about 0.3 ~ 0.45mm per hour, the existing case was found to be 2.4 ~ 2.8mm per hour.

The results according to this example are shown in Table 3.

Example 2

Firebrick: 68.8 parts by weight of alumina, 10.7 parts by weight of silicon carbide, 12.7 parts by weight of carbon, other components

Antioxidant: Table 2 (b)

Coating method: Spray coating (100 parts by weight of antioxidant + 30-50 parts by weight of water)

Preheating: same as Example 1

As a result of measuring the erosion depth in the same manner as in Example 1, it was shown in Table 3.

That is, in the present invention after preheating, the oxide layer was not formed, but the thickness of the oxide layer was 32 mm in the case of the conventional comparative invention, and in the case of the erosion depth, the present invention was 0.3-0.45 mm per hour, but in the conventional case, the thickness was 3.5-3.8 mm. .

Example 3

Firebrick: 74.8 parts by weight of alumina, parts by weight of magnesia, 7 parts by weight of carbon, other components

Antioxidant: (A) of Table 2

Coating method: same as Example 1

Other conditions were shown in Table 3 the results of applying in the same manner as in Example 1.

Examples 4-8

The composition of the refractory brick and the composition of the antioxidant were selected as shown in Table 2, and other methods were carried out under the same conditions as in Example 1.

The results are shown in Table 3.

Comparative Examples 1 to 8

The composition of the refractory brick was as shown in Table 3, and the other implementation and test methods were performed as in Example 1.

The results are shown in Table 3.

As can be seen from the above examples and comparative examples, the present invention, in which an antioxidant is coated on the surface of a refractory brick, does not produce an oxide layer because carbon contained in the refractory brick is not oxidized during preheating, and thus, the corrosion resistance is improved. In the case of a mixed vehicle, the service life is increased by about 100 times or more, and in the case of a ladle, about 10 times or more.

Refractory Brick Composition end I Chemical composition (parts by weight) Alumina 50-80 50-80 Silicon Carbide 5-20 1 to 49 Carbon 5-20 5-20 Etc Remarks For crossroad cars For ladle

Antioxidant Composition and Temperature Range end I All la Chemical composition (parts by weight) SiO ₂ 70 75 60 37 Na ₂ O + K ₂ O 18 13 20 10 Al ₂ O ₃ 5 10 9 0 B ₂ O ₃ 2 One 10 - ZrO ₂ - - - 50 Grazing temperature About 900 ℃ About 1050 ℃ About 700 ℃ About 1300 ℃ Temperature range 800-1300 ℃ 950-1400 ℃ 700-1250 ℃ 1250-1450 ℃

sample Brick component (Table 1) Antioxidants (Table 2) Oxide layer thickness (mm) Oxidation layer erosion (mm / hour) Coating layer erosion (mm / hour) Inventive Example One end end - - 0.3-0.45 2 I I - - 0.3-0.45 3 I end - - 0.5-0.7 4 Example 2 I - - 0.5-0.7 5 Example 1 All 4 - 0.5-0.8 6 Example 1 la 5 - 0.6-0.9 7 Example 2 All 6 - 0.8-1.2 8 Example 2 la 7 - 1.0-1.5 Species comparison One Example 1 - 23 2.4-2.8 - 2 Example 2 - 32 3.5-3.8 - 3 Example 2 - 29 3.2-3.5 - 4 Example 2 - 29 3.2-3.5 - 5 Example 1 - 23 2.4-2.8 - 6 Example 1 - 32 3.5-3.8 - 7 Example 2 - 29 3.2-3.5 - 8 Example 2 - 29 3.5-3.2 -

As described above, the present invention is coated with an antioxidant on the surface of the carbon-containing inner masonry, which is built inside the cross-cut car and the ladle, and thus, during the preliminary treatment of the molten iron due to the oxidation of carbon generated in the preheating step, which is before the molten iron and molten steel injection. And it can increase the service life of the refractory brick by strengthening the corrosion resistance during molten steel refining.

Claims (6)

In the refractory brick containing at least carbon used for the construction of molten iron and molten steel casting container, 30-75 parts by weight of SiO ₂ , 6-20 parts by weight of Na ₂ O and K ₂ O, 1-10 parts by weight of B ₂ O ₃ or 50-60 parts by weight of ZrO ₂ to prevent oxidation of carbon on the refractory brick surface Refractory brick, characterized in that the coating is made of an antioxidant composed of at least one part, Al ₂ O ₃ 1-10 parts by weight. The method of claim 1, Refractory brick, characterized in that the antioxidant coating layer is formed on the surface of the refractory brick. In the refractory brick containing at least carbon used for the construction of molten iron and molten steel casting container, 30-75 parts by weight of SiO ₂ , 6-20 parts by weight of Na ₂ O and K ₂ O, 1-10 parts by weight of B ₂ O ₃ or 50-60 parts by weight of ZrO ₂ to prevent oxidation of carbon on the refractory brick surface At least one of the parts, Al ₂ O ₃ 1 to 10 parts by weight of the antioxidant composition is coated, and then preheated to the coating layer is glazed (Glazing) characterized in that to form a glass coating Carbon Antioxidation Method. The method of claim 3, wherein Carbon oxidation prevention method of the refractory brick, characterized in that the coating is made on the surface of the refractory brick. The method of claim 1, A refractory brick, characterized in that the molten iron and the molten steel casting container are stacked in a cross talk car. The method of claim 1, Refractory brick, characterized in that the container for casting molten iron and molten steel is ladle.