KR101011078B1 - Method for Preparing Castable Block Improving Corrosion and Oxidation Resistance - Google Patents

Abstract

The present invention relates to a method for producing a castable block for improving corrosion resistance and oxidation resistance, and the castable block of the present invention is an oxide powder having a particle diameter of 0.010 to 0.075 mm and a carbon-based powder having an average particle diameter of 5 to 20 μm. By mixing strongly with a pulverizer, the oxide powder is first coated with carbon-based particles, and the first coated mixed powder is secondly coated with an aqueous solution composed of 10 to 50% by weight of inorganic material and 50 to 90% by weight of water, and then refractory aggregate It is manufactured by mixing with and degassing, and there is no ubiquitous or loss of carbon particles during degassing, uniformly distributed antioxidants around the carbon particles, providing a castable block excellent in oxidation resistance and corrosion resistance There is an effect that can be suitably used as interior refractories of industrial urinary tract such as cement.

Castable Block, Indefinite Refractory, Carbon Containing, Vibration, Degassing, Interior Refractory

Description

Method for Preparing Castable Block Improving Corrosion and Oxidation Resistance to Improve Corrosion Resistance and Oxidation Resistance

The present invention relates to a method for producing a castable block for improving corrosion resistance and oxidation resistance. More specifically, the method for producing a castable block for improving the corrosion resistance and oxidation resistance by first coating the oxide powder with carbon-based particles by strongly mixing the oxide powder and the carbon-based powder and second coating with the aqueous solution of an inorganic material, and The present invention relates to a castable block which is manufactured by the present invention and can be suitably used as interior refractories of various industrial urinary furnaces such as steelmaking, steelmaking, and cement.

Internal refractories of various industrial urinary tracts can be classified into standard refractory bricks, irregular refractory blocks, and castable blocks. The castable block is a product formed by pouring the amorphous refractory material mixed with a wet shape into a mold of a constant shape, curing and drying to form a regular product, and it is possible to manufacture a denser product than the amorphous refractory material, and the manufacturing cost is lower than that of the standard refractory brick. In addition, it has recently been in the spotlight because it has the advantage of being large in size.

Republic of Korea Patent Application Publication No. 1999-0018884 appropriately controls the graphite added to the amorphous refractory in two forms of finely divided graphite treated with a surfactant and granulated graphite coated with a resin, thereby controlling the strength and amount of moisture of the refractory. Keeping in the range, a large amount of graphite was added to provide a graphite-containing castable refractory having excellent heat resistance, thermal shock resistance, and corrosion resistance.

In addition, Korean Patent Application Publication No. 1993-007007859 adds and kneads 50% of the liquid phenol resin to be added to the refractory raw material having a purity of magnesium oxide (MgO) of 95 to 99% and a particle size of 1 to 5 mm. Artificial and natural graphite and metal powder antioxidant are added and coated, 50% of the remaining liquid phenolic resin is added and kneaded, refractory raw material fine powder having a particle size of 1 to 0.001 mm, pitch powder and Al ₂ O ₃ are added. Magnesia carbonaceous amorphous refractory prepared by kneading is presented.

However, when the castable block is manufactured using the above-mentioned refractory, there is a problem in that the dry specimen has a high porosity, so that there is no effect of adding an antioxidant, and oxidation resistance and corrosion resistance, such as rapid oxidation of graphite, are poor. . In addition, when molding by vacuum degassing using the present refractory, there is a problem such that the graphite particles having a low specific gravity during the degassing rises, or the tissue is uneven due to escape with bubbles.

In order to solve the above problems, an object of the present invention is to provide a method for producing a castable block to improve the oxidation resistance and corrosion resistance.

Another object of the present invention is to provide a castable block having improved oxidation resistance and corrosion resistance.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention is to strongly mix the oxide powder having a particle size of 0.010 to 0.075mm and the carbon-based powder having an average particle diameter of 5 to 20㎛ by a mill, whereby the oxide powder is first coated with carbon-based particles Preparing a mixed powder: preparing a mixed powder secondary coated with an aqueous solution composed of 10 to 50% by weight of inorganic material and 50 to 90% by weight of water; And degassing and molding the secondary coated mixed powder and refractory aggregate. It provides a method for producing a castable block to improve the oxidation resistance and corrosion resistance, characterized in that made.

The mill may be an attrition mill, a ball mill or a jet mill.

The inorganic material may be at least one inorganic material selected from the group consisting of aluminum nitrate, aluminum sulfate, magnesium nitrate, and boric acid.

In addition, the present invention provides a castable block with improved oxidation and corrosion resistance produced by the manufacturing method as described above.

Hereinafter, the present invention will be described in detail.

Method for manufacturing a castable block of the present invention is to improve the corrosion resistance in order to improve the corrosion resistance and poor oxidation resistance of the existing castable refractory used as interior refractory of industrial furnaces such as steel, steel, cement And a step of primary coating the oxide powder with carbon-based particles by strongly mixing the furnace oxide powder and the carbon-based powder, and the second coating with an aqueous solution of an inorganic substance to improve oxidation resistance. have.

The step of preparing a mixed powder in which the oxide powder is first coated with carbon-based particles is a step of strongly mixing an oxide powder of 0.075 mm or less and a carbon-based powder having an average particle diameter of 20 μm or less with a grinder. When the mixing is strong, the carbon-based powder is buried on the surface of the oxide powder by the action of the shear force, and is physically attached strongly. Therefore, there is no separation of oxide particles and carbon-based powders during degassing, no rise of carbon-based particles, and these carbon-based particles improve corrosion resistance of molten steel and slag of the final castable block.

The carbon-based particles are preferably amorphous carbon such as carbon black or pitch, and crystalline carbon such as impression graphite, Kish graphite, expanded graphite, or the like. More preferably crystalline carbon. The oxide powder is preferably magnesia, alumina, silica, calcined alumina, silica flower, or the like. The particle diameter of the oxide powder should be 0.075 mm or less, and the average particle diameter of the carbonaceous powder should be 20 μm or less. When the particle diameter of the oxide powder exceeds 0.075 mm or the average particle diameter of the carbon-based powder exceeds 20 μm, the adhesion rate to the oxide particles is low, so that most carbon-based powders are independently present and become ubiquitous during deaeration molding. As the size becomes larger, the oxidation resistance and the corrosion resistance of the castable block are lowered. The particle size of the preferred oxide powder is 0.010 to 0.075 mm, and the average particle diameter of the carbon-based powder is 5 to 20 µm.

When mixing the oxide powder and the carbon-based powder, it is preferable to use a grinder such as an attention mill, a ball mill, a jet mill, etc., capable of generating a strong shear force.

The step of preparing the secondary coated mixed powder is a step of coating the primary coated mixed powder with an aqueous solution consisting of 10 to 50% by weight of inorganic materials such as aluminum nitrate, aluminum sulfate, magnesium nitrate and boric acid and 50 to 90% by weight of water. to be. When nitrate, aluminum sulfate, magnesium nitrate, and boric acid are mixed with water, a hydrate is formed, and the formed hydrate is strongly attached during the drying process after forming a hydrate layer on the carbon-based primary coating layer. The hydrate layer acts as an antioxidant of the carbon-based particles by thermally decomposing prior to the oxidation of the carbon-based particles, thereby transferring to an oxide to form a dense protective layer on the surface of the carbon-based particles. Therefore, since the hydrate is uniformly coated on the surface of the carbon-based coating layer is to improve the oxidation resistance.

The aqueous solution of the inorganic material is an aqueous solution consisting of 10 to 50% by weight of inorganic material and 50 to 90% by weight of water. If the inorganic material is less than 10% by weight, the amount of hydrate to be coated is small and there is no anti-oxidation effect. If the amount is more than 50% by weight, the coating of the hydrate proceeds unevenly, causing cracking and dropping of the coating layer during the drying process. Therefore, the castable block has low oxidation resistance and corrosion resistance.

The secondary coated mixed powder is mixed with the refractory aggregate at an appropriate ratio, and then degassed to produce a castable block. When the mixed powder and the refractory aggregate are mixed and then degassed, the castable block in which the carbon-based particles are uniformly distributed can be obtained without loss of separation or degassing of the carbon-based particles having low specific gravity. The apparent porosity after drying of the degassed castable block is about 5 to 8%. The method for producing a castable block using a mixed powder and fireproof aggregate is based on the method disclosed in Korean Patent Application No. 2002-0083010.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

Examples 1-4 and Comparative Examples 1-6

Example 1

30% by weight of magnesia powder having a particle diameter of 0.075 mm or less and 10% by weight of ultra fine alumina are mixed with 5% by weight of graphite which has an average particle diameter of 5-20 µm, and then mixed vigorously by a ball mill, and the graphite particles are mixed with the magnesia powder and ultra fine alumina. A mixed powder was obtained which was primarily coated on the surface of the powder. The mixed powder obtained was secondary coated on the mixed powder surface by spraying an aqueous solution composed of 10% by weight of boric acid and 90% by weight of water while stirring. After secondary coating treatment, the mixture was dried by adding warm air from 70 ° C to 100 ° C with continuous stirring.

The dried mixed powder was molded by the method disclosed in Korean Patent Application No. 2002-0083010. That is, 2 weight% of silica flowers, 3 weight% of alumina cement, 0.2 weight% of hexamethaphosphate as a dispersing agent, 50 weight% of magnesia aggregate, and 7 weight% of moisture were mixed. The molding mold was put into a vacuum chamber provided with a vibrator at the bottom thereof, and the vacuum chamber was closed after pouring the mixture into the injected molding mold. By operating the vibrator while depressurizing to several tens of torr, bubbles contained in the mixture were discharged out of the vacuum chamber, and as the bubbles were released, the mixture was densely packed in the mold. After the end of the work, the mold was taken out of the vacuum chamber and kept at room temperature for 12 hours, and then the mold was dismantled to prepare a dense castable block.

The prepared castable block specimen was dried at 100 ° C., and then heat treated at 1,000 ° C. and 1,500 ° C. for 3 hours to measure the weight loss of the specimen.

In addition, the corrosion resistance and oxidation resistance of the specimens were evaluated by rotating erosion test at 1,650 ° C. using steelmaking slag and molten steel as erosion agents, and the values calculated using the results of Comparative Example 1 as 100 are shown in Table 1 below.

[Examples 2 to 4 and Comparative Examples 1 to 6]

As shown in Table 1, the same as in Example 1 except for the oxide powder particle size, the average particle diameter and type of the carbon-based powder, the type and content of the inorganic material, the carbon particle treatment method, the manufacturing method of the castable block After performing, the results are shown in Table 1 below.

On the other hand, the resin coated granulated graphite in Comparative Example 1 used the same as that shown in the Republic of Korea Patent Application Publication No. 1999-0018884.

division Oxide powder
Particle diameter (mm) Carbonaceous powder Mineral aqueous solution Carbon Particle Treatment Castable block Average particle size (㎛)
Kinds Type of mineral Mineral content (% by weight) Recipe Oxidation Resistance Index Corrosion Resistance Index
room

city

Yes One 0.075 or less 20 Impression Boric acid 10 Invention Deaeration Molding 200 190 2 0.075 or less 10 Kish Graphite Magnesium nitrate 30 Invention Deaeration Molding 210 190 3 0.075 or less 5 Kish Graphite Aluminum nitrate 50 Invention Deaeration Molding 220 200 4 0.075 or less 10 Impression Boric acid 20 Invention Deaeration Molding 210 190
ratio

School

Yes One 0.075 or less 20 Impression - - Resin coating Vibration molding 100 100 2 0.075 or less 20 Impression - - Untreated Vibration molding 90 90 3 0.075 or less 15 Impression Boric acid 5 Invention Deaeration Molding 110 110 4 0.075 or less 15 Impression Boric acid 70 Invention Deaeration Molding 105 106 5 1.000 or less 20 Impression Aluminum nitrate 10 Invention Deaeration Molding 115 120 6 0.075 or less 45 Impression Aluminum nitrate 20 Invention Deaeration Molding 110 115

As shown in Table 1, according to the present invention, the particle size of the oxide is 0.075mm or less, the average particle diameter of the carbon-based powder is 5 to 20㎛, 10-50% by weight aqueous solution of boric acid, magnesium nitrate or aluminum nitrate The castable blocks of Examples 1 to 4 prepared by using the degassing molding in the manufacture of castable blocks are 5, 70 of the contents of Preparation Examples 1 and 2, and the inorganic aqueous solution which are not secondaryly coated with the aqueous inorganic solution. It can be seen that the corrosion resistance and the oxidation resistance are much superior to those of Preparation Examples 3 and 4 and Preparation Example 5 having the particle diameter of the oxide powder being 1 mm or less and Preparation Example 6 having the average particle diameter of the carbon-based powder being 45 µm.                     

In addition, the castable blocks of Examples 1 to 4 according to the present invention had no loss of carbon particles.

As described above, the method for manufacturing a castable block according to the present invention is free from ubiquitous or loss of carbon particles during degassing, and is uniformly distributed with antioxidants around the carbon particles, thereby providing excellent oxidation and corrosion resistance. It is a useful invention having the effect of providing a castable block and providing a castable block which can be suitably used as an internal refractory material for industrial urinary furnaces such as steelmaking and cement.

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (4)

Preparing a mixed powder in which the oxide powder is first coated with carbon-based particles by strongly mixing an oxide powder having a particle diameter of 0.010 to 0.075 mm and a carbon-based powder having an average particle diameter of 5 to 20 μm with a grinder: Preparing a mixed powder coated secondly with an aqueous solution composed of 10 to 50% by weight of inorganic and 50 to 90% by weight of water; And Degassing and molding the secondary coated mixed powder and refractory aggregate; Method for producing a castable block to improve the oxidation resistance and corrosion resistance, characterized in that comprises a. The method of claim 1, Method for producing a castable block to improve the oxidation resistance and corrosion resistance, characterized in that the grinder is an Attrition Mill (Ball Mill), Ball Mill (Jet Mill) or Jet Mill (Jet Mill). The method of claim 1, Oxidation resistance and corrosion resistance improvement characterized in that the inorganic material is at least one inorganic material selected from the group consisting of aluminum nitrate (Aluminum Nitrate), aluminum sulfate (Aluminum Sulfate), magnesium nitrate (Magnesium Nitrate), and boric acid (Boric acid) Method of manufacturing a castable block to be. Castable block with improved oxidation and corrosion resistance produced by the manufacturing method of claim 1.