KR19980052567A - Magnesia-alumina-carbon basic bricks for ladle - Google Patents

Abstract

The present invention relates to a magnesia-alumina-carbon basic brick for ladle, the particle size of 3-1mm electrolytic magnesia clinker 27-29wt%, the particle size of 1mm or less electrolytic magnesia clinker 29-31wt%, fine sintered magnesia clinker 4-6wt %, 12-14wt% of 3-1mm electrolytic alumina, 9-11wt% of electrolytic alumina of 1mm or less in particle size, 100wt% of raw material consisting of 6-8wt% of fine electrolytic alumina, 6-8wt% of 85% graphite, and aluminum It is composed of additives composed of 1-3wt%, 0.5-2wt% of silicon, 0.5-2wt% of carbon powder, and binder of 3-4wt% of binder phenolic resin, which is a condition required for fire bricks especially applied to ladle walls or floors. In order to give mechanical strength and abrasion resistance, high residual expansion, thermal shock resistance and structural stability, the raw materials and various additives are selected and added, and the spalling property, which is a disadvantage of magnesia-carbon brick, is improved, and high residual linear expansion property Granted to that effect.

Description

Magnesia-alumina-carbon basic bricks for ladle

The present invention relates to a magnesia-alumina-carbon basic brick, and more particularly, to a magnesia-alumina-carbon basic brick for ladles to which spalling resistance and high residual linear expansion are given.

In general, the bottom or wall portion of the furnace used in the steelmaking process is a place where the stress is concentrated, causing severe melting loss. In other words, the bottom and wall of the furnace are accompanied by abrasion by molten steel, spalling phenomenon, which is a surface peeling shape due to stress concentration and penetration of molten steel and slag, and thermal spalling after tapping. Because of the accompanying part, particularly high strength, high corrosion resistance and low sintering is required.

As a brick material, hyalumina, alumina-magnesia carbon, and magnesia-carbon refractory are predominant, and magnesia-carbon refractory is not suitable for quantitative blending of magnesia clinker and various additives. There is a problem that the furnace is initially melted due to the inability to exhibit oxidizing and corrosion resistance.

In particular, the refractory material used for ladle includes erosion by hot molten steel, abrasion due to prolonged molten steel retention, spalling and joint formation caused by long time tolerances and temperature changes, and damage caused by carbon oxidation of the refractory material. Will occur.

Accordingly, the present invention has been made to solve the above problems, the present invention relates to a brick applied to the ladle wall or floor in particular, the requirements of mechanical strength and wear resistance, high residual thermal expansion resistance And select and add raw materials and various additives to impart structural stability, improve spalling property, which is a disadvantage of magnesia-carbon bricks, and provide magnesia-alumina-carbon basic bricks for ladles to which high residual linear expansion is imparted. Has its purpose.

In order to achieve the above object, the present invention has a particle size of 3-1 mm electrolytic magnesia clinker 27-29 wt%, a particle size of 1 mm or less electrolytic magnesia clinker 29-31 wt%, fine sintered magnesia clinker 4-6 wt%, particle size 3-1 100 wt% of raw material consisting of 12-14wt% of mm alumina, 9-11wt% of particle size of 1mm or less, 6-8wt% of fine granules of alumina, 6-8wt% of 85% graphite, 1-3wt% of aluminum, silicon It is characterized by consisting of an additive consisting of 0.5-2wt%, 0.5-2wt% carbon powder, and a binder consisting of 3-4wt% binder phenol resin.

In another embodiment of the present invention, a particle size of 3-1 mm electrolytic magnesia clinker 22-24 wt%, a particle size of 1 mm or less electrolytic magnesia clinker 27-29 wt%, fine sintered magnesia clinker 9-11 wt%, 3-1 mm electrolytic alumina 16-18 wt%, 12-14 wt% of molten alumina with a particle size of 1 mm or less, 100 wt% of raw material consisting of 6-8 wt% of 85% graphite, aluminum 1-3 wt%, 0.5-2 wt% silicon, and 1-3 wt% carbon powder. It is characterized by consisting of an additive consisting of, and a binder consisting of a binder phenol resin 3-4wt%.

1 is a comparative diagram illustrating the difference in compressive strength of each Example and Comparative Example

Figure 2 is a comparison diagram illustrating the difference between the oxidation reduction rate and the residual line change rate of each Example and Comparative Example

Figure 3 is a comparison diagram illustrating the difference in the erosion length of each Example and Comparative Example

Hereinafter, preferred embodiments of the present invention will be described in detail.

In order to select an appropriate amount of additives to be added to the formulation, first, in order to develop basic bricks for ladle walls, the graphite content is added in order to reduce heat dissipation and to impart mechanical strength, abrasion resistance, thermal shock resistance and structural stability, which are required characteristics. As a result of the titration test with varying%, the optimum content range of graphite, which could be close to the required characteristics of ladle wall or floor bricks, was selected from 7 to 10%.

In addition, as a result of comparing the maximum particle size 3mm and 5mm through the optimum particle size composition test, the application of the particle size of 3mm showed excellent properties in terms of physical properties.

In addition, in order to give mechanical strength and structural stability, thermal shock resistance, and high residual linear expandability, the addition of alumina to improve the spalling property by spinel formation, alleviate joint erosion, and provide the proper content of alumina to impart continuous residual linear expandability. As a result of changing the alumina content from 0 to 40% through the test for the test, the general physical properties of the test product were insignificant as the alumina content was increased, and the corrosion resistance was decreased as the content increased, and the alumina content was 40%. Was the least corrosion resistant.

TABLE 1

(Unit: wt%)

Table 1 is a design of a test box of magnesia-alumina-carbon brick, and is designed as follows to give the required characteristics. In order to reduce heat dissipation, 7-10% of graphite is added, and the particle size of kneaded material is densely mixed to give mechanical strength, and spinel is formed by adding alumina for high residual linear expansion rate. A dedicated alumina was applied to give high corrosion resistance to existing bricks. The graphite content of Specimen A applied to each specimen was 7%, and it was designed to be dense of 3mm using magnesia as the main agent, and the alumina content was relatively good in the alumina titration test. % To 1 mm and 1 mm or less were used to improve the spinelation reactivity. In the case of specimen B, an electrolytic magnesia clinker was used to improve the corrosion resistance of the 5 mm compound. In the case of specimen C, the content of graphite was changed to 7-10%, and in the case of specimen D, a special carbon for improving spalling resistance. Powder was added, and specimen E was applied with alumina fine powder for promoting the spinel formation reaction, and the alumina content of specimen F was changed to 20 to 30%.

TABLE 2

Table 2 shows the first test results showing the general physical properties of each test piece, the volume specific weight of the test product was found to be about 3. 1 by the use of alumina and the reduction of the amount of graphite, test specimen 4 applied with a special carbon powder In the case of a slight decrease. In case of compressive strength, it showed much better strength characteristics than ordinary magnesia-carbon bricks. The properties measured after reduction firing were also better than those of magnesia-carbon bricks, especially the results of compressive strength measurements. This is due to the combination of particle size design and metal additive composition for strength.

In addition, specimen B, which is a 5 mm blend, showed the lowest inferiority, especially specimen E showed a very high room temperature bending strength value, and specimen D showed the best bending strength value in the specimen. The application of carbon powder resulted in a decrease in the value of hot bending strength after reduction firing and hot rolling, and the value of bending strength after hot and reducing firing was generally superior to that of current magnesia-carbon bricks, which was due to the spinel by aluminum addition. This is due to the densification of tissue by the production reaction.

In addition, as a result of measuring the weight loss rate, the weight reduction rate was increased in the case of C which increased the content of graphite, and the weight reduction rate was also increased in the case of D, which applied 2% of special carbon powder. Overall, the oxidation resistance was evaluated to be superior to the current magnesia-carbon brick due to the effect of blocking the atmosphere from the outside by the spinel formation by aluminum addition and the resulting volume expansion and densification.

In addition, as a result of compressive strength measurement after oxidation test, E and F showed comparable levels compared to the reference compound A. The residual linear expansion rate due to spinel formation was the highest in E with aluminum fine powder, and sustained more than 0.3%. Residual line expansion ratio was the same as that of A. As a result of corrosion resistance test, C added with graphite showed the best result. In spalling test, C, D, and E showed good results without cracking. In the case of, the deterioration of tissue due to the application of special carbon powder was severe compared to other test specimens.

As a result, as a result of the first test, the volume specific gravity was about 3. 1 by the use of lumina and the decrease of the amount of graphite used, and was slightly lower in the case of a test product to which a special carbon powder was applied. In terms of compressive strength, the application of metal additives for the strength improvement and the compact design showed excellent strength characteristics. In the bending strength measurement, B, the 5mm compound, was inferior, and D, which applied special carbon powder, And the bending strength after reduction firing did not decrease. The test product showed excellent hot bending strength after reducing firing compared to the current magnesia-carbon, and the residual line change rate showed a continuous expansion due to the addition of alumina compared to the magnesia-carbon brick. The more it was effective, the more effective it was to promote the densified formulation and the spenylation reaction with a particle size of 3 mm.

TABLE 3

(Unit: wt%)

Hereinafter, more specific examples and comparative examples of the present invention will be described.

Example 1

Particle size 3-1mm electrolytic magnesia clinker 23wt%, particle size 1mm or less electrolytic magnesia clinker 30wt%, fine sintered magnesia clinker 10wt%, particle size 3-1mm electrolytic alumina 7wt%, particle size 1mm or less electrolytic alumina 17wt%, fine grain 100 wt% of a raw material consisting of 13 wt% of molten alumina, 7 wt% of purity 85% graphite, an additive consisting of 2 wt% of aluminum, 2 wt% of silicon, and 1 wt% of special carbon powder, and a binder comprising 3.4 wt% of a binder phenol resin. Magnesia-alumina-carbon basic bricks for ladle.

Example 2

Grain size 3-1㎜ Electrolytic Magnesia Clinker 28wt%, Grain Size 1mm or Less Electrolytic Magnesia Clinker 30wt%, Fine Grained Magnesia Clinker 5wt%, Grain Size 3-1mm Electrolytic Alumina 13wt%, Grain Size 1mm or less Electrolytic Alumina 10wt%, Fine Grain 100 wt% of a raw material consisting of 7 wt% of electrolytic alumina, 7 wt% of purity, graphite, an additive consisting of 2 wt% of aluminum, 1 wt% of silicon, and 1 wt% of special carbon powder, and a binder of 3.4 wt% of binder phenol resin. Magnesia-alumina-carbon basic bricks for ladle.

Comparative example

43wt% of molten magnesia clinker with particle size of 3-1mm, 42wt% of molten magnesia clinker with particle size of 1mm or less, 8wt% of particulate sintered magnesia clinker, purity of 85%, 7wt% of graphite, 2wt% of aluminum, 1wt% of silicon, A magnesia-alumina-carbon basic brick for ladle, comprising an additive consisting of a special carbon powder of 1 wt% and a binder consisting of a binder phenol resin of 3.4 wt%.

TABLE 4

Figure 1 shows the oxidation test results, the oxidation test was carried out for 5 hours at 1400 ℃, atmospheric atmosphere, the comparative example showed the best compressive strength.

Figure 2 shows the results of the residual line change rate test, the residual line expandability is the test article to which the alumina is applied Example 1, Example 2 shows a high residual line expansion rate compared to the comparative example without the alumina applied addition of alumina Was effective in controlling joint opening in use, a disadvantage of magnesia-carbon bricks. At this time, Example 2 to which the alumina fine powder was applied was continuously large.

In addition, after the test piece was reduced and fired at 1200 ° C. for 3 hours to test the spalling resistance, the spalling test result of air cooling in the high frequency induction furnace showed no cracking or dropping. The results are shown.

Figure 3 shows the corrosion resistance test results, the rotary erosion test results showed that the comparative example without alumina showed the best corrosion resistance.

As a result of the first test and the second test, for the ladle, it is possible to increase the corrosion resistance for suppressing slag infiltration, and to apply the C which shows excellent results in joint prevention of preliminary melting and high strength and wear resistance, and for ladle walls or floors. In addition, it was effective to apply Example 2 (test piece E), which can not only satisfy the required characteristics of the ladle wall, but also have high thermal shock resistance and minimize oxidation resistance and carbon pick-up.

As described above, the magnesia-alumina-carbon basic brick for ladle according to the present invention showed an excellent effect in terms of oxidation resistance and strength, which is required by adding graphite of 7%. It showed continuous high residual linear expansion without deterioration of properties, and by applying special carbon powder of 1%, it has the effect of improving spalling property without deterioration of content.

Claims (2)

Particle size 3-1㎜ electrolytic magnesia clinker 27-29wt%, particle size below 1mm electrolytic magnesia clinker 29-31wt%, fine sintered magnesia clinker 4-6wt%, particle size 3-1㎜ electrolytic alumina 12-14wt%, particle size 1mm 100wt% raw material consisting of 9-11wt% of electrolytic alumina, 6-8wt% of fine granules, 6-8wt% of 85% graphite, aluminum 1-3wt%, 0.5-2wt% of silicon, 0.5-2wt% of carbon powder Magnesia-alumina-carbon basic bricks for ladle, characterized in that consisting of an additive consisting of, and a binder consisting of a binder phenol resin 3-4wt%. Particle Size 3-1㎜ Electrolytic Magnesia Clinker 22-24wt%, Particle Size 1mm or Less Electrolytic Magnesia Clinker 27-29wt%, Fine Sintered Magnesia Clinker 9-11wt%, 3-1㎜ Electrolytic Alumina 16-18wt%, Particle Size 1mm or Less 100 wt% of raw material consisting of 12-14 wt% of molten alumina, 6-8 wt% of graphite, additives consisting of 1-3 wt% of aluminum, 0.5-2 wt% of silicon, and 1-3 wt% of carbon powder, and binder phenol resin 3- Magnesia-alumina-carbon basic brick for ladle, characterized in that consisting of a binder consisting of 4wt%.