JP2872670B2 - Irregular refractories for lining of molten metal containers - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an amorphous refractory for lining the inner surface of a molten metal container, and in particular, has less cracking and peeling when formed by a casting method and has excellent corrosion resistance. The present invention relates to a lining material composition for a molten metal container that exerts its effect.

[Related Art] Conventionally, as an amorphous refractory material for ladle lining, pyroxene, pyroxene-zircon, quartzite-zircon, zircon, etc. have been mainly used.

On the other hand, in recent years, adoption of vacuum degassing method and continuous casting method,
Furthermore, high-grade steel grades have come to be refined with a ladle in response to improvements in ladle refining techniques. Therefore, it is necessary to perform argon stirring, alloy addition, vacuum processing, etc., and the processing conditions in the ladle are becoming increasingly severe as represented by an increase in the temperature of the molten steel and an extension of the residence time of the molten metal. ing. However, the conventional general-purpose materials as described above cannot cope with such severe conditions, and the life of the ladle is significantly reduced. Furthermore, due to a large amount of outflow components from the refractory due to erosion of the ladle, deterioration of steel quality such as contamination of molten steel and increase of inclusions in steel is becoming a problem.

Therefore, alumina, spinel, magdro, magcarbon, and the like have been used for the purpose of solving the above-mentioned problems of the conventional materials, but none of them have been satisfactory.

[Problems to be Solved by the Invention] First, in the case of alumina material, slag penetrates into the structure greatly, causing structural spalling. In addition, high basicity slag undergoes chemical erosion, and the corrosion resistance is significantly reduced. Problems. In addition, spinel and magdro materials have excellent corrosion resistance, but have a problem of poor thermal spalling resistance due to high hot linear expansion. In addition, carbon-containing materials such as mag-carbon materials have excellent thermal shock resistance, but in addition to carbon pickup into steel, decrease in corrosion resistance due to consumption of carbon due to high FeO slag and high O ₂ level steel, and high heat Remarkable drop in molten steel temperature due to conductivity (heat dissipation), bad smell and dryness when drying due to use of organic binder, and back side (steel side in lining layer)
There is a problem such as fragile deterioration due to oxidation of the metal.

Means for Solving the Problems The present inventors have grasped the advantages of low linear thermal expansion property and low thermal conductivity of alumina and slag erosion resistance of spinel as an advantage. The disadvantage of alumina, which is liable to occur, is compensated for by spinel, while the disadvantage of spinel, which has high hot linear expansion and tends to cause thermal spalling, is compensated for by alumina in view of the fact that both are used in combination. A patent application was separately filed for completing an amorphous refractory for lining a molten metal container having excellent poling properties and corrosion resistance. However, further studies have shown that cracks due to material shrinkage due to self-sintering need to be further improved to prevent this, and if magnesia is added to the above composition, the rise during self-sintering will increase. The present invention was completed by knowing that the magnesia reacts with the alumina at the time of heating to form a secondary spinel, and the appropriate expansion at this time imparts crack resistance. That is, the present invention includes 95 to 5 parts by weight of a heat-resistant raw material containing spinel as a main component with respect to 5 to 95 parts by weight of a heat-resistant raw material containing alumina as a main component. A ternary composition comprising 0.1 to 10 parts by weight of a heat-resistant raw material containing as a main component is used as an aggregate, and alumina cement is used in an amount of 2 parts by weight or less (but not including 0 part by weight) and vaporized silica. Is contained in an amount of 3 parts by weight or less (however, excluding 0 parts by weight).

[Action] In the ladle operation, heating and cooling are repeated. Accordingly, the material may tend to shrink due to slag absorption or self-sintering. In such a case, cracks are generated, and the cracks cause infiltration of the base metal, resulting in peeling of the lining. Therefore, it is desirable to obtain a material with excellent crack resistance and exfoliation resistance as a ladle lining material. To that end, not only is it excellent in slag penetration resistance, but also the hot linear expansion of the material itself It is also important to reduce the rate. When only the alumina-based material is used as the main aggregate, the resistance to thermal spalling is excellent due to low hot linear expansion, but structural spalling occurs due to poor slag penetration resistance as described above. Easy to do. On the other hand, when only the spinel-based raw material is used as the main aggregate, on the other hand, structural spalling hardly occurs, but thermal spalling tends to occur. In the present invention, one of the main points is to skillfully combine these advantages and disadvantages.

The second essential point of the present invention resides in providing a residual expandability. That is, although the penetration resistance of the slag is improved by the blending of the spinel as described above, the tendency of the material to shrink during self-sintering cannot be completely improved. Thus, in the present invention, the refractory material is made to have an intumescent property, that is, a residual inflation property is imparted. This performance is the ability of the refractory material to heat, especially the material expanding, thereby trying to counteract the tendency of alumina to shrink. In order to provide the residual expansibility, the magnesia-based raw material is mixed with the above-mentioned aggregate component, and the magnesia and the alumina are reacted with each other at a high temperature during use to produce a secondary spinel. However, when the amount of the secondary spinel exceeds a proper amount, abnormal expansion is caused, and the apparent porosity is increased, which promotes slag infiltration or causes blistering of the working surface side sintered layer. Generally, the amount and rate of formation of the secondary spinel are controlled by the particle size and the amount of magnesia, and a small particle size and / or a large amount of addition promotes the formation of the secondary spinel.

Next, the heat-resistant raw material used in the present invention will be described. First, as an alumina-based raw material, a material which has a small amount of impurities and is subjected to a high temperature treatment is preferable, and examples thereof include fused alumina, sintered alumina and calcined alumina. Natural bauxite and bread soil shale are poor in corrosion resistance because they contain many impurity components such as SiO ₂ and TiO ₂ , but can be used in some cases because of low cost. As the spinel-based raw material, commercially available high-purity fused spinel and sintered spinel are recommended. However, entry of impurities is not necessarily excluded. Next, as the magnesia-based raw material, a material containing as little impurities as possible and having a stable reactivity, such as electrofused magnesia and seawater magnesia clinker, is preferable. Natural magnesia and the like have a large amount of flux components, so that not only the effect of imparting expansion characteristics by the formation of the secondary spinel according to the present invention is insufficient, but also the corrosion resistance and spalling resistance are deteriorated. Therefore, in the present invention, the expression of a heat-resistant raw material containing alumina or spinel as a main component or a heat-resistant raw material containing magnesia as a main component is adopted.

These heat-resistant raw materials are used after being pulverized, but are generally prepared by dividing into relatively large particles and relatively small particles in order to reduce the porosity at the time of mixing. Therefore, each raw material is divided into such two series of particle sizes, but one raw material can have a large particle size as the center and the other raw material can have a small particle size. In this case, spinel is the main component. In order to improve the penetration resistance of the slag, it is desirable to increase the amount of fine particles from the viewpoint of promoting the formation of secondary spinel as described above.

Next, the mixing ratio of these heat-resistant raw materials will be described.
First, regarding the mixing ratio of the alumina-based raw material and the spinel-based raw material, when the former is 100 parts by weight, the alumina-based raw material is 5 to 95 parts by weight, and the remaining 95 to 5 parts by weight is the spinel-based raw material. More preferably, the amount of the alumina-based raw material is 15 to 85 parts by weight. If the amount of the alumina-based material is less than 5 parts by weight, the spinel composition increases, the hot linear expansion coefficient as a casting material increases, and the spalling resistance decreases due to the increase in thermal conductivity, and the amount of secondary spinel generated decreases. In addition, the residual swellability is reduced, and cracks are easily generated. Conversely, if the amount of the alumina-based material is more than 95 parts by weight, the slag penetration resistance and the corrosion resistance decrease because the spinel composition decreases.

The addition ratio of the magnesia-based material is 0.1 to 10 with respect to the total amount (100 parts by weight) of the alumina-based material and the spinel-based material.
Parts by weight, preferably 1 to 8 parts by weight. In terms of the weight ratio with respect to the alumina-based raw material, it is desirable that the weight ratio is in the range of 1:20 to 1: 5 and is closer to the alumina side than the spinel composition value.
If the amount is less than 0.1 part by weight, the effect of imparting expandability is not obtained. If the amount exceeds 10 parts by weight, the structure becomes porous due to abnormal expansion, and the corrosion resistance and spalling resistance decrease. The particle size is adjusted according to the use conditions so that an appropriate expansion rate can be obtained.

In the present invention, a three-component aggregate of alumina-spinel-magnesia is formed from the above three kinds of raw materials, and an amorphous refractory is produced by blending a fourth component, which is generally called an outer shell, to form a binder. Among them, those containing 2 parts by weight or less of alumina cement among conventionally used inorganic binders, and high alumina cement are desirable. As described above, the use of the organic binder is not preferable because it has disadvantages such as a bad smell at the time of drying, a smoke emission, a deterioration due to oxidation of the back side, and a repair of the thigh. Inorganic binders other than the alumina cement include sodium silicate, colloidal silica,
Amine silicate, alumina sol, sodium phosphate, aluminum phosphate, aluminum phosphate modified product and the like can be used. In particular, the product strength can be further improved by adding vaporized silica.

[Examples] Examples 1 to 5 Aggregates for cast materials of the present invention were manufactured using sintered alumina and sintered spinel at the compounding ratios (parts by weight) shown in Table 1.

3 parts by weight of vaporized silica, 2 parts by weight of high alumina cement, and 0.1 part by weight of a phosphate (dispersant) are blended and mixed with 100 parts by weight of the above refractory raw material aggregate, and water is added in an appropriate amount (flow value: 180). After kneading, the mixture was poured into a metal frame of 40 mm x 40 mm x 160 mm. Temperature 2
After curing at 0 ° C. and a humidity of 90% or more for 24 hours, they were dried at 150 ° C. for 24 hours and subjected to a test. Table 1 shows the results of the performance test of the obtained cast material of the present invention.

Comparative Examples 1 to 3 A casting material of a comparative product was manufactured according to the examples and subjected to a performance test. Table 1 shows the results. The test method was as follows.

(1) The physical properties (apparent porosity, bulk specific gravity) of the dried sample and the sample fired in an electric furnace at 1500 ° C. for 3 hours were measured.

(2) The strength characteristics (bending strength) of the dried sample and the sample fired in an electric furnace at 1500 ° C. for 3 hours were measured.

(3) The linear change rate after firing at 1500 ° C. for 3 hours in an electric furnace was measured.

(4) Using a converter slag by a rotary drum type erosion test, a corrosion resistance test was performed at 1650 ° C. × 2 hours, and the erosion depth and the immersion depth were measured.

(5) Repeat the cycle of inserting the sample into an electric furnace maintained at 1000 ° C. for 10 minutes, and then air cooling for 10 minutes.
The number of times until crack generation was examined.

From the above results, it can be seen that the cast material of the present invention is superior in corrosion resistance and spalling resistance as compared with conventional alumina-based and spinel-based materials.

[Effect of the Invention] Since the amorphous refractory for lining a molten metal container of the present invention is constituted as described above, it has excellent spalling resistance as compared with a conventional alumina-based or spinel-based amorphous refractory. And it has corrosion resistance and is most suitable as a lining refractory for various scouring furnaces such as ladles.

Continuation of the front page (56) References JP-A-1-87577 (JP, A) JP-A-60-60986 (JP, A) JP-A-53-134012 (JP, A) JP-A-61-219764 (JP) , A)

Claims (1)

(57) [Claims] A heat-resistant raw material containing alumina as a main component.
Heat-resistant raw material mainly composed of spinel
In addition to 95 to 5 parts by weight, a ternary composition obtained by mixing 0.1 to 10 parts by weight of a heat-resistant raw material containing magnesia as a main component with respect to the total amount of 100 parts by weight is used as an aggregate. Characterized in that it contains 2 parts by weight or less (but does not include 0 parts by weight) and 3 parts by weight or less (but does not include 0 parts by weight) of vaporized silica. .