JPH08183671A - Reformed magnesia fine powder for monolithic refractory and magnesia-containing monolithic refractory - Google Patents

Abstract

PURPOSE: To obtain alumina reformed magnesia fine powder superior in slaking resistance. CONSTITUTION: This reformed magnesia fine powder for monolithic refractory is formed by directly sticking alumina fine powder on magnesia fine powder. The monolithic refractory is obtained by incorporating 4-40wt.% of the alumina reformed magnesia fine powder obtained by directly sticking the alumina fine powder on the surface of magnesia fine powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modified magnesia fine powder for amorphous refractory having excellent digestion resistance and a magnesia-containing amorphous refractory using the same.

[0002]

2. Description of the Related Art In recent years, refractory materials used in metallurgical furnaces have been shifting from bricks to amorphous refractory materials for the purpose of saving labor and energy. In the case of irregular-shaped refractory, it has the characteristic of less erosion of metal and slag because it can easily form a jointless structure by integral construction, and it has a heat-resistant spalling resistance compared with conventional refractory bricks. This is because it has the characteristics of excellent and long life.

A typical example of such an irregular refractory material is a castable refractory material that is kneaded with water to give a proper fluidity and then constructed by fluidized filling. It is customary to add refractory fine powder to the castable refractory in addition to refractory aggregates as a skeletal component. This refractory fine powder has various useful actions such as peptization-consolidation by self-hardening due to aggregating action, blockage of fine pores, and imparting fluidity during construction, and therefore, in castable refractories. It is one of the most important refractory materials that is indispensable.

[0004]

However, among the above refractory fine powders, particularly when magnesia fine powders are used for castable refractories, there is a problem of digestion caused by hydration reaction. That is, in this magnesia, Mg ²⁺ ions are easily eluted due to the reaction with water, which causes rapid aggregation of castables, impedes fluidity, and causes deterioration of workability due to solidification. There was a point. Of course, attempts have been made to solve these problems, for example, the use of various cation sequestering agents, but the fact is that they have not yet been sufficiently effective. An object of the present invention is to provide an alumina-modified magnesia fine powder having excellent digestion resistance, and a magnesia-containing amorphous refractory having excellent workability using the same.

[0005]

Means for Solving the Problems As a result of repeated studies to solve the above problems and improve the digestion resistance of magnesia fine powder and the workability of a magnesia-containing amorphous refractory, When magnesia fine powder is mixed with alumina fine powder and mechanical external force such as grinding force and impact force is applied to the mixture, alumina fine powder (child particles) is combined on the surface of magnesia fine powder (mother particle). It can be solidified (fixed), and can suppress the hydration reaction by the action of this alumina fine powder, and when it is added to the refractory aggregate, it prevents the rapid aggregation of castables after hydration. As a result, it was discovered that pouring could be possible without impairing its liquidity.

That is, according to the present invention, modified magnesia fine powder for amorphous refractories is obtained by directly fixing alumina fine powder on the surface of magnesia fine powder in a dispersed state by applying a mechanical external force according to the mechanochemical reforming method. Is. In the modified magnesia fine powder, the particle size of the magnesia fine powder is 1 to 20 μm, preferably 1 to 10 μm, while the particle size of the alumina fine powder is 0.01 to 4 μm, preferably 0.01 to 2 μm.
The size of m is preferable.

Further, the present invention provides an amorphous refractory using the above-mentioned alumina-modified magnesia fine powder, that is, an irregular refractory obtained by containing magnesia fine powder in a skeleton component. Proposing a magnesia-containing amorphous refractory characterized by containing 4 to 40 wt%, preferably 5 to 25 wt%, of alumina-modified magnesia fine powder obtained by directly adhering alumina fine powder to the surface thereof. Is.

[0008]

The modified magnesia fine powder in the present invention is a mixture of magnesia fine powder and alumina fine powder, and alumina fine powder which is a child particle is adhered to the outer surface of the magnesia fine powder which is a mother particle, preferably in a uniformly dispersed state, Next, the composite powder is subjected to impact force, grinding force,
It can be obtained by mechanically and firmly bonding the base particles so that they are inserted into the surface of the base particles while applying a mechanical external force such as a shearing force. As a device used in this mechanochemical reforming method, a mixer that can apply strong impact force, grinding force, and shearing force to particles, such as Ongmill (manufactured by Hosokawa Micron), hybridization system (manufactured by Nara Kikai) ), Hi-X (manufactured by Nisshin Seifun Co., Ltd.) and Henschel mixer (manufactured by Mitsui Miike Machinery) are suitable.

In the present invention, the mixing ratio of the magnesia fine powder (mother particles) and the alumina fine powder (child particles) shown by the weight percentage is preferably in the range of 99: 1 to 50:50. In this range, when the ratio of magnesia fine powder exceeds 99, the amount of alumina fine powder to be fixed is insufficient and the surface modification effect cannot be obtained. On the other hand, the ratio of this magnesia fine powder is 50
If less than, in addition to the alumina fine powder that contributes to surface modification,
This is because the amount of free alumina fine powder increases, which is uneconomical, and the original effect of magnesia is diminished.

The particle size of magnesia fine powder is 1 to 20 μm.
Use a size of m. The particle size of this fine powder is 1 μm
If it is less than 20 μm, the reaction with alumina will be incomplete, whereas if it is less than 20 μm, the coating will not be well covered. The preferred range of this particle size is 1-10
μm. On the other hand, as alumina fine powder, 0.01-4 μm
Use the one. The reason for this is that the fine alumina powder is 0.01 μm.
If it is smaller than 4 μm, the magnesia coating effect becomes insufficient, and if it exceeds 4 μm, the adhesion is deteriorated and the modifying effect becomes thin. The preferable particle size of the alumina fine powder is 0.01 to 2 μm.

Next, a magnesia-containing amorphous refractory material according to the present invention containing the above-mentioned alumina-coated modified magnesia fine powder will be described. First, as the aggregate constituting the skeletal component of the amorphous refractory, one or more selected from basic, neutral and acidic ones are used. For example, magnesia, spinel, alumina, zirconia,
Examples include zircon, silica, silica, pyrophyllite, silicon carbide, chamotte, and graphite. It is preferable to use the aggregate particle sizes that are separately adjusted for coarse particles, medium particles, fine particles, and fine powder so that a densely packed structure can be obtained.

The amount of the alumina-modified magnesia fine powder to be blended with the aggregate and the like in this amorphous refractory is in the range of 4 to 40 wt%. This is because if the content is less than 4 wt%, the spinel that contributes to slag penetration prevention and strength improvement will be insufficient in the matrix, while if it exceeds 40 wt%, excessive sintering will occur and cracks will occur frequently. Because it will be. The preferred range is 5 to 25 wt%
Is.

As an auxiliary agent which is optionally used in the amorphous refractory material according to the present invention, for example, as a curing agent, alumina cement, silica sol or alumina sol generally used for refractory materials is used. , As a dispersant, sodium tripolyphosphate, sodium hexametaphosphate, sodium ultrapolyphosphate, sodium acid hexametaphosphate, sodium borate, sodium carbonate, etc., inorganic salts such as sodium citrate, tartrate, sodium polyacrylate, sodium sulfonate and It is preferable to use any one kind or two or more kinds selected from sodium naphthalenesulfonate, and to use oxalic acid, citric acid, gluconic acid, boric acid as the curing retarder.

The amorphous refractory material according to the present invention may be any known fiber, metal powder, antioxidant, binder, etc. in addition to the above-mentioned compounds, as long as the effects of the present invention are not impaired. May be added.

[0015]

【Example】

Example 1 An experiment was conducted on the effect of the modified magnesia fine powder used in the present invention on the digestibility. In this experiment, the digestibility was evaluated by the weight increase rate (Gakushin method) in an autoclave at 120 ° C and 3 atm x 3 hr. The results are summarized in Table 1, and it can be seen that the modified magnesia fine powder is far more excellent in digestion resistance than the untreated magnesia fine powder. The modified magnesia fine powder used in this experiment was Hosokawa Micron Ong Mill AM-15F according to the mechanochemical reforming method. Magnesia fine powder and alumina fine powder were put into this Ong mill and subjected to modification treatment for 0.5 hour. It is a thing. By this treatment, there was obtained a magnesia fine powder having a size of 1 to 20 .mu.m, on the surface of which alumina having a size of 0.01 to 4 .mu.m was fixed in a dispersed state.

[0016]

[Table 1]

Example 2 This example was used as a castable for ironmaking (for blast furnace downdraft) in order to test the effect of the amorphous refractory mixed with the modified magnesia fine powder used in Example 1. The results are summarized in Table 2. In the case of Inventive Example 1 and Comparative Examples 1 and 2, the castables of Inventive Example 1 are denser and have higher strength than Comparative Example 1 (conventional material). On the other hand, in the example of Comparative Example 2 in which the magnesia fine powder which was not subjected to the modification treatment was used, the fluidity was not obtained and the crack was generated due to digestion, and the normal test piece could not be produced. When the amorphous refractory material (castable) according to the present invention was used in an actual machine, the service life was extended to 20 days compared to the conventional 14 days. Inventive Example 2 and Comparative Example 3 are examples when applied to castables for molten steel parts, and in the inventive example, the durability was improved to 350 charges as compared with the conventional 300 charges. Example 3 of the present invention is a castable for lining a converter brick and has a durability of 6000 charges per furnace.

[0018]

[Table 2]

[0019]

As described above, the modified magnesia fine powder according to the present invention is excellent in digestion resistance, and if it is blended in an irregular shaped refractory, the fluidity can be improved. The workability at the time is remarkably improved.

Front Page Continuation (72) Inventor Keiichiro Isomura 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Steel Research Laboratory, Kawasaki Steel Co., Ltd. (72) Masato Kumagai 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Kawasaki Steel Co., Ltd. Inside the Steel Research Institute (72) Inventor Kyonobu Toriya 1576, Higashioki, Ako-shi, Hyogo Prefecture, No. 2 at 1576, Kawasaki Furnace Material Co., Ltd. (72) Inventor, Junichiro Mori 1576, Higashioki, Ako-shi, Hokugo, Japan No. 2 inside Kawasaki Furnace Co., Ltd. (72) Inventor Katsumi Shirono No. 2 at 1576 East Offshore, Nakahiro, Ako City, Hyogo Prefecture

Claims (3)

[Claims] 1. A modified magnesia fine powder for amorphous refractories, which is obtained by directly adhering alumina fine powder to the surface of magnesia fine powder. 2. The average particle size of the magnesia fine powder is 1 to 2.
The modified magnesia fine powder according to claim 1, wherein the fine alumina powder has an average particle size of 0 to 4 µm and an average particle diameter of 0.01 to 4 µm. 3. An amorphous refractory having a skeletal component containing fine magnesia powder, and as the magnesia fine powder, an alumina-modified magnesia fine powder obtained by directly adhering alumina fine powder to the surface thereof is used. An amorphous refractory material containing magnesia, characterized in that the refractory material contains -40% by weight.