JPH02285015A - Mud material for tap hole of blast furnace - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance and strength of a mud material in the service temp. range by combining high-silica pagodite as a base with prescribed amts. of graphite, ferrosilicon nitride, kaolin clay, etc., each having a prescribed grain size7. CONSTITUTION:This mud material for the tap hole of a blast furnace is based on high-silica pagodite having 75-90% SiO2 content and is obtd. by combining this pagodite with 0.5-4 pts.wt. graphite of <=44mum grain size, 15-30 pts.wt. ferrosilicon nitride of <=44mum grain size, 5-15 pts.wt. kaolin clay and the balance refractory material such as silicon carbide or ferrosilicon. An org. compd. with residual carbon such as tar, tar pitch or phenol resin is added to the refractory material.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a mud material for a tap hole in a blast furnace.

Efforts to increase the furnace internal volume (d) are continuing, and the number of blast furnaces with an iron tap ratio of 2.0 or higher is increasing.

In order to increase the tap ratio, when the air flow rate is increased, the flow rate of the tap slag increases, which causes significant damage to the tap hole mud material and reduces the tap time. In addition, in high-output ratio operations, if the opening diameter is small, the tapping slag rate is too low compared to the pig iron making rate at the early stage of tapping, and the level of stored pig iron in the furnace becomes high, causing fluctuations in the furnace pressure. , adversely affecting operations. Therefore, it is necessary to increase the opening diameter, but increasing the opening diameter causes a reduction in the tapping time.

Conventional mud materials for blast furnace tapholes include refractory aggregates such as waxite, chamotte, alumina, silicon carbide, and carbon, sintering agents such as fireclay, metal silicon, and binders such as tar. There is.

[Conventional technology]

In recent years, the steel industry has been concentrating on large-scale blast furnaces with a small number of units, and the pig iron production ratio [daily iron production (t-pigiron) / [
Problems to be Solved by the Invention] As mentioned above, silicon carbide and carbon are added in considerable amounts to increase corrosion resistance and wear resistance, but since these substances do not have self-sintering properties, it is difficult to increase the amount added. The strength decreases accordingly. Therefore, in order to prevent such a decrease in strength, a large amount of clay is added, but this clay reacts with the blast furnace slag to produce low-melting substances. Therefore, as the blast furnace slag flows out, the diameter of the tap hole rapidly expands, and the tapping ends with hot metal and slag remaining in the furnace, leading to an increase in the number of times of tapping and an increase in labor load. Ta.

In order to solve this problem, attempts have been made to reduce the amount of clay, use fine alumina powder, fine zircon powder, etc.

However, with alumina, zircon, etc., the sinterability of the amount of clay cannot be obtained, and there is a drawback that the pore diameter expands greatly at the initial stage of tapping when the furnace is used.

This invention has been proposed in view of the above-mentioned conventional circumstances, and provides a mud material that has high corrosion resistance against hot metal and slag, has great strength, and does not cause rapid expansion of the tap hole. The purpose is to provide.

[Means to solve the problem]

In order to achieve the above object, the present invention provides SiO2-containing M
Containing -75 to 90% acid oxalite is used as the main raw material, and graphite with a particle size of 44 μm or less is added to 0. 5 to 4 parts by weight and particle size 44
15 to 30 parts by weight of iron silicon nitride of micrometer or less, 5 to 15 parts by weight of kaolin clay, and the rest non-oxides such as silicon carbide and coke are used as other refractory materials, and residual carbon organic compounds such as tar are added. I try to knead it.

[For production]

The iron silicon nitride used in this invention is nitrided ferrosilicon and contains 70 to 80% of Si and N4, with most of the remainder being metal Fe and Fs3i. Si and N among these have covalent properties and are inherently highly oxidation resistant, making them difficult to wet with hot metal and molten slag, but they gradually decompose at temperatures above 1400°C. It has the property of releasing nitrogen. It is presumed that this nitrogen reacts with kaolin clay in the presence of carbon and is fixed in the refractory, improving the densification and corrosion resistance of the mud material.

That is, kaolin clay has the above-mentioned (
As shown in equation 11, it reacts with nitrogen to produce sialon.

N, -*S t, N, ・A1. O, .AzN+ Sialon produced by the above reaction is difficult to get wet with hot metal and molten slag, and does not have the tendency of reacting with molten slag to produce low-melting substances, which is a disadvantage of clay, and greatly improves the corrosion resistance of the mantle material.

Fine powder of silicon iron nitride of 44 μm or less easily reacts with clay, and the appropriate amount to be added is 15 to 30 parts by weight in the mud material. If it is less than 15 parts by weight, the volatilization of nitrogen is small and the reaction between the clay and nitrogen cannot occur sufficiently. If it exceeds 30 parts by weight, the reaction sintering strength becomes too high, making it difficult to form holes, which is disadvantageous.

When the particle size of silicon iron nitride is 44 μm or more, the reaction with clay is poor and the clay remains unreacted, resulting in a decrease in corrosion resistance.

The main aggregate is suitably high silicate waxite with an S i 02 content of 75 to 90%, which reacts with blast furnace slag to form a highly viscous melt and is gradually damaged. If the SiO□ content is less than 75%, the viscosity of the melt decreases too much and wear increases. 5i
If the Ot content is more than 90%, sintering will be insufficient and the strength will decrease.

In the present invention, graphite having a particle size of 44 μm or less is used.

Graphite promotes the reaction between nitrogen and clay. The appropriate blending ratio is 0.5 to 4 parts by weight; if it is less than 0.5 parts by weight, sufficient reaction with nitrogen cannot be obtained, and if it is more than 4 parts by weight, sintering is inhibited, which is disadvantageous. The particle size of graphite is 44
The thickness is preferably .mu.m or less; if the thickness is 44 .mu.m or more, the reaction between nitrogen and clay is poor and the clay remains unreacted, resulting in a decrease in corrosion resistance.

If the kaolin clay is less than 5 parts by weight, the reaction with carbon and nitrogen is insufficient, and if it exceeds 15 parts by weight, there will be too much unreacted clay, which will adversely affect the corrosion resistance of the mud material.

In addition, as the remaining refractory material, non-oxide raw materials such as silicon carbide and coke, additives such as metallic silicon, ferrosilicon, and aluminum powder, etc. can be used as necessary. As the binder, carbon-residue organic compounds such as commonly used tar, cool pitch, and phenol resin can be used.

Due to the above structure and function, the mud material of the present invention exhibits good corrosion resistance and sufficient strength near the operating temperature, and does not generate low melting point substances during tapping, so it Rapid expansion of the pig hole is eliminated.

(at 00°C), which shows the corrosion resistance.

As can be seen from Table 1, the products of the present invention are far superior in hot bending strength and corrosion resistance to the comparative examples of conventional products.

By using the mud material of the present invention in a blast furnace, there is less pore diameter expansion during tapping, and the tapping time is approximately 1.5 times longer than conventional methods, thereby reducing the amount of mud material used and labor load. did.

〔Example〕

EXAMPLES Hereinafter, examples and comparative examples will be given to make the present invention even clearer.

Table 1 shows the blending ratio and hot bending strength (14
Table 1 [Effects of the Invention] As explained above, this invention has SiO□ containing 175~
The main raw material is 90% high silicate waxite, and the fine powder part has a particle size of 4.
The combination of silicon iron nitride with a particle size of 4 μm or less and graphite and clay with a particle size of 44 μm or less provides sufficient corrosion resistance and strength in the operating temperature range, and has the advantage of not causing rapid expansion of the tap hole in a blast furnace.

Claims (1)

[Scope of Claims] [1] Highly silicate waxite with a SiO_2 content of 75 to 90% is used as the main raw material, and 0.5% of graphite with a particle size of 44 μm or less is used as the main raw material.
~4 parts by weight and 15 to 30 iron silicon nitride with a particle size of 44 μm or less
A mud material for a blast furnace taphole, characterized in that it is kneaded by adding and kneading parts by weight of kaolin clay, 5 to 15 parts by weight of other refractory materials, and residual carbon organic compounds.