JP2787951B2 - Mud material for blast furnace taphole - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tapping mud material for a blast furnace.

[Conventional technology]

In recent years, the steel industry has concentrated on a small number of large blast furnaces, and efforts have been made to increase the tapping ratio [t-pigiron / sunshine volume (m ³ )]. Blast furnaces with 2.0 or more are increasing.

If the blowing rate is increased to increase the tapping ratio, the outflow speed of tapping slag increases, and the taphole mud material is greatly damaged, resulting in a decrease in tapping time. In addition, in the high tapping ratio operation, if the opening diameter is small, the tapping speed is too low in the early stage of tapping, compared to the tapping speed, and the level of the tappings in the furnace increases, causing fluctuations in the furnace pressure. Adversely affect operations. Therefore, it is necessary to increase the opening diameter, but when the opening diameter is increased, the tapping time is reduced.

Conventional blast furnace taphole mud materials used include refractory aggregates such as pyroxene, chamotte, alumina, silicon carbide, and carbon, refractory clays, sintering agents such as metallic silicon, and binders such as tar. I have.

[Problems to be solved by the invention]

The above-mentioned silicon carbide and carbon are added in a considerable amount in order to increase the corrosion resistance and wear resistance. However, since these substances do not have self-sintering properties, the strength decreases with an increase in the addition amount. Therefore, in order to prevent such a decrease in strength, a large amount of clay is added. The clay reacts with the blast furnace slag to generate a low melt. Therefore, the tapping hole diameter rapidly increases with the outflow of blast furnace slag, and the tapping ends with the molten iron and slag remaining in the furnace, leading to an increase in the number of tappings and an increase in labor load. Was. In order to solve this problem, attempts have conventionally been made to reduce the amount of clay and to use alumina fine powder, zircon fine powder and the like.

However, alumina, zircon, and the like cannot obtain sintering properties comparable to those of clay, and there is a disadvantage that the diameter of the pores increases in the initial stage of tapping when used in an actual furnace.

The present invention has been proposed in view of the above-described conventional circumstances, and has a high corrosion resistance to hot metal and slag, has a large strength, and a mud material having no rapid expansion phenomenon of a tap hole. The purpose is to provide.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an SiO ₂ content of 75
Up to 90% of high silica silicate is used as the main raw material, and the particle size is 44μ.
0.5 to 4 parts by weight of graphite having a particle size of 0.5 m or less, 15 to 30 parts by weight of silicon nitride having a particle size of 44 μm or less, 5 to 15 parts by weight of kaolin clay, and the rest of other refractory materials such as silicon carbide and coke. A non-oxide is used, and a residual carbon organic compound is added and kneaded as a binder such as tar. In addition, the weight part of the high silicate fossilite having a SiO ₂ content of 75 to 90% or more used as the main raw material and the remaining other refractory material is 51 to 79.5 parts by weight.

(Operation)

Silicon nitride number to be used in the present invention is obtained by nitriding ferrosilicon, containing Si ₃ N ₄ 70~80%, most remaining a metal Fe and FeSi. Among them, Si ₃ N ₄ has a covalent bond property and inherently has high oxidation resistance, and has a property that it is difficult to get wet with hot metal and molten slag.
It has the property of gradually decomposing at a temperature of ℃ or more and releasing nitrogen. It is presumed that this nitrogen reacts with kaolin clay in the presence of carbon and is fixed in the refractory, thereby improving the densification and corrosion resistance of the mud material.

That is, kaolin clay reacts with nitrogen in the presence of carbon as shown in the following formula (1) to produce sialon.

The sialon generated by the above reaction is hardly wetted by molten iron and molten slag, and has no property of reacting with molten slag, which is a drawback of clay, to produce a low-melting substance, thereby greatly improving the corrosion resistance of the mud material.

The fine powder of silicon nitride having a diameter of 44 μm or less easily reacts with the clay, and its addition amount is suitably 15 to 30 parts by weight in the mud material. If the amount is less than 15 parts by weight, the volatilization of nitrogen is small, and the reaction between the clay and nitrogen cannot sufficiently occur. If the amount is more than 30 parts by weight, the reaction sintering strength becomes too high, and it is difficult to form holes. If the particle size of the silicon iron nitride is 44 μm or more, the reaction with the clay is poor, and the clay remains unreacted, so that the corrosion resistance is reduced.

The main aggregate, SiO ₂ content of 75 to 90 percent more high silica pyrophyllite react with blast-furnace slag is gradually damage resulting highly viscous melt is suitable. If the SiO ₂ content is less than 75%, the viscosity of the melt becomes too low, resulting in increased wear. 90% SiO ₂ content
If the amount is larger than that, sintering becomes insufficient, and the strength decreases.

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 compounding ratio is suitably 0.5 to 4 parts by weight. If it is less than 0.5 part by weight, a sufficient reaction with nitrogen cannot be obtained, and if it is more than 4 parts by weight, sintering is hindered, which is inconvenient. The particle size of graphite is preferably 44 μm or less, and if it is 44 μm or more, the reaction between nitrogen and clay is poor, and the clay remains unreacted, so that the corrosion resistance is reduced.

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, the amount of unreacted clay becomes too large, adversely affecting the corrosion resistance of the mat material.

In addition, non-oxide raw materials such as silicon carbide and coke, and additives such as metal silicon, ferrosilicon, and aluminum powder can be used as necessary as the remaining refractory materials. As the binder, a residual carbon organic compound, for example, commonly used tar, tar pitch, or phenol resin can be used.

With the above configuration and action, the mud material of the present invention exhibits good corrosion resistance and sufficient strength near the operating temperature,
In addition, since low-melting-point substances are not generated at the time of tapping, rapid expansion of tap holes during low tapping ratio operation is eliminated.

〔Example〕

Hereinafter, the present invention will be further clarified by giving Examples and Comparative Examples.

Table 1 shows the compounding ratio and hot bending strength (1400) of Examples (a) and (b) of the present invention and Comparative product (c) according to the conventional production method.
C.) and its corrosion resistance. As can be understood from Table 1, the product of the present invention has a hot bending strength,
It can be understood that the corrosion resistance is far superior to the comparative example of the conventional product.

When the mud material of the present invention was used in a blast furnace, the expansion of the hole diameter during tapping was small, and the tapping time was about 1.5 times longer than before, thereby reducing the amount of mud material used and the labor load.

[Effect of the Invention] As described above, the present invention has a SiO ₂ content of 75 to 90.
% Of high-silicate fossilite as the main raw material, the particle size is 44μm in the fine powder part
By combining the following silicon iron nitride with graphite and clay having a particle size of 44 μm or less, the corrosion resistance and strength in the operating temperature range are sufficient, and there is an advantage that the taphole does not rapidly expand in a blast furnace.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sadayuki Yamazaki 1576, Nakahirohiro Higashi-oki, Ako City, Hyogo Prefecture 2 Kawasaki Furnace Materials Co., Ltd. No. 2 in Kawasaki Furnace Materials Co., Ltd. (72) Inventor Tatsuo Kawakami 1576, Nakagiro-ji, Higashi-oki, Aki-shi, Hyogo No. 1576 2 in Kawasaki Furnace Materials Co., Ltd. Chome (without address) Mizushima Works, Kawasaki Steel Corporation (72) Inventor Yoshikazu Senoo 1-chome, Mizushima, Kawasaki-dori, Kurashiki City, Okayama Prefecture (without address number) Mizushima Works, Kawasaki Steel Corporation (58) Field surveyed (Int. Cl. ⁶ , DB name) C21B 7/12 C04B 35/16

Claims (1)

(57) [Claims] 1. 0.5 to 4 parts by weight of graphite having a particle size of 44 μm or less, 15 to 30 parts by weight of silicon iron nitride having a particle size of 44 μm or less, 5 to 15 parts by weight of kaolin clay, and SiO ₂ used as a main raw material. High silicate pyroxene with a content of 75-90% and the rest refractory 51-7
A mud material for a blast furnace taphole, wherein a residual carbon organic compound is added and kneaded as a binder to 9.5 parts by weight.