JPH0222167A - Unburned refractory material for hot metal vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a non-fired iron mixer for use in hot metal containers such as hot metal mixing cars, hot metal pots, etc., which perform hot metal pretreatment such as desiliconization, dephosphorization, and desulfurization at the same time as transporting hot metal. It concerns refractories.

[Conventional technology] Roastish or chamotite refractories have traditionally been used as refractories for hot metal containers such as pig iron mixers and hot metal pots, but with recent advances in steelmaking technology, A hot metal pot is not only used as a container between a blast furnace and a converter.
It also serves as a refining vessel for hot metal pretreatment such as desiliconization, dephosphorization, and desulfurization, and due to the rise in hot metal temperature and the effects of activated slag, conventional lowite or chamotite refractories are significantly affected. It was starting to show signs of wear and tear.

Therefore, in order to improve the durability of lowite-based refractories, lowite-silicon carbide refractories containing silicon carbide and alumina-silicon carbide-carbonized refractories using carbon materials were used instead.

[Problem to be solved by the invention] However, when the hot metal treatment rate increases, low stone/silicon carbide refractories do not have sufficient durability, while alumina/silicon carbide/carbon refractories have high corrosion resistance. Because the residual expansion coefficient is small, the joints may open during use and bare metal may intrude, and because carbon materials are used, the bricks in contact with the joints may be oxidized by oxygen in the air or Fen in the mill scale, leading to the joints opening. There is a drawback that peeling damage occurs due to cracks occurring due to repeated heating and cooling of the semicylindrical protrusions produced as a result of melting damage.

[Means for Solving the Problems] As a result of various studies in order to solve the above-mentioned conventional drawbacks in refractories for hot metal containers, the present inventors have found that the coefficient of thermal expansion and Focusing on the large coefficient of residual linear expansion, we developed alumina/silicon carbide/carbon by using alumina/carbon material or a material with silicon carbide added thereto and high thermal expansion silica or silica/alumina raw material. To solve the problem of joint opening in quality refractories, and to limit the particle size range in which silica or silica-alumina raw materials are used, since the use of silica or silica-alumina raw materials reduces corrosion resistance against slag. This invention was completed by successfully achieving corrosion resistance close to that of alumina, silicon carbide, and carbonaceous refractories.

That is, the present invention provides a refractory for use as a container for pre-treatment of hot metal such as desiliconization or as a container for transporting hot metal, which has high thermal expansion and high residual expansion and contains 80% by weight or more of grains with a particle size of 60 μm or more. 20-80% by weight of silica or silica-alumina raw material, 20-77% by weight of alumina raw material
, 3 to 30% by weight of carbon material or carbon material and silicon carbide
The feature of the present invention is that the particle size is 60
High thermal expansion and high residual expansion silica or silica-alumina raw material containing 80% by weight or more of particles of μm or more.
0 to 80% by weight, thereby achieving high thermal expansion and high residual expansion comparable to lowite/silicon carbide refractories, and durability comparable to alumina/silicon carbide/carbon refractories. It can be obtained at low cost.

Moreover, by adjusting the composition within the above range, the refractory of the present invention can balance thermal expansion, residual swelling property, and corrosion resistance, so combinations of the refractory of the present invention with different compositions Alternatively, the entire vessel can be lined with the refractory of the present invention, and the remaining parts can be lined with alumina, silicon carbide, or carbonaceous refractories for the slag line, or lined with alumina, silicon carbide, or carbonaceous refractory for the pig iron bath or furnace bottom. It is also possible to use conventionally known refractories such as stone/silicon carbide or low stone to balance the overall wear and tear of the container.

C action] The 5i02 component in the silica or silica/alumina raw material can be heated by using alumina/carbon material or a material with silicon carbide added thereto and high thermal expansion silica or silica/alumina raw material. This prevents the transformation of α-quartz to β-quartz and cristobalite, and also prevents brick joint opening due to high thermal expansion and high residual expandability due to broaching at high temperatures. Its high thermal expansion and high residual expansion can be increased as its usage increases. However, by using silica or silica-alumina raw materials, oxidation prevention and corrosion resistance can be improved by reducing the porosity of the bricks by vitrifying the SiO If the amount used is increased to increase the size, the corrosion resistance will gradually decrease. However, the part of the silica or silica-alumina raw material that is attacked by slag is first the fine powder part, and the coarse part is relatively difficult to be attacked by slag. Furthermore, in order to achieve high thermal expansion and high residual expansion, it is more effective to use silica or silica-alumina raw materials in coarse particles when the same amount is added. good.

The silica or silica/alumina raw materials with high thermal expansion and high residual expansion used in this invention are lowite, silica, etc., and have a thermal expansion coefficient of 1.5% or more at 1000°C and a residual linear expansion coefficient of 1400°C. It is desirable that the material exhibits 2% or more after heat treatment, and it is necessary that particles with a particle size of 60μ1 or more account for 80% by weight or more. When used in refractories, bricks show residual expansion when high thermal expansion silica or silica-alumina raw materials are used in the aggregate part, and when used in the fine powder part of 60 μm or less. Not only will the characteristics not be exhibited, but the corrosion resistance will be extremely reduced. Further, the amount used is 20 to 80% by weight, and if it is more than 80% by weight, the corrosion resistance will decrease, and if it is used less than 20% by weight, sufficient expansion characteristics will not be obtained and openings will occur. By using silica or silica-alumina raw materials with high thermal expansion and high residual engraving properties under the above conditions, the surface of the refractory in use can be integrated without any joints by engraving and vitrification using silica. , indicating a smooth, pore-free Ja@ state.

Alumina raw materials include fused alumina, sintered alumina,
Sillimanite, bauxite, etc. are used, and the content of 203 in the raw material is 70% by weight or more when used in pig iron mixers, especially in the slag line section, and 50% by weight or more in hot metal ladle for corrosion resistance. Desirable from this point of view. The amount of alumina raw material used is 20 to 75% by weight. If it is less than 20% by weight, corrosion resistance cannot be fully exhibited, and if it is more than 77% by weight, silica or silica-alumina raw materials will inevitably be heated. Since expandability and residual engraving properties cannot be obtained, joint openings occur and base metal intrusion occurs.

Carbon materials contribute to corrosion resistance due to their low wettability with slag, and spalling resistance due to their good thermal conductivity. Various carbonaceous materials can be used, but natural and artificial graphite are particularly preferred from the viewpoint of corrosion resistance. Crystalline ones are more preferable.

The oxidation resistance of silicon carbide is improved by using it. This silicon carbide has the effect of suppressing oxidation of the carbon material and making the carbon material exhibit high corrosion resistance and high spalling resistance.

The content of oxygen material or carbon material and silicon carbide used is 3 to 30% by weight. If it is less than 3% by weight, the corrosion resistance and spalling resistance will be poor, and if it is more than 30% by weight, the mechanical strength will decrease and the resistance will be poor. Becomes less abrasive.

A resin binder is added to the mixture containing the above raw materials and kneaded, followed by heat treatment after molding to obtain unfired bricks. The resin binder may be one that hardens by heat treatment, and is preferably a phenol resin, although it is not particularly limited.The amount added is usually 1.5 to 10% by weight; The amount to be added is 40-50% of the amount added.
That's about it. In addition to the above-mentioned materials, it is also possible to add metal powder for the purpose of improving oxidation resistance.

[Example] The formulations shown in Table 1 were molded using a friction press, and the molded products were heat-treated at 300° C. for 10 hours to obtain unfired bricks. Its physical properties and various test results are also shown in Table 1.

In addition, the coefficient of thermal expansion of the raw stones used was 2.2% at 1000°C, and the coefficient of residual linear expansion after heat treatment at 1400°C was 4.8.
%, and silica has a thermal expansion coefficient of 1.8% and a residual linear expansion coefficient of 3.
It was 5%.

Slag test is 1400-14 by rotary slag test method.
The test was carried out at 50°C for 3 hours. Slag composition is FeO48% by weight
, 42% by weight of CaO, and 212% by weight of CaF were used. The erosion index was expressed as a ratio with Comparative Example 1 being 100.

[Effects of the Invention] As is clear from the results in Table 1, the refractory of the present invention using highly thermally expandable silica or silica-alumina raw materials in the aggregate portion has a low thermal expansion coefficient and residual line while suppressing erosion loss. It can be seen that the fat swelling ratio is high and that it is effective in suppressing joint opening.

Areas where high thermal expansion silica or silica-alumina raw materials such as lowite and silica stone used are as low as 25% by weight (
In Examples 1 to 4), the erosion loss in the slag is somewhat lower than that of the alumina/silicon carbide/carbonaceous material (Comparative Example 1), but the thermal expansion coefficient and residual linear fat expansion coefficient are large. There is no joint opening or spalling, and the durability is the same or longer.

In addition, the amount of raw stone and silica stone used was 50% by weight (Example 5
~7) to 75% by weight (Example 8), the increase in the coefficient of thermal expansion and the coefficient of residual linear fat expansion becomes more remarkable, but the melting loss gradually increases.

Comparative Example 1 is made of alumina/silicon carbide/carbon and has good corrosion resistance, but has a low coefficient of thermal expansion and a low coefficient of residual linear fat expansion, and suffers from large damage due to joint opening. Comparative Example 2 is made by adding silicon carbide and a carbonaceous material to lowite, and has a sufficient coefficient of thermal expansion and coefficient of residual linear fat expansion, but is poor in corrosion resistance against slag. Furthermore, in Comparative Example 3, the amount of loite used was less than the range of the present invention, and the values of the coefficient of thermal expansion and the coefficient of residual linear fat expansion were insufficient.

Furthermore, although Comparative Examples 4 to 9 are all within the scope of the present invention in terms of composition, they are not compatible because the silica or silica/alumina material with a particle size of 60 Pm or more is 80% by weight or less and has a large amount of fine powder. The thermal properties were only slightly smaller than the corresponding examples (Example 3 and Comparative Examples 4 and 5, Examples 6 and 7 and Comparative Examples 6 to 8, and Example 8 and Comparative Example 9). However, the corrosion resistance deteriorates significantly.

In a hot metal container, the degree of joint opening and melting damage differs depending on the part where it is used.In the slag line part, the melting loss is large but the degree of joint opening is small, and in the iron bath or furnace bottom, the joint opening is less likely to occur due to the influence of heat load. Although the extent of the damage increases, especially at the bottom of the furnace, the erosion caused by slag is reduced. Therefore, by adjusting the amount added within the composition range of the present invention depending on the use area such as the slag line, pig iron bath, or furnace bottom of the hot metal container, it is possible to balance the melting loss of the entire container. That is, the refractories of Examples 1 to 4, especially Examples 2 to 4, are effective when used in the slag line, Examples 6 to 8 are effective when used in the iron bath or furnace bottom, and especially Example 8 is effective when used in the furnace bottom. be. In this case, the entire container may be lined with a combination of the refractories of the present invention, or the refractory of the present invention may be partially lined in the above application example, and the remaining portion may be lined with alumina, silicon carbide, or carbon if the slag line is used. It is also possible to use refractories such as low stone, silicon carbide, or low stone for the pig iron bath and furnace bottom.

4 others

Claims (1)

[Claims] 1 High thermal expansion and high residual expansion silica or 20 to 80 weight % of alumina raw material containing 80 weight % or more of particles with a particle size of 60 μm or more, 20 to 77 weight % of alumina raw material, carbon material or carbon material An unfired refractory for hot metal containers, characterized by comprising 3 to 30% by weight of carbon silicon and a resin binder.