JPH066514B2 - Unshaped refractories for blast furnace cast bed desiliconization gutter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refractory composition for lining a blast furnace cast bed desiliconization gutter using a pretreatment facility for hot metal such as desiliconization, and particularly using an iron oxide type treating agent. .

[Conventional technology]

Currently, pretreatment such as desiliconization of hot metal is carried out in a gutter, a mixed pig wheel or a hot metal ladle. In recent years, the conditions for this pretreatment have become more severe due to the increased demand for high-grade steels, resulting in increased damage to the lining refractory materials used in these facilities, and the development of refractory materials having high durability has been desired.

As a refractory for hot metal pretreatment, due to its excellent corrosion resistance and spalling resistance, Al ₂ O ₃ : 20 to 80 wt%, Si
C: 5 to 20% by weight, C: 0 to 10% by weight of Al ₂ O ₃ -S
iC-C type refractory material is used.

However, in the hot metal pretreatment using iron oxides such as FeO and Fe ₂ O ₃ as a treating agent, particularly in the desiliconization in the blast furnace tap pipe, the molten slag is rich in FeO and the erosion of the gutter material becomes large.

Under this condition, the conventional Al ₂ O ₃ —SiC is used.
SiC and C in the -C refractory material are easily oxidized by FeO by the reaction shown in the following formula.

SiC + 3FeO → 3Fe + SiO ₂ + CO C + FeO → Fe + CO Therefore, in order to improve the corrosion resistance of the refractory material used in the hot metal pretreatment equipment, it has been attempted to adopt a means for increasing the reaction resistance with molten slag.

For example, Japanese Examined Patent Publication (Kokoku) No. 60-33782 proposes low SiC and low C to reduce the reactivity with FeO, and the content of SiC is said to be 5 to 20% by weight. In addition, as a refractory for hot metal pretreatment, the content of SiC is specified, and JP-A-61-99641 discloses that the content is 10 to 15% by weight, and JP-A-62-19961. In 143880, 12 to 18% by weight is described as an appropriate amount.

Furthermore, JP-A-63-117975 discloses that, in addition to limiting the content of SiC, strengthening the material by adding an antioxidant.

Further, in JP-A-63-17265, in order to eliminate the problem of oxidation of SiC and C by FeO, SiO,
An Al ₂ O ₃ —MgO-based material in which C is excluded and MgO is added has been proposed.

[Problems to be Solved by the Invention]

However, in the conventional low-SiC and low-C Al ₂ O ₃ —SiC—C materials, when the processing conditions are severe, the corrosion is accelerated and the durability is not sufficient.

In addition, the Al ₂ O ₃ —MgO-based material does not sufficiently suppress the infiltration of slag when used for a long time, is inferior in spalling resistance, and cannot obtain stable durability.

Therefore, the problem to be solved in the present invention is a hot metal pretreatment for a hot metal pretreatment facility having stable durability, particularly an amorphous fireproof material, in order to obtain a hot metal pretreatment using a treatment agent containing a pig iron oxide. The purpose is to infer the damage mechanism of refractory materials in the above from the samples after using the actual furnace, to deny the damage mechanism that has been proposed in the past, and to provide a high corrosion resistant refractory material from a new finding.

[Means for Solving the Problems]

The present invention, in an amorphous refractory composition for lining a hot metal pretreatment facility using an iron oxide-based treating agent, contains 55 to 90% by weight of silicon carbide, the balance is blended with other refractory materials and binders. It is an amorphous refractory for blast furnace cast bed desiliconization gutter characterized by

[Action]

In the conventional Al ₂ O ₃ —SiC—C refractory material whose corrosion resistance is improved to lower the SiC and C content, good service life is not always obtained in the actual furnace. In addition, it is considered that the conventional erosion test method does not correlate with the actual results of the actual furnace, for example, although a large amount of Fe is observed on the operating surface in the sample after using the actual furnace, it is not observed in the conventional erosion test.

The existence of such Fe is not confirmed in the conventional erosion test, probably because the test atmosphere and stirring conditions are different from those in the actual furnace.

As a result of various examinations by the present inventors on various test methods exhibiting an erosion pattern similar to the state after use in an actual furnace, it was found that the crucible erosion test shown in FIG. 1 reproduces a state very close to that in an actual furnace. .

According to the crucible erosion test, the relationship between the amount of SiC in the material and the erosion property tends to be reversed from that in the conventional test method, that is, the more SiC, the better the corrosion resistance.

It is considered that this is because the use of a large amount of SiC promotes the reduction of FeO in the treatment agent, forms a continuous Fe layer on the operating surface, and suppresses slug attack. In a material having a low SiC content, which has been considered to be good in the past, reduction of FeO is not sufficient and a continuous Fe coating layer is not formed, so that erosion progresses.

SiC and C have the same effect of forming the Fe coating layer, but if C is added in a large amount, the added water content of the amorphous refractory increases and the durability deteriorates due to the deterioration of the structure.
A material containing a large amount of SiC is preferable.

As the SiC used in the present invention, one having a purity of 95% or more is usually used, but a SiC having a purity of 80% or more can be used. If it is less than that, the water content for construction is increased, and the structure is deteriorated and the corrosion resistance is deteriorated.

The reason why the SiC amount is regulated to 55 to 90% by weight is that if it is less than 55% by weight, it is inadequate for forming the Fe coating layer and thus the corrosion resistance is poor. This is because the binder and the like, which are indispensable to the casting material or the stamp material, need to be added, so that the material cannot be practically manufactured.

There are no particular restrictions on the balance of the mixture, but as the main raw material, alumina-based raw materials such as fused alumina, sintered alumina, bauxite, and shale, or chamotte raw materials, spinel raw materials, and further zircon, zirconia, etc. Can be used, and carbon materials such as coal-based pitch, petroleum-based pitch, phosphorous graphite, artificial graphite, earth-like graphite, coal-based coke, petroleum-based coke and the like are generally used as an auxiliary material.

As the binder, alumina cement, ultrafine silica, clay, metallic aluminum powder can be used, and other dispersants can also be used.

〔Example〕

Erosion test of silicon carbide (SiC) -added material by two methods, new test method (test condition 1: FIG. 1) and conventional test method (test condition 2: FIG. 2) for evaluating the effect of metal Fe coating. I went.

The results are shown in Table 1.

Erosion test conditions 1. (Crucible erosion test) A 30φ × 35mm hole is made in a sample of 65 × 65 × 65mm, and an erosion agent is put in it.

Erosion agent Desiliconizing agent (FeO: 65 wt%, Fe ₂ O ₃ : 30
Weight%) Erosion temperature 1500 ℃ × 1hrs × 5cycles Test method Put an erosion agent in the above sample and heat it in an electric furnace at a specified temperature. After the test, measure the erosion area of the sample cross section.
(The erosion index is expressed as an index with sample No. 4 as 100, and the smaller the value, the smaller the erosion amount.) Erosion test condition 2. (Rotation erosion test) Erosion agent Desiliconizer (FeO: 65 % By weight, Fe ₂ O ₃ : 30
(% By weight) Erosion temperature 1500 ° C. × 30 min × 10 cycles Erosion test As shown in FIG. 2, a sample is lined on a rotating drum, and a burner is used to bring the erosion agent to a predetermined temperature, and the erosion agent is eroded at the above erosion temperature. After the test, the amount of erosion on the cross section of the sample is measured.

The erosion index is expressed as an index with sample No. 4 as 100, and the smaller the value, the smaller the erosion amount.

When the sample No. 7 of the present invention was lined in the desiliconization inclined trough, the corrosion resistance was better than that of the low SiC material of the sample No. 2 of the conventional product, and the amount of smelting reached 50,000 to 100,000 tons.

Further, it was confirmed from the sample after use of the product of the present invention that metal Fe coats the working surface of the refractory, blocks the supply of FeO, and suppresses erosion, as compared with the conventional product.

[Effects of the Invention] The amorphous refractory material of the present invention has the following effects.

(1) Corrosion resistance and spalling resistance are excellent and durability is increased even in an atmosphere using various types of pig-oxide treatment agents at high temperature.

(2) Since there is basically no need to change the preparation of the conventional lining material, the conventional equipment can be used as it is.

[Brief description of drawings]

Each of the attached drawings is a diagram showing a test method for the refractory material of the present invention. FIG. 1 shows a crucible test, and FIG. 2 shows a rotary erosion test.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takeki Yoshitomi 1-1, Higashihama-cho, Hachimansai-ku, Kitakyushu, Fukuoka Kurosaki Ceramics Co., Ltd. Shares In-house at Kimitsu Works (72) Inventor Akira Kojima No. 1 Kimitsu in Kimitsu City, Chiba Shin Nippon Steel Co., Ltd. Inside Kimitsu Works in Kai-sha

Claims (1)

[Claims] 1. A refractory composition for lining a hot metal pretreatment facility using an iron oxide type treating agent, wherein silicon carbide is 55
Amorphous refractory for blast furnace cast bed desiliconization gutter, characterized by containing ~ 90% by weight, the balance being mixed with other refractory materials and binders.