JPH07115952B2 - Irregular shaped refractory for stainless hot metal ladle and stainless hot metal ladle lining it - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina silicon carbide / carbonaceous amorphous refractory suitable for lining a stainless hot metal ladle.

[0002]

2. Description of the Related Art Recently, as a refractory material for lining a ladle, an amorphous refractory material has been used from the viewpoint of resource saving and labor saving. In other words, instead of replacing all the worn refractory materials, repairing and repairing the refractory materials can be performed by adding and repairing the refractory materials so as to fill only the worn parts of the refractory materials. By changing to construction, the construction can be done with less manpower and heavy work can be eliminated.

In the case of a ladle for ordinary steel, zircon type amorphous refractory, alumina type irregular refractory, basic irregular type refractory, etc. are used, and basic irregular type refractory contains alumina spinel type refractory. Standard refractory materials are preferred.

However, in the case of a stainless hot metal ladle, the slag has a low basicity (usually low CaO content,
It refers to slag with a large amount of O ₂ component), and the melting points of slag and hot metal are low. For this reason, the viscosity of slag and molten pig iron during operation is low, and if you use an irregular refractory used for a ladle for ordinary steel, the slag permeates into the refractory and the refractory is altered, and the coefficient of thermal expansion is Since the structural spalling that changes and peels off the deteriorated layer of the refractory causes the structural spalling, the refractory has a short service life, and therefore, the regular refractory is still used at present.

At present, for example, an alumina silicon carbide carbon type regular refractory is used as a refractory lining for the stainless hot metal ladle. However, since this refractory is a standard refractory, it has the above-mentioned drawbacks.

On the other hand, the application of an alumina silicon carbide carbonaceous amorphous refractory to the hot metal part of the side wall of a blast furnace ladle for pretreatment of hot metal is described in Refractory Vol. 42, No. 11, page 648 (issued by the Refractory Society of Japan in 1990). Therefore, it is concluded that it is inferior in corrosion resistance to conventional refractories but can be sufficiently used.

[0007]

DISCLOSURE OF THE INVENTION The present invention is an amorphous silicon carbide-carbonaceous amorphous material which is suitable for a stainless hot metal ladle and which has a durability not inferior to that of a conventionally used standard refractory material. It is intended to provide refractory materials.

[0008]

The present invention has been made to solve the above-mentioned problems, and the stainless hot metal of the present invention is provided.
Amorphous refractory for ladle is weight% excluding added water
And silicon carbide (SiC) 1-20%, carbon 1-15%
%, 0.5 to 5% of alumina cement, 3 to 13% by weight of ultrafine powder of alumina and silica, and the balance being alumina aggregate.

In the amorphous refractory of the present invention, the inclusion of silicon carbide improves the thermal shock resistance, prevents the oxidation of carbon, prevents the penetration of slag having a low basicity into the refractory, and improves the refractory resistance. It is responsible for suppressing oversintering (shrinkage during use). If it is less than 1% by weight, the desired effect cannot be obtained. If it exceeds 20% by weight, silicon carbide is the FeO component in the slag. The problem that the corrosion resistance decreases due to the easy reaction with In order to obtain these effects, the content of the silicon carbide based aggregate is more preferably 4 to 10% by weight.

Further, carbon prevents penetration of slag,
It imparts the effect of improving the thermal shock resistance, and in order to obtain these effects, it is necessary to contain at least 1% by weight of carbon dioxide, and conversely, if it exceeds 15% by weight, Since it does not become a refractory having a dense structure, strength and erosion resistance decrease, which is not preferable. For the purpose of obtaining these effects, the carbon content is preferably 3 to 9% by weight.

The types of carbon used as raw materials are pitch,
Graphite electrode scraps, coke powder, carbon black, naturally occurring clay-like graphite, flake-like graphite and the like can be used, and it is more preferable to use graphite having good crystallinity from the viewpoint of oxidation resistance and corrosion resistance.

Alumina cement has a function as a binder of a refractory material, and in the amorphous refractory material of the present invention,
The inclusion of alumina cement is devised to reduce its content so as not to impair the corrosion resistance. That is, a normal alumina cement-bonded amorphous refractory has a low corrosion resistance because it contains 10% by weight or more of alumina cement, but the amorphous refractory of the present invention has an alumina cement content of 5% by weight or less ( By adjusting the CaO content to 2% by weight or less) and by using a dense refractory structure, corrosion resistance comparable to that of the conventional standard refractories is obtained.

If the content of the alumina cement is less than 0.5% by weight, the strength of the refractory material near the normal temperature becomes small, which is not preferable. The content of alumina cement is more preferably 1 to 4% by weight from the viewpoint of securing the effect as a binder and maintaining good corrosion resistance.

By containing the ultrafine powder, the amount of water required for casting the amorphous refractory can be reduced, the refractory having a fine structure can be obtained, and the content of alumina cement can be reduced. Even so, it has an effect of obtaining a refractory material having high strength, and this effect is further improved by incorporating ultrafine powder of alumina and silica.

If the content of the ultrafine powder is less than 3% by weight, these effects cannot be sufficiently obtained, and if it is more than 13% by weight, when the refractory is used at high temperature, the oversintering phenomenon occurs in the refractory and the fireproofing occurs. It is not preferable because cracks are likely to occur in the product. The content of ultrafine powder in the refractory is more preferably 7 from these viewpoints.
~ 12% by weight.

Clay powder (mainly composed of alumina and silica) can also be used as the ultrafine powder, and the proportion of alumina and silica in the ultrafine powder can be adjusted so as to increase the fire resistance. It is preferable that the content of the component is relatively higher than the content of silica.

Since the alumina-based aggregate is rich in resources,
It is an aggregate that can be obtained at a relatively low cost, has a high degree of fire resistance, and is suitable for the amorphous refractory material of the present invention, and usually contains 50 to 80% by weight. As the alumina-based aggregate, fused alumina, sintered alumina, synthetic mullite, calcined bauxite, calcined alum shale, etc. can be used.

The particle size of the alumina-based aggregate is 3 to 10 in order to secure thermal shock resistance and dimensional stability of the refractory.
It is preferable that the size of the aggregate is about mm, and since the aggregate has a small porosity to obtain a dense refractory, the aggregate is prepared by sieving into coarse particles, medium particles, and fine particles as is usually done. Is preferably used.

When water is added to an amorphous refractory and casting is performed, a dispersant is usually added to improve the flowability of the refractory, that is, the castability, even with a small amount of water. As the dispersant, at least one, preferably two or more organic dispersants such as inorganic salts such as sodium hexametaphosphate and a condensate of naphthalene sulfonic acid formalin are added in a total amount of 0.05 to 0.5% by weight (outer coat). ) Is preferably added.

The amorphous refractory of the present invention has the above-mentioned constitution, thereby breaking the conventional wisdom that the fixed refractory is superior in corrosion resistance, and the regular refractory of the same system which is being used conventionally. It is possible to obtain a product that is comparable in corrosion resistance to that of a standard product, and since there are no joints that are inferior in corrosion resistance as when a standard refractory is installed, the standard fire resistance is as high as there is no erosion from the joint in the installed state. Corrosion resistance will be better than when a product is constructed.

Thus, not only is the stainless hot metal ladle on which the irregular-shaped refractory of the present invention is applied has a good durability, but also when the refractory is exhausted, the refractory basic unit is replenished and repaired. It is significantly reduced, heavy work can be omitted even in the case of new construction, and the remarkable effect that this construction requires less manpower can be obtained. When adding and repairing, it is necessary to scrape off the slag adhering to the surface and scrape off the part of the refractory that is infiltrated with slag before constructing a joint, but the penetration of slag into the refractory This small amount facilitates this scraping work.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. As the aggregate which is a raw material of the refractory, calcined bauxite, sintered alumina, sintered magnesia, sintered spinel and silicon carbide classified into the particle size ranges shown in Table 1 and Table 2 were prepared.

Further, as carbon, earth graphite, graphite electrode scrap (artificial graphite) and flake graphite are used, and as ultrafine powder, silica having a particle size of about 0.5 μm, alumina having a particle size of about 0.5 μm and particle size are used. About 2 μm of clay was prepared.

Alumina cement manufactured by Asahi Glass Co., Ltd. (trade name: Asahi Alumina Cement) was added to these, and the results are shown in Tables 1 and 2.
In a mixed batch of the formulation shown in 1), water and a dispersant (sodium hexametaphosphate and formalin condensed sodium naphthalenesulfonate in a combined ratio of 1: 2 were used together) were added and mixed, and the internal volume was mixed. Is 40 mm x 40 mm x 16
Pour into a 0 mm mold with vibration, remove from mold 24 hours later, then dry at 110 ° C for 24 hours, size 4
A test refractory having a size of 0 mm × 40 mm × 160 mm and a weight of about 0.7 kg was obtained.

Further, the test refractory for trial production was heated at 1400 ° C. for 3 hours in a reducing atmosphere filled with coke.
Table 1 and Table 2 collectively show the mixing conditions of the test refractories for trial production. In Tables 1 and 2, Test Nos. 1 to 6 are Examples, and Test Nos. 7 to 10 are Comparative Examples. In addition, No.
No. 8 is a high-alumina, low-alumina cement-based amorphous refractory with low porosity, and No. 9 is an unfired regular refractory used for the lining of stainless hot metal ladle, No. 10
Is an alumina spinel amorphous refractory used for ordinary steel ladle.

The physical properties investigated for these refractories are shown in Table 3.
And summarized in Table 4. The evaluation of the corrosion resistance of the refractories shown in Tables 3 and 4 was carried out using a rotary erosion test furnace. That is, each refractory is 50 mm in the bottom, 100 mm in the bottom,
It has a cross section of an isosceles trapezoid with a hypotenuse of 100 mm, and is cast or processed into a seri brick with a depth of 200 mm, and these are combined into a hexagonal cylinder with an inside diameter of about 90 mm to form a steel plate cylindrical case with an inside diameter of about 350 mm. Put it in a box, fix it with MgO stamp material, and attach a perforated lid made of fired refractory to both ends of the hole with an inner diameter of about 90 mm, with this lid about 20 mm in height and about 20 mm in thickness
Ribs were formed into a furnace body for testing.

The furnace body is placed sideways and CaO is placed inside.
Approximately 500 g of stainless steel slag with a composition of 45% by weight, MgO 10% by weight, Al ₂ O ₃ 7% by weight, SiO ₂ 30% by weight, FeO and other 8% by weight, and a small piece of stainless steel pig with an outer diameter of 5 mm and a length of 50 mm. About 500 g and about 50 g of calcium fluoride as a flux were charged, a burner flame was blown from one side, and the inside of the furnace was heated and maintained at 1500 ° C. for 1 hour while rotating at a rotation speed of 10 RPM. After that, the furnace body was tilted, the molten slag and the stainless steel pigtail were poured out, and forced air cooling was performed for 30 minutes. This same cycle was repeated 8 times.

The numerical value of the corrosion resistance is the result of taking out the refractory test pieces after the test and cutting each at the center to examine (corrosion depth of the No. 9 test piece / corrosion depth of each test piece. )
Calculated by × 100, the larger the value, the better the corrosion resistance of the refractory material used as the lining material for stainless hot metal ladle. Further, the penetration resistance is the result of examining the penetration depth of the slag on the cut surface of the refractory test piece after being subjected to the corrosion resistance test, and the penetration depth of the refractory marked as "excellent" is 1 mm or less. Yes, the refractory marked "poor" had a penetration depth of 8 mm or more.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

In Tables 1 to 4, the unit of the numerical value of * 1 is% by weight and * 2 uses sintered magnesia as the aggregate. * 3 is the data for the standard refractories, * 4 is the data for the characteristics after heating at 200 ° C for 4 hours, and * 5 is the data for the characteristics after heating for 3 hours in an oxidizing atmosphere at 1500 ° C. The data.

Test Example Among the above-mentioned irregular shaped refractories, No. 1 and No. 3 compounded ones were prepared with a stainless hot metal ladle (50 tons) having an inner diameter of 255 cm at the top, an inner diameter of 240 cm at the bottom, and a depth of 300 cm. (Capacity) was applied to each of the molten metal contact parts, the temperature was raised to 800 ° C over 30 hours, and the durability was examined by using it for carrying stainless steel molten metal and comparing it with the conventional standard refractory material. The result exceeded the common sense that it was superior or inferior. That is, it was confirmed that the corrosion resistance was comparable to that of the conventional standard refractory, and the corrosion resistance was excellent as a whole because there was no erosion in the joint portion.

[0035]

The irregular refractory material of the present invention overturns the conventional wisdom that the regular refractory material has better durability, and has the same composition system as that used for the lining of the stainless hot metal ladle. It has been found that it exhibits the same corrosion resistance as that of the fired standard refractory, and as a result, the irregular refractory of the present invention exhibits excellent durability because it has no joints that are easily eroded.

By using the irregular-shaped refractory of the present invention as the lining of the stainless hot metal ladle, the durability of the refractory itself is not inferior, and the heavy work involved in the refractory replacement work. In addition to reducing the number of man-hours required for construction, labor saving can be achieved by this amount, and considering the effect of refractory saving such as adding and repairing refractory lining refractory in the ladle, The utility value above is enormous.

Claims (3)

[Claims] 1. Silicon carbide in an amount of 1 to 20% by weight excluding water.
%, Carbon 1-15%, alumina cement 0.5%
~ 5% and 3 to 13% of ultrafine powder composed of alumina and silica
%, With the balance consisting of an alumina-based aggregate , an amorphous refractory for a stainless hot metal ladle . 2. The soot according to claim 1, wherein the content of silicon carbide is 4 to 10% by weight and the content of carbon is 3 to 9% by weight .
Unshaped refractory for Tenres hot metal ladle . 3. The stainless hot metal according to claim 1 or 2.
Stainless hot metal ladle used in lining the ladle for monolithic refractories.