JPH07316615A - Sleeve-shaped refractories for blast furnace tap hole - Google Patents

Abstract

PURPOSE:To lessen the reactivity with molten iron and molten slag, to impart excellent hot strength, wear resistance and thermal crack resistance characteristics to sleeve-shaped refractories for a tap hole, to prevent expansion of the tap hole and to make tapping stabler and longer in time by forming the refractories of refractories consisting of a silicon carbide, silicon nitride and alumina. CONSTITUTION:The compsn. of refractories contains, by weight, 50 to 85% silicon carbide (SiC), 5 to 40% silicon nitride (Si3N4) and 5 to 30% alumina (Al2O3) as essential components. The total content of such silicon carbide, silicon nitride and alumina is >=90%. The refractories are formed by adding an SiO2 inorg. binder and water to a compd. composed of the prescribed amt. of the silicon carbide, silicon nitride and alumina powders and kneading the mixture, then packing the mixture into water absorptive casting molds under excitation and molding the refractories to a cylindrical shape. This molding is then dried and is sintered in a nitrogen atmosphere, by which the sleeve-shaped refractories are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve-shaped refractory which is installed in the taphole of a blast furnace to form the taphole.

[0002]

2. Description of the Related Art The tap hole of a blast furnace is made of silicate material and / or high alumina material mixed with SiC material and Si ₃ N ₄ material.
It is blocked by filling a clay-like amorphous refractory called a mud material using a closing machine (mad gun). Then, at the time of tapping, an opening machine is used to drive a gold rod into the mud material that closes the tapping hole, and punch it to open the rod.

In recent years, blast furnace operation has been performed by blowing fuel such as heavy oil, pitch, pulverized coal, etc. into the furnace from tuyere along with hot air. Therefore, the amount of tapping metal is increased, the non-tapping time is shortened, the opening and closing work of the tapping tap for tapping is frequent, and the degree of work under high heat has increased. Further, in the conventional mud material, erosion and wear due to hot metal and slag during tapping are large, and stable operation cannot be performed due to enlargement of tap hole. For example, the current tapping time is generally about 3 to 4 hours, and the tapping frequency per day is about 6 times.

Since the opening and closing of the taphole is a work in a bad environment of high heat, the increase of the taphole opening and closing work has many environmental and safety problems. If the mud material filled in the taphole is heavily melted, it is not only difficult to carry out the tapping work stably, but also the main gutter, skinmer part, and hot metal gutter that serve as the hot metal runway. As a result of severe operating conditions such as slag gutters, etc., the damage is severe.

Therefore, a mud material made of a dough-shaped amorphous refractory containing the above silicate material and / or high alumina material as a main material and at least one of a carbon material, a silicon carbide material and a silicon nitride material is mixed therein. However, such mud materials have not yet solved the above problems.

In order to solve the above-mentioned problems, Japanese Patent Laid-Open No.
Japanese Patent No. 205610 discloses a method (hereinafter referred to as prior art) for forming a taphole by attaching a refractory cylinder, that is, a sleeve-shaped refractory material to the punched taphole. . According to the prior art, the sleeve-shaped refractory attached to the taphole reduces wear and expansion of the taphole during tapping, and as a result, long-time tapping is possible. The number of times of opening and closing can be reduced.

[0007]

However, in order to achieve the above-mentioned effects by the prior art, the material of the sleeve-shaped refractory material attached to the tap hole becomes a problem. That is, the sleeve-shaped refractory has low reactivity to hot metal and molten slag, has high hot strength and viscosity, and has excellent wear resistance at high temperatures, and has high resistance to thermal stress.
Although it is required to have the property of not easily cracking, according to the prior art, a sleeve-shaped refractory material that can satisfy the above-mentioned requirements cannot be obtained, and therefore, the intended purpose has not been achieved. .

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a sleeve-shaped refractory to be mounted on the taphole of a blast furnace, which has low reactivity to hot metal and slag and has high hot strength and viscosity. Moreover, it has excellent wear resistance at high temperatures, high resistance to thermal stress, and has the property of being difficult to crack. Due to such characteristics, there is little expansion of the tap hole due to hot metal, and long time tapping is possible. (EN) Provided is a sleeve-shaped refractory for blast furnace tapping, which enables the number of tapping cycles to be reduced.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems. As a result, silicon carbide (SiC), which is a material with low reactivity with hot metal and molten slag
C), silicon nitride (Si ₃ N ₄ ) and alumina (Al ₂ O ₃ ) as three essential components, and limiting the content of each of them and the total content to a specific range, in order to obtain high density, If a sleeve-shaped refractory is formed by sintering this in advance, the sleeve-shaped refractory has high hot strength and viscosity, and is excellent in wear resistance at high temperature, and It has been found that a property having high resistance to thermal stress is imparted.

The present invention has been made on the basis of the above findings, and the sleeve-shaped refractory material of the present invention comprises silicon carbide (SiC): 50 to 85 wt.%, Silicon nitride (Si ₃ N ₄ ): 5 to 40 wt.% And alumina (Al ₂ O ₃ ): 5 to 30 wt.% As essential components, and the silicon carbide (SiC)
The total content of the silicon nitride (Si ₃ N ₄ ) and the alumina (Al ₂ O ₃ ) is 90 wt.% Or more.

[0011]

The reason for limiting the chemical composition of the sleeve-like refractory of the present invention as described above will be described below. (1) Silicon Carbide (SiC): The SiC material has improved hot strength and hot wear resistance and is excellent in heat conductivity. However, when the content of SiC is less than 50 wt.%, The strength and the thermal conductivity are lowered and the corrosion resistance is deteriorated. on the other hand,
If the SiC content exceeds 85 wt.%, The cohesive strength of the structure will be weakened and the hot wear resistance will deteriorate. Therefore, the content of SiC should be limited to the range of 50 to 85 wt.%.

(2) Silicon nitride (Si ₃ N ₄ ): Si ₃ N ₄ material enhances the bond strength of the structure and is excellent in impact resistance. However, if the content of Si ₃ N ₄ is less than 5 wt.%, The effect of improving the bond strength of the structure is small and the coefficient of thermal expansion is high, and the impact resistance is deteriorated. On the other hand, when the content of Si ₃ N ₄ exceeds 40 wt.%, The corrosion resistance deteriorates. Therefore, the content of Si ₃ N ₄ should be limited to the range of 5-40 wt.%. In addition,
Si ₃ N ₄ is obtained by forming a Si ₃ N ₄ material and / or a Si material and reacting and sintering this in a nitrogen atmosphere.

(3) Alumina (Al ₂ O ₃ ): Al ₂ O ₃ material improves corrosion resistance and strength. However, when the content of Al ₂ O ₃ is less than 5 wt.%, The effect of improving the cohesive strength of the structure is small, while when the content of Al ₂ O ₃ exceeds 30 wt.%, The spalling resistance is weakened. Cracks are likely to occur. Therefore Al
The content of ₂ O ₃ should be limited to the range of 5 to 30 wt.%.

(4) SiC + Si ₃ N ₄ + Al ₂ O ₃ : the above SiC, Si
The total content of ₃ N ₄ and Al ₂ O ₃ needs to be 90 wt.% Or more. When the total content of SiC, Si ₃ N ₄ and Al ₂ O ₃ is less than 90 wt.%, It generally depends on the mixed materials, but it generally causes deterioration of corrosion resistance, hot strength and impact resistance, and shortens the service life. Problems such as coming will occur.

FIG. 4 is a schematic front view of the sleeve refractory material of the present invention, FIG. 5 is a schematic side view thereof, and FIG. 6 is a view showing a state in which the sleeve refractory material is attached to the blast furnace tap hole, which is a schematic vertical view of the tap hole portion. FIG. As shown in FIGS. 4 and 5, for example, the inner diameter D _1: 40 mm, outer diameter D _0: 90 mm, Length L: cylindrical sleeve refractory 1 500mm, as shown in FIG. 6, the opening of the blast furnace It is mounted in the tap hole 2 thus formed by an opening machine. Therefore, since the hot metal tapped from the blast furnace is discharged through the sleeve refractory 1 installed in the tap tap 2, the spread of wear of the tap tap 2 due to the hot metal and the slag is small, and the long time is long. Can be tapped.

[0016]

EXAMPLES Next, the sleeve refractory material of the present invention will be described in more detail by way of examples. Example 1 A silicon carbide material having the chemical composition shown in Table 1,
A refractory material composed of a silicon nitride material, a silicon material, an alumina material and a pyrophyllic material and having a grain size constitution shown in Table 2 was used.

[0017]

[Table 1]

[0018]

[Table 2]

Silicon carbide-based materials, silicon nitride-based materials, silicon-based materials, alumina materials and wax-based materials having the chemical composition shown in Table 1 are compounded in the proportions shown in Table 3 as materials No. 1 to 6 for the present invention. Then, the obtained compound was added to the SiO ₂ inorganic binder 2
wt.%, and water 4.5 wt.% were added and kneaded.

Next, the obtained kneaded product was filled in a water-absorbent mold while vibrating, molded into a cylindrical shape in the mold, and then dried. Then, the dried cylindrical molded product was placed in a sintering furnace, and in a nitrogen atmosphere, the maximum temperature was 1550.
After sintering at 65 ° C. for 65 hours, it was naturally cooled in the furnace.
Thus, the specimens of the sleeve-like refractory of the present invention having the chemical composition shown in Table 4 (hereinafter referred to as the specimen of the present invention) No. 1
6 was prepared.

For comparison, silicon carbide-based material, silicon nitride-based material, silicon-based material, alumina material and wax-based material having the above chemical composition are blended in the ratios shown in Table 3 as comparative materials Nos. 1 to 4. Then, comparative sleeve-like refractory specimens (hereinafter referred to as comparative specimens) Nos. 1 to 4 shown in Table 4 in which at least one has a chemical composition outside the range of the present invention were prepared.

[0022]

[Table 3]

[0023]

[Table 4]

Incidentally, the Si ₃ N ₄ /Si=166.7 and the added amount of 6.3 wt.% Of the siliceous material was 10 wt.% Of Si ₃ N ₄ by reaction sintering in a nitrogen atmosphere. become.

The quality characteristic values of each of the above-mentioned test sample of the present invention and the test sample for comparison, that is, room temperature and 1400 ° C.
Bending strength (Kg / cm ² ) and compressive strength (Kg / cm ² )
² ) was investigated and the results of the investigation are shown in Table 5.

FIG. 1 is a graph showing the quality characteristic values of Table 5. In FIG. 1, double circles indicate compressive strength, white circles indicate bending strength at room temperature, and black circles indicate bending strength at a temperature of 1400 ° C.

[0027]

[Table 5]

[0028] As apparent from Table 4 and Table 5 and FIG. 1 Tokyo, comparative specimens No.1 not containing Al ₂ O _3, the content even though containing Al ₂ O ₃ is the invention Comparative sample No. 2, which was out of the range and was small, had low bending strength and compressive strength at room temperature and 1400 ° C. The content of SiC is small outside the range of the present invention, and the content of Al ₂ O ₃ is large outside the range of the present invention. Comparative sample No. 3 and SiC + Si ₃ N ₄ + Al Comparative sample No. 4, in which the amount of ₂ O ₃ was out of the range of the present invention, was also low in bending strength and compressive strength at room temperature and 1400 ° C.

On the other hand, each of the contents of SiC, Si ₃ N ₄ and Al ₂ O ₃ and the total contents thereof are within the scope of the present invention. Both the bending strength and the compressive strength at 1400 ° C. are high, and particularly, as in the case of the present invention sample Nos. ₂ to 4, the Al ₂ O ₃ content is 10 to 20 wt.%.
In the case of, the strength was remarkably improved.

[Example 2] Silicon carbide-based materials, silicon nitride-based materials, silicon-based materials, alumina materials and wax-based materials having the chemical composition shown in Table 1 are shown in Table 6, and materials No. 7 to 13 for the present invention are shown in Table 6. Samples Nos. 7 to 13 of the present invention having the chemical component compositions shown in Table 7 were prepared in the same manner as in Example 1 except that the components were mixed in the proportions shown below. For comparison, Table 6 shows the blending ratio of the material No. 2 for the present invention, and Table 7 shows the chemical composition of the sample No. 2 of the present invention.

For comparison, silicon carbide-based material, silicon nitride-based material, silicon-based material, alumina material and wax-based material having the above chemical composition are blended in the proportions shown in Table 6 as comparative materials Nos. 5-8. Then, Comparative Specimens Nos. 5 to 8 having at least one having a chemical composition outside the range of the present invention and shown in Table 7 were prepared.

[0032]

[Table 6]

[0033]

[Table 7]

Regarding each of the above-mentioned test sample of the present invention and the test sample for comparison, quality property values thereof, that is, bending strength (Kg / cm ² ) and compressive strength (at room temperature and 1400 ° C.) as in Example 1, were obtained. Kg / cm ² ) was investigated, and the results of the investigation are shown in Table 8.

[0035]

[Table 8]

FIG. 2 is a graph showing the quality characteristic values of Table 8. In FIG. 2, double circles indicate compressive strength, white circles indicate bending strength at room temperature, and black circles indicate bending strength at a temperature of 1400 ° C.

As is apparent from Tables 7 and 8 and FIG. 2, comparative specimens No. 5 and S containing no Si ₃ N ₄ were added.
Comparative sample No. 6, which contained i ₃ N ₄ and contained in a small amount outside the range of the present invention, had low bending strength and compressive strength at room temperature and 1400 ° C. Comparative sample No. 7 having a large Si ₃ N ₄ content outside the range of the present invention, and a small amount of SiC + Si ₃ N ₄ + Al ₂ O ₃ outside the scope of the present invention for comparison Specimen No. 8 also had low bending strength and compressive strength at room temperature and 1400 ° C.

On the other hand, the specimens Nos. 7 to 14 of the present invention in which the respective contents of SiC, Si ₃ N ₄ and Al ₂ O ₃ and the total contents thereof were within the range of the present invention, were at room temperature and 1400 ° C. Both the bending strength and the compressive strength were high.

[Example 3] At the tap hole of a blast furnace having a furnace capacity of 2828 m ³ , the inner diameter of 40 mm and the outer diameter of 90 mm according to the sample No. 3 of the present invention and the sample No. 3 for comparison shown in Example 1 Each sleeve refractory with a length of 500 mm was installed or filled with conventional mud material for operation. Table 9 shows the tapping time in each case, and FIG. 3 shows the relationship between the tapping time and the tapping speed.

[0040]

[Table 9]

As is apparent from FIG. 3 and Table 9, when the sleeve refractory made of the specimen No. 3 of the present invention was attached to the taphole, the sleeve refractory made of the specimen No. 3 for comparison was used. As compared with the case of mounting and the case of filling with the conventional mud material, the tapping hole is less enlarged, so that the tapping can be performed for a long time, and therefore the number of tapping times is reduced.

[0042]

As described above, according to the present invention,
As a sleeve refractory to be installed at the tap hole of a blast furnace, it has low reactivity to hot metal and slag, high hot strength and viscosity, excellent wear resistance at high temperature, and resistance to thermal stress. A refractory that is high and resistant to cracking can be obtained.By installing this sleeve refractory in the taphole of the blast furnace, wear and expansion of the taphole due to hot metal and slag are reduced, and therefore long-time tapping is prevented. As a result, it is possible to reduce the number of times of tapping, which is an industrially useful effect.

[Brief description of drawings]

FIG. 1 is a graph showing quality characteristic values of a test sample of the present invention and a test sample for comparison in Example 1.

FIG. 2 is a graph showing quality characteristic values of a test sample of the present invention and a test sample for comparison in Example 2.

FIG. 3 is a graph showing the relationship between the tapping time and the tapping speed when tapping is performed using the present invention specimen and the comparative specimen.

FIG. 4 is a schematic front view of the sleeve brick of the present invention.

5 is a schematic side view of FIG.

FIG. 6 is a schematic vertical cross-sectional view of a taphole portion showing a state in which the sleeve refractory material of the present invention is attached to the taphole of the blast furnace.

[Explanation of symbols]

 1 sleeve refractory, 2 taphole.

Front Page Continuation (72) Inventor Hideaki Inoue 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Kikuo Ariga 51-1 Toki-cho, Mizunami-shi, Gifu (72) Inventor Kato Masakazu 3-1 Ohatacho, Tajimi City, Gifu Prefecture

Claims (1)

[Claims] 1. A sleeve-shaped refractory which is installed in a blast furnace taphole to form the taphole, wherein the sleeve-shaped refractory is made of silicon carbide (SiC): 50 to 85 wt.%, Silicon nitride. (Si ₃ N ₄ ): 5 to 40 wt.% And alumina (Al ₂ O ₃ ): 5 to 30 wt.% As essential components, and the silicon carbide (Si
C), the silicon nitride (Si ₃ N ₄ ) and the alumina (Al ₂ O ₃ )
The total content of is 90 wt.% Or more,
Sleeve-shaped refractory for blast furnace tap.