JPH1029875A - Composition for flow-in refractory material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. having excellent self fluidity which does not cause problems such as separation of an aggregate from a matrix or decrease in corrosion resistance by incorporating each specified amt. of a refractory aggregate, a specified refractory powder and sodium hexamethaphosphate. SOLUTION: This compsn. contains a refractory aggregate (e.g. Al2 O3 , SiC) (A) by 74 to 93wt.% of the sum of (A) and a refractory powder (B), an acid fumed silica fine powder (C) as one of (B) by 2 to 6wt.% and a powder as (B) except for (C) and having <=20μm particle diameter and <=10μm average particle diameter (e.g. alumina cement) by 5 to 18wt.%, and sodium hexamethaphosphate by 0.02 to 0.2 pt.wt. to 100 pts.wt. of the sum of (A) and (B). Thereby, the obtd. compsn. can be sent under pressure by a pump when the compsn. is used, and addition of vibration is not required for evacuated soil. Thus, the working labor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-flowing refractory composition suitable for use as a lining material for a blast furnace tapping gutter.

[0002]

2. Description of the Related Art A low-cement cast refractory with a low alumina cement content is used to transport kneaded clay from a kneading place to a construction location by a trolley, a bucket, a belt conveyor, etc., and then vibrate the clay with a vibrator. The work is poured by increasing the fluidity of the clay. The practical properties of a cast refractory depend on whether the fill fills every corner of the construction site and whether bubbles in the fill fill up and fill the refractory with a dense structure.

[0003] It is difficult to pour a refractory into a construction site having a complicated shape in which it is difficult to apply vibration to the clay with a vibrator. In addition, the construction work of applying vibration to the cover soil itself requires considerable labor. In recent years, in order to save labor for the work of casting refractories, self-fluidity cast refractories which can be constructed without vibration and can be pumped have been developed and are being put to practical use.

[0004] However, the conventional cast refractories for blast furnace tapping gutters do not have self-fluidity, and it is necessary to vibrate the transportation by a minecart, a bucket, a belt conveyor or the like and the cover soil at the time of construction. This requires considerable labor during construction (Japanese Patent Laid-Open No. 03-164479). On the other hand, if the mixing water volume is increased for these materials, self-fluidity is exhibited, pumping can be performed during construction, and there is no need to apply vibration to the clay, but the aggregate part and the matrix part separate. Or the corrosion resistance is reduced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a self-flowing cast refractory composition which is particularly suitable for blast furnace tapping gutters but which can be applied to other uses. It is in.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a refractory aggregate containing 74 to 93% by weight of the total amount of the refractory aggregate and the refractory powder. Acid fumed silica fine powder as an acidic powder is 2 to 6% by weight based on the total amount of the refractory aggregate and the refractory powder, and is a refractory powder other than the acidic fumed silica fine powder, having a particle diameter of 20 μm or less and an average particle diameter of 10 μm or less. 5 to 18% by weight of the total amount of the refractory aggregate and the refractory powder and 0.02 to 2 parts by weight of sodium hexametaphosphate per 100 parts by weight of the total amount of the refractory aggregate and the refractory powder. It is a composition for a cast refractory, characterized in that it contains parts by weight.

[0007] One of the desirable aspects of the present invention is that the clay immediately after the composition is kneaded by adding 8.0 parts by weight or less of water to 100 parts by weight of the composition is placed on a horizontal plate surface. Inside diameter 50mm, bottom inside diameter 100mm, height 150
2. A self-fluidity having a spreading diameter of 180 mm or more when poured into a truncated cone-shaped cone having an opening at the top and bottom of mm, and when the cone is pulled out and left without vibration for 30 seconds, It is a composition for a cast refractory as described above.

[0008] One of the preferred embodiments when the composition of the present invention is used for a blast furnace tapping gutter or a blast furnace pot is one containing silicon carbide aggregate as a main component as a refractory aggregate. One is to use alumina cement as the refractory powder.

Another desirable embodiment when the composition of the present invention is used for a lining material of a blast furnace tapping gutter or for a blast furnace pot is to use a carbonaceous aggregate together with an antioxidant as a refractory aggregate. It is.

In the present invention, the mixing ratio in the composition means the following unless otherwise specified.

First, as for the refractory aggregate and the refractory powder, the weight% in the total amount of the refractory aggregate and the refractory powder is shown. For components other than the refractory aggregate and the refractory powder, parts by weight are shown with respect to 100 parts by weight of the total of the refractory aggregate and the refractory powder.

In the present invention, the refractory aggregate is a main component of the refractory which imparts heat resistance and corrosion resistance to the cast refractory. As the refractory aggregate, those having a particle size distribution capable of obtaining a high packing density are preferable, and the refractory aggregate previously classified into coarse particles, medium particles and fine particles is remixed so as to obtain a high packing density. It is preferred to use one. If the packing density of the refractory aggregate can be increased, the amount of kneading water necessary to impart self-fluidity to the refractory powder and the clay can be reduced, and the cast refractory having a high bulk specific gravity with excellent refractory properties. Things are obtained.

The refractory aggregate has a larger particle size than the refractory powder and is usually used as a particulate having a particle size of more than 30 μm. As the refractory aggregate, various materials such as alumina, silicon carbide, silicon nitride, carbon, spinel, magnesia, and zircon can be used. As the material, alumina, silicon carbide, silicon nitride, carbon and the like can be desirably used.

The silicon carbide (SiC) material is obtained by
It is preferable that C contains 95% or more.
80% is preferred. This is because if it is less than 10%, it is difficult to obtain sufficient corrosion resistance for blast furnace tapping pans and gutters, and there is a risk of oversintering.
If it is more than 0%, a large amount of kneading water is required to impart self-flowability. In order to secure desirable corrosion resistance and fluidity, 15 to 45% is more preferable.

The carbon (C) material may not be used as a lining material for a blast furnace tapping gutter or a pot lining, or as a lining material for a cover of a tapping gutter, but is usually a desirable material.
Those containing 60% by weight or more of C by weight% are preferable, and flaky graphite whose surface is coated with pitch or the like, powder pitch or the like is appropriate.

The mixing ratio of the carbonaceous aggregate is preferably 0.5 to 5% as C. If the content is less than 0.5% by weight, the structure of the construction body after heating causes oversintering, and the refractory is easily peeled off. If the content is more than 5% by weight, the amount of water required for imparting self-flowability increases, and the oxidation resistance and abrasion resistance decrease. More preferably 1 to
4% by weight.

As the alumina, the one containing at least 95% by weight of Al ₂ O ₃ component such as fused alumina and sintered alumina is most suitable. Bauxite, mullite, ban clay, syrianite, kyanite, Those containing Al ₂ O ₃ as a main component, such as underlusite, can also be preferably used.

Alumina aggregate is a thermally and chemically stable material, and is relatively easily available. Therefore, it is a preferable aggregate when heat resistance and corrosion resistance are required. Is 7 to 70%.

The refractory powder is a component that fills the gaps between the particles of the refractory aggregate, bonds the refractory aggregates, and gives the refractory a bonding strength.

In the present invention, various kinds of refractory powders can be used. However, a specific amount of each of the acid fumed silica fine powder and the other specific fine powder is required.

First, as the acidic fumed silica fine powder, when fumed silica fine powder (10 g) is dispersed in ion-exchanged water (100 cc), the dispersion liquid becomes acidic p-side.
H (less than 6.5). When the pH of the dispersion is 6.5 or more, the working life is shortened. Since the pot life can be prolonged and the pump can be applied, the dispersion of the acidic fumed silica fine powder preferably has a pH of 4.5 or less.

As the acidic fumed silica fine powder in which the dispersion exhibits a pH value in such a range, those obtained as a by-product in producing a zirconia raw material by desiliconizing zircon can be preferably used.

When the amount of the acidic fumed silica fine powder to be incorporated in the composition for a cast refractory of the present invention is less than 2% by weight, excellent fluidity cannot be obtained, and when it is more than 6% by weight, the fire resistance decreases. Tend to. The content is preferably set to 3 to 5% by weight, since more favorable fluidity and fire resistance can be imparted. The average particle size of the acid fumed silica fine powder is 2μ.
m or less, more preferably 1 μm or less.

Next, as the refractory powder other than the acid fumed silica fine powder, 5 to 18% of particles having a particle diameter of 20 μm or less and an average particle diameter of 10 μm or less are blended. If the amount is less than 5% by weight, a large amount of kneading water is required to impart self-fluidity to the kneaded clay, and if the amount is more than 18% by weight,
This is because excessive sintering occurs during drying and use of the construction body, and it is easy to peel off. Preferably, the content is 6 to 17% by weight.

In the present invention, such refractory powders include:
It is optimal to use alumina cement as part of this. This is because the refractory containing alumina cement as the refractory powder in the composition of the present invention has sufficient practical strength from room temperature to the high temperature at which the refractory is used after being cast and cured after being cast. Because you can. If the amount of alumina cement is less than 0.5%, the hardening time becomes longer, and practical and good constructional strength may not be obtained. If it is more than 3%, the pot life becomes shorter and the corrosion resistance is reduced. I do. In order to obtain better construction strength, pot life and corrosion resistance, the content is set to 1 to 2.5%.

The refractory powder includes one or more powders selected from the group consisting of alumina such as Bayer alumina, mullite, chamotte, spinel, magnesia, zirconia silicon nitride and silicon carbide, in addition to the above-mentioned acidic fumed silica and alumina cement. It can be used preferably.

In the present invention, the ratio of the refractory aggregate to the refractory powder is 74 to 93% for the former and 26 to 7% for the latter, and thus the object of the present invention can be achieved. The material texture is obtained.

The present invention relates to a casting composition, and a dispersant is necessary for kneading a composition comprising these with water to obtain a clay having self-fluidity. In the composition of the present invention, sodium hexametaphosphate is optimally used as the dispersant. The amount of the sodium hexametaphosphate used in the composition of the present invention is 100 masses of the refractory aggregate and the refractory powder.
0.02 based on parts by weight as Na ₆ P ₆ O ₁₈
０．２0.2 parts by weight. This is because if the amount is less than 0.02 part, the dispersing effect is not obtained in the composition of the present invention, and if the amount is more than 0.2 part, the dispersing effect is not further improved. It is preferable to mix one part.

When a carbonaceous aggregate is used as the composition of the present invention, there is a high possibility that the carbonaceous aggregate will be oxidized during the operation in which it is exposed to an oxidizing atmosphere after the application, so it is necessary to add an antioxidant. Become.

As the antioxidant, metals such as silicon and aluminum, alloys, silicon carbide, zirconium boride, boron carbide and the like can be used. It is sufficient that the antioxidant is added in an amount of 0.5 part by weight based on 100 parts by weight of the total amount of the refractory aggregate and the refractory powder. In addition, when an antioxidant and carbon aggregate are frequently used, it is preferable to add relatively much.

The kneaded clay which is usually kneaded by adding 4 parts by weight or more of water to 100 parts by weight of the composition of the present invention can be poured into the corner of the mold without being vibrated when poured into the mold. It has a self-flowing property that flows into the mold and fills the inside of the formwork, and air bubbles inside the clay are floated to the surface and eliminated. In the present invention, the degree of fluidity of the fill is evaluated by the following method.

That is, immediately after the water was added to the composition and kneaded, the clay was placed on a horizontal plate surface and had an upper inner diameter of 50 mm.
Pour it into a cone (bottom frustoconical shape punched up and down) with a bottom inner diameter of 100 mm and a height of 150 mm and fill it. Pull out the cone and leave it standing for 30 seconds without applying any vibration. The spreading diameter of the bed soil when fluidized is measured with calipers in two directions perpendicular to each other,
The average value (hereinafter referred to as a flow value) is used as a liquidity index. The preferred self-flowing refractory fill material of the composition of the present invention which can be applied without vibration has a flow value of 180 mm or more.

[0033] The flow value of the fill is greater when the amount of water mixed into the fill is greater. If the mixing amount of water is the same, the greater the fluidity, the better the workability, and the more preferable fill value of the clay is 200 mm or more. When pouring in the refractory pavement of the present invention having good self-flowing property, no work involving heavy labor for shaking the pavement is required at all, and the kneaded pavement using a pump is used at the construction site. By adopting the construction method of transferring to, further labor saving is possible.

The amount of water mixed with the composition varies depending on the specific gravity and porosity of the refractory aggregate and refractory powder contained in the composition. There is a lower limit to the amount of water that can impart fluidity to the kneaded clay, and usually, 4 parts by weight or more of water is required for 100 parts by weight of the total amount of the refractory aggregate and the refractory powder. Further, in order to reduce the porosity of the refractory after construction and to secure good physical properties as the refractory, the amount of water mixed with the composition of the present invention is determined by the total amount of the refractory aggregate and the refractory powder. 1 of quantity
It is preferably at most 8 parts by weight, more preferably at most 6 parts by weight, based on 00 parts by weight. If the amount of water mixed with the composition is large, the refractory aggregate tends to settle, and the installed refractory is likely to be heterogeneous.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

The refractory aggregate which is a main component of the cast refractory composition includes coarse particles (particle diameter: 8 to 1 mm) and medium particles (fused alumina particles) containing 97% by weight of Al ₂ O _3. Particle size 1
mm), fine particles of sintered alumina aggregate containing 99% by weight of Al ₂ O ₃ (particle diameter of 0.043 mm or less), and 9% of SiC.
Coarse grain of silicon carbide aggregate containing 5% by weight (particle size: 4 to 1 m
m), medium grain (particle diameter 1 mm or less), fine grain (particle diameter 0.15 m)
m) and fine powder (particle size 0.01 mm or less), C is 60
Powder pitch fine particles (particle diameter of 1.2 mm or less) were used as a carbonaceous raw material containing by weight.

The acidic fumed silica contains 9 of SiO ₂ .
Fumed silica A containing 3% by weight (average particle size 0.8μ)
m, pH 3) and fumed silica B containing 98% by weight of SiO ₂ (average particle size 1 μm, pH 8) were used.

Other refractory powders include Al ₂ O ₃ containing 99.
Bayer alumina powder containing 6% by weight (average particle size 4.3μ)
m, including 100% of particles having a particle size of 20 μm or less), Al ₂ O
Alumina cement containing 72.5% by weight of ₃ and 26% by weight of CaO (containing 70% of particles having an average particle size of 5.6 μm and a particle size of 20 μm or less) was used.

The silicon powder used had a Si purity of 99% by weight or more and a particle size of 100 μm or less.

The dispersants include sodium hexametaphosphate having a content of P ₂ O ₃ and Na ₂ O of 69.6% by weight and 30.4% by weight, respectively, and a content of P ₂ O ₃ and Na ₂ O respectively. 53.4% and 46.6% by weight of anhydrous sodium pyrophosphate were used.

Compositions of Examples 1 to 16 (Examples 1, 7 to 11 and 13 to 15) in which these raw materials were mixed at the mixing ratios shown in Tables 1, 2 and 3 (all unspecified mixing amounts are by weight). Is an example, and Examples 2 to 6, 12, and 16 are comparative examples), and the same amount of water as described in Tables 1, 2, and 3 is mixed with the composition to obtain a cover, and the cover is prepared by the method described above. Was evaluated for fluidity.

The corrosion resistance was evaluated by pouring the clay of each composition into a mold, removing the mold after 24 hours, drying at 110 ° C. for 24 hours, and then heating the specimen at 400 ° C. for 5 hours. . The erosion test is an induction furnace, using pig iron and slag,
Performed at 1550 ° C. for 5 hours. As an index of corrosion resistance, a corrosion resistance index was used. The higher the corrosion resistance index, the higher the corrosion resistance.

The evaluation of the oversinterability was performed by drying a sample collected from the sprayed body at 110 ° C. for 24 hours, and then drying the sample at 1000 ° C.
, And the breaking strength of the construction body fired at 1400 ° C was measured. When the ratio of the breaking strength between the 1000 ° C fired product and the 1400 ° C fired product (1400 ° C / 1000 ° C) is 1.5 or more, it is considered that there is a peeling phenomenon.

In Tables 1, 2, and 3, a circle indicates that the intensity ratio is 1.5.
△ indicates that the value slightly exceeded 1.5, but among the uses for blast furnace gutters, it can be sufficiently used as a gutter lid or the like.

Regarding the presence or absence of material separation after the construction of the cast refractory, the clay just after the kneading was set to an inner diameter of 100 mm and a height of 20 mm.
It was poured into a 0 mm mold and filled, and after standing for 24 hours, the refractory was taken out of the mold and separation of the aggregate portion and the matrix portion was confirmed from the cut surface.

The proportion of the refractory powder having a specific particle size in Tables 1, 2 and 3 means that the powder having a particle size of 20 μm or less and an average particle size of 10 μm or less other than the fumed silica powder in the prepared composition. Indicates the amount.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

As described above, there is no self-fluidity in the conventional refractory for casting blast furnace tapping gutters and the like, and it is necessary to apply a vibration to the bucket and the clay during the construction. Need. On the other hand, for these materials,
Increasing the amount of kneading water causes self-fluidity to be exhibited, pumping can be performed at the time of construction, and it is not necessary to apply vibration to the clay, but the aggregate part and the matrix part are separated and the corrosion resistance is reduced. was there.

On the other hand, in the composition for a cast refractory according to the present invention, 2 to 6% by weight of acidic fumed silica fine powder and refractory powder other than acidic fumed silica fine powder having a particle size of 20 μm or less and an average By using 4 to 18% by weight of the refractory powder having a particle diameter of 10 μm or less and 0.02 to 0.2 part by weight of sodium hexametaphosphate, there is a problem that the aggregate portion and the matrix portion are separated or the corrosion resistance is reduced. In addition, pumping can be performed at the time of construction, and there is no need to apply vibration to the clay, which reduces construction labor.

The use of carbonaceous aggregate and alumina cement makes a more desirable casting composition for blast furnace gutters.

Claims (6)

[Claims] 1. A refractory aggregate comprising 74 to 93% by weight of the total amount of the refractory aggregate and the refractory powder, and an acid fumed silica fine powder as the refractory powder in the total amount of the refractory aggregate and the refractory powder. 2-6
% By weight of a refractory powder other than the acid fumed silica fine powder and having a particle size of 20 μm or less and an average particle size of 10 μm or less.
% By weight of sodium hexametaphosphate and 0.02 to 0.2 parts by weight based on 100 parts by weight of the total amount of the refractory aggregate and the refractory powder.
A composition for a cast refractory, comprising parts by weight. 2. A bed clay immediately after mixing and kneading 8.0 parts by weight or less of water to 100 parts by weight of the above composition, placed on a horizontal plate surface, having an upper inner diameter of 50 mm, a lower inner diameter of 100 mm, and a height of 1 mm.
A self-fluidity having a spreading diameter of 180 mm or more when poured into a 50 mm frusto-conical cone-shaped cone having an open top and bottom, and when the cone is pulled out and left without vibration for 30 seconds, the spreading diameter of the clay is 180 mm or more. The composition for a cast refractory according to the above. 3. The composition according to claim 1, wherein the refractory powder contains alumina cement in an amount of 0.5 to 3% by weight based on the total amount of the refractory aggregate and the refractory powder. 4. The composition according to claim 1, wherein the refractory aggregate contains 10 to 80% by weight of silicon carbide in the total amount of the refractory aggregate and the refractory powder. 5. The method according to claim 1, wherein the refractory aggregate contains carbon in an amount of not more than 5% by weight based on the total amount of the refractory aggregate and the refractory powder.
The composition according to 2, 3 or 4. 6. The composition according to claim 5, further comprising an antioxidant.