JPH08157266A - Composition for chamotte flowed-in refractory - Google Patents

Abstract

PURPOSE: To provide a composition for chamotte flowed-in refractory exhibiting self-fluidity with a small quantity of water to be added, capable of pressure transporting by a pump and showing the same bulk density as the conventional vibration worked refractory. CONSTITUTION: The composition for chamotte flowed-in refractory consists of 72-93wt.% chamotte aggregate having >20μm particle diameter, 3-10wt.% acidic fumed silica fine powder, 4-18wt.% fire resisting powder except the acidic fumed silica fine powder and having <=20μm particle diameter and <=10μm average particle diameter, and a small quantity of a dispersing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is
TECHNICAL FIELD The present invention relates to a chamotte pouring refractory composition having excellent fluidity, which can be poured by a pump for construction.

[0002]

BACKGROUND ART Irregular refractories typified by cast refractories generally have a smaller bulk specific gravity after the construction than the preformed regular refractory (brick) and the fire resistance after the construction. It is said that the smaller the bulk specific gravity of the product, the poorer the durability. However, the number of manpower required for both manufacturing and construction is remarkably small, and there is an advantage that energy saving can be achieved because firing is unnecessary. Particularly recently, the dispersibility of the kneaded clay obtained by adding water to the cast refractory composition, that is, the fluidity of the kneaded clay is improved, and the amount of water added to the kneaded clay can be reduced. A cast refractory with a large bulk specific gravity after construction has been developed, and the durability of the cast refractory has been improved, and it is becoming more dominant than the standard refractory in terms of cost performance.

Thus, the irregular shaped refractory, especially the cast refractory, is replacing the conventional shaped refractory in places, and the amount thereof is increasing year by year. Further, recently, a pouring refractory having self-fluidity capable of pumping pressure by controlling the amount of water in the kneaded clay by using a dispersant having good performance has begun to be put into practical use.

However, the above-mentioned cast refractory having self-fluidity that enables pumping has a large amount of water content as compared with the cast refractory that is cast by applying normal vibration. There is a problem that the bulk specific gravity of the cast refractory after the construction is small due to the large amount of water mixed in, and thus the durability is poor.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of conventional cast refractories, and enables pouring without vibration, which has not been achieved in the prior art.
It has self-fluidity that allows pumping, and the bulk specific gravity of the construction refractory obtained is comparable to that of cast refractories constructed by adding conventional vibration. Chamotte pouring refractory composition The purpose is to provide things.

[0006]

The present invention has a particle size of 20 μm.
72 to 93% by weight of super chamotte aggregate, 3 to 10% 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 particle size of 10 μm or less 4 to 18% by weight of powdery powder,
A chamotte cast refractory composition comprising a small amount of a dispersant. In the following, “a refractory powder other than acidic fumed silica fine powder having a particle size of 2
The "refractory powder having an average particle size of 0 µm or less and 10 µm or less" is simply referred to as "refractory powder".

In the cast refractory composition of the present invention,
Acid fumed silica fine powder is contained as a component for improving the fluidity of kneaded clay. The acidic fumed silica fine powder has a pH value (less than 6.5) on the acidic side when the fumed silica fine powder is dispersed in ion-exchanged water. As such an acidic fumed silica fine powder, a dispersion thereof preferably exhibits a pH of 4.5 or less, and as an acidic fumed silica fine powder in which the dispersion exhibits a pH value in such a range, zircon is desiliconized. The thing obtained as a by-product at the time of processing and manufacturing a zirconia-type raw material can be used preferably.

When the amount of the fine powder of acidic fumed silica blended in the composition for a cast refractory of the present invention is less than 3% by weight, excellent fluidity cannot be obtained, and when it is more than 10% by weight, the fire resistance is lowered. Tend to do. Since it is possible to impart better fluidity and fire resistance, it is preferably 5 to 9% by weight. The average particle size of the acidic fumed silica fine powder is 2μ.
It is preferably m or less, and more preferably 1 μm or less.

The chamotte aggregate is the main component of the chamotte cast refractory and is a refractory raw material having a particle size of more than 20 μm, which is produced by firing a raw material mainly made of clay mineral. Preferably, the amounts of coarse particles, medium particles, and fine particles are adjusted so that the bulk specific gravity of the obtained refractory material is increased.

Both the refractory powder and the acidic fumed silica fine powder are components that form a bonding portion that fills the gaps between the particles of the chamotte aggregate, and the amount of the acidic fumed silica fine powder added is 3 to 10% by weight. On the other hand, the blending amount of the refractory powder is set to 4 to 18% by weight, which is a blending amount suitable for filling the gaps between the particles of the aggregate.

The optimum blending amount of the components of the bonding portion varies to some extent depending on the particle size distribution of the aggregate, but if the amount exceeds the above range or is too small, the required fluidity is imparted to the kneaded clay. If the amount of water required to do so increases, and the amount of water increases, the bulk specific gravity of the refractory to be constructed decreases. Also, if the amount of the fine-grained component forming the joint is too large, the refractory will shrink due to heating during use, causing cracks, and the thermal shock resistance will decrease as the refractory shrinks due to shrinkage. To do.

The refractory powder to be added to the composition includes alumina cement, alumina, titania, bauxite, diaspore, mullite, gravel shale, chamotte, pyrophyllite, sillimanite, andalusite, silica stone, chrome ore, spinel, Powders of magnesia, zirconia, chromia, silicon nitride, aluminum nitride, silicon carbide, zirconium boride, titanium boride and the like can be used. Practically, other than alumina cement added as a binder, one or more selected from relatively inexpensive alumina, bauxite, diaspore, mullite, gravel shale, chamotte, pyrophyllite, sillimanite, andalusite and silica stone. It is preferable to blend the refractory powder of.

Since the refractory powder has an average particle size of 10 μm or less, a kneaded material having good fluidity can be obtained with a small amount of water. In the present invention, the average particle size means a particle size at which the cumulative weight in the weight cumulative particle size distribution obtained by using a laser diffraction particle size distribution meter is 50% by weight.

The cast refractory composition of the present invention has a top end inner diameter 50 in which 100 parts by weight of the composition and 6.5 parts by weight of water are mixed and kneaded, and the kneaded material is placed on a substantially horizontal surface.
mm, a bottom inner diameter of 100 mm, and a height of 150 mm, and a truncated cone-shaped cone type (a slump cone defined in JIS-A1101 has a top inner diameter of 100 mm, a bottom inner diameter of 200 mm, and a height of 300 mm.
It has excellent flowability such that the flow value (extended dimension of kneaded clay) is 180 mm or more when it is poured into a two-dimensional one) and left without vibration for 60 seconds in a state where the cone mold is pulled out upward.

If the flow value of the puddle of the refractory for pouring is 180 mm or more, the puddle can be pumped at the time of construction, and the bubbles inside the puddle poured into the puddle will naturally float up without vibration. Then, the kneaded clay flows into every corner of the formwork without any gaps, so that the time required for the construction work can be remarkably shortened, the workers can be freed from heavy labor, and a great labor saving can be achieved in the construction.

The cast refractory composition of the present invention exhibits a flow value of 180 mm or more even when the amount of water mixed with the composition is relatively small at 6.5% by weight on the outside. A chamotte pouring refractory kneaded clay having a water content of 6.5% by weight and having this level of fluidity has not been realized by conventional techniques. Due to the relatively small amount of water in the kneaded clay, the bulk specific gravity of the constructed refractory becomes large, and it is possible to prevent the coarse aggregate in the kneaded clay from settling out and making it non-uniform. It can provide excellent chamotte pouring refractory.

Since the larger the flow value of the kneaded clay is, the better the workability is, the flow value under the same conditions as described above is preferably 200 mm or more, further 220 mm or more.
On the other hand, the smaller the amount of water in the kneaded clay mixed with water, the better the bulk specific gravity and durability of the refractory after construction. Therefore, the amount of water added should be reduced to achieve the required fluidity. Once the kneaded material is obtained, it is preferable to apply the kneaded material with a reduced water content. Further, when the amount of water mixed in the composition of the present invention is further reduced and the composition is poured by a conventional method of applying vibration, a refractory material having a large bulk specific gravity and excellent durability can be constructed.

In the cast refractory composition of the present invention, the alumina cement conventionally used for cast refractories can be used as a binder. In this case, it is preferable to include 2 to 10% by weight of alumina cement in the composition as a part of the refractory powder in the composition. By setting the content of alumina cement in the composition to be 2 to 10% by weight, the necessary and sufficient strength required for the refractory can be imparted. Even if the content of alumina cement in the composition is increased to more than 10% by weight, an advantage commensurate with the increased cost of the raw material cannot be obtained.

If the amount of the dispersant to be added to the composition for a cast refractory of the present invention is small, the dispersing effect will not be sufficiently exhibited,
If the amount is too large, the dispersion effect does not improve, and the phosphoric acid component may adversely affect the product quality such as steel materials, and it may reduce the fire resistance of the constructed refractory, so that it is preferably applied outside. The total amount is 0.02-1.0% by weight,
More preferably, the total amount of external coating is 0.04 to 0.5% by weight.
It is said.

As the dispersant, various dispersants such as polymetaphosphates, polycarboxylates, polyacrylates and β-naphthalenesulfonates which have been conventionally used for cast refractories (surfactants are used. However, in order to give better flowability to the kneaded clay of chamotte cast refractory, sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate,
It is preferable to contain one or more selected from sodium tetrapolyphosphate.

[0021]

EXAMPLES The present invention will be specifically described below with reference to Examples (Examples 7 to 16) and Comparative Examples (Examples 1 to 6), but the present invention is not limited thereto. Table 1 shows the purity of the fumed silica fine powder (hereinafter abbreviated as HS), the pH of the dispersion, and the average particle size of the fumed silica fine powder blended in the composition in the following examples. Table 1
Inside, HS-A is a fumed silica fine powder obtained when desilicing zircon.

[0022]

[Table 1]

As the chamotte aggregate (hereinafter abbreviated as CH), the contents of Al ₂ O ₃ , SiO ₂ and Fe ₂ O ₃ are 43% by weight, 53% by weight and 0.9% by weight, respectively. Coarse particles with a diameter of 1.68-5 mm, 0.1-1.6
8 mm medium particle size, particle size 0.1-20 μm, average particle size 3
An aggregate composed of 0 μm fine particles was used.

Alumina cement (hereinafter abbreviated as AC) having refractory particles of Al ₂ O ₃ and CaO of 74% by weight and 24% by weight, respectively, and an average particle size of 5.5 μm.
A powder and a Bayer alumina (hereinafter abbreviated as BA) powder having a purity of Al ₂ O ₃ of 99.6% by weight and an average particle diameter of 4.3 μm were used.

The compositions having the formulations shown in Tables 2 and 3 were prepared,
The physical properties of the kneaded materials obtained by adding the indicated amounts of water to these compositions and kneading them, and the chamotte cast refractories formed by casting these kneaded materials were examined.

As the dispersant, sodium hexametaphosphate (hereinafter abbreviated as HP) containing P ₂ O ₅ and Na ₂ O of 69.6% by weight and 30.4% by weight, respectively, and P
Sodium tetrapolyphosphate having a content of ₂ O ₅ and Na ₂ O of 60.4 wt% and 39.6 wt% (hereinafter,
TPP) and sodium tripolyphosphate (hereinafter abbreviated as TP) having contents of P ₂ O ₅ and Na ₂ O of 57.9% by weight and 42.1% by weight, respectively were used.

[0027]

[Table 2]

[0028]

[Table 3]

The fluidity evaluation test was carried out by adding a predetermined amount of water to the compositions of the formulations shown in Tables 2 and 3 and kneading in a universal mixer for 3 minutes. Pour into a cone-shaped cone with an inner diameter of 100 mm and a height of 150 mm, pull the cone out upwards, and
It was left without vibration for 0 seconds, and the average value of the maximum spreading dimension of the kneaded clay that spread in a substantially circular shape and the spreading dimension in the direction orthogonal thereto was obtained and used as the flow value. The dispersants and the amounts of added water in Tables 2 and 3 are all external weight%.

Regarding the self-fluidity, the kneaded material prepared in the same manner as described above is heated to 230 m within 1 minute after kneading with a mixer.
When poured into a mold with internal dimensions of m × 230 mm × 230 mm, the surface of the poured kneaded clay becomes horizontal, and the bubbles inside the kneaded clay float up and are released from the surface of the kneaded clay. There was.

For the porosity and bulk specific gravity, the same kneaded clay has an inner dimension of 40 m.
What was poured into a m × 40 mm × 80 mm mold was 20
Leave in a room at ℃ for 24 hours, then remove from the mold, then at 110 ℃ for 2
The test piece dried for 4 hours was measured according to JIS-R2205. The compressive strength is 40 mm x 40 mm x 40 mm in the center of the dried test pieces.
The metal block of No. 2 was pressed and the maximum compressive load at the time of crushing was obtained and used as the compressive strength. In the comparative example, a satisfactory molded product was not obtained, and thus the physical properties were not examined.

[0032]

EFFECTS OF THE INVENTION The cast refractory composition of the present invention gives a kneaded clay having good self-fluidity when externally added with 6.5% by weight of water and kneaded. Since self-fluidity can be obtained with a relatively small amount of water of 6.5% by weight or less, air bubbles are released from the surface and cast into every corner of the mold without any vibration during construction. In addition, the bulk specific gravity of the constructed refractory is not inferior to that of the refractory that is poured by applying conventional vibration.
Excellent durability as a refractory material.

Further, by utilizing the excellent self-fluidity of the kneaded material of the refractory and pouring it by pumping, further labor saving and shortening of the construction period can be achieved in the construction of the refractory, and the cost performance is further improved. You can secure your romance.

Claims (5)

[Claims] 1. A chamotte aggregate 72 having a particle size of more than 20 μm
93% by weight, 3 to 10% by weight of acidic fumed silica fine powder, and 4 to 18% by weight of refractory powder other than acidic fumed silica fine powder having a particle size of 20 μm or less and an average particle size of 10 μm or less. A chamotte pouring refractory composition, which comprises a small amount of a dispersant. 2. A kneaded material obtained by adding 6.5 parts by weight of water to 100 parts by weight of the composition of claim 1 and kneading the mixture is placed on a substantially horizontal surface, and the inner diameter at the upper end is 50 mm, the inner diameter at the bottom is 100 mm, and the height is 100 mm. 1
The flow value when pouring into a cone-shaped cone having a truncated cone shape with an opening of 50 mm at the top and bottom, pulling out the cone-type upward, and leaving it for 60 seconds without vibration is 180 mm or more.
Chamotte pouring refractory composition of. 3. The chamotte cast refractory composition according to claim 1 or 2, wherein the acidic fumed silica fine powder is obtained as a by-product when desilicing zircon to produce a zirconia-based raw material. 4. A composition containing 2 to 10% by weight of alumina cement as a part of the refractory powder.
The chamotte cast refractory composition according to any one of 3 above. 5. The dispersant is one or more selected from sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate and sodium tetrapolyphosphate, and the compounding ratio of the total amount of the dispersant is 0 to the composition. ．
The chamotte pouring refractory composition according to any one of claims 1 to 4, which is from 02 to 1.0% by weight.