JPS6291472A - Refractory composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dog composition with excellent workability, strength, and fire resistance.

Traditionally, alumina cement has been mixed with refractory aggregate and used as castable refractories for furnace materials, etc.
The amount of alumina cement mixed in castable refractories is usually 12 to 3, because the dispersibility is relatively poor and even if the amount is increased, the strength does not increase much and the fire resistance decreases.
It was 0% by weight. However, even in this case, the high-temperature strength and high-temperature ITPt corrosion resistance were lowered, and there were problems with fire resistance due to the influence of CaO contained in the alumina cement. In order to improve this, there was an attempt to reduce the amount of alumina cement mixed to 5 to 8 parts by weight, but this resulted in poor workability during construction and insufficient strength even when molded. .

The present inventor has discovered that in conventional products, the amorphous component (C is Ca
O, A to A (1203, F to Fe2O3, S to 5i02
Then, the main mineral corresponds to CA, and in addition, CA2. Cl2A7. Mineral components containing small amounts of C4AF and C2AS) are 30 to 40% by weight, and this is made into a fine powder by staying in a ball mill for a long time and pulverizing it, so the particle shape is fine on the surface. After extensive research, we found that the particles were substantially spherical with little unevenness and had many internal cracks.A9. Contains 40 to 70 weight percent of 203, and when one particle is measured by the sedimentation balance method, the particle size is 30 g or less, of which particles of 5 pL or less are 10 to 35 weight percent, and the specific surface area is 0.5 to 1. It was discovered that castable obtained by blending alumina cement with particle size of .2 m'/g, which is not substantially spherical, has excellent workability, strength, and fire resistance, leading to the completion of the present invention. .

To produce the alumina cement used in the present invention, clinker is produced from a raw material blend of alumina cement by firing or melting, and then quenched by contacting with air or water, and the cooling rate is adjusted to form an amorphous cement. The ingredients are adjusted to 40-80% by weight. A Q20. The content is 40~
The raw materials are mixed so that the amount is 70% by weight. Then, the alumina cement clinker is pulverized by a rapid pulverizer such as a jet mill or a roller mill, and the particle size is measured by a sedimentation balance method. 35% weight, specific surface area 0.5-1.2rrf
/g. Jet mills and roller mills are of the forced passage type using air, and the residence time is within about 1 minute.

The alumina cement used in the present invention has more amorphous components than conventional products, so when it is ground with a rapid grinder such as a jet mill or roller mill, the surface becomes uneven, acicular, and square. A mixture of columnar, bullet-like and various angular shapes that are not substantially spherical is obtained,
There were also fewer internal cracks. This material has the particle size and specific surface area described above, has excellent workability such as dispersibility and fluidity, and has high strength when molded.

As the amorphous component increases, the content of angular components increases, but if it is less than 40% by weight, the working time is short and the strength is slightly reduced. On the other hand, if the content exceeds 60% by weight, curing becomes significant, which is not preferable.

Further, if the A9203 content exceeds 70 hairs and 9%, the curing time will be significantly delayed, and if the content is less than 40 double stars, the working time will be too short to be suitable for practical use. In addition, the particle size structure of alumina cement is an important factor in workability. In other words, in normal commercial products, there are 10 to 20 products that do not pass through a 30 μ sieve
By weight, particles with a particle size of 5IL or less are about 35-45% heavy acid, but coarse particles that do not pass through a 30JL sieve have a slow hydration reaction and poor dispersibility, so coarse particles are mixed in. It is preferable that there is little. Therefore, the particle size (Stokes diameter measured by the sedimentation balance method) of the alumina cement used in the present invention was set to be 30 colors or less. In addition, if a large amount of 5 pL or less, which has particularly high activity, is present, workability will be impaired; on the other hand, if it is absent, the development of strength will be delayed.
The content of particles of 5 or less particles is preferably 10 to 35% by weight. Depending on the case, the materials classified by a classification step may be appropriately blended.

In the present invention, the reason why the particle size of alumina cement is measured by the sedimentation balance method (buoyancy balance method) is as follows.

Since cement is a hydraulic powder, various dry and wet particle size measurement methods have been studied, but no definitive measurement method has been established to date. Normally, cement is made by grinding clinker in a mill for a long time, and its particle shape is close to spherical.Since it is essentially a spherical fine powder, the sedimentation balance method is adopted as a method for measuring the particle size of cement. ing. On the other hand, the particle shape of the alumina cement of the present invention is a non-spherical fine powder that is different from the particle shape of conventional cement, but the sedimentation balance method was adopted because it allows relative comparison with conventional products and has excellent reproducibility. be.

The fireproof composition of the present invention contains (A) the above-mentioned amorphous component at 40%
~60% by weight and AQ203 of 40~70 double stars:% The particle size when measured by the star shadow and sedimentation balance method is 30% or less, of which 10~35% by weight are particles with a size of 5p or less, and the specific surface area is Alumina cement whose particle shape is not substantially spherical and whose particle size is 0.5 to 1.2 rrf/g.
(C) 2 to 10 parts by weight of a powder of the following refractory material with a particle size of 10; (Dl) 75 to 96 parts by weight of refractory aggregate; (E) a dispersant; (A) , (B) , (C
) and 0.1 to 1.0% by weight based on the total amount of (D)
It consists of Although this refractory composition has a small content of alumina cement, it exhibits excellent workability, strength, and fire resistance when used in castable refractories such as furnace materials.

The refractory material (B) is particularly effective in assisting the dispersion of alumina cement. For example, siliceous
Alumina, zirconia, chromia, and calcia are preferred, and ultrafine silica powder is particularly preferred. Particle size is particle size l river leeward (average particle size 0.1~0.5J
L), preferably 100 mg or less, preferably spherical in shape, and must be water-insoluble. If the amount added is less than 1 part by weight, the effect of the dispersion aid will not be sufficient and preferred viscosity will not be obtained when the fireproof composition of the present invention is hydrogenated and kneaded. If it exceeds 5 parts by weight, there will be adverse effects such as delayed curing and decreased strength, and the viscosity during kneading will increase more than necessary.

The refractory material of component (C) is an important element constituting the matrix of the refractory together with the alumina cement and the refractory material of component (B), and contributes to improving strength by increasing the filling properties of the matrix. and also improves fire resistance. Examples of the refractory material of component (G) include silica, alumina, zirconia, chromia, and calcia, and the lower the water absorption, the better the results. The particle size is 10. Below (average particle size 4~
8 pieces), and those containing 80% by weight or more of 5 river lees are particularly preferred. If the amount added is less than 2 parts by weight, no improvement in filling properties can be expected, and if it exceeds 10 parts by weight, the particle size structure will not be appropriate and the filling properties will be impaired.

Examples of the refractory bone phase of the component (D) include silica, chamotu, alumina, magnesia, maguro, spinel, silicon carbide, and carbon.
Any particle having a particle size of 30 mm or less may be used. For example 10
It is preferable that particles passing through a 0.5 mm sieve in an amount of about 20% by weight are included.

Below, components (A), (B), (C), and (Tl) are blended in the proportions described above, but the reason for specifying the blending amount of each component is that castable with excellent dispersibility cannot be obtained outside this range. This is because the strength of the refractory material cannot be obtained sufficiently when it is molded.

In the present invention, in addition to the above components, the above (A) dispersant is used.
, (B), (c), and (o) in an amount of 0.1 to 1.0% by weight based on the total amount. Examples of dispersants include sodium tripolyphosphate, sodium hexametaphosphate, acidic sodium hexametaphosphate, aluminum phosphate,
Inorganic salts such as sodium boric acid, boric acid, and sodium carbonate, sodium citrate, sodium tartrate, and polyacrylic soda! I can give you salt. In the present invention, the dispersant is 1
Of course, it is possible to use different types, but it is better to use two or more types in combination to obtain preferable results.

When applying the fireproof composition of the present invention, 8% by weight or less of water is usually added and kneaded before use. In conventional fireproof compositions, 12 to 25% by weight of water was added, so in the case of the product of the present invention, a significantly smaller amount is sufficient compared to the conventional product.
Therefore, the obtained molded product has the advantage that there is little increase in porosity after dehydration by drying or baking, and little decrease in strength.

EXAMPLES The present invention will be explained in more detail with reference to Examples below. The percentages in the examples are percentages by weight unless otherwise specified.

In addition, the test was measured by the following method.

(1) Flow (ff1m): Fill a flow cone with the kneaded material according to the method described in JIS R5201, smooth the surface, pull the flow cone vertically upward, and then vibrate at 8000 PPM for 10 minutes using a vibrator.
Gave seconds. The spread of this kneaded material was measured with a caliper, and the average value (am) of the major axis and minor axis was taken as the flow measurement value.

Note that the larger the flow measurement value, the greater the fluidity of the kneaded material due to vibration.

In addition, the same operation was performed 30 minutes later and the flow was measured.
When calculating the difference between the flow measurement values after 3 minutes and after 30 minutes,
The smaller the difference, the better the linearity. Note that the linearity refers to the workability (ease of construction) when the material is left to stand after being kneaded with water.

(2) Curing time: 40×4 while applying vibration to the kneaded material
It was poured into a 0x180 (mm) mold and hardened. The time from the addition of water to the composition until it generates heat was defined as the curing time.

(3) Strength (kg/crrf): Strength after pouring the cured product obtained in (2) into a mold as a test piece and leaving it for 24 hours, strength after drying at a temperature of 110°C, 1000°C and 1400°C The strength and linear change rate after firing were measured according to the following method.

Bending strength: JIS R2553 Compressive strength: JIS R2553 Baking bending strength: JIS R2553 Linear change rate: JIS R2554 Example 1 Production of alumina cement Bauxite and quicklime were mixed so that the molar ratio of CaO and AL1203 was 1:1. Then, it was melted at about 1650°C in a resistance electric furnace. This molten material was blown out at an air pressure of 5 kg/cm' when tapping from inside the furnace, and quenched with air to produce clinkers of the present invention shown in Tables 1 and 2.

The conventional product was manufactured in the same manner except that the air pressure was 2 kg/cryf.

The composition of the rivets and materials in Table 2 was determined as follows. Ta.

Mineral components are identified by the peak positions of crystal components by X-ray diffraction. The ratio of the crystalline component to the amorphous component is determined based on the peak of the crystalline component of the mineral component estimated from the raw material composition. That is, a calibration curve of peak heights of known ratios is created in advance, and then the ratios are determined from the crystalline peak heights at that time.

This clinker is processed using a roller mill for the products of the present invention.
Conventional products were ground in a ball mill to produce alumina cement. The shape of each particle was examined using an m-microscope (
S, E, M) (magnification: 1000 times) revealed that the products of the present invention were not substantially spherical as shown in Figure 1, while the conventional products were substantially spherical as shown in Figure 2. It was something. In addition, Shimabara Seisakusho rSR-100O
Particle size was measured by a sedimentation balance method using a J model. The particle size distribution was as follows.

In addition, the specific surface area of the product of the present invention was 0.758 m'/
g, the conventional product was 2.505rrf/gte.

The following tests were conducted on products of the present invention and conventional products.

Using the alumina cement manufactured in the above alumina cement manufacturing process, the mixture was mixed in the proportions shown in Table 4, put into a mixer, and stirred for 3 minutes, then 6.5% water was added thereto, and the mixture was mixed for another 3 minutes. While stirring and measuring the flow, the kneaded product was subjected to various tests, and the results are shown in Table 5.6.

Examples 2 to 7 The same procedure as in Example 1 was conducted except that the blending ratios of alumina cement, ultrafine silica, alumina, and Otabi Chamotte were changed. These conditions and results are shown in Tables 7, 8, and 9.

Examples 8 to 10 The same procedure as in Example 1 was carried out except that the ratio of the refractory aggregate (A) and the material other than this aggregate (B) was changed to make it castable. These conditions and results are shown in Tables 10, 11, 12, and 13.

Example 11 The procedure was the same as in Example 1 except that the proportion of the dispersant to 100 parts of the castable formulation was changed.

(Leaving space below) Table 4 (Part) Table 5 Table 6 Table 8 Table 9 Table ■7 As detailed above, the present invention is characterized by workability, particularly workability in a high-temperature atmosphere, hardenability, strength, and fire resistance. It is an alumina cement-based refractory M1 composition with excellent alumina cement, and castable containing a small amount of this has excellent dispersibility and high strength as a molded product, whereas conventional castable is difficult to use due to high temperature strength and corrosion resistance. This is an extremely useful invention, as it can be used for steel-related furnace materials such as soaking furnaces, heating furnaces, annealing furnaces, cement, and non-ferrous metals.

[Brief explanation of drawings]

FIG. 1 is a micrograph showing the particle structure of alumina cement used in an example of the present invention. FIG. 2 is a micrograph showing the particle structure of a conventional alumina cement used as a comparative example.

Claims (1)

[Scope of Claims] 1 (A) 40 to 60% by weight of amorphous component and Al_
Contains 40 to 70% by weight of 2O_3, and when measured by the sedimentation balance method, the particle size is 30μ or less, of which 10 to 35% by weight is 5μ or less, and the specific surface area is 0.5 to 1.
．． 1 to 10 parts by weight of alumina cement having a particle size of 2 m^2/g and whose particle shape is not substantially spherical; (B) 1 to 5 parts by weight of a refractory material powder having a particle size of 1 μ or less; (C) particle size (A), (B), (C), and (D) 2 to 10 parts by weight of powder of a refractory material of 10μ or less, (D) 75 to 96 parts by weight of refractory aggregate, and (E) a dispersant. A fireproof composition comprising 0.1 to 1.0% by weight based on the total amount of.