JPS604152B2 - Refractory manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a refractory.

More specifically, the present invention relates to a method for producing a refractory using a phosphate or polyphosphate of a cyanamide compound as a binder for a refractory raw material. Conventionally, clay, cement, sodium silicate, bentonite, organic glue, or phosphoric acid compounds have been used as binders for refractories, depending on the type of refractory and purpose of use.

Among these, known phosphoric acid compounds include phosphoric acid, sodium phosphate, aluminum phosphate, ammonium phosphate, aliphatic amine salts or alkanolamine salts of phosphoric acid, condensed sodium phosphate, and condensed potassium phosphate. However, none of them are necessarily satisfactory as binders that can be applied to modern fireproof equipment, and they have various drawbacks, such as the following. In other words, when phosphoric acid or acidic aluminum phosphate is used, a refractory with high bonding strength can be obtained both at room temperature and in hot conditions, but since it is a strongly acidic viscous liquid, it corrodes metal equipment and is not refractory. It reacts with the metal content present in the material and causes foaming, which not only shortens the life of the equipment and reduces the finishing accuracy of the molded product, but also impairs workability and prevents uniform mixing with the refractory material. causing financial harm such as making it difficult.

In addition, it is particularly reactive to basic refractory raw materials,
Since the mixture solidifies quickly, it is difficult to maintain an appropriate working time from drilling to construction. When using sodium phosphate, condensed sodium phosphate, condensed potassium phosphate, etc., the alkali metal ions contained exhibit a kind of flux action during firing of the refractory,
Since the refractory level is significantly lowered, high-grade refractories cannot be manufactured.

Ammonium phosphate or aliphatic amine salts of phosphoric acid generate ammonia gas or unpleasant amine odor when kneaded or fired with refractory raw materials, which significantly pollutes the working environment.

Furthermore, alkanolamine salts of phosphoric acid are liquids or highly hygroscopic powders, which have poor workability and are difficult to handle.

For liquid or highly hygroscopic powder binders such as phosphoric acid, aluminum phosphate, or alkanolamine phosphate, do not add them in advance to powder or granular materials such as refractory mortar or castable refractories. It is impossible to transport it to the construction site.

The present inventors aimed to improve the various drawbacks of the above-mentioned phosphoric acid compound refractory binders, and to find industrially and economically useful refractory binders that do not cause environmental pollution. As a result of intensive research, we have arrived at the present invention.

The present invention consists of producing an excellent refractory by using a phosphate or polyphosphate of a cyanamide-based compound having a guanyl group as a binder for a refractory raw material.

A refractory binder is added to the refractory material, which is the main raw material, for the purpose of increasing bonding strength and improving workability, regardless of whether it is a molded or unshaped refractory. The refractory binder used is a phosphate or polyphosphate of a cyanamide-based compound having a guanyl group, such as dicyandiamide, guanylurea, piganide, guanidine, or guanyl melamine, and has the general formula (wherein R is -N ratio, -NHCN, or, n is an integer of 1 to 3 or 150 to 60,000, and x is a number of 1 to n12.

) is a non-hygroscopic white powdery substance. The refractories produced according to the present invention are of all kinds.

That is, it applies to any refractories that are basic, neutral, or acidic in terms of raw materials, regardless of whether they are molded or shaped, fired or unfired. Also, normal methods and equipment are used for its manufacture. In the present invention, the type and amount of binder used for the refractory raw material varies somewhat depending on the type of refractory and the purpose of use, but the amount used is generally 1 to 2% by weight based on the refractory raw material. A range of is preferred.

As for the binder, the use of one type of the above-mentioned binder is usually sufficient and effective, but if necessary, two or more types can be used at the same time. It is also possible to use it in combination with a modifier. The binder of the present invention can be obtained by any manufacturing method as long as it has the above-mentioned structural formula, but it is usually a combination of a cyanamide compound having a guanyl group and phosphoric acid or polyphosphoric acid. A compound produced by a sum reaction or a double decomposition reaction between a mineral salt of a cyanamide compound having a guanyl group and an alkali metal phosphate or an alkali metal polyphosphate is used. All of the cyanamide compounds having a guanyl group, which are raw materials for the refractory binder, have all carbon atoms in the molecule bonded to two or more amino or imino type nitrogen atoms, and the number of nitrogen atoms is equal to the number of carbon atoms. It is a basic substance with a structure that is 2 to 3 times larger.

These series of base monsters are usually chemicals derived directly or indirectly from cyanamide; for example, dicyandiamide is obtained by treating cyanamide with a weak alkali, and guanylurea and guanidine are obtained by treating dicyandiamide with a strong acid. , biguanide is obtained by treating dicyandiamide with mineral acid ammonium salt. Phosphoric acid, polyphosphoric acid, or an alkali metal salt thereof, which is the other raw material of the refractory binder, is subjected to the reaction in the form of an aqueous solution,
They are processed according to conventional methods, but the concentration of their aqueous solutions is
It can be determined arbitrarily.

The refractory binder is general formula (In the formula, R, n, and illusion are the same as above.

), but if phosphoric acid or an alkali metal phosphate is used as the starting material, a product with n of 1 can be obtained, if polyphosphoric acid is used, a product with n of 1 to 3 can be obtained, and an alkali metal salt of polyphosphate can be obtained. If n is 2 to 3, then 150 to 6
Gives 0000 products. The above-mentioned alkali metal polyphosphates include sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium acid pyrophosphate, sodium hexametaphosphate, sodium ultraphosphate, and polymerization degree of 150~
60,000 potassium metaphosphate and the like are commonly used. In producing the refractory binder, the reaction molar ratio of phosphoric acid, polyphosphoric acid, or an alkali metal salt thereof to the cyanamide compound having a guanyl group or its stannate is not particularly limited, and the binder It is chosen arbitrarily so that the aqueous solution has the desired pH value.

Generally, the product with a reaction molar ratio of 1:1 is the first salt, the product with a 2:1 ratio is the second salt, and the product with a reaction molar ratio of 3:1 is the tertiary salt.
The product of :1 is called a salt, but the binder of the present invention is
It includes not only products with such integer molar ratios but also products with intermediate molar ratios.

Usually, a 1% aqueous binder solution with a mottling value in the range of 6 to 10 is often preferred, but binders that fall within this preferred range include diguanidine phosphate, diguanylurea phosphate, bisdicyandiamide phosphate, phosphoric acid Examples include pyguanide, diguanyl melamine phosphate, tetraguanidine pyrophosphate, tetraguanyl urea pyrophosphate, tetraguanidine tripolyphosphate, pentaguanyl urea tripolyphosphate, and polyguanidine polyphosphate.

If an acidic salt is required, for example, monoguanidine phosphate, diguanylurea pyrophosphate, or monoguanyl melamine phosphate is used. In the present invention, in order to uniformly mix the refractory raw material and the binder, it is preferable to adjust the binder to an appropriate particle size in advance depending on the purpose of use. In recent years, as fireproof equipment has become larger and more complex, the influence of refractory binders has become greater.
That choice is becoming increasingly important.

According to the present invention, since the binder used is a non-hygroscopic powder, it is easy to handle, store, and transport, and it is also possible to mix the binder and the refractory raw material in advance for storage or transport. becomes.

Therefore, the inconvenience of mixing the binder and the refractory raw material at a refractory construction site is eliminated, and construction efficiency is improved. This is particularly true for mortar and castable materials, which have been shown to significantly improve construction efficiency compared to conventional methods. Furthermore, since the binder and the refractory raw material can be mixed uniformly in powder form, there is no inconvenience in kneading or non-uniform distribution of the molded product, which occurs with liquid binders, and therefore no cracks occur during firing.

In addition, since the binder according to the present invention exhibits neutral to weak basicity in water soot, no foaming phenomenon is observed even when it is blended and kneaded with refractory raw materials containing a small amount of metal. Not only can a processed product with high finishing accuracy be obtained, but it also does not corrode fireproof equipment.

Furthermore, since the reactivity of the binder with respect to the refractory material at room temperature is extremely mild, a sufficiently long working time can be maintained during molding or processing after adding water and kneading. This effect is particularly noticeable in basic non-mound-forming bricks, air-hardened refractory mortars, basic castable refractories, and the like. For example, the time required for initial solidification of a kneaded product obtained by adding 5% by weight of the binder to a basic castable refractory raw material is about 1. This is a significantly longer time than that for the secondary phosphoric acid or acidic aluminum phosphate, which is almost instantaneous. Therefore, the binder facilitates work management even in large-scale and complicated construction. Furthermore, if 3% by weight of the binder is added to the clay mortar raw material, not only can a high-quality mortar thickened product be obtained without foaming at all, but also the workability is improved, such as good stiffness and trowel release. This enables smooth mortar construction.

Furthermore, since the binder does not contain alkali metals, it is possible to produce high-grade refractories with improved fire resistance, and the range of applications of the binder is expanded.

In addition, when producing refractories according to the present invention, no harmful gas or bad odor caused by the binder is observed at all, and the working environment is not contaminated.

In addition, the refractory obtained by the present invention has excellent physical properties such as high bonding strength and compressive strength and bending strength that are equal to or higher than those of conventional phosphoric acid compound binders. As described above, according to the present invention, by using a refractory binder that is easily available or manufactured and has a number of advantages that cannot be achieved with conventional binders, various types of excellent refractories can be processed. It can be easily manufactured.

Therefore, the industrial and economic benefits brought about by the present invention are extremely large. Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A refractory raw material consisting of 30 parts of chromium ore (containing 20343% Cr) and 70 parts of seawater magnesia clinker (containing 094% Mg), each having a maximum particle size of 3 ribs, was mixed with 5 parts of tetradaanyl urea pyrophosphate and 5 parts of water. was added and kneaded into a uniform slurry.

During kneading, there was no foaming phenomenon or generation of unpleasant odor, and a fine-grained, high-quality kneaded product was obtained.

Then, take a certain amount of mixed wires and use a hydraulic press to
Molded under the pressure of 00k9' flow and molded at 250qo
After drying for several hours, the compressive strength was measured and found to be 720k9/
It was a pleasure. 1. Other molded and dried products manufactured in the same manner
When fired at 300℃, there was no dimensional change before and after firing, no cracks were observed, and the hot bending strength was 8.5K.
It was 9' ground.

Example 2 Clay mortar material with a maximum particle size of 0.8 grains or less (AI2
0343%, containing 0247% Si), 4 parts diguanidine phosphate adjusted to a maximum particle size of 0.4 feet, and 7 parts water.
After adding 50% of the total amount and mixing it uniformly, mortar was applied.

During the above-mentioned mixing, no foaming phenomenon or generation of off-odor was observed, and a slurry with good consistency and troweling was obtained.

The processed product was left to stand naturally for 3 hours, then dried at 11000 for 2 hours, and its compressive strength and bending strength were measured, and they were 11.3k9' and 5.1kg', respectively.

Example 3 Bauxite (N20361
% content) Isobe, fireclay with a maximum particle size of 0.5 skin or less (A
3 parts of phosphoric acid dicyandiamide adjusted to a maximum particle size of 0.1 grain and 8 parts of water were uniformly added to a fireproof mortar material consisting of 1 cornerstone (I20335%, SiQ 45% content) and 2 parts of magnesia clinker (Mg094% content). A mortar slurry was prepared by mixing the moat and construction was carried out.

During the above kneading, no foaming phenomenon or generation of foul-smelling gas was observed, and a slurry with good stickiness and troweling was obtained. The constructed product was left to stand naturally for 3 hours and the compressive strength and bending strength were measured, and the results were 13.0 kg' and 4.5 kg, respectively.
It was about kg'.

Examples 4-10 Particle size distribution is 6.5 side ~ 14 mesh 38.4%, 14 ~
18 meshes 16.9%, 48-325 meshes 33.
0%, 11.7% magnesia clinker under 325 mesh muscle (contains Mg094%, Si023%, Fel%)
To 95 parts, 5 parts of phosphates or polyphosphates of cyanamide-based compounds having various guanyl groups were added individually, 8.5 parts of water was added, and the mixture was uniformly mixed to form a mixture of 4 x
It was poured into a formwork measuring 4 yards x 16 yards.

During mixing, there was no foaming or generation of off-odor, and a fine-grained kneaded product with good workability was obtained regardless of which salt was used.

The table below shows the type of salt added, the time from pouring into the mold to initial solidification (setting time), the compressive strength after being left to stand for 2 hours, and the temperature between 800qo and 1200℃.
shows the compressive strength after firing.

There was no dimensional change before and after firing. [
Note] (1) The average degree of polymerization of the boriphosphoric acid group is 180.

Claims (1)

[Claims] 1 General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R is -NH_2, -NHCN, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ Numerical formulas, chemical formulas, tables, etc. ▼ where x indicates the number from 1 to n+2) is added and used as a binder in the range of 1 to 20% by weight of the cyanamide compound phosphate represented by ) to the refractory raw material. , the phosphate group in the formula is orthophosphoric acid (
n=1), pyrophosphoric acid (n=2), tripolyphosphoric acid (n
= 3) or polyphosphoric acid having a degree of polymerization (n) of 150 to 60,000.