JPS62119171A - Monolithic refractories - 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 monolithic refractories used in the construction and repair of blast furnaces, converters, electric furnaces, ladles, and other industrial kilns, and more specifically to works using granular phosphate as a compounding component. The present invention relates to a monolithic refractory with improved durability and durability.

In recent years, monolithic refractories have been developed for industrial furnaces such as blast furnaces, converters, electric furnaces, etc., with the aim of reducing furnace material costs by extending the life of the furnace and improving productivity, especially caster pull refractories and spray-repair refractories. The use of refractories has become essential.

These monolithic refractories are generally made of refractory aggregate as the main material, a binder, and other additives, and when used, they are kneaded with water, molded, painted, or sprayed, and then treated. In this case, alkali metal salts of 6-layer phosphates, especially condensed phosphates, are widely used as binders, peptizers, or hardening modifiers.

Phosphate salts are usually used in powder form, but due to moisture absorption, the particle surface becomes sticky and forms solids.
Not only is it difficult to disperse uniformly in the refractory material, which hinders the kneading operation, but also the obtained refractory material is non-uniform and brittle, reducing its durability. In addition, hot spraying using the Mesly Remix method is widely used for spray repair, but since water is instantly kneaded and gun spraying is performed immediately, the moisture absorption and caking properties of phosphate are critical to the work. It becomes an obstacle.

The inventors have conducted extensive research in order to eliminate the above-mentioned disadvantages of phosphates, and by making phosphates, which were conventionally used in powder form, into granules, they have solved the problem caused by the moisture absorption peculiar to phosphates. The present invention was completed based on the discovery that not only could the troubles associated with the process be solved, but also that a refractory material with a higher degree of fire resistance and excellent durability could be obtained.

The granular phosphate used in the present invention has an extremely large specific surface area, and therefore is a highly fluid material with a high void volume ratio, and can be produced by various methods as described in JP-A-6-36314. can. That is, a dry granulation method using an injection granulator, an agitation granulator, a crushing granulator, a fluidized granulator, a pan-type granulator, a drum-type granulator, a compactor, or a method using a micron granulator. However, methods that are particularly effective for the purpose of the present invention include dry granulation, in which raw phosphate is once formed into a plate shape, and then pulverized to a desired particle size; After spraying and granulating to desired particle size,
Examples include a method of heating and drying to remove added moisture to obtain granules, and a fluidized granulation method of dispersing raw material fine powder particles in an air stream and spraying water to granulate them to a desired particle size. In both cases, fine powder particles are made into granules by immersion in water, and X-ray diffraction results show that the surface of the resulting granules is covered with crystalline phosphate that is stable in water. It is confirmed. Therefore, despite having an extremely large specific surface area, it has high moisture resistance and fluidity, and has extremely good solubility in water, preventing the formation of sticky lumps and lumping seen in powdered phosphates. It has the unique property of not causing any trouble at all.

Refractories containing such granular phosphates do not absorb moisture and solidify during storage, and can be stored stably for long periods of time.The phosphates dissolve extremely quickly even when mixed with water. As a result, kneading and spraying operations are facilitated, and a highly uniform slurry is formed, resulting in a homogeneous and highly durable refractory material. Additionally, basic aggregates are often mixed with acidic phosphates, but in this case, the reaction between the aggregates and phosphates tends to cause trap μ, but it is recommended to use stable granular acidic phosphates. Additionally, the contact surface with the basic aggregate is reduced, and caking due to reaction is avoided, and workability is greatly improved in this respect as well.

To explain the effects of the present invention more specifically, for example, in castapul refractories, sodium pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, sodium ultraphosphate, etc. are used as deflocculants. The reaction between the material and the binder, alumina cement, is adjusted, that is, the so-called setting time from kneading to molding and solidification is controlled. On the other hand, since the durability of castapul refractories is said to depend on the properties of its matrix, there has recently been a trend to suppress the addition of alumina cement binders, which tend to generate low-melting compounds, as much as possible, reducing the amount of alumina cement used. Cementless caster pull containing high molecular weight, highly condensed phosphate with strong peptizing and dispersing effects is gaining importance, and there is an increasing demand for denser and higher strength refractory materials.

The granular phosphate of the present invention can also meet these requirements. That is, granular phosphate has good solubility;
Since it dissolves quickly in the slurry, it exhibits a sufficient peptizing effect even when added in a small amount compared to conventional powdered phosphates, making it possible to reduce the amount of water in the slurry. The refractory material obtained by this method is more dense, and the explosion and peeling phenomena caused by the heat increase after molding caused by the movement of residual moisture are suppressed, which is extremely effective in improving durability. Furthermore, condensed phosphates are said to have an air-entraining effect, which increases the porosity of refractory materials.
By using granular phosphate, which is one of the causes of a decrease in strength, the amount of phosphate added can be kept to the minimum necessary limit, which also contributes to improving durability.

On the other hand, in spray-resistance materials, a basic aggregate is usually mixed with alkali metal salts such as orthophosphoric acid, polyphosphoric acid, metaphosphoric acid, and ultraphosphoric acid as a binder, and calcium compounds such as calcium carbonate, quicklime, and slaked lime as binding aids. It is blended, and when used, water is added to form a slurry, which is then sprayed onto the repaired area hot or cold, allowing it to adhere and harden. In this case, the phosphate reacts with the calcium compound in the slurry, and the heat received after spraying forms a Na, 0-Ca0-P, O, system connective tissue that firmly adheres to the repaired surface and forms a fire-resistant pound. generate. In general, the conditions for improving the durability of spray repair materials include high viscosity of the slurry, fast curing reaction, high adhesion to the repaired surface, high pound strength and low peeling due to explosion phenomena. . Phosphate added as a binder generally has a peptizing effect, which works effectively in caster pull refractories, but in spray materials it suppresses the increase in slurry viscosity and causes a decrease in adhesion. . For this reason, when highly reactive slaked lime is used as a bonding aid, the viscosity of the slurry increases, but on the other hand, if unreacted slaked lime remains, another problem arises in that it tends to explode and flake off after forming pounds. However, the use of granular phosphate according to the present invention increases the viscosity of the slurry and improves the adhesion to the repaired surface compared to the conventional mixture of powdered phosphate, and at the same time, the explosion phenomenon associated with the use of slaked lime increases. It has been found that, more surprisingly, the hot strength of the pound is increased, a highly refractory connective tissue is obtained, and the durability is greatly improved.

This is because conventional powdered phosphates have properties such as hygroscopic solidification or easy solidification during slurry formation, so they have poor solubility in refractory slurry, and are therefore used as binding aids. The curing reaction due to binding with calcium compounds is insufficient, making it difficult to increase the slurry viscosity, whereas granular phosphate dissolves quickly in the slurry and the curing reaction progresses, resulting in an increase in the slurry viscosity. It is thought that the adhesion of the repaired surface will be increased, and even if slaked lime is used as a binding agent, there will be less unreacted residual slaked lime, and flaking due to explosion will be reduced.

A further advantageous and effective advantage of the present invention is that connective tissues with extremely high refractory properties are obtained, due to the high reaction rate between phosphate and calcium agents, which reduces the CaO content in the connective tissues. This is thought to be due to the increase in the temperature and the formation of high-melting point compounds.

In other words, in dolomite-based and magnesia-based spray-resistant materials that use ordinary phosphate as a binder, Na, 0-C
a0-P, Ot system, cao-P, Oa system, Ca0-P,
Connective tissue such as O,-Siα system is formed, but in both cases, the higher the CaO content, the higher the melting point (1700℃~1900T)
:) is known to form a highly refractory connective tissue, and because conventional powdered phosphates have low solubility and a low reaction rate with calcium agents, low melting point ( 1
It is estimated that a large amount of the composition with a temperature of 400° C. or lower) is produced, which lowers the fire resistance. In conventional steelmaking furnaces, the tapping temperature is usually below 1,660°C, but recently steel has been tapped at temperatures of 1,700°C or higher, and the present invention has the significance of this invention as the demand for high refractory properties has risen to 1. There is a big one.

In addition, in the case of spray materials, as with castapul, granular phosphate can be added in a small amount to obtain an effective concentration, so the amount of compounded material can be greatly reduced, reducing the furnace material consumption rate and adding it to molten steel. This also results in higher quality steel due to the reduction in phosphorous pickup.

As described above, the monolithic refractory containing granular phosphate according to the present invention is significantly superior to conventional refractories containing powdered phosphate in terms of storage stability, workability, and high fire resistance. In addition, it can be said that it is an extremely excellent product that can contribute to reducing the cost of furnace materials and improving the quality of steel.

The monolithic refractory containing the granular phosphate of the present invention can be used as any commonly used composition.

For example, in caster pull refractories, refractory aggregates include high alumina aggregates such as sintered alumina, bauxite, TM alumina, banded shale, and synthetic mullite, and acidic aggregates such as clayey chamotte, zircon, waxite, and kyanite. , basic aggregates such as dolomite, magnesia, carbon, legalized silicon, etc. As alumina cement, No. 1 cement,
In addition to No. 2 cement, super alumina cement, etc., high alumina, refractory ultrafine powders such as zircon, and silica, and clays such as kaolin, Kibushi clay, and Frogme clay can also be blended.

The amount of granular phosphate is usually 0 per 100 parts by weight of refractory aggregate, alumina cement, refractory ultrafine powder, clay, etc.
The amount is about 0.01 to 1 part by weight, but is not particularly limited.

In addition, for spray refractories, basic aggregates such as magnesia clinker and dolomite clinker, and non-basic aggregates such as zircon, alumina, sillimanite, mullite, silica stone, and waxite are combined as refractory aggregates. Quicklime as an auxiliary agent,
Slaked lime, calcium carbonate, calcium bicarbonate, etc. can be used, and a typical composition consists of 100 parts by weight of refractory aggregate, 1 to 10 parts by weight of a binding aid, and 1 to 10 parts by weight of granular phosphate. Although the above description has been made regarding caster pull and sprayed materials, the present invention is not particularly limited to these, and can be applied to any monolithic refractories containing phosphates as deflocculants or binders. I can do it.

Next, the effects of the present invention will be specifically explained by comparing and presenting various data regarding Examples and Reference Examples.

・Castaple refractories Knead the composition shown in Table 1 and make 35 x 35 x 1
Hook it into a 50 tjl mold, remove it after hardening and make it 110
It was dried at ℃ for 20 hours. 100℃ and 1500℃ after drying
The lost porosity and compressive strength were measured after firing.

Further, hot bending strength was measured at 1400°C after drying. The measured values are shown in Table 2.

・For the sample compositions shown in Table 3, the slurry viscosity was measured, the adhesion of the obtained refractories and the presence or absence of explosion were observed, and the hot bending strength was measured, and the results are shown in Table 4. .

・Adhesiveness, explosive 1! Made of magnesia brick with a thickness of 30n, 150fl square, depth 1
000 test furnace was built and 15
The temperature was raised to 00°C, the converter slag was introduced, and it was melted to coat the inside of the test furnace with a slag layer. This is 1250'C
Apply the sample slurry quickly with a hand scoop while holding the sample slurry. After observing the adhesion of the sprayed material and the presence or absence of explosion, the temperature was rapidly raised to 1600°C and held for about 1 hour, and the adhesion status during the heating process and holding time was observed.

Furthermore, the same observation was made at 1750°C.

- Hot bending strength was measured at 1400°C.

Table 2 Table 3 Table 4 Notes a) All numerical values in Tables 1 and 3 represent parts by weight.

Note: The phosphates used in Tables 1 to 4 are solid phosphate salts for Examples and powder phosphate salts for Comparative Examples.

Note ■ 0 indicates good, Δ indicates somewhat good, and X indicates poor.

Claims (3)

[Claims] (1) A monolithic refractory containing phosphates as a compounding component, characterized in that the phosphates are in the form of granules. (2) Spray repair refractories and caster pull refractories containing granular phosphates as a compounding component. (3) The refractory according to claims 1 to 2, wherein the phosphates are one or more selected from alkali metal salts of ortho, poly, meta, and ultraphosphoric acids.