JPS5934674B2 - Basic refractory composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a basic refractory composition, and more particularly to a basic refractory composition using a raw material containing a large amount of lime, such as limestone or magnesite.

Limestone is abundantly produced as a resource and is therefore inexpensive, and is used for various purposes, but especially CaO is used as a raw material for refractories.
is very attractive because it has a very high melting point of 2625°C and a low vapor pressure at high temperatures.

However, it has the disadvantage that it is difficult to use due to the strong digestibility of CaO.

For solutions to prevent digestion of lime (Cab), please refer to Fe
2O31Al 203 + T 102 + S 10
2 + Cr 2o3 lMgO and other oxides are mixed with lime (
Coating or adding Ca0) to stabilize it,
A method for producing lime clinker for producing an electrolyte product of lime (CaO) has been proposed.

Magnesium lime is already widely used in refractories as semi-stabilized dolomite clinker, which is obtained by coating or adding Fe2O3 and then firing at a high temperature.

However, few attempts have been made to produce refractories using raw materials of limestone or magnesia.

For example, Japanese Patent Publication No. 47-47 related to some inventions of the present inventors.
In Publication No. 962, magnesia clinker 95
A method for producing an unfired basic refractory brick, characterized in that fine powder of dolomite ore or limestone containing lime, which is not subjected to combustion treatment, is blended as CaO in a ratio of 2 to 20 parts by weight to 70 parts by weight. However, when the limestone content exceeds 20% by weight as CaO, CaCO is removed during heating.
3 → When decomposing into CaO + CO2, CO gas is generated and shrinks significantly during the sintering process, so it has the disadvantage of reducing the volume stability in hot conditions, which is important for pouring refractories, so it should not be used in large quantities. was not possible.

In view of the above drawbacks, the present inventors conducted various studies and found that CaO
It has been found that when silicates and/or phosphates react with each other, a bond with a high melting point is formed, and this forms a skeleton that can suppress heating shrinkage of limestone or magnesia limestone.

The present invention was made based on such knowledge, and the main object of the present invention is to provide a basic fireproof composition that uses raw materials of limestone or magnesium limestone and has good volume stability, heat resistance, and durability. This is what we are trying to provide.

Another object of the present invention is to provide a basic refractory composition that has excellent durability against molten steel in steelmaking furnaces, tundishes, etc., and is also effective as a slag-forming agent.

The first invention of the present invention provides at least 35 parts by weight or more of at least one of limestone and magnesia limestone.
100 parts by weight of an aggregate part consisting of less than 0.00 parts by weight and the balance consisting of one or more types selected from magnesia clinker, dolomite clinker, and dolomite brick waste;
No. 33 of the present invention, which is a basic fire-resistant composition characterized by comprising ~10 parts by weight of at least one binder selected from silicate and phosphate, and 3-7 parts by weight of a thickening plasticizer. Invention No. 2 provides at least 35 parts by weight of at least one of limestone and magnesium limestone.
100 parts by weight of an aggregate part consisting of less than 0.00 parts by weight and the balance consisting of one or more types selected from magnesia clinker, dolomite clinker, and dolomite brick waste;
A basic refractory characterized by comprising ~10 parts by weight of at least one binder selected from silicates and phosphates, 3 to 7 parts by weight of a thickening plasticizer, and 5 to 30 parts by weight of fluorspar. It is a composition.

Although the composition of the present invention is in the form of a powder, it can also be used by molding it into a brick by a commonly used means.
It can also be used as a spray material or coating material in the form of a monolithic refractory.

Next, the present invention will be described in detail with reference to examples of sprayed materials and coating materials for monolithic refractories to which the present invention is particularly effective.

A feature of the present invention is the addition of silicates or phosphates to limestone or magnesia.

The blending ratio of magnesia clinker to limestone is 0 to 6.
Curve showing the relationship between the linear change rate after heating at 1500°C for 2 hours in the range of 5 parts by weight and 5 parts by weight of the binder of the present invention and in the case of not adding the binder of the present invention. is shown in the drawing.

The drawing shows 1500% of the fire-resistant aggregate according to the present invention in which the blending ratio of limestone is 100 to 35 parts by weight and the blending ratio of magnesia clinker is 0 to 65 parts by weight, with and without the binder of the present invention. It is a curve diagram showing the relationship between the linear change rate after heating for 2 hours at °C, and all samples were 50 parts by weight of particles with a particle size of 5 to 0.5 mm, and 50 parts of particles with a particle size of less than 0.5 mm.
This figure shows the results of a test conducted using a molded product having a size of 50 mm x 50 mm by blending it in the proportion of parts by weight.

In the drawings, 1 shows the results without the binder according to the present invention, 2 shows the results when 5 parts by weight of No. 2 sodium silicate was added, and 3 shows the results when 5 parts by weight of sodium hexametaphosphate was added.

From the drawing it is clear that:

It is clear that the heating volume stability of Samples 2 with silicate added and 3 with phosphate added is superior to the volume stability of 1 with no binder added.

In other words, CaO produced by heating from limestone reacts with silicate or phosphate to form β-2CaO-8iO2,3.
CaO・5i02 or 3Ca()P2O5 or 2.4
Ca() 0.6Na20/P2O5-based high-melting bond is formed, which acts as a skeleton and suppresses the shrinkage of unreacted CaO, so the structure has little shrinkage and shrinkage cracks even when heated to high temperatures. There is.

As raw materials for limestone and magnesia limestone that can be used in the present invention, almost any commonly produced limestone can be used.
It is preferable that there are few impurities such as e2O3 and Al2O3 that react with CaO and form low-melting substances.

Also, limestone, magnesite limestone and magnesite (MgCC)
It is also possible to add a small amount of 3).

Note that limestone and magnesium can be mixed or used alone, but the moisture resistance and slag-forming agent effect will be improved if the limestone is closer to limestone.

On the other hand, if it approaches magnesian limestone alone, the erosion resistance will improve, so it can be mixed according to the purpose.

When magnesia clinker, dolomite clinker, dolomite brick chips, etc. are added to the formulation of the present invention, the erosion resistance becomes stronger.

However, on the other hand, if more than 65 parts by weight of magnesia clinker, dolomite clinker, dolomite brick chips, etc. are added, the slag infiltration becomes deeper and at the same time the slag-forming effect tends to decrease.

Moreover, if these are not added, there is no effect of improving the erosion resistance.

Therefore, the amount added is preferably 65 parts by weight or less depending on the application.

As binders used in the present invention, alkali metal silicates and phosphates have conventionally been used as binders for spray materials, but as mentioned above, they are necessary for the volume stability of limestone and magnesia. Examples of these salts include No. 1 sodium silicate, No. 2 sodium silicate, No. 3 sodium silicate, sodium metasilicate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium pentapolyphosphate, sodium hexametaphosphate, and ammonium phosphate. and so on.

Note that it is also possible to mix phosphate and silicate or use them alone.

Although phosphates have excellent hot strength, they are also expensive and may be subject to strict regulations depending on the type of steel.

Silicates are inexpensive and common binders, so they can be prepared depending on the application.

The amount added is 1 to 10 parts by weight per 100 parts by weight of refractory aggregate.
Parts by weight can be used.

If it is less than 1 part by weight, the troweling workability and spraying workability will be insufficient, the rebound loss will be very large, and the adhesive will also be easily peeled off.

If the amount exceeds 10 parts by weight, the volumetric stability at high temperatures will decrease, and phosphates will start to have an adverse effect on molten steel, and the cost will also increase, which is not preferable.

The thickening plasticizer used in the present invention includes generally known clay, calcium hydroxide, bentonite, methylcellulose, etc.
It is desirable to add 7 parts by weight.

Below 3 parts by weight μ, the adhesion rate during spraying becomes poor.

Note that pitch or the like may be added to the refractory aggregate in advance to granulate it, and a means for improving durability may be added by carbon bonding.

Or use fluorite as a means to improve the effectiveness of slag-forming agents.
Less than 0 parts by weight may be added.

If it exceeds 30 parts by weight, the effect of the sludge forming agent increases, but the erosion resistance deteriorates, which is not preferable.

The raw material particle size of the basic fireproof composition of the present invention is preferably 5 to 0.5, which is the particle size used for ordinary spray materials and coating materials.
Tomo's coarse particles 40 to 80 parts by weight, fine powder less than 0.5 mrn 2
About 0 to 60 parts by weight is preferable.

The metallurgical furnace in which the product of the present invention is used is desirably a furnace that can be heated at least at a temperature higher than the decomposition temperature of limestone and magnesia limestone, or that can be preheated and dried to 1000'C or higher after construction.

Specifically, it is desirable to use it as a hot repair material for steelmaking furnaces such as LD converters and electric furnaces, or as a coating material for tundishes.

In addition, when used as a coating material for tandish, active CaO reacts with Al2O3 in molten steel, resulting in A1203-C
Since it is easy to generate aO-based reactants, alumina adsorption, dephosphorization,
It has the effect of improving steel quality such as desulfurization.

Furthermore, since limestone and magnesium limestone are used, there is an advantage that the basic refractory composition can be supplied at a lower cost than conventional products (about 1/2 to 1/3 of the price of conventional products).

The basic refractory composition of the present invention generates very active microcrystalline CaO or CaO-MgO when heated, so it is easily eroded away by Fe-oxides in slag. The sludge-forming effect of dephosphorization and desulfurization is expected to increase quickly.

In addition, while conventional sprayed converter materials mainly suffer from peeling damage, the product of the present invention has less peeling damage due to the shallow penetration of silicate slag and is mainly caused by melting damage, but in terms of durability it is comparable to its father. Therefore, it is expected that the amount of slag forming agent used as a refractory will be reduced.

Next, the present invention will be specifically described with reference to Examples.

Formulations are in parts by weight.

Example I Table 1 shows the formulation and results of using 250 from Company A as a hot spray repair material in a converter.

The more limestone or magnesium there is, the more it is leached from the surface, but the peeling damage seen in conventional products was significantly less, and the durability was almost the same as that of conventional products.

Example 2 The results are shown when the coating material was used as a coating material for tandishes made by 0 companies.

As a result of preheating and drying at 1200° for 2 hours after trowel coating, the aluminum-killed steel was received without any surface cracks or peeling.

Table 2 shows the formulation of the coating material used and the results of use.

As a result, the slag line had considerable erosion loss, but
There was almost no erosion loss in the steel valleys, and adsorption of alumina was observed.

As a result of examining the quality of the steel in the mold, it was found that Al2O3 and S
There was a reduction in steel quality.

As described above, the refractory composition using limestone and magnesium limestone of the present invention has properties as a refractory material, slag-forming agent, and adsorbent properties.

[Brief explanation of drawings]

The drawings show the amount of magnesia clinker added and the heat shrinkage rate (with and without arrogance) in the basic refractory composition of the present invention, with or without magnesium clinker added to limestone, and with or without the binder of the present invention. It is a curve diagram showing the relationship. 1...Curve when the binder according to the present invention is not added;
2...Curve when 5 parts by weight of No. 2 sodium silicate is added, 3...Curve when 5 parts by weight of sodium hexametaphosphate is added.

Claims (1)

[Scope of Claims] 1. At least one kind selected from 35 parts by weight or more and less than 100 parts by weight of limestone and magnesia limestone, and the balance being one or more kinds selected from magnesia clinker, dolomite clinker, and dolomite brick waste. A basic material comprising 100 parts by weight of aggregate, 1 to 10 parts by weight of at least one binder selected from silicates and phosphates, and 3 to 7 parts by weight of a thickening plasticizer. Fireproof composition. 2. Aggregate part 100 consisting of at least 35 parts by weight or more and less than 100 parts by weight of at least one of limestone and magnesia limestone, and the balance being one or more selected from magnesia clinker, dolomite clinker, and dolomite brick waste. part by weight, at least one binder of silicate or phosphate in the amount of 1 to 10 parts by weight, 3 to 7 parts by weight of a thickening plasticizer, and 5 to 30 parts by weight of fluorite. basic refractory composition.