JPS591234B2 - Basic spray refractory composition - Google Patents

Description

[Detailed description of the invention] The present invention applies to steelmaking furnaces such as converters and electric furnaces, ladles, RH,
The present invention relates to an improvement in a basic spray composition for dry hot repair used for repairing snorkels and the like of degassing devices such as DH.

In recent years, hot spraying repair has become essential for various types of steelmaking furnaces, ladles, and other furnaces.

The dry hot spray repair material (hereinafter simply referred to as spray material) currently mainly used in converters etc. is a spray agent that adds water at the tip of the nozzle to form a slurry that adheres to the required area and repairs. .

Conventionally, spraying materials using phosphate as a binder have been mainly used in converters and have been effective, but recently the operating temperature in converters has been changing to higher temperatures due to the legacy of the CE ratio, increased degassing treatment, etc. As a result, sprayed materials using conventional binders are no longer able to provide sufficient durability.

Conventional spray materials using sodium phosphate as a binder use magnesia clinker and synthetic dolomite or natural dolomite clinker as aggregates, and add coal salts (CaCOs,
Ca(OH)2, etc.) is used as a binding aid, and sodium phosphate salts (sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, acidic sodium metaphosphate, monosodium phosphate, etc.) are added as binding agents. It is something that exists.

The concept behind this conventional spray material is as follows.

In other words, sodium phosphate salt and lime salt are used to improve the adhesion of the sprayed material to obtain a certain slurry viscosity, and upon receiving heat, rapidly form a Na20-Ca0-P205 connective tissue. It is possible to obtain strength and volumetric stability in hot conditions, and dolomite as an aggregate further increases hot strength and hot volumetric stability, and prevents slag from penetrating into the sprayed material, increasing durability. This is a waste that can be improved.

However, there are various factors involved in adhering the sprayed material and making it durable, but it can be said that the most important factor is the selection of the binder.

Conventional spraying materials using sodium phosphate have become insufficient in terms of durability in steelmaking furnaces, where high-temperature steel tapping is being used.

In other words, conventional spraying materials mainly use sodium phosphate, especially sodium hexametaphosphate, but this sodium hexametaphosphate is known as a deflocculant for MgO, clay, etc., and is a necessary slurry for spraying materials. The viscosity cannot be sufficiently increased, and as a result, adhesion is insufficient, and the adhesive surface tends to become unstable due to rapid evaporation of moisture on the adhesive surface during adhesion, resulting in insufficient adhesive strength.

In addition, sodium phosphate reacts with lime salt and receives heat, forming a Na20-Ca0-P2O3-based connective tissue in the sprayed material, which provides hot strength and hot volume stability. As the bonding strength becomes insufficient under harsher operating conditions, such as increased heat and extended blowing time, the bonding strength is washed away by molten steel and slag, resulting in reduced durability compared to when used under comparatively gentle steelmaking conditions. .

Therefore, stabilizing the adhesive surface, improving adhesive strength, and further improving hot strength will lead to improved durability, and it is important to improve the connective tissue of the sprayed material by selecting a binder.

The spray material of the present invention improves the above points, and replaces the conventional sodium phosphate salt with potassium phosphate, partially or mostly, as a binder, and converts the connective tissue into 2O-Na20-
It is a Ca0-P2O3 system.

The use of potassium phosphate salt has already been proposed by the present inventors, for example, in Japanese Patent Publication No. 53-37363.
In the publication, clays 1 to 3 using magnesia as an aggregate and a plasticizer.
We proposed a mixture of sodium alginate, ammonium alginate, 0.01-0.1% by weight, dipotassium phosphate, potassium pyrophosphate alone or a mixture of both, and trisodium phosphate, 1-10% by weight. However, the 2ONa20S102-P2O3 type connective tissue has low hot volume stability at temperatures of 1680° C. or higher and extremely low strength.

Furthermore, JP-A No. 50-49311 describes a spraying material containing phosphates and/or silicates of alkali metals or alkaline earth metals and calcium salts, but there are no specific examples of the use of potassium salts. I can't find it.

JP-A No. 49-99109 discloses that phosphate is
5.5%, plasticizer 0-5% lime source CaO 0
．． It is described that the spraying material consists of 1 to 7% and the rest is basic aggregate, and that a water-soluble alkali metal bexametaphosphate is used as a binder, but sodium hexametaphosphate has the disadvantages as mentioned above. Furthermore, potassium metaphosphate is hardly soluble in water and becomes water-soluble unless it is a strong alkaline solution containing dissolved Na2O, making it impossible to use it as a binder in this fire-resistant composition.

The spraying material of the present invention uses 1 magnesia clinker, 1 synthetic dolomite clinker, 1 natural dolomite clinker as an aggregate.
Using natural lime clinker and Ca as binding aid
CO3 or Ca(OH)2 is used in an amount of 2 to 10% by weight.

To this, at least one of a sodium phosphate salt and a sodium silicate salt and a potassium phosphate salt are added as a binder in a total amount of 2 to 8% by weight of a potassium phosphate salt, a sodium phosphate salt, and a total amount of 0.1 to 8% by weight. A basic spray-on refractory composition with added sodium silicate salt in an amount of 2.0% by weight.

The potassium phosphate salt as a binder used in the present invention has a pH of
is preferably on the acidic side, and monopotassium phosphate, potassium metaphosphate, and potassium acid pyrophosphate are preferred.

It is not preferable to use a potassium phosphate salt on the alkaline side because it tends to cause the deposits to explode during spraying.

Potassium metaphosphate is insoluble in water, but when used in combination with a small amount of sodium silicate, it becomes soluble in water and becomes very sticky, making it suitable as a spray bonding agent.

These pH values are on the acidic side, and potassium phosphate increases the slurry viscosity of the sprayed material more than sodium phosphate, so the adhesive surface of the sprayed material is stabilized, the adhesive strength is high, and color melting increases as it reacts with the aggregate. It has very important properties for sprayed materials, such as improved hot strength.

However, if potassium phosphate salt is used in an amount of 4% by weight or more, it reacts quickly with lime salt and magnesia and hardens without being able to obtain an appropriate slurry viscosity, resulting in a dry state and reduced adhesion of the sprayed material.

Therefore, by adding a small amount of sodium silicate salt, curing can be delayed while maintaining high viscosity, and adhesiveness can be improved.

As the binder used in the present invention, sodium phosphate salts that can be used in combination with potassium phosphate include sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, acidic sodium metaphosphate, and monosodium phosphate.

In addition, sodium silicate salts include No. 1 sodium silicate, No. 2 sodium silicate,
No. 3 sodium silicate, No. 3 sodium silicate, sodium metasilicate, and sodium orthosilicate are preferred.

The above binders can be used alone or in combination of two or more.

Alkali from the binder in the spray material 20/'Na2
It is desirable that the weight ratio of 20 to O+ is within the range of 0.05 to 0.95.

When the K20/N a 20 + K20 merization is less than 0.05, there is no difference in hot strength and adhesive strength compared to conventional phosphoric acid (l-I) lamb salt, and there is no improvement in durability.

If it exceeds 0.95, the slurry viscosity of the spray material will increase,
This is undesirable because it tends to clog inside the nozzle during spraying.

Therefore, the amount of acidic potassium phosphate and sodium phosphate added as binders is preferably 2 to 8% by weight, and 2% by weight.
If it is less than 8% by weight, the adhesion will be poor, and if it exceeds 8% by weight, the durability will be reduced.

As a dissolving agent for potassium metaphosphate, sodium silicate salt is required in an amount of 0.1 to 2.0% by weight, but if it exceeds 2% by weight, it is not desirable because the hot strength decreases due to 5i02 in the sodium silicate salt.

Lime salts (CaCO3, Ca(a()) as binding aids
2) is not preferable because if it is less than 2%, it becomes difficult to instantaneously form connective tissue and the adhesion is deteriorated, and if it exceeds 10%, the spray material becomes porous and its durability is reduced.

The sprayed material obtained in this way is entangled with the dolomite aggregate and lime clinker, and the Ca of the entire sprayed material is
o/P 20=, +S t 02 weight ratio 0.5 to 3
．． If it is within 5, the hot strength will be high and the durability as a spray material will increase, so it is desirable to adjust the blending amount of dolomite clinker 1 lime clinker.

Examples of the present invention will be described below.

Table 1 shows the chemical components of the refractory aggregate used in the present invention.

Example I An example of use in the snorkel part of a pH degassing device manufactured by Company A is shown.

The inside of the snorkel of the pH degassing device is abraded and locally damaged by the flow of molten steel caused by stirring of argon gas.

Although the temperature of molten steel is low at about 1570 to 1650°C, the molten steel is subject to strong abrasion, and a spray material with high hot strength is required.

The conventional product had a breaking bond rate of 75% and the durability was about 3 cycles, but the breaking bond rate using the invention products I and ■ was 85%.
%, and the durability was recognized as 4 charges and 5 charges, and overall, the spraying consumption rate was reduced by 20% and 25%, and the spraying frequency was reduced, resulting in labor savings.

Example 2 Company B's converter has a high average operating temperature of 1,680°C, and a temperature of 1,700°C.
Nearly 30% of the cases involve high-temperature blowing at temperatures above ℃.

In this converter, when products ① and ② of the present invention were used, they adhered well to the furnace wall at 1300°C immediately after the slag was discharged, with 75% and 80% adhesion, respectively.
% adhesion rate (by visual inspection) is 60 to 70% of conventional products.
It was better than

As for durability, the average durability at n=10 was visually observed and the residual rate (remaining area ratio) was good as shown in Table 3 below.

Claims (1)

[Claims] I A basic spray-on fireproof composition containing CaO, at least one of a sodium phosphate salt and a sodium silicate salt and a potassium phosphate salt as a binder, and a coal salt as a binding aid. Basic spraying characterized in that the total amount of the potassium phosphate salt and the sodium phosphate salt is 2 to 8% by weight, and the sodium silicate salt is 0.1 to 2.0% by weight. Fireproof composition. 2 The alkali weight ratio in the basic sprayed fireproof composition is 20/
The basic spray-on fireproof composition according to claim 1, wherein 20 in Na2O+ is 0.05 to 0.95. 3. The basic spray-on fireproof composition according to claim 1 or 2, wherein the potassium phosphate salt is monobasic potassium phosphate, potassium metaphosphate, or potassium acid pyrophosphate.