JPH01224274A - Refractory composition for spraying - Google Patents

Abstract

PURPOSE:To prevent the substrate from blasting, by adding a fibrous material which is dissolved in water, when the substrate is heat-dried or exposed to high temperature, to a refractory composition in which the crude particles and the fine particles are separately fed to the spraying nozzle at a specific ratio. CONSTITUTION:The subject refractory composition is composed of (A) the crude particle fraction comprising 100pts.wt. of crude refractory particles of 3mm-74mu sizes, 0.05-1.0pt.wt. of a fibrous material soluble in warm water over 50 deg.C, of 0.1-20mu diameter and 1-5mm length and 0.1-1.5pt.wt. of a curing agent, and of (B) the fine particle fraction comprising 100pts.wt. of the refrac tory particles of less than 74mu sizes, a colloidal silica solution of 20-30wt.% solid content and water in a slurry form. The crude particles are directly, the fine particles are made into a slurry on site, then they are separately forced to the nozzle where they are mixed at a prescribed ratio and sprayed to the substrate. When sprayed substrate is heated, and the temperature exceeds 50 deg.C, the fibrous material is dissolved in water and colloidal silica dispersion, until it dissipates and air-permeating pores are formed to inhibit blasting.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention separately supplies a coarse particle portion and a fine powder portion to a spray nozzle,
Mixing and spraying in the nozzle, so-called slurry spraying, relates to new refractory compositions for use in construction.

[Prior art] In recent years, the construction of linings for molten metal containers (ladles, tie dishes, gutters, etc.) has changed from brick lining construction to casting construction using monolithic refractories. Due to the complexity and other concerns, spraying construction is increasingly being used.

However, spraying construction has the drawback that, because the filling density of the construction body is low, corrosion resistance is low, especially in the slag line portion, and the life is short.

In order to improve the above-mentioned drawbacks, the present inventors
By completing the "Construction Method for Fireproof Composition for Spraying Application" described in the ZT754 publication, it became possible to obtain a construction body with a high packing density, and it came to be widely adopted. According to this method, [a curing agent is added to the particle size-adjusted refractory aggregate of 74 μm or more, a deflocculant is added to the fine powder portion of 74 μm or less, and the fine powder portion of the particle size of 74 μm or less is mixed with a liquid. A method for applying fire-resistant compositions for spray construction, which consists of making slurry with a binder, supplying each slurry separately to a spray nozzle, mixing the two at the nozzle, and spraying. reduced,
By using so-called alumina-free spraying material, it has become possible to perform spraying construction with quality (characteristics) equal to or better than vibration molding or pouring construction even with a low moisture content.

[Problem to be solved by the invention] However, as the packing density of the spray material increases, drying and
When the temperature rises, the moisture in the construction object does not dissipate from the surface, and the water vapor stays inside, eventually breaking the surface of the construction object and protruding, causing a so-called explosion. If used as is, it may cause local damage during operation. This has led to problems such as the lifespan being significantly reduced, or if the explosion is large, it is necessary to interrupt the temperature rise and perform spraying work (repair) again.

On the other hand, conventionally there has been a technique of adding inorganic fibers or organic fibers to the spray material, but this was only for the purpose of reducing ribbon loss and was ineffective in preventing explosions.

In addition, a similar technique is described in Japanese Patent Application Laid-open No. 10079/1981 [Vinylon is used for 100% by weight of a refractory aggregate containing 2 to 25% by weight of ultrafine powder with a particle size of 5μ or less and a binder. , nylon, polyvinyl, polyester, polyethylene, polypropylene, etc., which melts or decomposes at 200°C or lower, in an amount of 0.01 to 1.0% by weight. melts or decomposes due to heat, and the technical concept of spraying during drying and heating is completely different from the purpose of the present invention, which is to prevent explosions of construction objects.

[Means for Solving the Problems] The present inventors found that in order to prevent the above-mentioned explosion, it is sufficient to form ventilation gaps that serve as evaporation paths for moisture before the start of drying, and conducted various research. As a result, we have completed a fire-resistant composition for spray construction that contains a fibrous material that dissolves in the added water whose temperature increases when the construction body dries and the temperature rises.

That is, the present invention provides a fire-resistant composition for spraying, in which a coarse particle part and a fine powder part are separately supplied to a spray nozzle, and mixed at a predetermined ratio in the nozzle for spray construction. 100 parts by weight of coarse particles with a particle size of 3+em to 74μ of the raw material,
A warm water-soluble fibrous material with a diameter of 0.1-20μ, a length of 1-5I, and a water solubility temperature of 50"C or higher, 0.05-1.
0 parts by weight, and 0.1 to 1.5 parts by weight of a curing agent;
And the fine powder part is a fine powder of refractory raw material with a particle size of 74μ or less 100
The present invention relates to a fire-resistant composition for spraying, characterized in that it is a slurry consisting of a colloidal silica liquid and water having a solid content of 20 to 30% by weight.

[Function] The fireproof composition for spraying construction of the present invention (hereinafter simply referred to as spraying material) will be explained below.

The refractory raw materials used in the present invention include silicic acid raw materials such as silica sand, silica stone, and lowite, fused alumina, calcined alumina,
High alumina raw materials such as bauxite and pansoil shale, conventional raw materials such as silicon carbide, magnesia raw materials, zirconia and zircon can be used depending on the intended construction body.

Coarse particles of refractory raw materials are obtained by crushing and sifting raw materials selected from the above raw materials by a conventional method, and generally
Plow theory refers to particles in the particle size range of 74μ, but as the sieve fraction is an unavoidable component, fine particles of 74μ or less also account for approximately 20% of the total coarse particles.
The fine powder of the refractory raw material, which may be contained in an amount of about 20% by weight, is generally in the particle size range of 74μ or less, but for the same reason as the coarse grain part, the coarse particles of 74μ or more are about 20% by weight of the entire fine powder group. It can be contained up to about %.

The coarse particles and fine particles of the refractory raw material may be used in combination of two or more of the above raw materials whose particle sizes are adjusted within the above range depending on the use and purpose of the construction body.

The coarse particle portion of the spray material of the present invention further contains a fibrous substance soluble in hot water. The fibrous material has a diameter of 0.1 to 20μ.
The length must be 1 to 5 mm, and the dissolution temperature in water must be 50° C. or higher.

If the diameter of the fibrous material is less than 0.1 μm, the ventilation voids formed as described below are too small to allow water vapor to move or dissipate during drying and heating. If it exceeds , the ventilation voids become too large and the structure of the constructed body becomes porous, resulting in a decrease in corrosion resistance.

In addition, if the length of the fibrous material is less than 11 μm, ventilation voids cannot be formed continuously, and movement and dissipation of water vapor is difficult to occur, and if the length exceeds 5I, the added fibrous material becomes entangled with each other. Difficult to distribute evenly during spraying.

Furthermore, the dissolution temperature of the hot water-soluble fibrous substance in water is 50°C.
If it is less than that, it will dissolve in water immediately after spraying, and the part occupied by the fibrous material will be filled with the fine powder part of the refractory raw material, making it difficult to form ventilation voids as desired. I can't.

As the above-mentioned hot water-soluble fibrous material, organic or inorganic materials such as commercially available polyvinyl alcohol fibers for paper making or cellulose fibers can be blended. The amount of the fibrous material added is 0.05 to 0.5 parts by weight per 100 parts by weight of coarse particles of the refractory raw material. If the amount added is less than 0.05 part by weight, there will be few ventilation voids formed in the construction body, and the explosion prevention effect will be low; if it exceeds 0.5 part by weight, the structure of the construction body will become too porous. , corrosion resistance decreases.

Further, a curing agent is added to the coarse grain portion. As a hardening agent, commercially available sodium silicate (powder), potassium silicate, slaked lime powder,
Magnesium chloride or the like is added in an amount of 0.1 to 1.5 parts by weight per 100 parts by weight of coarse particles of the refractory raw material. If the amount of the curing agent added is less than 0.1 part by weight, the curing speed of the spray material will be slow and the adhesion rate will be reduced. Moreover, if it exceeds 1.5 parts by weight, the curing speed is too fast and the nozzle may be clogged, making spraying impossible.

As described above, the coarse grain portion of the spray material of the present invention is composed of the coarse grains of the refractory raw material, the hot water soluble fibrous material, and the hardening agent.

Next, colloidal silica liquid is added to the fine powder portion of the spray material of the present invention. Commercially available colloidal silica liquid has a solid content of 20~
10 to 30 parts by weight of 30% by weight is blended per 100 parts by weight of fine powder of refractory raw material. If the amount of the colloidal silica liquid is less than 10 parts by weight, the solid content will be low and the strength of the constructed body will be reduced. Moreover, if it exceeds 30 parts by weight, the water content will be too large as a whole, and the constructed body will become porous and its strength will decrease.

During construction, 0 to 10 parts by weight of water is further added to the fine powder part prepared as described above as a remainder of the construction water content, and the fine powder of refractory raw material with a water content of 15 to 25% by weight and colloidal silica are added. It is provided as a slurry. In addition,
If the amount of water in the colloidal silica liquid alone can cover the amount of water in the application, there is no need to add additional water.

When applying the spray material of the present invention, the coarse particle portion is mixed in advance at a predetermined ratio, and the coarse particle portion is fed into a spray device equipped with a feeder motor called a so-called spray gun, and is supplied to a nozzle through a material hose. be done.

On the other hand, at the construction site, the fine powder part is made into a slurry by putting fine powder of refractory raw materials, colloidal silica liquid, and water in a predetermined ratio into a slurry unit, and the slurry is fed under pressure to the nozzle through the slurry hose. A desired construction body can be formed by uniformly mixing the powder and the fine powder part at a predetermined ratio, and the resulting mixture is ejected from a nozzle.

Note that the ratio of coarse particles to fine particles can be varied depending on the size and shape of the construction object, but it is usually 50%.
:50 to 75:25, preferably about 70:30.

Further, in order to adjust the curing speed of the construction body, the blending ratio of the curing agent and the colloidal silica liquid can be changed as appropriate.

When the construction body obtained from the sprayed material of the present invention as described above is heated at a temperature increase rate of about 1°C per minute according to a conventional method, fibrous substances at a temperature of 50°C or higher are dissolved from the heated surface of the construction body. The fibrous material from the part that reaches a temperature higher than that temperature releases water and/or
Alternatively, it dissolves and disappears in the colloidal silica liquid, and then fine ventilation voids are formed. As the portion of the fibrous portion within the construction object reaches the melting temperature moves, ventilation voids are sequentially formed within the construction object, and eventually are formed over the entire construction object. Since the water vapor generated inside the construction body passes through the formed ventilation gap and is released to the outside, an explosion phenomenon can be prevented.

[Example] The spray material of the present invention will be further explained below with reference to Examples.

E11 Mix the coarse particle part and the fine powder part in the proportions listed in Table 1 below, and feed the coarse particle part to the spray nozzle at a speed of about 20 ky/min, while the fine powder part is By supplying the powder to the nozzle at a high speed, mixing the coarse particles and fine particles in the nozzle, spraying, and drying at 110°C for 24 hours.
A specimen for physical property testing with dimensions of 00-plow x 40 mm x 160 mm was obtained.

In addition, the specimen for the explosion resistance test was a 6Qmm x 60mm x 60mm constructed body obtained by carrying out blow-up construction in the same manner as described above.
After being left for a period of time, the samples were placed in an electric furnace maintained at a predetermined temperature listed in Table 1, and those that exploded in 30 minutes were graded "X" and those that did not explode were graded "O".

The characteristics of the specimen are also listed in Table 1.

[Effects of the Invention] As detailed above, the spraying material of the present invention is used when applying the separately prepared coarse grain part and fine powder part to the same nozzle. By adding a hot water-soluble fibrous substance that dissolves in hot water of 50℃ or higher to the granules, extremely small ventilation voids are formed when the construction object is dried, and the construction object will not explode even if it dries rapidly or the temperature rises. Especially in newly constructed furnaces, the drying and preheating period can be shortened to about 30% compared to conventional methods, which is extremely useful for energy saving and does not reduce corrosion resistance during use.

Further, the spray material of the present invention can be used for repairing various refractories as well as conventional spray materials.

Patent applicant Shinagawa White Brick Co., Ltd.

Claims (1)

[Claims] In a refractory composition for spraying, in which a coarse particle portion and a fine powder portion are separately supplied to a spray nozzle, and mixed at a predetermined ratio in the nozzle for spray construction, the coarse particle portion has a particle size of 3 of the refractory raw material.
100 parts by weight of coarse particles of mm to 74μ, diameter 0.1 to 20μ
, 1 to 5 mm in length, 0.05 to 1.0 parts by weight of a hot water soluble fibrous substance with a water dissolution temperature of 50°C or higher, and 0.1 to 1.5 parts by weight of a hardening agent; and the fine powder part is fireproof. 100 parts by weight of fine powder with a particle size of 74μ or less, solid content 20
A fire-resistant composition for spraying construction, characterized in that it is a slurry consisting of ~30% by weight of colloidal silica liquid and water.