JPH10182251A - Non-slumping alkali silicate based bond castable composition and application method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-slumping, high density and low water content castable composition using a binder very small in age-hardening property to eliminate the limit of application working time and to provide the application method therefor. SOLUTION: This non-slumping castable composition is composed of a 1st component capable of forcibly feeding by pump, which is prepared by kneading 100wt.% solid matter consisting of 0.5-5wt.% alkali silicate, 3-20wt.% fluid assistant and the balance refractory aggregate and fine powder with water of the quantity enough to attain the consistency capable of forcibly feeding by pump, and a 2nd component of a flocculant, which is added into the 1st composition at the time of working. Further <=5wt.% clay is added into 100wt.% solid matter being the 1st component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel non-slump castable composition for use in a molten metal container, a molten metal processing apparatus, a cement kiln, an incinerator and the like.
The present invention relates to a method for applying the castable composition without using a mold or a formwork.

[0002]

2. Description of the Prior Art Portland cement-based wet spray compositions and methods of applying them are old and well known. For example, a mixture containing sand, gravel and Portland cement is made, kneaded with water to a pumpable consistency, and then the concrete is pumped into a nozzle. In this nozzle, a cement hardening accelerator and air are added, and the concrete material is sprayed on the surface, for example, the wall surface of the object to be sprayed. At that surface, the concrete hardens quickly enough to not slump from the sprayed surface. Such hardening is the result of the chemical accelerator accelerating with the Portland cement to initiate the hardening action rapidly, whereby the viscosity of the concrete rapidly rises to a level high enough to prevent slumping. To rise.

However, while this is suitable for applications such as civil engineering, refractory concrete is not used satisfactorily with Portland cement as a binder. This is because Portland cement cannot withstand the high temperatures and corrosive environments in which refractory materials are placed. Thus, the majority of refractory concrete, known as refractory castables, contains calcium aluminate cement rather than Portland cement. Calcium aluminate cements have much higher fire resistance and also have higher corrosion resistance to the environments found in high temperature refractory applications.

A castable composition for wet spraying using such a calcium aluminate cement as a binder and a method of applying the same are disclosed in JP-A-54-6100.
No. 5 is known. However, the composition disclosed in Japanese Patent Application Laid-Open No. 54-61005 contains calcium aluminate cement as much as 20% by weight, and the amount of water added is 10 to 20% by weight.
Therefore, the composition is inferior in corrosion resistance as a refractory material and mechanical properties at high temperatures. Then, U.S.A. S.
In Patent 5549745, non-slump property,
A castable composition of low moisture, low calcium aluminate cement is shown.

[0005]

Problems to be Solved by the Invention S. Patent
The castable composition of the non-slump, low moisture, low calcium aluminate cement shown in US Pat.
Although the material has sufficient properties as a refractory material, the first component gradually hardens after kneading with water because calcium aluminate cement showing hydraulic properties is used as a binder. In other words, after kneading with water, it exhibits self-hardening properties, so that the construction must be completed within a time period for maintaining the consistency in which the first component can be pumped. Therefore, since there is a limitation in the construction work time after kneading with water, not only must the first component be kneaded near the construction site, but it is not suitable for intermittent work or work requiring a long time. is there. Also, if the construction work has to be interrupted for a long time, the first component must be discarded. If the first component is hardened in the pump or the transfer hose, a great deal of damage will occur. Will occur.

[0006] An object of the present invention is to provide a non-slump, high-density, low-moisture castable composition using a binder having a very small self-hardening property and a method of applying the same, in order to eliminate the limitation of the working time. It is in.

[0007]

According to the present invention, there is provided a composition comprising 0.5 to 5% by weight of an alkali silicate, 3 to 20% by weight of a flow aid,
A pumpable first component obtained by kneading the remaining 100% by weight of solids composed of refractory aggregate and fine powder with water in an amount sufficient to achieve a pumpable consistency, and
A non-slump castable composition comprising a second component coagulant added to the first component during construction;
This is achieved by a non-slump castable composition in which no more than 5% by weight of clay is added to 100% by weight of the solids of the first component, and a method of applying those castable compositions.

[0008]

DETAILED DESCRIPTION OF THE INVENTION First of the castable composition of the present invention.
The ingredients consist of refractory aggregates, fines, alkali silicates, flow aids and sufficient water to achieve pumpable consistency and are kneaded. Further, the first component can be added with clay for the purpose of increasing non-slump properties during construction.

The refractory aggregate and fine powder may be any suitable refractory material for a molten metal container, a molten metal processing apparatus, a cement kiln, an incinerator and the like. Alumina, calcined alumina, bauxite, electrofused or synthetic mullite, sillimanite, andalusite, kyanite, ban shale, chamotte,
Loaite, silica, fused silica, electrofused or sintered magnesia,
Electrofused or sintered spinel, electrofused or sintered zirconia, zircon, chromite, electrofused or sintered magnesia-lime, electrofused zirconia-mullite, electrofused alumina-zirconia,
Examples include silicon carbide, silicon nitride, natural or artificial graphite, petroleum coke, pitch coke, anthracite, amorphous carbon such as pitch, and the like. One or more of these are used.

In the case of a castable composition containing a carbon component such as graphite or amorphous carbon, aluminum, an aluminum-silicon alloy, an aluminum-magnesium alloy, silicon, magnesium or the like is used for the purpose of preventing carbon oxidation and improving strength. Metal powder, carbides such as silicon carbide and boron carbide, borides such as zirconium boride, and glass components such as borosilicate glass can also be used. However, when using a substance that reacts with alkali silicate such as magnesia or a metal, it is desirable to treat the surface of the substance with a silane coupling agent or the like.

The fine powder referred to in the present invention has a particle size of 0.2.
mm or less, and substantially 50% by weight or more of the
The above-mentioned raw material having a size of 4 μm or less is meant.

As the alkali silicate, an aqueous solution of SiO ₂ / R ₂ O molar ratio = 0.5 to 4.0 (R is an alkali metal);
Alternatively, a powder is used. Further, an alkali silicate containing boric acid or the like can be used for the purpose of enhancing stability.

As the fluidity aid, calcined alumina, siliceous fine particles, titania, carbon black and the like have a particle size of 10 μm.
One or more of ultrafine powder and ultrafine particles having a particle size of m or less are used. Here, as the siliceous fine particles, what is called evaporated (volatile) silica generated as a by-product during the production of silicon or ferrosilicon, white carbon, anhydrous or hydrous amorphous silicic acid, shirasu, silica sol, etc. it can.

As the clay, one or more of kaolin family clay represented by ball clay, montmorillonite family clay represented by bentonite, and illite family clay are used.

Clay also acts as a plasticizer that imparts plasticity to the first component. For the purpose of imparting plasticity, an organic plasticizer generally used in a refractory amorphous composition is used. You can also.

The first component of the present invention comprises a deflocculant added for the purpose of obtaining a desired consistency at a low moisture content, a steel fiber added for the purpose of reducing spalling peeling, Organic fibers and metallic aluminum added for the purpose of preventing explosion can be used in the usual customary amounts in common refractory amorphous compositions.

The added water is added in as small an amount as possible to obtain a first component having a pumpable consistency suitable for use with the swing valve pump and the spray nozzle used therewith. To be done.

The flocculant of the second component acts to "overwhelm" or quench the effect of the deflocculant introduced into the first component and immediately convert the first component into a viscous plastic; Ultimately, the castable composition imparts sufficient tackiness and rigidity to adhere to the wall without slumping. That is, the coagulant causes the first component to coagulate and promotes the curing of the alkali silicate.

Examples of the coagulant having such an action include phosphates such as aluminum phosphate, silicates such as sodium silicate, aluminates such as sodium aluminate, carbonates such as sodium carbonate, and water. Hydroxides such as calcium oxide, calcium aluminate, aqueous solutions such as Portland cement,
There are suspensions, powders, and organic solvents such as alcohols, and one or more of these are used.

100% by weight of the solid content of the first component is 0.5 to 5% by weight of the solid content of the alkali silicate (preferably,
(SiO ₂ / R ₂ O molar ratio = 0.5 to 4.0, R is an alkali metal), 3 to 20% by weight of a flow aid, and the balance being refractory aggregate and fine powder. Also, in order to enhance the non-slump property at the time of construction, 5% by weight or less of clay is added to 100% by weight of the solid content of the first component.

The amount of the alkali silicate used is 0.5 to 5% by weight as solid content. The reason for limiting the amount to 0.5% by weight or more is that if the added amount is less than 0.5% by weight, the bonding portion is not sufficiently formed, so that the adhesion is poor and the strength is low. The reason for limiting the content to 5% by weight or less is that if the content exceeds 5% by weight, the consistency of the first component is increased, so that pumping cannot be performed with low moisture.

The amount of the flow aid used is 3 to 20% by weight. The reason that the amount is limited to 3% by weight or more is that the effect of improving the fluidity is insufficient when the amount used is less than 3% by weight.
This is because pumping with low moisture becomes difficult. Also,
The reason why the content is limited to 20% by weight or less is that if the content exceeds 20% by weight, over-sintering occurs at a high temperature due to ultrafine particles and mechanical properties at a high temperature such as corrosion resistance and hot strength deteriorate. This is because there are cases where In particular, it is desirable that the amount of the siliceous fine particles used as the flow aid is 10% by weight or less.

The amount of water to be added depends on the specific gravity and the particle size of the first component, but usually, the first component which can be easily pumped with a water content of 5.0 to 8.0% by weight is obtained.
However, when the first component is pumped to a very long distance and to a high place, the water content may be increased by about 1 to 3% by weight, and the porosity of the material may be intentionally increased like a heat insulating material. Is increased, the amount of water to be added may be further increased.

When it is necessary to increase the construction thickness, 5% by weight or less of clay is added to 100% by weight of the solid content of the first component in order to increase the non-slump property during construction. The reason for limiting the amount of clay used to a maximum of 5% by weight is that as the amount used increases, the effect of water-soluble components in the clay increases, and the pot life (the first component after kneading with water can be pumped. This is because the time for maintaining high consistency is shortened.

The amount of the second component, a flocculant, added immediately before spraying is important because it can adversely affect the desired porosity (apparent porosity) of the castable composition. Porosity is considered to be the most important physical property in castable compositions because all other properties, such as strength and corrosion resistance, are directly proportional to the porosity of any castable composition. Generally, when the porosity increases, both the corrosion resistance and the strength decrease, so that it is desirable that the porosity be as small as possible.
Therefore, the amount of the coagulant added is such that the castable composition cures at a sufficient speed, and the porosity after dehydration as a high-density castable composition is 25% or less, preferably 20% or less.
%. Usually, the above condition is satisfied with an addition amount in the range of 0.2 to 3% by weight based on 100% by weight of the solid content of the first component. 0.2 added
If the amount is less than the percentage by weight, it is difficult to uniformly mix the first component with the nozzle component. If the content is more than 3% by weight, the curing rate of the castable composition becomes too high, so that the porosity of the construction body becomes large. If the coagulant is an aqueous solution or a suspension, the water content of the entire castable composition is increased. This is not preferable because the porosity of the construction body may increase due to the increase in the porosity.

However, when the porosity of the material is intentionally increased as in the case of a heat insulating material, the amount of the coagulant as the second component can be increased. That is, in the case of a castable composition in which heat insulation is more desirable than corrosion resistance and strength, the porosity may be set to be larger than 25%.

[0027] The swing valve pump used in the present invention is a very efficient means of material transfer, and thus the present invention provides a first component having a much smaller amount of water than conventional ones over a long distance and It can be transported to high places. The swing valve pump is usually connected to the nozzle device via steel pipes and / or hoses. Such a nozzle arrangement has an air line line from which air is supplied to the nozzle for blowing a pumpable first component onto the surface to be lined with the refractory material.

A further aspect of the present invention is that when the first component is about to be sprayed onto the surface of a refractory container or device, the second component coagulant is preferably applied via the air line described above. That is to add to the nozzle.

The device for supplying the second component flocculant to the nozzle should have a capacity to balance the given material output of the swing valve pump and the air pressure in the air line (Usually about 3.52 to 7.03 kg / c
m ² = should be capable of generating sufficient pressure to about 50～100Psi) above.

[0030]

Examples Examples and comparative examples according to the present invention are shown in Tables 1, 2 and 3.

For the application of Examples and Comparative Examples of the first component specified in the present invention, the following refractory raw material aggregates and fine powders, alkali silicates, and flow aids were used. That is, the aggregate and fine powder of the refractory raw material have a purity of 99.5%.
Fused alumina, 98.6% pure fused magnesia, 99.7% pure sintered alumina, 99.3% pure sintered spinel, 95.4% pure sintered magnesia, 93.
7% silicon carbide and a pitch of 60.0% fixed carbon were used. As alkali silicate, No. 2 powdered sodium silicate (SiO
₂ / R ₂ O molar ratio = 2.6). As the fluidity aid, calcined alumina having a purity of 99.6% and an average particle size of 1.5 μm and a calcined alumina having a purity of 96.0% and an average particle size of 0.28 μm were used. Although evaporated silica was used, the same effect can be obtained as long as it is described in the embodiment of the present invention. Further, "SECAR71" manufactured by Lafarge Co., Ltd. was used as the calcium aluminate cement, and sodium polyacrylate and sodium ligninsulfonate were used as the deflocculants. As magnesia, a raw material whose surface was treated with a silane coupling agent was used.
All the average particle diameters of the fine powder are values measured by a laser diffraction method.

Further, as an example of the coagulant as the second component specified in the present invention, a 40% by weight aqueous solution of potassium aluminate was used, but the same as described in the embodiment of the present invention. The effect of is obtained.

The amounts of water and flocculant added in the table are indicated by the outer value (+) with respect to 100% by weight of the solid content of the first component.

In the spraying operation, the first components shown in the table are kneaded with a mixer, and the mixture is mixed with Allentown.
0.05mm inside diameter using AP-10 swing valve pump
A 1-meter (2 inch), 30.48-m (100 ft) heavy-duty hose is pressure-fed and further sprayed at the spray nozzle connected to the tip at 5.62 kg / cm.
² (80 psi), 8.5 m ³ / min (300 cft) of compressed air is added together with the coagulant of the second component and a vertically installed 9.29 m ² (100 ft ² ) area of chamotte brick is sprayed onto the surface. The method was performed. Here, a 35.15 kg / cm ² (500 psi) diaphragm chemical pump was used for transferring the flocculant.

The pumping performance items shown in the table were very good when the pump pressure was 140.6 kg / cm ² (2000 psi) or less under the above conditions. The product was marked with “◎” and the pump cylinder pressure was 140.6 kg / cm ² (200
0 psi) is marked with “○” for those that could be pumped, and “x” for those that could not be pumped.

The usable life items shown in the table are indicated by “◎” when the first component stored in a sealed state at 25 ° C. after kneading with water can be pumped even after 120 hours or more has passed.
, "○" indicates that the pumping was possible even after 10 hours or more, but was less than 120 hours, and the pumping time was less than 10 hours and the pot life was not sufficiently extended. Are marked with “x”.

The items of the adhesion rate shown in the table are "◎" when the ratio of the adhesion weight to the total construction weight was very good at 95% or more under the above-mentioned conditions.
A mark, “○” indicates that the sample was good at 90% or more and less than 95%, and “X” indicates a sample that was poor, at less than 90%.

The items of the apparent porosity shown in the table are as follows.
When the apparent porosity measured after baking for 3 hours was 20% or less, a mark “◎” was given. When the apparent porosity was greater than 20% and 25% or less, a mark “○” was given. Is marked with “x”.

The items of the residual linear expansion / contraction rate shown in the table are as follows:
Using a test piece cut out from the construction body constructed under the above-mentioned conditions, a test piece having a residual linear expansion / shrinkage rate of 0% or more before and after firing at 1500 ° C. for 3 hours and showing no oversintering was indicated by “◎”.
Mark, “○” indicates that the oversintering was sufficiently small at less than 0% and −0.5% or more, and “×” indicates that the undersintering was less than -0.5% and was considered unsuitable as a refractory material. Has filled in the seal.

Examples 1 to 3 shown in Tables 1, 2 and 3
20 is the result of the construction body that satisfies the conditions defined by the present invention, the pot life (the time during which the first component after kneading with water maintains the pumpable consistency) is very long, and A good construction body could be obtained.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

Comparative Examples 1 to 7 in Table 2 are described below.

Comparative Example 1 shows a conventional composition using 7% by weight of calcium aluminate cement. Since the calcium aluminate cement showing self-hardening property was used, the pot life was shorter than that of the example of the present invention.

In Comparative Example 2, the amount of the alkali silicate used was changed in the range specified in the present invention (0.5 to 5% by weight).
2, 3, 4 and 5) or less (0.3% by weight), the adhesion rate was not satisfactory.

In Comparative Example 3, the amount of alkali silicate used was changed in the range specified in the present invention (0.5 to 5% by weight).
It could not be pumped because of more than 2, 3, 4 and 5) (7% by weight).

In Comparative Example 4, the amount of the flow aid used was changed within the range specified in the present invention (3 to 20% by weight).
7 and 8) Pumping could not be performed due to the following (1% by weight).

In Comparative Example 5, the amount of the flow aid used was changed within the range specified in the present invention (3 to 20% by weight).
7 and 8) (25% by weight), the oversintering was large and unsuitable as a refractory material.

In Comparative Example 6, since the amount of clay (ball clay) used was larger than the specified range of the present invention (Examples 2, 9, 10 and 11 changed within 5% by weight) (7% by weight),
The pot life was short.

In Comparative Example 7, the apparent porosity after dehydration was large because the amount of the coagulant as the second component was too large.

What is important is that the castable composition of the present invention does not need to be provided with a mold for holding the castable composition in a predetermined position until the composition hardens sufficiently to produce no slump, and can be applied. Of course, this saves the labor and time of installing and removing such forms.

[0053]

Industrial Applicability The present invention provides a non-slump, high-density, extremely low-hardening binder for use in molten metal containers, molten metal processing equipment, cement kilns, incinerators and the like.
Provided is a castable composition having a low moisture content, and a construction method capable of constructing the castable composition without providing a mold or a formwork.

This makes it possible to carry out the kneading process with water collectively at a location remote from the construction site, and to carry out intermittent construction work or construction work requiring a long time.

In addition, there is no need for labor and time to install and remove such forms, thus saving costs.

Claims (4)

[Claims] 1. An alkali silicate of 0.5 to 5% by weight,
A first mixture obtained by kneading 20% by weight of a flow aid and 100% by weight of a solid content composed of refractory aggregate and fine powder with water with water.
A pumpable first component, wherein the water is present in an amount sufficient to achieve a pumpable consistency of the kneaded first component, and added to the first component during construction. A non-slump alkali silicate bond castable composition comprising a second component coagulant. 2. The composition according to claim 1, wherein the composition contains not more than 5% by weight of clay in 100% by weight of the solid content of the first component. 3. A method for spraying a castable composition using a swing valve pump and an auxiliary spray nozzle without using a mold and a mold, comprising: 0.5 to 5% by weight of an alkali silicate, ２０20% by weight of a flow aid and the remaining 100% by weight of solids composed of refractory aggregate and fine powder can be pumped and sprayed through the swing valve pump and the spray nozzle. A pumpable first component is kneaded with water in an amount sufficient to achieve the above, and a second component coagulant is added to the first component in a spray nozzle immediately before spraying the first component. Spraying method. 4. The method according to claim 3, wherein 5% by weight or less of clay is contained in 100% by weight of the solid content of the first component.