JPH10182248A - Non-slumping very low cement based bond castable composition and working method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-slumping, high density and low water content castable composition minimized in the quantity of use of a calcium aluminate cement as a binder to improve corrosion resistance and mechanical strength at a high temp. such as hot strength and its working method. SOLUTION: The non-slumping very low cement based castable composition is composed of a 1st pump transportable component, which is prepared by kneading 100wt.% solid matter consisting of the calcium aluminate cement in a quantity to be 0.2-1wt.% per 100wt.% solid portion in quantity of the calcia component contained in the calcium aluminate cement, 1-15wt.% in total of a clay and a siliceous fine powder, 0.01-0.5wt.% deflocculant and the balance refractory aggregate and fine powder with water in a quantity enough to attain the consistency capable of pump transportation, and a 2nd component of a flocculant, which is added into the 1st component at the time of working.

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.

Therefore, U.S. Pat. S. Patent 55497
At 45, a castable composition of a non-slump, low moisture, low calcium aluminate cement is shown.

[0006]

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 it has sufficient corrosion resistance and mechanical properties as a commonly used refractory material, calcia contained in cement forms a low melt with acidic or neutral refractory material,
Furthermore, in order to improve mechanical properties at high temperatures such as corrosion resistance and hot strength, it may be desirable to reduce the addition amount of the calcia component, that is, the cement, to the limit.

[0007] An object of the present invention is to provide a non-slump, high-density, low-moisture material with a very small amount of cement as a binder in order to further improve mechanical properties at high temperatures such as corrosion resistance and hot strength. An object of the present invention is to provide a castable composition and a method for applying the same.

[0008]

According to the present invention, there is provided a calcium aluminate cement in which an amount of a calcia component contained in the calcium aluminate cement is 0.2 to 1% by weight based on 100% by weight of solids, A total of 1 to 15% by weight of clay and siliceous fine particles, 0.01 to 0.5% by weight of a deflocculant, and a balance of solids 100 consisting of refractory aggregate and fine powder
% By weight of a pumpable first component kneaded with water in an amount sufficient to achieve a pumpable consistency, and a second component coagulant added to the first component during construction. The present invention is achieved by an extremely low cement bond castable composition and a method for applying the same.

[0009]

DETAILED DESCRIPTION OF THE INVENTION First of the castable composition of the present invention.
The ingredients consist of refractory aggregates and fines, calcium aluminate cement, one or both of clay and siliceous particulates, a deflocculant, and a sufficient amount of water to achieve a pumpable consistency. Kneaded.

The refractory aggregate and fine powder may be any suitable refractory materials for molten metal containers, molten metal processing equipment, cement kilns, incinerators 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,
Titania, silicon carbide, silicon nitride, natural or artificial graphite,
Examples thereof include petroleum coke, pitch coke, anthracite, pitch, and amorphous carbon such as carbon black, and 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.

In the present invention, fine powder 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 calcium aluminate cement,
Any of the commonly used refractory amorphous compositions can be used for the present invention. For example, a calcia content of 15 to 22% by weight corresponding to the first type of JIS, and a calcia content of 25 to 3 corresponding to the second type of JIS
0% by weight, 30 to 40% by weight of calcia content corresponding to the third or fourth type of JIS, and
One or more of other calcium aluminate cements are used.

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. Of course, for the purpose of imparting plasticity, an organic plasticizer generally used in a refractory amorphous composition is used. Can also be used.

Examples of the siliceous fine particles include those called evaporated (volatile) silica which is generated as a by-product during the production of silicon or ferrosilicon, white carbon, anhydrous or hydrous amorphous silicic acid, shirasu, and silica sol.
Use two or more species. The siliceous fine particles also function as a flow aid to impart flow to the first component, but of course,
Among the refractory fine powders described above, fine powders such as calcined alumina, titania, and carbon black having a particle size of 10 μm or less also have a function as a flow aid.

As the deflocculant, one or more of condensed phosphoric acid, polyacrylic acid, polycarboxylic acid, phosphonic acid, humic acid, alkylsulfonic acid, aromatic sulfonic acid and the like, or salts thereof are used. .

The first component of the present invention is a steel fiber added for the purpose of reducing spalling peeling in a general refractory amorphous composition, and an organic fiber added for the purpose of preventing explosion during drying. And metallic aluminum can be used in the usual customary amounts.

The addition 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 kneaded first component needs to maintain a pumpable consistency until the coagulant of the second component is added at the spray nozzle portion. The pot life, which is the time for maintaining the tension, can be extended by adding a compound capable of chelating aluminum ions and calcium ions.

The coagulant of the second component acts to "overwhelm" the effect of the deflocculant introduced into the first component, ie, to extinguish it and immediately convert the first component into a viscous plastic, Eventually, the castable material will have sufficient tackiness and rigidity to adhere to the wall without slumping. That is, the coagulant causes the first component to coagulate and promotes hydraulic setting by hydration of the calcium aluminate cement.

Examples of the coagulant having such an action include aluminates such as sodium aluminate, carbonates such as sodium carbonate, alkali silicates such as sodium silicate, chlorides such as calcium chloride, sodium hydroxide and hydroxide. There are aqueous solutions, suspensions and powders of hydroxides such as calcium, calcium aluminate, Portland cement and the like, and one or more of these are used.

The solid content of 100% by weight of the first component is such that the amount of the calcia component contained in the calcium aluminate cement is 0.2 to 1% by weight based on the solid content of the first component. A cement, an amount of clay and / or siliceous fine particles in an amount of 1 to 15% by weight in total, 0.01 to 0.5% by weight of a deflocculant, the balance of refractory aggregate and It is composed of fine powder.

The amount of the calcium aluminate cement used is such that the amount of the calcia component contained in the calcium aluminate cement is 0.2 to 1% by weight based on 100% by weight of the solid content of the first component. The amount of calcium aluminate cement used is determined by the amount of the calcia component contained in the calcium aluminate cement being 100% by weight solids.
The reason why the content is limited to 0.2% by weight or more is that if the amount used is less than that, the bonding portion is not sufficiently formed, so that the adhesion is poor and the strength is low. In addition, solid content 10
The reason why the amount of the calcia component contained in the calcium aluminate cement is limited to 1% by weight or less in 0% by weight is that when the amount of the calcia component in the calcium aluminate cement is further increased, the low temperature at a high temperature becomes low. This is because the amount of generated melt increases, and the effect of improving mechanical properties at high temperatures such as corrosion resistance and hot strength decreases.

The total amount of the clay and the siliceous fine particles used is 1 to 15% by weight, and either one of the clay and the siliceous fine particles may be used. The reason why the total usage of the clay and the siliceous fine particles is limited to 1% by weight or more is that if the usage is less than 1% by weight, the adhesion is poor and the strength becomes low. In addition, the reason why the total use amount of the clay and the siliceous fine particles is limited to 15% by weight or less is that if it exceeds 15% by weight, the particles are excessively fine particles, resulting in oversintering at high temperatures, corrosion resistance and corrosion resistance. This is because the effect of improving mechanical properties at high temperatures such as hot strength may be reduced. In particular, it is desirable that the use amount of the siliceous fine particles be 10% by weight or less.

The amount of the peptizer used is 0.01 to 0.5% by weight. The use amount of the deflocculant is limited to 0.01% by weight or more because the effect as a deflocculant is not exhibited when the use amount is less than 0.01% by weight. Is not obtained. 0.5% by weight
When the amount added exceeds 0.5% by weight, the coagulant effect of the coagulant, which is the second component, is reduced, so that the adhesion of the castable composition is reduced and the peptizing property of the first component is reduced. The pump pressure can not be pumped with low moisture,
This is because mechanical properties such as strength may be reduced, or corrosion resistance may be reduced.

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.

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%.

The swing valve pump used in the present invention is a very efficient means of material transfer, and therefore the present invention provides a first component having a much lower moisture content than in the prior art.
It can be transported over long distances and 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 coagulant of the second component is applied, preferably 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.

[0032]

Examples Examples and comparative examples according to the present invention are shown in Tables 1, 2, 3 and 4.

The application of the examples and comparative examples of the first component specified in the present invention are as follows: Aggregate and fine powder of refractory raw materials, calcium aluminate cement, clay, siliceous fine particles, and peptizer are used. used. That is, as the refractory raw material aggregate and fine powder, 99.5% pure fused alumina, 9 pure purity
8.6% electrofused magnesia, 99.7% purity sintered alumina, 99.3% purity spinel, 95.4% purity
Magnesia, purity 99.6%, average particle size 1.5μm
Calcined alumina, silicon carbide having a purity of 93.7%, and a pitch having a fixed carbon amount of 60.0% were used. As a calcium aluminate cement, "SECAR7" manufactured by Lafarge
1 ", ball clay is used as clay, and purity is 96.0% and average particle diameter is 0.28 μm as siliceous fine particles.
m of evaporated silica were used. As the peptizer, sodium polyacrylate and sodium ligninsulfonate were used. It should be noted that what is shown here is not limited to the examples, and equivalent effects can be obtained as long as they are described in the embodiments of the present invention. Here, all the average particle diameters of the fine powder are values measured by a laser diffraction method.

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 an outer value (+) with respect to 100% by weight of the solid content of the first component.

In the spraying operation, the first components listed 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 items of pumping performance 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 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 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:
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.

The items of the hot bending strength shown in the table are the cross section □ 40 mm cut out from the construction body constructed under the above conditions,
Using a 160 mm long test piece in an electric furnace at 1500 ° C,
The three-point bending strength of a span of 100 mm was measured, and the hot bending strength was 200% or more of the hot bending strength of Comparative Example 1 (an example in which a large amount of calcium aluminate cement was used), and the hot bending strength was extremely large. Is "◎" mark, 150% or more 2
If the hot strength is as high as less than 00%, mark "O", 15
If it is less than 0%, the improvement of hot strength is insufficient, and the mark "x" is entered.

In the corrosion resistance items shown in the table, a test piece was cut out from the construction body constructed under the above conditions, and a slag rotation tasting test was performed using a slag of CaO / SiO ₂ (molar ratio) = 1.2. The test was performed at 1600 ° C., and the erosion rate was 60% or less of the erosion rate of Comparative Example 1 and marked with “耐” when the corrosion resistance was very good, and when the erosion rate was greater than 60% and 90% or less, the corrosion resistance was good. Is marked with a “○”, and those with a corrosion resistance greater than 90% and insufficiently improved are marked with a “x”.

Examples 1 to 3 shown in Tables 1, 2 and 4
No. 25 is the result of the construction body satisfying the conditions specified by the present invention, and a good construction body in which the amount of the calcium aluminate cement used as the binder was minimized was obtained.

[Table 1]

[Table 2]

[Table 4]

Table 3 shows Comparative Examples 1 to 10.

[Table 3]

Comparative Example 1 shows a conventional composition using 7% by weight of calcium aluminate cement. Because of the large amount of calcium aluminate cement, the corrosion resistance and hot strength were inferior to those of the examples of the present invention.

In Comparative Example 2, the amount of the calcium aluminate cement used was within the range specified in the present invention (the amount of the calcia component contained in the calcium aluminate cement was 0.2% based on 100% by weight of the total solids of the first component). Examples 1, 2, 3 and 4) in which the amount of the calcia component contained in the calcium aluminate cement was 0.1 wt% based on 100 wt% of the total solid content of the first component. %), The adhesion rate was not satisfactory.

In Comparative Example 3, the amount of the calcium aluminate cement used was within the range specified in the present invention (the amount of the calcia component contained in the calcium aluminate cement was 0.2% based on 100% by weight of the total solids of the first component). (Examples 1, 2, 3 and 4) varied by １1% by weight. The amount of the calcia component contained in the calcium aluminate cement was 1.5 to 100% by weight of the total solid content of the first component. % By weight), the improvement in corrosion resistance and hot strength was small.

In Comparative Examples 4 and 5, the amounts of clay and siliceous fine particles used were within the specified range of the present invention (Examples 5, 6, 7, 8 in which the total amount of clay and siliceous fine particles was changed from 1 to 15% by weight). ,
9, 10, 11, 12, 13 and 14) or less (0.5% by weight), the adhesion rate was not satisfactory.

In Comparative Examples 6 and 7, the amounts of clay and siliceous fine particles used were within the specified range of the present invention (Examples 5, 6, 7, 8 in which the total amount of clay and siliceous fine particles was changed from 1 to 15% by weight). ,
9, 10, 11, 12, 13, and 14)
(8.0% by weight), which resulted in large oversintering, which was unsuitable as a refractory material, and that the improvement in hot strength was small.

In Comparative Example 8, the amount of the deflocculant was changed in the range specified in the present invention (0.01 to 0.5% by weight).
15 and 16) Due to the following (0.005% by weight), pumping could not be performed with low moisture.

In Comparative Example 9, the amount of the deflocculant was changed in the range specified in the present invention (0.01 to 0.5% by weight).
15 and 16) (0.7% by weight), the adhesion was poor.

In Comparative Example 10, 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 can be applied without the need to provide a mold for holding the castable composition in a predetermined position until the composition hardens sufficiently to generate a slump. This saves the labor and time of installing and removing such forms.

[0058]

Industrial Applicability The present invention provides a non-slump, high-density, extremely low-amount calcium aluminate cement as a binder for use in molten metal containers, molten metal processing equipment, cement kilns, incinerators and the like. And a low-moisture castable composition and a method for applying the same.

This makes it possible to improve mechanical properties at high temperatures such as corrosion resistance and hot strength.

Further, the castable composition can be applied without providing a mold or a mold for holding the castable composition in a predetermined position until the castable composition hardens sufficiently to produce no slump. The cost of providing and removing such forms is eliminated.

Claims (2)

[Claims] 1. The amount of a calcia component contained in a calcium aluminate cement is 0.2% in a solid content of 100% by weight.
Calcium aluminate cement in an amount of １1% by weight, and clay and siliceous fine particles in a total amount of 1 to 15% by weight,
A first component obtained by kneading 0.01 to 0.5% by weight of a deflocculant and 100% by weight of a solid content consisting of a refractory aggregate and fine powder with water, the water being kneaded; From the pumpable first component present in an amount sufficient to achieve the pumpable consistency of the first component pumped and the second component coagulant added to the first component during construction. Ultra low cement bond castable composition. 2. A method for spraying and casting a castable composition using a swing valve pump and an attached spraying nozzle without using a mold and a mold, wherein the amount of calcia component contained in the calcium aluminate cement is determined. Has a solid content of 100
0.2 to 1% by weight of calcium aluminate cement, and clay and siliceous fine particles in a total amount of 1 to 1% by weight.
5% by weight, 0.01 to 0.5% by weight of a deflocculant, and 100% by weight of a solid content composed of a refractory aggregate and fine powder
Is kneaded with a sufficient amount of water to achieve a pumpable and sprayable consistency through the swing valve pump and the spray nozzle to form a pumpable first component, and blow the first component. Second in the spray nozzle just before spraying
A spraying construction method in which a coagulant of a component is added to the first component.