JP4664885B2 - Non-slump type ultra-low cement bond castable composition and its construction method - Google Patents

Description

  The present invention relates to a novel non-slump castable composition used for a molten metal container, a molten metal processing apparatus, a cement kiln, an incinerator, etc., and also applies the above castable composition without using a mold or a formwork. On how to do.

  Portland cement based wet spray compositions and methods of construction are old and well known. For example, a mixture containing sand, gravel and Portland cement is made, which is kneaded with water to form a consistency that can be pumped, and this concrete is then pumped into a nozzle. In this nozzle, a cement hardening accelerator and air are added, and the concrete material is sprayed on the surface of an object to be sprayed, for example, a wall surface. On that surface, the concrete hardens quickly enough not to collapse (slump) from the spray surface. Such hardening is the result of chemical hardening accelerators reacting with Portland cement to initiate the hardening action rapidly, thereby rapidly increasing the viscosity of the concrete to a level high enough to prevent slumping. To rise.

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

  As a castable composition for wet spraying using such a calcium aluminate cement as a binder and a construction method thereof, those disclosed in Patent Document 1 are known. However, the composition disclosed in Patent Document 1 contains 20% by weight of calcium aluminate cement, and the amount of added water is as large as 10 to 20% by weight. The composition has poor mechanical properties at high temperatures.

Therefore, Patent Document 2 discloses a castable composition of non-slump property, low moisture, and low calcium aluminate cement.
JP 54-61005 A US Pat. No. 5,549,745

  The castable composition of non-slump, low moisture, and low calcium aluminate cement shown in Patent Document 2 has sufficient corrosion resistance and mechanical properties as a commonly used refractory material, but is contained in the cement. Since calcia forms a low melt with an acid or neutral refractory material, in order to further improve mechanical properties at high temperatures such as corrosion resistance and hot strength, the amount of added calcia component, that is, cement, should be minimized. It may be desirable to reduce.

  An object of the present invention is to provide a non-slump, high-density, low-moisture castable composition in which the amount of cement as a binder is extremely reduced in order to further improve mechanical properties at high temperatures such as corrosion resistance and hot strength. And providing a construction method thereof.

The above-mentioned problem of the present invention is a method for spraying a castable composition using a pump and an incidental spray nozzle without using a mold and a mold, and includes (a) (i) a calcium aluminate cement The calcium aluminate cement in an amount of 0.2 to 1% by weight in a solid content of 100% by weight, and (ii) a total amount of clay and siliceous fine particles of 6 to 15% by weight, (iii) 0.01 to 0.5% by weight of a peptizer; (iv) fused or sintered alumina having a particle size of 75 μm or less, fused or sintered magnesia having a particle size of 75 μm or less, and a particle size of 10 μm or less. Solid content containing 13.8% by weight or more of one or more selected from the group consisting of calcined alumina and silicon carbide having a particle size of 200 μm or less, and (v) a refractory aggregate 100% by weight of water with an amount of 5-11% by weight of the outer shell, A kneaded first pumpable component, (b) pumping the first component to a spray nozzle, (c) a second flocculant in the spray nozzle, spraying construction method and a step of adding the component, and is resolved by the first forming divided Ranaru very low cement bonded castable composition.

  The present invention is a non-slump, high-density, low-moisture castable in which the amount of calcium aluminate cement used as a binder is minimized to be used in molten metal containers, molten metal processing equipment, cement kilns, incinerators, etc. A composition and its construction method are provided.

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

  Furthermore, the castable composition can be applied without providing a mold or a form for holding it in place until it sufficiently cures and no slump is generated, and such a mold is required over labor and time. The cost of installing and removing the frame is saved.

  The first component of the castable composition of the present invention achieves a fire-resistant aggregate and fine powder, calcium aluminate cement, one or both of clay and siliceous fine particles, a peptizer, and a pumpable consistency. Kneaded with a sufficient amount of water.

  The refractory aggregate and fine powder may be any suitable refractory material for molten metal containers, molten metal processing equipment, cement kilns, incinerators, etc., for example, electrofused or sintered alumina, temporary Baked Alumina, Bauxite, Electrofused or Synthetic Mullite, Sillimanite, Andalusite, Kyanite, Van Earth Shale, Chamotte, Rhoishi, Silica, Fused Silica, Fused or Sintered Magnesia, Fused or Sintered Spinel, Electrofused Or sintered zirconia, zircon, chromium ore, fused or sintered magnesia-lime, fused zirconia-mullite, fused alumina-zirconia, titania, silicon carbide, silicon nitride, natural or artificial graphite, petroleum coke, pitch coke , Amorphous carbon such as anthracite, pitch, carbon black and the like, 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, for the purpose of preventing oxidation of carbon and improving the strength, metal powder such as aluminum, aluminum-silicon alloy, aluminum-magnesium alloy, silicon, magnesium, Glass components such as carbides such as silicon carbide and boron carbide, borides such as zirconium boride, and borosilicate glass can also be used.

  In addition, the fine powder said by this invention means the said raw material whose particle size is 0.2 mm or less, and 50 weight% or more of them is 74 micrometers or less substantially.

  Any calcium aluminate cement commonly used in refractory amorphous compositions can be used for the present invention. For example, a calcia content corresponding to JIS Class 1 15 to 22% by weight, a calcia content corresponding to JIS Class 2 25 to 30% by weight, JIS Class 3 or Class 4 A corresponding calcia content of 30 to 40% by weight and other calcium aluminate cements are used.

  As the clay, one or more of kaolin group clay typified by ball clay, montmorillonite group clay typified by bentonite, illite group clay and the like are used. The clay also functions as a plasticizer for imparting plasticity to the first component. Of course, for the purpose of imparting plasticity, an organic plasticizer generally used in a fireproof amorphous composition is used. It can also be used.

  The siliceous fine particles include one or two or more kinds of what is called evaporation (volatile) silica 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. The siliceous fine particles serve as a fluidity aid for imparting fluidity to the first component. Of course, among the above-mentioned refractory fine powders, calcined alumina having a particle size of 10 μm or less, titania, carbon black, etc. The fine powder also has a function as a fluidity aid.

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

  In addition, the first component of the present invention is a steel fiber added for the purpose of reducing peeling due to spalling in a general fire-resistant amorphous composition, organic fiber or metallic aluminum added for the purpose of preventing explosion during drying Can be used in the usual conventional dosage.

  The additive water is added in as small an amount as possible to obtain the first component with a pumpable consistency suitable for use in swing valve pumps and spray nozzles used therewith. To.

  The kneaded first component needs to maintain a pumpable consistency until the second component flocculant is added at the spray nozzle, but this pumpable consistency is required. The pot life, which is a sustained time, can be extended by adding a compound having a chelating action of aluminum ions and calcium ions.

  The second component flocculant “overwhelms” the effect of the peptizer introduced into the first component, ie, disappears, and acts to immediately convert the first component into a viscous plastic, eventually Provides sufficient tack and rigidity to allow the castable material to adhere to the wall without causing slumps. That is, the flocculant aggregates the first component and promotes hydraulic strength due to hydration of the calcium aluminate cement.

  Examples of the flocculant 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 calcium hydroxide. There are aqueous solutions, suspensions or powders of hydroxide, calcium aluminate, Portland cement, etc., and one or more of these are used.

  100 wt% of the solid content of the first component is a calcium aluminate cement in such an amount that the amount of the calcia component containing the calcium aluminate cement is 0.2 to 1 wt% with respect to the solid content of the first component, One or both of clay and siliceous fine particles in a total amount of 6 to 15% by weight, 0.01 to 0.5% by weight of a peptizer, and the remaining refractory aggregate and fine powder Composed.

  The amount of 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 with respect to 100% by weight of the solid content of the first component. The amount of calcium aluminate cement used is limited so that the amount of the calcia component contained in the calcium aluminate cement is 0.2% by weight or more in a solid content of 100% by weight. This is because the bonding portion is not sufficiently formed, resulting in poor adhesion and low strength. Moreover, when the amount of the calcia component contained in the calcium aluminate cement is limited to 1% by weight or less in the solid content of 100% by weight, the amount of the calcia component in the calcium aluminate cement is further increased. This is because the amount of low melt produced at high temperatures increases and the effect of improving mechanical properties at high temperatures such as corrosion resistance and hot strength decreases.

The total amount of clay and siliceous fine particles used is 6 to 15% by weight, and either clay or siliceous fine particles may be used. The reason for limiting the total amount of clay and siliceous fine particles to be 6 % by weight or more is that if the amount is less than 6% by weight, the adhesion is poor and the strength is low. In addition, the total amount of clay and siliceous fine particles used is limited to 15% by weight or less. If the amount exceeds 15% by weight, oversintering phenomenon occurs at high temperatures due to ultrafine particles, and corrosion resistance and This is because the effect of improving the mechanical properties at high temperatures such as hot strength may be reduced. In particular, the amount of siliceous fine particles used is desirably 10% by weight or less.

  The amount of peptizer used is 0.01 to 0.5% by weight. The amount of the peptizer used is limited to 0.01% by weight or more because the effect as a peptizer does not appear when the amount used is less than 0.01% by weight. It is because it cannot be obtained. In addition, the limitation of 0.5% by weight or less is that when the addition amount exceeds 0.5% by weight, the aggregation effect of the flocculant as the second component is reduced and the adhesion of the castable composition is reduced. This is because the peptization property of the first component is reduced, and pumping cannot be performed with low moisture, mechanical properties such as strength may be reduced, and corrosion resistance may be reduced.

  The amount of water to be added naturally varies depending on the specific gravity and particle size constitution of the first component, but usually a first component that 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 intentionally like a heat insulating material. When increasing the value, it is possible to further increase the amount of water added.

  The amount of the flocculant, which is the second component added immediately before spraying, is important because it may adversely affect the desired porosity (apparent porosity) of the castable composition. Porosity is considered the most important physical property in a castable composition because all other properties such as strength and corrosion resistance are directly proportional to the porosity of any castable composition. In general, when the porosity increases, both corrosion resistance and strength decrease, so it is desirable that the porosity be as small as possible. Therefore, the addition amount of the flocculant is adjusted so that the castable composition is cured at a sufficient speed and the porosity after dehydration as a high-density castable composition is 25% or less, preferably 20% or less. To do. 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. When the addition amount is less than 0.2% by weight, it is difficult to uniformly mix with the first component at the nozzle portion. On the other hand, if the amount is more than 3% by weight, the rate of curing of the castable composition becomes too high, so that the porosity of the construction body becomes large. Therefore, the porosity of the construction body may increase, which is not preferable.

  However, when the porosity of the material is intentionally increased as in a heat insulating material, the amount of the flocculant that is the second component can be increased. That is, in the case of a castable composition where heat insulation is desired rather than corrosion resistance and strength, the porosity may be larger than 25%.

  The swing valve pump is a very efficient means of material transfer, and therefore, it is possible to transfer the first component having a very small amount of water compared to the conventional case to a long distance and to a high place. This swing valve pump is usually connected to the nozzle device via a steel pipe and / or hose. Such a nozzle device has an air line pipe, from which air is supplied to the nozzle in order to spray a pumpable first component onto the surface to be lined with a refractory material.

  A further aspect of the invention is that when the first component is about to be sprayed toward the surface of the refractory container or device, the second component flocculant is added to the nozzle, preferably via the air line described above. It is to be.

The device for supplying the second component flocculant to the nozzle should have a capacity that is commensurate with a given material discharge of the swing valve pump, and the air pressure in the air line (usually Sufficient pressures of about 3.52 to 7.03 kg / cm < ² > = about 50 to 100 psi) or more should be possible.

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

  For the application of Examples and Comparative Examples of the first component defined in the present invention, the following refractory raw material aggregate and fine powder, calcium aluminate cement, clay, siliceous fine particles, and peptizer were used. That is, as the aggregate and fine powder of the refractory raw material, 99.5% purity fused alumina, 98.6% purity fused magnesia, 99.7% purity sintered alumina, 99.3% purity sintered Spinel, sintered magnesia having a purity of 95.4%, calcined alumina having a purity of 99.6% and an average particle diameter of 1.5 μm, silicon carbide having a purity of 93.7%, and a pitch having a fixed carbon content of 60.0% were used. “SECAR71” manufactured by Lafarge was used as the calcium aluminate cement, ball clay was used as the clay, and evaporated silica having a purity of 96.0% and an average particle size of 0.28 μm was used as the siliceous fine particles. As the peptizer, polyacrylic acid soda and lignin sulfonic acid soda were used. In addition, what was shown here is not limited to an Example, The equivalent effect will be acquired if it is a thing as described in embodiment of this invention. Here, all the average particle diameters of the fine powder are values measured by a laser diffraction method.

  In addition, as an example of the flocculant serving as the second component defined in the present invention, a 40 wt% potassium aluminate aqueous solution was used. However, the same effect can be obtained as long as it is described in the embodiment of the present invention. can get.

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

The spraying is performed by kneading the first component listed in the table with a mixer and using an Allentown AP-10 swing valve pump with an inner diameter of 0.051 m (2 inches) and a length of 30.48 m (100 ft). ) In a heavy duty hose, and at the spray nozzle connected to the tip, compressed air of 5.52 kg / cm ² (80 psi) and 8.5 m ³ / min (300 cft) is a second component flocculant. A chamotte brick with an area of 9.29 m ² (100 ft ² ) installed vertically and sprayed on the surface was carried out. Here, a 35.15 kg / cm ² (500 psi) diaphragm chemical pump was used for transferring the flocculant.

The pump pumpability shown in the table is that the pump pumpability is very good when the cylinder pressure of the pump is 140.6 kg / cm ² (2000 psi) or less when the construction is performed under the above conditions. “◎” mark, if the pump cylinder pressure exceeded 140.6 kg / cm ² (2000 psi) but pump pumping was possible, “○” mark, and if pump pumping was not possible, “×” ”Is filled in.

  The items of the adhesion rate shown in the table are “◎” mark and 90% or more when the ratio of the adhesion weight with respect to the total construction weight is 95% or more when the construction is performed under the above conditions. The mark “◯” is marked for those that are good, less than 95%, and the mark “X” is marked for those that are poor, less than 90%.

  The item of apparent porosity shown in the table is “◎” when the apparent porosity measured after firing the test piece cut out from the construction body constructed under the above conditions at 500 ° C. for 3 hours is 20% or less. A mark “○” is entered for a mark larger than 20% and 25% or less, and a mark “X” is marked for a mark larger than 25%.

  The items of residual linear expansion / shrinkage rate shown in the table are as follows. The test piece cut out from the construction body constructed under the above conditions was used, and the residual linear expansion / shrinkage rate was 0% or more before and after firing at 1500 ° C. for 3 hours. For those that did not show oversintering, “◎” mark, smaller than 0%, −0.5% or more, and for those where oversintering was sufficiently small, “○” mark, smaller than −0.5%, fire resistance Items marked as inappropriate are marked with an “x”.

  The item of hot bending strength shown in the table is a three-point bending strength of 100 mm span in an electric furnace at 1500 ° C. using a test piece having a cross section of 40 mm and a length of 160 mm cut out from the construction body constructed under the above conditions. When the hot bending strength is 200% or more of the hot bending strength of Comparative Example 1 (an example in which the amount of calcium aluminate cement used is large), which is very high, is marked with “◎”, 150 % Is less than 200% and the hot strength is large, and “X” is marked if the hot strength is insufficient and less than 150%.

Moreover, the item of corrosion resistance shown in the table is that a test piece is cut out from a construction body constructed under the above conditions, and a slag rotation sampling test is performed at 1600 ° C. using slag of CaO / SiO ₂ (molar ratio) = 1.2. When the corrosion rate is 60% or less of the erosion rate of Comparative Example 1 and the corrosion resistance is very good, “◎” mark, and when it is larger than 60% and 90% or less, the corrosion resistance is “○” mark. In addition, “x” marks are entered for those that are larger than 90% and whose corrosion resistance is insufficiently improved.

Examples 1 to 20 shown in Table 1, Table 2, and Table 4 are the results of constructions satisfying the conditions defined by the present invention, and the amount of calcium aluminate cement used as a binder was reduced to the limit. A good construction body could be obtained.

Table 3 shows Comparative Examples 1 to 10.

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

  In Comparative Example 2, the amount of calcium aluminate cement used is within the specified range of the present invention (the amount of the calcia component contained in the calcium aluminate cement is 0.2 to 1% with respect to 100% by weight of the total solid content of the first component). Examples 1, 2, 3 and 4) changed in% (the amount of calcia contained in the calcium aluminate cement is 0.1% by weight relative to 100% by weight of the total solid content of the first component) For this reason, the adhesion rate was not satisfactory.

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

  In Reference Examples 1, 2, and 3, and Examples 5, 6, 7, 8, 9, 10, and 11, the total of clay and siliceous fine particles was changed at 1 to 15% by weight. In Comparative Examples 4 and 5, since the amount of clay and siliceous fine particles used was 1 to 15% by weight (0.5% by weight), the adhesion rate was not satisfactory.

  In Reference Examples 1, 2, and 3, and Examples 5, 6, 7, 8, 9, 10, and 11, the total of clay and siliceous fine particles was changed at 1 to 15% by weight. In Comparative Examples 6 and 7, the amount of clay and siliceous fine particles used is more than 1 to 15% by weight (18.0% by weight), so oversintering is large and inappropriate as a refractory material, and hot strength The improvement was small.

  In Comparative Example 8, the amount of the peptizer used was not more than the specified range of the present invention (Examples 2, 12 and 13 varied from 0.01 to 0.5% by weight) (0.005% by weight). It was not possible to pump with low moisture.

  In Comparative Example 9, the amount of the peptizer used was larger (0.7% by weight) than the specified range of the present invention (Examples 2, 12, and 13 varied from 0.01 to 0.5% by weight). Adhesion was poor.

  In Comparative Example 10, the apparent porosity after dehydration was large because the addition amount of the flocculant as the second component was too large.

  Importantly, the castable composition of the present invention can be applied without the need to provide a formwork to hold it in place before it fully cures and no longer produces slump. The cost of providing and removing such a mold over force and time is saved.

Claims (2)

A method of spraying a castable composition using a pump and an incidental spray nozzle without using a mold and a mold,
(A) (i) calcium aluminate cement in an amount such that the amount of the calcia component contained in the calcium aluminate cement is 0.2 to 1% by weight in a solid content of 100% by weight; and (ii) clay and silicic acid 6 to 15% by weight of fine particles, (iii) 0.01 to 0.5% by weight of a peptizer, (iv) electrofused or sintered alumina having a particle size of 75 μm or less, and a particle size of 75 μm or less One or two or more selected from the group consisting of electrofused or sintered magnesia, calcined alumina having a particle size of 10 μm or less, and silicon carbide having a particle size of 200 μm or less, and a total amount of 13.8% by weight or more ( v) producing a pumpable first component obtained by kneading a solid content of 100% by weight containing a refractory aggregate with water in an amount of 5 to 11% by weight with respect to the solid content;
(B) pumping the first component to a spray nozzle;
(C) A spray construction method including a step of adding the second component flocculant to the first component in the spray nozzle. It is used to spray construction method according to claim 1, wherein the first formed divided Ranaru very low cement bonded castable composition.