JP2010168272A - Heat insulating monolithic refractory and method of constructing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat insulating monolithic refractory which suppresses the propagation and growth of crack occurring in use at from a room temperature to a high temperature of ≥1,000°C without using granular or cotton-like ceramic fiber or using porous insulating aggregate and can be used for a long period of time without being exfoliated. <P>SOLUTION: The heat insulating monolithic refractory is obtained by preparing refractory slurry obtained by kneading a refractory composition comprising 60-90 mass% refractory fine powder having ≤300 μm particle diameter and 10-40 mass% binder, a foaming agent and a kneading liquid having 5-220 mPa s viscosity in an amount of 25-40 pts.mass per 100 pts.mass refractory composition, jetting air into the refractory slurry in an amount of 0.3-1.2 L per 1 L refractory slurry and stirring. A construction body is formed having 70-85% apparent porosity and a pore diameter distribution in which cumulative 80% diameter is ≤500 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a heat-insulating amorphous refractory with less cracking due to dehydration and heating after construction, and its construction method, and in particular, heat insulation equipment for lining materials for industrial furnaces such as heating furnaces and soaking furnaces, pot lids, etc. TECHNICAL FIELD The present invention relates to a heat-insulating amorphous refractory used in facilities that require high fire resistance and high heat insulation, such as a lining material, and a method for constructing such heat-insulating amorphous refractory.

  Conventionally, heat-insulating amorphous refractories have been used in atmosphere furnaces such as heating furnaces for steel materials and soaking furnaces. As such heat-insulating amorphous refractories, for example, JP-A-51-067307 (Patent Document 1) and JP-A-57-071877 (Patent Document 2) add a foaming agent to a refractory castable, A method of providing heat insulation by introducing air while kneading with water has been proposed. However, these heat-insulating castables are made of general fire-resistant aggregates, fire-resistant fine powders, binders, etc., and are made by foaming fire-resistant castables that do not have particularly high heat insulating properties by the action of foaming agents. It does not exhibit sufficiently good heat insulation.

  As a method for producing a construction body excellent in heat insulation using an amorphous refractory, Japanese Patent Application Laid-Open No. 2007-326733 (Patent Document 3) and Japanese Patent Application Laid-Open No. 2008-013430 (Patent Document 4) Foaming agent, foaming agent, pore-forming agent and water are added to the binder, air is taken into the slurry while kneading, and molding is carried out to form bubbles by foaming the foaming agent and burning the pore-forming agent. The manufacturing method of the construction body made is proposed. However, these methods are all related to constructions made by heating the molded body, so-called fixed refractories, and when used in a constrained state like an irregular refractory construction, dehydration and sintering There is a problem that cracks are likely to occur due to shrinkage due to.

  Usually, the construction body of the irregular-shaped refractory material obtained by kneading on site and directly constructing it is heated after construction and used at a high temperature as it is in a restrained state. At this time, the construction body of the irregular refractory material is not only simply expanded by heat of the refractory raw material, but also contracted due to dehydration of water during kneading, and contraction due to sintering of refractory fine powder at a high temperature. By repeating expansion and contraction while being constrained, a crack is generated in the construction body, and peeling or dropping occurs.

  Japanese Patent Laid-Open No. 06-087666 (Patent Document 5) proposes a method of forming a construction body using a fire-resistant and heat-insulating castable containing a fire-resistant aggregate, granular cotton-like ceramic fibers, and a foaming agent. It describes that the propagation of cracks can be suppressed by the use of the shaped ceramic fiber. However, there is a problem that the construction environment is bad because ceramic fibers are scattered in a large amount in the atmosphere.

  Japanese Patent Application Laid-Open No. 2002-179471 (Patent Document 6) proposes a method for obtaining a heat-insulating and fire-resistant construction body using a fire-resistant and heat-insulating castable composed of a porous heat-insulating aggregate and hydraulic alumina. It is described that the propagation of cracks can be suppressed even if cracks occur due to the use of. However, since there are few kinds of porous heat-insulated aggregates having high fire resistance and optimal pore size distribution and porosity, they are expensive, so using such porous heat-insulated aggregates, heat insulation fire resistance Manufacturing a construction will increase costs.

Japanese Patent Laid-Open No. 51-067307 JP 57-071877 JP 2007-326733 A Japanese Patent Laid-Open No. 2008-013430 Japanese Patent Laid-Open No. 06-087666 JP 2002-179471 A

  Therefore, the object of the present invention is to suppress the propagation and growth of cracks that occur during use at high temperatures from room temperature to 1000 ° C or higher, without using granular cotton-like ceramic fibers or porous heat insulating aggregates, and peeling. The object is to provide a heat-insulating amorphous refractory that can be used for a long period of time.

  Another object of the present invention is to provide a construction method capable of constructing the heat insulating amorphous refractory by a simple method according to various situations in the field.

  As a result of earnest research to obtain a construction body having excellent heat insulation and fire resistance without using granular cotton-like ceramic fibers, porous aggregates, etc., the present inventors, Even if it is a refractory composition comprising a fire-resistant fine powder and a binder having high fire resistance, the construction body has excellent fire resistance and heat insulation by controlling the bubble diameter of air taken in a large amount sufficiently small At the same time, the inventors have found that the thermal stress is relaxed and the generation of cracks is suppressed, and the present invention has been conceived.

  That is, the heat-insulating amorphous refractory of the present invention comprises a refractory composition comprising 60 to 90% by mass of a refractory fine powder having a particle size of 300 μm or less and a binder of 10 to 40% by mass, a foaming agent, and a viscosity of 5 to 5%. To a refractory slurry obtained by kneading 220 mPas and an addition amount of 25 to 40 parts by mass with respect to 100 parts by mass of the refractory composition, 0.3 to 1.2 per liter of the refractory slurry A heat-insulating amorphous refractory obtained by injecting and agitating L air, and firing at 1,000 ° C. for 3 hours, with an apparent porosity of 70 to 85% and a cumulative 80% diameter of 500 μm or less. It becomes the construction body which has bubble diameter distribution, It is characterized by the above-mentioned.

  The binder is preferably an alumina cement.

  The construction method of the heat-insulating amorphous refractory of the present invention comprises a refractory composition comprising 60 to 90% by mass of a refractory fine powder having a particle size of 300 μm or less and a binder of 10 to 40% by mass, a foaming agent, and a viscosity of 5 A refractory slurry obtained by kneading ˜220 mPa · s and a kneading liquid having an addition amount of 25 to 40 parts by mass with respect to 100 parts by mass of the refractory composition is continuously stirred in a pressure feeding pipe by a pressure pump. The refractory slurry is injected with 0.3 to 1.2 L of air per 1 L of slurry, and the refractory slurry is stirred with the continuous stirrer to form a heat-insulating amorphous refractory having fine bubbles. The heat-insulating amorphous refractory prepared and discharged from the continuous stirrer is poured into a construction site.

  The continuous stirrer includes a cylindrical stator having a large number of stator pins on the inner peripheral surface, and a rotor rotating in the cylindrical stator and having a large number of rotor pins on the outer peripheral surface. It is preferable that the refractory slurry between the stator pin and the rotor pin is agitated by rotating at a speed of at least / sec, so that the bubbles in the refractory slurry are refined.

  The binder is preferably an alumina cement.

  The heat-insulating amorphous refractory of the present invention is resistant to crack propagation and growth during high-temperature use without using porous raw materials such as granular cotton-like ceramic fibers and porous heat-insulated aggregates. And the construction body excellent in heat insulation can be used stably over a long period of time.

  With the construction method of the heat-insulating amorphous refractory according to the present invention, the heat-insulating amorphous refractory that can be used stably over a long period of time while being excellent in fire resistance and heat insulation can be used in a simple manner according to the situation at the site. Can be constructed.

It is the schematic which shows an example of the equipment which constructs the heat insulation irregular refractory material of this invention. It is the elements on larger scale which show the compressed air injection | pouring part of the construction equipment of FIG. 1, Comprising: (a) shows the assembled state, (b) shows the disassembled state. It is the elements on larger scale which show the compressed air injection | pouring part of the construction equipment of FIG. 1, Comprising: (a) shows the state which is injecting compressed air, (b) shows the state which is not injecting compressed air. 1 shows a continuous stirrer of the construction equipment of FIG. 1, (a) is a partially enlarged sectional view, (b) is a sectional view of AA of (a), and (c) shows a stator and rotor of (a). It is a disassembled perspective view. It is the schematic which shows another example of the installation which constructs the heat insulation irregular refractory material of this invention.

[1] Composition of heat-insulating amorphous refractory The heat-insulating amorphous refractory comprises a fire-resistant composition comprising 60 to 90% by mass of refractory fine powder having a particle size of 300 μm or less and a binder of 10 to 40% by mass, and a foaming agent. In addition, 0.3 to 1.2 L of air per 1 L of the refractory slurry is injected into the refractory slurry obtained by kneading the kneaded liquid and stirred. The viscosity of the kneaded liquid is 5 to 220 mPa · s, and the addition amount is 25 to 40 parts by mass with respect to 100 parts by mass of the refractory composition. The heat-insulating amorphous refractory is fired at 1,000 ° C. for 3 hours to form a construction body having an apparent porosity of 70 to 85% and a cell diameter distribution with a cumulative 80% diameter of 500 μm or less.

(1) Refractory composition
(a) Refractory fine powder If the particle size of the refractory fine powder is more than 300 μm, the particle gap becomes large and the bubble diameter becomes large, and cracking due to dehydration and heating after construction tends to occur. Here, “particle size of 300 μm or less” means that there is no refractory fine powder of more than 300 μm in an amount that substantially affects the generation of bubbles. Specifically, if the content of the refractory fine powder exceeding 300 μm is less than 10% by mass, it can be said that the particle diameter is 300 μm or less. The particle size of the refractory fine powder is preferably 200 μm or less. If the refractory fine powder is less than 60% by mass, the amount of binder will be relatively large, so the fire resistance of the construction will be low. If it exceeds 90% by mass, the amount of binder will be relatively small, so The strength is lowered.

  The fire-resistant fine powder is not limited as long as it can be used at a high temperature of 1,000 ° C. or higher. Fine powder of alumina such as calcined alumina, sintered alumina, and fused alumina, fine powder of spinel such as sintered spinel and fused spinel, Examples thereof include magnesia fine powder such as fused magnesia and seawater magnesia, silica fine powder, titania fine powder, mullite fine powder, zirconia fine powder, silicon carbide fine powder, and carbon fine powder. These refractory fine powders may be used alone or in combination.

(b) Binder A binder is a material that quickly cures a heat-insulating amorphous refractory that has been constructed at room temperature, and is composed of alumina cement, hydraulic transition alumina (eg, ρ-alumina), alkali metal or alkaline earth metal aluminate. Examples thereof include salts, alkali metal or alkaline earth metal phosphates, alkali metal or alkaline earth metal silicates, and basic aluminum lactate. Alumina cement is preferred in terms of heat resistance and curing strength.

(2) Foaming agent The foaming agent is not particularly limited as long as it foams the refractory slurry well, and anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. Synthetic surfactant foaming agents, resin soap foaming agents, hydrolyzed protein foaming agents, and the like. 0.1-3 mass parts is preferable with respect to 100 mass parts of refractory compositions, and, as for the addition amount of a foaming agent, 0.5-2 mass parts is more preferable. If the foaming agent is less than 0.1 part by mass, it is difficult to make bubbles fine. Even if the amount of the foaming agent exceeds 3 parts by mass, a further foaming effect cannot be obtained, which causes a decrease in strength of the construction body.

(3) Kneading liquid Examples of the kneading liquid include water, an aqueous solution or an aqueous dispersion of a water-soluble polymer, and an aqueous solution or an aqueous dispersion of a water-soluble polymer is preferable because of high viscosity. Water-soluble polymers include plant polysaccharides, microbial fermentation polysaccharides, natural polymers such as proteins, semi-synthetic polymers such as cellulose derivatives, starch derivatives, and alginic acid derivatives, water-soluble vinyl resins, and water-soluble acrylic resins. Etc.

  The viscosity of the kneaded liquid is 5 to 220 mPa · s. When the viscosity is less than 5 mPa · s, it is difficult to obtain fine bubbles even when stirred at a high speed, and bubbles are likely to be bonded or lost. On the other hand, if it exceeds 220 mPa · s, the fluidity of the refractory slurry becomes low, so that even if it is stirred at a high speed, it is difficult to shear and it is difficult to obtain fine bubbles. The addition amount of the kneading liquid is 25 to 40 parts by mass with respect to 100 parts by mass of the refractory composition. If the amount added is less than 25 parts by mass, a large amount of air cannot be contained, so that the thermal conductivity increases. If the amount of added water exceeds 40 parts by mass, the bubble diameter increases and the strength of the construction body decreases.

(4) Refractory slurry The refractory slurry is obtained by mixing and kneading the refractory composition, the foaming agent, and the kneading liquid. Mixing and kneading are preferably performed using a pan-type mixer or the like.

[2] Construction method Air is injected into the refractory slurry and agitated by applying high shear to refine the bubbles in the refractory slurry to produce a heat-insulating amorphous refractory. The apparent porosity of the construction body is determined by the amount of air injected into the refractory slurry. In order for the construction body to have a porosity of 70 to 85% when the heat-insulating amorphous refractory is fired at 1,000 ° C. for 3 hours, the amount of injected air is 0.3 to 1.2 with respect to 1 L of refractory slurry. L (under atmospheric pressure) is preferable, and 0.5 to 1.0 L (under atmospheric pressure) is more preferable. When this injection amount is less than 0.3 L, the apparent porosity is less than 70% and the heat insulating property is lowered. When it exceeds 1.2 L, the obtained construction body has an apparent porosity of more than 85% and the strength of the construction body is high. descend.

(1) Introduction of compressed air FIGS. 1 to 4 show an example of a construction apparatus for heat-insulating amorphous refractories. This construction apparatus includes a pump 1 for feeding a refractory slurry A prepared using a pan mixer, a continuous agitator 2, a pipe 3 connecting the pump 1 and the continuous agitator 2, and a continuous agitator. 2, a compressed air introduction device 4 attached to a portion of the nearest pipe 3, a pipe 5 attached to the outlet 24 of the continuous agitator 2, and a pressure regulator 6 provided in the pipe 5.

  Air is injected into the refractory slurry A by the compressed air introduction device 4. The compressed air introduction device 4 is inserted into the branch pipe portion 3a of the pipe 3 and fixed to the nozzle 41, a pipe 45 for supplying compressed air to the nozzle 41, and a flow regulator 46 provided in the middle of the pipe 45. It comprises. The nozzle 41 has a large-diameter main body portion 41a, a small-diameter tip portion 41b, a spherical portion 41c provided in the middle of the tip portion 41b, and a discharge port 42 provided near the tip of the tip portion 41b. A cylindrical rubber 43 is attached to the tip portion 41b of the nozzle 41, and the cylindrical rubber 43 is locked to the spherical portion 41c. In order to inject compressed air into the refractory slurry at a high speed, the opening diameter D of the discharge port 42 is preferably sufficiently smaller than the inner diameter of the pipe 3. For example, when the inner diameter of the pipe 3 is 15 mm, the opening diameter D of the discharge port 42 is preferably about 1 to 5 mm. The number of outlets 42 is not particularly limited, and a plurality of outlets 42 may be provided as necessary.

  As shown in FIG. 3 (a), when compressed air having a pressure higher than that of the refractory slurry A is fed to the nozzle 41, the cylindrical rubber 43 is slightly expanded, and from the gap between the tip 41b and the cylindrical rubber 43. Compressed air is continuously injected into the refractory slurry A. It is preferable to supply sufficiently high-pressure compressed air and inject it into the refractory slurry A so that the compressed air is in the form of bubbles. When the supply of compressed air is stopped, the cylindrical rubber 43 covers the discharge port 42 as shown in FIG. 3 (b), so that the refractory slurry A does not enter the nozzle 41. Thus, the cylindrical rubber 43 functions as a check valve.

  The amount of compressed air injection varies depending on the feed rate of the refractory slurry in the pipe, the viscosity of the refractory slurry, etc., so adjust the compressed air pressure so that the appropriate amount of air can be injected. Is preferred. The injection pressure of compressed air is preferably 0.1 Pa or more. If the injection pressure is less than 0.1 Pa, an appropriate amount of air may not be injected.

(2) Agitation of the refractory slurry In order to further refine the bubbles injected into the refractory slurry A by the compressed air introduction device 4, the refractory slurry is agitated and sheared. As long as the stirrer has a shearing force capable of refining bubbles in the refractory slurry, a batch stirrer or a device capable of continuous stirring may be used, but it is preferable to use a device capable of continuous stirring. . When using a continuous stirrer, as shown in FIG. 1, it is preferable to provide the continuous stirrer 2 at a position as close as possible to the compressed air introduction device 4 in order to suppress bubbles from being combined.

  As shown in FIGS. 4 (a) to 4 (c), the continuous agitator 2 has a cylindrical stator 20 having a large number of stator pins 20 a projecting radially inward from the inner peripheral surface, and rotates into the stator 20. A cylindrical rotor 21 having a large number of rotor pins 21a that are freely arranged and project radially outward on the outer peripheral surface, a cylindrical stator 20 and a sealed casing 25 that covers the cylindrical rotor 21, and a rotor 21 It has a motor 22 to be driven, an inlet 23 provided at one end of the casing 25, and an outlet 24 provided at the other end of the casing 25. The continuous stirrer 2 may be water-cooled or air-cooled as necessary.

  The stator pins 20a and the rotor pins 21a may be cylindrical or prismatic, but are preferably prismatic with excellent shearing force. The pins 20a and 21a are preferably formed of a wear-resistant material such as carbide, cermet, or ceramic in order to suppress wear. Since the rotor pins 21a and the stator pins 20a are alternately arranged in a narrow gap so as not to contact, the refractory slurry A having bubbles can be stirred while being sheared.

  In order to refine the bubbles by applying high shear to the refractory slurry A, the rotor 21 of the continuous agitator 2 is preferably rotated at a peripheral speed of 2 m / second or more, more preferably 3 m / second or more. If the peripheral speed is less than 2 m / sec, the shearing force is too weak and the bubbles may not be sufficiently refined. The upper limit of the peripheral speed of the rotor 21 is not particularly limited as far as technically possible. The residence time of the refractory slurry A in the continuous agitator 2 is set within a time during which the binder does not cure.

(3) Construction The heat-insulating amorphous refractory B having fine bubbles obtained by high-speed stirring with the continuous stirrer 2 can be applied by a casting method, a press-fitting method, or the like. In the casting construction method, as shown in FIG. 1, the casting can be poured directly into the mold 8 from the outlet of the pipe 5. However, since it is cumbersome to install the continuous agitator 2 at a construction site in a heating furnace or the like, as shown in FIG. 5, the hose 7 extending from the continuous agitator 2 to the construction site is arranged at a spaced position. It is preferable to pump the heat-insulating amorphous refractory B to the mold 8.

[4] Insulating refractory refractory body Insulating refractory B is a foam with an apparent porosity of 70 to 85% and a cumulative 80% diameter of 500μm or less when fired at 1,000 ° C for 3 hours. The construction body has a diameter distribution. When the apparent porosity is less than 70%, the heat insulating property of the construction body is insufficient, and when the apparent porosity exceeds 85%, the strength as the construction body decreases. When the cumulative 80% diameter exceeds 500 μm, not only the mechanical strength of the construction body is insufficient, but also the thermal stress relaxation effect (heat stress resistance) is insufficient.

  The relaxation effect of thermal stress can be evaluated using the deformation rate of the construction body as an index. Deformation rate is an index used for materials having both elastic and plastic deformation characteristics. The maximum load and displacement up to the maximum load point are obtained in the load-displacement curve, and the three-point bending test described in JIS R 1659 It is represented by a value calculated using the elastic modulus calculation formula in FIG. 1, and the smaller the value, the easier the stress relaxation, so the crack suppression effect is high. The deformation rate of the construction body is preferably 25 MPa or less.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1
A refractory composition comprising 30% by mass of calcined alumina fine powder (particle size of 45 μm or less), 30% by mass of spinel powder (particle size of 150 m or less), 10% by mass of magnesia fine powder (particle size of 200 μm or less) and 30% by mass of alumina cement; A pan-type forced kneading mixer (manufactured by Yusei Kenki Co., Ltd.) was prepared by mixing 1 part by weight and 30 parts by weight of sodium lauryl sulfate and an aqueous carboxymethyl cellulose solution (viscosity: 100 mPa · s) with respect to 100 parts by weight of the refractory composition. Refractory material slurry A was prepared by kneading for 1 minute at a peripheral speed of 1.38 m / sec.

  As shown in FIGS. 1 to 4, the refractory slurry A is pumped at 0.1 MPa by the pump 1, and compressed air is injected into the refractory slurry A from the compressed air introduction device 4 (the discharge port 42 of the nozzle 41 is With diameter D: 3 mm, air injection amount for 1 L refractory slurry A: 0.7 L, injection pressure: 0.12 Pa), continuous stirrer 2 (model: BM90, manufactured by Yana Gear Co., Ltd., rotor pin 21a and stator pin 20a The distance was 2.5 mm). The refractory slurry A introduced into the continuous stirrer 2 is continuously agitated with a residence time of 30 seconds (peripheral speed of the rotor 21: 4.7 m / second), and the heat-insulating amorphous refractory B having fine bubbles. Was prepared. The heat-insulating amorphous refractory B was poured into a mold, cured by curing for 24 hours, further dried at 110 ° C. for 24 hours, and then fired at 1,000 ° C. for 3 hours. A test piece was prepared from the fired construction.

Examples 2-4
Except for changing the air injection amount to 0.3 L, 1.0 L, and 1.2 L, respectively, in the same manner as in Example 1, a heat-insulating amorphous refractory construction body was produced to obtain a test piece.

Examples 5 and 6
A heat insulating amorphous refractory construction was prepared and tested in the same manner as in Example 1, except that the amount of carboxymethylcellulose aqueous solution added was 32 parts by mass and the viscosity was changed to 5 mPa · s and 200 mPa · s, respectively. I got a piece.

Examples 7 and 8
Except having changed the addition amount of carboxymethylcellulose aqueous solution into 25 mass parts and 40 mass parts, respectively, it carried out similarly to Example 1, produced the construction body of the heat-insulating amorphous refractory, and obtained the test piece.

Example 9
Except that the peripheral speed of the rotor 21 was changed to 2.0 m / sec, a construction body of a heat-insulating amorphous refractory was produced in the same manner as in Example 1 to obtain a test piece.

Comparative Example 1
Construction of heat-insulating amorphous refractory in the same manner as in Example 1 except that a composition comprising 70 mass% of fused alumina fine particles (particle size of 1 mm or less) and 30 mass% of alumina cement was used as the refractory composition. A body was prepared to obtain a test piece.

Comparative Examples 2 and 3
Except for changing the air injection amount to 0.2 L and 1.4 L, respectively, in the same manner as in Example 1, a construction body of heat-insulating amorphous refractory was produced to obtain a test piece.

Comparative Example 4
Except that the amount of the carboxymethyl cellulose aqueous solution added was changed to 34 parts by mass and the viscosity was changed to 1 mPa · s, in the same manner as in Example 1, a construction body of a heat insulating amorphous refractory was produced to obtain a test piece.

Comparative Example 5
Except that the amount of the carboxymethyl cellulose aqueous solution added was changed to 32 parts by mass and the viscosity was changed to 250 mPa · s, in the same manner as in Example 1, a construction body of a heat-insulating amorphous refractory was produced to obtain a test piece.

Comparative Examples 6 and 7
Except having changed the addition amount of carboxymethylcellulose aqueous solution into 23 mass parts and 45 mass parts, respectively, it carried out similarly to Example 1, produced the construction body of the heat-insulating amorphous refractory, and obtained the test piece.

  About the test piece produced in Examples 1-9 and Comparative Examples 1-7, the apparent porosity, thermal conductivity, compressive strength, the cumulative 80% diameter of a bubble, and a deformation rate were measured with the following method. The measurement results are shown in Table 1.

(1) Apparent porosity
Measured according to JIS R 2205.

(2) Thermal conductivity
Measured according to JIS R 2616.

(3) Compressive strength
Measured according to JIS R 2553.

(4) Cumulative 80% diameter of bubbles The cumulative 80% diameter is obtained from the bubble diameter measured by the following method, and the total number of bubbles is 100%. It was defined as the diameter of the bubbles. The bubble diameter was measured according to a crystal grain size measuring method (cutting method) generally performed in the engineering ceramics field. Specifically, a straight line across the image was drawn at an arbitrary position on the scanning electron micrograph of the cut surface of the test piece, and the length of the line segment across each bubble was defined as the diameter of each bubble.

(5) Deformation rate
Measured according to JIS R 1659. Specifically, using a test piece of length 160 mm x width 40 mm x thickness 32 mm, with autograph AG-50KNX (manufactured by Shimadzu Corporation), the load roll descending speed was set to 0.01 mm / min. From the load-displacement curve obtained by measurement, obtain the maximum load and the displacement to the maximum load point (the amount of descent of the load roll), and use the elastic modulus calculation formula in the three-point bending test as shown below. Was calculated.
Deformation rate = L ³ P / (4WT ³ Y) (MPa)
P: Maximum load (N)
L: Distance between support rolls (mm)
W: Specimen width (mm)
T: Specimen thickness (mm)
Y: Descent amount of load roll (mm)

  As is clear from Table 1, the construction bodies of Examples 1 to 9 had an 80% cumulative bubble diameter of 500 μm or less and an excellent deformation rate of 25 MPa or less. That is, it can be said that when the heat-insulating amorphous refractories of Examples 1 to 9 are used, it is easy to relieve stress and a construction body in which the occurrence of cracks is suppressed can be obtained.

  On the other hand, in Comparative Example 1 containing refractory fine powder having a particle size of more than 300 μm and Comparative Example 7 in which the addition amount of the kneading liquid is more than 40 parts by mass, the cumulative 80% diameter of bubbles is more than 500 μm, It is difficult to suppress the occurrence of cracks because the deformation rate is higher than 25 MPa. In addition, Comparative Example 2 in which the amount of air injected was less than 0.3 L with respect to 1 L of the refractory slurry, Comparative Example 4 in which the viscosity of the kneaded liquid was less than 5 mPa · s, Comparative Example 5 in excess of 250 mPa · s, and the kneaded liquid In Comparative Example 6 in which the amount of addition is less than 25 parts by mass, air cannot be sufficiently contained, so that the thermal conductivity is high and high heat insulation cannot be obtained. Comparative Example 3 in which the amount of air injected is more than 1.2 L with respect to 1 L of the refractory slurry has a low thermal conductivity and excellent heat insulation properties, but cannot obtain sufficient strength as a construction body.

1 ... Pressure pump 2 ... Continuous agitator
20 ... Cylindrical stator
20a ... Stator pin
21 ... Cylindrical rotor
21a ・ ・ ・ Rotor pin
22 ... Motor
23 ... Entrance
24 ... Exit
25 ... Case 3 ... Piping
3a ... Branch pipe part 4 ... Compressed air introduction device
41 ... Nozzle
41a ・ ・ ・ Main body
41b ・ ・ ・ Tip
41c ... spherical part
42 ... Discharge port
43 ... Tubular rubber
45 ... pipe
46 ... Flow rate regulator 5 ... Pipe 6 ... Pressure regulator 7 ... Hose 8 ... Formwork
A ... Refractory slurry
B ・ ・ ・ Insulating refractory

Claims (5)

Refractory composition comprising 60 to 90% by mass of refractory fine powder having a particle size of 300 μm or less, and 10 to 40% by mass of a binder, a foaming agent, a viscosity of 5 to 220 mPa · s, and an addition amount of the refractory composition 100 Insulation obtained by injecting 0.3 to 1.2 L of air per 1 L of the refractory slurry into the refractory slurry obtained by kneading 25 to 40 parts by mass of the kneading liquid with respect to part by mass, and stirring. It is an indeterminate shaped refractory, and it is characterized by becoming a construction body having an apparent porosity of 70 to 85% and a bubble size distribution with a cumulative 80% diameter of 500 μm or less by firing at 1,000 ° C. for 3 hours. Heat-insulating unshaped refractory. The heat insulating amorphous refractory according to claim 1, wherein the binder is alumina cement. Refractory composition comprising 60 to 90% by mass of refractory fine powder having a particle size of 300 μm or less, and 10 to 40% by mass of a binder, a foaming agent, a viscosity of 5 to 220 mPa · s, and an addition amount of the refractory composition 100 The refractory slurry obtained by kneading the kneading liquid that is 25 to 40 parts by mass with respect to part by mass is pumped to the continuous agitator through the pressure feeding pipe by a pressure feeding pump, and per 1 L of slurry to the refractory slurry. Insulating 0.3 to 1.2 L of air, and stirring the refractory slurry with the continuous stirrer to prepare a heat-insulating amorphous refractory having fine bubbles, the heat insulating property discharged from the continuous stirrer A method for constructing a heat-insulating irregular refractory, characterized by pouring an irregular refractory into a construction site. In the construction method of the heat-insulating amorphous refractory according to claim 3, the continuous stirrer has a cylindrical stator having a large number of stator pins on the inner peripheral surface, and a large number on the outer peripheral surface while rotating in the cylindrical stator. And the rotor is rotated at a peripheral speed of 2 m / sec or more to agitate the refractory slurry between the stator pin and the rotor pin, and thereby the refractory slurry in the refractory slurry. A construction method characterized by refining bubbles. The construction method of the heat-insulating amorphous refractory according to claim 3 or 4, wherein the binder is alumina cement.

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