JPS5841752A - Manufacture of refractory heat-insulating material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a fire-resistant insulation/thermal material, and more specifically, the present invention relates to a method for producing a fire-resistant insulation/thermal material. The present invention relates to a method for producing a fire-resistant heat insulating material, and a method for producing a fire-resistant heat insulating material that utilizes the combustion heat of rice husk generated when obtaining rice husk ash in the production of the fire-resistant heat insulating material.

There are many types of calcium silicate hydrates, but those that are generally used as fireproof insulation materials are mainly xonotrite and tobermorite, which are both made from silicic acid raw materials and lime raw materials. is obtained by hydrothermal reaction in the presence of water, usually under pressure.

By the way, the fire resistance performance of fire-resistant insulation materials varies depending on the type of calcium silicate hydrate, which is the main constituent. Zonotlite, which has a small shrinkage rate during transition, exhibits far superior heat resistance performance compared to the tobermorite group. This can be seen by comparing the heat resistance of commercially available refractory heat insulating materials, showing superior heat resistance of 650° C. for tobermorite-based materials and 50° C. for xonotrite-based materials.

Examples of silicic acid raw materials for this type of fireproof insulation include quartz,
Silica sand, white clay, diatomaceous earth, silica dust, etc. are widely used, but in particular, for the production of xonotlite-based fire-resistant insulation materials with excellent fire resistance, materials with a high silicon dioxide (Sin) content and a large specific surface area are used. It is necessary to use large silicic acid raw materials, such as finely ground quartz, finely ground volcanic amorphous silicic acid, silica dust,
Examples include white carbon. However, this
These raw material resources have drawbacks such as localization, which limits the location requirements for commercialization, and high prices.

In order to overcome these drawbacks, the present inventors have conducted intensive research into a method for producing xonotrite-based fireproof insulation materials that are made from inexpensive and easily available silicic acid resources. The ash obtained by burning rice husk is the best silicic acid resource for this purpose, and the calorific value when burning rice husk is approximately 33Q per IKy of rice husk.
Since the amount of heat reaches QKca'l, it was discovered that this amount of heat could be effectively used as a heat source during the production of fireproof insulation materials, and based on this knowledge, the present invention was completed.

That is, the present invention provides a fire-resistant insulation material characterized in that rice husk ash and lime raw material are suspended in water and subjected to a hydrothermal reaction, and the resulting calcium silicate hydrate crystals are shaped and dried. A method for producing fire-resistant heat insulation, characterized by suspending rice husk and lime raw materials in water, pouring into a mold, putting it in an autoclave as it is or after demolding, and curing by heating under saturated steam pressure. In manufacturing the refractory insulation material using these manufacturing methods, the combustion heat of rice husk generated when obtaining rice husk ash is used as a heat source necessary for manufacturing the refractory insulation material. The present invention provides a method for manufacturing a fireproof heat insulating material.

The rice husk ash used as a raw material in the present invention is obtained by burning rice husk in an oxidizing atmosphere at a yield of about 20% of its weight. This rice husk can be used regardless of its origin, and in order to increase the silicon dioxide content, it can be calcined in an oxidizing atmosphere so that no combustion carbon remains and the resulting ash becomes white. desirable. The silicon dioxide content in the ash thus obtained reaches 190-odd units.

When burning rice husk, the type of silica obtained by keeping the baking time constant at 2 hours and changing the baking temperature from 400℃ to 1000℃ was investigated by X-ray diffraction, and it was found that 400-60
At a firing temperature of 0°C, amorphous silica was obtained, at 800°C a part of this amorphous silica crystallized into cristobalite, and at 1000°C, a mixture of cristobalite and tridymite was formed. Also increase the temperature to 800
When the firing time was varied from 1 hour to 16 hours while keeping the temperature constant at °C, it was amorphous silica up to 2 hours, but crystallization to cristobalite started after 4 hours, and cristobalite and tridymite were formed within 8 to 16 hours. It crystallized into a mixture of

In other words, silicon dioxide in rice husk ash tends to become amorphous silica when the firing temperature is low or the firing time is short, and when the firing temperature is high and the firing time is long, it tends to crystallize into tridymite and cristobalite. It has a characteristic that it is difficult to crystallize into quartz, which has a stable crystal structure. These amorphous silica, tridymite, and cristobalite all have much higher hydrothermal reactivity than quartz, and compared to quartz raw materials normally used for the synthesis of calcium silicate hydrate. It can be said that it is an extremely excellent raw material.

Furthermore, the ash obtained by burning rice husks retains the form of the rice husks before burning and is porous and has a high specific surface area, so it is characterized by extremely high pulverizability.

By the way, all silicic acid raw materials used for fireproof insulation materials must be used in the form of fine powder, and the conventionally used silicic acid raw materials have a low pulverizability, so they have the disadvantage that the pulverization cost is quite high. However, if rice husk ash is used as the silicic acid raw material, the grinding cost can be significantly reduced due to its high pulverizability.

The lime raw material, which is the other raw material in the method of the present invention, must contribute to the reaction as calcium hydroxide Oa (OH), and examples of such materials include slaked lime, quicklime, and carbide slag.

The hydrothermal reaction in the method of the present invention includes two methods: (1) a method in which finely ground rice husk ash and lime raw materials are uniformly dispersed in water, and (CB) a method in which a mixed slurry of these raw materials dispersed in water is used in a mold. There are two methods: pour it into a mold and do it as is or after removing it from the mold.

In these methods, the blending ratio of rice husk ash and lime raw materials varies depending on the type of calcium silicate hydrate that is desired, but when the purpose is to produce xonotlite, Ca/Si
The molar ratio is preferably in the range of 0.8 to 1.2, and 0.5 to 1.0 if tobermorite type is desired.The optimum blending ratio of rice husk ash and lime raw material is determined by the ratio of rice husk ash and lime raw material. The Ca/Si molar ratio varies depending on the grain size and crystallinity; if the grain size is very small, the Ca/Si molar ratio should be slightly larger, and if the crystallinity is high, the Ca/Si molar ratio should be slightly larger.

In addition, in order to obtain the desired product performance, it is necessary to add conventional silicic acid raw materials such as quartz, silica sand-clay, aluminosilicate raw materials, reinforcing fibers, shirasu balloons and perlite to the rice husk and lime raw material mixture. You may add lightweight fillers such as.

Examples of reinforcing fibers include asbestos, rock wool J-lass fiber, ceramic fiber, carbon fiber, metal fiber, pulp, cotton,
Various synthetic fibers can be used alone or in combination.

In method (A) (7) in the hydrothermal reaction, in order to promote crystal growth of the produced calcium silicate hydrate, it is preferable to keep the slurry concentration low. ) Calcium silicate hydrate is produced by placing the mixture in a reaction vessel such as aclave, heating it to a temperature of usually 140C or higher, and holding it for several hours. In this case, in order to obtain xonotrite crystals, the reaction temperature must be set at 18o~260'
It is desirable to set it within the range of C. The purpose of stirring in this reaction is to keep the reaction system homogeneous and promote crystal growth, so it is desirable to stir constantly, but if desired, stir only at the beginning of the reaction to form a single layer of uniform slurry. Alternatively, a method may be used in which the stirring is completely stopped and the crystal growth is allowed to occur while the mixture is left standing.

After this hydrothermal reaction, the slurry is further mixed with the above-mentioned reinforcing fibers, lightweight fillers, etc. as needed, molded into a desired shape, and then dried to obtain the desired fireproof heat insulating material. As a molding method, commonly used methods such as casting molding, pressure molding, paper molding, extrusion molding, etc. can be used. Further, in order to improve moldability, inorganic materials such as clays, Portland cement, and lime, and N/M such as resin emulsions and methylcellulose may be added.

In addition, in method (B) for hydrothermal reaction, the raw material blend slurry is poured into a mold, either as it is or after being demolded, placed in an autoclave, heated and cured under saturated steam pressure, and then dried to achieve the desired purpose. Obtain a fire-resistant insulation material.

In this method, in order to prevent settling of the slurry in the mold, it is desirable that the rice husk ash be particularly finely pulverized and a viscosity imparting agent such as a certain type of clay or resin emulsion be added.

Furthermore, in the uninvented manufacturing method, the combustion heat of rice hus generated when obtaining rice husk ash (rice husk I
You can make effective use of the amount (approximately 3,300 keels). Therefore, manufacturing costs can be significantly reduced.

The rice husk ash used in the present invention is inexpensive, easily available, easy to crush, and is an excellent silicic acid resource with high hydrothermal reactivity. A fire-resistant insulation material with low heat resistance can be obtained. Furthermore, in the uninvented manufacturing method, the heat of combustion of rice husk generated when obtaining rice husk ash can be effectively utilized. Therefore, the method of the present invention can be said to be an extremely economically valuable method that effectively utilizes both the combustion heat of rice husk and ash, which are agricultural wastes.

Next, the invention will be explained in more detail with reference to Examples.

Example 1 When rice husk was baked at 600° C. in an oxidizing atmosphere, white amorphous rice husk ash was obtained. Its SiO□ content M ratio was 93.0ch. Grind this to a particle size of 20 μm or less, mix quicklime so that the Oa/81 molar ratio is 1.0, add 24 times the amount of water on a weight basis, and place it in an electromagnetic stirring autoclave at n1 stirring speed of 300 rpm.
When the reaction was carried out at 190°C for 8 hours, well-developed needle-shaped xonotrite crystals were obtained. For reinforcement, asbestos was added to the slurry in an amount of 10% by weight based on the solid content in the slurry, and after uniformly dispersing the slurry, it was poured into a frame, pressure molded at 5 Kp/d, and dried at 60°C. A lightweight cured product of 0.25 was obtained. When the linear shrinkage rate of the cured product was measured under heating, it was 0.5% at a heating temperature of 700°C.
, 0.7 East at 850°C and 0.7 East at 1000°C, and this cured product was a fireproof heat insulating material with excellent dimensional stability.

Example 2 A cured product was obtained in the same manner as in Example 1 except that the molding pressure in Example 1 was changed to 20 to 9/aA.

The obtained cured product has a bulk specific gravity of 0.43, and the linear shrinkage rate of this cured product under heating is 0.43 at a heating temperature of 700°C.
6%, 0.6% at 850°C, and 0.7% at 1000°C, making it an excellent fireproof and insulating material.

Example 3 When the rice husk ash used in Example 1 was further heated at 800°C for 1 to 16 hours, the amorphous silica constituting the rice husk ash crystallized into cristobalite and tridymite as the heating time became longer. It became. When the obtained rice husk ash was pulverized under the same conditions, the heating time became longer and the crystallized rice husk ash had a lower pulverizing ability and a larger average particle size. For each of the finely pulverized rice husk ash, a lightweight cured product was molded and dried under the same conditions as in Example 1, and the bulk specific gravity and linear shrinkage rate under heating were measured. The insulation was removed.

Note that the hydrothermal reaction product was identified by X@ powder diffraction method. A regarding crystal morphology with narrow symbols.

C2T represents the raw HX and t- of amorphous silica, cristonolite, and tridymite, respectively;

Example 4 Rice husk ash crystallized into cristobamorite and tridymite was finely pulverized, and a cured product was produced in the same manner as in Example 1 except that the raw material blend Oa/'Eli molar ratio was changed from 0685 to 1.0. Obtained. The performance of the obtained cured product is shown in Table 2.

Note that the symbols in the table have the same meanings as in Example 3.

Patent Applicant Makoto Ishiita, Director of the Agency of Industrial Science and Technology (Government Office Procedures) Proceedings Amendment Document January 3, 1981 Indication of the Case of Tonoichi Haruki Shimada, Commissioner of the Patent Office 1981 Patent Application No. 1f6Fl'1,
Name of the invention Relationship to the case of a person amending the manufacturing method of fireproof insulation materials Patent applicant Makoto Ishiita, Director of the Agency of Industrial Science and Technology, 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (114) -- Number of inventions increased by the amendment 0, Subject of amendment Column 8 of Detailed Description of the Invention, Contents of amendment (1) In the 3rd page, line 14 of the specification, "-850 for the xonotrite series" is corrected to "--1000 for the xonotrite series."

(2) On page 9, line 5, "-1, slurry concentration is low, 1-1" is corrected to [-, slurry concentration is high, 1-1].

October 12, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office1, Indication of the case, Patent Application No. 116874, filed in 1982,2, Name of the invention, Method for manufacturing fireproof insulation material3, Person making the amendment, Relationship to the case Patent Applicant Makoto Ishizaka, 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (114) Director-General of the Agency of Industrial Science and Technology -4, Designated Agent Voluntary 6 Number of inventions increased by amendment 0 8 Contents of amendment (1) Description No. On page 6, line 9, change “up to 2 hours” to “
"Up to 1 hour" and "4 hours" in lines 9-10 of the same page should be changed to "2 hours."

(2) "It was..." on page 12, line 11.
Next to ``Example 2'', insert a new line and add the following sentence. Manufactured.

The cured product thus obtained has a bulk specific gravity of 0.29.
Moreover, the linear shrinkage rate under heating at different temperatures is as low as 0 at 650°C, 0.8% at 850°C, and 0.8% at 1000°C, indicating that it is an excellent fire-resistant heat insulating material. It was. (3) "Example 2" in the 12th line of the same page 12 is corrected to "Example 3" (4) "Example 3" in the 1st line of the same page 13 is changed to "Example 4" Correct.

(5) "X-ray powder diffraction method" at the bottom of page 13
will be corrected to "X-ray powder diffraction method".

(6) "Example 4" in the first line of page 15 will be corrected to "Example 5," and "Example 3" in line 7 of the same page will be corrected to "Example 4."

(7) Add the following sentence next to Table 2 on page 16.

1 Example 6 Quicklime was mixed with finely ground rice husk ash crystallized into cristobalite and tridymite so that the Ca/si molar ratio was 1.0, and 4 to 6 times the solid weight of water was added. The slurry was thoroughly stirred to form a homogeneous slurry, poured into a mold, and cured in an autoclave at 190°C under saturated steam pressure for 24 hours. When dried at 60°C, a cured product with a bulk specific gravity of 0.5 was obtained. This cured product was based on xonotlite, which has high heat resistance. ” (8)
“Cristobalite” in the second line of page 15 is “
Cristobalite” has been corrected.

Claims (1)

[Claims] 1. Rice husk ash and lime raw material are suspended in water and subjected to a hydrothermal reaction, and the obtained calcium silicate hydrate crystal f is formed,
A method for producing a fireproof insulation material characterized by drying. 2. The method according to claim WJ1, in which a mixture of rice husk and lime raw materials is added with a silicic acid raw material, an aluminosilicate raw material, reinforcing fibers, and a lightweight filler. 3. A method for producing a refractory/thermal material, which comprises suspending rice husk and lime raw material in water, pouring the suspension into a mold, and heating and curing it in an autoclave either as it is or after demolding, under n1 saturated steam pressure. 4 Claims @3 in which at least one selected from silicic acid raw materials, aluminosilicate raw materials, reinforcing fibers, and lightweight fillers are mixed into the rice husk and lime raw material mixture.
The method described in section. 5. Rice husk ash and lime raw material J are suspended in water and subjected to hydrothermal reaction to obtain silica-calcium hydrate crystals'! 1-J
Either the rice husk ash and lime raw material are suspended in water and poured into a mold, either as is or after being demolded, placed in an autoclave and then dried under saturated steam pressure. A fire-resistant insulation material characterized in that the heat of combustion from rice husks generated when obtaining rice husk ash is used as a heat source necessary for manufacturing the fire-resistant insulation material by heating and curing it in the process. Method of manufacturing wood.