JPH08253352A - Production of high-strength inorganic foam - Google Patents

Abstract

PURPOSE: To provide a method for producing a high-strength inorganic foam using new inexpensive and readily obtainable raw materials by blending (weath ered) granite fine powder with kaolinite-containing mineral fine powder and blowing agent fine powder, molding and baking. CONSTITUTION: A mixture is obtained by uniformly blending 100 pts.wt. of (weathered) granite fine powder ground into <=30μm average particle diameter with 5-50 pts.wt. of kaolinite-containing mineral fine powder having <=20μm average particle diameter and 0.1-3 pts.wt. of blowing agent fine powder and optionally further adding a molding auxiliary and pigment to the blend. The mixture is molded and baked at 1,050 to 1,250 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a high-strength inorganic foam which is advantageously used as an aggregate for lightweight concrete, fine sand for lightweight mortar, a fireproof coated plate such as a steel frame, a heat insulating plate for various structures, and the like. It is a thing.

[0002]

BACKGROUND ART Conventionally, as an inorganic foam product,
Volcanic glass such as shirasu, obsidian, and pearlite is crushed to a specified particle size, and this is heated and foamed alone, or expansive minerals such as expansive hirucite and expanded shale are crushed to a specified particle size. , Which is heated and expanded by itself, industrial waste such as coal mine slag, slag, sludge sludge, etc., is granulated and fired with pulverized coal, and rhyolite pumice such as anti-firestone It is known that the fine powder of (1) is granulated with a foaming agent such as silicon carbide and fired. And, these foamed granules have their respective characteristics, and are useful as aggregates for lightweight concrete, fine sand for lightweight mortar, lightweight fillers for various molded bodies, etc., and are currently produced in large quantities. .

However, in these conventional foams,
There are some inherent problems that are desired to be improved. That is, in these conventional foams, when the firing temperature is increased during the production, or in order to increase the degree of foaming, the amount of the foaming agent is increased to decrease the specific gravity and to make the foam lighter. In that case, there is a problem that the mechanical strength is extremely lowered. As a specific example, the specific gravity is 0.7 using each of the above raw materials.
Hereinafter, when a foam having a diameter of about 2 to 5 mm is produced and the foam is agitated and mixed with cement using a normal mortar mixer or the like, half or more of the particles are damaged, However, there is a problem that a lighter molded body cannot be obtained.

As a technique for solving the above problems, the inventors of the present invention have previously covered the surface with a porcelain skin layer made of a glassy mineral and a kaolinite-containing mineral, and the same inside. Completed the invention of high-strength inorganic foam granules, which has a structure in which minute bubbles are independently filled in the material innumerably, and a method for producing it advantageously, and filed a patent application for it. It was

However, in the invention for which this patent application has been made, when the glassy mineral used as a raw material is anti-firestone, there is a problem that transportation costs are high because the production areas are unevenly distributed. In the case of obsidian, the price is high due to the small amount of reserves, and in the case of various feldspars, since they are usually produced only in refined form, they are a very expensive raw material like obsidian. Each had problems such as unavoidable problems.

[0006]

The present invention has been made in view of such circumstances, and the problem to be solved is to make it easier to realize the invention previously proposed by the present inventors. (EN) It is possible to provide a method for producing a high-strength inorganic foam using a new raw material, which is possible, inexpensive and easily available.

[0007]

The present inventors have made further studies in order to solve such a problem, and as a result, have a chemical composition similar to that of feldspar and their reserves are feldspar. It is abundant in the above and is widely distributed in the country, and it is not necessary to separate and remove impurities and the like, and only by crushing the raw ore just mined and washed with water, the patent of the present inventors The present invention has been accomplished by finding a mineral that has the same effect as that used in the application.

That is, in order to solve the above-mentioned problems, the present invention uses 100 parts by weight of fine powder of granite or weathered granite and one or two selected from kaolinite-containing minerals such as clay, kaolin and gravel shale. 5 kinds of fine mineral powder
1 part by weight or more and 50 parts by weight or less and 0.1 parts by weight or more and 3 parts by weight or less of a blowing agent fine powder such as silicon carbide or silicon nitride are uniformly mixed, and if necessary, bentonite, wax, Molding aids such as modified cellulose powder and pigments such as red iron oxide are further mixed, and the resulting mixture is molded into a predetermined shape and then fired at a temperature of 1050 ° C to 1250 ° C. The gist of the invention is a method for producing a strong inorganic foam.

[0009]

[Specific Structure / Operation] By the way, such a granite or weathered granite used in the present invention is composed of quartz, feldspar, mica, etc. as its constituent minerals, and the abundance ratio of each is quartz. It is general that the ratio is about 40%, feldspar is about 55%, and mica is about 5%. The production areas are distributed throughout the country, and are classified into various brands according to the type of trace ingredients and the color difference, but the basic composition does not change greatly, and whichever one is used. Also, the present invention can be easily implemented.

Among them, in particular, weathered granite has a characteristic that it is easily crushed into granules. Therefore, the granules are finely crushed, and then various steps are performed to remove quartz grains and mica grains. It is also practiced to remove and remove feldspar. However, when applied to the present invention, all of these purification steps are unnecessary, thus providing a more economical raw material. Among the weathered granite produced in each of these areas, the ones called "Muso-silk" and "Sabo" collected in Gifu and Aichi prefectures have a moderate degree of weathering and a grain size of 1 Since it is about 20 mm, it can be said that it is a highly practical raw material because it is easy to pulverize the raw material when carrying out the present invention.

[0011] The usual granite is cut out and used as a building material, a gravestone, etc., but chips and the like generated during such processing can also be used advantageously in the present invention. .

Further, the kaolinite-containing mineral used in the present invention is a common name, and in addition to kaolinite in terms of mineralogy, minerals mainly composed of hydrolyzed halloysite, halloysite, deckite, nacrite and the like, and kaolin minerals are mainly composed. It is intended to mean kaolin clay. Concretely, clays called China clay, Georgia clay, etc., gravel shale, frog clay, etc., and any of these may be used, or some of them may be mixed. Even if used, the object of the present invention can be sufficiently achieved.

Further, as the foaming agent used in the present invention, there are silicon carbide, silicon nitride and the like, and the same conventional ones used for refractory materials or various ceramics can be appropriately used. It should be noted that, although not particularly limited, a smaller particle size is preferable in order to uniformly distribute a large number of air bubbles inside the product. Specifically, the average particle size is 5 μm or less, more preferably 1 μm or less.

In carrying out the present invention,
The means for crushing the raw material granite grains or the weathered granite is not particularly limited, but the average particle diameter of the crushed raw material powder is preferably 30 μm or less. This is because when the average particle size exceeds 30 μm, unreacted silica stone particles are likely to appear on the surface of the resulting foam or on the wall separating the air bubbles, and the specific gravity becomes a little large. This is because there will be a problem of a slight decrease.

The particle size of the kaolinite-containing mineral powder which is another main raw material of the present invention is different from that of granite and weathered granite due to the function of the kaolinite-containing mineral powder described later. As fine as possible, specifically, an average particle size of 20 μm or less, particularly preferably 10 μm.
It is desirable to use those of m or less.

That is, the kaolinite-containing mineral of the present invention has two functions. One of them is that when a mixture of granite, weathered granite powder and a foaming agent is integrated with water or the like and granulated. , For imparting plasticity to such a mixture, and the other one is to enhance the melt reactivity with granite powder and weathered granite powder, and to rapidly and porcelain composition constituting the foam object of the present invention, This is for surely forming it. For these reasons, the particle size of the kaolinite-containing mineral powder used in the present invention needs to be made finer than that of granite powder or weathered granite powder. The aluminum compound forms a layer and is characterized in that it can be easily crushed. Therefore, there is practically no problem in crushing such a kaolinite-containing mineral.

Further, in the present invention, the method for molding a mixture of granite powder or weathered granite powder, kaolinite-containing mineral powder, and blowing agent powder is not particularly limited, and the molded body thereof is not limited. The shape is not particularly limited. For example, as a molding method,
All known methods such as an extrusion molding method, a tumbling granulation method, and a crushing granulation method in which a kneaded product is dried and crushed are applicable. Further, the shape of the molded body is also plate-like, rod-like, spherical, etc.
Either of them can be adopted, and by firing thereof, foams having a similar shape to them can be obtained.

Furthermore, the method of mixing the respective raw material powders when carrying out the present invention is not particularly limited, and the mixing means may be selected according to the wet state of the respective raw material powders. Specifically, a method such as a V-blender, a kneader, or a method in which crushing and mixing are simultaneously performed by a ball mill may be adopted.

In the present invention, if necessary, a molding aid, a pigment or the like can be used in the above-mentioned granulation molding according to a conventional method. Specifically, examples of the molding aid include bentonite for increasing the strength of the molded product before firing and foaming, modified cellulose powder, and various waxes for the purpose of increasing the fluidity of the kneaded product during extrusion molding. Further, pigments such as red iron oxide for coloring the foam can be mentioned.
In addition, the amount of these additives is usually about several percent of the total amount, and does not influence the effect of the present invention.

Here, the substance constituting the foamed product obtained according to the present invention is a porcelain composed mainly of the feldspar component of granite and weathered granite and the kaolinite-containing mineral, and is usually porcelain. Although it is of the same quality as the porcelain used in the tableware and tiles, the starting temperature for melting porcelain is somewhat lower than that for normal porcelain because of the large amount of feldspar components. That is, the usual porcelain is as strong as possible, and at the same time, fusion during firing,
In order to prevent deformation, many are designed so that the content of the kaolinite-containing mineral is high and the firing temperature is around 1250 ° C. In the present invention, this temperature is set to silicon carbide, silicon nitride or the like. The foaming agent is efficiently decomposed in a short time at a temperature of 1050 ° C to 1250 ° C, and the calcined body has a sufficient viscosity at the calcining temperature, so that the generated bubbles are crushed and the composition balance is designed to prevent escape. There is.

Although different from the present invention, a mixture of fine powder of granite or fine powder of weathered granite and fine powder of a foaming agent such as silicon carbide is molded by any method, and the molded product is A foam can be obtained by firing as in the invention. However, on the surface of the foam thus obtained, air bubbles are crushed, resulting in severe irregularities, and unlike the foam of the present invention, a foam having a low specific gravity cannot be formed. That is, it means that in such a system, the viscosity of the melt is low, and the melt encloses the gas generated by the foaming agent so that the shape cannot be maintained. Further, this is because the action of the kaolinite-containing mineral used in the present invention is very important, and the decomposition reaction temperature of the foaming agent and the viscosity of the porcelain produced at that temperature are the gas generated by the foaming agent. It shows that it is just right to wrap around.

Therefore, the blended composition of the present invention is
When fired at a temperature exceeding 250 ° C., the diameter of the bubbles existing inside the obtained foam becomes large, and the thickness of the porcelain material constituting the bubble wall around and inside the foam becomes extremely thin. At the same time, the mechanical strength is lowered, and only a foam having low practicality can be obtained. However, in order to prevent this, if the mixing ratio of the kaolinite-containing mineral is increased beyond the range of the present invention, the strength of the resulting foam becomes strong, but the specific gravity becomes extremely large, and the object of the present invention is It is not possible to obtain a lightweight foam.

On the contrary, the compounded composition of the present invention is
Firing at a temperature of less than 0 ° C. results in an extremely low foaming rate, making it a non-practical method.

In the present invention, with respect to the raw material composition which gives the desired high-strength inorganic foam, 5 to 50 parts by weight of the kaolinite-containing mineral powder, preferably 100 parts by weight of the granite powder or the weathered granite powder is preferable. It is necessary to limit the blending ratio to 10 to 35 parts by weight. This is because if the content of the kaolinite-containing mineral is less than 5 parts by weight, various molding operability will be deteriorated, and in addition, the mechanical strength of the foam obtained by firing this will be extremely reduced. is there.

When the kaolinite-containing mineral is blended in a proportion of more than 50 parts by weight, the moldability is improved, but the degree of foaming of the foamed granules is lowered, and the same amount of the foaming agent is used for firing at the same temperature. However, a foam having an extremely large specific gravity cannot be obtained. It is considered that this is because the melting porcelainization start temperature required for foaming becomes high, and the reaction decomposition temperature of the foaming agent such as silicon carbide or silicon nitride is exceeded.

The specific gravity of the foam obtained according to the present invention can be controlled by two methods. One of them is the amount of foaming agent to be blended, and if this amount is increased,
As a result, the number of bubbles created in the foam particles increases, and as a result,
The specific gravity of the foam becomes small. The other is to change and control the firing temperature. This is because when the firing temperature is increased, the diameter of the bubbles in the foam increases, and as a result, the specific gravity of the foam decreases.

[0027]

EXAMPLES In order to clarify the present invention in more detail, some examples of the present invention will be shown below.
It goes without saying that the present invention is not limited by the description of such embodiments. In addition to the following embodiments, the present invention is not limited to the above specific description, and various changes and modifications are made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It is to be understood that improvements, etc. can be added.

Examples 1 to 5 First, the granite and the weathered granite were crushed with a jaw crusher, respectively, and then crushed with a roll breaker to a particle size of 2 mm or less, and then finely crushed with an ordinary ball mill for 24 hours. The average particle size of each of the obtained powders was measured by an ordinary laser diffraction type particle size distribution meter and found to be 2
It was 5 μm and the weathered granite powder was 24 μm.

The average particle size of each of the frog eye clay (water-containing cake dehydrated by the filter press after the elutriation) and kaolin (water-containing cake dehydrated by the filter press after the elutriation) was imported from China. Was measured in the same manner as above, and it was 2.2 μm for frog eye clay and 3.3 μm for kaolin.

For each of the above mineral powders (granite powder / weathered granite powder, kaolinite-containing mineral), silicon carbide powder (Yakushima Electric Co., Ltd., average particle size 0.6 μm) and bentonite powder (for castings) (Standard product) and water were mixed in the proportions shown in Table 1 below, and kneaded with a kneader for 10 minutes,
A homogeneous plastic blend was made. The amounts of frog clay and kaolin used in Table 1 are shown as values obtained by removing water from the hydrous cake, and the amount of water is a value including the amount of the hydrous cake.

Next, each of the thus obtained kneaded products is molded by a usual method using a vacuum extruder and dried by a hot air dryer, and has a length of 50 cm, a width of 25 cm and a thickness of 2 c.
A m-shaped plate was prepared.

Then, each of the above-mentioned dried plate-like materials was fired in an electric furnace under the conditions of temperature rising rate: 200 ° C./hour, maximum temperature: 1200 ° C., holding time: 2 hours, and temperature lowering rate: 100 ° C./hour. did. Each of the foams obtained by the above firing operation had a shape similar to the shape before firing, and the specific gravity of each foam was as shown in Table 1 below.

[0033]

[Table 1]

Comparative Example 1 In this comparative example, the granite fine powder used in the previous examples: 1
00 parts by weight, bentonite powder: 5 parts by weight, and silicon carbide fine powder: 0.3 parts by weight were kneaded together with water in a kneader, and then the kneaded product was filled into a wooden frame to carry out molding. A plate-like material having a size of 50 cm, a width of 25 cm, and a thickness of 2 cm was obtained. This plate-like material was dried with a drier and weighed to find that it was 2.70 kg.

When the above-mentioned dried plate-like material was fired under the same conditions as in the above-mentioned examples, the surface of the obtained fired body had innumerable traces of the escape of bubbles and the inside The number of bubbles was smaller than that of the example, and the size was not uniform.

By the way, the shape of the fired body obtained in this Comparative Example has more distortion than that obtained in the above Examples, and it is difficult to measure the outer dimensions to obtain the volume thereof. The volume was measured by the water immersion method. as a result,
The volume of the fired body was 180 milliliters. Therefore, the specific gravity of the fired body was 1.50, and it was found that the foaming degree was lower than that in the above-mentioned Examples.

Comparative Example 2 First, anti-fire stone was crushed to prepare fine powder having an average particle size of 30 μm. Next, 100 parts by weight of such fine powder, 20 parts by weight of dry powder of frog clay (average particle size: 2 μm), 3 parts by weight of bentonite powder, and silicon carbide fine powder (average particle size:
0.6 μm) and 26 parts by weight of water,
The mixture was kneaded using a kneader, and the obtained kneaded product was extrusion-molded in the same manner as in the above-mentioned example and then dried by a hot air drier to have a length of 50 cm and a width of 25 cm.
A plate-like material having a thickness of 2 cm was produced.

Then, each of the above-mentioned dried plate-like materials was fired in an electric furnace under the conditions of temperature rising rate: 200 ° C./hour, maximum temperature: 1200 ° C., holding time: 2 hours, and temperature lowering rate: 100 ° C./hour. did.

The foam thus obtained had a shape similar to the shape before firing, and its specific gravity was 0.65.

[0040]

As is apparent from the above description, according to the method of the present invention, in producing a high-strength inorganic foam, it is possible to use a low-cost granite or a low-cost granite without using a high-cost volcanic glassy mineral such as feldspar. Using weathered granite, it is possible to advantageously obtain an inorganic foam equivalent to a volcanic glassy mineral and a kaolinite-containing mineral, and there is a great technical significance of the present invention. It is a thing.

Claims (1)

[Claims] 1. Granite or weathered granite fine powder 100
Parts by weight, and 5 parts by weight or more and 50 parts by weight or less of fine powder of one or more kinds of minerals selected from kaolinite-containing minerals such as clay, kaolin, and shale shale, and silicon carbide, silicon nitride, etc. 0.1 parts by weight or more and 3 parts by weight or less of the fine powder of the foaming agent are uniformly mixed, and if necessary, a molding aid such as bentonite, wax, modified cellulose powder or a pigment such as red iron oxide is further mixed. After molding and shaping the obtained mixture into a predetermined shape, 1050 ° C to 1250
A method for producing a high-strength inorganic foam, which comprises firing at a temperature of ° C.