JP4763942B2 - Inflated vermiculite for molding and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a mineral-derived porous swelling material characterized by lightness, heat insulation and high water retention.
[0002]
[Prior art]
Expanded vermiculite is a mineral-derived porous expanded material generally produced by expanding a hydroxyl group or crystal water contained in the crystal structure of vermiculite ore. Since this is characterized by excellent lightness, heat insulation, high water retention and ion exchange properties, it is frequently used for industrial materials, building materials, heat insulation materials, packing materials and artificial soil molded products.
[0003]
As a method of swelling, a method of rapidly heating vermiculite ore to a temperature of about 800 ° C. or more is most common, but such rapid heating to a high temperature requires very high energy.
[0004]
As another method, Japanese Examined Patent Publication No. 55-6600 proposes a method in which vermiculite ore is subjected to hydrogen peroxide in the presence of an acid and expanded at a temperature of 100 ° C. or lower. According to the method described in Japanese Patent Publication No. 55-6600, energy can be saved because it can be expanded at a lower temperature. However, since an acid of about 5% by weight is caused to act on the weight of the raw vermiculite, the pH of the vermiculite after the expansion is significantly lower than that obtained by the high temperature rapid heating method. Since the low pH swelling material is not suitable for plant growth, it cannot be used for the production of artificial soil molded products, and may be a factor that limits the application.
In addition, the method described in Japanese Patent Publication No. 55-6600 requires about 3.5 to 45% by weight of water based on the weight of the raw vermiculite, and it takes time to obtain a desired swelling ratio. It is a cause of delay.
[0005]
[Means for Solving the Problems]
As a result of intensive research, the inventors have conducted an exothermic reaction when vermiculite ore is expanded by the action of an iron compound and hydrogen peroxide in the presence of concentrated sulfuric acid or concentrated hydrochloric acid, and the maximum temperature Was found to reach about 90 ° C. or higher. Furthermore, the present inventors can reduce the amount of high-concentration acid used, so that the pH value of the resulting expanded vermiculite can be further increased, there is no need to add water as an essential component, and hydrogen peroxide water is further added. It has been found that the time until the desired expansion rate can be obtained can be greatly shortened by warming the system before adding, and the present invention has been completed.
That is, according to the present invention, the vermiculite ore is mixed with 0.05 to 0.5 mol of concentrated sulfuric acid or concentrated hydrochloric acid with respect to 1000 g of the vermiculite ore and 0.1 to 0.5% by weight based on the weight of the vermiculite ore. A method for producing expanded vermiculite, wherein an amount of an iron compound is added and mixed, the mixture is kept at a temperature of 40 to 100 ° C. for a certain period of time, then cooled, and then hydrogen peroxide solution is added to expand the mixture. It is.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing the expanded vermiculite of the present invention basically comprises the following three steps as shown in FIG.
Step 1: Step of adding concentrated sulfuric acid or concentrated hydrochloric acid and iron compound to vermiculite ore Step 2: Step of cooling after holding at a temperature of 40 to 100 ° C. for a certain time Step 3: Adding vermiculite by adding hydrogen peroxide Process of expanding the rough stone [0007]
Process 1
In the present invention, first, a high concentration acid and iron compound are added to the raw vermiculite.
The raw vermiculite used may be so-called ion exchange vermiculite produced by exchanging magnesium ions in vermiculite with cations such as sodium ion and ammonium ion, and these may be colored or dyed. . The size of the raw vermiculite varies depending on the purpose of use of the expanded vermiculite to be produced, but normally, those of No. 0 (about 0.1 mm square) to No. 4 (about 7 mm square) are preferably used.
[0008]
It is known from Japanese Patent Publication No. 55-6600 that the higher the concentration of the acid added to the vermiculite ore, the higher the expansion rate of the vermiculite ore. In the present invention, 95-98% concentrated sulfuric acid or 35% or more concentrated hydrochloric acid, which is usually commercially available, is used as the acid. Most preferably, about 98% concentrated sulfuric acid is used.
The amount of concentrated sulfuric acid or concentrated hydrochloric acid to be added is determined depending on the type of iron compound described later, but is generally less than that of the conventional method, and preferably 0.05 to 0.00 with respect to 1000 g of raw vermiculite. The amount may be 5 mol, preferably 0.1 to 0.3 mol based on 1000 g of the raw stone.
[0009]
At the same time or after the addition of the concentrated sulfuric acid or concentrated hydrochloric acid to the raw vermiculite ore, an iron compound is added, and these are stirred and mixed. Most preferably, the iron compound is added to a mixture of vermiculite ore and concentrated sulfuric acid or concentrated hydrochloric acid and mixed with stirring.
[0010]
The iron compound that is a characteristic component of the present invention may be at least one selected from ferrous sulfate, ferric sulfate, ferrous chloride, and ferric chloride. The iron compound may be a hydrate.
[0011]
Most preferably, ferric sulfate is used as the iron compound.
[0012]
The iron compound is added in an amount of 0.1 to 0.5% by weight, more preferably 0.2 to 0.3% by weight, based on the weight of the vermiculite used. The effect of using a high concentration acid and iron compound in combination is not clear, but when the amount of iron compound added exceeds 0.5% by weight, the expansion rate of the resulting expanded vermiculite decreases.
[0013]
Process 2
The mixture obtained in step 1 is kept at a temperature of 40 to 100 ° C., preferably 60 to 80 ° C. for a certain period of time, and then cooled to an ambient temperature of room temperature. As a specific example, the mixture is kept at 60 ° C. for about 12 hours and then cooled to room temperature.
In this step, any commonly used heating and cooling means can be used.
The heating effect in the process 2 is to promote the penetration of the added acid or iron compound into the entire vermiculite ore. Thus, it is considered that an exothermic reaction temperature of 90 ° C. or higher is achieved in the subsequent step 3, and the swelling time of the vermiculite raw stone is shortened.
[0014]
Process 3
Hydrogen peroxide solution is added to the mixed system cooled to ambient temperature.
The hydrogen peroxide solution may preferably be a commercially available about 1-35% aqueous solution, most preferably a 15% or higher aqueous solution. The amount of hydrogen peroxide added may vary depending on its concentration, the amount of acid used and the desired swelling rate. For example, the hydrogen peroxide solution is added so that hydrogen peroxide is in an amount of 2 mol to 5 mol with respect to 1000 g of the vermiculite ore, preferably 3 mol to 4 mol with respect to 1000 g of the original ore.
[0015]
After the addition of aqueous hydrogen peroxide, the mixture immediately undergoes an exothermic reaction and first rapidly rises to about 40 ° C. After gradually increasing the temperature to about 60 ° C., the temperature rapidly reaches 90 ° C. or higher and then gradually decreases. Such an exothermic reaction consists of a first reaction stage with hydrogen peroxide and an iron compound (˜about 40 ° C.), followed by a second reaction stage that occurs explosively between hydrogen peroxide and the raw vermiculite ( ~ 90 ° C or higher). During this time, the expansion of the vermiculite ore starts immediately after the addition of the hydrogen peroxide solution. When the exothermic temperature reaches 90 ° C. or more, most of the expansion occurs, and the desired expansion rate is reached.
[0016]
In the conventional method disclosed in Japanese Patent Publication No. 55-6600, etc., when hydrogen peroxide is allowed to act on vermiculite ore in the presence of acid, a slow exothermic reaction occurs, and the maximum heat is generated at about 45 ° C. The above temperature, especially 90 ° C. or higher could not be achieved. On the other hand, in the present invention, the combined use of the iron compound and the heating step 2 allows hydrogen peroxide to act on the raw vermiculite in the presence of a high concentration of acid, so that a temperature of 90 ° C. or higher can be achieved. Can be achieved.
Further, according to the conventional method, the temperature is slowly raised to about 45 ° C. which is the maximum temperature, for example, over about 20 minutes. However, in the present invention, the temperature reaches about 40 ° C. immediately after the addition of the hydrogen peroxide solution in Step 3. Furthermore, in the present invention, the time from the addition of hydrogen peroxide until the temperature of the mixture reaches 90 ° C. or higher is usually 1 minute to 5 minutes, particularly preferably 2 minutes to 4 minutes. And As a result, according to the present invention, the time until the expansion of the vermiculite ore reaches a desired expansion rate can be significantly reduced as compared with the conventional method.
[0017]
According to the present invention, the vermiculite ore is expanded about 10 times or more.
[0018]
Moreover, the pH of the expanded vermiculite obtained by the present invention is 3.5 or more, particularly 4 or more.
[0019]
The expanded vermiculite obtained by the method of the present invention is excellent in light weight and heat insulation, and further has high water retention, so that it is an industrial material, building material, heat insulation material, packing material, artificial soil molded product, etc. It is preferably used for molding.
[0020]
【Example】
Examples The vermiculite rough was expanded according to the method of the present invention as follows.
To 1.3 kg of vermiculite rough (particle size 3, approx. 5 mm square), first, 19.5 g of 98% concentrated sulfuric acid (1.5 wt% of the weight of vermiculite rough) and 2.6 g of iron compound (ferric sulfate, Vermiculite ore weight of 0.2% by weight) was added in order and mixed well using a ribbon blender. The mixed system was heated to about 60 ° C. using a hot air circulating dryer, kept at this temperature for 12 hours, and then cooled to room temperature.
Thereafter, 0.43 kg of 35 wt% aqueous hydrogen peroxide was added, and immediately after the addition, the temperature of the mixture was raised to about 45 ° C., and then slowly raised to about 60 ° C. Reached a temperature above ℃. As a result, about 4 minutes after the addition of the hydrogen peroxide solution, the temperature was raised to about 90 ° C., and the vermiculite ore expanded to 12 times. The pH of the obtained expanded vermiculite was 3.95.
[0021]
Comparative example As a comparative example, vermiculite was expanded according to the procedure described in Example 1 of JP-B-55-6600.
That is, 25 mL of 98% concentrated sulfuric acid was added to 500 g of rough vermiculite (particle size No. 3, approximately 5 mm square) and stirred well, and 100 mL of 35 wt% hydrogen peroxide was added thereto. Although swelled up to twice, the temperature of the mixture only increased to a maximum of 45 ° C. The pH of the obtained expanded vermiculite was 2.49.
[0022]
From the results of Examples and Comparative Examples, in the method of the present invention, the time required for the expansion of the vermiculite ore to reach the desired expansion rate is extremely fast compared to the known method, and the expanded vermiculite obtained thereby. It can be seen that the pH of the is higher.
[0023]
【The invention's effect】
According to the method of the present invention, by allowing hydrogen peroxide water to act in the presence of a high concentration of acid and iron compound, the swelling of vermiculite ore is not subjected to high-temperature rapid heating up to several hundred degrees C. This can be done by the heat generated by the process. In particular, the present invention is characterized in that the generated exothermic temperature reaches a maximum of about 90 ° C. or more, and the time required to reach a desired expansion rate is 5 minutes, so that the expansion time can be greatly shortened.
Furthermore, according to the method of the present invention, since the amount of high-concentration acid used can be reduced, expanded vermiculite having a pH of 3.5 or higher can be obtained.
[Brief description of the drawings]
FIG. 1 is a process flow diagram specifically illustrating the method of the present invention.

Claims (6)

To the vermiculite ore, 0.05 to 0.5 mol of concentrated sulfuric acid or concentrated hydrochloric acid with respect to 1000 g of the vermiculite ore and an iron compound in an amount of 0.1 to 0.5% by weight based on the weight of the vermiculite ore A method for producing expanded vermiculite, wherein the mixture is kept at a temperature of 40 to 100 ° C. for a certain period of time, cooled, and then expanded by adding hydrogen peroxide. The method for producing expanded vermiculite according to claim 1, wherein the iron compound is at least one selected from ferrous sulfate, ferric sulfate, ferrous chloride, and ferric chloride. The method for producing expanded vermiculite according to claim 1, wherein an exothermic reaction with a maximum temperature of 90 ° C. or more occurs by addition of hydrogen peroxide. The method for producing expanded vermiculite according to claim 1, wherein the temperature is raised to a temperature of 90 ° C or higher within 5 minutes after the addition of the hydrogen peroxide solution. The method for producing expanded vermiculite according to claim 1, wherein the pH of the expanded vermiculite is 3.5 or more. An expanded vermiculite for molding produced by the method according to claim 1.

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