JP2007320805A - Hard foamed pearlite and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently and stably manufacturing hard foamed pearlite being fine, spherical and highly strong where non-granulated rock grains are used as a raw material and to provide the hard pearlite. <P>SOLUTION: Rhyolitic non-granulated rock grains having an average grain diameter of 5 mm or less and a moisture content of 6 wt.% or less, favorably 3 wt.% or less, are used as the raw material. Different baking processes corresponding to the average grain diameter and the moisture content of the rock grains are performed. Specifically, the hard foamed pearlite having an average grain diameter of 5 mm or less, a sphericity of 0.7 or more and a compressive strength of 25 N/mm<SP>2</SP>or more is manufactured by one-stage combustion for raw material rock grains having an average grain diameter of 0.6-5 mm and by two-stage combustion for raw material rock grains having an average grain diameter of 50 μm-0.6 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a fine high-strength spherical hard foam pearlite and a method for producing the same. More specifically, the present invention relates to a hard foam pearlite having higher strength and higher sphericity than conventional products and a method for producing the same.

Fine, high-strength foams are desired as light weight extenders for paints, resins, and building materials. At present, pearlite, shirasu foam, and the like are often used as light weight extenders. Perlite used as a lightweight foam is made by crushing vitreous rhyolites such as nacre, obsidian, and pine sebite, and firing and firing them at high temperatures. The volcanic ejecta containing is foamed by high-temperature treatment. However, many conventional perlite and shirasu foams have low strength or deformed shapes.

For example, in conventional foamed pearlite, the compressive strength (hydrostatic pressure) of a nearly spherical shape is approximately 10 N / mm ² or less, and the high strength one is distorted in shape and far from a spherical shape. The compressive strength of a commercially available shirasu foam is, for example, about 80 to 100 kg / cm ² (hydrostatic pressure).

On the other hand, a fly ash balloon (hereinafter referred to as FAB) is known as a spherical and high-strength lightweight body. However, FAB is a byproduct obtained by separating and recovering a very small amount of foam contained in ash generated during coal combustion such as power generation, and there is a problem that the quantity is small and the particle size cannot be controlled.

Conventionally, as a method for producing foamed pearlite, a production method in which pearlite particles adjusted in particle size are preheated at 100 to 400 ° C. and then fired and fired in three stages is known (Patent Document 1). However, the foamed pearlite obtained by this production method has a residual rate of approximately 40% or less under a compressive strength of 20 kg / cm ² and is low in strength. In addition, a production method is known in which natural glassy rock particles such as pearlite are preheated at 600 to 900 ° C. and then foamed and heated at 900 to 1000 ° C. (Patent Document 2). Although this method is intended to increase the expansion ratio by preheating, it does not control the firing temperature according to the particle size and water content of the raw material powder, so the strength of the foam produced Is low.

Further, a method for producing a lightweight foam body is known in which a granulated product having components adjusted is used, and after the foaming by main firing, a glassy layer (melted sintered layer) is formed on the surface by finish firing (Patent Document 3). ). According to this production method, a foam having a crushing strength of 800 to 1100 N can be obtained, but this is a method using a granulated material having a diameter of 5 to 15 mm as a raw material, and not using a non-granulated material as a raw material. Moreover, it differs from the method of manufacturing a fine foam of 5 mm or less.
Japanese Patent Application Laid-Open No. 07-277851 JP 58-099128 A Japanese Patent Application No. 2001-19504

The present invention solves the above-mentioned problems in the conventional foamed lightweight body and its production method, and a production method for efficiently and stably producing fine spherical high-strength hard foamed pearlite using non-granulated rock grains as a raw material, and The hard perlite is provided.

The present invention relates to a fine high-strength spherical hard foam pearlite and a method for producing the same, which have solved the above-described problems with the following configuration.
(1) A foam made from rhyolite non-granulated rock particles, characterized by an average particle size of 5 mm or less, a sphericity of 0.7 or more, and a compressive strength of 25 N / mm ² or more. Hard foam perlite.
(2) A method of producing foamed hard pearlite by firing one stage of rhyolite non-granulated rock grains having an average particle size of 0.6 mm to 5 mm and a water content of 6 wt% or less. A method for producing a hard foam pearlite, comprising firing in the following temperature range according to the compressive strength.
(B) In the case of compressive strength ^{25N / mm 2 ~40N / mm 2} : firing temperature 970 ℃ ~1030 ℃
(B) if the compression strength ^{40N / mm 2 ~55N / mm 2} : firing temperature 950 ℃ ~1010 ℃
(C) When the compressive strength is 55 N / mm ² or more: firing temperature 900 ° C. to 970 ° C.
(3) A method for producing foamed hard pearlite by pre-firing and main-firing two-stage firing of rhyolite-like non-granulated rock grains, having an average particle diameter of 0.1 mm or less and a water content of 3 to 6 wt. % Rock grains, or rock grains having an average particle size of 50 μm to 0.6 mm and a water content of 3% or less, the main firing temperature T ₁ is 900 ° C. to 1000 ° C., and the temporary firing temperature T ₀ is A method for producing hard foamed pearlite, which is a temperature [T ₀ = T ₁ − (20 to 200 ° C.)] lower than the main firing temperature T ₁ by 50 ° C. to 200 ° C.
(4) The method for producing rigid foamed pearlite in the production method of (3), wherein the two-stage firing is performed in the temperature range shown below according to the compressive strength of the foamed perlite after firing.
(D) For compressive strength of 25 N / mm ^{2 to} 40 N / mm ² : primary firing temperature 900 ° C. to 800 ° C., secondary firing temperature 970 ° C. to 1020 ° C.
(E) if the compression strength ^{40N / mm 2 ~55N / mm 2} : primary firing temperature 850 ° C. to 950 ° C., the secondary firing temperature 950 ℃ ~1010 ℃
(F) When the compressive strength is 55 N / mm ² or more: primary firing temperature 850 ° C. to 970 ° C., secondary firing temperature 970 ° C. to 1020 ° C.

The hard foamed pearlite of the present invention is a fine foam having an average particle size of 5 mm or less made of rhyolite-like non-granulated rock grains, has a spherical shape with a sphericity of 0.7 or more, and a compressive strength of 25 N. Since it is a high-strength lightweight body of / mm ² or more, it is suitable as a lightweight extender such as paints, resins, and building materials, and can be widely used as a lightweight material in a wide range of applications including the above fields.

The production method of the present invention uses rhyolitic non-granulated rock grains as a raw material, and increases the sphericity and strength by controlling the firing process according to the average particle diameter and water content of the raw rock grains. According to the manufacturing method of the present invention, it is possible to manufacture a hard foam pearlite having the above sphericity and compressive strength.

The present invention will be specifically described below.
In the present invention, rhyolitic non-granulated rock grains having an average particle diameter of 5 mm or less and a water content of 6 wt% or less are used as raw materials, and the firing process is controlled according to the average particle diameter and water content of the raw rock grains. Thus, a hard foam pearlite with improved sphericity and strength is provided. Specifically, it is a fine foam having an average particle size of 5 mm or less, and has a spherical shape with a sphericity of 0.7 or more. In addition, a high-strength hard foam pearlite having a compressive strength of 25 N / mm ² or more is provided.

The hard foam pearlite of the present invention uses rhyolite non-granulated rock grains as a raw material. Since a granulated material is not used as a raw material, a granulation step is unnecessary, and the particle size may be adjusted by sieving the crushed rhyolite rock particles. Rhyolite rocks are rocks containing vitreous components such as pearlite, obsidian, and pine stone, and contain structural water according to the rock type.

Rhyolite non-granulated rock grains used as a raw material in the present invention have an average particle diameter of 5 mm or less and a water content of 6 wt% or less, preferably a water content of 3% or less. When the average particle size exceeds 5 mm, the foam is distorted due to cracks inside the particles, and it is difficult to form a spherical shape. On the other hand, if the water content is more than 6 wt%, excessive foaming causes a decrease in strength and distortion of the shape, making it difficult to obtain a spherical foam having a high sphericity.

In general, obsidian has a water content of 2 wt% or less, and obsidian is basically suitable as a raw material. Further, since the water content of nacre is generally 3 to 6 wt%, nacre can also be used as a raw material. Malecanite having an intermediate structure between obsidian and pearlite can also be used as a raw material. On the other hand, since the water content of pine sebum is approximately 4 to 10 wt%, it is preferable to use a material having a low water content.

The production method of the present invention varied depending on the average particle size and water content of rhyolite non-granulated rock particles having an average particle size of 5 mm or less and a water content of 6 wt% or less, preferably 3 wt% or less. Perform the firing process. Specifically, one-stage firing is performed on raw rock particles having an average particle diameter of 0.6 mm to 5 mm, and two-stage firing is performed on raw rock grains having an average particle diameter of 50 μm to 0.6 mm.

In the case of using raw material rock grains having an average particle diameter of 0.6 mm to 5 mm as a raw material, it is preferable to perform the firing in the following temperature range according to each stage of the compressive strength of the foamed pearlite. In each case, it is difficult to obtain foamed pearlite having the desired compressive strength if it is outside the firing temperature range shown below. The firing time is suitably 5 to 10 minutes.

(B) In the case of compressive strength ^{25N / mm 2 ~40N / mm 2} : firing temperature 970 ℃ ~1030 ℃
(B) if the compression strength ^{40N / mm 2 ~55N / mm 2} :, firing temperature 950 ℃ ~1010 ℃
(C) When the compressive strength is 55 N / mm ² or more: firing temperature 900 ° C. to 970 ° C.

In the one-stage firing, it is preferable that the firing temperature is greatly lowered within the above firing temperature ranges as the particle size of the raw material rock grains increases. For example, when producing foamed pearlite with a compressive strength of 25 N / mm ^{2 to} 40 N / mm ² [above (1)], the closer the average particle diameter of the raw rock particles is to 5 mm, the closer the firing temperature is to 970 ° C., On the other hand, the closer the average particle size of the raw rock particles is to 0.6 mm, the closer the firing temperature is to 1030 ° C. The same applies to the cases (2) and (3).

For rock particles having an average particle size of 50 μm to 0.6 mm as a raw material, rock particles having an average particle size according to the water content are used. Specifically, when the water content is 3 wt% or less, rock grains having an average particle size of 50 μm to 0.6 mm can be used, and a hard foam having high compressive strength and high sphericity by applying the following firing process. Perlite can be obtained. On the other hand, when the water content is 3 to 6 wt%, rock grains having an average particle diameter of 0.1 mm or less are used. When the water content is 3 to 6% by weight, the use of rock grains having an average particle size of more than 0.1 mm makes the shape distorted, making it difficult to obtain hard foamed pearlite having a high sphericity.

In the above-described two-stage firing, the main firing temperature T ₁ is 900 ° C. to 1000 ° C., and the temporary firing temperature T ₀ is a temperature T ₀ = T ₁ − (20 to 20 ° C.) lower than the main firing temperature T _1. 200 ° C.). In the conventional manufacturing method, even if the firing temperature of the two-stage firing is determined in stages, the firing temperature at each stage includes an overlapping range. For example, when performing continuous firing, provisional firing and main firing are performed. However, there is a problem in that the firing process cannot be sufficiently controlled.

The time for the second firing is suitably 5 to 10 minutes for primary firing and 7 to 10 minutes for secondary firing. In addition, this two-stage baking may be a method in which the temperature is lowered and cooled after the first stage baking and then heated again to perform the second stage baking, or the first stage baking is performed without providing an intermediate cooling step. Continuous firing may be performed in which the temperature is further increased and the second-stage firing is performed later.

In the two-stage firing method of the present invention, the firing process can be sufficiently controlled by performing the preliminary firing at the temporary firing temperature T ₀ with a predetermined temperature difference based on the specific main firing temperature T _1. . When the main firing temperature T ₁ is lower than 900 ° C., a sufficient foaming state is not achieved, and when it is higher than 1000 ° C., excessive foaming is likely to occur.

Also in the two-stage firing method of the present invention, firing is preferably performed in a firing temperature range corresponding to each stage of the compressive strength of the foamed pearlite. Specifically, the two-stage baking is preferably performed in the following temperature range. In each case, it is difficult to obtain foamed pearlite having the desired compressive strength if it is outside the firing temperature range shown below.

(D) For compressive strength of 25 N / mm ^{2 to} 40 N / mm ² : primary firing temperature 900 ° C. to 800 ° C., secondary firing temperature 970 ° C. to 1020 ° C.
(E) if the compression strength ^{40N / mm 2 ~55N / mm 2} : primary firing temperature 850 ° C. to 950 ° C., the secondary firing temperature 950 ℃ ~1010 ℃
(F) When the compressive strength is 55 N / mm ² or more: primary firing temperature 850 ° C. to 970 ° C., secondary firing temperature 970 ° C. to 1020 ° C.

After the one-stage baking or the two-stage baking, the unfoamed material and the like are removed from the fired foam by a selection means such as water selection, sieving, airflow classification, and the desired high-strength spherical lightweight foam perlite is obtained.

According to the production method of the present invention, hard foam pearlite having an average particle size of 5 mm or less, a sphericity of 0.7 or more, and a compressive strength of 25 N / mm ² or more can be produced stably and efficiently. The sphericity is represented by a ratio (BD / MD) of the maximum diameter MD of a circular projection obtained by projecting a sphere onto a plane and the diameter BD orthogonal to the maximum diameter MD (BD / MD). Close to. The compressive strength is a pressure at which 40 wt% remains without being crushed by applying hydrostatic pressure by immersing foamed pearlite in water.

Examples of the present invention are shown below together with comparative examples.
[Example A]
Obsidian having a water content of 2 wt% or less was used, the rock grain was adjusted to the particle size shown in Table 1, and fired at the temperature shown in Table 1 to obtain foamed perlite. Table 1 shows the physical properties of the foamed perlite produced.

As shown in Table 1, each of the foamed pearlites of Examples 1 to 16 produced under the conditions of the present invention has a compressive strength (pressure at 40 wt% remaining by hydrostatic pressure method) of 35 N / mm ² or more. The sphericity is 0.7 or more, preferably 7.5 or more, and more preferably 0.8 or more. On the other hand, all of the foamed pearlite of Comparative Examples 21 to 25 outside the production conditions of the present invention has a compressive strength of 10 N / mm ² or less, and the foamed pearlite of Comparative Example 26 has a distorted shape with high compressive strength, I can't get a spherical one.

[Example B]
Pearlite with a water content of 3 to 6 wt% was used, the rock grains were adjusted to the particle size shown in Table 2, and fired at the temperature shown in Table 2 to obtain foamed perlite. The physical properties of the foamed perlite produced are shown in Table 2. As is apparent from this result, when the grain size of the raw material rock particles is larger than 0.1 mm, the foam is deformed in two stages, and even if the firing temperature is lowered, the shape of the foam cannot be obtained as a distorted spherical foam. On the other hand, those made from rock grains having an average particle size of 0.1 mm or less are spherical foams having a sphericity of 0.7 or more and a compressive strength of 30 N / mm ² or more.

Claims (4)

A hard foam made from rhyolite non-granulated rock grains, having an average particle size of 5 mm or less, a sphericity of 0.7 or more, and a compressive strength of 25 N / mm ² or more. Perlite.
A method for producing foamed hard pearlite by firing one stage of rhyolite non-granulated rock grains having an average particle size of 0.6 mm to 5 mm and a water content of 3 wt% or less. Accordingly, a method for producing hard foamed pearlite, characterized by firing in the following temperature range.
(B) In the case of compressive strength ^{25N / mm 2 ~40N / mm 2} : firing temperature 970 ℃ ~1030 ℃
(Ii) if the compression strength ^{40N / mm 2 ~55N / mm 2} : firing temperature 950 ℃ ~1010 ℃
(C) When the compressive strength is 55 N / mm ² or more: firing temperature 900 ° C. to 970 ° C.
This is a method for producing foamed hard pearlite by pre-firing and main-firing two-stage firing of rhyolite non-granulated rock grains, with an average particle diameter of 0.1 mm or less and a water content of 3-6 wt% Or a rock grain having an average particle size of 50 μm to 0.6 mm and a water content of 3% or less, the main firing temperature T ₁ is 900 ° C. to 1000 ° C., and the temporary firing temperature T ₀ is the main firing temperature. A method for producing hard foamed pearlite, which is a temperature [T ₀ = T ₁ − (20 to 200 ° C.)] lower than T ₁ by 50 ° C. to 200 ° C.
The manufacturing method of Claim 3 WHEREIN: The manufacturing method of the hard foam pearlite which performs two-stage baking in the temperature range shown below according to the compressive strength of the foamed pearlite after baking.
(D) For compressive strength of 25 N / mm ^{2 to} 40 N / mm ² : primary firing temperature 900 ° C. to 800 ° C., secondary firing temperature 970 ° C. to 1020 ° C.
(E) if the compression strength ^{40N / mm 2 ~55N / mm 2} : primary firing temperature 850 ° C. to 950 ° C., the secondary firing temperature 950 ℃ ~1010 ℃
(F) When the compressive strength is 55 N / mm ² or more: primary firing temperature 850 ° C. to 970 ° C., secondary firing temperature 970 ° C. to 1020 ° C.