JPH02277544A - Production of refractory hollow sphere - Google Patents

Abstract

PURPOSE:To obtain superior strength, shape and yield by coating the surface of a core material made of a combustible substance with a binder, sticking powdery refractory starting material to the core material, charging this core material and the residual powdery refractory starting material into a rotary granulator and shaping them while adding a binder. CONSTITUTION:The surface of a core material made of a combustible substance is coated with a binder and powdery refractory starting material is stuck to the core material. This core material and the residual powdery refractory starting material are charged into a rotary granulator with a rotating bottom plate and shaped while adding a binder. The resulting shaped core material is calcined to produce refractory hollow spheres. Since the coating layer on the surface of the core material is shaped and made dense, superior strength, shape and yield are obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to lightweight concrete, fireproof lightweight structural materials, buoyancy materials for offshore development, structural materials for flying objects, catalyst carriers, r-permeable materials, hydrogen (H2) gas This invention relates to improvements in the manufacturing method of fireproof hollow spheres used for adsorption/separation materials, oil-collecting and absorbing materials, sound-absorbing members for construction, composite materials, containers for laser fusion fuel, heat insulating materials for molten metal, etc.

[Prior art] The following methods have been used to manufacture hollow spheres: - After melting raw materials, they are flowed out of a furnace, and high-pressure gas is blown toward the flowed liquid to form the liquid into a hollow shape. A method of obtaining minute hollow spheres by scattering them as small spheres (melt spraying method); ■Using raw materials to which foaming material has been added or raw materials that originally contain moisture and volatile matter, and after aligning them to a certain level of precision, A method of obtaining micro hollow spheres with holes inside by firing and foaming the particles (thermal decomposition method); ■A material with a low melting point, such as a foamed polystyrene sphere, is coated with the desired raw material powder. .

After drying, this is fired to melt or decompose the core material to create voids inside, and then treated at high temperatures to sinter or melt the outer shell to generate a glass phase to obtain a hollow sphere. material decomposition method).

Among these methods, the core decomposition method is often used to produce hollow spheres.

As an example of a hollow sphere using this method, for example,
1-215238 discloses that a binder is applied to the surface of plastic particles, a refractory powder is attached to the surface of the particles by the binder to form a shell, and the plastic particles are removed by firing. 1 in the center
A method for producing a refractory insulation material is disclosed, which consists in obtaining hollow spheres of refractory material having several cavities.

In addition, Japanese Patent Application Laid-Open No. 62-230455 discloses that by specifying the shell thickness, air permeability, etc. of hollow granules for heat insulation, hollow granules can be used repeatedly over a long period of time as a material for shielding metal surfaces and as a heat insulator. This publication discloses an example of manufacturing a hollow spherical material by a core material decomposition method.

Furthermore, JP-A No. 63-149306 discloses a hollow sphere or a hollow sphere composite in which the strength of the wall is increased by applying another layer to the surface of metalized lightweight spherical particles whose core portion is made of a foamed polymer. In the manufacturing method, metallized lightweight granular particles with a metal wall thickness of 5 to 20 μm are treated and coated with a fine dispersion of any one of metals, metal oxides, ceramic materials, and refractories to form a coating layer. The lightweight spherical particles having a thickness of 15 to 500 μm are dried, the dried particles are heated to a temperature of about 400° C. to thermally decompose the polymer core, and then
A method is disclosed, characterized in that the sintering is carried out at a temperature of 14oO<0>C.

[Problems to be Solved by the Invention] The most important point in solving the problems in manufacturing hollow spheres by the core decomposition method as described above lies in the granulation process. That is, how well the outside of the core material is coated with the raw material powder to form a coarse ball with high sphericity.

For this purpose, factors such as the particle size of the raw material powder, selection and blending ratio of a binder suitable for the raw material, type of granulator, granulation conditions, and drying method after granulation must be sufficiently controlled.

However, the hollow spheres produced by the above-mentioned core material decomposition method all have problems in strength, are not perfectly spherical, have a large angle of repose, have poor fluidity, and furthermore have poor yields and high costs. There are issues such as:

Therefore, an object of the present invention is to provide a method for producing a fireproof hollow sphere using an improved core decomposition method that can easily solve the above-mentioned problems.

[Means for Solving the Problems] That is, the present invention uses a combustible material as a core material, coats the surface of the core material with refractory powder, and then heats the coated core material to thermally decompose it to form a hollow material. In the method for producing a refractory hollow sphere by a core material decomposition method, the method comprises: (a) coating the surface of the core material of a flammable substance with a binder; and (b) applying refractory raw material powder to the core material obtained in step (a). (c) The core material obtained in step (b) and the remaining refractory raw material powder are charged into a bottom plate rotary granulator and shaped while adding a binder. Relating to the manufacturing method.

[Function] The core material of the combustible substance used in the method of the present invention can be any material used in a normal core material decomposition method, such as expanded polystyrene rings, organic fiber spheres, Although solid polyethylene rings etc. can be used,
From a cost perspective, it is preferable to use a styrofoam ring.The spherical diameter of the core material is preferably within the range of 1 to 10I.6 The spherical diameter is 1! If it is less than III or exceeds 10 mm, it is not preferable because the refractory raw material powder cannot be coated in a suitable state.

As the refractory powder raw material used in the method of the present invention, any material used in conventional refractory hollow spheres can be used, such as zirconia, magnesia, alumina, silica, silicon carbide, chamotte, etc. can be used. Note that the particle size of all refractory raw material powders is 0.
It is necessary that particles of 3 mm or less and 74 μm or less of particles be contained at least 30%. Particle size of refractory raw material powder is 0
．． If it exceeds 3mm+, the core material cannot be coated with the refractory raw material powder, and if the proportion of particles of 74 μm or less is less than 30%, the refractory raw material powder will not be coated properly during shaping in step (c). This is not preferred because peeling of the powder coating may occur.

A few examples of the composition of the refractory raw material powder are as follows: When producing magnesia-based refractory hollow spheres, for example, it contains 80 parts by weight or more of magnesia, and the balance is alumina cement, chamotte, clays, calcia, and magnesium carbonate. A refractory raw material powder containing one or more selected from the group consisting of , calcium carbonate, silica, alumina, etc. can be used.

Furthermore, when producing cordierite or zirconia refractory hollow spheres, a refractory raw material powder having a composition in which magnesia is replaced with cordierite or zirconia is used. be able to.

In step (a) of the method of the present invention, when expanded polystyrene is used as the core material, the binder coated on the surface of the core material of the combustible material is preferably an aqueous polyvinyl alcohol solution from the viewpoint of wettability with the expanded polystyrene material. be. It is not preferable to use a product dissolved in an organic solvent from the viewpoint of working environment, danger, etc. The viscosity of the polyvinyl alcohol aqueous solution is preferably within the range of 104 to 102 voids.

If the viscosity of the polyvinyl alcohol aqueous solution exceeds 104 voids, the aqueous solution will not adhere uniformly to the surface of the core material and will form a lump, which is undesirable.
If the number of voids is less than 2, the amount of the refractory raw material powder deposited in step (b) will decrease, the shell thickness of the refractory raw material powder will become thinner, and the strength will also decrease, which is not preferable.

The binder used in step (c) of the method of the present invention can be a water-soluble organic binder or an inorganic binder. Examples of the water-soluble organic binder include methylcellulose, carboxymethylcellulose, polyvinyl alcohol, molasses, and ligninsulfonic acid. Further, as the inorganic binder, colloidal silica, colloidal alumina, amine silicate, water glass, etc. can be used. The viscosity of the binder used must be within the range of 1000 to 5 centivoise. If the viscosity of the binder exceeds 1000 centimeters, the balls tend to stick to each other during shaping in step (C), making it difficult to obtain pearls. This is not preferable because the refractory raw material powder layer may peel off during shaping.

Hereinafter, the method of the present invention will be explained step by step.

First, in step (a), a core material of a flammable substance and a binder are charged into a known mixer such as a mortar mixer, a high speed mixer, a Henschel mixer, etc., and kneaded to coat the surface of the core material with the binder.

Next, in step (b), the core material obtained in step (a) is charged into a separate mixer such as a mortar mixer, high-speed mixer, Henschel mixer, etc., together with the refractory raw material powder having a predetermined composition, and kneaded. This causes the refractory raw material powder to adhere to the surface of the core material.

Furthermore, in step (c), the core material coated with the refractory raw material powder obtained in step (b) and the refractory raw material powder left over in step (b) are charged into a granulator having granulation performance, and rotated. While granulating, the binder is gradually added at a rate of 10 to 100 cc/sec), and the excess refractory raw material powder is shaped while adhering. The coating layer is shaped and becomes dense by the treatment in step (c). As the granulator used in step (c), for example, a bottom plate rotary granulator can be used, and as the bottom plate rotary granulator, for example, a Marmerizer can be used.
[Manufactured by Fuji Paudal Co., Ltd.] etc. are preferably used.

The shaped core material obtained in step (c) is then subjected to 5 steps according to a conventional method.
After drying at 0 to 80°C for 12 to 24 hours, a fireproof hollow sphere can be obtained by firing at a temperature of about 1000 to 1800°C in a furnace such as a rotary kiln.

The hollow spheres obtained according to the above operation have improved strength, shape, yield, etc., and can be used, for example, in lightweight concrete, fire-resistant lightweight structural materials, buoyancy materials for marine development, structural materials for flying objects, catalyst carriers, permeable materials, and hydrogen. (H2) It can be suitably used as a gas adsorption/separation material, an oil collecting material, a sound absorbing member for construction, a composite material, a container for laser fusion fuel, a heat insulating material for molten metal, etc.

In addition, when the core material of the combustible substance is 100 parts by weight, the amount of binder added in step (a) is 100 to 1000 parts by weight.
The amount of refractory raw material powder added in step (b) is within the range of 100 to 10,000 parts by weight, and the amount of binder added in step ((+) is 10 to 7 parts by weight.
00 parts by weight.

[Example] Hereinafter, the method for producing a refractory hollow sphere according to the method of the present invention will be further explained with reference to Examples.

E1 ■ Yumagnesia refractory hollow sphere 100 parts by weight of expanded polystyrene spheres with a diameter of 31 mm and a 15% aqueous solution of polyvinyl alcohol (viscosity: 10'voices) 300 parts by weight
Parts by weight were charged into a mortar mixer and kneaded to coat expanded polystyrene spheres with an aqueous polyvinyl alcohol solution.

Next, the obtained expanded polystyrene spheres, 85 parts by weight of magnesia containing 50% or more of particles with a particle size of 0.31 or less and 74 μm or less, and 10 parts of alumina cement (0.3 m or less) were added.
Refractory raw material powder 2 consisting of parts by weight and 5 parts by weight of bentonite
500 parts by weight were charged into another mortar mixer and kneaded to adhere the refractory raw material powder to the expanded polystyrene balls.

Next, the foamed polystyrene balls with refractory raw material powder attached and the refractory raw material powder left over from the above step are charged into a marmerizer, and 400 parts by weight of a 1% aqueous solution of polyvinyl alcohol (viscosity 100 centivoise) is added (at a rate of 20 cc/cm). )
Refractory raw material powder was applied and shaping was performed.

The obtained spheres were dried at 70°C for 10 hours, and then fired in a rotary kiln at 1400°C for 4 hours to obtain magnesia refractory hollow spheres.

The properties of the obtained magnesia refractory hollow spheres are determined by the following first method.
Record in the table.

11fi Yukogelite fireproof hollow sphere 100 parts by weight of expanded polystyrene spheres with three diameter wheels and a 10% aqueous solution of polyvinyl alcohol (viscosity: 102 voids) 28
0 parts by weight were charged into a mortar mixer and mixed to coat expanded polystyrene balls with an aqueous polyvinyl alcohol solution.

Next, the obtained expanded polystyrene spheres and 4000 parts by weight of a refractory raw material powder consisting of 90 parts by weight of cordierite and 10 parts by weight of kaolin containing 70% or more of particles having a particle size of 0.3- or less and 74 μ- or less were separated into The refractory raw material powder was attached to the expanded polystyrene balls by charging the balls into a mortar mixer and kneading them.

Next, the foamed polystyrene spheres with refractory raw material powder attached and the refractory raw material powder left over from the above step were charged into a marmerizer, and 300 parts by weight of a 3% aqueous solution of carboxymethyl cellulose (viscosity: 150 centiboise) was added (80 cc/sec). refractory raw material powder was deposited and shaped.

The obtained spheres were dried at 60°C for 8 hours, and then fired in a rotary kiln at 1380°C for 4 hours to obtain cordierite refractory hollow spheres.

The properties of the cordierite refractory hollow spheres obtained are listed in Table 1 below.

Futane ■ Yuzirconia fireproof hollow sphere 100 parts by weight of expanded polystyrene spheres with a diameter of 3 and a 15% aqueous solution of volivinyl alcohol (viscosity: 103 voids) 30
0 parts by weight was charged into a mortar mixer and kneaded to coat expanded polystyrene balls with an aqueous polyvinyl alcohol solution.

Next, the obtained expanded polystyrene spheres and 4000 parts by weight of a refractory raw material powder made of Mg○ stabilized zirconia (Zr○296:Mg04) containing 90% or more of particles with a particle size of 0.3 mm or less and 74 μm or less were separated into The refractory raw material powder was attached to the expanded polystyrene balls by charging the balls into a mortar mixer and kneading them.

Next, the styrofoam balls with refractory raw material powder attached and the refractory raw material powder left over from the above step were charged into a marmerizer, and while adding 450 parts by weight of a 1% aqueous solution of polyvinyl alcohol (viscosity: 100 centivoise) (at a rate of 90 cc/sec), refractory raw material powder was deposited and shaped.

The obtained spheres were dried at 70°C for 10 hours, and then fired in a rotary kiln at 1800°C for 5 hours to obtain zirconia refractory hollow spheres.

The properties of the obtained zirconia refractory hollow spheres are as follows:
Record in the table.

In Examples 1 to 3 described above, magnesia hollow spheres (comparison Product 1), cordierite hollow spheres (comparative product 2), and zirconia hollow spheres (comparative product 3) were obtained.

The characteristics of Comparative Products 1 to 3 are also listed in Table 1.

[Effects of the Invention] As is clear from the above-mentioned Examples, refractory hollow spheres having excellent strength, shape, and yield can be obtained by the method of the present invention, which is a relatively simple operation.

Patent applicant Shinagawa White Brick Co., Ltd.

Claims (4)

[Claims] 1. Manufacture of fire-resistant hollow spheres by a core material decomposition method, which consists of using a flammable substance as a core material, coating the surface of the core material with refractory powder, and then heating the coated core material to thermally decompose it and make it hollow. In the method, (a) a binder is coated on the surface of a core material of a combustible substance, (b) a refractory raw material powder is attached to the core material obtained in step (a), and (c) a refractory raw material powder is applied to the core material obtained in step (b). The core material and the remaining refractory raw material powder are charged into a bottom plate rotary granulator.
A method for producing a fire-resistant hollow sphere, characterized by shaping it while adding a binder. 2. The refractory raw material powder contains 80 parts by weight or more of magnesia,
2. The method for producing a refractory hollow sphere according to claim 1, wherein the remainder is one or more components selected from the group consisting of alumina cement, chamotte, clays, calcia, magnesium carbonate, calcium carbonate, silica, and alumina. 3. The refractory raw material powder contains 80 parts by weight or more of cordierite, and the remainder is one or more components selected from the group consisting of alumina cement, chamotte, clays, calcia, magnesium carbonate, calcium carbonate, silica, and alumina. A method for manufacturing a fireproof hollow sphere according to claim 1. 4. The refractory raw material powder contains 80 parts by weight or more of zirconia,
2. The method for producing a refractory hollow sphere according to claim 1, wherein the remainder is one or more components selected from the group consisting of alumina cement, chamotte, clays, calcia, magnesium carbonate, calcium carbonate, silica, and alumina.