JPH0873232A - Production of fine hollow glass spherical body - Google Patents

Abstract

PURPOSE: To efficiently produce a fine hollow glass spherical body high in strength and excellent in whiteness. CONSTITUTION: A volcanic vitreous deposite powder having <=20μm grain size is supplied to a dispersion part filled with a glass solid sphere and silica sand, and a pulsating air having positive pressure is supplied to disperse the powder from its under part so that an upflow flow rate at the dispersion part may be 10-100cm/sec, and transported to a vertical foaming area maintained at 900-1100 deg.C to be foamed hollow body is recovered from a foamed product by gravity classification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing fine hollow glass spheres using a volcanic glassy deposit as a raw material. More specifically, the present invention relates to a method for efficiently producing a fine hollow glass sphere having high strength and excellent whiteness.

[0002]

2. Description of the Related Art Fine hollow glass spheres have a small specific gravity and are excellent in heat resistance, and have attracted attention as lightweight fillers for various metals, ceramics, concrete, plastics, etc. It has increased.

Heretofore, as a method for producing fine hollow glass spheres using a volcanic glassy deposit as a raw material, fine particles of Shirasu are fired at a temperature of 800 to 1200 ° C. for 10 seconds to 10 minutes and then in water. A method for producing a fine hollow glass sphere by separating specific gravity or air classification is known (Japanese Patent Publication No. 48-17645). However, in this method, it is difficult to obtain a desired fine hollow glass sphere even if a volcanic glassy deposit having a particle size of 20 μm or less is treated.

On the other hand, as a pretreatment of raw materials, a method for producing ultrafine hollow glass spheres by heating with an acid solution is disclosed (Japanese Patent Publication No. 2967/1992).
No. 50). However, in this method, since the raw material is in the form of fine particles, the particles agglomerate in the conventional heat-foaming device, and uniform heat-foaming is difficult and the hollow glass spheres cannot be obtained efficiently.

[0005]

Under these circumstances, the present invention uses a volcanic vitreous deposit as a raw material to produce a fine hollow glass sphere having high strength and excellent whiteness, which is formed into particles when heated and foamed. The purpose of the present invention is to provide a method for producing efficiently without causing aggregation.

[0006]

Means for Solving the Problems As a result of intensive studies on the method for producing fine hollow glass spheres using a volcanic glassy deposit as a raw material, the present inventors have found that the volcanic glassy deposit powder having a particle size of 20 μm or less. The body is supplied to the dispersion part of a specific structure, and air pulsation is given from the lower part to disperse the powder,
By transporting to a foaming region that maintains a specific temperature with the flow of air, it was found that homogeneous foaming is performed, and it is possible to efficiently obtain fine hollow glass spheres, and the present invention was completed based on this finding. It was

That is, according to the present invention, a volcanic glassy sediment powder having a particle size of 20 μm or less is supplied to a dispersion part formed by filling a glass solid sphere and silica sand on the upper part of a perforated plate. Thus, the pressure at the lower part of the dispersion part is positive, and the pulsating air has a rising flow velocity of 10 to 100 cm /
The powder is dispersed so as to be supplied in seconds, the powder is dispersed, transported to a vertical foaming zone holding a temperature of 900 to 1100 ° C., and foamed. To provide a method for producing a fine hollow glass sphere.

In the method of the present invention, the volcanic glassy deposit used as a raw material is a naturally occurring mineral such as shirasu, obsidian, pearlite and pinelite, and these are usually SiO ₂ , Al ₂ O ₃ and Fe. ₂ O ₃ , CaO, MgO, Na ₂
It is composed of O and K ₂ O and contains 3 to 10% by weight of water.

In the method of the present invention, these volcanic glassy deposits are pulverized, and the pulverized products are classified by dry classification, wet classification, or the like into particles having a particle size of 20 μm or less.

In the method of the present invention, this particle size is 20 μm.
The following volcanic glassy deposit powder may be foamed as it is, but in order to obtain hollow glass spheres with higher whiteness, hydrochloric acid of about 0.3 to 3 N is added to the powder, and
It is preferable to remove iron by hydrothermal treatment at a temperature of 0 to 200 ° C and a steam pressure of 0.5 to 1.5 MPa. In this case, the amount of the hydrochloric acid aqueous solution used was 1 g of powder.
A range of 1 to 1.5 ml is suitable. This hydrothermal treatment is desirably performed for at least 8 hours, and within this time, the iron content cannot be sufficiently removed.

Next, the hydrothermally treated powder of the volcanic vitreous deposit having a particle size of 20 μm or less is supplied to a dispersion portion formed by filling the upper part of the perforated plate with glass solid spheres and silica sand. To do. As the solid glass sphere, usually 1 to 3 m
The particle size is about m, and the particle size of silica sand is usually about 100 to 300 μm. The use ratio of the glass solid sphere and silica sand is usually selected in the range of 1:10 to 1: 1 by weight.

By supplying pulsating air having a positive pressure in the lower part of the dispersion part from the lower part of the dispersion part, the volcanic glassy sediment powder is dispersed. At this time, the pulsation rate of air is preferably in the range of 10 to 50 times / second. In addition, the amount of air supplied is such that the upflow velocity of the air in the dispersion section is 10 to 10.
Adjust to 100 cm / sec.

The thus dispersed volcanic glassy sediment powder is conveyed by a flow of air to a vertical foaming zone which maintains a temperature of 900 to 1100 ° C., and is foamed by heating. The structure of the foaming zone is preferably a bundle of three or more vertical cylinders per 100 cm ² in cross-sectional area, whereby uniform heating and foaming is performed.

Further, from the upper part of the foamed region, the foamed region cross section 100
It is preferable to introduce 10 liters / minute or more of air per cm ² , whereby the heated air and the foam can be cooled, and the condensation of water in the foam recovery section can be suppressed.

In the present invention, the hollow body is recovered by subjecting the heat-foamed material to a specific gravity difference, for example, by separating it into water by floating sedimentation or air classification.

According to such a method, the particle size is 30 μm.
The following fine hollow glass spheres can be obtained at a high recovery rate of 50% or more based on the weight of the raw material. The fine hollow glass spheres thus obtained have a higher strength and an excellent whiteness as compared with those obtained by the conventional apparatus.

[0017]

EFFECTS OF THE INVENTION According to the present invention, the volcanic glassy deposit fine powder, which cannot be obtained by the conventional apparatus for homogeneous foaming by heating and cannot obtain a high-quality hollow body, has high strength and excellent whiteness. It is possible to efficiently produce fine hollow glass spheres.

The fine hollow glass spheres obtained by the method of the present invention are useful as a lightweight filler for various metals, ceramics, concrete, plastics and the like.

[0019]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A volcanic glassy deposit having a composition shown in Table 1 (produced in Iizaka-machi, Fukushima City, Fukushima Prefecture, commonly known as Fukushima Shirato) was crushed to prepare a powder raw material.

[0021]

[Table 1]

As the liquid medium, water glass (JIS 3
No.) Using a 0.2% by weight aqueous solution, the above-mentioned powdery raw material was charged, and classified by elutriation using a difference in the sedimentation speed of particles in water at separation particle sizes of 5 μm and 10 μm. The proportion of particles having a particle diameter of more than 10 μm contained in the classified particles was 10% by weight or less in any case, and the proportion of particles having a particle diameter of less than 5 μm was 10% by weight or less in any case.

Next, the classified powder is mixed with a 1.5 N hydrochloric acid aqueous solution having the same volume as the weight of the powder, and the mixture is placed in a Teflon pressurized container, sealed, and sealed.
After hydrothermal treatment at ℃ and steam pressure of about 1 MPa for 48 hours,
It was cooled, filtered, washed with water and dried. The loss on ignition of this treated powder increased to 9.50% by weight.

Next, the hydrothermally treated powder is placed in a heating and foaming device.
Supplied. FIG. 1 shows an overall schematic view of the heating and foaming apparatus. Well
The hopper of the supply unit shown in FIG.
1 shown in FIG. 2 by the screw feeder 2.
Dispersion part cross section 1 cm on top of perforated plate 6²0.3g per
Glass solid sphere 7 with a diameter of 1.68 to 2.38 mm and dispersion
1cm section ²1g per particle size 150-210μm
A) Sand 8 is supplied to the dispersion section and the lower part of the dispersion section is supplied.
Therefore, the pressure in the lower part of the dispersion part is the pulsation number of the pressure as shown in Fig. 3.
Gives an air pulsation of 30 times / second,
At the same time, the upflow velocity of air is 16 cm / sec.
Is adjusted by the flow of air that accompanies the pulsation of air.
The dispersed particles have a foaming area cross-sectional area of 100 cm.²20 per
The vertical cylinders of are bundled and held at 1040 ° C. by the furnace 4.
Conveyed to the foaming zone.

The cooling of the heated air and foam, in order to suppress condensation of moisture in the foam recovery unit, foam zone top of the air inlet 3 of Figure 1, foam zone section 100 cm ² per 60
Liters per minute of air were introduced. The amount of introduction was adjusted by adjusting the flow rate of a suction pump directly connected to the foam recovery section having the bag filter 5.

After the foam is recovered in the foam recovery section,
Floating and sedimentation was performed in water, and fine hollow glass spheres were collected as a float. The recovery rate, whiteness, and strength of the obtained fine hollow glass spheres were measured. Table 2 shows the results.

On the other hand, as the structure of the foaming zone, the same procedure as above was carried out except that three vertical cylinders were used per 100 cm ^{2 of the} cross-sectional area of the foaming zone. The recovery rate, whiteness and strength of the fine hollow glass spheres obtained here were determined. The results are shown in Table 2.

The whiteness was calculated from the color difference measured by the Lab method, and the strength was expressed by the content ratio of non-destructive particles after holding for 1 minute under hydrostatic pressure of 8 MPa.

[0029]

[Table 2]

As can be seen from Table 2, in the foaming zone,
Increasing the number of cylinders per 100 cm ^{2 of} cross-sectional area increases the recovery rate. However, the cross-sectional area is 100 cm ^2.
Assuming that the number of cylinders per hit is 20 or more, the inside of the cylinder started to close, and the more the number of cylinders, the more the number of closed cylinders. The hollow glass sphere obtained by the method of the present invention is fine, has high whiteness, and has high strength.

Further, the upward flow velocity of the air in the foaming zone is set to 10
Even at 0 cm / sec or more, the recovery rate of the hollow glass spheres shown in Table 2 did not change. Also, set the maximum temperature in the furnace to 1
When the temperature was raised to 100 ° C, the recovery rate of the fine hollow glass spheres increased. However, at a temperature of 1100 ° C. or higher, fusion occurred in the furnace, and it was difficult to recover the heat-treated product. On the other hand, as the maximum temperature in the furnace became lower than 1040 ° C., the recovery rate of the hollow glass spheres gradually decreased and could not be recovered at 900 ° C.

As the amount of air introduced from the air inlet in the upper part of the foaming area was reduced, the bag filter was likely to be clogged, and recovery of the heated foam became difficult. By introducing air at a rate of 10 liters / min or more per 100 cm ^{2 of the} foaming area cross section, collection was efficient.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of a heating and foaming apparatus used in Examples.

FIG. 2 is a schematic view of a dispersion unit in the heat-foaming device used in the examples.

FIG. 3 is an explanatory diagram of air pulsation at a positive pressure.

[Explanation of symbols]

 1 Hopper 2 Screw feeder 3 Air inlet 4 Furnace 5 Bag filter 6 Perforated plate 7 Glass solid sphere 8 Quartz sand 9 Powder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiichi Abe 807 Nonoshita, Tojuku-cho, Tosu City, Saga Prefecture 1 Kyushu Institute of Industrial Technology (72) Inventor Kenichiro Matsuda 8-2 Goi Minami Kaigan, Ichihara, Chiba Prefecture In stock company Calceed (72) Inventor Junichi Kimoto One share company at 4611 Isa-cho, Mine-shi, Yamaguchi Prefecture Within Calceed (72) Inventor Hiromi Okada One share company at 4611 Isa-cho, Isa-cho, Yamaguchi Prefecture Within Calceed

Claims (3)

[Claims] 1. A dispersion part comprising a perforated plate filled with solid glass spheres and quartz sand, and a volcanic glassy sediment powder having a particle size of 20 μm or less is supplied from a dispersion part lower part to a dispersion part. The powder is dispersed by supplying positive pulsating air having a lower pressure and pulsating air at an ascending flow velocity of 10 to 100 cm / sec in the dispersing section, and 900 to 1100.
A method for producing fine hollow glass spheres, comprising carrying out foaming by transporting to a vertical foaming zone that maintains a temperature of ℃, and then recovering hollow bodies from this foamed product by difference in specific gravity. 2. The foaming area is 3 cm / 100 cm ² in cross-sectional area.
2. The method for producing a fine hollow glass sphere according to claim 1, wherein the method has a structure having a bundle of at least vertical tubes. 3. A foaming area having a cross section of 100 cm from the foaming area.
^The method for producing fine hollow glass spheres according to claim 1 or 2, wherein 10 liters / minute or more of air is introduced per ² .