KR20030071703A - Method and apparatus for Fabrication of Hollow Glass Sphere - Google Patents

Abstract

PURPOSE: Provided is a production method of hollow glass spheres by spray-drying liquid glass precursors, spraying powder particles from the top to the bottom of flame furnace, and recovering at the bottom of the furnace unlike conventional recovering. Accordingly, the method increases the recovery of hollow glass spheres with homogeneity, simplifies production apparatus and enables mass production. CONSTITUTION: The hollow glass spheres are produced by the following steps of: dissolving 2.0-3.8wt.% of boric acid into 30.6-40.7wt.% of water; adding a boric acid solution to 56-67wt.% of water glass for a water glass solution; adding 0.4-1.9wt.% of urea and mixing for 0.5-1hr. to prepare liquid precursors; spray-drying the liquid at 200-250deg.C; preheating the prepared particles; spraying powder particles from the top to the bottom of a flame furnace at 900-1300deg.C for 0.2-0.5sec, wherein burners are set along the innerwall of the furnace; recovering the formed hollow glass spheres at the bottom of the furnace through cyclone and collector.

Description

Method and apparatus for fabricating glass hollow spheres {Method and apparatus for Fabrication of Hollow Glass Sphere}

The present invention provides a method for producing a glass hollow sphere, characterized in that the liquid precursor mixed with water, water glass, boric acid and urea to produce a raw material particles by spray drying, and to form a glass hollow sphere by using a firing furnace for falling Relates to a device.

Hollow Glass Sphere has a hollow shape and is a composite mixed with materials such as synthetic resin and cement because of its low density, low dielectric constant and excellent thermal insulation, chemical durability and mechanical strength. It is widely used in ultra insulation materials, thermal insulation materials, and the like.

In general, as a method for preparing raw material particles for producing glass hollow spheres, i) frit by pulverizing solids obtained by putting waste glass in a melting furnace at a temperature of about 1,500 ° C and quenching it into water. ), Ii) preparing raw materials such as water glass, boric acid and urea, mixing them with water to make an aqueous solution, drying them at a low temperature of about 300 ° C. to obtain solids and grinding them to obtain frits. Method, i) a method of directly obtaining spherical granular particles by spraying a liquid raw material into fine droplets in a high temperature drying medium of a spray dryer.

Of the above methods, the spray drying process is suitable for continuous mass production, and is the most widely used process because it is very simple compared to the drying method of other processes. The domestic patent applications for the actual glass hollow sphere manufacturing technology are patents that improve the process, Korean Patent Publication No. 92-11934 discloses a silica source such as surfactant, sodium silicate colloidal silica powder, silica sol, alkali metal or alkali A method of forming aesthetics by mixing a metal cation compound, a boron-containing compound of earth metal and urea, and spraying a solution or dispersion through a nozzle, and Korean Patent Laid-Open Publication No. 2003-32193 consists of water glass, water, boric acid and urea. The present invention relates to a method for producing glass hollow spheres by forming raw material particles using a frit method or spray drying using a mixture.

The above methods for manufacturing glass hollow spheres are methods of recovering glass hollow spheres by raising glass hollow spheres formed by spraying raw material particles at the bottom or middle of a gas flame furnace to a duct at the top of the firing furnace. Since glass hollow spheres are recovered by raising the glass hollow spheres upward from the bottom, the recovery rate of glass hollow spheres is low due to the load of gravity, and nitrogen gas is used as a carrier gas or oxygen as a combustion gas to transfer raw material particles. Because of the use of gas, not only gas is expensive, but also difficult to manufacture the equipment, there was a problem that is difficult to apply to mass production on site.

The present invention has been made in order to solve the above problems, the raw material particles are produced by spray drying the liquid precursor mixed with water, water glass, boric acid and urea, and the raw material particles to the upper end of the kiln by using the firing furnace for falling It relates to a method and apparatus for producing a glass hollow sphere, characterized in that to form a glass hollow sphere by spraying at the lower end to recover the glass hollow sphere at the bottom of the firing furnace.

It is still another object of the present invention to provide a method and apparatus for manufacturing a glass hollow sphere, wherein the raw material particles are preheated in a preheater before the raw material particles are dispersed in a disperser, so that the raw material particles can be well dispersed in a firing furnace. have.

Still another object of the present invention is to manufacture a glass hollow sphere, characterized in that the production equipment is simply manufactured by using air as a conveying gas and conveying raw material particles using a conveyor, so as to be suitable for mass production in the field. And to provide an apparatus.

1 is a manufacturing process of the glass hollow sphere according to the present invention.

Figure 2 is an apparatus for producing a glass hollow sphere according to the present invention.

3 is a detailed view of the burner of FIG.

Figure 4 is a graph of the water resistance measurement results of the glass hollow sphere according to the present invention.

5 is a graph of the result of measuring the strength of the glass hollow sphere according to the present invention.

Figure 6a is a SEM (Scanning Electron Micrograph) photograph confirming that the glass hollow sphere prepared according to the present invention.

Figure 6b is a SEM (Scanning Electron Micrograph) photographs observed that the glass hollow spheres produced in accordance with the present invention was broken.

Explanation of symbols on the main parts of the drawings

1: raw material inlet 2: preheater

3: disperser 4: burner

5: LNG gas storage 6: cyclone

7: dust collector 8: blower

9: furnace inner wall 10 furnace furnace wall

11: nozzle 12: gas regulator

13: conveyor 14: firing furnace

In the present invention, raw material particles are produced by spray-drying a liquid precursor mixed with water, water glass, boric acid, and urea, and the glass particles are formed by spraying the raw material particles from the upper end to the lower end of the firing furnace using a descending firing furnace. It relates to a method and apparatus for producing a glass hollow sphere, characterized in that to recover the glass hollow sphere at the bottom of the kiln.

Method for producing a glass hollow sphere in the present invention is as follows.

30.6 to 40.7% by weight of water, 56.0 to 67.0% by weight of water glass, 2.0 to 3.8% by weight of boric acid, and 0.4 to 1.9% by weight of urea were mixed and warmed to 60 to 65 ° C to prepare a liquid precursor, which was about 200 to 250 ° C. Raw particles are produced by spray drying at low temperatures. The raw material particles prepared in the spray drying method are sprayed to the lower end by dispersing the raw material particles through a disperser installed at the top of the firing furnace while maintaining the temperature inside the firing furnace at 900 to 1,300 ° C., and then recovered from the bottom of the firing furnace.

Looking at the raw materials used in the present invention in detail.

The content of water used in the present invention is 30.6 to 40.7% by weight, preferably 32 to 37% by weight. When the content of water is less than 30.6% by weight, a large amount of precipitates are generated, and it takes a long time to react. When the content of water exceeds 40.7% by weight, the solid content of the entire solution decreases, which requires a large amount of heat during spray drying.

The content of water glass used in the present invention is 56.0 to 67.0% by weight, preferably 59.0 to 63.0% by weight. Water glass is a parent material of glass hollow spheres, and the content of water, boric acid and urea is adjusted according to the content of water glass.

Boric acid used in the present invention serves to increase the strength of the hollow spheres and to improve the resistance to moisture, the content is 2.0 to 3.8% by weight, preferably 2.8 to 3.3% by weight. When the content of boric acid is less than 2.0% by weight, it is impossible to increase the strength of the hollow spheres or increase the resistance to moisture, and when the content of the boric acid exceeds 3.8% by weight, boric acid is dissolved and precipitated again.

Urea used in the present invention serves as a blowing agent, the content is 0.4 to 1.9% by weight, preferably 0.9 to 1.4% by weight. When the content of urea is less than 0.4% by weight, effective foaming of the hollow spheres is not achieved. When the content of the urea exceeds 1.9% by weight, the hollow spheres expand too much to have the shape of the hollow spheres.

Referring to the manufacturing process for forming the glass hollow sphere in the present invention in detail with reference to the accompanying drawings as follows.

1 is related to the manufacturing process chart of the glass hollow sphere according to the present invention.

Iii) adding 2.0 to 3.8 wt% of boric acid in 30.6 to 40.7 wt% of water at 60 to 65 ° C to completely dissolve to prepare a boric acid solution;

Ii) slowly dissolving the boric acid solution prepared in i) in 56.0 to 67.0% by weight of water glass maintained at 60 to 65 ° C. to completely dissolve them, thereby preparing a water glass solution;

Iii) adding urea to the water glass solution prepared in ii) and mixing the mixture for 0.5 to 1 hour to prepare a liquid precursor;

Iii) injecting the liquid precursor prepared in iii) into a spray dryer and preparing powder particles; At this time, the temperature of the spray dryer is maintained at about 200 to 250 ℃.

Iii) preheating the powder particles prepared by spray drying in iii) with a preheater,

Iii) a high heat treatment while dispersing the powder particles to the bottom of the furnace through a disperser installed at the top of the kiln to form a glass hollow sphere; At this time, the temperature inside the kiln is approximately 900 to 1,300 ° C, and the time for the particle powder to pass through the flame is approximately 0.2 to 5.0 seconds.

The glass hollow sphere of the present invention is produced through the steps of i) to i).

The reason for maintaining the temperature of water at 60 to 65 ℃ in iv) and ii) is to maximize the solubility of the raw material particles, and in order to produce a uniform spherical powder particles in the iv) the temperature of the spray dryer 200 Spraying is maintained at about 250 ℃, the temperature inside the suitable firing furnace for the production of glass hollow sphere in the vi) is 900 to 1,300 ℃, if the temperature is lower than 900 ℃ powder particles are sufficiently heated within the given residence time in the firing furnace , It does not expand and does not form a sufficient spherical bubble is formed inside the exit of the kiln as it is, when higher than 1,300 ℃ powder particles will not form a sufficient spherical melt.

6 is a SEM (Scanning Electron Micrograph) photograph taken to observe the microstructure of the glass hollow sphere prepared by the above method, Figure 6a is a photograph showing only the glass hollow sphere prepared in accordance with the present invention, Figure 6b Is a photograph taken by crushing the glass hollow sphere prepared according to the present invention to confirm that the hollow sphere.

The firing furnace for manufacturing the glass hollow sphere in the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 relates to a manufacturing apparatus for producing a glass hollow sphere according to the present invention, the manufacturing apparatus of the present invention is a disperser in the center of the raw material feeder (1), preheater (2), conveyor (13) and the upper interior of the furnace (3) and a circular burner (4) with several nozzles formed around the inner wall slightly below, and a firing furnace (14) provided with a blower (8) for supplying air as a combustion gas at the lower part and a cyclone for recovering the glass hollow spheres. 6, a dust collector 7, an LNG gas reservoir 5 for storing and supplying fuel gas, a gas regulator 12, and a blower 8 for supplying air which is a combustion gas.

In the above, the raw material injector 1 is a means for injecting the powder particles produced in the spray dryer, the preheater 2 is a means for preheating the powder particles to be introduced into the firing furnace 14, the conveyor 13 is a powder particle It is a means for conveying from the raw material inlet 1 to the disperser 3.

In the firing furnace 14, a disperser 3 for injecting powder particles is installed in the center of an inlet formed in a circular shape at the top of the furnace, and a plurality of nozzles are provided in the main body as shown in FIG. Burners 4 formed at regular intervals 11 are installed in a circular shape along the inner wall of the furnace, and on one side of the burner 4, a gas regulator 12 and an LNG gas reservoir 5 for supplying LNG gas. Burner 4 located at the lower part of the top of the kiln 14 from the bottom of the kiln 14 through a space formed between the furnace inner wall 9 and the furnace outer wall 10 at the lower part of the kiln 14. A blower 8 for supplying air, which is a combustion gas, is installed in the reactor, and a cyclone 6 and a dust collector 7 are installed at one side of the lower end of the kiln 14 to recover the glass hollow spheres formed in the kiln 14. It is done.

The flow of air in the kiln 14 is caused by the suction force sucked by the dust collector 7 from the blower 8 installed in the lower part of the furnace as shown by the arrow shown in FIG. 2, and the furnace inner wall 9 and the furnace outer wall 10. After being introduced into the furnace through the burner 4 located slightly below the upper part of the furnace through the space formed therebetween, it moves to the lower part of the furnace and passes through the cyclone 6 through the dust collector 7. And the glass hollow sphere formed in the furnace is also moved with the flow of air in the furnace is recovered from the cyclone (6).

The burner 4 used in the present invention has a plurality of nozzles 11 formed in the main body at regular intervals toward the middle of the furnace, and the burners 4 are installed in a circular shape along the inside of the furnace inner wall. Heat is transmitted by the flame injected into the center of the furnace in the evenly distributed to the raw material particles, it is possible to obtain a glass hollow sphere having a uniform, excellent physical properties.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by Examples.

(Examples 1-3 and Comparative Examples 1-3)

1. Preparation of Liquid Precursors

A boric acid solution is prepared by completely dissolving a certain amount of boric acid in a predetermined amount of water at 60 to 65 ° C. Then, the boric acid solution prepared above is slowly added to a certain amount of water glass maintained at 60 to 65 ° C to completely dissolve them. After the water glass is completely dissolved in the boric acid solution, a certain amount of urea is added and mixed sufficiently for 0.5 to 1 hour to prepare a liquid precursor. The mixing ratio of water, water glass, boric acid and urea used above is shown in Table 1 below.

TABLE 1

(Unit: weight%)

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 water 400 400 400 400 400 400 water glass 700 700 700 700 700 700 Boric acid 35 30 25 15 10 5 Element 12 12 12 12 12 12

2. Preparation of Raw Particles

The liquid precursors of Examples 1 to 3 and Comparative Examples 1 to 3 prepared above were added to the spray dryer under the same conditions, and raw material particles were prepared to be powder. At this time, the temperature of the spray dryer is maintained at about 200 to 250 ℃.

3. Preparation of Glass Hollow Spheres

The glass hollow spheres formed by spraying the raw material particles prepared by the mixing ratio of Table 1 to the lower end through the sprayer installed at the upper end of the firing furnace in which the nozzles are formed at regular intervals are installed at the lower end of the firing furnace. At this time, the temperature inside the kiln was maintained at about 1,050 to 1,100 ° C, and the time for the particle powder to pass through the flame was about 0.2 to 5.0 seconds.

Measurement of the water resistance of the glass hollow spheres prepared according to the above Examples and Comparative Examples measured the pH after 1 hour to put 5% by volume glass hollow spheres in distilled water at 25 ℃. As shown in FIG. 4, in Example 1, the pH was 9.6, and in Example 3, the pH was close to 9.8. However, in Comparative Example 1 to Comparative Example 3, the pH increased sharply, so that the pH was 10.6. It turned out to be abnormal.

The lower the amount of boric acid added to the glass hollow spheres, the higher the pH of Na ₂ O eluted from the glass hollow spheres. It can be seen that the higher the water resistance is worse.

In addition, the strength measurement of the glass hollow sphere prepared in Example 1 to collect only the hollow spheres floating in water to measure the weight, and to increase the pressure by 50psi pressure unit using a low pressure isostatic pressing machine to apply the pressure to the isostatic pressure Pressure was applied, and only the glass hollow spheres floating in the water without breaking at each pressure were collected and weighed. Then, the residual ratio (%) was calculated by comparing the initial weight with the remaining weight without destruction.

As shown in FIG. 5, as a result of the strength measurement of the residual percentage (%) of the glass hollow spheres remaining unbreakable at each pressure, the residual ratio of the glass hollow spheres was almost 90% up to 500 psi, but remained above 500 psi. It can be seen that the rate decreases rapidly.

The present invention is to recover the glass hollow sphere at the bottom by spraying the raw material particles from the top of the kiln to the bottom, so that the recovery rate of the glass hollow sphere is high under no load of gravity, and the raw material in the preheater before dispersing the raw particles at the top of the kiln By preheating the particles, the raw material particles are well dispersed in the firing furnace, and the heat of the flame sprayed from the burner composed of nozzles provided at regular intervals is evenly transmitted to the raw material particles, thereby obtaining a glass hollow sphere having uniform and excellent physical properties. It can be effective.

In particular, the present invention has an advantage in that it is possible to easily manufacture the production equipment by using the conveyor as a raw material for transporting the raw material particles and the combustion gas, and to make it suitable for mass production in the field.

Claims (8)

Iii) adding boric acid to water to dissolve it completely to prepare a boric acid solution; Ii) slowly dissolving the boric acid solution prepared in iii) into the water glass to completely dissolve them to prepare a water glass solution; Iii) adding urea to the water glass solution prepared in ii) and mixing the mixture for 0.5 to 1 hour to prepare a liquid precursor; Iii) injecting the liquid precursor prepared in iii) into a spray dryer and preparing powder particles; Iii) preheating the powder particles prepared by spray drying in iii) with a preheater; Iii) heat treating the powder particles to the lower part of the furnace through a disperser installed at the upper part of the kiln to form glass hollow spheres; Iii) recovering the formed glass hollow sphere at the bottom of the kiln; Method for producing a glass hollow sphere, characterized in that it comprises a. The method of claim 1, wherein the step iii) is 30.6 to 40.7 wt% of water, 56.0 to 67.0 wt% of water glass, 2.0 to 3.8 wt% of boric acid, and 0.4 to 1.9 wt% of urea. The method for producing a glass hollow sphere according to claim 1, wherein an appropriate temperature for preparing a liquid precursor in steps iii), ii) and iii) is 60 to 65 ° C. The method of claim 1, wherein the temperature of the spray drying for preparing the powder particles in step iii) is 200 to 250 ℃. The method according to claim 1, wherein the firing temperature for forming the glass hollow sphere in step iii) is 900 to 1,300 ° C, and the flame passage time of the powder particles in the firing furnace is 0.2 to 5.0 seconds. . Raw material feeder (1), preheater (2), conveyor (13) and a circular burner (4) formed with a disperser (3) in the middle of the upper part of the furnace, and several nozzles in the inner wall of the lower part, and the combustion gas air in the lower part of the furnace. A kiln 14 equipped with a blower 8 for supplying gas, a cyclone 6 and a dust collector 7 for recovering glass hollow spheres, an LNG gas storage 5 for storing fuel gas, and a quantity of fuel gas supplied Apparatus for producing a glass hollow sphere, characterized in that it comprises a gas regulator (12) and a blower (8) for supplying air which is a combustion gas. The burner (4) is characterized in that the burner (4) formed in a circular shape along the inside of the furnace inner wall is formed with a plurality of nozzles (11) in the main body at regular intervals toward the center of the furnace. Device for producing glass hollow spheres. The glass hollow sphere according to claim 6, wherein the firing furnace (14) has a space formed between the furnace inner wall (9) and the furnace outer wall (10) so that air supplied from the blower (8) installed in the lower portion can pass therethrough. Manufacturing apparatus.