PROCESS FOR PRODUCING GRANULES, METHOD FOR PRODUCING MOLTEN GLASS AND METHOD FOR PRODUCING GLASS PRODUCT

• US 20140075995A1
• Filed: 11/25/2013
• Published: 03/20/2014
• Est. Priority Date: 05/25/2011
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: HAYASHI, Yasuo, ANDO, Ryota
• Granted Patent: US 9,302,926 B2
• Time in Patent Office: Days
• US Class Current: 65/95
• CPC Class Codes: B01D 53/1418 Recovery of products
• CPC Class Codes: C03B 1/02 Compacting the glass batches, e.g. pelletising
• CPC Class Codes: C03B 19/102 by blowing a gas onto a stream of molten glass or onto particulate materials, e.g. pulverising
• CPC Class Codes: C03B 19/1055 by extruding, e.g. dripping molten glass in a gaseous atmosphere
• CPC Class Codes: C03B 5/16 Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
• CPC Class Codes: C03B 5/237 Regenerators or recuperators specially adapted for glass-melting furnaces
• CPC Class Codes: C03C 1/002 Use of waste materials, e.g. slags
• CPC Class Codes: C03C 3/089 containing boron
• CPC Class Codes: Y02P 40/50 Glass production, e.g. reusing waste heat during processing or shaping

Abstract

To provide a process for producing granules, wherein a component in an exhaust gas discharged from a glass melting furnace can be reused as a raw material for alkali-free glass, and a heating and drying step is not required for the reuse. Exhaust gas G1 formed in a process for melting a raw material of glass containing a boron component is brought in contact with contacting liquids L1 and L2 to obtain treated liquids S1, S2 and S3 having the boron component in the exhaust gas G1 dissolved therein; magnesium hydroxide is added to the mixture of the treated liquids in a treated liquid tank 14 to obtain a liquid containing a boron component and a magnesium component; by using the liquid, a granulation liquid is prepared; and in the presence of the granulation liquid, a raw material mixture for producing alkali-free borosilicate glass is granulated to produce granules.

Claims

1. A process for producing granules, which comprises:

an exhaust gas treating step of contacting a contacting liquid and an exhaust gas formed in a process for producing borosilicate glass by melting a glass raw material, to obtain a treated liquid having a boron component in the exhaust gas dissolved in the contacting liquid,

a magnesium hydroxide-addition step of adding magnesium hydroxide to the treated liquid to obtain a liquid containing the boron component and the magnesium component,

a granulation liquid-preparation step of preparing a granulation liquid by using the liquid containing the boron component and the magnesium component, and

a granulation step of granulating a glass raw material powder for producing alkali-free borosilicate glass in the presence of the granulation liquid.

2. The process for producing granules according to claim 1, wherein the borosilicate glass is alkali-free borosilicate glass.

3. The process for producing granules according to claim 1, wherein the alkali-free borosilicate contains at least SiO₂, B₂O₃ and MgO, and as represented by mol % based on oxides, the content of SiO₂ is from 60 to 75 mol %, the content of B₂O₃ is from 2 to 25 mol %, and the content of MgO is from 1 to 30 mol %.

4. The process for producing granules according to claim 1, wherein the granules are produced by adjusting the glass raw material powder and the granulation liquid so that glass obtainable by melting and vitrifying the granules would be alkali-free borosilicate glass having the glass composition which contains at least SiO₂, B₂O₃ and MgO, wherein as represented by mol % based on oxides, the content of SiO₂ is from 60 to 75 mol %, the content of B₂O₃ is from 2 to 25 mol %, and the content of MgO is from 1 to 30 mol %.

5. The process for producing granules according to claim 1, wherein a part of the liquid containing the boron component and the magnesium component is reused as the contacting liquid.

6. The process for producing granules according to claim 1, wherein in the magnesium hydroxide-addition step, the magnesium hydroxide is added so that the pH of the liquid containing the boron component and the magnesium component would be within a range of from 6.5 to 7.7.

7. The process for producing granules according to claim 1, wherein in the magnesium hydroxide-addition step, the liquid containing the boron component and the magnesium component is further stirred.

8. The process for producing granules according to claim 1, wherein before contacting the exhaust gas with the contacting liquid, the exhaust gas is treated by a dust collector.

9. The process for producing granules according to claim 8, wherein before the dust collector, calcium hydroxide is supplied to the exhaust gas.

10. A method for producing molten glass, which comprises melting the granules obtained by the process as defined in claim 1, to obtain molten glass.

11. The method for producing molten glass according to claim 10, wherein an exhaust gas formed by melting of the granules is used as the above exhaust gas.

12. The method for producing molten glass according to claim 10, wherein the granules are put onto a molten glass liquid surface in the melting furnace and melted.

13. The method for producing molten glass according to claim 10, wherein at least a part of the granules is melted in a gas phase atmosphere to form molten glass particles, and the molten glass particles are collected to obtain molten glass.

14. A method for producing a glass product, which comprises forming the molten glass obtained in the method for producing molten glass as defined in claim 10, followed by annealing.

15. The method for producing a glass product according to claim 14, wherein the molten glass is formed into a plate-form by a float process.