CA1069307A - Method of making glass - Google Patents
Method of making glassInfo
- Publication number
- CA1069307A CA1069307A CA239,554A CA239554A CA1069307A CA 1069307 A CA1069307 A CA 1069307A CA 239554 A CA239554 A CA 239554A CA 1069307 A CA1069307 A CA 1069307A
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- CA
- Canada
- Prior art keywords
- glass
- additive
- molten
- composition
- ingredients
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/18—Stirring devices; Homogenisation
- C03B5/187—Stirring devices; Homogenisation with moving elements
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
- C03B5/173—Apparatus for changing the composition of the molten glass in glass furnaces, e.g. for colouring the molten glass
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C13/00—Fibre or filament compositions
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/50—Optics for phase object visualisation
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G16/00—Electrographic processes using deformation of thermoplastic layers; Apparatus therefor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/10—Cameras or camera modules comprising electronic image sensors; Control thereof for generating image signals from different wavelengths
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/80—Television signal recording using electrostatic recording
- H04N5/82—Television signal recording using electrostatic recording using deformable thermoplastic recording medium
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Optics & Photonics (AREA)
- Glass Compositions (AREA)
- Glass Melting And Manufacturing (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a method for producing a fiber-izable borosilicate glass in which the constituents of the glass composition are classified into two or more melting groups. A
molten base glass portion which is free of at least a major por-tion of the boric oxide yielding ingredients is prepared, and the remainder of the glass composition including the boric oxide yielding ingredients is introduced and homogenized with the molten base glass external to the base glass melting area, there-by to form a molten glass composition of desired characteristics.
The invention is particularly adaptable to the formation of boro-silicate glass fibers; the ingredients for the glass fiber are separated into those for forming a host glass and those for form-ing a B2O3-containing additive glass. The ingredients for the host glass are melted in a continuous flow main-melter and flowed from the main-melter to a location where the fibers are to be formed. The additive glass is separately melted, and combined (with forceful mechanical mixing) with a larger portion of the molten host glass prior to the fiber-forming location, to form a fiberizable borosilicate glass. Since at least a major propor-tion B2O3 content of the fiber is supplied by the additive glass, the main-melter exhibits longer life and the volatilization losses of B2O3 are substantially less than when the ingredients of the additive and host glass are melted together in the main-melter.
The invention provides a method for producing a fiber-izable borosilicate glass in which the constituents of the glass composition are classified into two or more melting groups. A
molten base glass portion which is free of at least a major por-tion of the boric oxide yielding ingredients is prepared, and the remainder of the glass composition including the boric oxide yielding ingredients is introduced and homogenized with the molten base glass external to the base glass melting area, there-by to form a molten glass composition of desired characteristics.
The invention is particularly adaptable to the formation of boro-silicate glass fibers; the ingredients for the glass fiber are separated into those for forming a host glass and those for form-ing a B2O3-containing additive glass. The ingredients for the host glass are melted in a continuous flow main-melter and flowed from the main-melter to a location where the fibers are to be formed. The additive glass is separately melted, and combined (with forceful mechanical mixing) with a larger portion of the molten host glass prior to the fiber-forming location, to form a fiberizable borosilicate glass. Since at least a major propor-tion B2O3 content of the fiber is supplied by the additive glass, the main-melter exhibits longer life and the volatilization losses of B2O3 are substantially less than when the ingredients of the additive and host glass are melted together in the main-melter.
Description
~069307 The present invention relates to an improved method for preparing molten glass compositions. Heretofore, molten glass compositions have been prepared by charging a batch formulation into a glass melter or furnaca wherein heat is applied in suffi-cient quantity to cause the batch ingredients to react with each other and form a mass of molten constituents. The resuiting molten mass is then homogenized or refined within the melting apparatus to form the desired molten glass composition.
In the mass production of glass products preparation of - 10 molten glass is preferably a continuous process wherein the melt-ing unit contains a reservoir of molten constituents into which ' the batch formulation is charged at a rate responsive to the i molten glass withdrawal or pull rate. During the time the molten '; constituents reside within the melter they further react with one another forming a homogenized molten glass of the desired compo-sition. A typical constituent residence time for a melter pro-ducing 150 tons of molten glass per day is approximately 24 to 48 hours or greater. The temperature of the molten constituents re-siding in the melter must be maintained at a sufficient level to react the incoming batch ingredients. ~ence, molten constituents which volatilize at temperatures below the established melter oper- ~-ating temperature-escape as flue gas. Therefore, to obtain a given molten glass composition suitable for forming, the batch formulation must compensate for the proportion of constituents lost by volatiliza~ion during melter residence. Therefore, the present glass melting methods restrict molten glass compositions to compositions containing only those constituents which can sur-vive the environment of the glass melting apparatus. By cur-rently known methods of preparing molten glass having particular properties or forming characteristics it is necessary to S~
106930'7 introduce into the melting furnace all of the constituents that must be present in the final molten glass composition to produce those properties or characteristics. Many times the presence of those constituents in the melter is undesirable because of their volatility, corrosiveness, and environmental effects. ;~
For example, molten glass compositions suitable for glass fiber manufacture generally contain volatile constituents such as boron oxide (B2O3), fluorine (F2), and sodium borate (Na2O xB2O3). These constituents not only volatilize at melter operating temperatures but also their presence in the melt shortens melter life by chemical attack upon refractory materials.
The present invention relates to an improved method for preparing molten glass compositions whereby the constituents are ~ classified into two or more groups; each group containing consti-; tuents having similar reactive characteristics. The classifica-tion may be based upon volatilization temperature of the consti-tuents or other mutual characteristic such as corrosiveness or catalytic action. The classification criteria of one group need not necessarily be mutually exclusive of other constituent groups.
For example, if the constituents are classified according to volatilization temperature, the temperature range of a given constituent group may extend into the temperature range of the next higher or next lower group. Thus, two constituent groups may include a common constituent.
Applying the principles of this invention to the pre-paration of a molten fiberizable glass composition comprising silicon oxide (SiO2), aluminum oxide (A12O3), calcium oxide (CaO), boron oxide (B2O3), fluorine (F2) and sodium oxide (Na2O), two melting groups may be identified. The highly volatile consti-tuents B2O3, F2 and Na2O xB2O3 are preferably grouped together C
as a volatile oxide group. The remaining constituents SiO2, A12O3, Na2O and CaO may be grouped together as a relatively non-volatile group. By this grouping of constituents the non-vola-tile group is recognized as soda lime glass, a glass composition common to the glass industry.
In this method of preparing a molten fi~erizable glass composition comprising the above constituents, the relatively non-volatile constituent group is preferably prepared as a molten base glass in a glass melting fu~nace of the continuoùs type common to the glass-making industry. To this relatively non- ~ -volatile molten base glass composition the volatile constituent group is added either as a molten composition or as a batch for-mulation. The volatile constituent group may be introduced into the molten base glass composition at any convenient location downstream of the non-volatile constituent group's melting area.
Preferably the volatlle constituent group is introduced into the molten base glass immediately downstream of the base glass melter's exit throat thereby taking advantage of the base glass' exit temperature and residual heat. However, the volatile con-stituent group might be introduced directly into the base glass melter's throat area or any other favorable or otherwise advan-tageous location along the forehearth distribution channel.
By this method of glass making it is no longer neces-sary to melt all of the desired glass composition's constituents in a common glass melter as one all-inclusive batch formulation.
A less hostile batch may be specifically formulated for melting in the main melter without ~he restrictions heretofore imposed by the final molten glass composition. Molten glass may now be substantially modified downs~ream of the main glass melting area, thereby obtaining a molten glass composition having different ~ !
~06930~
properties or forming characteristics. -~
Therefore, in accordance with the present invention, a method of producing a fiberizable borosilicate glass includes the steps of melting a base portion of the glass composition free of at least a major portion of the boric oxide yielding ingre-dients, introducing as an additive portion the remainder of the glass composition including the boric oxide yielding ingredient, and mixing and homogenizing the additive portion with the molten base glass in proportions to form the borosilicate glass of desired composition. More specifically, this invention provides a method of forming a fiberizable borosilicate glass which in-cludes the steps of separating batch ingredients for the glass into ingredients for forming a host glass and for forming a B203-containing additive glass, melting those ingredients for forming the host glass in a generally horizontally-disposed, continuous flow, main melter, flowing the molten host glass from the main melter to a location where glass fibers are formed, separately melting the additive glass and combining, with forceful mechani-cal mixing, the molten additive glass with a larger portion of the molten host glass prior to the fiber-forming location to form a fiberizable borosilicate glass, and forming borosilicate fiber at the fiber-forming location from the fiberizable glass, whereby at least a major proportion of the B203 content of the fiber is supplied by the additive glass, the melter exhibits longer life, and the volatilization losses of B203 are substan-tially less than that which results when melting the ingredients of the additive and host glass together in the melter.
Although the following exemplary discussion will be primarily directed to two common fiberizable molten glass compo-sitions, one for glass wool production and the other for glass ~' .
~",J
~a6s307 fiber textiles, it should be understood that in accordance withthe broad principles of the present invention many other fiberizable and non-fiberizable glass compositions also may be prepared in a similar manner.
A common molten glass composition used in the manufac-ture of glass wool insulation, except for tramp materials, is:
Constituent Percent by Weight SiO261.5 4.0 : ;
CaO 8.0 MgO 3.5 .
Na2O14.5 ::
K20 1. 0 - '~
B2O3 7.5 l~he primary volatile from the above molten glass compo-sition is sodium borate which forms by the reactionof Na2O and B2O3. Accounting for the presence of sodium borate, the molten glass composition~may be written as:
: : Constituent Percent by Weight ~:-: SiO2 61.5 -
In the mass production of glass products preparation of - 10 molten glass is preferably a continuous process wherein the melt-ing unit contains a reservoir of molten constituents into which ' the batch formulation is charged at a rate responsive to the i molten glass withdrawal or pull rate. During the time the molten '; constituents reside within the melter they further react with one another forming a homogenized molten glass of the desired compo-sition. A typical constituent residence time for a melter pro-ducing 150 tons of molten glass per day is approximately 24 to 48 hours or greater. The temperature of the molten constituents re-siding in the melter must be maintained at a sufficient level to react the incoming batch ingredients. ~ence, molten constituents which volatilize at temperatures below the established melter oper- ~-ating temperature-escape as flue gas. Therefore, to obtain a given molten glass composition suitable for forming, the batch formulation must compensate for the proportion of constituents lost by volatiliza~ion during melter residence. Therefore, the present glass melting methods restrict molten glass compositions to compositions containing only those constituents which can sur-vive the environment of the glass melting apparatus. By cur-rently known methods of preparing molten glass having particular properties or forming characteristics it is necessary to S~
106930'7 introduce into the melting furnace all of the constituents that must be present in the final molten glass composition to produce those properties or characteristics. Many times the presence of those constituents in the melter is undesirable because of their volatility, corrosiveness, and environmental effects. ;~
For example, molten glass compositions suitable for glass fiber manufacture generally contain volatile constituents such as boron oxide (B2O3), fluorine (F2), and sodium borate (Na2O xB2O3). These constituents not only volatilize at melter operating temperatures but also their presence in the melt shortens melter life by chemical attack upon refractory materials.
The present invention relates to an improved method for preparing molten glass compositions whereby the constituents are ~ classified into two or more groups; each group containing consti-; tuents having similar reactive characteristics. The classifica-tion may be based upon volatilization temperature of the consti-tuents or other mutual characteristic such as corrosiveness or catalytic action. The classification criteria of one group need not necessarily be mutually exclusive of other constituent groups.
For example, if the constituents are classified according to volatilization temperature, the temperature range of a given constituent group may extend into the temperature range of the next higher or next lower group. Thus, two constituent groups may include a common constituent.
Applying the principles of this invention to the pre-paration of a molten fiberizable glass composition comprising silicon oxide (SiO2), aluminum oxide (A12O3), calcium oxide (CaO), boron oxide (B2O3), fluorine (F2) and sodium oxide (Na2O), two melting groups may be identified. The highly volatile consti-tuents B2O3, F2 and Na2O xB2O3 are preferably grouped together C
as a volatile oxide group. The remaining constituents SiO2, A12O3, Na2O and CaO may be grouped together as a relatively non-volatile group. By this grouping of constituents the non-vola-tile group is recognized as soda lime glass, a glass composition common to the glass industry.
In this method of preparing a molten fi~erizable glass composition comprising the above constituents, the relatively non-volatile constituent group is preferably prepared as a molten base glass in a glass melting fu~nace of the continuoùs type common to the glass-making industry. To this relatively non- ~ -volatile molten base glass composition the volatile constituent group is added either as a molten composition or as a batch for-mulation. The volatile constituent group may be introduced into the molten base glass composition at any convenient location downstream of the non-volatile constituent group's melting area.
Preferably the volatlle constituent group is introduced into the molten base glass immediately downstream of the base glass melter's exit throat thereby taking advantage of the base glass' exit temperature and residual heat. However, the volatile con-stituent group might be introduced directly into the base glass melter's throat area or any other favorable or otherwise advan-tageous location along the forehearth distribution channel.
By this method of glass making it is no longer neces-sary to melt all of the desired glass composition's constituents in a common glass melter as one all-inclusive batch formulation.
A less hostile batch may be specifically formulated for melting in the main melter without ~he restrictions heretofore imposed by the final molten glass composition. Molten glass may now be substantially modified downs~ream of the main glass melting area, thereby obtaining a molten glass composition having different ~ !
~06930~
properties or forming characteristics. -~
Therefore, in accordance with the present invention, a method of producing a fiberizable borosilicate glass includes the steps of melting a base portion of the glass composition free of at least a major portion of the boric oxide yielding ingre-dients, introducing as an additive portion the remainder of the glass composition including the boric oxide yielding ingredient, and mixing and homogenizing the additive portion with the molten base glass in proportions to form the borosilicate glass of desired composition. More specifically, this invention provides a method of forming a fiberizable borosilicate glass which in-cludes the steps of separating batch ingredients for the glass into ingredients for forming a host glass and for forming a B203-containing additive glass, melting those ingredients for forming the host glass in a generally horizontally-disposed, continuous flow, main melter, flowing the molten host glass from the main melter to a location where glass fibers are formed, separately melting the additive glass and combining, with forceful mechani-cal mixing, the molten additive glass with a larger portion of the molten host glass prior to the fiber-forming location to form a fiberizable borosilicate glass, and forming borosilicate fiber at the fiber-forming location from the fiberizable glass, whereby at least a major proportion of the B203 content of the fiber is supplied by the additive glass, the melter exhibits longer life, and the volatilization losses of B203 are substan-tially less than that which results when melting the ingredients of the additive and host glass together in the melter.
Although the following exemplary discussion will be primarily directed to two common fiberizable molten glass compo-sitions, one for glass wool production and the other for glass ~' .
~",J
~a6s307 fiber textiles, it should be understood that in accordance withthe broad principles of the present invention many other fiberizable and non-fiberizable glass compositions also may be prepared in a similar manner.
A common molten glass composition used in the manufac-ture of glass wool insulation, except for tramp materials, is:
Constituent Percent by Weight SiO261.5 4.0 : ;
CaO 8.0 MgO 3.5 .
Na2O14.5 ::
K20 1. 0 - '~
B2O3 7.5 l~he primary volatile from the above molten glass compo-sition is sodium borate which forms by the reactionof Na2O and B2O3. Accounting for the presence of sodium borate, the molten glass composition~may be written as:
: : Constituent Percent by Weight ~:-: SiO2 61.5 -
2 3 4.0 CaO 8.0 MgO 3,5 K2O 1.0 Na2011. O
~Na2O 3.5 2 3 7.5 *Sodium borate constituents In accordance with the present invention the consti-tuents may be classified into two melting groups having the ,r~ .
1069307 r '' ' following percentage compositions (not including minor impurities):
Group I (non-volatile constituents) Constitllent Percent by Weight SiO2 69.0 2 3 4.5 CaO 9.0 MgO 3.9 K2O - 1.1 Na2O 12.3 10Group II (volatile constituents~
Constituents Percent by Weight Na2O 32~0 2 3 67.0 -The group I composition is identifiable as a soda lime silica glass closely resembling plate glass compositions which although fiberizable is unsuitable as an insulating wool. How-ever, it is~less hostile to prepare than the insulating wool glass composition given above. The group II composition, how-ever, is highly volatile and corrosive. Therefore, the group I
constltuents are prepared as a molten base glass composition in a continuous glass melting unit common to the glass-making industry. The sodium borate constituents of group II are then introduced into the molten base glass composition of group I
either as a melt or raw batch formulation.
Since the volatile constituents of group II represent only 11% by weight of the total glass composition, they may be melted in a significantly smaller melting unit and at a substan-tially lower operating temperature. Thus, there will be less sodium borate loss by volatilization simplifying the task of pollutant elimination.
,. -.: . . .. .. .
Further, since the soda lime silica glass of group I is ~ - approximately half as corrosive as the insulating wool glass composition, one may expect a 100% increase in melter refractory :
life.
By way of further example, a common fiberizable glass composition for glass fiber textile production is:
Constituent Percent by Weight ~.
Si2 55.0 A123 15.0 :
CaO 22.0 .
2 3 7.0 F2 0.5 ~:
0.5 :
The volatile constituents of concern within this molten glass composition are B2O3, F2 and Na2O. Therefore, similar to ~ , the wool glass example above, two melting groups may be identi- ~:
fied as follows:
Group I (non-volatile constituents) Constituent Percent by Weight ~ ;
SiO2 60.0 A123 16.3 ~-CaO 23.7 Group II (volatile constituents) Constituent Percent by Weight B2O3 87.5 .
F2 6.25 Na2O 6.25 By the above grouping the hignly volatile constituents of group II, representing 8% by weight of the desired fiberizable -molten glass composition, may be separately prepared in a rela-. , ~ . .. ,, . ,.. . -. ~ . . . , . - .. . -. ,.: , ,.. ;.: . . .-, , . ., :: , . - ::
106~307 tively small melter and added to the molten base glass composi-tion realizing similar benefits as in preparation of the wool glass composition. However, further advantages are possible by reformulating the molten base glass composition of group I to obtain a eutectic composition in the CaO - Al2O3 - SiO2 system as follows:
Constituent- Percent by Weight SiO2 62.0 2 3 15.0 CaO 23.0 ~ ;
Adding the remnant constituents to the group II composi-tion it now becomes:
ConstituentPercent by Weight SiO2 13.0 CaO 12.9 A123 12.3 2 3 54.0 F2 3.9 Na2O 3.9 Thus, by selective grouping of the textile molten glass constituents we obtain a eutectic base glass composition, there-by lowering the main melter operating temperature. Further, this formulation allows the use of less expensive raw materials, such ascolemanite, as a partial source of B2O3, reducing the need for more expensive boric acid.
Accompanying Figs. l to 5 presentpreferred apparatus for introducing the molten additive composition into the molten base `
glass and homogenizing the mixture to obtain the final desired molten glass composition. In the drawings:
Figure l shows a typical glass fiber-forming operation embodying (~ ~
106i9307 ;
the present invention;
Figure 2 is a pictorial view showing the general configuration of preferred forehearth mixing apparatus for practising the invention;
Figure 3 is a schematic plan view of the forehearth mixing apparatus; -~
; Figure 4 presents a side elevation taken along line 4-4 of Figure
~Na2O 3.5 2 3 7.5 *Sodium borate constituents In accordance with the present invention the consti-tuents may be classified into two melting groups having the ,r~ .
1069307 r '' ' following percentage compositions (not including minor impurities):
Group I (non-volatile constituents) Constitllent Percent by Weight SiO2 69.0 2 3 4.5 CaO 9.0 MgO 3.9 K2O - 1.1 Na2O 12.3 10Group II (volatile constituents~
Constituents Percent by Weight Na2O 32~0 2 3 67.0 -The group I composition is identifiable as a soda lime silica glass closely resembling plate glass compositions which although fiberizable is unsuitable as an insulating wool. How-ever, it is~less hostile to prepare than the insulating wool glass composition given above. The group II composition, how-ever, is highly volatile and corrosive. Therefore, the group I
constltuents are prepared as a molten base glass composition in a continuous glass melting unit common to the glass-making industry. The sodium borate constituents of group II are then introduced into the molten base glass composition of group I
either as a melt or raw batch formulation.
Since the volatile constituents of group II represent only 11% by weight of the total glass composition, they may be melted in a significantly smaller melting unit and at a substan-tially lower operating temperature. Thus, there will be less sodium borate loss by volatilization simplifying the task of pollutant elimination.
,. -.: . . .. .. .
Further, since the soda lime silica glass of group I is ~ - approximately half as corrosive as the insulating wool glass composition, one may expect a 100% increase in melter refractory :
life.
By way of further example, a common fiberizable glass composition for glass fiber textile production is:
Constituent Percent by Weight ~.
Si2 55.0 A123 15.0 :
CaO 22.0 .
2 3 7.0 F2 0.5 ~:
0.5 :
The volatile constituents of concern within this molten glass composition are B2O3, F2 and Na2O. Therefore, similar to ~ , the wool glass example above, two melting groups may be identi- ~:
fied as follows:
Group I (non-volatile constituents) Constituent Percent by Weight ~ ;
SiO2 60.0 A123 16.3 ~-CaO 23.7 Group II (volatile constituents) Constituent Percent by Weight B2O3 87.5 .
F2 6.25 Na2O 6.25 By the above grouping the hignly volatile constituents of group II, representing 8% by weight of the desired fiberizable -molten glass composition, may be separately prepared in a rela-. , ~ . .. ,, . ,.. . -. ~ . . . , . - .. . -. ,.: , ,.. ;.: . . .-, , . ., :: , . - ::
106~307 tively small melter and added to the molten base glass composi-tion realizing similar benefits as in preparation of the wool glass composition. However, further advantages are possible by reformulating the molten base glass composition of group I to obtain a eutectic composition in the CaO - Al2O3 - SiO2 system as follows:
Constituent- Percent by Weight SiO2 62.0 2 3 15.0 CaO 23.0 ~ ;
Adding the remnant constituents to the group II composi-tion it now becomes:
ConstituentPercent by Weight SiO2 13.0 CaO 12.9 A123 12.3 2 3 54.0 F2 3.9 Na2O 3.9 Thus, by selective grouping of the textile molten glass constituents we obtain a eutectic base glass composition, there-by lowering the main melter operating temperature. Further, this formulation allows the use of less expensive raw materials, such ascolemanite, as a partial source of B2O3, reducing the need for more expensive boric acid.
Accompanying Figs. l to 5 presentpreferred apparatus for introducing the molten additive composition into the molten base `
glass and homogenizing the mixture to obtain the final desired molten glass composition. In the drawings:
Figure l shows a typical glass fiber-forming operation embodying (~ ~
106i9307 ;
the present invention;
Figure 2 is a pictorial view showing the general configuration of preferred forehearth mixing apparatus for practising the invention;
Figure 3 is a schematic plan view of the forehearth mixing apparatus; -~
; Figure 4 presents a side elevation taken along line 4-4 of Figure
3 showing the molten glass flow pattern; and Figure 5 presents an end elevation taken along line 5-5 of Figure 3 looking upstream in the forehearth.
Figure 1 illustrates typical apparatus for producing glass fibers embodying the present invention. A continuous elec-tric glass melter 10 is charged with the base glass batch formu-lation by traversing hopper 11. Molten base glass is withdrawn ~-from melter 10 and flowed through forehearth 12. Positioned downstream of melter 10 within forehearth 12 is a molten glass mixing zone indicated by spiral stirrers 15 and 16. A more detailed description of the mixing zone and function of the stir- -.
rers is presented below. The molten additive composition is pre-20- pared in separate melting apparatus 20 and introduced to the , mixing zone through a suitable conduit 21. By a combined mixing r~ and pumping action of stirrers 15 and 16 the molten additive com-position is mixed into and homogenized with the molten base glass composition forming the final molten glass composition. The final molten glass composition is then conveyed through distri- -bution forehearth 17 to glass fiber-forming positions 22 and 23.
Figure 2 presents a pictorial view of the forehearth mixing zone with stirrers 15 and 16 not being shown so that the configuration and orientation of stirrer mixing blocks 13 and 14 may be viewed more clearly. The general flow of molten glass is ~
.
~,f ~069307 from the upper left of Figure 2 to the lower right as indicated by arrow 30. Mixing blocks 13 and 14 are identical structures;
the only difference being their general orientation within the forehearth channel. Therefore, to avoid redundant discussion the structure of block 13 will be described with the understand-ing that block 14 is the same except for orientation and func-tion as described.
Block 13 extends across the forehearth channel with its upstream face 31 acting as a barrier or dam to the flow of molten base glass. Cylindrical stirrer well 33 extends downward from the top surface 32 of block 13 communicating with slot 34 which, in combination with the forehearth channel floor, forms a rectangular passage extending longitudinally within the fore-hearth channel exiting at the block downstream face 35.
Mixing block 14, similar in configuration to block 13, is positioned downstream of block 13 with its slot 34a facing upstream and opposite slot 34 of block 13. Extending between mixing blocks 13 and 14 are key blocks 361 and 36r having respective angular faces 371 and 37r slanting from the forehearth ~side walls to the forqhearth floor thereby forming in combina-.
tion with the forehearth floor a flow channel communicating between slot 34 of block 13 and slot 34a of block 14.
Figures 3 and 4 present a plan and a side cross-section-al elevation view, respectively, of mixing blocks 13 and 14 with screw-type stirrers 43 and 44 positioned therein. Stirrers 43 and 44 comprise a spiral blade wrapped about a central shaft rotatably powered, as indicated by the arrows in Figure 3, by any preferred means such as a geared electric motor (not shown).
Upstream mixing block 13 acts as a dam to the flowing molten base glass composition causing the base glass to flow over the top of ~ .
the block and into the region of influence of the stirrer 43.
Immediately upstream of stirrer 43, the molten additive composi-tion is introduced to the flowing base glass composition, through conduit 21, as it flows over the upstream portion of mixing block 13. The molten additive is preferably introduced below the sur-face of the flowing base glass composition as shown.
Stirrer 43 mixes the molten base glass and molten addi-tive while pumping the mixture downward through mixing block 13 causing it to exit in a downstream direction from slot 34. Key blocks 361 and 36r channel a major portion of the exiting mixture to slot 34a of block 14 which acts as an intake port for block 14. As indicated by arrow 45 in Figure 4 a portion of the molten mixture exiting from slot 34 flows upward and is drawn back into mixing block 13 and thereby recycled through stirrer 43. The portion of molten mixture channeled to slot 34a is then further mixed while being pumped upward through block 14, by action of stirrer 44. Exiting at and flowing over the top surface of block 14 is the final molten glass composition. A portion of the molten glass exiting the top of block 14 flows upstream, a - ~
major portion of which, indicated by arrow 46, is returned to the intake port 34a of block 14 and recycled; the lesser portion continues upstream, as indicated by arrow 48, and is recycled through mixing block 13. The remaining molten composition indicated by arrow 47 flows downstream to distribution forehearth 17. The reverse flow patterns, indicated by arrows 45, 46 and 48, cause the natural occurrence of a fluidic front or dam to be established atop mixing block 13 as indicated by line 50.
Upstream of fluidic front 50 is virgin base glass. Thus, the presence of fluidic front 50 directs the flow of unmixed molten base blass through mixing block 13 preventing fluidic short circuiting. Alternatively, a structural dam may be constructed atop block 13 thereby assuring the flow of unmixed base glass through block 13.
By practising the present method of preparing molten glass compositions a new freedom of glass formulating is avail-able. Not only may specific base glasses be formulated to im-prove the over-all economics of the glass-making process but highly volatile constituents, such as water, may now be formu-lated into the molten glass composition.
In conclusion, it is pointed out that while the illus-trative examples constitute practical embodiments of the inven-tion, it is not intended to limit the invsntion to the exact details shown since modifications may be made without departing from the spirit and scope of the invention disclosed.
-C
Figure 1 illustrates typical apparatus for producing glass fibers embodying the present invention. A continuous elec-tric glass melter 10 is charged with the base glass batch formu-lation by traversing hopper 11. Molten base glass is withdrawn ~-from melter 10 and flowed through forehearth 12. Positioned downstream of melter 10 within forehearth 12 is a molten glass mixing zone indicated by spiral stirrers 15 and 16. A more detailed description of the mixing zone and function of the stir- -.
rers is presented below. The molten additive composition is pre-20- pared in separate melting apparatus 20 and introduced to the , mixing zone through a suitable conduit 21. By a combined mixing r~ and pumping action of stirrers 15 and 16 the molten additive com-position is mixed into and homogenized with the molten base glass composition forming the final molten glass composition. The final molten glass composition is then conveyed through distri- -bution forehearth 17 to glass fiber-forming positions 22 and 23.
Figure 2 presents a pictorial view of the forehearth mixing zone with stirrers 15 and 16 not being shown so that the configuration and orientation of stirrer mixing blocks 13 and 14 may be viewed more clearly. The general flow of molten glass is ~
.
~,f ~069307 from the upper left of Figure 2 to the lower right as indicated by arrow 30. Mixing blocks 13 and 14 are identical structures;
the only difference being their general orientation within the forehearth channel. Therefore, to avoid redundant discussion the structure of block 13 will be described with the understand-ing that block 14 is the same except for orientation and func-tion as described.
Block 13 extends across the forehearth channel with its upstream face 31 acting as a barrier or dam to the flow of molten base glass. Cylindrical stirrer well 33 extends downward from the top surface 32 of block 13 communicating with slot 34 which, in combination with the forehearth channel floor, forms a rectangular passage extending longitudinally within the fore-hearth channel exiting at the block downstream face 35.
Mixing block 14, similar in configuration to block 13, is positioned downstream of block 13 with its slot 34a facing upstream and opposite slot 34 of block 13. Extending between mixing blocks 13 and 14 are key blocks 361 and 36r having respective angular faces 371 and 37r slanting from the forehearth ~side walls to the forqhearth floor thereby forming in combina-.
tion with the forehearth floor a flow channel communicating between slot 34 of block 13 and slot 34a of block 14.
Figures 3 and 4 present a plan and a side cross-section-al elevation view, respectively, of mixing blocks 13 and 14 with screw-type stirrers 43 and 44 positioned therein. Stirrers 43 and 44 comprise a spiral blade wrapped about a central shaft rotatably powered, as indicated by the arrows in Figure 3, by any preferred means such as a geared electric motor (not shown).
Upstream mixing block 13 acts as a dam to the flowing molten base glass composition causing the base glass to flow over the top of ~ .
the block and into the region of influence of the stirrer 43.
Immediately upstream of stirrer 43, the molten additive composi-tion is introduced to the flowing base glass composition, through conduit 21, as it flows over the upstream portion of mixing block 13. The molten additive is preferably introduced below the sur-face of the flowing base glass composition as shown.
Stirrer 43 mixes the molten base glass and molten addi-tive while pumping the mixture downward through mixing block 13 causing it to exit in a downstream direction from slot 34. Key blocks 361 and 36r channel a major portion of the exiting mixture to slot 34a of block 14 which acts as an intake port for block 14. As indicated by arrow 45 in Figure 4 a portion of the molten mixture exiting from slot 34 flows upward and is drawn back into mixing block 13 and thereby recycled through stirrer 43. The portion of molten mixture channeled to slot 34a is then further mixed while being pumped upward through block 14, by action of stirrer 44. Exiting at and flowing over the top surface of block 14 is the final molten glass composition. A portion of the molten glass exiting the top of block 14 flows upstream, a - ~
major portion of which, indicated by arrow 46, is returned to the intake port 34a of block 14 and recycled; the lesser portion continues upstream, as indicated by arrow 48, and is recycled through mixing block 13. The remaining molten composition indicated by arrow 47 flows downstream to distribution forehearth 17. The reverse flow patterns, indicated by arrows 45, 46 and 48, cause the natural occurrence of a fluidic front or dam to be established atop mixing block 13 as indicated by line 50.
Upstream of fluidic front 50 is virgin base glass. Thus, the presence of fluidic front 50 directs the flow of unmixed molten base blass through mixing block 13 preventing fluidic short circuiting. Alternatively, a structural dam may be constructed atop block 13 thereby assuring the flow of unmixed base glass through block 13.
By practising the present method of preparing molten glass compositions a new freedom of glass formulating is avail-able. Not only may specific base glasses be formulated to im-prove the over-all economics of the glass-making process but highly volatile constituents, such as water, may now be formu-lated into the molten glass composition.
In conclusion, it is pointed out that while the illus-trative examples constitute practical embodiments of the inven-tion, it is not intended to limit the invsntion to the exact details shown since modifications may be made without departing from the spirit and scope of the invention disclosed.
-C
Claims (14)
1. A method of producing a borosilicate glass, which method includes the steps of:
(a) melting a base portion of the glass composition free of at least a major portion of the boric oxide yielding ingredients;
(b) introducing as an additive portion the remainder of the glass composition including the boric oxide yielding ingredients; and (c) mixing and homogenizing said additive portion with the molten base glass in proportions to form the borosilicate glass of desired composition.
(a) melting a base portion of the glass composition free of at least a major portion of the boric oxide yielding ingredients;
(b) introducing as an additive portion the remainder of the glass composition including the boric oxide yielding ingredients; and (c) mixing and homogenizing said additive portion with the molten base glass in proportions to form the borosilicate glass of desired composition.
2. A method of forming borosilicate glass which in-cludes the steps of:
(a) separating the batch formulation into ingredients for forming a base glass portion free of at least a major portion of the boric oxide yielding ingredients and an additive portion con-taining the desired amount of boric oxide yielding ingredients;
(b) melting said base glass portion to form a molten mass;
(c) introducing said additive portion into said molten mass; and (d) mixing and homogenizing said additive portion with said molten mass in such proportions as to form a borosilicate glass of desired composition.
(a) separating the batch formulation into ingredients for forming a base glass portion free of at least a major portion of the boric oxide yielding ingredients and an additive portion con-taining the desired amount of boric oxide yielding ingredients;
(b) melting said base glass portion to form a molten mass;
(c) introducing said additive portion into said molten mass; and (d) mixing and homogenizing said additive portion with said molten mass in such proportions as to form a borosilicate glass of desired composition.
3. The method as defined in claim 1 or 2, wherein said additive portion containing the boric oxide yielding in-gredients is separately prepared as a melt, and then is intro-duced into said molten base glass mass in the melt phase.
4. A method of producing a borosilicate glass of desired composition, which method achieves a material reduction in volatilization of B2O3 and includes the steps of:
(a) preparing a molten base glass composition substantially free of B2O3;
(b) melting said base glass composition in a melter and flowing the same through an outlet zone;
(c) melting in a separate chamber an additive glass composition containing sufficient B2O3 to substantially change the forming characteristics of said base glass composition to a glass com-position which can be formed into a borosilicate glass product of desired composition;
(d) introducing said molten additive glass composition into said molten base glass composition; and (e) mixing and homogenizing said additive glass composition throughout the molten base glass composition to produce the borosilicate glass of desired composition.
(a) preparing a molten base glass composition substantially free of B2O3;
(b) melting said base glass composition in a melter and flowing the same through an outlet zone;
(c) melting in a separate chamber an additive glass composition containing sufficient B2O3 to substantially change the forming characteristics of said base glass composition to a glass com-position which can be formed into a borosilicate glass product of desired composition;
(d) introducing said molten additive glass composition into said molten base glass composition; and (e) mixing and homogenizing said additive glass composition throughout the molten base glass composition to produce the borosilicate glass of desired composition.
5. A method of producing borosilicate glass and re-ducing effluent to the atmosphere from the volatile bearing constituents in the formulation, which method includes the steps of:
(a) preparing a molten base glass composition containing a major portion of silica and modifiers in the absence of major portions of effluent materials B2O3 and F2;
(b) flowing said base glass composition from a melter into a forehearth channel;
(c) melting in a separate chamber an additive glass composition including effluent bearing constituents B2O3 and F2 in sufficient quantities such that when the additive glass composition is added to the base glass composition it will materially change the forming characteristics thereof and produce a borosilicate glass containing B2O3; and (d) mixing and homogenizing said additive glass composition throughout the molten base glass composition to produce a glass having the desired forming characteristics.
(a) preparing a molten base glass composition containing a major portion of silica and modifiers in the absence of major portions of effluent materials B2O3 and F2;
(b) flowing said base glass composition from a melter into a forehearth channel;
(c) melting in a separate chamber an additive glass composition including effluent bearing constituents B2O3 and F2 in sufficient quantities such that when the additive glass composition is added to the base glass composition it will materially change the forming characteristics thereof and produce a borosilicate glass containing B2O3; and (d) mixing and homogenizing said additive glass composition throughout the molten base glass composition to produce a glass having the desired forming characteristics.
6. The method as defined in claim 5, in which said molten additive glass composition is combined with said molten base glass composition by mechanical stirring.
7. A method of forming a fiberizable borosilicate glass, which method includes the steps of:
(a) separating batch ingredients for said glass into ingredients for forming a host glass and for forming a B2O3-containing additive glass;
(b) melting said ingredients for forming said host glass in a generally horizontally-disposed, continuous flow, main-melter;
(c) flowing said molten host glass from said main melter to a location where glass fibers are formed;
(d) separately melting said additive glass and homogenizing, with forceful mechanical mixing, said moletn additive glass with a larger portion of said molten host glass prior to said fiber-forming location to form a fiberizable borosilicate glass; and (e) forming borosilicate glass fiber at said fiber-forming location from said fiberizable glass;
whereby at least a major proportion of the B2O3 content of said fiber is supplied by said additive glass, said melter exhibits longer life, and the volatilization losses of B2O3 are substan-tially less than that which results when melting the ingredients of said additive glass and host glass together in said melter.
(a) separating batch ingredients for said glass into ingredients for forming a host glass and for forming a B2O3-containing additive glass;
(b) melting said ingredients for forming said host glass in a generally horizontally-disposed, continuous flow, main-melter;
(c) flowing said molten host glass from said main melter to a location where glass fibers are formed;
(d) separately melting said additive glass and homogenizing, with forceful mechanical mixing, said moletn additive glass with a larger portion of said molten host glass prior to said fiber-forming location to form a fiberizable borosilicate glass; and (e) forming borosilicate glass fiber at said fiber-forming location from said fiberizable glass;
whereby at least a major proportion of the B2O3 content of said fiber is supplied by said additive glass, said melter exhibits longer life, and the volatilization losses of B2O3 are substan-tially less than that which results when melting the ingredients of said additive glass and host glass together in said melter.
8. The method as defined in claim 7, wherein substan-tially all the B2O3 of said fiber is supplied by said additive glass.
9. The method as defined in claim 7 or 8, wherein said fiber includes fluorine, substantially all of which is supplied by said additive glass.
10. The method as defined in claim 7 or 8, wherein said host glass has a higher liquidus temperature than said additive glass.
11. The method as defined in claim 7 or 8, wherein the composition of said host glass is such that its viscosity and/or liquidus temperature are unsuitable for practicable forming and said additive glass is added in an amount so that the combined glass is suitable for practicable forming.
12. The method as defined in claim 7, wherein the ingredients of the host glass comprise (balance-minor impurities):
Percent by Weight SiO2 69.0 A12O3 4.5 CaO 9.0 MgO 3.9 K20 1.1 Na20 12.3 and the ingredients of the additive glass comprise (balance-minor impurities):
Percent by Weight Na2O 32.0 B2O3 67.0
Percent by Weight SiO2 69.0 A12O3 4.5 CaO 9.0 MgO 3.9 K20 1.1 Na20 12.3 and the ingredients of the additive glass comprise (balance-minor impurities):
Percent by Weight Na2O 32.0 B2O3 67.0
13. The method as defined in claim 7, wherein the host glass ingredients comprise:
Percent by Weight SiO2 60.0 A12O3 16.3 CaO 23.7 and the additive glass ingredients comprise:
Percent by Weight B2O3 87.5 F2 6.25 Na2O 6.25
Percent by Weight SiO2 60.0 A12O3 16.3 CaO 23.7 and the additive glass ingredients comprise:
Percent by Weight B2O3 87.5 F2 6.25 Na2O 6.25
14. The method as defined in claim 7, wherein the host glass ingredients comprise:
Percent by Weight SiO2 62.0 A12O3 15.0 CaO 23.0 and the additive glass ingredients comprise:
Percent by Weight SiO2 13.0 CaO 12.9 A12O3 12.3 B2O3 54.0 F2 3.9 Na2O 3.9
Percent by Weight SiO2 62.0 A12O3 15.0 CaO 23.0 and the additive glass ingredients comprise:
Percent by Weight SiO2 13.0 CaO 12.9 A12O3 12.3 B2O3 54.0 F2 3.9 Na2O 3.9
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52687674A | 1974-11-25 | 1974-11-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069307A true CA1069307A (en) | 1980-01-08 |
Family
ID=24099180
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA239,554A Expired CA1069307A (en) | 1974-11-25 | 1975-11-13 | Method of making glass |
Country Status (20)
| Country | Link |
|---|---|
| JP (1) | JPS5230815A (en) |
| AR (1) | AR208732A1 (en) |
| AU (1) | AU499562B2 (en) |
| BE (1) | BE835871A (en) |
| BR (1) | BR7507740A (en) |
| CA (1) | CA1069307A (en) |
| DD (1) | DD123080A5 (en) |
| DE (1) | DE2552116C3 (en) |
| DK (1) | DK530175A (en) |
| ES (1) | ES442924A1 (en) |
| FI (1) | FI753306A (en) |
| FR (1) | FR2291947A1 (en) |
| GB (1) | GB1508167A (en) |
| IL (1) | IL48480A0 (en) |
| IT (1) | IT1049921B (en) |
| NL (1) | NL7513769A (en) |
| NO (1) | NO753958L (en) |
| SE (1) | SE7513048L (en) |
| TR (1) | TR19059A (en) |
| ZA (1) | ZA757110B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4696691A (en) * | 1986-10-02 | 1987-09-29 | Ppg Industries, Inc. | Method of glass batch preheating and liquefying with recycling of particulates |
| FR2851767B1 (en) * | 2003-02-27 | 2007-02-09 | Saint Gobain | PROCESS FOR PREPARING A GLASS BY MIXING FOUNDED GLASSES |
| DE102005050871B4 (en) * | 2005-10-24 | 2007-02-08 | Beteiligungen Sorg Gmbh & Co. Kg | Method and device for conditioning and homogenizing molten glass |
| JP4908157B2 (en) * | 2006-11-13 | 2012-04-04 | 田中貴金属工業株式会社 | Molten glass stirring rod and molten glass stirring device including the molten glass stirring rod |
| DE102007038211A1 (en) * | 2007-08-13 | 2009-02-19 | Diether Böttger | Device for homogenizing molten glass for the production of flat glass e.g. glass substrates for flat screen, comprises a supply distributor, heated mixer cells and a discharge distributor |
| CN114835380B (en) * | 2022-04-07 | 2023-08-25 | 齐鲁工业大学 | Melting production process for inhibiting volatilization of borosilicate glass components |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL132721C (en) * | 1965-04-19 |
-
1975
- 1975-11-12 ZA ZA757110A patent/ZA757110B/en unknown
- 1975-11-13 CA CA239,554A patent/CA1069307A/en not_active Expired
- 1975-11-13 GB GB46912/75A patent/GB1508167A/en not_active Expired
- 1975-11-14 IL IL48480A patent/IL48480A0/en unknown
- 1975-11-18 AU AU86712/75A patent/AU499562B2/en not_active Expired
- 1975-11-20 SE SE7513048A patent/SE7513048L/en unknown
- 1975-11-20 DE DE2552116A patent/DE2552116C3/en not_active Expired
- 1975-11-24 FI FI753306A patent/FI753306A/fi not_active Application Discontinuation
- 1975-11-24 IT IT29592/75A patent/IT1049921B/en active
- 1975-11-24 AR AR261326A patent/AR208732A1/en active
- 1975-11-24 BR BR7507740*A patent/BR7507740A/en unknown
- 1975-11-24 NO NO753958A patent/NO753958L/no unknown
- 1975-11-24 BE BE162124A patent/BE835871A/en unknown
- 1975-11-24 FR FR7535821A patent/FR2291947A1/en not_active Withdrawn
- 1975-11-25 DD DD189684A patent/DD123080A5/xx unknown
- 1975-11-25 TR TR19059A patent/TR19059A/en unknown
- 1975-11-25 NL NL7513769A patent/NL7513769A/en not_active Application Discontinuation
- 1975-11-25 JP JP50141086A patent/JPS5230815A/en active Pending
- 1975-11-25 DK DK530175A patent/DK530175A/en unknown
-
1977
- 1977-04-13 ES ES442924A patent/ES442924A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NO753958L (en) | 1976-05-26 |
| IT1049921B (en) | 1981-02-10 |
| NL7513769A (en) | 1976-05-28 |
| ES442924A1 (en) | 1977-08-01 |
| DE2552116C3 (en) | 1980-01-17 |
| TR19059A (en) | 1978-04-12 |
| DK530175A (en) | 1976-05-26 |
| AR208732A1 (en) | 1977-02-28 |
| ZA757110B (en) | 1977-06-29 |
| BR7507740A (en) | 1976-08-10 |
| DE2552116B2 (en) | 1979-05-31 |
| IL48480A0 (en) | 1976-01-30 |
| DE2552116A1 (en) | 1976-05-26 |
| JPS5230815A (en) | 1977-03-08 |
| AU499562B2 (en) | 1979-04-26 |
| FR2291947A1 (en) | 1976-06-18 |
| DD123080A5 (en) | 1976-11-20 |
| AU8671275A (en) | 1977-05-26 |
| SE7513048L (en) | 1976-05-26 |
| FI753306A (en) | 1976-05-26 |
| BE835871A (en) | 1976-05-24 |
| GB1508167A (en) | 1978-04-19 |
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