US20040206126A1 - Method and apparatus for oxygen refinement of a glass melt - Google Patents
Method and apparatus for oxygen refinement of a glass melt Download PDFInfo
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- US20040206126A1 US20040206126A1 US10/845,944 US84594404A US2004206126A1 US 20040206126 A1 US20040206126 A1 US 20040206126A1 US 84594404 A US84594404 A US 84594404A US 2004206126 A1 US2004206126 A1 US 2004206126A1
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- glass
- glass melt
- oxygen
- melt
- noble metal
- 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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- 239000000156 glass melt Substances 0.000 title claims abstract description 56
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 239000001301 oxygen Substances 0.000 title claims abstract description 50
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims description 45
- 239000011521 glass Substances 0.000 claims abstract description 43
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 38
- 238000007670 refining Methods 0.000 claims abstract description 37
- 239000007789 gas Substances 0.000 claims description 40
- 239000000203 mixture Substances 0.000 claims description 5
- 238000010411 cooking Methods 0.000 claims description 4
- 238000010907 mechanical stirring Methods 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 claims description 3
- 239000004973 liquid crystal related substance Substances 0.000 claims description 2
- 239000010409 thin film Substances 0.000 claims description 2
- 239000005357 flat glass Substances 0.000 claims 1
- 239000000155 melt Substances 0.000 abstract description 28
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 22
- 230000008569 process Effects 0.000 description 12
- 239000007788 liquid Substances 0.000 description 11
- 239000001257 hydrogen Substances 0.000 description 10
- 229910052739 hydrogen Inorganic materials 0.000 description 10
- 238000002844 melting Methods 0.000 description 10
- 230000008018 melting Effects 0.000 description 10
- 229910052697 platinum Inorganic materials 0.000 description 10
- 239000000126 substance Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000000523 sample Substances 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 6
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 229910001882 dioxygen Inorganic materials 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 4
- 238000010309 melting process Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 150000002431 hydrogen Chemical class 0.000 description 3
- 231100000614 poison Toxicity 0.000 description 3
- 230000007096 poisonous effect Effects 0.000 description 3
- 230000001603 reducing effect Effects 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910000410 antimony oxide Inorganic materials 0.000 description 2
- 229910000413 arsenic oxide Inorganic materials 0.000 description 2
- 229960002594 arsenic trioxide Drugs 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- KTTMEOWBIWLMSE-UHFFFAOYSA-N diarsenic trioxide Chemical compound O1[As](O2)O[As]3O[As]1O[As]2O3 KTTMEOWBIWLMSE-UHFFFAOYSA-N 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000004579 marble Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- VTRUBDSFZJNXHI-UHFFFAOYSA-N oxoantimony Chemical compound [Sb]=O VTRUBDSFZJNXHI-UHFFFAOYSA-N 0.000 description 2
- 239000005365 phosphate glass Substances 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 229910001260 Pt alloy Inorganic materials 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000007496 glass forming Methods 0.000 description 1
- 239000002241 glass-ceramic Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010128 melt processing Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- -1 platinum group metals Chemical class 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000010671 solid-state reaction Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- 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
- C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
- C03C1/004—Refining agents
-
- 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
- C03B5/18—Stirring devices; Homogenisation
- C03B5/193—Stirring devices; Homogenisation using gas, e.g. bubblers
-
- 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
- C03B5/225—Refining
Definitions
- the present invention relates to methods and processes for oxygen refinement of water and/or liquids containing hydroxyl groups, especially glass melts, to an apparatus for performing these methods and to glass obtained using these methods as part of the glass production process.
- the resulting melt is thus designated a raw melt.
- it has very distinct streaking or regions of varying index of refraction and many bubbles, which impair the quality of a glass and/or glass-ceramic body that is made from the glass melt. Because of this reason the still strongly streaked and bubble containing glass melt is heated further and homogenized by means of mechanical stirring elements, by chopping with fine needles or by blowing oxygen into it through fine nozzles. These methods refine the glass melt of the gas bubbles.
- refinement or “refining” of the glass means a melting process comprising sequential melting process steps performed in so-called refining chambers, which
- [0014] is to be integrated in a complex sequence of melt processing steps.
- the chemical refinement also comprises a sequence of elementary steps interlaced with each other spatially and temporally.
- the refining bubbles extract gas dissolved in the glass.
- Color, moisture content and the so-called reboil conditions for O 2 and SO 2 are the targeted parameters for a successful adjustment of the gas content of the glass. Once a satisfactory bubble quality is obtained it is not impaired in subsequent cool-down or casting processes.
- Chemical refinement has several principal disadvantages. First the methods. First these methods do not function well for every glass system, especially during NaCl refinement, or only at higher temperature, which also requires much time, since gas diffusion in the melt takes too long. Thus the refining chambers must be comparatively large, which further increases product costs. Finally the chemical refining agents change the chemistry of the glass and thus its properties. Moreover arsenic oxide is extremely poisonous and the required purity is not reached without more work. Major environmental problems are also connected both with its manufacture and its use. They also occur for antimony oxide. Cerium oxide itself is of course not poisonous, but it is extremely expensive so that its use is limited to specialty glass.
- DE-A 3 022 091 described an apparatus for melting glass in a melt oven with a refining device for refinement of the glass and at least one receiver in which a direct current is applied to a heated electrode formerly or usually operated with alternating current.
- a method and apparatus for melting of those glasses which have a high reducing action in a melted state are described in DE-A 3 906 270.
- phosphate glass whose reducing action is even more pronounced in the melted state, erosion by immersion of platinum parts should be avoided.
- the reducing action of phosphate glass is so great that the glass reacts with platinum or a platinum alloy of the melt-containing vessel to form a platinum-phosphorous alloy.
- This platinum-phosphorous alloy however has a melting point of 588° C., which is below the glass melt temperature. This alloy is dissolved in the melt, which leads to the dissolving of the platinum glass melt-containing vessel. This is also the situation for platinum stirring tools or elements.
- U.S. Pat. No. 5,785,726 describes a method of making glasses for flat display screens, especially LCDs (Liquid Crystal Displays) and TFTs (Thin Film Transistors).
- LCDs Liquid Crystal Displays
- TFTs Thin Film Transistors
- Glass of higher purity may thus be prepared according to the methods of the invention, which is free of gas inclusion and free of additional impurities introduced by the refinement.
- the method according to the invention is also suitable for removal of water residues and/or hydroxyl residues.
- this method is very well controlled by adjusting the oxygen content and/or partial pressure of oxygen in the gas flow.
- the method is appropriately not limited to a definite temperature as is required in many chemical and other physical refining processes.
- the noble metals which are suitable for use in this method are principally all those noble metals, which are particularly hydrogen permeable at the conditions occurring in the glass melt, i.e. those which have a high hydrogen diffusion coefficient. Platinum and all metals belonging to the platinum group metals, gold, rhenium or alloys thereof, are suitable. According to the invention other materials may be used for the noble metal member, which are stable at the process temperatures and which have a bridge or portion of the foregoing of noble metals. The bridge or portion of the noble metals must extend between the outside surface or outer side facing the glass melt and the inner or interior side of the noble metal member. This type of bridge can be a network or a number of fibers. A platinum vessel and/or platinum dish can be used as the noble metal member.
- a noble metal pipe is arranged, especially in the region in which the refining step occurs.
- the pipe runs to the vessel bottom.
- This sort of pipe appropriately has a meandering shape, which preferably passes through the entire refining region. It some cases it has proven to be sufficient when the oxygen-rinsed noble metal pipe is installed at a single place in the refining region.
- the oxygen-rinsed noble metal pipe is a U-shaped pipe, which is arranged in the melt so that it is either dipped in the melt from above or is guided through the melt from below. In both cases the horizontal portion of the U-shaped pipe extends along the vessel bottom or is spaced a short distance from it.
- the noble metal member includes a stirrer rinsable with oxygen gas.
- the advantageous features may be combined with each other, which produce mechanical stirring of the melt and thorough mixing. This leads to a particularly efficient homogenizing and refining.
- Air and oxygen-containing waste air from process gas such as exhaust gas from combustion, especially from gas and oil burners.
- process gas such as exhaust gas from combustion, especially from gas and oil burners.
- pure oxygen in the method according to the invention.
- the oxygen input is controlled by means of a control element.
- a control element such as the probe described by Frey, Schaeffer and Baucke in Glasstechn. Ber. [Glass Engineering Report] 53, pp. 116-123 (1980).
- the oxygen input to the noble metal member can be exactly controlled by means of a control device responding to the measured values from the probe. Since other gases, such as CO 2 or also SO 2 , are also removed by the oxygen refining, the oxygen input can also be controlled by a suitable SO 2 - or CO 2 -probe.
- the oxygen introduced into the glass melt by the refining process according to the invention is removed in a process step occurring after the refining. This can occurs for example by working at low pressure besides the known physical methods.
- the dissolved oxygen and/or the minute, frequently invisible gas bubbles still present expand under a low pressure, so that they rapidly rise to the surface of the melt.
- the melt is acted on by pressure in this process step so that a so-called “forcing off” of the bubble formation occurs.
- an additional hydrogen permeable noble metal member in the melt and to act on it with hydrogen, hydrogen-containing gas or gases and/or vapors, which split off hydrogen at higher temperatures, such as water and/or ammonia.
- hydrogen, hydrogen-containing gas or gases and/or vapors which split off hydrogen at higher temperatures, such as water and/or ammonia.
- oxygen still present in the melt is reduced to water and/or to hydroxyl groups, which are dissolved in the glass melt and in the finished glass.
- the oxygen is preferably removed in the cool-down region.
- the additional noble metal member can be formed, as a whole, like the noble metal member described above for generating oxygen in the melt.
- the so-called feeder trough is an additional preferred location for removal of oxygen from the glass melt.
- the invention also includes an apparatus for performing the foregoing method.
- the apparatus according to the invention includes a region, in which the liquid, especially the glass melt, is in contact with a noble metal member.
- the noble metal member has one side facing the liquid and/or glass melt and another side acted on with the oxygen that is facing away from the liquid and/or glass melt.
- this noble metal member is the vessel base or bottom, in which the glass melt is refined.
- the noble metal member is a mechanical stirrer, whose interior side can be rinsed with the oxygen gas.
- the glasses obtained by the method according to the invention are especially suitable for making electronic tubes, such as display screens, especially televisions and computer monitors, as well as flat screen devices, such as LCDs and TFTs. Also the glasses obtained by the method according to the invention are especially suitable for optical lenses and units and devices containing them. Lamp glass and glass for light sources are also suitable applications. The glasses obtained by the method according to the invention are also suitable for making cooking panels for hearth, such as Ceran® panel, and for cooking-ware (Jenaerglass®) and for microwave cooking units.
- FIGURE is a flow chart for the method of refining a glass melt according to the invention.
- the sole FIGURE shows a glass melt vessel 10 , in which the minerals used to make glass, such as quartz, soda, lime, marble, etc, are supplied in a finely divided or ground heap. Following that these solids are melted in a melting region 20 and then flow further into the refining region 30 of the vessel 10 .
- a noble metal pipe 40 which includes an oxygen inlet section 42 and an oxygen outlet section 44 , is arranged in the refining region 30 at the bottom of the vessel 10 .
- the oxygen inlet section 42 is controlled by means of a first control device 50 , which receives control signals from a first oxygen probe 60 immersed or dipped in the refining region 30 .
- German Patent Application 100 09 425.2 of Feb. 28, 2000 is incorporated here by reference.
- This German Patent Application describes the invention described hereinabove and claimed in the claims appended hereinbelow and provides the basis for a claim of priority for the instant invention under 35 U.S.C. 119.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Glass Compositions (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
An apparatus for making glass in which a glass melt is refined in a vessel with oxygen is described. It includes a melt-containing vessel (10) having a refining region (3) for refinement of the glass melt and a noble metal member for producing oxygen in the melt. The noble metal member (40) has an outer side facing the glass melt and an inner side facing away from the glass melt washed with and acted on with oxygen. Oxygen-containing bubbles are vigorously generated on the outer side of the noble metal member facing the glass melt when the inner side is washed with the oxygen.
Description
- 1. Field of the Invention
- The present invention relates to methods and processes for oxygen refinement of water and/or liquids containing hydroxyl groups, especially glass melts, to an apparatus for performing these methods and to glass obtained using these methods as part of the glass production process.
- Liquids, in which gases are dissolved, which in part form bubbles in the liquid, participate in many technical production processes. Since these gases or gas bubbles interfere with further processing and/or disadvantageously impair the properties and thus the quality of the product, it is necessary to free the liquid of these bubbles. This process is called bubble removal or refinement.
- In the following the problems of refinement of liquids are described using the example of refinement of a glass melt, but the invention should not be considered as limited to this example. The same problem is present in other applications.
- 2. Prior Art
- During manufacture of glass from inorganic material raw materials and of course silica or glass sand, soda, limestone, marble or calcereous clay, are mixed and melted in a continuously running process. The melting process takes place in different stages, in which chemical reactions and physical processes occur side-by-side. At higher temperatures solid state reactions occur at the points of contact between neighboring grains. Moreover CO2 and H2O are released from the crystalline phase. The CO2 is generated by decomposition of the glass-forming salts. In so far as sulfates are present also SO2 is released.
- As a result of the decomposition of the starting materials present in the reaction mixture a considerable quantity of gas is generated during melting of glass. As a rough estimate, it is said that about 1 kg of glass results from melting 1.2 kg of the mixture, i.e. about ⅕ of the mixture weight is released in the form of gas during the melting. Furthermore also other gases are conducted through the mixture during the melting or introduced into the melting glass by the combustion oven.
- The release of the gases, especially of CO2, causes good pre-mixing of the glass melt. The gas generation and thus the pre-mixing are concluded at temperatures of about 800° C. to 1100° C.
- The largest amount of gas escapes of course during the initial melting of the glass, but a considerable portion of the gas is captured by the melt. A portion of the captured gases is dissolved in the glass melt, but another portion remains as local gas inclusions, as so-called bubbles, in the glass melt. The bubbles shrink or grow when the bubble internal pressure is lower or higher than the equilibrium pressure of the dissolved gas. The gas bubbles have different sizes.
- The resulting melt is thus designated a raw melt. However it has very distinct streaking or regions of varying index of refraction and many bubbles, which impair the quality of a glass and/or glass-ceramic body that is made from the glass melt. Because of this reason the still strongly streaked and bubble containing glass melt is heated further and homogenized by means of mechanical stirring elements, by chopping with fine needles or by blowing oxygen into it through fine nozzles. These methods refine the glass melt of the gas bubbles.
- The term “refinement” or “refining” of the glass means a melting process comprising sequential melting process steps performed in so-called refining chambers, which
- removes gas bubbles of a predetermined size class; and
- guarantees a certain adjustment of the gas content of the glass melt and at the same time
- is to be integrated in a complex sequence of melt processing steps.
- The refinement of the glass is thus of the greatest significance for the quality of the end product of the melting process.
- Different methods have been formulated for the refinement.
- The gas bubbles have the tendency to rise in the melt due to their buoyancy and to escape into the atmosphere from the vessel containing the melt. Since this process however takes a considerable time without other influences, it would make a production process using it expensive because of its long dwell time for the refinement. It is thus known however to produce higher temperatures in the refining zone so that the viscosity of the melt and thus the bubble rising speed is increased and so that the bubble diameter also increases. These additional temperature increases however require considerable energy, which similarly greatly increases the process costs.
- The chemical refinement of glass has been well tested and further optimized. Chemical refining agents and of course oxides are added to the melt in temperature-dependent oxidation stages. Common refining agents include Sb(V) oxide, As(V) oxide and Sn(IV)-oxide. An increased mixing of the melt and thus an improved homogenization is obtained by oxygen released in situ by the refining agents or by additional mechanical gas introduction. Moreover the additional release of oxygen causes growth of small gas bubbles present already in the glass melt.
- Small bubbles are pumped up with the refining gas O2 arising from the refining agent during chemical refinement. The resulting larger bubbles formed more rapidly rise in the glass melt. The refinement thus leads to removal of the glass inclusions, which leads to a higher quality product.
- The chemical refinement also comprises a sequence of elementary steps interlaced with each other spatially and temporally. First the finely dispersed bubbles in the raw melt are greatly inflated by the refining oxygen gas so that a drastic shortening of the bubble rise time occurs. At the same time the refining bubbles extract gas dissolved in the glass. As much as possible, resorption of the unavoidably present residual bubbles occurs in the subsequent cooling steps. Color, moisture content and the so-called reboil conditions for O2 and SO2 are the targeted parameters for a successful adjustment of the gas content of the glass. Once a satisfactory bubble quality is obtained it is not impaired in subsequent cool-down or casting processes.
- Chemical refinement has several principal disadvantages. First the methods. First these methods do not function well for every glass system, especially during NaCl refinement, or only at higher temperature, which also requires much time, since gas diffusion in the melt takes too long. Thus the refining chambers must be comparatively large, which further increases product costs. Finally the chemical refining agents change the chemistry of the glass and thus its properties. Moreover arsenic oxide is extremely poisonous and the required purity is not reached without more work. Major environmental problems are also connected both with its manufacture and its use. They also occur for antimony oxide. Cerium oxide itself is of course not poisonous, but it is extremely expensive so that its use is limited to specialty glass.
- So-called physical refining methods, which do not impair or damage the chemistry of the glass, are also known because of these disadvantages for chemical methods. The physical refinement of a glass melt is based on the “forcing” of the bubbles to the surface of the melt, where they are destroyed and their gas content released or on their dissolution in the melt.
- DE-A 3 022 091 described an apparatus for melting glass in a melt oven with a refining device for refinement of the glass and at least one receiver in which a direct current is applied to a heated electrode formerly or usually operated with alternating current.
- A method and apparatus for melting of those glasses which have a high reducing action in a melted state are described in DE-A 3 906 270. Especially in phosphate glass, whose reducing action is even more pronounced in the melted state, erosion by immersion of platinum parts should be avoided. The reducing action of phosphate glass is so great that the glass reacts with platinum or a platinum alloy of the melt-containing vessel to form a platinum-phosphorous alloy. This platinum-phosphorous alloy however has a melting point of 588° C., which is below the glass melt temperature. This alloy is dissolved in the melt, which leads to the dissolving of the platinum glass melt-containing vessel. This is also the situation for platinum stirring tools or elements. According to this publication this is avoided by supplying the environment of the glass melt container, i.e. its outer surface, with oxygen. The interior surface, which is in contact with the glass melt, is protected by an oxygen rich glass layer formed by the oxygen. Thus the use of platinum containers is possible, which avoids the use of ceramic melt-containing vessels, which impair the optical quality of the glass. In this process however conditions must be selected in which the oxygen permeability of the platinum container is guarantied, which is achieved by raising the temperature.
- U.S. Pat. No. 5,785,726 describes a method of making glasses for flat display screens, especially LCDs (Liquid Crystal Displays) and TFTs (Thin Film Transistors). In this method the production of oxygen bubbles arising in the cool-down region, the so-called “O2-reboil”, is avoided by rinsing the platinum parts of the cool-down region at least partially with hydrogen. The oxygen present in the glass melt is reduced to water by the hydrogen-permeable platinum vessel in this way, whereby oxygen gas bubbles are dissolved.
- It is an object of the present invention to provide an improved method for refining and homogenizing a glass melt in which the use of arsenic oxide, antimony oxide and cerium oxide can be avoided.
- It is also an object of the present invention to provide an apparatus for performing the improved method.
- These objects are attained by the method and apparatus described in the appended claims.
- Surprisingly it has been found that, although noble metals are not oxygen permeable, conducting oxygen through a device having a noble metal sleeve or casing, such as a noble metal pipe, which is immersed or dipped in a liquid containing water and/or hydroxyl groups, for example a glass melt, vigorously generates oxygen bubbles in the liquid. This gas generation is so great, that the liquid, which is the glass melt, is very thoroughly mixed by the vigorous bubble generation. Because of this gas generation the schlieren present is dissipated and the small bubbles present are inflated, so that they rise faster. The conduction of oxygen through a platinum pipe immersed or dipped in a glass melt thus leads to very great oxygen bubble development in the melt and thus to a removal of gas inclusions in the melt.
- It is possible in this way to avoid the use of very expensive and/or poisonous chemical refining agents. Glass of higher purity may thus be prepared according to the methods of the invention, which is free of gas inclusion and free of additional impurities introduced by the refinement.
- The method according to the invention is also suitable for removal of water residues and/or hydroxyl residues.
- Furthermore this method is very well controlled by adjusting the oxygen content and/or partial pressure of oxygen in the gas flow. The method is appropriately not limited to a definite temperature as is required in many chemical and other physical refining processes.
- The noble metals which are suitable for use in this method are principally all those noble metals, which are particularly hydrogen permeable at the conditions occurring in the glass melt, i.e. those which have a high hydrogen diffusion coefficient. Platinum and all metals belonging to the platinum group metals, gold, rhenium or alloys thereof, are suitable. According to the invention other materials may be used for the noble metal member, which are stable at the process temperatures and which have a bridge or portion of the foregoing of noble metals. The bridge or portion of the noble metals must extend between the outside surface or outer side facing the glass melt and the inner or interior side of the noble metal member. This type of bridge can be a network or a number of fibers. A platinum vessel and/or platinum dish can be used as the noble metal member. It is most important that the oxygen acts only on those regions of the melt-containing vessel in which the refining occurs. In a preferred embodiment of the method of the invention, a noble metal pipe is arranged, especially in the region in which the refining step occurs. Preferably the pipe runs to the vessel bottom. This sort of pipe appropriately has a meandering shape, which preferably passes through the entire refining region. It some cases it has proven to be sufficient when the oxygen-rinsed noble metal pipe is installed at a single place in the refining region. In its simplest form the oxygen-rinsed noble metal pipe is a U-shaped pipe, which is arranged in the melt so that it is either dipped in the melt from above or is guided through the melt from below. In both cases the horizontal portion of the U-shaped pipe extends along the vessel bottom or is spaced a short distance from it.
- In an additional preferred embodiment the noble metal member includes a stirrer rinsable with oxygen gas. In this way the advantageous features may be combined with each other, which produce mechanical stirring of the melt and thorough mixing. This leads to a particularly efficient homogenizing and refining.
- Air and oxygen-containing waste air from process gas, such as exhaust gas from combustion, especially from gas and oil burners. However it is also possible to use pure oxygen in the method according to the invention.
- In another preferred embodiment of the process the oxygen input is controlled by means of a control element. This preferably happens so that the oxygen partial pressure of the melt is determined by means of a probe, such as the probe described by Frey, Schaeffer and Baucke in Glasstechn. Ber. [Glass Engineering Report] 53, pp. 116-123 (1980). The oxygen input to the noble metal member can be exactly controlled by means of a control device responding to the measured values from the probe. Since other gases, such as CO2 or also SO2, are also removed by the oxygen refining, the oxygen input can also be controlled by a suitable SO2- or CO2-probe.
- In an additional embodiment according to the invention the oxygen introduced into the glass melt by the refining process according to the invention is removed in a process step occurring after the refining. This can occurs for example by working at low pressure besides the known physical methods. The dissolved oxygen and/or the minute, frequently invisible gas bubbles still present expand under a low pressure, so that they rapidly rise to the surface of the melt. In another possible embodiment the melt is acted on by pressure in this process step so that a so-called “forcing off” of the bubble formation occurs.
- It is especially preferred however in a particularly advantageous embodiment of the method to arrange an additional hydrogen permeable noble metal member in the melt and to act on it with hydrogen, hydrogen-containing gas or gases and/or vapors, which split off hydrogen at higher temperatures, such as water and/or ammonia. In this way oxygen still present in the melt is reduced to water and/or to hydroxyl groups, which are dissolved in the glass melt and in the finished glass. These latter products have no noteworthy influence on the glass quality of the finished glass. Preferably a control device or member controls the hydrogen feed in this step. The control device or member itself receives its control signals from an oxygen probe dipped in this region of the glass melt.
- The oxygen is preferably removed in the cool-down region. This means that the appropriate additional noble metal member is arranged in this region. The additional noble metal member can be formed, as a whole, like the noble metal member described above for generating oxygen in the melt. The so-called feeder trough is an additional preferred location for removal of oxygen from the glass melt.
- The invention also includes an apparatus for performing the foregoing method. The apparatus according to the invention includes a region, in which the liquid, especially the glass melt, is in contact with a noble metal member. The noble metal member has one side facing the liquid and/or glass melt and another side acted on with the oxygen that is facing away from the liquid and/or glass melt. In a special embodiment of the apparatus this noble metal member is the vessel base or bottom, in which the glass melt is refined. In another preferred embodiment of the apparatus of the invention the noble metal member is a mechanical stirrer, whose interior side can be rinsed with the oxygen gas.
- The glasses obtained by the method according to the invention are especially suitable for making electronic tubes, such as display screens, especially televisions and computer monitors, as well as flat screen devices, such as LCDs and TFTs. Also the glasses obtained by the method according to the invention are especially suitable for optical lenses and units and devices containing them. Lamp glass and glass for light sources are also suitable applications. The glasses obtained by the method according to the invention are also suitable for making cooking panels for hearth, such as Ceran® panel, and for cooking-ware (Jenaerglass®) and for microwave cooking units.
- The objects, features and advantages of the invention will now be illustrated in more detail with the aid of the following description of the preferred embodiments, with reference to the accompanying figures in which the sole FIGURE is a flow chart for the method of refining a glass melt according to the invention.
- The sole FIGURE shows a
glass melt vessel 10, in which the minerals used to make glass, such as quartz, soda, lime, marble, etc, are supplied in a finely divided or ground heap. Following that these solids are melted in amelting region 20 and then flow further into therefining region 30 of thevessel 10. Anoble metal pipe 40, which includes anoxygen inlet section 42 and anoxygen outlet section 44, is arranged in therefining region 30 at the bottom of thevessel 10. Theoxygen inlet section 42 is controlled by means of afirst control device 50, which receives control signals from afirst oxygen probe 60 immersed or dipped in therefining region 30. Themelt region 20 and therefining region 30 of theglass melt vessel 10 are separated from a cool-down region 70 by means of a separatingwall 80, which does not reach to the surface of the glass melt. In the cool-down region 70 anothernoble metal pipe 90, which is formed in a similar manner to the oxygen supplyingnoble metal pipe 40, is arranged. This othernoble metal pipe 90 is washed or rinsed with hydrogen, water vapor or mixtures of them with other gases. The hydrogen supply in thepipe 90 is controlled by means of asecond control device 100, which receives its control signals from asecond oxygen probe 110, which is arranged in the cool-down region 70 or after it. - The disclosure in
German Patent Application 100 09 425.2 of Feb. 28, 2000 is incorporated here by reference. This German Patent Application describes the invention described hereinabove and claimed in the claims appended hereinbelow and provides the basis for a claim of priority for the instant invention under 35 U.S.C. 119. - While the invention has been illustrated and described as embodied in a method and apparatus for oxygen refining of a glass melt and glasses manufactured by a process using this method and/or apparatus, it is not intended to be limited to the details shown, since various modifications and changes may be made without departing in any way from the spirit of the present invention.
- Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
Claims (6)
1-10. (canceled)
11. An apparatus for refining a glass melt, said apparatus comprising a glass melt-containing vessel (10) including a refining region (30) in which said glass melt is refined and a noble metal member (40) arranged in the refining region (30) and wherein said noble metal member has one side facing said glass melt and another side acted on with oxygen facing away from the glass melt.
12. The apparatus as defined in claim 11 , wherein at least a portion of said one side of said noble metal member facing said glass melt contacts said glass melt and said another side facing away from the glass melt does not contact said glass melt.
13. The apparatus as defined in claim 11 , wherein said vessel (10) has a vessel bottom part and said noble metal member consists of said vessel bottom part.
14. The apparatus as defined in claim 11 , wherein said noble metal member is a mechanical stirring device.
15. A glass for at least one of liquid crystal display devices, thin film transistors, monitors, television picture tubes, optical lenses, cooking units, microwave units, electrical devices, cooking ranges, window glass, lamp glass and display glass, wherein said glass is made by a method including refining a glass melt, said refining comprising the steps of:
a) arranging at least one noble metal member in the glass melt, said at least one noble metal member having an inner surface facing away from the glass melt and an outer surface facing toward the glass melt; and
b) bringing oxygen or an oxygen-containing gas mixture into contact with the inner surface of the at least one noble metal member facing away from the glass melt so as to act on the inner surface with said oxygen or said oxygen-containing gas.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/845,944 US20040206126A1 (en) | 2000-02-28 | 2004-05-14 | Method and apparatus for oxygen refinement of a glass melt |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10009425A DE10009425A1 (en) | 2000-02-28 | 2000-02-28 | Production of glass, e.g., for liquid crystal displays, thin film transistors and monitors comprises arranging a precious metal element in a cuvette containing a glass melt, and refining with oxygen |
DE10009425.2 | 2000-02-28 | ||
US09/793,041 US6769272B2 (en) | 2000-02-28 | 2001-02-26 | Method and apparatus for oxygen refinement of a glass melt |
US10/845,944 US20040206126A1 (en) | 2000-02-28 | 2004-05-14 | Method and apparatus for oxygen refinement of a glass melt |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/793,041 Division US6769272B2 (en) | 2000-02-28 | 2001-02-26 | Method and apparatus for oxygen refinement of a glass melt |
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US20040206126A1 true US20040206126A1 (en) | 2004-10-21 |
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Family Applications (2)
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US09/793,041 Expired - Fee Related US6769272B2 (en) | 2000-02-28 | 2001-02-26 | Method and apparatus for oxygen refinement of a glass melt |
US10/845,944 Abandoned US20040206126A1 (en) | 2000-02-28 | 2004-05-14 | Method and apparatus for oxygen refinement of a glass melt |
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US09/793,041 Expired - Fee Related US6769272B2 (en) | 2000-02-28 | 2001-02-26 | Method and apparatus for oxygen refinement of a glass melt |
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US (2) | US6769272B2 (en) |
EP (1) | EP1127851B1 (en) |
JP (1) | JP2001294428A (en) |
CA (1) | CA2337579A1 (en) |
DE (2) | DE10009425A1 (en) |
ES (1) | ES2246946T3 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060242995A1 (en) * | 2005-04-27 | 2006-11-02 | Bookbinder Andrea W | Method of fining glass |
US20120125050A1 (en) * | 2010-09-30 | 2012-05-24 | Avanstrate Inc. | Method for manufacturing glass plate |
US11505487B2 (en) * | 2017-03-16 | 2022-11-22 | Corning Incorporated | Method for decreasing bubble lifetime on a glass melt surface |
Families Citing this family (17)
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TWI276611B (en) * | 2000-08-17 | 2007-03-21 | Hoya Corp | Process for producing glass and glass-melting apparatus thereof |
EP1184345B1 (en) * | 2000-09-04 | 2007-03-21 | Schott Ag | Method for suppressing the formation of oxygen bubbles in a glass melt, apparatus used therefor and application of the glass so obtained |
EP1337686B1 (en) * | 2000-11-30 | 2007-03-14 | Schott Ag | Coated noble metal element used for producing glass |
US6993936B2 (en) * | 2003-09-04 | 2006-02-07 | Corning Incorporated | System and method for suppressing the formation of oxygen inclusions and surface blisters in glass sheets and the resulting glass sheets |
DE102004007436B4 (en) | 2004-02-16 | 2017-11-16 | Schott Ag | Use of a B2O3-free crystallization-stable aluminosilicate glass and its preparation |
DE102004015577B4 (en) * | 2004-03-30 | 2012-08-23 | Schott Ag | Process for producing glass while avoiding bubbles on precious metal components |
DE102004022936A1 (en) | 2004-05-10 | 2005-12-08 | Linde Ag | Process for refining glass |
DE102004033653B4 (en) | 2004-07-12 | 2013-09-19 | Schott Ag | Use of a glass for EEFL fluorescent lamps |
US7854144B2 (en) * | 2005-07-28 | 2010-12-21 | Corning Incorporated | Method of reducing gaseous inclusions in a glass making process |
US7584632B2 (en) * | 2005-07-28 | 2009-09-08 | Corning Incorporated | Method of increasing the effectiveness of a fining agent in a glass melt |
US7454925B2 (en) * | 2005-12-29 | 2008-11-25 | Corning Incorporated | Method of forming a glass melt |
US20090272150A1 (en) * | 2007-11-02 | 2009-11-05 | Lawrence Henry Kotacska | Corrosion-resistant cradle and castable materials for glass production |
US8925353B2 (en) * | 2007-11-08 | 2015-01-06 | Corning Incorporated | Process and system for fining glass |
US20100199721A1 (en) * | 2008-11-12 | 2010-08-12 | Keisha Chantelle Ann Antoine | Apparatus and method for reducing gaseous inclusions in a glass |
KR102377995B1 (en) | 2014-09-29 | 2022-03-23 | 코닝 인코포레이티드 | Glass inlet tube environmental control |
US10941700B2 (en) | 2019-03-11 | 2021-03-09 | Garrett Transportation I Inc. | Turbocharger turbine wastegate assembly |
US11697608B2 (en) * | 2019-10-01 | 2023-07-11 | Owens-Brockway Glass Container Inc. | Selective chemical fining of small bubbles in glass |
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US2331052A (en) * | 1941-11-27 | 1943-10-05 | Owens Illinois Glass Co | Method of refining molten glass |
US3233993A (en) * | 1962-03-06 | 1966-02-08 | Bausch & Lomb | Apparatus for processing a vitreous composition |
US4227909A (en) * | 1979-06-12 | 1980-10-14 | Owens-Illinois, Inc. | Electric forehearth and method of melting therein |
JPH01219028A (en) | 1988-02-29 | 1989-09-01 | Hoya Corp | Method for melting glass |
JPH0248422A (en) * | 1988-08-09 | 1990-02-19 | Tanaka Kikinzoku Kogyo Kk | Stirring rod for glass industry |
US5643350A (en) * | 1994-11-08 | 1997-07-01 | Vectra Technologies, Inc. | Waste vitrification melter |
KR100444628B1 (en) * | 1995-11-21 | 2004-11-03 | 아사히 가라스 가부시키가이샤 | Method and apparatus for refining molten glass |
US5785726A (en) * | 1996-10-28 | 1998-07-28 | Corning Incorporated | Method of reducing bubbles at the vessel/glass interface in a glass manufacturing system |
EP1184345B1 (en) * | 2000-09-04 | 2007-03-21 | Schott Ag | Method for suppressing the formation of oxygen bubbles in a glass melt, apparatus used therefor and application of the glass so obtained |
-
2000
- 2000-02-28 DE DE10009425A patent/DE10009425A1/en not_active Ceased
-
2001
- 2001-02-20 CA CA002337579A patent/CA2337579A1/en not_active Abandoned
- 2001-02-23 ES ES01104378T patent/ES2246946T3/en not_active Expired - Lifetime
- 2001-02-23 DE DE50107394T patent/DE50107394D1/en not_active Expired - Fee Related
- 2001-02-23 EP EP01104378A patent/EP1127851B1/en not_active Expired - Lifetime
- 2001-02-26 US US09/793,041 patent/US6769272B2/en not_active Expired - Fee Related
- 2001-02-27 JP JP2001051480A patent/JP2001294428A/en not_active Withdrawn
-
2004
- 2004-05-14 US US10/845,944 patent/US20040206126A1/en not_active Abandoned
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060242995A1 (en) * | 2005-04-27 | 2006-11-02 | Bookbinder Andrea W | Method of fining glass |
US7475568B2 (en) | 2005-04-27 | 2009-01-13 | Corning Incorporated | Method of fining glass |
US20120125050A1 (en) * | 2010-09-30 | 2012-05-24 | Avanstrate Inc. | Method for manufacturing glass plate |
US11505487B2 (en) * | 2017-03-16 | 2022-11-22 | Corning Incorporated | Method for decreasing bubble lifetime on a glass melt surface |
Also Published As
Publication number | Publication date |
---|---|
US6769272B2 (en) | 2004-08-03 |
DE50107394D1 (en) | 2005-10-20 |
EP1127851A2 (en) | 2001-08-29 |
ES2246946T3 (en) | 2006-03-01 |
EP1127851A3 (en) | 2003-02-05 |
CA2337579A1 (en) | 2001-08-28 |
EP1127851B1 (en) | 2005-09-14 |
US20030196453A1 (en) | 2003-10-23 |
JP2001294428A (en) | 2001-10-23 |
DE10009425A1 (en) | 2001-09-06 |
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AS | Assignment |
Owner name: SCHOTT AG, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SCHOTT GLAS;REEL/FRAME:015766/0926 Effective date: 20050209 Owner name: SCHOTT AG,GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SCHOTT GLAS;REEL/FRAME:015766/0926 Effective date: 20050209 |
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STCB | Information on status: application discontinuation |
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