JP4721290B2 - Glass manufacturing method and glass melting apparatus used therefor - Google Patents

Description

  The present invention relates to a glass manufacturing method and a glass melting apparatus used therefor. More specifically, the present invention relates to a glass production method for obtaining high-quality glass using a raw material particularly rich in reactivity and a glass melting apparatus used therefor.

  An optical glass having a low refractive index [nd], a large Abbe number [νd], and exhibiting positive anomalous dispersion is one of important glasses in optical design used for correcting a secondary spectrum. Examples of such optical glass include fluorophosphate glasses described in Patent Document 1 and Patent Document 2.

The fluorophosphate glass is composed of a metaphosphate compound M (PO ₃ ) x and a fluorine compound MF x (where M is an alkali metal element, alkaline earth metal element, or other metal element, and x is a valence of M). Can be produced by melting these raw materials.

  This fluorophosphate glass is a useful glass, but exhibits extremely strong erosion when the glass raw material is melted. Therefore, even if it is melted using a platinum container with excellent corrosion resistance, the platinum is corroded, and the corroded platinum becomes fine particles that are mixed into the molten glass and become a light scattering source. There was a problem of lowering.

  In view of this, a method for producing glass containing a high amount of fluorine has been proposed for the purpose of reducing the contamination of the glass due to the brittle damage of the melting vessel and homogenizing defoaming (see Patent Document 3). However, in this manufacturing method, even if the defoaming promoting effect is obtained, it is not possible to completely prevent the glass contamination caused by the container erosion. Furthermore, this method has a problem that the raw material composition is unavoidably limited.

In addition, a method for reducing platinum contamination by melting metaphosphate M (PO ₃ ) x , which is a raw material of phosphate glass, after heat treatment has been reported (see Non-Patent Document 1). This method is a method in which a glass raw material is heated at 920 to 1050 ° C. and then melted. However, in this method, there may be no problem in the case of only a metaphosphoric acid raw material having a high vitrification temperature of 1100 to 1200 ° C., but it cannot be used in a raw material mixed with a fluorine compound raw material that vitrifies at 700 to 1000 ° C. . Therefore, it cannot be applied to a glass composition material having a vitrification temperature of 1000 ° C. or lower, such as fluorophosphate glass. Dare when you try to apply a step of heating the M (PO ₃₎ x material, and M (PO ₃₎ x raw material heat treatment requires a step of mixing the fluorine compound MFx material is another material The manufacturing process becomes complicated, and there is a problem that the manufacturing cost is unavoidable.

  Furthermore, in the melting of fluorophosphate glass, the reaction product of glass vapor at the time of melting and moisture in the atmosphere solidifies in the melting container, reacts with the glass raw material to block the raw material inlet, It falls into the molten glass and causes an unfavorable situation such as violent foaming or remaining in the glass as an undissolved substance. As a result, problems such as a reduction in glass quality and productivity are caused.

  For the above reasons, it is difficult to manufacture high-quality fluorophosphate glass at the mass production level.

On the other hand, even when melting borosilicate glass, a large amount of moisture is released when the glass raw material is melted, and the raw material inlet is clogged, or boric acid is volatilized and solidifies in a melting container, which is the same as melting fluorophosphate glass. The problem is happening.
JP 60-81042 A JP-A-62-100452 Japanese Patent Publication No. 8-25749 "Platinum Metals Review" Volume 36, No. 1, pages 14-25 (1992)

  Under such circumstances, the present invention uses a glass raw material that contains a component that is highly reactive in the melting process or contains a component that easily volatilizes, such as the production of fluorophosphate glass or borosilicate glass. It aims at providing the manufacturing method of glass for manufacturing glass, and the glass melting apparatus used for it.

The present inventors have made intensive studies in order to achieve the object, fulfills the container in a dry ambient gas, while flowing the atmosphere gas along a shooting path of the glass raw material to molten glass liquid surface The inventors have found that the object can be achieved by a method of introducing glass raw materials and a glass melting apparatus having a specific structure capable of carrying out these methods, and the present invention has been completed based on this finding.

That is, the present invention is,
(1 ) A glass production method comprising a step of charging a molten glass in a heated container with the raw material of the glass and melting the glass, filling the container with a dry atmosphere gas, A glass production method (hereinafter referred to as production method II), wherein the glass raw material is introduced while flowing to the molten glass liquid surface along the glass material introduction route, and
(2 ) A glass melting apparatus for charging a glass raw material to obtain molten glass by heating and melting. The glass raw material is heated and melted, and a container for storing the obtained molten glass is connected to the container. A raw material charging port provided, an atmospheric gas supply port for supplying a dry atmospheric gas filling the container, and an atmospheric gas exhaust port for exhausting the atmospheric gas are provided as main components, and glass from the atmospheric gas supply port A glass melting apparatus (hereinafter referred to as the glass melting apparatus) characterized in that the inside of the container is divided so as to form a flow path of the atmospheric gas that leads to the molten glass liquid surface along the raw material charging path and reaches the exhaust port. Called Glass Melting Equipment II),
Is to provide.

  By using the glass manufacturing method and glass melting apparatus of the present invention, it is possible to produce high-quality glass, particularly phosphate glass, fluoride glass, fluorophosphate glass, boric acid-containing glass, etc., using highly reactive raw materials. Can be manufactured well.

  The glass production method of the present invention is a glass production method comprising a step of charging a molten glass in a heated container with a raw material of the glass and melting the glass, and has two modes: (1) A method of bubbling an oxidizing gas in the molten glass, and a method of introducing a raw material showing reducibility into the bubbling position during the melting process (production method I); and (2) filling the inside of the container with a dry atmosphere gas There is a method (manufacturing method II) in which the glass raw material is introduced while flowing the atmospheric gas along the glass raw material introduction path to the molten glass liquid surface.

  In the production method I, the glass raw material exhibiting reducibility in the process of being melted is a raw material that generates a substance that corrodes the container (particularly platinum or platinum alloy container) in the course of melting, The raw material of phosphate glass corresponds to such a raw material. The oxidizing gas is a gas that can oxidize a reducing substance produced from the glass raw material, and oxygen gas or the like corresponds to this.

  The production method I is preferably applied when using a metaphosphate compound as a glass raw material and melting a phosphate glass, particularly when using a metaphosphate compound and a fluorine compound as a glass raw material and melting a fluorophosphate glass.

  On the other hand, the production method II uses a fluorine compound as a glass raw material, melts fluoride glass, particularly uses a fluorine compound and a metaphosphate compound, melts a fluorophosphate glass, or uses a borate compound, boric acid. It is preferably applied when melting the containing glass.

Fluorophosphate glass is an optical glass that has a large νd value by fluorine element and exhibits a large positive anomalous dispersion, and uses fluorine compound MFx and metaphosphate compound M ′ (PO ₃ ) x ′ as raw materials. Made by melting. Here, M and M ′ each represent a metal element, for example, one or more kinds of metal elements composed of alkali metal elements, alkaline earth metal elements, or other metal elements, and x, x ′ Represents the valences of M and M ′, respectively.

Examples of the raw material for fluorophosphate glass include aluminum fluoride AlF ₃ , magnesium fluoride MgF ₂ , calcium fluoride CaF ₂ , strontium fluoride SrF ₂ , yttrium fluoride YF ₃ (above, fluorine compound), aluminum metaphosphate Al (PO ₃ ) ₃ and barium metaphosphate Ba (PO ₃ ) ₂ (above, metaphosphate compound) can be exemplified. In addition, KPO ₃ , NaPO ₃ , H ₃ PO ₄ , P ₂ O ₅ , Nd ₂ (PO ₃ ) _{3 and the} like may be used. The phosphoric acid compound is a raw material for phosphate glass.

This glass raw material is put into molten glass in a container heated to about 800 to 1000 ° C., but among the glass raw material, metaphosphate compound M (PO ₃ ) x is decomposed at the time of melting and has a strong reducing action. Generates the free phosphorus shown. This free phosphorus corrodes the platinum container, and the corroded platinum fine particles are mixed into the molten glass, become a light scattering source, and cause the quality of the glass to deteriorate.

  In order to solve such a problem, the manufacturing method I and the manufacturing method II can be applied in the present invention. First, the manufacturing method I will be described.

In the production method I of the present invention, an oxidizing gas is supplied to the molten glass and bubbled. Then, the metaphosphate compound is introduced into the position where the oxidizing gas is bubbled. The charged metaphosphate compound is decomposed to generate free phosphorus having a strong reducing action, but the free phosphorus is quickly oxidized by the bubbles of the oxidizing gas before coming into contact with the inner surface of the container, thereby preventing the corrosion of the container.

  Thus, by oxidizing the free phosphorus which is the decomposition product of the metaphosphate compound, the melting of the glass is promoted, and the phosphate glass can be obtained efficiently.

  The oxidizing gas not only oxidizes free phosphorus but also causes upward convection at the position where the metaphosphate compound is introduced. Usually, the charged raw material settles and reaches the bottom of the container, but the sedimentation speed of the raw material is slowed by convection by bubbling. Therefore, the raw material is decomposed before reaching the bottom of the container, and the generated free phosphorus is oxidized, so that the corrosion of the bottom of the container can be effectively prevented.

  In this production method I, it is preferable that an oxidizing gas is bubbled at the center of the molten glass liquid surface and a metaphosphate compound is introduced into the bubbling position. By doing in this way, while making it possible for the free phosphorus produced by decomposition | disassembly of a raw material to reach a container wall surface, the molten glass in a container is stirred.

  The oxidizing gas used for bubbling is preferably a dry gas containing oxygen gas such as oxygen gas or a mixed gas of oxygen gas and inert gas. Further, it is desirable to use an oxidizing gas in a dry state for the reason described later, and a gas having a water content of 4.25 ppm by volume or less or a dew point of -70 ° C. or less is used. It is preferable. The amount of oxygen gas is preferably 50 to 500 cc / min.

  The bond dissociation energy of fluorine and metal in the fluorine compound as a glass raw material is about 511.7 kJ / mol for F-Mg, 587.7 kJ / mol for F-Al, 556.17 kJ / mol for F-Ca, and about 500 kJ / mol. That's it. On the other hand, since the bond dissociation energy of O-Mg is smaller than the bond dissociation energy with F, such as 336.87 kJ / mol and O-Al with 478.7 kJ / mol, the bubbled oxygen gas is composed of fluorine and metal. The bond is not broken and fluorine is not expelled from the glass. Therefore, oxygen gas oxidizes free phosphorus, but it is difficult to reduce fluorine content in glass by oxidizing fluorine, so it is suitable as a bubbling gas when producing fluorophosphate glass. In particular, when fluorophosphate glass is used as optical glass, low refractive index and low dispersion characteristics are required. However, if fluorine substitutes for oxygen, the νd value (Abbe number) decreases. However, this decrease in νd value can be prevented by selecting dry oxygen gas as the oxidizing gas.

  The flow rate of the oxidizing gas depends on the input amount of raw materials and the production amount of molten glass, but is preferably 1 to 4 liters / minute, and the temperature outside the container before being fed into the melting container is 20 It is preferable to set the temperature when supplying to molten glass to 700 to 800 ° C. to 700 to 800 ° C.

  By making the depth of the molten glass at the raw material charging position (the difference in height between the bottom of the container and the molten glass liquid level at this position) deeper and lowering the height of the raw material charged based on the molten glass liquid level, Can reach the bottom of the container for a long time, so that even if a large amount of erodible raw material is added, the wall of the container can be prevented from eroding. In order to obtain the above-mentioned effect without the raw material inlet close to the molten glass liquid level, the depth of the molten glass at the position where the glass raw material is charged is set to 1 of the raw material input height based on the liquid surface of the molten glass. It is preferably 5 to 3 times, more preferably 1.6 to 2.5 times. The height of the molten glass liquid surface can be controlled by controlling the supply amount of the glass raw material to the molten glass, the discharge amount of the molten glass from the container, or both the supply amount and the discharge amount.

  In addition, it is preferable to supply glass raw material continuously. In the case of producing a certain amount of glass, the method of intermittently adding glass raw materials increases the raw material input amount at a time and generates a large amount of free phosphorus at a time. In the continuous charging, the charging amount can be averaged with respect to time, and the generated free phosphorus can be oxidized steadily, which is advantageous from the viewpoint of preventing corrosion of the container and promoting melting of the glass.

  Therefore, in order to keep the liquid level of the molten glass within the predetermined range, it is preferable to continuously supply the glass raw material and continuously discharge the molten glass.

  The molten glass is sent to the clarification tank from the outlet of the container, clarified and stirred, and becomes a high-quality glass that is uniform and does not contain fine particles and bubbles that become a light scattering source. Since this glass is high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass.

The above method exemplifies melting of fluorophosphate glass, but can also be applied to melting of phosphate glass.
Next, Production Method II will be described.

Many fluorine compounds, which are raw materials for fluorophosphate glass, tend to sublime, such as AlF ₃ (sublimation at 1260 to 1272 ° C.). AlF ₃ is partially decomposed when exposed to water vapor at 300 to 400 ° C. to produce hydrogen fluoride and aluminum oxide. The vapor pressure of AlF ₃ is 2.19 kPa (1098 ° C.) and 0.102 MPa (1294 ° C.). Further, P ₂ O ₅ has a property of being easily vaporized. For this reason, if there is OH group or water vapor in the atmosphere in contact with the molten glass, the AlF ₃ vapor and P ₂ O ₅ vapor react with the OH group or H ₂ O vapor to produce hardly soluble AlPO ₄ , It condenses above the molten glass liquid surface. The solidified AlPO ₄ drops and mixes in the glass irregularly. However, when AlPO ₄ falls into the molten glass, it reacts while foaming vigorously, leaving bubbles in the glass. Moreover, the melting point of AlPO ₄ is as high as 1500 ° C. or higher, and it is difficult to melt even if it falls into molten glass. Therefore, the dropped AlPO ₄ remains as a minute object, causes fine particle scattering, and remarkably deteriorates the quality of the glass. If the melting temperature of the glass is higher than about 1100 to 1150 ° C. in order to melt the minute objects, a material that tends to sublimate may be removed from the glass, so that it is difficult to obtain a glass having a desired composition. Become.

  Moreover, in order to obtain a large νd value like fluorophosphate glass, a glass containing a large amount of fluorine instead of oxygen is easy to react with water, and in the melting process, moisture directly touches the molten glass or is exposed to a molten atmosphere. Water vapor should be avoided. When the molten fluorophosphate glass comes into contact with OH groups or water vapor, fluorine ions are replaced with oxygen ions, and fluorine escapes from the glass as HF gas. For this reason, the stability as glass is impaired, or the νd value decreases when used as optical glass. The generated HF gas is harmful and adversely affects the environment.

  In order to solve such problems and obtain a high-quality fluorophosphate glass, it is necessary to reduce moisture and OH groups in the molten glass and the molten atmosphere. Therefore, in the production method II, in the process of charging and melting the raw material of fluorophosphate glass into the molten fluorophosphate glass accumulated in the heated container, the container is filled with dry atmosphere gas. Then, the glass material is charged while flowing the atmospheric gas along the glass material charging path to the molten glass liquid surface.

By this method, the inside of the container is filled with a dry atmosphere gas, and moisture in the atmosphere can be reduced. In addition, since the atmospheric gas is introduced into the molten glass liquid surface along the glass raw material introduction path, even if the glass raw material slightly adsorbs moisture, it is adsorbed by mixing with the atmospheric gas. It is possible to reduce the water content. After the atmospheric gas reaches the surface of the molten glass, the atmospheric gas is exhausted to the outside of the container, and the atmosphere in the container is kept in a dry state, so that the reaction between the molten glass and OH groups or moisture can be suppressed.

  In addition, since the atmospheric gas flows along the glass raw material charging path, the gas generated from the molten glass reaches the glass raw material supply port, solidifies the glass raw material and closes the glass raw material supply port, It is possible to prevent the raw material supply port from being blocked by rising air.

  As the dry atmosphere gas, a dry inert gas, a dry oxygen gas, or a dry mixed gas of an inert gas and an oxygen gas is preferable.

Further, in order to prevent the vaporized glass vapor comprising the glass components of AlPO ₄ , AlF ₃ and other fluorine compounds described above from solidifying and blocking the exhaust port for exhausting the atmospheric gas from the container, the temperature of the exhaust port is prevented. Is preferably heated to 600 ° C. or higher, more preferably 700 ° C. or higher.

  When the glass raw material is continuously charged, by keeping the inside of the container at a positive pressure with respect to the outside of the container with the dry atmosphere gas, it is possible to prevent water vapor from entering the container together with the supply of the raw material. The pressure difference between the inside and outside of the container is preferably 10-30 Pa or more.

  The molten glass is sent to the clarification tank from the outlet of the container, clarified and stirred, and becomes a high-quality glass that is uniform and does not contain fine particles and bubbles that become a light scattering source. Since this glass is high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass.

  The above method exemplifies melting of fluorophosphate glass, but can also be applied to melting of phosphate glass.

  The above method can also be applied to melting boric acid-containing glass, for example, borosilicate glass. The boric acid-containing glass generates a large amount of moisture at the time of melting, and boric acid has volatility. Therefore, there is a problem that glass vapor is easily solidified above the glass liquid surface of the melting container. Even in the production of boric acid-containing glass, the atmospheric gas is flowed in the same way, a predetermined flow path is formed in the melting vessel, and the glass raw material supply method is as described above, thereby solving the problems caused by glass vapor solidification. In addition, the glass raw material can be supplied smoothly, and high-quality glass can be produced with high productivity.

  Further, in this production method II, as in the production method I described above, the molten glass is bubbled with an oxidizing gas, and the inside of the container is filled with a dry atmosphere gas, and this atmosphere gas is filled along the glass material charging path. While flowing to the molten glass liquid surface, the glass can be melted by introducing a glass raw material exhibiting reducibility in the melting process to the position where the oxidizing gas of the molten glass is bubbled.

At the position where the bubbling gas springs out (which is also the glass raw material charging position), an updraft is generated in the atmosphere, but the atmospheric gas flows along the raw material charging path to prevent the glass raw material from rising. Can do. The bubbling gas that has sprung out from the surface of the molten glass serves to send out the atmospheric gas to the exhaust port, and there is no risk that the oxidizing gas will be trapped in the container. This method is suitable for producing boric acid-containing glasses such as phosphate glass, fluoride glass, fluorophosphate glass, and borosilicate glass, and can also be used for producing low-viscosity silicate glass.

  The molten glass obtained by this method is sent to the clarification tank from the discharge port of the container, clarified and stirred, and becomes a high-quality glass that is uniform and does not contain fine particles and bubbles that become a light scattering source. Since this glass is high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass.

  The glass melting apparatus of the present invention is a glass melting apparatus in which glass raw material is charged, heated and melted to obtain molten glass, and is in two modes: (1) a container for melting glass raw material and melting in the container An apparatus comprising an oxidizing gas supply port for supplying an oxidizing gas to glass and a raw material charging port for supplying a glass raw material disposed above the oxidizing gas supply port as main components (glass melting apparatus I ), And (2) a container that heats and melts the glass raw material and stores the obtained molten glass, a raw material charging port that is connected to the container, and an atmosphere that supplies a dry atmosphere gas that fills the container A gas supply port and an atmospheric gas exhaust port for exhausting the atmospheric gas are provided as main components, and from the atmospheric gas supply port to the molten glass liquid surface along the glass raw material charging path, As the flow path of the atmospheric gas reaches the air inlet is formed, which the interior of the container is partitioned is (glass melter II).

First, the glass melting apparatus I will be described.
In the glass melting apparatus I, a heater for heating the molten glass stored in the container and the glass raw material charged in the container is attached to the outside of the container for melting the glass raw material. One or a plurality of oxidizing gas supply ports for supplying an oxidizing gas such as a dried oxygen gas are provided at the bottom of the container where the molten glass is stored. Above the oxidizing gas supply port, a raw material input port for supplying the glass raw material to the container is provided. The number of raw material inlets is not limited to one. During operation of this apparatus, molten glass is stored in the container, and oxidizing gas is supplied into the molten glass from the above-described oxidizing gas supply port, and bubbling is performed.

  And glass raw material is supplied from a raw material inlet, and it falls to the position bubbling with the oxidizing gas of molten glass. The introduced glass material is decomposed to generate an intermediate product that exhibits a strong reducing action, but is quickly oxidized by bubbling with an oxidizing gas, preventing corrosion of the inner wall of the container and promoting melting of the glass. .

  The glass raw material inlet is preferably provided above the center of the container so that the charged raw material is difficult to touch the container wall surface, and the oxidizing gas supply port is located at the central part of the container according to the position of the raw material inlet. It is preferable to provide it.

  The apparatus I of the present invention is suitable for melting and producing fluorophosphate glass using a fluorine compound and a metaphosphate compound as raw materials, and the oxidizing gas may be dry oxygen gas or dry gas containing oxygen gas. desirable. About the temperature and supply amount of oxidizing gas, and other conditions, it is the same as the description regarding the manufacturing method I of glass mentioned above. In addition, it is desirable that the container is made of platinum or a platinum alloy at least at the part where the molten glass touches.

  This apparatus I preferably has a charging mechanism for controlling the glass raw material charging amount into the container and a discharge amount control mechanism for controlling the discharge amount of the molten glass from the container. By these control mechanisms, the depth at the position where the glass raw material of the molten glass in the container is charged is 1.5 to 3 times the raw material charging height based on the liquid level of the molten glass, preferably 1.6 to The raw material supply amount and the molten glass discharge amount can be controlled so as to be 2.5 times, and the raw material can be melted before the introduced glass raw material reaches the bottom of the container. Thereby, the erosion of the container can be prevented, and substances constituting the container wall can be prevented from being mixed into the molten glass and contaminating the glass.

  In addition, it is desirable that the raw material charging mechanism has a system in which raw materials are continuously charged. By continuously charging the raw materials, the input amount of the raw materials can be made uniform over time, and a large amount of reducing substance can be prevented from being generated by decomposition at a time. An example of the continuous raw material charging mechanism is as follows. In order to keep the raw material in a dry state, it has a preliminary chamber filled with a dry atmosphere and a raw material supply passage connected to the raw material input port from the preliminary chamber, and a screw is provided in the preliminary chamber and the supply passage, and the screw is rotated at a constant speed By continuously rotating by the number, the raw material accumulated in the preliminary chamber is pushed out through the supply passage to the raw material charging port, and the raw material is continuously charged into the container through the charging port.

The said apparatus I can be used suitably also for manufacture of phosphate glass.
Next, the glass melting apparatus II will be described.

  In the glass melting apparatus II, as described in the manufacturing method II described above, since the inside of the container is filled with the dry atmosphere gas, moisture in the atmosphere can be reduced. In addition, since the atmospheric gas flows along with the glass raw material along the charging path to the molten glass liquid surface, even if the glass raw material slightly adsorbs moisture, it is introduced by mixing with the atmospheric gas. The amount of moisture adsorbed by the raw material can be reduced. After the atmospheric gas reaches the surface of the molten glass, the atmospheric gas is exhausted to the outside of the container, and the atmosphere in the container is kept in a dry state, so that the reaction between the molten glass and OH groups or moisture can be suppressed.

  In addition, since the atmospheric gas flows along the glass raw material input path, the gas generated from the molten glass reaches the glass raw material supply port, solidifies the glass raw material and closes the glass raw material supply port, It is possible to prevent the raw material supply port from being blocked by rising air.

  This apparatus II is suitable as an apparatus for obtaining a fluorophosphate glass by using a fluorine compound and a metaphosphate compound as raw materials, and in this case, as a dry atmosphere gas, a dry inert gas, a dry oxygen gas, Alternatively, it is preferable to supply a dry mixed gas of inert gas and oxygen gas.

Furthermore, it is desirable to provide an exhaust port heater for heating the atmospheric gas exhaust port in order to prevent the hardly soluble AlPO ₄ from coagulating from the container to the exhaust port of the atmospheric gas and clogging. AlPO ₄ is not solidified at the exhaust port heated by the heater, and is exhausted out of the container together with the atmospheric gas in a gaseous state. The portion for exhausting the atmospheric gas is preferably heated to 600 ° C. or higher.

  In this apparatus II, like the apparatus I described above, the raw material charging mechanism is preferably a continuous type. However, in order to prevent moisture from entering from the outside of the container as the raw material is supplied, It is preferable to provide a mechanism for adjusting the pressure of the dry atmosphere gas so as to be positive.

  In addition, the interior of the container is divided by a partition extending to the vicinity of the molten glass liquid surface so as to surround the raw material input path from the raw material input port, and the atmosphere gas exhaust port is provided in a portion separated from the raw material input port by this partition wall. Is desirable. By providing the partition wall in this way, the atmosphere in the container can be constantly replaced, and the atmospheric gas can be surely flowed along the predetermined flow path. Moreover, it is possible to prevent the charged raw material from being surely charged into the molten glass and discharged directly from the exhaust port.

The container preferably has a cylindrical shape, and preferably has a side surface provided with a heating unit for heating the molten glass stored in the container. Furthermore, the glass surface is maintained so that the liquid level of the molten glass with respect to the bottom surface of the container is maintained within a range of preferably 2.5 to 10 times, more preferably 3 to 6 times the inner diameter of the container. It is desirable to have a control mechanism that controls at least one of the input amount of raw material and the discharge amount of molten glass, and it has a control mechanism that controls both the input amount of glass raw material and the discharge amount of molten glass. More desirable. The feature of this apparatus is that the ratio of the area where the molten glass touches the atmospheric gas with respect to the volume of the molten glass in the container can be reduced, and the area where the molten glass contacts the container with respect to the volume of the molten glass can be mentioned. With these characteristics, the area where the molten glass comes into contact with the atmosphere can be reduced, the reaction with moisture and the volatilization amount of the glass component can be reduced, and the molten glass can be efficiently heated.

  If the liquid surface height of the molten glass with respect to the bottom surface of the container is less than 2.5 times the diameter of the bottom surface of the container, the above effect is difficult to obtain sufficiently, and if it exceeds 10 times, stable supply of atmospheric gas is possible. It becomes difficult to exhaust.

  The molten glass is sent to the clarification tank from the outlet of the container, clarified and stirred, and becomes a high-quality glass that is uniform and does not contain fine particles and bubbles that become a light scattering source. Since this glass is high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass.

  The apparatus II is not limited to the production of fluorophosphate glass, but can also be suitably used for the production of fluoride glass and boric acid-containing glass such as borosilicate glass.

  Further, in the melting apparatus II, an oxidizing gas supply port for supplying a dry oxidizing gas into the molten glass can be provided, and a raw material charging port can be disposed above the oxidizing gas supply port. Thus, by providing the structure of the melting apparatus I, the melting apparatus I has the characteristics. As described in the manufacturing method II described above, phosphate glass, fluoride glass, fluorophosphate glass, and borosilicate It can be used suitably for the production of boric acid-containing glass such as acid glass and also for the production of low-viscosity silicate glass.

  In addition, the glass melting apparatus I and II of this invention can connect with a melting apparatus as needed, and can provide a clarification tank and a stirring tank.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
FIG. 1 is a schematic vertical cross-sectional view of the glass melting apparatus of the present invention used in this example.

The container 10 for melting glass is a platinum cylindrical container having an inner diameter of 0.28 m and a height of 0.95 m.
In the upper center of the container 10, a raw material input port 5 for supplying a raw material into the container is provided, and a raw material input mechanism 1 and an atmospheric gas supply port 6 are provided so as to communicate with the raw material input port 5.

The raw material charging mechanism 1 includes a preliminary chamber 13 in which premixed raw materials are stored, a raw material supply passage 14 for supplying raw materials to the charging port 5, a screw 2 inserted through the raw material supply passage 14 and the preliminary chamber 13, A motor 3 for rotating the screw 2 and a control mechanism (not shown) for controlling the supply amount of the raw material are provided. The glass raw material stored in the preliminary chamber 13 is pushed out to the supply passage 14 by the screw 2 by driving the motor 3, passed through the raw material discharge port 4, and charged into the container 10 from the raw material charging port 5. The Since the supply amount of the raw material is determined by the rotation speed of the motor 3, the control mechanism can increase or decrease the supply amount of the raw material by increasing or decreasing the rotation speed of the motor 3. The preliminary chamber 13 is also provided with an atmospheric gas supply port 6 ′ for supplying a dry atmospheric gas. The atmospheric gas in the dry state is supplied from the atmospheric gas supply port 6 ′ together with the atmospheric gas supply port 6 to the container 10.

  A cylindrical partition wall 9 is provided at the center and upper part of the container 10 so as to surround the charging path of the glass raw material charged from the charging port 5. Further, an upper portion and a peripheral portion of the container 10 are provided with an atmosphere gas supply port 6, 6 ′, and a raw material input port 5 and an exhaust port 7 for exhausting the atmospheric gas that has passed through the inside of the container 10 are provided. Yes. The exhaust port 7 is provided with a heating device 8 so that glass vapor generated at the time of melting the glass cools and solidifies, and does not close the exhaust port. In addition, the partition wall 9 must have a length that does not hinder the flow of the atmospheric gas in a state where the molten glass is stored in the container 10.

  A heater (not shown) is provided on the outer surface of the container 10 in order to perform heating for melting the glass, and the molten glass is heated through the side surface of the container 10.

  A discharge port 12 for discharging the glass melted in the container is provided at the peripheral edge of the bottom of the container 10, and the molten glass discharged from the container 10 is sent to a clarification tank and clarified.

  A bubbling pipe 11 for supplying an oxidizing gas is provided at the center of the bottom of the container 10, from which dry oxygen gas is supplied to the molten glass, and bubbling with oxygen gas is performed. Yes.

  In the container 10 and the raw material input mechanism 1 connected to the container 10, air containing water vapor is externally supplied except for the atmospheric gas supplied from the atmospheric gas supply ports 6 and 6 ′ and the oxidizing gas supplied from the bubbling pipe 11. It is kept at a positive pressure so as not to penetrate.

  Using such a glass melting apparatus, the fluorophosphate glass was melted and manufactured. The container 10 stores molten glass heated to 800 to 1000 ° C., preferably 950 to 1000 ° C., by a heater provided on the outer surface of the container. Oxygen gas dried from the bubbling pipe 11 is supplied into the molten glass, and the central portion of the molten glass is bubbled with oxygen gas.

  In the preliminary chamber 13 of the raw material charging mechanism 1, a dry prepared glass raw material is put and dried from the atmosphere gas supply ports 6 and 6 '(dry oxygen gas, dry inert gas, or dry oxygen gas and dry inert gas). Gas mixture gas) is continuously supplied.

As the raw material of fluorophosphate glass, AlF ₃ , MgF ₂ , CaF ₂ , SrF ₂ , YF ₃ (hereinafter referred to as a fluorine compound), Al (PO ₃ ) ₃ , Mg (PO ₃ ) ₂ , Ca (PO ₃ ) ₂ , _{sr (PO 3) 2, Ba} (PO 3) 2 ( or, metaphosphate compound) was used to prepare a.

The atmospheric gas passes through the raw material inlet 5 and is guided to the partition wall 9 toward the molten glass liquid surface, passes between the partition wall 9 and the molten glass liquid surface, passes between the inner wall side surface of the container 10 and the partition wall 9, The air is exhausted from the exhaust port 7. In this manner, the container 3 is filled with the dry atmosphere gas, the motor 3 of the raw material charging mechanism 1 is rotated at a constant rotational speed, and the glass raw material in the preliminary chamber 13 is continuously charged at a constant supply amount. Extrude to 5. The glass raw material passes through the portion surrounded by the partition wall 9 from the inlet 5 and falls to the liquid surface in the center of the molten glass where oxygen gas is bubbled. At this time, since the atmospheric gas is flowing along the raw material charging path, the raw material is not lifted by the convection in the container 10 or the rising air current by the bubbling gas. Further, it is possible to prevent the glass vapor generated from the molten glass from adsorbing to the glass raw material and adhering to the raw material charging port and hindering the raw material charging.

  Of the charged glass raw material, the metaphosphate compound decomposes in the molten glass to produce free phosphorus having extremely strong reducibility, but is rapidly oxidized and melted by the oxygen gas bubbled in the molten glass. Therefore, the melting of the glass is efficiently performed, the metaphosphate compound and free phosphorus can be prevented from reaching the inner wall of the platinum container 10, and the container 10 can be prevented from being eroded. Accordingly, the platinum fine particles in the container 10 are not mixed into the molten glass.

  The atmospheric gas that travels from the molten glass liquid surface to the space between the inner wall side surface of the container 10 and the partition wall 9 contains glass vapor generated from the molten glass, but this vapor reacts with minute moisture to cause poorly soluble aluminum phosphate. It goes to the exhaust port 7 together with the atmospheric gas. Since the exhaust port 7 is heated, the aluminum phosphate does not solidify in the exhaust port 7, the flow of the atmospheric gas is not hindered, and the solidified aluminum phosphate does not fall into and mix with the molten glass. Problems such as foaming can also be avoided.

  The depth of the molten glass (the height of the molten glass liquid level measured from the center of the bottom of the container) is controlled by the control of the raw material input amount by the raw material supply amount control mechanism and the molten glass discharge amount by the molten glass discharge amount control mechanism. The height of the raw material inlet 5 with respect to the molten glass liquid surface is preferably kept 1.6 to 2.5 times. Therefore, the raw material charged from the raw material charging port 5 is melted before reaching the bottom of the container 10 and there is no possibility that the platinum on the inner surface of the container is corroded.

  Furthermore, by controlling the height of the molten glass liquid surface, the depth of the molten glass is preferably maintained at 3 to 6 times the inner diameter of the container 10, and the molten glass is not disturbed by obstructing the flow path of the atmospheric gas. The area in contact with the atmospheric gas per volume can be reduced.

  The molten glass obtained in the container 10 is sent from a discharge port 12 to a clarification tank (not shown) to be clarified, and becomes high-quality optical glass that does not contain impurities such as residual bubbles and platinum fine particles.

As described above, while continuously supplying the atmospheric gas and the bubbling gas, the glass raw material is continuously added to continuously produce high-quality optical glass containing no impurities such as platinum fine particles and bubbles with high productivity. I was able to.
Example 2
The same apparatus as that used in Example 1 was used, and borosilicate glass was melted in the same manner as in Example 1.

  A borosilicate raw material, a silicate raw material, and other raw materials are mixed and supplied to the raw material charging mechanism 1, and continuously fed into the molten glass from the raw material charging port 5 while flowing a dry atmosphere gas to obtain a borosilicate glass. It was. Also in this example, it was possible to continuously obtain high-quality optical glass free from bubbles and impurities with high productivity.

  By using the glass manufacturing method and glass melting apparatus of the present invention, it is possible to produce high-quality glass, particularly phosphate glass, fluoride glass, fluorophosphate glass, boric acid-containing glass, etc., using highly reactive raw materials. Can be manufactured well.

It is a vertical cross-sectional schematic diagram of the glass melting apparatus of this invention used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material injection mechanism 2 Screw 3 Motor 4 Raw material discharge port 5 Raw material supply port 6 Atmospheric gas supply port 6 'Atmospheric gas supply port 7 Exhaust port 8 Heating device 9 Bulkhead 10 Container 11 Bubbling pipe 12 Molten glass discharge port 13 Spare chamber 14 Raw material Supply passage

Claims (16)

A glass manufacturing method comprising a step of charging a molten glass in a heated container with the raw material of the glass and melting the glass, the inside of the container being filled with a dry atmospheric gas, and the dry atmospheric gas being converted into a glass raw material A glass raw material is charged while flowing to the molten glass liquid surface along the charging route. As glass raw materials, a fluorine compound and a metaphosphate compound, method for producing glass according to claim 1 for melting fluorophosphate glass.   The manufacturing method of the glass of Claim 1 which fuse | melts a boric-acid containing glass using a boric-acid compound as a glass raw material. With bubbling an oxidizing gas into molten glass, its bubbling position, method for producing glass according to any one of claims 1 to 3 charged glass raw material showing a reducing in the process of being melted. The method for producing glass according to claim 4 , wherein the glass raw material is introduced into a position where the bubbling gas springs out. Method for producing glass according to claim 2 using AlF ₃ as a raw material. Method for producing glass according to claim 3 boric San含Yuga lath is borosilicate glass. The method for producing glass according to any one of claims 1 to 7 , wherein the dry atmosphere gas is exhausted out of the container after reaching the molten glass liquid surface. The method for producing glass according to any one of claims 1 to 8 , wherein any one of a dry inert gas, a dry oxygen gas, and a dry mixed gas of an inert gas and an oxygen gas is used as the dry atmosphere gas. The method of producing glass according to any one of claims 1 to 9 for heating the exhaust port for exhausting the ambient gas from the vessel. The method for producing glass according to any one of claims 1 to 10 , wherein the inside of the container is maintained at a positive pressure with respect to the outside of the container by a dry atmosphere gas. The molten glass feed to refining tank from the discharge port of the container, clarified, stirred manufacturing method of a glass according to any one of claims 1 to 11, to obtain an optical glass. A glass melting apparatus for charging a glass raw material to obtain molten glass by heating and melting, the glass raw material being heated and melted, and a container for storing the obtained molten glass, and a container connected to the container. a raw material inlet, a dry ambient gas supplying dry ambient gas supply port satisfying the vessel, cut the atmospheric gas exhaust port for exhausting the囲気gas, comprising as main components, and the glass raw material from the dry ambient gas supply port A glass melting apparatus characterized in that the interior of the container is divided so as to form a flow path of an atmospheric gas that leads to a molten glass liquid surface along an input path and reaches an exhaust port. The heating unit for heating the molten glass from the side surface of the container having a cylindrical shape and the height of the liquid surface of the molten glass with respect to the bottom surface of the container are maintained within a range of 2.5 to 10 times the inner diameter of the container. The glass melting apparatus of Claim 13 provided with the control mechanism which controls the input amount of a glass raw material, and / or the discharge amount of molten glass so that it may lean. The glass melting apparatus of Claim 13 or 14 provided with the oxidizing gas supply port which supplies the oxidizing gas dried in the molten glass, and the raw material input port is arrange | positioned above the oxidizing gas supply port. The glass melting apparatus according to any one of claims 13 to 15 , wherein the container has a cylindrical shape, and a heating unit for heating the molten glass stored in the container is attached to a side surface of the container.

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