JP6520358B2 - METHOD FOR PRODUCING GLASS SOURCE GRANULATED BODY, METHOD FOR PRODUCING MOLTEN GLASS, AND METHOD FOR PRODUCING GLASS ARTICLE - Google Patents

Description

  The present invention relates to a method of producing a glass material granule, a method of producing molten glass using the glass material granule, and a method of producing a glass article.

  In the production of glass, if the raw material powder is scattered when the raw material powder is put into the melting furnace, the raw material powder is granulated because problems such as a decrease in the homogeneity of the glass composition and a problem of waste of the raw material occur. Methods have been proposed.

  In Patent Document 1 below, boric acid, sodium hydroxide, calcium chloride and a combination of calcium chloride and boric acid, or a combination of boric acid and a polyhydric alcohol are used as a binder when granulating glass material powder. It is described. In the example of producing granules with boric acid as a binder, it is described that a glass batch material containing 0.3% by weight or 17.2% by weight of aluminum hydroxide is used, but aluminum hydroxide and There is no mention of using an alkali metal hydroxide in combination.

  According to Patent Document 2 below, water-soluble silicates such as sodium metasilicate and sodium disilicate are formed by reacting silica sand and caustic soda (sodium hydroxide) in advance under high temperature, and the silicate Describes a method for producing a granulated body by using In this method, the water-soluble silicate-generated sand is mechanically treated to at least partially remove the water-soluble silicate from the sand, and thereafter, the remaining raw material components are mixed to obtain water. Add and granulate. As the remaining raw material components, feldspar, natural silicate, lead silicate, alumina (aluminum oxide), borax or boric acid, lithium-containing mineral, lithium carbonate, potassium hydroxide, magnesite, barium carbonate and zinc oxide are described. It is done. The use of aluminum hydroxide is not described.

Japanese Patent Application Laid-Open No. 56-14427 Japanese Patent Publication No. 56-37176

However, in the method described in Patent Document 1, the strength of the granulated body may be low and it may be easily broken.
Although the method described in Patent Document 2 can produce granules with high strength, due to the use of a large amount of caustic soda, aggregation is likely to occur during the preparation of granules, and the particle diameter controllability is low, and uniform granules are obtained. The process is complicated and complicated because it is difficult to obtain and it is necessary to process the sand grains mechanically after reacting the silica sand and caustic soda (sodium hydroxide). In addition, since a large amount of highly reactive caustic soda is used, there is a problem that the apparatus and equipment are easily corroded.

  The present invention provides a method capable of producing a glass raw material granule having high strength and being resistant to breakage by using aluminum hydroxide and an alkali metal hydroxide, without using a large amount of highly reactive caustic soda. .

The present invention is as follows.
[1] A method for producing a glass raw material granule from a glass raw material composition containing at least silica, an aluminum source, an alkali metal source, and boric acid, which comprises 40 to 40 parts of silica in terms of solid content. Water of glass raw material composition (A) containing 75% by mass, 3 to 30% by mass of aluminum hydroxide, 3 to 30% by mass of boric acid, and 0.4 to 4.6% by mass of alkali metal hydroxide A method for producing a glass material granule, comprising the step of granulating in the presence of

[2] The method for producing a glass material granule according to [1], wherein D50 representing the average particle diameter of the silica is 5 to 350 μm.
[3] The glass raw material granulation according to [1], wherein D50 representing the average particle diameter of the silica is 200 to 350 μm, and the content of the alkali metal hydroxide is 0.4 to 2.1 mass%. How to make the body.
[4] The glass raw material granulation according to [1], wherein D50 representing the average particle diameter of the silica is 5 to 50 μm, and the content of the alkali metal hydroxide is 0.8 to 4.2 mass%. How to make the body.

[5] The composition of the glass obtained from the granulated body is mass% display based on oxide, the content of SiO ₂ is 50 to 75 mass%, the content of Al ₂ O ₃ is 3 to 30 mass%, B ₂ The content of O ₃ is 1 to 20% by mass, the total content of Li ₂ O, Na ₂ O and K ₂ O is 10 to 20% by mass, and the total content of MgO, CaO, SrO and BaO is 0 to 0 The manufacturing method of the glass raw material granulated body as described in any one of [1]-[4] which is 25 mass%.
[6] The method for producing a glass material granule according to any one of [1] to [5], wherein D50 representing the average particle diameter of the aluminum hydroxide is 1 μm to 120 μm.
[7] The method for producing a glass material granule according to any one of [1] to [6], wherein the alkali metal hydroxide contains sodium hydroxide.
[8] The method for producing a glass material granule according to any one of [1] to [7], wherein D50 representing the average particle diameter of the glass material granule is 412 μm to 2 mm.
[9] The method for producing a glass material granule according to any one of [1] to [8], wherein the glass material granule is granulated by a rolling granulation method.

[10] A process for producing a glass material granule by the method according to any one of [1] to [9], and a glass melting process for heating the obtained glass material granule to obtain molten glass A method of producing molten glass, comprising:
[11] The method for producing molten glass according to [10], wherein the glass melting step includes the step of charging the glass raw material granulated body on a molten glass liquid surface in a melting furnace.
[12] The glass melting step includes the steps of melting the glass raw material granule in a gas phase atmosphere to form molten glass particles, and collecting the molten glass particles to form molten glass. The manufacturing method of the molten glass as described in [10].
[13] A method for producing a glass article using the method for producing molten glass according to any one of [10] to [12], wherein the glass melting step and the obtained molten glass are formed. A manufacturing method of a glass article which has a forming process and a slow cooling process of slow cooling the glass after forming.

According to the present invention, good glass raw material granules can be obtained without complicating the process by using aluminum hydroxide and an alkali metal hydroxide, without using a large amount of highly reactive caustic soda. It can be manufactured.
According to the method for producing molten glass of the present invention, a good granulated body can be produced without complicating the production process of the glass raw material granulated body, and a molten glass can be produced using the granulated body.
According to the method for producing a glass article of the present invention, a good granulated body can be produced without complicating the production process of the glass material granulated body, and a glass article can be produced using the granulated body.

In the present specification, the components of the glass are represented by oxides such as SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ and Na ₂ O. Content (glass composition) of each component with respect to the whole glass is represented by the mass percentage of an oxide basis on the basis of 100% of mass of glass.
In the present specification, “glass raw material” is a raw material to be a component of glass, and “glass raw material composition” is a composition containing a plurality of glass raw materials. Examples of the glass raw material include oxides, complex oxides, and compounds that can be converted to oxides by thermal decomposition. Examples of the compound that can be converted to an oxide by thermal decomposition include hydroxides, carbonates, nitrates, sulfates, and halides. In the present specification, the "granulate" is obtained by granulating a glass material composition.
In the present specification, the composition of the glass raw material composition is represented by mass% in terms of solid content. That is, the solid content mass of the glass raw material composition is represented by mass percentage assuming that it is 100% by mass, and when the glass raw material composition contains an aqueous solution, the composition includes the solid content in the aqueous solution. In addition, solid content contains crystal water.
In the present specification, "D50" is an average particle size represented by 50% diameter in integrated fraction. D50 of the glass material is a 50% diameter at a volume-based integrated fraction measured using a laser diffraction method. As a particle diameter measuring method by a laser diffraction method, the method described in JIS Z 8825-1 (2001) is used.
The D50 of the granulated body is a median diameter of 50% cumulative mass measured using a sieve or the like.

<Glass raw material composition (A)>
The glass material composition (A) contains at least silica, an aluminum source, boric acid and an alkali metal source.
[silica]
Silica is a compound that becomes an SiO ₂ component that is a glass network former in the glass manufacturing process and is essential.
The silica includes silica sand, quartz, cristobalite, and amorphous silica. These may be used alone or in combination of two or more. Silica sand is preferred because it is easy to obtain high quality raw materials. These are used in powder form.
The content of silica relative to the glass raw material composition (A) is 40 to 75% by mass, preferably 45 to 72% by mass, and more preferably 50 to 70% by mass. If the content of silica is 40% by mass or more, the granules are difficult to adhere to the wall surface and the like of the granulator, and thus they are easy to handle. The content of silica sand is more preferably 45% or more, and still more preferably 50% or more from the viewpoint that the granules are less likely to adhere. When the content of silica is 75% by mass or less, the strength of the granulated body tends to be high. As for content of a silica, 72 mass% or less is more preferable, and 70 mass% or less is more preferable at the point which a granulated body does not collapse easily.
The D50 of silica is preferably 5 to 350 μm. When the D50 of silica is 5 μm or more, the powder is easy to handle in the granulation step and easily granulated. If it is 350 μm or less, a homogeneous granulated body is easily obtained. Moreover, if D50 of silica is 200-350 micrometers, it will be easy to utilize the powder raw material with few impurities, such as iron, and it will be easy to control the composition of a granulated body. When the D50 of silica is 5 to 50 μm, the silica is sufficiently small compared to the granule, and thus the silica is easily dispersed uniformly in the granule, and thus a more homogeneous granule can be stably obtained. preferable.

[Aluminum source]
The aluminum source is a compound to be an Al ₂ O ₃ component in the process of producing molten glass. Al ₂ O ₃ is a component having an effect such as stabilizing the glass, and in the aluminosilicate glass, it is an essential component.
Examples of the aluminum source include aluminum oxide, aluminum hydroxide, feldspar and the like. In the present invention, at least aluminum hydroxide is used to increase the strength of the granules, but one or more other aluminum sources may be used in combination. These are preferably in the form of powder.
Aluminum hydroxide exhibits a binder effect to bind the raw material powder when used in combination with an alkali metal hydroxide. At this time, the D50 of aluminum hydroxide is preferably 1 to 120 μm, more preferably 2 to 60 μm, and still more preferably 3 to 30 μm. It is easy to handle when the D50 of aluminum hydroxide is at least the lower limit value of the above range, and a uniform granulated body is easily obtained when it is at the upper limit value of the above range. As for D50 of aluminum hydroxide, 5 to 20 μm is particularly preferable because the strength of the granules can be increased.

The content of aluminum hydroxide is 3% by mass or more, preferably 5% by mass or more, and more preferably 10% by mass or more based on the solid content of the glass raw material composition (A). A favorable granulated body is obtained as content of aluminum hydroxide is 3 mass% or more.
The upper limit value of the content of aluminum hydroxide to the glass raw material composition (A) is determined according to the glass composition to be obtained. For example, 30 mass% or less is preferable with respect to a glass raw material composition (A), and 25 mass% or less is more preferable.
13-100 mass% is preferable, and, as for the ratio of aluminum hydroxide with respect to the sum total of an aluminum source, 20-100 mass% is more preferable.
[Boric acid]
Although content of boric acid can be suitably set with desired glass composition with respect to solid content of the glass-making feedstock composition (A) in this invention, 3-30 mass% is preferable. If it is 3 mass% or more, it will be easy to melt | dissolve. If the content of boric acid is 30% by mass or less, it is preferable because the glass strength can be easily increased. At this time, the content of boric acid may be determined in consideration of the amount of volatilization and reduction in the high temperature glass manufacturing process.
Examples of boric acid include orthoboric acid (H ₃ BO ₃ ), metaboric acid (HBO ₂ ), tetraboric acid (H ₂ B ₄ O ₇ ) and the like. Among these, orthoboric acid is preferable in terms of inexpensiveness and availability. These may be used alone or in combination of two or more.
Alternatively, boric acid and a boron source other than boric acid may be used in combination. Examples of boron sources other than boric acid include boric acid oxide (B ₂ O ₃ ), colemanite and the like.
The total amount of boron source in the glass raw material depends on the glass composition to be obtained. When the total amount of boron sources is 100% by mass, the proportion of boric acid is preferably 60% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass.

[Alkali metal source]
The alkali metals in the present invention refer to Na, K and Li. The alkali metal source is a compound to be a Na ₂ O, K ₂ O or Li ₂ O component in the process of producing a molten glass. Examples of the alkali metal source include carbonates, sulfates, nitrates, oxides, hydroxides, chlorides and fluorides of alkali metals. These may be used alone or in combination of two or more. Sulfates, chlorides and fluorides of alkali metals can act as fining agents.

In the present invention, at least an alkali metal hydroxide is used to facilitate granulation. The alkali metal hydroxide may be used in the form of powder or granules or in the form of an aqueous solution. The content of the alkali metal hydroxide can be changed according to the particle size and surface area of the other raw materials.
The content of the alkali metal hydroxide is 0.4 to 4.6% by mass, 1.0 to 3.5% by mass with respect to the glass raw material composition (A) having a D50 of silica of 5 to 350 μm. More preferable. Content of an alkali metal hydroxide is 0.4-2.1 mass% with respect to the glass raw material composition (A) whose D50 of silica is 200-350 micrometers, 0.8-1.6 mass% More preferable. The content of the alkali metal hydroxide is 0.8 to 4.2% by mass, and 2.2 to 3.6% by mass with respect to the glass raw material composition (A) in which D50 of silica is 5 to 50 μm. More preferable.
A favorable granulated body is obtained as it is said range. The alkali metal hydroxide, when used in combination with aluminum hydroxide, exerts a binder effect to bind the raw powder of aluminum hydroxide. If the content of the alkali metal hydroxide is too small, grain growth tends to be insufficient in the granulation step. When the content of the alkali metal hydroxide is too large, the granulated body is apt to be agglomerated, to be easily attached to the device or instrument, and to be easily corroded. The optimum value of the content of alkali metal hydroxide is determined by the surface area of the silica to be mixed, and if the average particle size (D50) of silica is smaller than 50 μm, the surface area of silica in the raw material becomes large. If the average particle size of the silica is larger than 200 μm, the surface area of the silica in the raw material becomes small, so the above-mentioned range is preferable.
4-29 mass% is preferable, and, as for the ratio of alkali metal hydroxides, such as caustic soda, with respect to the sum total of an alkali metal source, 8-26 mass% is more preferable. If the proportion of the alkali metal hydroxide is too small, grain growth tends to be insufficient in the granulation step. When the proportion of the alkali metal hydroxide is too large, the granulated body tends to be sticky and clumps, to be easily attached to the device or instrument, and the device or instrument is easily corroded.
As the alkali metal hydroxide, sodium hydroxide is preferable in terms of availability. The sodium hydroxide is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 100% by mass with respect to the total of the alkali metal hydroxides to be contained in the glass raw material composition (A).

In order to prevent aggregation of the granules, it is preferable to use an alkali metal carbonate in addition to the alkali metal hydroxide. For example, sodium carbonate, potassium carbonate and lithium carbonate are preferred, and sodium carbonate (soda ash) is particularly preferred in view of ease of handling.
The content of the alkali metal carbonate in the glass raw material composition (A) is preferably 30% by mass or less in terms of solid content, because the strength of the granulated body can be increased.
Although D50 of an alkali metal carbonate is not specifically limited, 50-400 micrometers is preferable and 55-120 micrometers is more preferable. It is easy to granulate that D50 of an alkali metal carbonate is in the above range, and a homogeneous granulated body is easily obtained.
When using an alkali metal carbonate, 5-30 mass% is preferable, and, as for content of the sum total of alkali metal carbonate in glass-making feedstock composition (A), 10-26 mass% is more preferable.

[Alkaline earth metal source]
The glass raw material composition (A) can contain an alkaline earth metal source in addition to the above components.
The alkaline earth metals in the present specification refer to Mg, Ca, Ba and Sr. The alkaline earth metal source is a compound that forms MgO, CaO, BaO, SrO in the process of producing molten glass. The alkaline earth metal source includes carbonates, sulfates, nitrates, oxides, hydroxides, chlorides and fluorides of alkaline earth metals. These may be used alone or in combination of two or more. The alkaline earth metal source is preferably a powder. Alkaline earth metal sulfates, chlorides and fluorides may act as fining agents.
Also, composite carbonates such as dolomite and composite oxides such as calcined dolomite can be used.

It is preferred to use an alkaline earth metal oxide or an alkaline earth metal hydroxide as the alkaline earth metal source.
When an alkaline earth metal source is used, the content of the alkaline earth metal source is preferably 2 to 13% by mass, and more preferably 5 to 9% by mass, with respect to the glass raw material composition (A). It is easy to obtain a high strength granulated body in the above range.

[Other glass materials]
Glass raw material composition (A) can contain other compounds known as glass raw materials as long as the effects of the present invention are not impaired. Other compounds include tin oxide, titanium oxide, zirconium oxide, zircon, cerium oxide, antimony oxide, iron oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide and the like. These may be used alone or in combination of two or more. In order to obtain high strength and homogeneous granules, the total content of the other compounds is preferably 20% by mass or less, more preferably 10% by mass or less.
Iron oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide and the like are used as a colorant. Antimony oxide, tin oxide, etc. may be used as a fining agent. These may be used alone or in combination of two or more.

[Composition of glass raw material composition (A)]
The composition of the glass raw material composition (A) is adjusted so as to be substantially the same as the composition of the target glass article in terms of oxide, except for components that are easily volatilized in the glass melting step. Boric acid is preferably added in excess since it is easily volatilized in the glass melting step.
As shown in the following production example of a granulated body, the glass raw material composition (A) contains silica, aluminum hydroxide, boric acid, and an alkali metal hydroxide in a predetermined ratio to obtain the glass. Granules having good strength can be produced by a method of granulating the raw material composition (A) in the presence of water.
When the value of D50 of silica is x (unit: μm, 5 ≦ x ≦ 350) and the content of alkali metal hydroxide is y (unit: mass%, 0.4 ≦ y ≦ 4.6) In the range satisfying y ≦ 4.6-0.0071x, aggregation of the granules is well suppressed.
In particular, the D50 of silica is 200 to 350 μm, and the content of the alkali metal hydroxide is in the range of 0.4 to 2.1% by mass, or the D50 of silica is 5 to 50 μm, and alkali metal hydroxide The content of the substance is preferably in the range of 0.8 to 4.2% by mass. If it is the range, since y <= 4.6-0.0071x is satisfied, aggregation of granules is suppressed and it is easy to be able to obtain a uniform granule.
The reason why a granulated body having good strength can be obtained by the production method of the present invention is not clear, but in the granulation step, the reaction between an alkali metal hydroxide and aluminum hydroxide in the presence of water causes aluminization. It is thought that an acid ion is generated, which reacts with Si-OH on the silica surface to develop water-hardening properties.

The composition of the glass raw material composition (A) other than silica, aluminum hydroxide, boric acid, and alkali metal hydroxide is not particularly limited, and can be set according to the composition of the target glass article.
If the content of the phosphorus oxide in the glass raw material composition (A) is small, it is preferable in that a homogeneous granulated body is easily obtained. When the content of phosphorus oxide is large, the glass raw material may be rapidly aggregated. In the composition of the glass obtained from the glass raw material composition (A), the content of P ₂ O ₅ is preferably 3% by mass or less, more preferably 0.5% by mass or less, and P ₂ O ₅ other than unavoidable impurities It is particularly preferred not to contain

For example, it is preferable that the composition of the glass obtained from a granulated body is the following.
The content of SiO ₂ is 50 to 75% by mass,
The content of Al ₂ O ₃ is 3 to 30% by mass,
The content of B ₂ O ₃ is 1 to 20% by mass,
The total content of Li ₂ O, Na ₂ O and K ₂ O is 10 to 20% by mass,
The total content of MgO, CaO, SrO and BaO is 0 to 25% by mass.

In the composition of the glass obtained from the granules,
The content of SiO ₂ is more preferably 60 to 70 wt%.
The content of Al ₂ O _3, more preferably 9 to 20 mass%.
The content of B ₂ O ₃ is more preferably 1 to 15% by mass.
The total content of Li ₂ O, Na ₂ O, and K ₂ O is more preferably 11 to 19% by mass.
The total content of MgO, CaO, SrO, and BaO is more preferably 0 to 15% by mass.
The total content of ZrO ₂ and TiO ₂ is more preferably 0 to 4% by mass.
Content of Fe ₂ O _3, and more preferably 0-9 wt%.
The content of Co ₃ O ₄ is more preferably 0-2 wt%.

[Particle diameter of granulated body]
The average particle size (D50) of the granulated body is not particularly limited, but is preferably 412 μm or more, and more preferably 500 μm or more in terms of preventing scattering of the raw material. Moreover, in the point which is easy to melt | dissolve rapidly, 2 mm or less is preferable, and 1.5 mm or less is more preferable.
It is preferable to select the suitable magnitude | size in said range by the method of manufacturing molten glass using this granulated body about the magnitude | size of a granulated body.
When the granulated body is used in a method of melting by a melting method not by air melting method described later, the generation of air bubbles in the molten glass is suppressed if the average particle diameter (D50) of the granulated body is 1 mm or more It is easy to be
When the granulated body is melted by an in-air melting method, the average particle diameter (D50) of the granulated body is preferably 1000 μm or less, more preferably 800 μm or less. The average particle diameter of the granulated body is preferably 1000 μm or less because vitrification proceeds sufficiently to the inside of the granulated body when it is melted in the air heating apparatus.

<Method of producing granulated body>
The method for producing a granulated body of the present invention has a granulating step of granulating the glass material composition (A) in the presence of water. It is preferable to further have a heating and drying step of heating and drying, if necessary.
As a method of supplying water to the glass material composition (A), a method of adding a part of the glass material composition (A) in an aqueous solution may be used.
The granulation step can be carried out using a known granulation method as appropriate. For example, a rolling granulation method, a stirring granulation method, a compression granulation method, a spray dry granulation method, or a method of crushing a compact obtained by compression molding is suitably used. The rolling granulation method is preferred in that it is easy to produce a homogeneous granulated body having a relatively small particle size.

[Rolling granulation method]
In the tumbling granulation method, the particles roll on the wall surface etc. by rotating the container containing the raw material obtained by adding water and binder to the powder, and other particles adhere around the core particles. It is a granulation method to grow grains. Stirring blades and a chopper can be provided in the rolling granulation container. The overgrown granulate is crushed by a stirring blade or a chopper to obtain an appropriately sized granulate.
As the rolling granulation method, for example, the powder of the glass raw material composition (A) is put in the container of the rolling granulation apparatus, and the raw material powder is mixed and stirred by vibrating and / or rotating the container. On the other hand, a method of granulating by spraying a predetermined amount of water on the raw material powder is preferable.
As a container of a rolling granulation apparatus, a dish shape, a cylindrical shape, a conical rotating container, a vibration type container, etc. can be used, It does not specifically limit.
The rolling granulation apparatus is not particularly limited, and, for example, a container that rotates about a direction inclined with respect to the vertical direction as a rotation axis, and a rotary wing that rotates in the container about the rotation axis in a direction opposite to the container A thing provided can be used. Specific examples of such a rolling granulation apparatus include Eirich Intensive Mixer (trade name: manufactured by Nippon Eirich Co., Ltd.).
There is no particular limitation on the order in which the glass raw materials are charged into the apparatus, but after the powder containing silica and aluminum hydroxide is premixed, a sodium hydroxide aqueous solution is added, or granular sodium hydroxide and water are added. Is preferred in that it can prevent local aggregation.

When the amount of water used is too large, it takes a long time to dry, but when it is too small, the strength of the granules is insufficient, so it is preferable to set so that these problems do not occur.
For example, the amount of water present at the time of granulation is preferably 5 to 25 parts by mass, and more preferably 6 to 20 parts by mass with respect to a total of 100 parts by mass of the solid content of the glass raw material composition (A).
If the amount of water relative to the solid content of the glass material composition (A) is insufficient, it is difficult to obtain a strong granulated body, and if it is excessive, it tends to adhere to the surface of an apparatus such as a mixer during mixing.
The particle size of the granulate can be controlled by the strength of the stirring and the stirring time.
After granulation with a tumbling granulator, it is preferable to heat and dry the obtained particles. It can carry out by a well-known heat-drying method. For example, a method of heating at a temperature of 100 ° C. to 200 ° C. for 1 hour to 12 hours using a hot air dryer can be used.

[Spray dry granulation method]
The spray dry granulation method can be performed by a known method. For example, using a stirring apparatus such as a ball mill, the glass raw material composition (A) and water are supplied to prepare a slurry, and the slurry is subjected to spraying using a spray dryer or the like, for example, a high temperature atmosphere of about 200 to 500 ° C. Granules are obtained by spraying in and drying and solidifying.
60-400 mass parts is preferable with respect to 100 mass parts of solid content, and, as for the quantity of the water in a slurry, 100-200 mass parts is more preferable.

<Method of producing molten glass>
The method for producing a molten glass of the present invention has a glass melting step (hereinafter, also referred to as a melting step) in which the granulated body obtained in the present invention is heated to form molten glass. The melting step may be performed using a crucible crucible or a Siemens type glass melting furnace or the like, or may be performed by electric melting. All can be implemented by a well-known method.
[Melting process]
In the melting step, when there is molten glass already melted in the glass melting furnace, the granulated body is put on the liquid surface, and the granulated body is lumped (also referred to as batch pile, batch pile). The product is heated by a burner or the like to advance melting from the surface of the lump to gradually make it into molten glass.
Alternatively, the granulated body is put into the raw material layer formed on the molten glass liquid surface, and melting is progressed from the part in contact with the molten glass heated by electric melting or the like to make it gradually into a molten glass.
In the case of producing a large amount of glass using a large apparatus, etc., mixing and charging of a raw material batch and a cullet obtained by crushing a glass plate or the like is performed. Since the granulated body of the present invention has high strength, it is preferable because the raw material batch consisting of the granulated body of the present invention and cullet are mixed and charged, and thus they are not easily broken.

[Atmospheric melting method]
The method for producing molten glass of the present invention may have the steps of: converting the granulated body of the present invention into molten glass particles by an air-melting method; and collecting the molten glass particles to obtain molten glass.
Specifically, first, the granulated body is introduced into the high temperature gas phase atmosphere of the atmospheric heating device. The air heater can be a known one. Since the granulated body of the present invention is excellent in strength, the generation of fine powder can be suppressed even when collisions between particles or particles and the inner wall of the transport path occur during transport or introduction.
Next, molten glass particles melted in the air heating apparatus are accumulated to obtain a glass melt, and the molten glass taken out therefrom is subjected to the next forming step. As a method of accumulating the molten glass particles, for example, a method of receiving and accumulating the molten glass particles falling in the gas phase atmosphere by their own weight in a heat resistant container provided in the lower part of the gas phase atmosphere can be mentioned.

<Method of producing glass article>
The method for producing a glass article according to the present invention is a method for producing a glass article by using the method for producing a molten glass according to the present invention.
First, the molten glass obtained in the melting step is formed into a target shape in the forming step, and then gradually cooled in the slow cooling step as necessary. Then, a glass article is obtained by giving post-processing by publicly known methods, such as cutting and polish, in a post-processing process as needed.
When the glass article is plate-like, the glass article is obtained by forming it into a desired shape by a known method such as a float method, down draw method, fusion method etc. and then performing slow cooling as necessary. Be

  The invention will be described in more detail by means of the following examples, but the invention is not limited thereto. Examples 1 to 3 are Examples, and Example 4 is a Comparative Example.

<Production example>
[Formulation of glass raw materials]
Calculated value of oxide conversion (unit: mass%) SiO ₂ 60.0%, Al ₂ O ₃ 19.8%, Na ₂ O 12.9%, B ₂ O ₃ 5.5%, Four formulations of Examples 1 to 4 shown in Table 1 were carried out to obtain a glass having a ZrO ₂ content of 1.8%. The composition shown in the table is the composition (mass%) in terms of solid content of the glass material composition (A). In the following formulation examples, all powder raw materials were used except that sodium hydroxide solution was used as sodium hydroxide, so the composition (mass%) shown in the table is based on the solid content of sodium hydroxide contained in sodium hydroxide solution It is the calculated value (unit: mass%) of calculated solid conversion.
Table 1 also shows values represented by 4.6 to 0.0071 x, where x (μm) is the value of D50 of silica (silica sand).
As the silica sand, three kinds of D50 of 13.1 μm, 36.8 μm and 292.7 μm were used.

D50 of other raw material powder is as follows.
D50 of boric acid (granular): 324 μm
Aluminum hydroxide D50: 7 μm,
D50 of aluminum oxide: 7 μm,
Sodium carbonate D50: 83 μm,
D50 of zircon (ZrSiO ₄ ): 12 μm.

[Manufacture of granulated body]
The granulated material was manufactured using the glass raw material composition (A) of the mixing | blending shown to the glass raw material composition column of Table 1 on the manufacturing conditions shown to a table | surface.
As the granulator, Eirich intensive mixer (product name, manufactured by Nippon Eirich, model: R02 type, volume 5 L, rotor: star type) was used.
In Table 1, a sodium hydroxide solution having a concentration of 48% by mass (hereinafter referred to as 48% aqueous sodium hydroxide solution) was used.
The formulations in Table 1 are indicated in parts by mass relative to a total of 100 parts by mass of the solid content (including the solid content in the aqueous sodium hydroxide solution) of the glass raw material composition (A). Water includes the dilution water contained in 48% aqueous sodium hydroxide solution.

(Example 1)
A mixture of 304 g of water and 195.2 g of a 48% aqueous solution of sodium hydroxide (hereinafter, referred to as sodium hydroxide-containing diluent) was prepared in advance to 499.2 g.
Among the formulations shown in Table 1, 2925.4 g of a powdery raw material excluding sodium hydroxide was charged into a granulator, and premixed for 60 seconds at a pan rotation speed of 42 rpm and a rotor rotation speed of 900 rpm. After pre-mixing, 235 g of a sodium hydroxide-containing diluted solution was charged while maintaining a pan rotation speed of 42 rpm. Thereafter, the rotor was rotated at 3000 rpm and granulated for 12 minutes, then taken out of the granulator and dried in a tray dryer under conditions of a temperature of 120 ° C. in a heating chamber for 15 hours to obtain a granulated body.

The particle size distribution and the average particle diameter (D50) of the obtained granules were measured using an automatic sieving measuring device (product name: Robot Shifter, RPS-105, manufactured by Seishin Enterprise Co., Ltd.). The measurement results of D50 are shown in the table. When D50 is too small, it means that grain growth is insufficient. When D50 is too large, it means that aggregation of grains occurred.
In addition, shake 15 g of the obtained granulated body with a shaker (product name: AS-1N) for 60 minutes (simulated fracture test), and then use an automatic sieving measuring device to measure the content of fine powder less than 106 μm (Unit: mass%) was measured. The results are shown in the table. The lower the fine particle rate, the higher the strength of the granulated body.
In the table, from the results of the fine powder ratio (simulated destruction test) after granulation and shake, the granulated material is regarded as “o”, and the granular material ratio is 2.0 mass% or less Granulation strength made "x" the thing whose intensity | strength of "O" and larger than 2.0 mass%. Moreover, particle diameter control property made "D" of 300 micrometers-1300 micrometers the particle diameter control property "(circle)", and particle diameter control property made "x" the particle | grains smaller than 300 micrometers or larger than 1300 micrometers.

(Example 2 to Example 4)
Granules were produced in the same manner as in Example 1 except that the production conditions were changed as shown in Table 1. The obtained granulated body was measured and evaluated in the same manner as in Example 1. The results are shown in the table.

  Granulation was possible in any of Examples 1 to 4. In Examples 1 to 3, granules having a low fine powder ratio and good strength were obtained. On the other hand, in Example 4 which did not contain aluminum hydroxide, aggregation was likely to occur during the production of the granules, and it was difficult to obtain uniform granules with low particle diameter controllability. In addition, the strength of the obtained granulated body was low and it was easily broken.

Claims (13)

A method of producing a glass material granule from a glass material composition containing at least silica, an aluminum source, an alkali metal source, and boric acid,
It contains 40 to 75% by mass of silica, 3 to 30% by mass of aluminum hydroxide, 3 to 30% by mass of boric acid, and 0.4 to 4.6% by mass of alkali metal hydroxide in terms of solid content. The manufacturing method of a glass-material granulated body which has the process of granulating glass-material composition (A) in presence of water.   The manufacturing method of the glass raw material granulated body of Claim 1 whose D50 showing the average particle diameter of the said silica is 5-350 micrometers.   The manufacturing of the glass raw material granulated body of Claim 1 whose D50 which represents the average particle diameter of the said silica is 200-350 micrometers, and content of the said alkali metal hydroxide is 0.4-2.1 mass%. Method.   The manufacturing of the glass raw material granulated body of Claim 1 whose D50 showing the average particle diameter of the said silica is 5-50 micrometers, and content of the said alkali metal hydroxide is 0.8-4.2 mass%. Method. The composition of the glass obtained from the granulated body is represented by mass% based on oxide,
The content of SiO ₂ is 50 to 75% by mass,
The content of Al ₂ O ₃ is 3 to 30% by mass,
The content of B ₂ O ₃ is 1 to 20% by mass,
The total content of Li ₂ O, Na ₂ O and K ₂ O is 10 to 20% by mass,
The total content of MgO, CaO, SrO and BaO is 0 to 25% by mass
The manufacturing method of the glass raw material granulated body as described in any one of Claims 1-4.   D50 which represents the average particle diameter of the said aluminum hydroxide is 1 micrometer-120 micrometers, The manufacturing method of the glass raw material granulated body as described in any one of Claims 1-5.   The manufacturing method of the glass raw material granulated body as described in any one of Claims 1-6 in which the said alkali metal hydroxide contains sodium hydroxide.   The manufacturing method of the glass raw material granulated body as described in any one of Claims 1-7 whose D50 showing the average particle diameter of a glass raw material granulated body is 412 micrometers-2 mm.   The method for producing a glass material granule according to any one of claims 1 to 8, wherein the glass material granule is granulated by a rolling granulation method.   A molten glass having a step of producing a glass raw material granule by the method according to any one of claims 1 to 9, and a glass melting step of heating the obtained glass raw material granule to make molten glass. Manufacturing method.   The method for producing molten glass according to claim 10, wherein the glass melting step comprises a step of charging the glass material granulated body on a molten glass liquid surface in a melting furnace.   The glass melting step includes the steps of melting the glass raw material granules in a gas phase atmosphere to form molten glass particles, and accumulating the molten glass particles to form molten glass. The manufacturing method of the molten glass as described. A method of producing a glass article using the method of producing molten glass according to any one of claims 10 to 12,
The manufacturing method of the glass article which has the said glass melting process, the formation process which shape | molds the obtained molten glass, and the slow cooling process which carries out the slow cooling of the glass after shaping | molding.