Manufacturing methods for glass products

Abstract

This invention relates to a method for manufacturing glass articles. The invention provides a method for manufacturing glass articles using a glass raw material composition comprising a dealkalizing agent separated from calcined products containing alumina during an alumina manufacturing process. This method enables the manufacture of glass articles with a high content of recycled raw materials and low quality deviation. The method further includes a method for manufacturing glass articles having a glass composition comprising SiO2, Al2O3, and Na2O. The glass raw material composition is melted, comprising at least 2% by mass of a first raw material particle and comprising multiple raw material particles with compositions different from the first raw material particle. The first raw material particle contains 20% to 70% by mass of SiO2, 20% to 75% by mass of Al2O3, and 0% to 10% by mass of Na2O.

Description

Technical Field

[0001] This invention relates to a method for manufacturing glass articles. Background Technology

[0002] Alumina is a type of ceramic widely used in various technical fields. One industrial method for manufacturing alumina is as follows: Bauxite is dissolved in an aqueous sodium hydroxide solution, causing red mud containing impurities such as iron to precipitate and be removed. The solution after removing the red mud is diluted with water, causing aluminum hydroxide to precipitate. A dealkalizing agent such as silica sand is added to the obtained aluminum hydroxide, and the mixture is calcined. The dealkalizing agent is then separated and removed from the calcined product, thus obtaining alumina (Al₂O₃).

[0003] For example, Patent Document 1 describes a method for manufacturing low-alkali alumina as follows: an alumina raw material containing sodium is mixed with a dealkali-removing agent comprising a silica-based substance and a ceramic-coated silica-based substance coated with a ceramic other than a silica-based substance; the resulting mixture is calcined; and then the dealkali-removing agent is separated. Furthermore, Patent Document 1 describes that after calcination, the mixture can be separated into alumina and the dealkali-removing agent using a dry classifier such as a sieve.

[0004] Furthermore, Patent Document 2 describes a method for manufacturing molten glass as follows: A glass raw material composition comprising silica sand, alumina, and an alkali metal source is melted to produce molten glass having a glass composition (oxide basis) with a SiO2 content of 50% by mass or more, an Al2O3 content of 5% by mass or more, and a total content of Li2O, Na2O, and K2O of 5% by mass or more. In Patent Document 2, the silica sand included in the glass raw material composition is described as having a D90 of 450 μm or more and 600 μm or less, and a difference between D90 and D10 of 350 μm or more. Additionally, Patent Document 2 describes alumina included in the glass raw material composition as having a D90 of 200 μm or less. Furthermore, Patent Document 2 describes the production of molten glass by melting a glass raw material composition and shards of glass with the same glass composition as the target molten glass, as needed. Shards of glass refer to glass fragments discharged during glass manufacturing processes, etc.

[0005] In recent years, from the perspectives of Sustainable Development Goals (SDGs) and environmental protection, the reuse of waste as resources is being promoted in various technological fields. In the glass industry, the use of recycled materials is also being explored.

[0006] As methods for reusing glass products, there are post-consumer recycling (PCR), which recycles products used in the market and utilizes them as resources, and post-industrial recycling (PIR), which recycles waste generated in the manufacturing process of products before they are put on the market and uses it as materials.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2003-12323

[0010] Patent Document 2: Patent No. 6981426 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, sheet glass products are typically assembled into electronic devices, buildings, automobiles, and other applications. Therefore, sheet glass products, in particular, are difficult to recycle and reuse after use in the market. Consequently, there is a need to utilize waste generated during the manufacturing process before products are placed on the market to increase the content of recyclable materials in the raw materials for sheet glass.

[0013] Furthermore, in the alumina (Al2O3) manufacturing process, the alkali removal agent separated from the calcination products containing alumina is treated as waste. In recent years, research has been conducted on reusing this waste alkali removal agent as a resource.

[0014] The present invention was made in view of the above circumstances, and its object is to provide a method for manufacturing glass articles, which uses a glass raw material composition containing a dealkalizing agent separated from the calcined product containing alumina in the alumina manufacturing process, and is able to manufacture glass articles with a high content of recycled raw materials and small quality deviations.

[0015] means for solving problems

[0016] In order to solve the above problems, and to manufacture glass products with high content of recycled raw materials and low quality deviation in the raw materials by using a glass raw material composition containing a dealkalizing agent separated from the calcination product containing alumina in the alumina manufacturing process, the inventors have conducted in-depth research.

[0017] The results showed that the large deviation in the quality of glass products manufactured using glass raw material compositions containing the aforementioned alkali removal agent was due to the large deviation in the composition of the alkali removal agent.

[0018] Therefore, the inventors focused on the composition of the alkali removal agent and the glass product, and conducted repeated studies. The results showed that a glass raw material composition containing more than 2% by mass of raw material particles with a specific composition can be melted to manufacture glass products with a specific composition.

[0019] Furthermore, by using this manufacturing method, glass products with a specific composition can be manufactured using a glass raw material composition containing the aforementioned dealkalizing agent as raw material particles. This allows for the increase of the content of recycled raw materials in the raw materials and the manufacture of glass products with small quality deviations, thus leading to the present invention.

[0020] [1] A method for manufacturing a glass article, which is a method for manufacturing a glass article having a glass composition comprising SiO2, Al2O3 and Na2O, wherein a glass raw material composition is melted, the glass raw material composition comprising more than 2% by mass of a first raw material particle and comprising a variety of raw material particles with different compositions from the first raw material particle, wherein the content of SiO2 in the first raw material particle is 20% to 70% by mass, the content of Al2O3 is 20% to 75% by mass, and the content of Na2O is 0% to 10% by mass.

[0021] [2] According to the glass article manufacturing method described in [1], the glass article manufacturing method manufactures a glass article having the following glass composition: based on oxides, the content of SiO2 in the glass composition is 45% by mass or more, the content of Al2O3 is 5% by mass or more, and the total content of Li2O, Na2O and K2O is 5% by mass or more.

[0022] [3] According to the glass product manufacturing method described in [1], the first raw material particle is a particle with a D70 less than or equal to that of the raw material precursor particle obtained by classifying the raw material precursor particle into particles with a D70 greater than that of the raw material precursor particle and particles with a D70 less than or equal to that of the raw material precursor particle.

[0023] [4] According to the glass product manufacturing method described in [1], the first raw material particle is a particle with a D60 less than or equal to that of the raw material precursor particle obtained by classifying the raw material precursor particle into particles with a D60 greater than that of the raw material precursor particle and particles with a D60 less than or equal to that of the raw material precursor particle.

[0024] [5] According to the glass product manufacturing method of [1], the first raw material particle is a particle with a D50 less than or equal to that of the raw material precursor particle obtained by classifying the raw material precursor particle into particles with a D50 greater than that of the raw material precursor particle and particles with a D50 less than or equal to that of the raw material precursor particle.

[0025] [6] In the method for manufacturing glass products according to [1], the particle size of the first raw material particles is less than 1400 μm.

[0026] [7] In the method for manufacturing glass products according to [1], the particle size of the first raw material particles is less than 1180 μm.

[0027] [8] In the method for manufacturing glass products according to [1], the particle size of the first raw material particles is less than 1000 μm.

[0028] [9] The method for manufacturing glass products as described in [1], wherein the particle size of the first raw material particles is less than 850 μm.

[0029]

[10] According to the method for manufacturing glass articles described in [1], wherein the glass raw material composition comprises a second raw material particle, the second raw material particle being silica sand with a D90 of less than 2000 μm.

[0030]

[11] In the glass manufacturing method according to

[10] , the second raw material particle is silica sand with a D90 of 100 μm or more.

[0031]

[12] According to the glass article manufacturing method of

[10] , the glass raw material composition includes a third raw material particle, the third raw material particle being the raw material particle with the largest D50 among the various raw material particles, and the composition of the third raw material particle is different from that of the first raw material particle and the second raw material particle. The first raw material particle is a particle with a D99 less than or equal to that of the third raw material particle, obtained by classifying raw material precursor particles into particles with a D99 greater than that of the third raw material particle and particles with a D99 less than or equal to that of the third raw material particle.

[0032]

[13] According to the method for manufacturing glass products described in [1], the first raw material particle has a core-shell structure, the core-shell structure having: a core with a SiO2 content of 90% by mass or more; and a shell formed in a manner covering the core and having an Al2O3 content of 90% by mass or more.

[0033]

[14] In the method for manufacturing glass articles according to

[13] , the larger the particle size of the first raw material particle, the smaller the ratio of the thickness of the shell portion to the particle size of the first raw material particle.

[0034]

[15] According to the glass manufacturing method described in [1], sodium aluminate obtained by dissolving bauxite in an aqueous sodium hydroxide solution is hydrolyzed, a calcined product containing Al2O3 is produced by calcining a mixture containing the obtained aluminum hydroxide and silica sand, raw material precursor particles are produced by separating Al2O3 from the calcined product, and the first raw material particles are obtained by classifying the raw material precursor particles to remove large particles from the raw material precursor particles.

[0035]

[16] According to the glass product manufacturing method of [1], the first raw material particle is a dealkalizing agent separated from a calcined product containing alumina in the alumina manufacturing process.

[0036]

[17] According to the method for manufacturing glass products described in [1], the first raw material particle has a core-shell structure with a shell of substantially uniform thickness.

[0037] Invention Effects

[0038] According to the glass article manufacturing method of the present invention, a glass raw material composition containing a dealkalizing agent separated from a calcination product containing alumina in the alumina manufacturing process can be used to manufacture glass articles with a high content of recycled raw materials and small quality deviations. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating an example of a method for manufacturing a glass article according to the first embodiment.

[0040] Figure 2 A photograph showing the analytical results of a precursor particle.

[0041] Figure 3 A photograph showing the analytical results of multiple raw material precursor particles.

[0042] Figure 4 A photograph showing the analytical results of multiple raw material precursor particles.

[0043] Label Explanation

[0044] S11 Raw material precursor particle manufacturing process, S12 Raw material precursor particle classification process, S2 Second raw material particle preparation process, S3 Third raw material particle preparation process, S4 Melting process, S5 Forming and solidification process. Detailed Implementation

[0045] The following definitions apply to this specification and the claims.

[0046] The glass composition is represented by oxides such as SiO2, Al2O3, and Na2O. The content of each component relative to the entire glass (glass composition) is expressed as a mass percentage based on the oxide basis.

[0047] The measurement methods of "particle size", "D70", "D60", "D50", "D90", and "D99" in the present invention are as described below.

[0048] <Method for measuring particle size>

[0049] The particle size of the first raw material particles and the particle size of the raw material precursor particles in the present invention refer to the values obtained by measuring the particle size of the first raw material particles or the raw material precursor particles by the method shown below.

[0050] The particle size is measured using a laser diffraction / scattering particle size distribution analyzer "Product name: LA-960" manufactured by HORIBA.

[0051] In addition, for the raw material precursor particles classified by a sieve, the range of the sieve pore size used in the classification is set as the range of the particle size.

[0052] <Method for measuring D70, D60, D50, D90, and D99>

[0053] "D70" is the 70% diameter in the cumulative fraction based on volume obtained by measuring the particle size using the laser diffraction method.

[0054] "D60" is the 60% diameter in the cumulative fraction based on volume obtained by measuring the particle size using the laser diffraction method.

[0055] "D50" is the 50% diameter in the cumulative fraction based on volume obtained by measuring the particle size using the laser diffraction method.

[0056] "D90" is the 90% diameter in the cumulative fraction based on volume obtained by measuring the particle size using the laser diffraction method.

[0057] "D99" is the 99% diameter in the cumulative fraction based on volume obtained by measuring the particle size using the laser diffraction method.

[0058] Hereinafter, a method for manufacturing a glass product according to an embodiment will be described with reference to the accompanying drawings. [[ID= 37]]

[0059] Figure 1 It is a flowchart for illustrating an example of a method for manufacturing a glass product according to the first embodiment. The method for manufacturing a glass product according to this embodiment is a method for manufacturing a glass product having the glass composition described below.

[0060] As Figure 1As shown, the glass article manufacturing method of this embodiment includes a melting step S4 in which the glass raw material composition is melted and a forming and solidification step S5.

[0061] Melting process S4

[0062] In the melting process S4, the glass raw material composition is melted to produce molten glass.

[0063] The glass raw material composition includes first raw material particles and also includes multiple raw material particles with compositions different from the first raw material particles. In this embodiment, the multiple raw material particles include second and third raw material particles.

[0064] Furthermore, the glass raw material composition preferably contains, within a range that does not impair the effects of the present invention, other known raw materials as glass raw materials besides the first, second, and third raw material particles, together with the first, second, and third raw material particles. Specifically, as other raw materials, it is preferable to contain one or more selected from alumina particles, alkali metal sources, alkaline earth metal sources, and boron sources.

[0065] Furthermore, the glass raw material composition may contain one or more of the following as other raw materials as needed, within the scope not impairing the effects of the present invention: tin oxide, titanium oxide, zircon oxide, zircon, cerium oxide, antimony oxide, iron oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, etc.

[0066] (First raw material particle)

[0067] The first raw material particles are the SiO2, Al2O3, and Na2O components contained in the glass raw material composition. The SiO2 content of the first raw material particles is 30% to 70% by mass, the Al2O3 content is 20% to 60% by mass, and the Na2O content is 0% to 10% by mass.

[0068] In the glass manufacturing method of this embodiment, since the contents of SiO2, Al2O3, and Na2O contained in the first raw material particles are within the aforementioned range, the first raw material particles can be directly used as a dealkali removal agent, a waste product separated from the calcination product containing alumina in the alumina manufacturing process. The aforementioned dealkali removal agent is a byproduct produced by the reaction accompanying the calcination used to generate alumina. It has a core-shell structure, comprising a core with a SiO2 content of 90% by mass or more and a shell formed to cover the core, containing an Al2O3 content of 85% by mass or more, and also containing Na2O.

[0069] In the glass article manufacturing method of this embodiment, in order to obtain the preferred first raw material particles, such as Figure 1As shown, it is preferable to perform the "raw material precursor particle manufacturing process S11" and the "raw material precursor particle classification process S12" before the melting process. Both the "raw material precursor particle manufacturing process S11" and the "raw material precursor particle classification process S12" can be performed as needed. For example, if the first raw material particle is directly used as a waste product generated in the alumina manufacturing process, i.e., the aforementioned dealkalizing agent, then the "raw material precursor particle manufacturing process S11" and the "raw material precursor particle classification process S12" may not be performed.

[0070] "Raw material precursor particle manufacturing process S11"

[0071] In the raw material precursor particle manufacturing process S11, raw material precursor particles, which serve as the first raw material particles, are manufactured. As the raw material precursor particles, a dealkalizing agent separated from the calcined product containing alumina manufactured in the alumina manufacturing process can be used. Therefore, the raw material precursor particle manufacturing process S11 can be a part of the alumina manufacturing process.

[0072] In the raw material precursor particle manufacturing process S11, bauxite is first dissolved in an aqueous sodium hydroxide solution to prepare an aqueous sodium aluminate solution. Next, the obtained sodium aluminate is hydrolyzed to produce aluminum hydroxide. Then, a calcined product containing Al2O3 is produced by calcining a mixture containing the obtained aluminum hydroxide and silica sand as a dealkalizing agent. Al2O3 is then separated from the obtained calcined product, thereby producing raw material precursor particles. The raw material precursor particles produced by this operation sometimes inevitably contain Na2O from the sodium component contained in the aqueous sodium hydroxide solution used in the alumina manufacturing process.

[0073] The mixture produced in the raw material precursor particle manufacturing process S11 is preferably a substance containing 70% to 95% by mass aluminum hydroxide and 5% to 30% by mass silica sand.

[0074] Furthermore, in the alumina manufacturing process, the calcination of the mixture produced in the raw material precursor particle manufacturing process S11 can be carried out using the same known method as the calcination of a mixture obtained by adding silica sand as a dealkalizing agent to aluminum hydroxide. Specifically, it can be carried out by heating at a temperature of 1000°C to 1400°C for 10 minutes to 10 hours.

[0075] Furthermore, as a method for separating Al2O3 from calcined products to obtain precursor particles, the same known methods as those used for separating dealkali-removing agents from calcined products containing alumina can be used in the alumina manufacturing process. Specifically, methods such as separation by classification using a dry classifier such as a screening machine can be employed.

[0076] "Raw material precursor particle classification process S12"

[0077] In the case where the raw material precursor particles obtained in the raw material precursor particle manufacturing process S11 are a dealkalizing agent separated from a calcined product containing alumina manufactured in the alumina manufacturing process, the raw material precursor particles have the aforementioned core-shell structure.

[0078] The difference in shell thickness caused by the difference in particle size among the core-shell structured particles forming the aforementioned dealkali-removing agent is small. More specifically, the shell thickness is approximately 200 μm, which is essentially constant regardless of the particle size of the core-shell structured particles. Therefore, the larger the particle size of the raw material precursor particles, the smaller the ratio of shell thickness to particle size. Thus, for both the raw material precursor particles and the first raw material particles obtained by classifying the raw material precursor particles, a larger particle size results in a higher SiO2 content and lower Al2O3 and Na2O content; a greater deviation in particle size leads to a greater deviation in composition.

[0079] In the raw material precursor particle classification process S12, the raw material precursor particles are classified to obtain first raw material particles from which large particles have been removed. The first raw material particles obtained through this operation do not contain large raw material precursor particles, and therefore have a lower SiO2 content and a higher ratio of Al2O3 to Na2O content compared to the raw material precursor particles. Therefore, by including the first raw material particles in the glass raw material composition, the ratio of Al2O3 content in the glass raw material composition to that in the first raw material particles can be increased. Thus, in the case where the raw material precursor particles are the aforementioned dealkalizing agent, which is considered waste, it is easy to further increase the content of recycled raw materials in the raw materials of the glass products. Furthermore, since the first raw material particles do not contain large raw material precursor particles, the compositional deviation is smaller, and the meltability is good, which is satisfactory.

[0080] Specifically, the first raw material particle is preferably a particle with a D70 less than or equal to that of the raw material precursor particles, obtained by classifying the raw material precursor particles into particles with a D70 greater than that of the raw material precursor particles and particles with a D70 less than or equal to that of the raw material precursor particles.

[0081] Furthermore, the first raw material particles are more preferably particles with a D60 less than or equal to that of the raw material precursor particles, obtained by classifying the raw material precursor particles into particles with a D60 greater than that of the raw material precursor particles and particles with a D60 less than or equal to that of the raw material precursor particles. Compared with the case where the first raw material particles are particles with a D70 less than or equal to that of the raw material precursor particles, the first raw material particles obtained by this operation have a lower SiO2 content, a higher Al2O3 content, higher compositional uniformity, and better melting properties.

[0082] Furthermore, the first raw material particles are more preferably particles with a D50 less than or equal to that of the raw material precursor particles, obtained by classifying the raw material precursor particles into particles with a D50 greater than that of the raw material precursor particles and particles with a D50 less than or equal to that of the raw material precursor particles. Compared with the case where the first raw material particles are particles with a D60 less than or equal to that of the raw material precursor particles, the first raw material particles obtained by this operation have a lower SiO2 content, a higher Al2O3 content, higher compositional uniformity, and better melting properties.

[0083] Furthermore, in the raw material precursor particle classification process S12, it is preferable to manufacture first raw material particles with a particle size of 1400 μm or less by classifying the raw material precursor particles. When the particle size of the first raw material particles is 1400 μm or less, it does not contain raw material precursor particles with large particle sizes, so the content of SiO2 is low, the content of Al2O3 is high, the compositional deviation is small, and the melting properties are good.

[0084] In the raw material precursor particle classification process S12, it is preferable to obtain first raw material particles with a particle size of 1400 μm or less by classifying the raw material precursor particles; more preferably, first raw material particles with a particle size of 1180 μm or less; even more preferably, first raw material particles with a particle size of 1000 μm or less; and particularly preferably, first raw material particles with a particle size of 850 μm or less. The reason for this is that, when the raw material precursor particles are the aforementioned dealkalizing agent, which is a waste product, the content of SiO2 is low, the content of Al2O3 is high, the composition is highly uniform, and the melting properties are good.

[0085] Furthermore, the first raw material particles are more preferably obtained by classifying the raw material precursor particles into particles larger than 1400 μm and particles smaller than or equal to 1400 μm. The first raw material particles obtained by this operation contain 20% to 70% by mass of SiO2, 20% to 75% by mass of Al2O3, and 0% to 10% by mass of Na2O, resulting in higher compositional uniformity and better melting properties.

[0086] Furthermore, the first raw material particles are more preferably obtained by classifying raw material precursor particles into particles larger than 1180 μm and particles smaller than or equal to 1180 μm. The first raw material particles obtained by this operation contain 20% to 60% by mass of SiO2, 30% to 75% by mass of Al2O3, and 1% to 7% by mass of Na2O, resulting in higher compositional uniformity and better melting properties.

[0087] Furthermore, the first raw material particles are more preferably obtained by classifying raw material precursor particles into particles larger than 1000 μm and particles smaller than or equal to 1000 μm. The first raw material particles obtained by this operation contain 20% to 50% by mass of SiO2, 35% to 75% by mass of Al2O3, and 2% to 7% by mass of Na2O, and exhibit good melting properties.

[0088] Furthermore, the first raw material particles are more preferably obtained by classifying raw material precursor particles into particles larger than 850 μm and particles smaller than or equal to 850 μm. The first raw material particles obtained by this operation contain 20% to 50% by mass of SiO2, 40% to 75% by mass of Al2O3, and 3% to 7% by mass of Na2O, resulting in higher compositional uniformity and better melting properties.

[0089] In the raw material precursor particle classification process S12, the methods for classifying the raw material precursor particles can include, for example, well-known methods such as using a filter, such as a sieve, using gravity based on the difference in falling speed or falling position of the particles, using centrifugal force, such as a cyclone, and using inertial force.

[0090] When the raw material precursor particles are a dealkali-removing agent separated from a calcined product containing alumina manufactured in the alumina manufacturing process, the first raw material particles obtained in the raw material precursor particle classification process S12 have a core-shell structure. This core-shell structure has a core with a SiO2 content of 90% by mass or more and a shell with an Al2O3 content of 90% by mass or more formed to cover the core, and also contains Na2O. The larger the particle size of the first raw material particle, the smaller the ratio of the shell thickness to the particle size of the first raw material particle. In addition, when the raw material precursor particles are the aforementioned dealkali-removing agent, the first raw material particles sometimes have a core-shell structure with a substantially uniform shell thickness.

[0091] (Second raw material particles)

[0092] In the glass product manufacturing method of this embodiment, a second raw material particle is prepared before the melting process (second raw material particle preparation process S2).

[0093] The second raw material particle is SiO2 contained in the glass raw material composition. In the glass product manufacturing method of this embodiment, commercially available silica sand can be used directly as the second raw material particle.

[0094] The particle size range of the second raw material particles is preferably similar to that of the first raw material particles. This is because it will result in a glass raw material composition with good melting properties.

[0095] The D90 of the second raw material particles is preferably 100 μm or more. When the D90 of the second raw material particles is 100 μm or more, the deviation between the particle size of the second raw material particles and the particle size of the first raw material particles is easily reduced. As a result, the meltability of the glass raw material composition becomes better in the melting process S4, and glass products with even smaller quality deviations can be manufactured. The D90 of the second raw material particles is more preferably 300 μm or more, more preferably 450 μm or more, and particularly preferably 600 μm or more.

[0096] Furthermore, the D90 of the second raw material particles is preferably 2000 μm or less. When the D90 of the second raw material particles is 2000 μm or less, the meltability when melting the glass raw material composition is more easily improved. The D90 of the second raw material particles is more preferably 1400 μm or less, further preferably 1180 μm or less, more preferably 1000 μm or less, and particularly preferably 800 μm or less.

[0097] (Third raw material particles)

[0098] In the glass product manufacturing method of this embodiment, a third raw material particle is prepared before the melting process (third raw material particle preparation process S3).

[0099] The third raw material particle is the raw material particle with the largest D50 among the various raw material particles contained in the glass raw material composition. The composition of the third raw material particle differs from that of the first and second raw material particles. Examples of third raw material particles include particles containing potassium carbonate and sodium carbonate. The third raw material particle can be, for example, a coarse particle with a D50 of 350 μm to 550 μm and a D90 of 550 μm to 850 μm.

[0100] As described above, the third raw material particle is the coarse particle with the largest D50 among the various raw material particles contained in the glass raw material composition. In this embodiment, it is preferable to classify the raw material precursor particles that become the first raw material particles based on the D99 value of the coarse particles, i.e., the third raw material particles.

[0101] Specifically, the first raw material particle is preferably a particle with a D99 value less than or equal to that of the third raw material particle, obtained by classifying the raw material precursor particles into particles with a D99 value greater than or equal to that of the third raw material particle. The reason for this is that, since there are no large-sized first raw material particles, glass products with smaller quality deviations can be manufactured. More preferably, the first raw material particle is a particle with a D90 value less than or equal to that of the third raw material particle, obtained by classifying the raw material precursor particles into particles with a D90 value greater than or equal to that of the third raw material particle.

[0102] (alumina particles)

[0103] As alumina (Al2O3) particles, particles with a D90 of 150 μm or less are preferred, particles with a D90 of 100 μm or less are more preferred, particles with a D90 of 90 μm or less are even more preferred, and particles with a D90 of 85 μm or less are particularly preferred.

[0104] When the content of Al2O3 in the glass raw material composition is within the range of the target glass composition due to the Al2O3 contained in the first raw material particles, the glass raw material composition may not contain alumina particles.

[0105] (Alkali metal source)

[0106] Alkali metal sources are compounds formed by melting to form Na₂O, K₂O, or Li₂O. There are no particular limitations on the particle size of the alkali metal source, and known alkali metal sources can be used. Examples of alkali metal sources include: carbonates, sulfates, nitrates, oxides, hydroxides, chlorides, and fluorides of alkali metals. In this invention, alkali metals refer to Na, K, and Li. Only one alkali metal source can be used, or two or more can be used in combination. Examples of alkali metal carbonates are preferably sodium carbonate, potassium carbonate, and lithium carbonate, especially sodium carbonate (soda ash), which is suitable from the viewpoint of ease of handling.

[0107] When the Na2O content in the glass raw material composition is within the range of the target glass composition due to the Na2O contained in the first raw material particles, the glass raw material composition may not contain an alkali metal source.

[0108] (Alkali earth metal source)

[0109] Alkaline earth metal sources are compounds formed by melting MgO, CaO, BaO, and SrO, which may be included as needed. Examples of alkaline earth metal sources include carbonates, sulfates, nitrates, oxides, hydroxides, chlorides, and fluorides of alkaline earth metals. In this specification, alkaline earth metals refer to Mg, Ca, Ba, and Sr. Only one alkaline earth metal source may be used, or two or more may be used in combination. There are no particular restrictions on the particle size of the alkaline earth metal source; well-known alkaline earth metal sources can be used. Additionally, composite carbonates such as dolomite and composite oxides such as calcined dolomite may also be used.

[0110] (Boron source)

[0111] Examples of boron sources include boric acid, boron oxide (B₂O₃), and borate. A single boron source can be used, or two or more can be used in combination. Examples of boric acids include orthoboric acid (H₃BO₃), metaboric acid (HBO₂), and tetraboric acid (H₂B₄O₇).

[0112] (Composition of the glass raw material composition)

[0113] The glass raw material composition preferably has a glass composition having, based on oxides, a SiO2 content of 45% or more by mass, an Al2O3 content of 5% or more by mass, and a total content of Li2O, Na2O, and K2O of 5% or more by mass.

[0114] The glass raw material composition is prepared by mixing the aforementioned first raw material particles, second raw material particles, third raw material particles, and other raw materials as needed, in a manner that achieves the target glass composition. Except for components that are easily volatile during melting, the glass composition of the glass raw material composition, converted from oxides, is adjusted to be approximately the same as the glass composition of the target glass article. In the glass raw material composition, clarifying agents and oxides with clarifying effects may be mixed as easily volatile components.

[0115] In this embodiment, the content of the first raw material particles contained in the glass raw material composition is 2% by mass or more. Therefore, when the first raw material particles are the aforementioned dealkalizing agent, which is waste, glass articles with a sufficiently high content of recycled raw materials can be obtained. The content of the first raw material particles contained in the glass raw material composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. This is because it allows for a higher content of recycled raw materials in the glass articles. In addition, the content of the first raw material particles contained in the glass raw material composition is preferably 35% by mass or less, more preferably 25% by mass or less. The reason for this is that glass articles with even smaller quality deviations can be obtained.

[0116] In this embodiment, the preferred glass and microcrystalline glass composition (total 100% by mass) as the glass raw material composition can be, for example, the following compositions (1) to (5).

[0117] Composition (1): SiO2 is 45% to 75% by mass, Al2O3 is 5% to 30% by mass, B2O3 is 0% to 20% by mass, Li2O, Na2O and K2O are 5% to 35% by mass, and MgO, CaO, SrO and BaO are 0% to 20% by mass.

[0118] Composition (2): SiO2 is 45% to 75% by mass, Al2O3 is 7% to 30% by mass, B2O3 is 0% to 20% by mass, Li2O, Na2O and K2O are 5% to 35% by mass, and MgO, CaO, SrO and BaO are 0% to 20% by mass.

[0119] Composition (3): SiO2 is 45% to 75% by mass, Al2O3 is 7% to 30% by mass, B2O3 is 0% to 20% by mass, and does not actually contain Li2O. The total of Na2O and K2O is 5% to 35% by mass, and the total of MgO, CaO, SrO and BaO is 0% to 20% by mass.

[0120] Composition (4): SiO2 is 45% to 75% by mass, Al2O3 is 7% to 30% by mass, B2O3 is 0% to 20% by mass, Li2O is 1% to 20% by mass, the total of Li2O, Na2O and K2O is 5% to 35% by mass, and the total of MgO, CaO, SrO and BaO is 0% to 20% by mass.

[0121] Composition (5): SiO2 is 45% to 75% by mass, Al2O3 is 7% to 30% by mass, B2O3 is 0% to 20% by mass, Li2O is 1% to 20% by mass, the total of Li2O, Na2O and K2O is 5% to 35% by mass, and the total of MgO, CaO, SrO and BaO is 0% to 20% by mass, and the content of Co3O4 or NiO, TiO2, Cr2O3, MnO2 and MoO3 is 0.0001% to 5% by mass.

[0122] (Melting method)

[0123] As a method for producing molten glass by melting a glass raw material composition, known methods can be used. Preferably, a method is used where the glass raw material composition is fed into a melting furnace for melting.

[0124] There are no particular limitations on the melting furnace for the molten glass raw material composition; it can be either intermittent or continuous. For example, the glass raw material composition and shards of glass, which are identical to the desired glass product, are continuously fed into the melting furnace and heated to approximately 1400°C to approximately 1700°C to melt them, thereby producing molten glass. It should be noted that shards of glass refer to glass fragments discharged during the glass manufacturing process, etc.

[0125] “Forming and Solidification Process S5”

[0126] In the forming and solidification process S5, the molten glass generated in the melting process S4 is formed into a predetermined shape and then slowly cooled and solidified as needed. In the forming and solidification process S5 of this embodiment, known methods such as float glass, drop glass, and fusion glass can be used as methods for forming the molten glass into the predetermined shape. Furthermore, the molten glass generated in the melting process S4 can be formed using methods such as compression molding or blow molding. Additionally, as a method for forming the molten glass, a fiber-based forming method can also be used.

[0127] Then, post-processing is performed using known methods such as cutting and grinding, as needed. This yields the glass product of this embodiment.

[0128] The glass product manufacturing method of this embodiment is a method for manufacturing glass products having a specified glass composition, wherein a glass raw material composition is melted, the glass raw material composition containing at least 2% by mass of a first raw material particle and including a variety of raw material particles different from the first raw material particle, wherein the first raw material particle contains 20% to 70% by mass of SiO2, 20% to 75% by mass of Al2O3, and 0% to 10% by mass of Na2O. Therefore, by using a dealkalizing agent separated from calcined products containing alumina in the alumina manufacturing process, or particles obtained by classifying the dealkalizing agent, as the first raw material particle, the content of recycled raw materials in the raw materials of the glass product can be increased, and glass products with small quality deviations can be manufactured.

[0129] The glass product manufacturing method of this embodiment is a method for manufacturing glass products using a glass raw material composition containing a dealkalizing agent as a recycled raw material. In this embodiment, the objective is to provide a method for manufacturing glass products that can produce glass products with a sufficiently high content of recycled raw materials in the raw material and small quality deviations. Glass products manufactured using the method of this embodiment using recycled raw materials can be, for example, sheet glass. Glass products manufactured using the method of this embodiment are not limited to sheet glass; for example, they can also be bottle-shaped glass, glass blocks, glass beads, etc. Furthermore, the glass obtained by melting in the manufacturing method of this embodiment can also be heat-treated to become microcrystalline glass or phase-separated glass.

[0130] Example

[0131] The present invention will now be described in more detail using examples. However, the present invention is not limited to these examples.

[0132] (Precursor particles)

[0133] As precursor particles, a dealkali removal agent (C1) separated from calcined products containing alumina produced in the alumina manufacturing process was prepared. The precursor particles were analyzed for shape and elemental composition using an electron probe microanalyzer (EPMA) (trade name: JXA-8230; manufactured by JEOL Corporation) under the conditions shown below. The results are presented below. Figures 2-4 middle.

[0134] Precursor particles were embedded in resin and ground until they appeared on the surface, thus preparing the sample. Approximately 30 nm of platinum was then sputtered onto the surface of the obtained sample, followed by EPMA analysis. In EPMA, the accelerating voltage was 15 kV, the probe current was 50 nA, and the probe diameter was 1 μm. Under the conditions of a step size interval of 10 μm and a measurement time of 10 ms, the mapping of characteristic X-ray counts for SiO2, Al2O3, and Na2O were obtained, respectively.

[0135] Figure 2 It is a photograph showing the analytical results of a precursor particle. Figure 3 and Figure 4 These are photographs showing the analytical results of various raw material precursor particles. Figure 2 (a) Figure 3 (a) Figure 4 (a) is a photograph of a reflected electron image. Figure 2 (b) Figure 3 (b) Figure 4(b) is a photograph showing the results of the surface analysis (mapping analysis) of SiO2. Figure 2 (c) Figure 3 (c) Figure 4 (c) is a photograph showing the results of surface analysis (mapping analysis) of Al2O3. Figure 2 (d) Figure 3 (d) Figure 4 (d) is a photograph showing the surface analysis (mapping analysis) results of Na2O.

[0136] like Figures 2-4 As shown, it was confirmed that the precursor particles used as a dealkali removal agent separated from the calcined product containing alumina manufactured in the alumina production process have a core-shell structure. This core-shell structure has a core with a SiO2 content of 90% by mass or more and a shell formed to cover the core with an Al2O3 content of 85% by mass or more. Furthermore, in Figures 2-4 In the raw material precursor particles shown, the difference in the thickness of the shell portion of the core-shell structure caused by the difference in particle size is small, and the thickness of the shell portion is basically constant.

[0137] In addition, by Figures 2-4 The surface analysis (mapping analysis) results of the precursor particles shown confirmed that the precursor particles possess a core-shell structure with a large number of shells containing Al2O3. Therefore, using the surface analysis results of Al from EPMA-based scanning electron microscopy (SEM) images, the thickness of the regions where Al was detected was determined by the method shown below, and this thickness was taken as the shell thickness. The results are as follows: Figures 2-4 The shell thickness of the raw material precursor particles shown is approximately 200 μm.

[0138] <Determination of Shell Thickness>

[0139] The SEM images were magnified to 200–400x to include various precursor particles within a single field of view. From the obtained SEM images, five particles with annular regions containing Al were selected, observed along their outer periphery. Then, for each particle's annular region containing Al, the thickness was measured at four equally spaced points along the outer periphery in the direction from the periphery towards the center. The average thickness was calculated and taken as the thickness of the Al region. The average thickness of the Al region of the five precursor particles obtained through this process was calculated and taken as the shell thickness.

[0140] (First raw material particle)

[0141] As raw material precursor particles, dealkalizing agents of different batches (Al) to (Cl) were prepared, which were separated from calcined products containing alumina and manufactured in the alumina manufacturing process.

[0142] Regarding the dealkalizing agents (A1) to (C1), the contents of SiO2, Al2O3, and Na2O were measured by the methods shown below. The results are shown in Table 1.

[0143] <Determination of the Contents of SiO2, Al2O3, and Na2O>

[0144] Regarding the composition of the dealkalizing agents, evaluation was carried out by XRF (X-ray Fluorescence Spectrometer) method. The analysis conditions of the XRF method are as described below. As the XRF measuring device, ZSX PrimusII manufactured by Rigaku Corporation was used. Based on the peaks of the obtained fluorescent X-rays, the contents of each component were calculated using the fundamental parameter method (Fundamental Parameter method).

[0145] (Analysis Conditions)

[0146] Output: Rh 50kV - 72mA

[0147] Filter: OUT Ni 400

[0148] Attenuator: 1 / 1

[0149] Slit: Std.

[0150] Spectrometer crystal: RX25 LiF(200)

[0151] Detector: PC

[0152] PHA: 110 - 450

[0153] Table 1

[0154] The error shown in Table 1 was calculated by preparing 5 samples for each dealkalizing agent and calculating the standard deviation of their measurement results.

[0155] As shown in Table 1, for the dealkalizing agents (A1) to (C1), the content of SiO2 is within the range of 20% to 70% by mass, the content of Al2O3 is within the range of 20% to 75% by mass, and the content of Na2O is within the range of 0% to 10% by mass.

[0156] Next, the dealkalizing agent (A1) was classified by the method shown below. For the dealkalizing agent (A1) in each particle size range after classification, the contents of SiO2, Al2O3, and Na2O were measured in the same manner as the dealkalizing agent (A1) before classification. The results are shown in Table 2.

[0157] <Grading Method 1>

[0158] Sieves with aperture sizes of 1400 μm, 1180 μm, 1000 μm, 850 μm, and 710 μm were prepared. The sieves were stacked from bottom to top in ascending order of aperture size. The pre-classified alkali-removing agent was placed on a 1400 μm sieve, and the sieve was vibrated. This process classified the pre-classified alkali-removing agent into particles with diameters ranging from 1400 μm and above, 1180 μm and above to less than 1400 μm, 1000 μm and above to less than 1180 μm, 850 μm and above to less than 1000 μm, 710 μm and above to less than 850 μm, and less than 710 μm.

[0159] Table 2

[0160] <Grading Method 2>

[0161] Sieves with aperture sizes of 1400 μm, 1180 μm, 1000 μm, and 850 μm were prepared. The pre-classified alkali-removing agent was placed on each sieve, and the sieves were vibrated. This process separated the pre-classified alkali-removing agent into particles with diameters less than 1400 μm, less than 1180 μm, less than 1000 μm, and less than 850 μm.

[0162] Table 3

[0163] The errors shown in Tables 2 and 3 were calculated by preparing five samples for each dealkali agent with different particle sizes and calculating the standard deviation of their measurement results.

[0164] As shown in Tables 2 and 3, it was confirmed that the contents of SiO2, Al2O3, and Na2O in the dealkali removal agent (A1) vary depending on its particle size. More specifically, it can be seen that the dealkali removal agent (A1) tends to have the following characteristics: the smaller the particle size, the lower the SiO2 content and the higher the contents of Al2O3 and Na2O.

[0165] Therefore, it can be seen that by limiting the particle size of the (A1) alkali-removing agent to a specific range, the deviation in its composition is reduced. Thus, it can be seen that the (A1) alkali-removing agent, by removing large particles through top cutting, narrows the range of particle size deviation and reduces compositional deviation.

[0166] (Second raw material particles)

[0167] Silica sand A and silica sand B were prepared as the second raw material particles. The particle size was measured using the same method as that used to determine the particle size of the first raw material particles, and D50 and D90 were calculated. The results are shown below.

[0168] Silica sand A: D90=946μm, D50=559μm

[0169] Silica sand C: D90=470μm, D50=262μm

[0170] (Third raw material particles)

[0171] For potassium carbonate and sodium carbonate particles, which are raw material particles with compositions different from the first and second raw material particles, their particle sizes were determined using the same method as the determination of the particle size of the first raw material particles described above. The results are shown in Table 4.

[0172] Table 4

Claims

1. A method for manufacturing a glass article, comprising manufacturing a glass article having a glass composition including SiO2, Al2O3, and Na2O, wherein, The glass raw material composition is melted. The glass raw material composition comprises more than 2% by mass of a first raw material particle and includes multiple raw material particles with compositions different from the first raw material particle. The first raw material particles contain 20% to 70% by mass of SiO2, 20% to 75% by mass of Al2O3, and 0% to 10% by mass of Na2O.

2. The method of making a glass article according to claim 1, wherein, The method for manufacturing glass articles produces glass articles having the following glass composition: Based on oxides, the composition of glass... The SiO2 content is 45% by mass or more. The Al2O3 content is 5% by mass or more. The combined content of Li2O, Na2O, and K2O is 5% by mass or more.

3. The method of manufacturing a glass article according to claim 1, wherein, The first raw material particle is a particle with a D70 less than or equal to that of the raw material precursor particles, obtained by classifying the raw material precursor particles into particles with a D70 greater than that of the raw material precursor particles and particles with a D70 less than or equal to that of the raw material precursor particles.

4. The method of manufacturing a glass article according to claim 1, wherein, The first raw material particle is obtained by classifying raw material precursor particles into particles with a D60 greater than that of the raw material precursor particles and particles with a D60 less than or equal to that of the raw material precursor particles.

5. The method of manufacturing a glass article according to claim 1, wherein, The first raw material particle is a particle with a D50 less than or equal to that of the raw material precursor particles, obtained by classifying the raw material precursor particles into particles with a D50 greater than that of the raw material precursor particles and particles with a D50 less than or equal to that of the raw material precursor particles.

6. The method of manufacturing a glass article according to claim 1, wherein, The particle size of the first raw material particles is less than 1400 μm.

7. The method of manufacturing a glass article according to claim 1, wherein, The particle size of the first raw material particles is below 1180 μm.

8. The method of manufacturing a glass article according to claim 1, wherein, The particle size of the first raw material particles is less than 1000 μm.

9. The method of manufacturing a glass article according to claim 1, wherein, The particle size of the first raw material particles is below 850 μm.

10. The method of making a glass article according to claim 1, wherein, The glass raw material composition includes a second raw material particle, which is silica sand with a D90 of less than 2000 μm.

11. The method of making a glass article according to claim 10, wherein, The second raw material particles are silica sand with a D90 of 100μm or more.

12. The method for manufacturing a glass article according to claim 10, wherein, The glass raw material composition includes a third raw material particle, which is the raw material particle with the largest D50 among the various raw material particles, and the composition of the third raw material particle is different from that of the first raw material particle and the second raw material particle. The first raw material particle is obtained by classifying the raw material precursor particles into particles with a D99 greater than that of the third raw material particle and particles with a D99 less than or equal to that of the third raw material particle.

13. The method for manufacturing a glass article according to claim 1, wherein, The first raw material particle has a core-shell structure, and the core-shell structure has: The core contains more than 90% by mass of SiO2; and A shell formed in a manner that covers the core, and having an Al2O3 content of 90% by mass or more.

14. The method for manufacturing a glass article according to claim 13, wherein, The larger the particle size of the first raw material particle, the smaller the ratio of the thickness of the shell to the particle size of the first raw material particle.

15. The method for manufacturing a glass article according to claim 1, wherein, Sodium aluminate obtained by dissolving bauxite in an aqueous sodium hydroxide solution is hydrolyzed, and a calcined product containing Al2O3 is produced by calcining a mixture containing the obtained aluminum hydroxide and silica sand. Raw material precursor particles are produced by separating Al2O3 from the calcined product, and the first raw material particles are obtained by classifying the raw material precursor particles to remove large particles from the raw material precursor particles.

16. The method for manufacturing a glass article according to claim 1, wherein, The first raw material particle is a dealkalizing agent separated from calcined products containing alumina during the alumina manufacturing process.

17. The method for manufacturing a glass article according to claim 1, wherein, The first raw material particle has a core-shell structure with a shell of approximately uniform thickness.

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