Manufacturing methods for glass products

Abstract

To provide a method for manufacturing glass products that uses a glass raw material composition containing a soda-removing agent separated from calcined products containing alumina in the alumina manufacturing process, thereby enabling the production of glass products with a high recycled material content and low variation in quality. [Solution] A method for producing a glass product having a glass composition containing SiO2, Al2O3, and Na2O, comprising dissolving a glass raw material composition containing 2% by mass or more of first raw material particles having an SiO2 content of 20% to 70% by mass, an Al2O3 content of 20% to 75% by mass, and a Na2O content of 0% to 10% by mass, and a plurality of raw material particles having different components from the first raw material particles.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing glass products.

Background Art

[0002] Alumina is one of the ceramics and is widely used in various technical fields. As one of the industrial production methods of alumina, there is the following method. Dissolve bauxite in an aqueous sodium hydroxide solution, precipitate and remove red mud composed of impurities such as iron. Dilute the solution from which the red mud has been removed with water to precipitate aluminum hydroxide. Add a desoda agent such as silica sand to the obtained aluminum hydroxide and bake it. Then, there is a method of obtaining alumina (Al2O3) by separating and removing the desoda agent from the baked product.

[0003] For example, Patent Document 1 describes a method for producing low-soda alumina in which an alumina raw material containing soda is mixed with a desoda agent composed of a ceramic-coated silica-based substance coated with a silica-based substance and a ceramic other than the silica-based substance, and after firing the obtained mixture, the desoda agent is separated. Further, Patent Document 1 describes that after firing, the mixture can be separated into alumina and a desoda agent using a dry classifier such as a sieve.

[0004] Furthermore, Patent Document 2 describes a method for producing molten glass by melting a glass raw material composition containing silica sand, aluminum oxide, and an alkali metal source to produce molten glass having a glass composition (oxide basis) in which the SiO2 content is 50% by mass or more, the Al2O3 content is 5% by mass or more, and the total content of Li2O, Na2O, and K2O is 5% by mass or more. Patent Document 2 describes silica sand contained in the glass raw material composition 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. Patent Document 2 also describes aluminum oxide contained in the glass raw material composition having a D90 of 200 μm or less. Furthermore, Patent Document 2 describes melting the glass raw material composition and, if necessary, cullet having the same glass composition as the target molten glass to produce molten glass. Cullet is glass waste discharged during the glass manufacturing process.

[0005] In recent years, recycling, which reuses waste as a resource, has been promoted in various technological fields from the perspective of the Sustainable Development Goals (SDGs) and environmental protection. In glass products, the use of recycled materials as raw materials is also being considered. There are two main methods for recycling glass products: post-consumer recycling (PCR), which involves collecting used products from the market and using them as resources, and post-industrial recycling (PIR), which involves collecting waste generated during the manufacturing process of products before they reach the market and using it as a material. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2003-12323 [Patent Document 2] Patent No. 6981426 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, flat glass products are typically used in electronic devices, buildings, automobiles, and other applications. Therefore, flat glass products are particularly difficult to recover individually after market use, making post-consumer recycling challenging. For this reason, there is a need to increase the recycled material content in the raw materials of flat glass by utilizing waste generated during the manufacturing process before the product reaches the market.

[0008] Furthermore, in the manufacturing process of alumina (Al2O3), the desodium ionizer separated from the calcined product containing alumina is treated as waste. In recent years, there has been consideration to reusing this waste desodium ionizer as a resource.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a method for manufacturing glass products that can produce glass products with a high content of recycled materials in the raw materials and with less variation in quality, by using a glass raw material composition containing a soda-removing agent separated from a calcined product containing alumina in the alumina manufacturing process. [Means for solving the problem]

[0010] The inventors have diligently studied how to solve the above problems and produce glass products with a high recycled material content and low variation in quality using a glass raw material composition containing a soda-removing agent separated from calcined products containing alumina in the alumina manufacturing process. As a result, it was found that the reason why glass products manufactured using the above-mentioned glass raw material composition containing the desodium sulfate agent exhibited large variations in quality was due to large variations in the composition of the desodium sulfate agent.

[0011] Therefore, the inventors focused on the composition of the soda-removing agent and the glass product and conducted extensive research. As a result, they discovered that a glass raw material composition containing 2% by mass or more of raw material particles having a specific composition can be dissolved to produce a glass product having a specific composition. Furthermore, by using this manufacturing method and a glass raw material composition containing the above-mentioned desoda-removing agent as raw material particles to produce glass products having a specific composition, it was confirmed that the recycled material content in the raw material could be increased, and glass products with less variation in quality could be produced, leading to the invention of this invention.

[0012] [1] A method for producing a glass product having a glass composition containing SiO2, Al2O3, and Na2O, The SiO2 content is 20% by mass to 70% by mass. Al2O3 content is 20% to 75% by mass. A method for producing glass products, comprising dissolving a glass raw material composition containing 2% by mass or more of first raw material particles having a Na2O content of 0% to 10% by mass, and also containing a plurality of raw material particles having different components from the first raw material particles.

[0013] [2] Based on oxides, the SiO2 content is 45% by mass or more. Al2O3 content of 5% by mass or more, A method for producing a glass product according to [1], wherein the glass product has a glass composition in which the total content of Li2O, Na2O, and K2O is 5% by mass or more.

[0014] [3] The method for manufacturing a glass product according to [1], wherein the first raw material particles are obtained by classifying the raw material precursor particles into particles with a D70 or higher and particles with a D70 or lower, and the first raw material precursor particles are particles with a D70 or lower. [4] The method for manufacturing a glass product according to [1], wherein the first raw material particles are obtained by classifying the raw material precursor particles into particles with a D60 or higher and particles with a D60 or lower, and the first raw material precursor particles are particles with a D60 or lower. [5] The method for manufacturing a glass product according to [1], wherein the first raw material particles are obtained by classifying the raw material precursor particles into particles with a D50 greater than the raw material precursor particles and particles with a D50 or less the raw material precursor particles.

[0015] [6] The method for manufacturing a glass product according to [1], wherein the particle diameter of the first raw material particles is 1400 μm or less. [7] The method for manufacturing a glass product according to [1], wherein the particle diameter of the first raw material particles is 1180 μm or less. [8] The method for manufacturing a glass product according to [1], wherein the particle diameter of the first raw material particles is 1000 μm or less. [9] The method for manufacturing a glass product according to [1], wherein the particle diameter of the first raw material particles is 850 μm or less.

[0016]

[10] The glass raw material composition contains second raw material particles, The method for manufacturing a glass product according to [1], wherein the second raw material particles are silica sand with a D90 of 2000 μm or less.

[11] The method for manufacturing a glass product according to

[10] , wherein the second raw material particles are silica sand with a D90 of 100 μm or more.

[0017]

[12] The glass raw material composition is the raw material particle with the largest D50 among the plurality of raw material particles, and includes third raw material particles having different components from the first raw material particles and the second raw material particles, The method for manufacturing a glass product according to

[10] , wherein the first raw material particles are particles of the third raw material particles with a D99 or less obtained by classifying raw material precursor particles into particles with a size exceeding D99 of the third raw material particles and particles with a size of D99 or less of the third raw material particles.

[0018]

[13] The first raw material particles have a core-shell structure having a core part with a SiO2 content of 90% by mass or more, and a shell part formed to cover the core part and having an Al2O3 content of 90% by mass or more. The method for manufacturing a glass product according to [1].

[14] The method for manufacturing a glass product according to

[13] , wherein the ratio of the thickness of the shell part to the particle diameter of the first raw material particles is smaller as the particle diameter of the first raw material particles is larger.

[0019]

[15] Dissolve bauxite in an aqueous sodium hydroxide solution, hydrolyze sodium aluminate obtained thereby, and fire a mixture containing the obtained aluminum hydroxide and silica sand to produce a fired product containing Al2O3. Separate Al2O3 from the fired product to produce raw material precursor particles, and classify the raw material precursor particles to obtain the first raw material particles from which particles having a large particle diameter have been removed from the raw material precursor particles. The method for producing a glass product according to [1].

[0020]

[16] The method for producing a glass product according to [1], wherein the first raw material particles are a desodizing agent separated from a fired product containing alumina in the alumina production process.

[17] The method for producing a glass product according to [1], wherein the first raw material particles have a core-shell structure with a substantially uniform shell thickness. [Advantages of the Invention]

[0021] According to the method for producing a glass product of the present invention, using a glass raw material composition containing a desodizing agent separated from a fired product containing alumina in the alumina production process, a glass product with a high content of recycled raw materials contained in the raw materials and little variation in quality can be produced. [Brief Description of the Drawings]

[0022] [Figure 1] FIG. 1 is a flowchart for explaining an example of the method for producing a glass product according to the first embodiment. [Figure 2] FIG. 2 is a photograph showing the analysis results of one raw material precursor particle. [Figure 3] FIG. 3 is a photograph showing the analysis results of a plurality of raw material precursor particles. [Figure 4] FIG. 4 is a photograph showing the analysis results of a plurality of raw material precursor particles. [Embodiments for Carrying Out the Invention]

[0023] The following definitions of terms apply throughout this specification and the claims. The glass composition is represented by oxides such as SiO2, Al2O3, and Na2O. The content of each component with respect to the entire glass (glass composition) is expressed as a mass percentage based on oxides. The measurement methods of "particle size", "D70", "D60", "D"50", "D90", and "D99" in the present invention are as follows.

[0024] <Method for Measuring Particle Size> The particle size of the first raw material particles and the particle size of the raw material precursor particles in the present invention mean 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. The measurement of the particle size was performed using a laser diffraction / scattering particle size distribution analyzer "Product Name: LA-960" manufactured by HORIBA Ltd. Regarding the raw material precursor particles classified by a sieve, the range of the aperture diameter of the sieve used for classification is taken as the range of the particle size.

[0025] <Methods for Measuring D70, D60, D50, D90, and D99> "D70" is the 70% diameter in the volume-based integrated fraction obtained by measuring the particle size by the laser diffraction method. "D60" is the 60% diameter in the volume-based integrated fraction obtained by measuring the particle size by the laser diffraction method. "D50" is the 50% diameter in the volume-based integrated fraction obtained by measuring the particle size by the laser diffraction method. "D90" is the 90% diameter in the volume-based integrated fraction obtained by measuring the particle size by the laser diffraction method. "D99" is the 99% diameter in the volume-based integrated fraction obtained by measuring the particle size by the laser diffraction method.

[0026] Hereinafter, referring to the drawings, a method for manufacturing a glass product according to an embodiment will be described. Figure 1 is a flowchart 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 later. As shown in Figure 1, the manufacturing method of the glass product in this embodiment includes a dissolution step S4 for dissolving the glass raw material composition and a molding and solidification step S5.

[0027] "Dissolution process S4" In the dissolution process S4, the glass raw material composition is dissolved to form molten glass. The glass raw material composition includes a first raw material particle and a plurality of raw material particles having different components from the first raw material particle. In this embodiment, the plurality of raw material particles include a second raw material particle and a third raw material particle.

[0028] Furthermore, the glass raw material composition preferably contains, along with the first raw material particles, second raw material particles, and third raw material particles, other raw materials known as glass raw materials other than the first raw material particles, second raw material particles, and third raw material particles, to the extent that they do not impair the effects of the present invention. Specifically, it is preferable that the other raw materials include one or more selected from aluminum oxide particles, alkali metal sources, alkaline earth metal sources, and boron sources.

[0029] Furthermore, the glass raw material composition may optionally contain one or more other raw materials selected from tin oxide, titanium oxide, zirconium oxide, zircon, cerium oxide, antimony oxide, iron oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, etc., to the extent that it does not impair the effects of the present invention.

[0030] (first raw material particles) The first raw material particles are the raw materials for SiO2, Al2O3, and Na2O contained in the glass raw material composition. The first raw material particles have an SiO2 content of 30% to 70% by mass, an Al2O3 content of 20% to 60% by mass, and a Na2O content of 0% to 10% by mass.

[0031] In the glass product manufacturing method of this embodiment, since the SiO2, Al2O3, and Na2O content in the first raw material particles is within the above range, the desoda-de-soda agent, which is waste separated from the calcined product containing alumina in the alumina manufacturing process, can be used as the first raw material particles. The above desoda-de-soda agent is a by-product produced by the reaction accompanying the calcination to generate alumina, and has a core-shell structure having a core portion with an SiO2 content of 90% by mass or more, and a shell portion formed to cover the core portion, with an Al2O3 content of 85% by mass or more and containing Na2O.

[0032] In the glass product manufacturing method of this embodiment, in order to obtain preferred first raw material particles, it is preferable to perform the "raw material precursor particle manufacturing process S11" and the "raw material precursor particle classification process S12" before the dissolution process, as shown in Figure 1. 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 above-mentioned desoda removal agent, which is waste generated in the alumina manufacturing process, is used as the first raw material particles, the "raw material precursor particle manufacturing process S11" and the "raw material precursor particle classification process S12" do not need to be performed.

[0033] "Raw material precursor particle manufacturing process S11" In the raw material precursor particle manufacturing step S11, raw material precursor particles, which are the raw materials for the first raw material particles, are manufactured. As the raw material precursor particles, a desodium oxidizing agent separated from the calcined product containing alumina produced in the alumina manufacturing process can be used. Therefore, the raw material precursor particle manufacturing step S11 can be a part of the alumina manufacturing process.

[0034] In the raw material precursor particle manufacturing process S11, first, bauxite is dissolved in an aqueous sodium hydroxide solution to obtain an aqueous sodium aluminate solution. Next, the obtained sodium aluminate is hydrolyzed to obtain aluminum hydroxide. Then, a mixture containing the obtained aluminum hydroxide and silica sand as a soda removal agent is calcined to produce a calcined product containing Al2O3. After that, Al2O3 is separated from the obtained calcined product to produce raw material precursor particles. The raw material precursor particles manufactured in this way may inevitably contain Na2O, which originates from the sodium component in the aqueous sodium hydroxide solution used in the alumina manufacturing process.

[0035] The mixture produced in the raw material precursor particle manufacturing process S11 preferably contains 70% to 95% by mass of aluminum hydroxide and 5% to 30% by mass of silica sand.

[0036] Furthermore, the calcination of the mixture produced in the raw material precursor particle production process S11 can be carried out using a known method, similar to the method used in the alumina production process when a mixture of aluminum hydroxide and silica sand as a desorizing agent is calcined. Specifically, a method of heating at a temperature of 1000°C to 1400°C for 10 minutes to 10 hours can be used.

[0037] Furthermore, as a method for separating Al2O3 from the calcined product to obtain raw material precursor particles, known methods similar to those used in the alumina manufacturing process for separating the desoda-removing agent from the calcined product containing alumina can be used. Specifically, methods such as classification and separation using a dry classifier such as a sieving machine can be used.

[0038] "Raw material precursor particle classification step S12" If the raw material precursor particles obtained in the raw material precursor particle manufacturing process S11 are a soda-de-soda agent separated from a calcined product containing alumina produced in the alumina manufacturing process, the raw material precursor particles have the core-shell structure described above.

[0039] The particles having a core-shell structure that form the above-mentioned soda-removing agent show little difference in shell thickness due to differences in particle size. More specifically, the shell thickness is about 200 μm and is approximately constant regardless of the particle size of the particles having a core-shell structure. Therefore, the ratio of shell thickness to particle size of the raw material precursor particles is smaller as the particle size of the raw material precursor particles increases. Consequently, the raw material precursor particles and the first raw material particles obtained by classifying the raw material precursor particles have a higher SiO2 content and lower Al2O3 and Na2O content as the particle size increases, and the greater the variation in particle size, the greater the variation in composition.

[0040] In the raw material precursor particle classification step S12, the raw material precursor particles are classified to obtain first raw material particles from which larger particle sizes have been removed. Since the first raw material particles obtained in this way do not contain larger particle sizes, they have a lower SiO2 content and a higher proportion of Al2O3 and Na2O compared to the raw material precursor particles. Therefore, by including the first raw material particles in the glass raw material composition, the proportion of Al2O3 contained in the first raw material particles in the total Al2O3 contained in the glass raw material composition can be increased. This makes it easier to increase the content of recycled raw materials in the raw materials of glass products when the raw material precursor particles are the above-mentioned desoda-removing agent, which is waste. Furthermore, since the first raw material particles do not contain larger particle sizes, the composition variation is reduced and the solubility is improved, which is preferable.

[0041] Specifically, the first raw material particles are preferably particles with a D70 or lower ratio obtained by classifying raw material precursor particles into particles with a D70 or higher ratio and particles with a D70 or lower ratio.

[0042] Furthermore, it is more preferable that the first raw material particles are particles with a D60 or lower, obtained by classifying the raw material precursor particles into particles with a D60 or higher and particles with a D60 or lower. Compared to the case where the first raw material particles are particles with a D70 or lower, the first raw material particles obtained in this way have a lower SiO2 content, a higher Al2O3 content, higher compositional uniformity, and better solubility.

[0043] Furthermore, it is more preferable that the first raw material particles are particles with a D50 or lower ratio of the raw material precursor particles, obtained by classifying the raw material precursor particles into particles with a D50 or higher ratio and particles with a D50 or lower ratio of the raw material precursor particles. Compared to the case where the first raw material particles are particles with a D60 or lower ratio of the raw material precursor particles, the first raw material particles obtained in this way have a lower SiO2 content, a higher Al2O3 content, even greater uniformity of composition, and better solubility.

[0044] Furthermore, in the raw material precursor particle classification step S12, it is preferable to produce first raw material particles with a particle diameter of 1400 μm or less by classifying the raw material precursor particles. When the particle diameter of the first raw material particles is 1400 μm or less, it does not contain raw material precursor particles with a large particle diameter, resulting in a low SiO2 content, a high Al2O3 content, less variation in composition, and good solubility.

[0045] In the raw material precursor particle classification step S12, it is preferable to classify the raw material precursor particles to obtain first raw material particles with a particle diameter of 1400 μm or less, more preferably first raw material particles with a particle diameter of 1180 μm or less, even more preferably first raw material particles with a particle diameter of 1000 μm or less, and particularly preferably first raw material particles with a particle diameter of 850 μm or less. The reason for this is that when the raw material precursor particles are the above-mentioned desodium ionizing agent which is waste, the SiO2 content is low, the Al2O3 content is high, the composition is highly uniform, and the solubility is good.

[0046] Furthermore, it is more preferable that the first raw material particles are raw material precursor particles with a diameter of 1400 μm or less, obtained by classifying the raw material precursor particles into particles with a diameter of more than 1400 μm and particles with a diameter of 1400 μm or less. The first raw material particles obtained in this way 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 good solubility.

[0047] Furthermore, it is more preferable that the first raw material particles are raw material precursor particles with a diameter of 1180 μm or less, obtained by classifying the raw material precursor particles into particles with a diameter greater than 1180 μm and particles with a diameter of 1180 μm or less. The first raw material particles obtained in this way 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 even greater uniformity of composition and good solubility.

[0048] Furthermore, it is more preferable that the first raw material particles are raw material precursor particles smaller than 1000 μm, obtained by classifying the raw material precursor particles into particles larger than 1000 μm and particles smaller than 1000 μm. The first raw material particles thus obtained contain 20% to 50% by mass of SiO2, 35% to 75% by mass of Al2O3, and 2% to 7% by mass of Na2O, and have good solubility.

[0049] Furthermore, it is more preferable that the first raw material particles are raw material precursor particles with a diameter of 850 μm or less, obtained by classifying the raw material precursor particles into particles with a diameter of more than 850 μm and particles with a diameter of 850 μm or less. The first raw material particles obtained in this way 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 even greater uniformity of composition and good solubility.

[0050] In the raw material precursor particle classification step S12, known methods can be used to classify the raw material precursor particles, such as using a filter, such as a sieve; using gravity, which takes advantage of differences in falling velocity and falling position based on particle size; using centrifugal force, such as a cyclone type; and using inertial force.

[0051] When the raw material precursor particles are a desoda-removing agent separated from a calcined product containing alumina produced in the alumina manufacturing process, the first raw material particles obtained in the raw material precursor particle classification step S12 have a core-shell structure having a core portion with an SiO2 content of 90% by mass or more, and a shell portion formed to cover the core portion, having an Al2O3 content of 90% by mass or more and containing Na2O, and the ratio of the thickness of the shell portion to the particle diameter of the first raw material particles is smaller as the particle diameter of the first raw material particles increases. Furthermore, when the raw material precursor particles are the above-mentioned desoda-removing agent, the first raw material particles may have a core-shell structure in which the thickness of the shell is substantially uniform.

[0052] (Second raw material particles) In the glass product manufacturing method of this embodiment, second raw material particles are prepared before the melting process (second raw material particle preparation step S2). The second raw material particles are SiO2 raw materials contained in the glass raw material composition. In the glass product manufacturing method of this embodiment, commercially available silica sand may be used as the second raw material particles. 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 results in a glass raw material composition with good solubility.

[0053] The second raw material particles preferably have a D90 of 100 μm or more. When the D90 of the second raw material particles is 100 μm or more, the variation in particle size between the second raw material particles and the first raw material particles tends to be small. As a result, the solubility when dissolving the glass raw material composition in the dissolution process S4 is improved, and glass products with even less variation in quality can be manufactured. The D90 of the second raw material particles is more preferably 300 μm or more, even more preferably 450 μm or more, and particularly preferably 600 μm or more.

[0054] Furthermore, the second raw material particles preferably have a D90 of 2000 μm or less. When the D90 of the second raw material particles is 2000 μm or less, the solubility when dissolving the glass raw material composition tends to be better. The second raw material particles are more preferably 1400 μm or less in D90, even more preferably 1180 μm or less, even more preferably 1000 μm or less, and particularly preferably 800 μm or less.

[0055] (Third raw material particles) In the glass product manufacturing method of this embodiment, third raw material particles are prepared before the melting process (third raw material particle preparation step S3). The third raw material particle is the raw material particle with the largest D50 among the multiple raw material particles contained in the glass raw material composition. The third raw material particle has a different composition from the first and second raw material particles. Examples of the third raw material particle include particles made of potassium carbonate or sodium carbonate. The third raw material particle may be a coarse particle with a D50 of 350 μm to 550 μm and a D90 of 550 μm to 850 μm.

[0056] As described above, the third raw material particle is the coarsest particle with the largest D50 value among the multiple raw material particles contained in the glass raw material composition. In this embodiment, it is preferable to classify the raw material precursor particles that will become the first raw material particle based on the D99 value of the third raw material particle, which is the coarse particle.

[0057] Specifically, it is preferable that the first raw material particles are particles of the third raw material particle with a D of 99 or less, obtained by classifying the raw material precursor particles into particles of the third raw material particle with a D of greater than 99 and particles of the third raw material particle with a D of 99 or less. The reason for this is that since there are no first raw material particles with large particle sizes, it is possible to manufacture glass products with less variation in quality. It is even more preferable that the first raw material particles are particles of the third raw material particle with a D of 90 or less, obtained by classifying the raw material precursor particles into particles of the third raw material particle with a D of greater than 90 and particles of the third raw material particle with a D of 90 or less.

[0058] (Aluminum oxide particles) As for the aluminum oxide (Al2O3) particles, it is preferable to use those with a D90 of 150 μm or less, more preferably 100 μm or less, even more preferably 90 μm or less, and particularly preferably 85 μm or less. Aluminum oxide particles do not need to be included in the glass raw material composition if the Al2O3 contained in the first raw material particles brings the total Al2O3 content in the glass raw material composition within the target glass composition range.

[0059] (Alkali metal source) The alkali metal source is a compound that melts to form Na2O, K2O, and Li2O. The particle size of the alkali metal source is not particularly limited, and known alkali metal sources can be used. Examples of alkali metal sources include alkali metal carbonates, sulfates, nitrates, oxides, hydroxides, chlorides, and fluorides. In this invention, alkali metals refer to Na, K, and Li. Only one alkali metal source may be used, or two or more may be used in combination. Examples of alkali metal carbonates include sodium carbonate, potassium carbonate, and lithium carbonate, and sodium carbonate (soda ash) is particularly suitable in terms of ease of handling. The alkali metal source does not need to be included in the glass raw material composition if the Na2O contained in the first raw material particles brings the total Na2O content in the glass raw material composition within the range of the target glass composition.

[0060] (Alkaline earth metal source) Alkaline earth metal sources are compounds that form MgO, CaO, BaO, and SrO upon melting, and are included as needed. Examples of alkaline earth metal sources include alkaline earth metal carbonates, sulfates, nitrates, oxides, hydroxides, chlorides, and fluorides. In this specification, alkaline earth metals refer to Mg, Ca, Ba, and Sr. Alkaline earth metal sources may be used individually or in combination of two or more. The particle size of the alkaline earth metal source is not particularly limited, and known alkaline earth metal sources can be used. In addition, complex carbonates such as dolomite and complex oxides such as calcined dolomite can also be used.

[0061] (Boron source) Examples of boron sources include boric acid, boric acid oxide (B2O3), and colemanite. Only one boron source may be used, or two or more may be used in combination. Examples of boric acid include orthoboric acid (H3BO3), metaboric acid (HBO2), and tetraboric acid (H2B4O7).

[0062] (Composition of glass raw material composition) The glass raw material composition preferably has a glass composition in which, on an oxide basis, the SiO2 content is 45% by mass or more, the Al2O3 content is 5% by mass or more, and the total content of Li2O, Na2O, and K2O is 5% by mass or more.

[0063] The glass raw material composition is prepared by mixing the first raw material particles, the second raw material particles, the third raw material particles, and other raw materials as needed, to achieve the target glass composition. The glass composition of the glass raw material composition is adjusted so that, in terms of oxides, it is approximately the same as the glass composition of the target glass product, excluding components that are easily volatile during melting. The glass raw material composition may also contain clarifying agents and oxides that have a clarifying effect as volatile components.

[0064] In this embodiment, the content of first raw material particles in the glass raw material composition is 2% by mass or more. Therefore, when the first raw material particles are the above-mentioned desoda-removing agent which is waste, a glass product with a sufficiently high content of recycled raw materials can be obtained. The content of first raw material particles 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 is possible to increase the content of recycled raw materials in the glass product. Furthermore, the content of first raw material particles in the glass raw material composition is preferably 35% by mass or less, and more preferably 25% by mass or less. This is because it is possible to obtain a glass product with even less variation in quality.

[0065] In this embodiment, preferred glass and crystallized glass compositions (total 100% by mass) of the glass raw material composition include, for example, the following compositions (1) to (5). Composition (1): SiO2 is 45-75% by mass, Al2O3 is 5-30% by mass, B2O3 is 0-20% by mass, the total of Li2O, Na2O, and K2O is 5-35% by mass, and the total of MgO, CaO, SrO, and BaO is 0-20% by mass. Composition (2): SiO2 is 45-75% by mass, Al2O3 is 7-30% by mass, B2O3 is 0-20% by mass, the total of Li2O, Na2O, and K2O is 5-35% by mass, and the total of MgO, CaO, SrO, and BaO is 0-20% by mass. Composition (3): SiO2 is 45-75% by mass, Al2O3 is 7-30% by mass, B2O3 is 0-20% by mass, Li2O is substantially absent, the total of Na2O and K2O is 5-35% by mass, and the total of MgO, CaO, SrO, and BaO is 0-20% by mass. Composition (4): SiO2 is 45-75% by mass, Al2O3 is 7-30% by mass, B2O3 is 0-20% by mass, Li2O is 1-20% by mass, the total of Li2O, Na2O, and K2O is 5-35% by mass, and the total of MgO, CaO, SrO, and BaO is 0-20% by mass. Composition (5): SiO2 is 45-75% by mass, Al2O3 is 7-30% by mass, B2O3 is 0-20% by mass, Li2O is 1-20% by mass, the total of Li2O, Na2O, and K2O is 5-35% by mass, and the total of MgO, CaO, SrO, and BaO is 0-20% by mass, and the content of Co3O4 or NiO, TiO2, Cr2O3, MnO2, and MoO3 is 0.0001-5% by mass.

[0066] (Melting method) Known methods can be used to melt the glass raw material composition to produce molten glass. Preferably, a method is used in which the glass raw material composition is placed in a melting furnace and melted. The melting furnace used to melt the glass raw material composition is not particularly limited and may be a batch type or a continuous type. For example, the glass raw material composition and, if necessary, cullet having the same glass composition as the target glass product are continuously fed into the melting furnace and heated to about 1400 to 1700°C to melt and produce molten glass. Cullet is glass waste discharged during the glass manufacturing process.

[0067] "Forming / solidification process S5" The molding and solidification step S5 involves molding the molten glass produced in the melting step S4 into a predetermined shape and solidifying it by slow cooling as necessary. In the molding and solidification step S5 of this embodiment, known methods such as the float method, down-draw method, and fusion method can be used to mold the molten glass into a predetermined shape. The molten glass produced in the melting step S4 can also be molded using methods such as press molding or blow molding. Furthermore, a method of molding the molten glass on a fiber may be used. Subsequently, post-processing is performed as needed using known methods such as cutting and polishing. This yields the glass product of this embodiment.

[0068] The glass product manufacturing method of this embodiment is a method for manufacturing a glass product having a predetermined glass composition, and involves dissolving a glass raw material composition that contains 10% by mass or more of first raw material particles having an SiO2 content of 30% to 70% by mass, an Al2O3 content of 20% to 60% by mass, and a Na2O content of 0% to 10% by mass, as well as multiple raw material particles with different components from the first raw material particles. Therefore, by using a desodium filtration agent separated from alumina-containing calcined product in the alumina manufacturing process, or particles obtained by classifying the desodium filtration agent, as the first raw material particles, the content of recycled raw materials in the raw materials of the glass product can be increased, and glass products with less variation in quality can be manufactured.

[0069] The glass product manufacturing method of this embodiment is a method for manufacturing glass products using a glass raw material composition containing a soda-removing agent, which is a recycled raw material. The objective of this embodiment is to provide a glass product manufacturing method that can produce glass products with a sufficiently high recycled raw material content and low variation in quality. The glass product manufactured using recycled raw materials by the manufacturing method of this embodiment can be, for example, plate glass. The glass product manufactured using the manufacturing method of this embodiment is not limited to plate glass, but may also be, for example, glass bottles, glass blocks, glass beads, etc. Furthermore, the glass obtained by melting in the manufacturing method of this embodiment may be subjected to heat treatment to become crystallized glass or phase-separated glass. [Examples]

[0070] The present invention will be described in more detail below using examples. However, the present invention is not limited to these examples.

[0071] (raw material precursor particles) As raw material precursor particles, a desodium oxidizing agent (C1) separated from calcined alumina produced during the alumina manufacturing process was prepared. The raw material precursor particles were analyzed for particle shape and elemental composition using an electron probe microanalyzer (EPMA) (product name: JXA-8230; manufactured by JEOL) under the conditions described below. The results are shown in Figures 2 to 4.

[0072] Samples were prepared by embedding raw material precursor particles in resin and polishing the surface until the raw material precursor particles were exposed. The surface of the obtained samples was coated with platinum at a density of approximately 30 nm by sputtering and subjected to EPMA analysis. EPMA was performed under the following conditions: acceleration voltage 15 kV, probe current 50 nA, probe diameter 1 μmφ, step interval 10 μm, and measurement time 10 ms. Characteristic X-ray count mappings were obtained for SiO2, Al2O3, and Na2O, respectively.

[0073] Figure 2 is a photograph showing the analysis results of one raw material precursor particle. Figures 3 and 4 are photographs showing the analysis results of multiple raw material precursor particles. Figures 2(a), 3(a), and 4(a) are photographs of backscattered electron images. Figures 2(b), 3(b), and 4(b) are photographs showing the surface analysis (mapping analysis) results of SiO2. Figures 2(c), 3(c), and 4(c) are photographs showing the surface analysis (mapping analysis) results of Al2O3. Figures 2(d), 3(d), and 4(d) are photographs showing the surface analysis (mapping analysis) results of Na2O.

[0074] As shown in Figures 2 to 4, the raw material precursor particles, which are desodium removers separated from calcined alumina-containing products produced in the alumina manufacturing process, were found to have a core-shell structure consisting of a core portion with an SiO2 content of 90% by mass or more and a shell portion formed to cover the core portion with an Al2O3 content of 85% by mass or more. Furthermore, in the raw material precursor particles shown in Figures 2 to 4, the difference in the thickness of the shell portion of the core-shell structure due to differences in particle size was small, and the thickness of the shell portion was approximately constant.

[0075] Furthermore, from the results of surface analysis (mapping analysis) of the raw material precursor particles shown in FIGS. 2 to 4, it was confirmed that the raw material precursor particles had a core-shell structure having a shell portion rich in Al2O3. Therefore, using the Al surface analysis results of the scanning electron microscope (SEM) images by EPMA, the thickness of the region where Al was detected was measured by the method shown below and taken as the shell thickness. As a result, the thicknesses of the shell portions of the raw material precursor particles shown in FIGS. 2 to 4 were all about 200 μm.

[0076] <Measurement of the thickness of the shell portion> The magnification of the SEM image was adjusted to 200 to 400 times so that a plurality of raw material precursor particles were within one field of view. Five particles in which a ring-shaped region containing Al was observed along the outer periphery were selected from the obtained SEM images. Then, for the ring-shaped region containing Al in each particle, the thicknesses in four places spaced at equal intervals along the outer periphery in the direction from the outer periphery to the center were measured, and the average value was calculated and taken as the thickness of the Al region. The average value of the thicknesses of the Al regions of the five raw material precursor particles obtained in this way was calculated and taken as the thickness of the shell portion.

[0077] (First raw material particles) As raw material precursor particles, different (A1) to (C1) desoda agents separated from a fired product containing alumina, which were produced in the alumina production process, were prepared. For each of the desoda agents (A1) to (C1), the contents of SiO2, Al2O3, and Na2O were measured by the method shown below. The results are shown in Table 1.

[0078] <Measurement of the contents of SiO2, Al2O3, and Na2O> Regarding the composition of the desoda agent, it was evaluated by the XRF (X-ray Fluorescence Spectrometer) method. The analysis conditions for the XRF method were as follows. As the XRF measuring device, ZSX PrimusII manufactured by Rigaku Corporation was used. The content of each component was calculated from the obtained fluorescence X-ray peaks using the Fundamental Parameter method.

[0079] (Analysis conditions) Output: Rh 50kV-72mA Filter: OUT ⇒ Ni400 Attenuator: 1 / 1 Slit: Std. Spectroscopic crystal: RX25 ⇒ LiF(200) Detector: PC PHA:110-450

[0080] [Table 1]

[0081] The errors shown in Table 1 were calculated by preparing five samples for each desodium saturates and calculating the standard deviation of their measurement results. As shown in Table 1, the desodium removers (A1) to (C1) all contained SiO2 in the range of 30% to 70% by mass, Al2O3 in the range of 20% to 60% by mass, and Na2O in the range of 0% to 10% by mass.

[0082] Next, the desodium ionizer (A1) was classified by the method shown below. For each particle size range of the desodium ionizer (A1) after classification, the SiO2, Al2O3, and Na2O content was measured in the same manner as for the desodium ionizer (A1) before classification. The results are shown in Table 2.

[0083] <Classification method 1> 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 order of increasing mesh size, and the unclassified desodium sieve was placed on top of the 1400 μm sieve, and the sieve was vibrated. This classified the unclassified desodium sieve into particles with particle sizes in the following ranges: 1400 μm or more, less than 1180 μm; 1000 μm or more, less than 1000 μm; 850 μm or more, less than 850 μm; 710 μm or more, less than 710 μm.

[0084] [Table 2]

[0085] <Classification method 2> Sieves with aperture sizes of 1400 μm, 1180 μm, 1000 μm, and 850 μm were prepared. The desodium sieve before classification was placed on each sieve, and the sieves were vibrated. This classified the desodium sieve before classification into particles with particle sizes of less than 1400 μm, less than 1180 μm, less than 1000 μm, and less than 850 μm.

[0086] [Table 3]

[0087] The errors shown in Tables 2 and 3 were calculated by preparing five samples for each desodium evaporator with different particle sizes and calculating the standard deviation of their measurement results. As shown in Tables 2 and 3, it was confirmed that the SiO2, Al2O3, and Na2O content of the (A1) desodium remover differed depending on the particle size. More specifically, it was found that the smaller the particle size of the (A1) desodium remover, the lower the SiO2 content and the higher the Al2O3 and Na2O content tended to be.

[0088] This revealed that the desodium agent (A1) has less variation in composition by limiting the particle size to a specific range. Therefore, it was found that the desodium agent (A1) can reduce variation in composition by performing a top cut to remove larger particles and narrowing the range of particle size variation.

[0089] (Second raw material particles) As second raw material particles, silica sand A and silica sand B were prepared, and their particle sizes were measured using the same method as for measuring the particle size of the first raw material particles described above, and D50 and D90 were calculated. The results are shown below. Silica sand A: D90=946μm, D50=559μm Silica sand C: D90=470μm, D50=262μm

[0090] (Third raw material particles) The particle sizes of potassium carbonate particles and sodium carbonate particles, which are raw material particles with different compositions from the first and second raw material particles, were measured using the same method as for measuring the particle size of the first raw material particles. The results are shown in Table 4.

[0091] [Table 4] [Explanation of Symbols]

[0092] S11 Raw material precursor particle manufacturing process, S12 Raw material precursor particle classification process, S2 2nd raw material particle preparation process, S3 3rd raw material particle preparation process, S4 melting process, S5 molding / solidification process.

Claims

1. SiO ２ Al ２ O ３ Na ２ A method for producing glass products having a glass composition containing O, SiO ２ The content is 20% to 70% by mass. Al ２ O ３ The content is 20% to 75% by mass. Na ２ A method for producing glass products, comprising dissolving a glass raw material composition containing 2% by mass or more of first raw material particles having an O content of 0% by mass to 10% by mass, and also containing a plurality of raw material particles having different components from the first raw material particles.

2. Based on the oxide, the content of SiO ２ is 45% by mass or more, Al ２ O ３ The content is 5% by mass or more. Li ２ O, Na ２ O, K ２ A method for producing a glass product according to claim 1, comprising producing a glass product having a glass composition in which the total content of oxygen is 5% by mass or more.

3. The method for manufacturing a glass product according to claim 1, wherein the first raw material particles are particles of raw material precursor particles with a D of 70 or less, obtained by classifying the raw material precursor particles into particles of the raw material precursor particles with a D of greater than 70 and particles of the raw material precursor particles with a D of 70 or less.

4. The method for manufacturing a glass product according to claim 1, wherein the first raw material particles are particles of raw material precursor particles with a D of 60 or less, obtained by classifying the raw material precursor particles into particles of the raw material precursor particles with a D of greater than 60 and particles of the raw material precursor particles with a D of 60 or less.

5. The method for manufacturing a glass product according to claim 1, wherein the first raw material particles are particles of raw material precursor particles with a D50 or less, obtained by classifying the raw material precursor particles into particles of the raw material precursor particles with a D50 or more and particles of the raw material precursor particles with a D50 or less.

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

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

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

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

10. The glass raw material composition comprises a second raw material particle, The method for manufacturing a glass product according to claim 1, wherein the second raw material particle is silica sand with a D90 of 2000 μm or less.

11. The method for producing a glass product according to claim 10, wherein the second raw material particle is silica sand with a D90 of 100 μm or more.

12. The glass raw material composition comprises the raw material particle with the largest D50 among the plurality of raw material particles, and a third raw material particle whose composition differs from that of the first and second raw material particles. The method for manufacturing a glass product according to claim 10, wherein the first raw material particles are particles of the third raw material with a D of 99 or less, obtained by classifying raw material precursor particles into particles of the third raw material with a D of greater than 99 and particles of the third raw material with a D of 99 or less.

13. The first raw material particles are SiO ２ A core portion having a content of 90% by mass or more, Formed to cover the core portion, Al ２ O ３ A method for manufacturing a glass product according to claim 1, comprising a core-shell structure having a shell portion having a content of 90% by mass or more of the same substance.

14. The method for manufacturing a glass product according to claim 13, wherein the ratio of the thickness of the shell portion to the particle diameter of the first raw material particles is smaller as the particle diameter of the first raw material particles increases.

15. By hydrolyzing sodium aluminate obtained by dissolving bauxite in an aqueous sodium hydroxide solution, and then calcining the resulting mixture containing aluminum hydroxide and silica sand, Al ２ O ３ A calcined product containing Al is produced from the calcined product. ２ O ３ A method for manufacturing a glass product according to claim 1, comprising: separating to produce raw material precursor particles; and classifying the raw material precursor particles to obtain first raw material particles from which particles with a larger particle size have been removed.

16. The method for producing a glass product according to claim 1, wherein the first raw material particles are a soda-removing agent separated from a calcined product containing alumina in the alumina manufacturing process.

17. The method for manufacturing a glass product according to claim 1, wherein the first raw material particles have a core-shell structure in which the thickness of the shell is substantially uniform.

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