Method for producing glass, mixture, dried product, and glass

Abstract

The present invention relates to a method for producing glass that includes: obtaining a mixture comprising a glass powder containing at least one heavy metal oxide selected from Sb2O3, PbO, and As2O3, a reducing agent, and a liquid medium, where the reducing agent is dissolved in the liquid medium; and heating the mixture at a temperature of 700°C or higher.

Description

Glass manufacturing method, mixture, dried product, and glass

[0001] The present invention relates to a method for producing glass, a mixture, a dried product, and glass.

[0002] Normally, a lot of CO is produced during glass manufacturing. ２ This is mainly due to the combustion of heavy oil in the melting of glass raw materials and the decomposition of carbonate raw materials. ２ In order to reduce the amount of waste, it is useful to produce glass by reusing glass cullet. As a method for reusing glass cullet, for example, Patent Document 1 discloses a glass recycling method that can improve the value of the cullet of reused non-crystallized glass. Also, for example, Patent Document 2 discloses a glass plate reprocessing method for effectively reusing glass plates such as tempered glass substrates used in solar cell panels, and a solar cell panel recycling method.

[0003] Japanese Patent Publication No. 2021-109122 Japanese Patent Publication No. 2021-151634

[0004] As described in the above document, glass cullet includes PV cullet obtained by crushing solar panels. Currently, most of the PV cullet is landfilled, so there is a strong social demand for the reuse of PV cullet. However, PV cullet contains Sb to adjust the Fe-Redox (oxidation-reduction state of Fe). ２ O ３ However, glass containing such heavy metal oxides is reduced during the float process, resulting in coloration and cloudiness. ２ O ３ It is necessary to reduce the amount of heavy metal oxides such as those mentioned above, but such methods have not been thoroughly investigated so far.

[0005] The present invention has been made in view of the above circumstances, and ２ O ３The present invention aims to provide a method for producing glass that can reduce the amount of heavy metal oxides when producing new glass using glass containing such heavy metal oxides.

[0006] As a result of extensive research, the present inventors have found that Sb ２ O ３ The present inventors have found that, in a mixture containing a glass powder containing heavy metal oxides such as those mentioned above, a reducing agent, and a liquid medium, the amount of heavy metal oxides in the resulting glass can be reduced by heating the mixture in a state in which the reducing agent is dissolved in the liquid medium, and have completed the present invention.

[0007] That is, one aspect of the present invention is Sb ２ O ３ , PbO, and As ２ O ３ The present invention relates to a method for producing glass, the method comprising: obtaining a mixture containing glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder, a reducing agent, and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; and heating the mixture at a temperature of 700°C or higher.

[0008] Another aspect of the present invention is Sb ２ O ３ , PbO, and As ２ O ３ The present invention relates to a method for producing glass, the method comprising: obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent; and heating the dried product at a temperature of 700°C or higher.

[0009] Another aspect of the present invention is Sb ２ O ３ , PbO, and As ２ O ３The present invention relates to a method for producing glass, the method comprising: obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent; and mixing the dried product with a halogenating agent and heating the mixture at a temperature of 700°C or higher.

[0010] Another aspect of the present invention is Sb ２ O ３ , PbO, and As ２ O ３ The present invention relates to a mixture comprising a glass powder containing at least one heavy metal oxide selected from the group consisting of: a reducing agent; and a liquid medium, wherein the reducing agent is dissolved in the liquid medium.

[0011] Another aspect of the present invention is a dried product obtained by drying a mixture, wherein the mixture contains Sb ２ O ３ , PbO, and As ２ O ３ The present invention relates to a dried material comprising a glass powder containing at least one heavy metal oxide selected from the group consisting of: a reducing agent; and a liquid medium, wherein the reducing agent is dissolved in the liquid medium.

[0012] In another aspect of the present invention, the content in mass% on an oxide basis is SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0 to 10%, heavy metal oxides: 0.001 to 0.15%, and halogen elements: 0.005 to 3%, and the content of the heavy metal oxides is ２ O ３ , PbO, and As ２ O ３ The content of the halogen elements in the glass means the total amount of F, Cl, and Br.

[0013] According to the present invention, Sb ２ O ３When new glass is produced using glass containing heavy metal oxides such as those mentioned above, the amount of the heavy metal oxides can be reduced, thereby making it possible to suppress the occurrence of coloration and whitish haze in the resulting glass, which are caused by heavy metal oxides.

[0014] Fig. 1(a) is a diagram showing an example of a flowchart for a first manufacturing method of the present invention. Fig. 1(b) is a diagram showing an example of a flowchart for a second manufacturing method of the present invention. Fig. 1(c) is a diagram showing an example of a flowchart for a third manufacturing method of the present invention. Fig. 2(a) is a diagram showing an example of a preferred flowchart for the first manufacturing method of the present invention. Fig. 2(b) is a diagram showing an example of a preferred flowchart for the second manufacturing method of the present invention. Fig. 2(c) is a diagram showing an example of a preferred flowchart for the third manufacturing method of the present invention.

[0015] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified as desired without departing from the gist of the present invention. Furthermore, the term "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. In this specification, the terms "glass," "glass powder," "glass material," and "glass raw material" are used with different meanings.

[0016] <Glass Manufacturing Method> A glass manufacturing method according to one embodiment of the present invention (hereinafter also referred to as the first manufacturing method) is a method for manufacturing a glass containing Sb ２ O ３ , PbO, and As ２ O ３ The method includes obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of (hereinafter also referred to as the heavy metal oxide of this embodiment), a reducing agent, and a liquid medium, wherein the reducing agent is dissolved in the liquid medium, and heating the mixture at a temperature of 700° C. or higher. Preferably, the mixture further contains a halogenating agent, and it is also preferable to heat the mixture at a temperature of 1000° C. or higher, and it is more preferable that the mixture further contains a halogenating agent and that the mixture be heated at a temperature of 1000° C. or higher.

[0017] In addition, a method for producing glass according to another embodiment of the present invention (hereinafter also referred to as the second production method) is a method for producing glass according to the present invention, ２ O ３ , PbO, and As ２ O ３ The method includes obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium, drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent, and heating the dried product at a temperature of 700° C. or higher. It is preferable that the mixture further contains a halogenating agent, and that the obtained dried product also contains the halogenating agent. It is also preferable that the dried product be heated at a temperature of 1000° C. or higher, and it is more preferable that the mixture further contains a halogenating agent and that the dried product be heated at a temperature of 1000° C. or higher.

[0018] In addition, a method for producing glass according to another embodiment of the present invention (hereinafter also referred to as the third production method) comprises adding Sb ２ O ３ , PbO, and As ２ O ３ The method includes obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium, drying the mixture to obtain a glass powder containing the heavy metal oxide and a dried material containing the reducing agent, and mixing the dried material with a halogenating agent and heating the mixture at a temperature of 700° C. or higher. It is preferable to heat the mixture of the dried material and halogenating agent at a temperature of 1000° C. or higher.

[0019] According to the first, second, and third manufacturing methods of this embodiment (hereinafter collectively referred to as the manufacturing methods of this embodiment), glass containing reduced amounts of heavy metal oxides can be obtained. This is presumably due to the following mechanism. In other words, the reducing agent is dissolved in a liquid medium in the mixture, allowing the reducing agent to be distributed substantially uniformly over the entire surface of the glass powder. In the subsequent heating step, the heavy metal oxide of this embodiment contained in the glass powder and the reducing agent can react efficiently to generate heavy metal fine particles. The heavy metal is then vaporized by heating, or the heavy metal is oxidized to a heavy metal oxide and then vaporized. Furthermore, when a halogenating agent is present, the heavy metal oxide reacts with the halogenating agent in the presence of the reducing agent, efficiently halogenating the heavy metal, and the halogenated heavy metal vaporizes upon heating. These reactions are believed to reduce the amount of heavy metal oxide in the resulting glass.

[0020] FIG. 1A shows an example of a flowchart of the first manufacturing method. FIG. 2A shows a preferred example of a flowchart of the first manufacturing method. In the first manufacturing method, first, Sb ２ O ３ , PbO, and As ２ O ３ A mixture is obtained (step S011), the mixture containing glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder, a reducing agent, and a liquid medium, with the reducing agent dissolved in the liquid medium. The obtained mixture is then heated at a temperature of 700°C or higher (step S012). In this manner, in the first manufacturing method, glass is obtained through the above two steps. Furthermore, in step S011, the mixture preferably further contains a halogenating agent in addition to the glass powder, the reducing agent, and the liquid medium (step S11). Furthermore, in step S012, the obtained mixture is preferably heated at a temperature of 1000°C or higher (step S12).

[0021] FIG. 1(b) shows an example of a flowchart of the second manufacturing method. FIG. 2(b) shows a preferred example of a flowchart of the second manufacturing method. In addition to the steps in the first manufacturing method, the second manufacturing method has a step of drying the mixture before the heating step. That is, in the second manufacturing method, first, Sb ２ O ３ , PbO, and As ２ O ３ A mixture is obtained containing a glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder, a reducing agent, and a liquid medium, with the reducing agent dissolved in the liquid medium (Step S021). The second manufacturing method then involves drying the obtained mixture before heating it to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent (Step S022). The obtained dried product is then heated at a temperature of 700°C or higher (Step S023). Thus, the second manufacturing method obtains glass through the above three steps. Furthermore, in Step S021, the mixture preferably further contains a halogenating agent in addition to the glass powder, reducing agent, and liquid medium (Step S21). That is, in Step S022, the dried product preferably further contains a halogenating agent in addition to the glass powder and reducing agent (Step S22). Furthermore, in Step S023, the obtained dried product is preferably heated at a temperature of 1000°C or higher (Step S23).

[0022] An example of a flowchart of the third production method is shown in FIG. 1(c). Also, a preferred example of a flowchart of the third production method is shown in FIG. 2(c). The third production method is similar to the second production method in that it includes a step of drying the mixture before the heating step, but differs in that the halogenating agent is added after the mixture is dried. That is, in the third production method, first, Sb ２ O ３ , PbO, and As ２ O ３A mixture is obtained containing a glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder, a reducing agent, and a liquid medium, with the reducing agent dissolved in the liquid medium (steps S031 and S31). The resulting mixture is then dried to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent (steps S032 and S32). The dried product is then mixed with a halogenating agent and heated at a temperature of 700°C or higher (step S033). In this way, the third manufacturing method obtains glass through the above three steps. Furthermore, in step S033, it is preferable to mix the dried product with a halogenating agent and heat the mixture at a temperature of 1000°C or higher (step S33).

[0023] Hereinafter, the manufacturing method of this embodiment will be described in detail for each step.

[0024] <Preparation of Mixture> In any of the first, second and third production methods, first, Sb ２ O ３ , PbO, and As ２ O ３ A mixture (hereinafter also referred to as the mixture of this embodiment) is obtained, which contains a glass powder containing at least one heavy metal oxide selected from the group consisting of: a reducing agent; and a liquid medium, wherein the reducing agent is dissolved in the liquid medium (steps S011, S021, S031). In the first and second manufacturing methods, it is preferable that the mixture further contains a halogenating agent (steps S11, S21).

[0025] (Glass powder) The glass powder is Sb ２ O ３ , PbO, and As ２ O ３ The glass powder containing at least one heavy metal oxide selected from the group consisting of Sb ２ O ３ , PbO, and As ２ O ３Alternatively, a glass powder obtained by pulverizing a glass material containing at least one heavy metal oxide selected from the group consisting of: using a ball mill, a vibration mill, etc. In the latter case, as described below, the glass material may be mixed with a reducing agent solution and an optional halogenating agent, or with a reducing agent, an optional halogenating agent, and a liquid medium, and then the glass material may be pulverized to obtain the glass powder.

[0026] The glass powder mainly targeted in this embodiment is Sb, which is obtained by crushing solar panels, as described in detail in the prior art section. ２ O ３ The glass powder is obtained by crushing PV cullet containing Sb. The main purpose of this embodiment is to manufacture new glass using crushed PV cullet. However, the manufacturing method of this embodiment is not limited to crushed PV cullet as the glass powder to be used, but is also applicable to glass powders of other origins and types. Furthermore, the heavy metal oxides of this embodiment include Sb ２ O ３ It is not only targeted at PbO and As from the viewpoint of removing harmful substances. ２ O ３ Heavy metal oxides include Sb ２ O ３ As well as PbO and As ２ O ３ Even in this case, the above-described mechanism applies, and therefore the amount of the heavy metal oxides in the glass obtained by the production method of this embodiment can be reduced.

[0027] That is, the glass powder is Sb ２ O ３ , PbO, and As ２ O ３ The glass powder contains at least one heavy metal oxide selected from the group consisting of Sb and Zn. ２ O ３ It is preferred that the compound contains:

[0028] In the first and second manufacturing methods of this embodiment, the content of the glass powder relative to the entire mixture is typically 40 to 99.9 mass%, preferably 55 to 95 mass%, and more preferably 70 to 90 mass%, from the viewpoint of efficiently promoting the reaction between the glass powder and the reducing agent and optional halogenating agent, and from the viewpoint of appropriately controlling the glass composition. Here, the content may be 40 mass% or more, preferably 55 mass% or more, more preferably 70 mass% or more, and may be 99.9 mass% or less, preferably 95 mass% or less, and more preferably 90 mass% or less. In the third manufacturing method, the content of the glass powder relative to the entire mixture is typically 40 to 99.9 mass%, preferably 60 to 98 mass%, and more preferably 75 to 95 mass%. Here, the content may be 40 mass% or more, preferably 60 mass% or more, more preferably 75 mass% or more, and may be 99.9 mass% or less, preferably 98 mass% or less, and more preferably 95 mass% or less.

[0029] In the mixture of the present embodiment in the first and second manufacturing methods, the total content of the heavy metal oxides of the present embodiment relative to the total glass powder, i.e., Sb ２ O ３ , PbO, and As ２ O ３ The total amount of the heavy metal oxides of the present embodiment relative to the total glass powder is typically 0.005 to 1 mass%, preferably 0.01 to 0.5 mass%, and more preferably 0.05 to 0.3 mass%. The total amount may be 0.005 mass% or more, preferably 0.01 mass% or more, and more preferably 0.05 mass% or more, and may be 1 mass% or less, preferably 0.5 mass% or less, and more preferably 0.3 mass% or less. In the mixture in the third production method, the total content of the heavy metal oxides of the present embodiment relative to the total glass powder is the same as above.

[0030] The median diameter d50 of the glass powder is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 10 μm or less, from the viewpoint of increasing the surface area of ​​the glass powder particles and promoting the reaction of the glass powder with the reducing agent and optional halogenating agent. The lower limit of the median diameter d50 is not particularly limited, but is, for example, 0.1 μm or more. The median diameter d50 means the particle size at 50% of the cumulative value in the particle size distribution determined by a laser diffraction / scattering method, and is measured using a laser diffraction / scattering particle size distribution measuring device (e.g., SALD-2300 manufactured by Shimadzu Corporation). The measurement is performed using a wet method in which the glass powder is dispersed in water, and agglomerates are previously broken down using ultrasound.

[0031] The glass composition of the glass powder will be described below. Note that the composition range of each component is expressed in mass % based on oxide unless otherwise specified.

[0032] The glass powder has a mass% oxide content of SiO ２ 60-80%, Na ２ O 5-20%, MgO 0-15%, CaO 5-20%, Al ２ O ３ 0 to 10%, heavy metal oxides 0.005 to 1% (the content of heavy metal oxides is Sb ２ O ３ , PbO, and As ２ O ３ When the glass powder is in the above range, the composition other than the heavy metal oxide of the glass obtained by the production method of the present embodiment can be easily adjusted to be close to the above range, and the content of the heavy metal oxide can be appropriately reduced.

[0033] In the glass powder, SiO ２ The content of SiO is preferably 60 to 80%. ２ contributes to improving the Young's modulus, making it easier to ensure that the strength required for automotive applications and the like is achieved in the resulting glass. ２ When the content of SiO is 60% or more, the weather resistance of the obtained glass can be easily ensured, and the average linear expansion coefficient does not become too large, so that the glass is less susceptible to thermal cracking.２ When the content is 80% or less, the viscosity of the glass does not increase too much when melted, and glass production is unlikely to become difficult.

[0034] SiO in glass powder ２ The content of SiO in the glass powder is more preferably 65% ​​or more, further preferably 68% or more, and particularly preferably 70% or more. ２ The content is more preferably 78% or less, further preferably 76% or less, and particularly preferably 74% or less.

[0035] In the glass powder, Na ２ The O content is preferably 5 to 20%. ２ O is a component that improves the melting property of glass. ２ By adding 5% or more of O, the viscosity of the glass is reduced, and the formability of the glass for vehicles, particularly the windshield, is improved. ２ The O content is more preferably 8% or more, further preferably 10% or more, and particularly preferably 12% or more. ２ When the O content is 20% or less, the average linear expansion coefficient does not become too large and the glass is less susceptible to thermal cracking. ２ The O content is more preferably 18% or less, further preferably 16% or less, and particularly preferably 14% or less.

[0036] The MgO content in the glass powder is preferably 0 to 15%. MgO is a component that promotes the dissolution of glass raw materials and improves weather resistance and Young's modulus. When the glass powder contains MgO, the MgO content is more preferably 1% or more, and even more preferably 2% or more. Furthermore, if the MgO content in the glass powder is 15% or less, devitrification is less likely to occur. The MgO content in the glass powder is more preferably 10% or less, even more preferably 7% or less, and particularly preferably 5% or less.

[0037] In the glass powder, the CaO content is preferably 5 to 20%. CaO is a component that improves the melting property of glass raw materials. The CaO content is more preferably 6% or more, and even more preferably 7% or more. Furthermore, by keeping the CaO content in the glass powder at 20% or less, an increase in the specific gravity of the glass is avoided, and low brittleness and strength are maintained. In order to prevent the glass from becoming brittle, the CaO content in the glass powder is more preferably 15% or less, even more preferably 12% or less, and particularly preferably 10% or less.

[0038] In the glass powder, Al ２ O ３ The content of Al is preferably 0 to 10%. ２ O ３ is a component that forms the network structure of glass. ２ O ３ When it contains Al ２ O ３ The content of Al is preferably 0.5% or more, and more preferably 1% or more. ２ O ３ By ensuring that the content of Al is within the above range, the Young's modulus can be increased. In addition, the weather resistance, moisture resistance, and chemical durability are improved. Furthermore, the average linear expansion coefficient does not become too large, which can suppress thermal cracking of the glass, and chemical strengthening treatment using ion exchange becomes possible. In addition, the Al content in the glass powder is low. ２ O ３ By making the content of Al 10% or less, an increase in viscosity during melting of the glass raw material is suppressed, facilitating glass production, and also improving the formability of vehicle glass, particularly windshields and cover glass for sensors. ２ O ３ The content is more preferably 5% or less, further preferably 3% or less, particularly preferably 2% or less, and most preferably 1.5% or less.

[0039] As described above, the content of heavy metal oxides in the glass powder, i.e., Sb ２ O ３ , PbO, and As ２ O ３ The total content of Sb is preferably 0.005 to 1%.２ O ３ If Sb is contained, it may be reduced during the float process, causing coloration or white haze in the resulting glass. ２ O ３ In addition, there is a correlation with the content of PbO and As in the glass powder. ２ O ３ If the glass powder contains heavy metal oxides, this may cause problems in terms of leaching into the environment and harmfulness to the human body. The content of heavy metal oxides in the glass powder may be 0.01% or more, or may be 0.05% or more. Furthermore, the content of heavy metal oxides in the glass powder may be 0.7% or less, 0.5% or less, or 0.3% or less.

[0040] The glass powder is the above-mentioned SiO ２ , Na ２ O, MgO, CaO, Al ２ O ３ and heavy metal oxides (hereinafter also referred to as "other components"). When other components are contained, the total content thereof is preferably 5% or less.

[0041] For example, glass powder contains K as another component. ２ It may contain O. ２ O is a component that improves the melting property of the glass raw material. ２ When O is contained, K ２ The O content is preferably 0.01% or more, more preferably 0.05% or more, and even more preferably 0.1% or more. ２ If the content of O is too high, the average linear expansion coefficient becomes too large, and the glass becomes prone to thermal cracking. ２ The O content is preferably 5% or less, more preferably 1% or less, further preferably 0.5% or less, and particularly preferably 0.2% or less.

[0042] For example, glass powder contains SO as another component. ３ SO ３ is a component that functions as a fining agent, but most of it is usually converted into SO in the glass manufacturing process.２ and O ２ The glass powder decomposes into SO ３ When containing SO ３ The content of SO in the glass powder is preferably 0.01% or more, more preferably 0.05% or more, further preferably 0.1% or more, and particularly preferably 0.2% or more. ３ The content of is preferably 1% or less, more preferably 0.5% or less, and even more preferably 0.4% or less, from the viewpoint of suppressing deterioration in quality due to an increase in white foam, i.e., sulfate defects.

[0043] For example, the glass powder may contain Fe as another component. ２ O ３ It may contain Fe ２ O ３ The Fe contained in the glass can provide heat insulation properties. ２ O ３ The content of FeO, which is an oxide of divalent iron, and Fe, which is an oxide of trivalent iron ２ O ３ Total iron content (Fe ２ O ３ The glass powder contains Fe ２ O ３ When containing Fe ２ O ３ The content of Fe in the glass powder is preferably 0.005% or more, and more preferably 0.008% or more. ２ O ３ From the viewpoint of increasing the transmittance of the glass, the content is more preferably 2% or less, further preferably 0.05% or less, and particularly preferably 0.02% or less.

[0044] Other components include, for example, Li ２ O, B ２ O ３ , ZnO, SrO, BaO, ZrO ２ , Y ２ O ３ , TiO ２ , CeO ２ , Nd ２ O ５ , GaO ２ , GeO２ , MnO ２ , NiO, Cr ２ O ３ , V ２ O ５ , Er ２ O ３ , Au ２ O ３ , Ag ２ O, CuO, CdO, MoO ３ , Cl, F, SnO ２ These may be metal ions or oxides. Other components may be contained for various purposes (for example, fining and coloring).

[0045] (Reducing Agent) The reducing agent of this embodiment is Sb ２ O ３ , PbO, and As ２ O ３The reducing agent may be any suitable compound capable of reducing at least one heavy metal oxide selected from the group consisting of (a) and (b) and soluble in the liquid medium described below. The reducing agent of this embodiment is preferably a water-soluble organic compound, as it dissolves in water, a preferred liquid medium. Organic compounds with a boiling point of 250°C or higher are particularly preferred, as they function appropriately as reducing agents even when heated at temperatures of 700°C or higher or 1000°C or higher. Examples of water-soluble organic compounds include sugars, glycols, hydroxy acids, amino acids, carboxylic acids, esters, proteins, gelatin, and polymers (such as polyvinyl alcohol, polyamide, polyethylene oxide, polyacrylic acid, polyacrylamide, and polyethyleneimine). Among these, sugars are preferred due to their high solubility in water. Sugars are classified into monosaccharides, disaccharides, and polysaccharides. Examples of monosaccharides include glucose and fructose. Examples of disaccharides include sucrose, lactose, maltose, trehalose, and sucralose, with sucrose (cane sugar) being preferred due to its easy availability. Examples of polysaccharides include starch, glycogen, agarose, pectin, and gums. Note that sucralose contains Cl, which can assist in the role of the halogenating agent described below. An organic solvent may also be used as the liquid medium. Examples of organic solvents include ether-based solvents, alcohol-based solvents, ester-based solvents, ketone-based solvents, and other hydrocarbon-based solvents. Resins are preferred as reducing agents that dissolve in the organic solvent liquid medium. Examples of resins include cellulose, acrylic, polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), polyamide (PA), polycarbonate (PC), butyral, melamine, rosin, silicone, polyester, and epoxy.

[0046] The reducing agent in this embodiment may be used as a reducing agent solution in a state where it is dissolved in a liquid medium from the beginning to obtain the mixture of this embodiment, or the mixture of this embodiment may be obtained by mixing a powdered reducing agent with a liquid medium together with other components such as a halogenating agent. Alternatively, the reducing agent may be dissolved in a liquid medium used as an auxiliary agent when crushing glass. The reducing agent solution refers to a liquid in which the above-mentioned reducing agent is dissolved in a liquid medium.

[0047] In the mixture of this embodiment in the first and second manufacturing methods, the content of the reducing agent dissolved in the liquid medium per 100 parts by mass of glass powder is typically 1 to 30 parts by mass, preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass, from the viewpoint of sufficiently reducing the heavy metal oxide of this embodiment and not leaving much residue of the reducing agent after heating. Here, the content may be 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and may be 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. When a reducing agent solution is used, the product of the content of the reducing agent solution per 100 parts by mass of glass powder and the weight concentration of the reducing agent in the reducing agent solution is adjusted to fall within the above range. In the mixture of the third manufacturing method, the content of the reducing agent dissolved in the liquid medium per 100 parts by mass of glass powder is the same as above.

[0048] (Halogenating Agent) In the first and second production methods, the mixture of the present embodiment preferably contains a halogenating agent. In the third production method, the dried product and a halogenated agent are mixed after the step of obtaining a dried product described below and before the heating step.

[0049] The halogenating agent is Sb in the glass powder. ２ O ３ , PbO, and As ２ O ３Although there are no particular limitations on the halogen-containing organic polymer compounds as long as they can convert at least one heavy metal oxide selected from the above into a halide, halogen-containing organic polymer compounds and halogen-containing inorganic compounds are preferred from the viewpoint of availability and the like. The halogen-containing organic polymer compounds are organic polymer compounds containing halogen atoms, and examples thereof include polyvinylidene chloride and polyvinyl chloride. Note that the halogen-containing organic polymer compounds contain C, and therefore can assist in the role of the reducing agent described above. Examples of halogen-containing inorganic compounds include CaCl ２ , CaCl ２ ・2H ２ O, CaCl ２ ・4H ２ O, CaCl ２ ・6H ２ O, CaBr ２ , CaBr ２ ・2H ２ O, CaBr ２ ・4H ２ O, CaBr ２ ・6H ２ O, CaF ２ , KCl, NaCl, NaF, MgCl ２ , MgCl ２ ・6H ２ O, N.H. ４ Among them, from the viewpoint of cost and halogen content, CaCl ２ , CaCl ２ ・2H ２ O and NaCl are particularly preferred.

[0050] The halogenating agent may be in powder form, or a halogenating agent solution in which the halogenating agent is dissolved in a liquid medium may be used. Examples of the halogenating agent solution include an aqueous halogenating agent solution using water as the liquid medium. In the first and second production methods, the liquid medium for dissolving the halogenating agent may also function as the liquid medium for dissolving the reducing agent in the mixture of this embodiment.

[0051] In the first and second manufacturing methods, when a halogenating agent is contained in the mixture of the present embodiment, the content of the halogenating agent relative to 100 parts by mass of the glass powder is typically 1 to 30 parts by mass, preferably 2 to 20 parts by mass, and more preferably 3 to 15 parts by mass, from the viewpoint of sufficiently halogenating the heavy metal oxide of the present embodiment and ensuring that the amount of volatilized halogen-containing gas is within an appropriate range. Here, the content may be 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and may be 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. When a halogenating agent solution is used, the product of the content of the halogenating agent solution relative to 100 parts by mass of the glass powder and the weight concentration of the halogenating agent in the halogenating agent solution is adjusted to fall within the above-mentioned range. In addition, in the third manufacturing method, the amount of halogenating agent added to be mixed with the dried material described later relative to 100 parts by mass of glass powder is the same as the range of the content of the halogenating agent relative to 100 parts by mass of glass powder in the mixture of this embodiment in the first and second manufacturing methods described above.

[0052] (Liquid Medium) The liquid medium is not particularly limited as long as it dissolves the reducing agent in the mixture of the present embodiment. Examples include water and organic solvents (ethanol, isopropyl alcohol, etc.), and among these, water is preferred from the viewpoint of safety.

[0053] In the mixture of this embodiment in the first and second manufacturing methods, the content of the liquid medium per 100 parts by mass of the glass powder is typically 1 to 50 parts by mass, preferably 3 to 30 parts by mass, and more preferably 5 to 20 parts by mass, from the viewpoint of sufficiently reducing the heavy metal oxide of this embodiment and keeping steam generation within a certain range. Here, the content may be 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and may be 50 parts by mass or less, preferably 30 parts by mass or less, and more preferably 20 parts by mass or less. The content of the liquid medium per 100 parts by mass of the glass powder in the mixture in the third manufacturing method is the same as above.

[0054] In the mixture of this embodiment, the reducing agent is dissolved in the liquid medium. The liquid medium may be any liquid medium capable of dissolving the reducing agent and contained in the mixture of this embodiment. For example, it may be a liquid medium derived from the reducing agent solution described above, a liquid medium derived from a halogenating agent solution containing a halogenating agent, a liquid medium derived from a solution containing other components contained in the mixture of this embodiment, a liquid medium used as an aid in crushing glass, or other liquid mediums. Note that if the liquid medium is derived from a solution containing components other than the reducing agent, depending on the amount and mixing method, the reducing agent may not be dissolved in the mixture of this embodiment. Therefore, the liquid medium is preferably a liquid medium derived from a reducing agent solution.

[0055] In the manufacturing method of this embodiment, it is important that the reducing agent is dissolved in the liquid medium in the mixture of this embodiment. As described above, dissolving the reducing agent in the liquid medium in the mixture of this embodiment allows the reducing agent to be present approximately uniformly over the entire surface of the glass powder. This allows the heavy metal oxides contained in the glass powder to react with the reducing agent efficiently in the heating step described below, producing heavy metal fine particles. The heavy metals are then vaporized by heating, or the heavy metals become heavy metal oxides and then vaporize. Furthermore, if a halogenating agent is present, the heavy metal oxides react with the halogenating agent in the presence of the reducing agent, causing the halogenated heavy metals to vaporize upon heating. These reactions are believed to reduce the amount of heavy metal oxides originating from the glass powder in the resulting glass. While grinding the glass together with the reducing agent without using a liquid medium can disperse the reducing agent to some extent on the surface of the glass powder, this is insufficient in terms of uniformity.

[0056] The method for obtaining the mixture of the present embodiment in the first and second production methods is not particularly limited, but examples thereof include the following methods (1) and (2): (1) Sb ２ O ３ , PbO, and As ２ O３ The mixture of the present embodiment is obtained by mixing a glass powder containing at least one heavy metal oxide selected from the group consisting of Sb, Sb, Sb(II), Sb(III ... ２ O ３ , PbO, and As ２ O ３ A glass material containing at least one heavy metal oxide selected from the group consisting of: a reducing agent solution; and optionally a halogenating agent. The glass material is then pulverized to form a glass powder, thereby obtaining the mixture of the present embodiment.

[0057] The method for obtaining the mixture in the third production method is not particularly limited, but examples thereof include the following methods (3) and (4). (3) Sb ２ O ３ , PbO, and As ２ O ３ (4) A glass powder containing at least one heavy metal oxide selected from the group consisting of Sb, Sb-1, Sb-2, Sb-3, Sb-4, Sb-5, Sb-6, Sb-7, Sb-8, Sb-9, Sb-10, Sb-11, Sb-12, Sb-13, Sb-14, Sb-15, Sb-16, Sb-17, Sb-18, Sb-19, ２ O ３ , PbO, and As ２ O ３ A glass material containing at least one heavy metal oxide selected from the group consisting of: and a reducing agent solution are mixed together, and then the glass material is pulverized to form glass powder, thereby obtaining a mixture.

[0058] In the method (1), the glass powder containing the heavy metal oxide is mixed with a reducing agent solution, and optionally with the halogenating agent. In the method (3), the glass powder containing the heavy metal oxide is mixed with a reducing agent solution. The mixing method is not particularly limited, and examples thereof include stirring by vibration or a screw, or spraying the reducing agent solution onto the glass powder by showering.

[0059] Unlike the method (1), the method (2) involves mixing the glass material containing the heavy metal oxide before crushing with the reducing agent solution described above and, optionally, the halogenating agent described above, and then crushing the glass material to obtain a mixture containing glass powder.The method (4) also involves mixing the glass material containing the heavy metal oxide before crushing with the reducing agent solution described above, and then crushing the glass material to obtain a mixture containing glass powder.

[0060] Examples of the glass material include glass cullet, glass plate, glass bottle, etc. The mixing method and pulverizing method are not particularly limited, and include methods using a ball mill, a disk mill, a vibration mill, a jet mill, etc.

[0061] In addition to the above methods (1) to (4), instead of using a reducing agent solution as described above, the mixture of this embodiment may be obtained by mixing a powdered reducing agent with other components in a liquid medium. Furthermore, the glass powder and glass material preferably comprise glass at least 90% by weight, but may contain (or be attached to) resins, metals, films, etc. These may be mixed in, particularly when utilizing waste materials such as PV cullet. Resins and metals assist the role of the reducing agent during heating. Examples of the resins include ethylene vinyl acetate copolymer (EVA) and polyvinyl butyral (PVB), and examples of the metals include Al, Si, Cu, and Fe.

[0062] In addition to the reducing agent that dissolves in the liquid medium, the mixture of this embodiment may contain at least one of a metal powder, a water-insoluble organic powder, and a carbon powder (collectively referred to as a "non-soluble powder") that is insoluble in the liquid medium as a reduction promoter. The inclusion of the non-soluble powder in the mixture of this embodiment further promotes the reduction of heavy metal oxides, thereby facilitating the subsequent vaporization of the heavy metals. The metal powder is preferably a metal powder containing at least one element selected from Al, Si, Cu, and Fe. The water-insoluble organic powder is preferably a polymeric organic material, and particularly preferably a resin such as EVA, PVB, or silicone.

[0063] When the mixture of this embodiment contains the undissolved powder, the content of the undissolved powder in the mixture of this embodiment is typically 0.1 to 20 parts by mass, preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass, relative to 100 parts by mass of glass powder, from the viewpoint of appropriately controlling the composition of the glass obtained by the production method of this embodiment and from the viewpoint of sufficiently reducing the heavy metal oxide of this embodiment. Here, the content may be 0.1 parts by mass or more, preferably 1 part by mass or more, and more preferably 2 parts by mass or more, and may be 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less.

[0064] The non-dissolvable powder may be contained in the mixture of this embodiment before the heating step described below. The non-dissolvable powder may be contained in the mixture, for example, by mixing the non-dissolvable powder with other components in steps (1) to (4) to obtain the mixture of this embodiment, or by adding the non-dissolvable powder to the mixture obtained by steps (1) to (4), or by other methods.

[0065] In addition to the glass powder, the mixture of this embodiment may contain glass raw materials for the purpose of adjusting the composition of the resulting glass. In the manufacturing method of this embodiment, the halogenating agent is optionally added. However, when a halogenating agent is added, the composition of the resulting glass may be biased depending on the type of halogenating agent. By adding a glass raw material, the bias in the glass composition can be adjusted. Note that the term "glass raw material" as used herein is to be distinguished from "glass powder," "glass material," and "glass" obtained by the manufacturing method of this embodiment. As the glass raw material, conventionally known glass raw materials such as oxides, carbonates, nitrates, and sulfates can be appropriately used depending on the composition of the glass to be obtained. Furthermore, fining agents such as sulfates are also included in the glass raw materials.

[0066] When the mixture of this embodiment contains the glass frits, the content of the glass frits in the mixture of this embodiment relative to 100 parts by mass of the glass powder is usually 0.1 to 50 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 10 parts by mass, from the viewpoint of appropriately adjusting the glass composition obtained by the production method of this embodiment. Here, the content may be 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, and may be 50 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

[0067] <Drying Step> In the second manufacturing method, before heating the mixture of the present embodiment, the mixture is dried to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent (hereinafter also referred to as the dried product of the present embodiment) (Step S022). In the above step, if the mixture contains a halogenating agent, the dried product also contains the halogenating agent or a halogen component derived therefrom (Step S22). In the third manufacturing method, Sb ２ O ３ , PbO, and As ２ O ３ The method includes a process for drying a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of ...

[0068] In the second manufacturing method, the dried product of the present embodiment containing a glass powder containing a heavy metal oxide, a reducing agent, and optionally a halogenating agent is obtained by the drying step. In the third manufacturing method, the dried product containing a glass powder containing a heavy metal oxide and a reducing agent is obtained by the drying step.

[0069] In the second manufacturing method of this embodiment, the content of the glass powder relative to the entire dried product is typically 60 to 99 mass%, preferably 75 to 98 mass%, and more preferably 85 to 97 mass%, from the viewpoint of efficiently promoting the reaction between the glass powder and the reducing agent and optional halogenating agent, and from the viewpoint of appropriately controlling the glass composition. Here, the content may be 60 mass% or more, preferably 75 mass% or more, more preferably 85 mass% or more, and may be 99 mass% or less, preferably 98 mass% or less, and more preferably 97 mass% or less. In the third manufacturing method, the content of the glass powder relative to the entire dried product is the same as above.

[0070] In the dried product of this embodiment in the second manufacturing method, the content of the reducing agent per 100 parts by mass of the glass powder is typically 1 to 30 parts by mass, preferably 2 to 20 parts by mass, and more preferably 3 to 15 parts by mass, from the viewpoint of sufficiently reducing heavy metal oxides and not leaving much residue of the reducing agent after heating. Here, the content may be 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and may be 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. The content of the reducing agent per 100 parts by mass of the glass powder in the dried product in the third manufacturing method is also the same as above.

[0071] When the dried product of this embodiment in the second manufacturing method contains a halogenating agent, the content of the halogenating agent in the dried product relative to 100 parts by mass of the glass powder is typically 1 to 30 parts by mass, preferably 2 to 20 parts by mass, and more preferably 3 to 15 parts by mass, from the viewpoint of sufficiently halogenating the heavy metal oxide of this embodiment and ensuring that the amount of volatilized halogen-containing gas is within an appropriate range. Here, the content may be 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and may be 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. Furthermore, in the third manufacturing method, the amount of halogenating agent added relative to 100 parts by mass of the glass powder is also in the same range as the content of the halogenating agent relative to 100 parts by mass of the glass powder in the dried product of this embodiment in the second manufacturing method described above.

[0072] The dried product of this embodiment may also contain a glass raw material or an insoluble powder as a reduction promoter that does not dissolve in the liquid medium, as in the mixture of this embodiment.

[0073] When the dried product of the present embodiment in the second manufacturing method contains the undissolved powder, the content of the undissolved powder in the dried product of the present embodiment relative to 100 parts by mass of glass powder is typically 0.1 to 20 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 15 parts by mass, from the viewpoint of appropriately controlling the composition of the glass obtained by the manufacturing method of the present embodiment and from the viewpoint of sufficiently reducing the heavy metal oxide of the present embodiment. Here, the content may be 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, and may be 20 parts by mass or less, or 15 parts by mass or less. The same applies to the dried product in the third manufacturing method.

[0074] When the dried product of the present embodiment in the second manufacturing method contains the glass frit, the content of the glass frit relative to 100 parts by mass of the glass powder in the dried product of the present embodiment is usually 0.1 to 50 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 10 parts by mass, from the viewpoint of appropriately adjusting the glass composition obtained by the manufacturing method of the present embodiment. Here, the content may be 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and may be 50 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. The same applies to the dried product in the third manufacturing method.

[0075] In addition, the dried product of this embodiment is Sb ２ O ３ , PbO, and As ２ O ３The present invention relates to a dried product comprising a glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder containing a heavy metal oxide, a reducing agent, an optional halogenating agent, and a liquid medium, the reducing agent being dissolved in the liquid medium, and the dried product is obtained by drying the mixture. As described above, the dried product is obtained by drying the mixture in which the reducing agent is dissolved in the liquid medium, and therefore the reducing agent is believed to be substantially uniformly present over the entire surface of the glass powder. Identifying the dried product of this embodiment in which the reducing agent is present in the glass powder by structure requires analysis by Raman spectroscopy or the like over the entire surface of the glass powder, which requires a significant amount of time. Furthermore, the density of the reducing agent on the surface of the glass powder is extremely low, and therefore likely to be below the detection limit. Therefore, due to circumstances that make it impossible and even impractical to directly identify the dried product of this embodiment by structure ("impossible / impractical circumstances"), the dried product of this embodiment is appropriately identified as a "product" by the definition of "a dried product obtained by drying a mixture." The dried product of this embodiment may contain a small amount of water due to insufficient drying. In this case, the water content is, for example, 3% by mass or less. The dried product of this embodiment may also contain water of crystallization from the halogenating agent.

[0076] <Heating Step> In the first manufacturing method, the mixture obtained in step S011 is heated at a temperature of 700° C. or higher (steps S012, S023, and S033). In the second manufacturing method, the dried product obtained in step S022 is heated at a temperature of 700° C. or higher (steps S012, S023, and S033). In the third manufacturing method, the dried product obtained in step S032 is heated at a temperature of 1000° C. or higher (steps S12, S23, and S33).

[0077] This heating process causes the heavy metal oxides contained in the glass powder to react with the reducing agent, which is uniformly distributed over the entire surface of the glass powder, to produce heavy metal particles. The heavy metals are then vaporized by heating, or vaporized after becoming heavy metal oxides. Furthermore, if a halogenating agent is present, the halogenated heavy metals are vaporized by heating. This is thought to reduce the amount of heavy metal oxides in the resulting glass.

[0078] The heating temperature is 700°C or higher from the viewpoint of efficiently promoting the reaction between the glass powder and the reducing agent or halogenating agent, preferably 900°C or higher, more preferably 1000°C or higher, even more preferably 1050°C or higher, even more preferably 1100°C or higher, and particularly preferably 1200°C or higher. Furthermore, from the viewpoint of energy saving and protecting the heating device, the heating temperature may be 1400°C or lower. The atmosphere during heating preferably contains water vapor, and the dew-point temperature is preferably 0°C or higher. In particular, the atmosphere during heating preferably contains water vapor and has a dew-point temperature of 0°C or higher. This promotes the vaporization of heavy metals. The dew-point temperature is more preferably 40°C or higher, even more preferably 55°C or higher, and particularly preferably 70°C or higher. Superheated steam may also be used.

[0079] Furthermore, the atmosphere during heating preferably contains 30% by mass or less of oxygen among components other than water vapor. This promotes the reaction between the heavy metal oxides contained in the glass powder and the reducing agent, thereby promoting the vaporization of the heavy metals. The atmosphere during heating preferably contains 15% by mass or less of oxygen among components other than water vapor, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less. It may also be 0% by mass, i.e., no oxygen. The atmosphere during heating preferably contains 70% by mass or more of an inert gas among components other than water vapor. That is, when the entire atmosphere during heating is assumed to be 100% by mass in a state where there is no water vapor, it preferably contains 70% by mass or more of an inert gas. This promotes the reaction between the heavy metal oxides contained in the glass powder and the reducing agent, thereby promoting the vaporization of the heavy metals. The atmosphere during heating preferably contains 85% by mass or more of an inert gas, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, particularly preferably 99% by mass or more, and may even be 100% by mass. Examples of the inert gas include nitrogen, argon, helium, neon, and xenon. One or more of these may be used. When two or more types are used, it is preferable that the total of these gases satisfies the above range. For example, when nitrogen gas is used as the inert gas, the atmosphere during heating preferably contains 70% by mass or more of nitrogen, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, particularly preferably 99% by mass or more, and may even be 100% by mass.

[0080] It is more preferable that the atmosphere during the heating contains water vapor, and that the oxygen content of the components other than the water vapor is 30 mass % or less and the dew point temperature is 0°C or higher.

[0081] The heating step may be performed in one stage or in two or more stages. When the heating step is performed in two or more stages, the dew point temperature, nitrogen concentration, and oxygen concentration in the atmosphere during heating may or may not be changed for each stage.

[0082] The glass obtained when the heating step is carried out in one stage may be in a state in which a fired glass product obtained by firing glass powder and a residue obtained by heating the reducing agent and the like are mixed (hereinafter also referred to as a fired glass product).

[0083] Furthermore, when the heating process is performed in two stages, a glass sintered product in which heavy metals have been vaporized is obtained in the first heating stage, and then the glass sintered product obtained in the second heating stage is heated at a higher temperature than in the first heating stage to obtain a glass (hereinafter also referred to as a glass melt) in which the mixture of this embodiment, the dried product, or a mixture of the dried product and a halogenating agent is melted. In other words, the above-mentioned firing (first stage) and melting (second stage) are performed consecutively, and the fired product of the reducing agent, etc. obtained in the first heating stage is melted in the second heating stage. Therefore, the glass obtained is a glass sintered product that does not contain the fired product of the reducing agent, etc. The first heating stage may be performed, for example, at 700°C to 1400°C for 0.01 to 10 hours, followed by a second heating stage at 1400°C to 1700°C for 0.01 to 100 hours. However, if the first heating stage is performed at 1400°C, the second heating stage is performed at a temperature above 1400°C. The second heating step may be carried out in a general glass melting furnace. When a halogenating agent is used in the first or second production method, or when the third production method is adopted, the halogenated heavy metals may be recovered using a scrubber. In particular, a wet scrubber can be used to dissolve the halogenated heavy metals in water, and after a process of separating and purifying the heavy metals from the aqueous solution, the heavy metals can be utilized for other purposes.

[0084] Thus, the obtained glass may be a glass (fired glass product) in a state in which a fired glass product obtained by firing the glass powder by the heating is mixed with residues of the reducing agent, etc., or a glass (molten glass) in a state in which no residues of the reducing agent, etc. are contained. Usually, when heated at a temperature above 1400°C, the latter type of molten glass is obtained.

[0085] The resulting glass has a content of SiO in mass % based on oxides. ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0-10%, heavy metal oxides: 0-0.15% (the content of heavy metal oxides is Sb ２ O ３ , PbO, and As ２ O ３ and halogen elements: 0 to 3% (the halogen element content means the total amount of F, Cl, and Br). The preferred ranges of the content of each component in the resulting glass are the same as the preferred ranges of the content of each component in the glass powder described above, except for the heavy metal oxides and halogen elements.

[0086] The content of the heavy metal oxide of this embodiment in the obtained glass, i.e., Sb ２ O ３ , PbO, and As ２ O ３The total content of these is preferably 0 to 0.15%. As described above, according to the first and second manufacturing methods, the amount of heavy metal oxides originating from the glass powder is reduced in the resulting glass. The content of the heavy metal oxides of this embodiment in the resulting glass is more preferably 0.1% or less, even more preferably 0.05% or less, and particularly preferably 0.02% or less. However, it is not limited to the above range, and it is sufficient that the content of heavy metal oxides in the resulting glass is reduced relative to the content of heavy metal oxides in the glass powder. The ratio of the content of heavy metal oxides in the glass obtained after treatment to the content of heavy metal oxides in the glass powder before treatment, i.e., the rate of change in the total amount of heavy metal oxides, is preferably 0.8 or less, more preferably 0.5 or less, even more preferably 0.3 or less, and particularly preferably 0.1 or less.

[0087] The content of halogen elements in the resulting glass, i.e., the total content of F, Cl, and Br, is preferably 0 to 3%. The halogen elements in the resulting glass are due to the halogenating agent, and by keeping the content at 3% or less, the occurrence of bubble defects in the glass can be suppressed. The content of halogen elements in the resulting glass is more preferably 1% or less, even more preferably 0.5% or less, and particularly preferably 0.1% or less. Alternatively, the content may be 0.005% or more, 0.02% or more, or 0.05% or more.

[0088] When the heating step is performed in two stages, that is, when a glass fired product is obtained in the first stage of heating and then a glass melt is obtained in the subsequent second stage of heating, glass raw materials can be added separately to the glass fired product as necessary at any timing before the second stage of heating in order to adjust the composition of the glass to be obtained. The glass raw materials to be added can be the same as the glass raw materials described in the first and second production methods described above.

[0089] The resulting glass has a content of SiO in mass % based on oxides. ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３: 0-10%, heavy metal oxides: 0.001-0.15% (the content of heavy metal oxides is Sb ２ O ３ , PbO, and As ２ O ３ The glass may contain 0.005 to 3% of halogen elements (the halogen element content means the total amount of F, Cl, and Br). The preferred ranges of the content of each component in the resulting glass are the same as the preferred ranges of the content of each component in the glass powder described above, except for the heavy metal oxides and halogen elements.

[0090] The content of the heavy metal oxide of this embodiment in the obtained glass, i.e., Sb ２ O ３ , PbO, and As ２ O ３ The total content of Sb is preferably 0.001 to 0.15%. ２ O ３ Since it acts as a glass fining agent and also improves the transmittance of the glass, it is preferably contained in an amount of 0.001% or more. As described above, according to the first and second production methods, the amount of heavy metal oxides originating from the above-mentioned glass powder is reduced in the resulting glass. The content of the heavy metal oxide of this embodiment in the resulting glass is more preferably 0.1% or less, even more preferably 0.05% or less, and particularly preferably 0.02% or less. Furthermore, the content may be 0.002% or more, or even 0.005% or more. The value obtained by dividing the content of the heavy metal oxide of this embodiment in the resulting glass by the content of heavy metal oxide in the glass powder before the heat treatment is preferably 0.7 or less, more preferably 0.4 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less. However, the content of heavy metal oxide and the ratio before and after the heat treatment are not limited to the above ranges, as long as the content of heavy metal oxide in the resulting glass is reduced relative to the content of heavy metal oxide in the glass powder.

[0091] The halogen content in the resulting glass, i.e., the total content of F, Cl, and Br, is preferably 0.005 to 3%. The halogen content in the resulting glass is due to the halogenating agent, and by keeping it at 3% or less, the occurrence of bubble defects in the glass can be suppressed. The halogen content in the resulting glass is more preferably 1% or less, even more preferably 0.5% or less, and particularly preferably 0.1% or less. It may also be 0.02% or more, or 0.05% or more.

[0092] The resulting glass is Sb ２ O ３ When the glass contains Sb, the Sb present in the glass ３＋ and Sb ５＋ The content ratio (molar concentration) of [Sb ３＋ ] and [Sb ５＋ ], [Sb ３＋ ] / ([Sb ３＋ ]+[Sb ５＋ The Sb-Redox value represented by [Sb ３＋ ], [Sb ５＋ ] are the Sb in the glass, respectively. ３＋ , Sb ５＋ The molar concentration of [Sb ３＋ ], ([Sb ３＋ ]+[Sb ５＋ ]) can be measured by ICP mass spectrometry.

[0093] When the mixture of this embodiment, the dried product of this embodiment, or a mixture of the dried product and a halogenating agent is heated in two stages, the glass melt obtained in the second stage may be formed into a plate glass. The plate glass can be formed by a conventionally known method, for example, a float method, a press method, a fusion method, and a down-draw method. In particular, when producing a large glass plate, the float method is preferred. Furthermore, continuous forming methods other than the float method, such as a fusion method and a down-draw method, are also preferred.

[0094] The present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and modifications and improvements can be made as appropriate. In addition, the material, shape, size, number, and location of each component in the above-described embodiments are arbitrary and not limited as long as the present invention can be achieved.

[0095] As described above, the present specification discloses the following: [1] Sb ２ O ３ , PbO, and As ２ O ３ A method for producing glass, comprising: obtaining a mixture containing glass powder containing at least one heavy metal oxide selected from the group consisting of Sb, a reducing agent, and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; and heating the mixture at a temperature of 700°C or higher. ２ O ３ , PbO, and As ２ O ３

[0023] A method for producing glass, comprising: obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent; and heating the dried product at a temperature of 700°C or higher. [3] The method for producing glass according to [1] or [2] above, wherein the mixture also contains a halogenating agent. [4] The method for producing glass according to any one of [1] to [3] above, wherein the heating temperature is 1000°C or higher. [5] Sb ２ O ３ , PbO, and As ２ O ３A method for producing glass, comprising: obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent; mixing the dried product with a halogenating agent and heating the mixture at a temperature of 700°C or higher. [6] The method for producing glass according to the above item [5], wherein the heating temperature is 1000°C or higher. [7] The method for producing glass according to any one of the above items [1] to [6], wherein the atmosphere during the heating contains water vapor and has a dew point temperature of 0°C or higher. [8] The method for producing glass according to any one of the above items [1] to [6], wherein the atmosphere during the heating contains 30 mass% or less of oxygen among components other than water vapor. [9] The method for producing glass according to any one of the above [1] to [6], wherein the atmosphere during heating contains water vapor, and among components other than the water vapor, the content of oxygen is 30 mass % or less, and the dew point temperature is 0°C or higher.

[10] The mixture contains Sb ２ O ３ , PbO, and As ２ O ３

[11] The method for producing glass according to any one of the above items [1] to [9], wherein the glass is obtained by mixing a glass powder containing at least one heavy metal oxide selected from the group consisting of Sb and Sb-containing heavy metal oxides with a reducing agent solution. ２ O ３ , PbO, and As ２ O ３

[12] The method for producing glass according to any one of the above items [1] to

[10] , wherein a glass material containing at least one heavy metal oxide selected from the group consisting of Sb, Sb-based ... ２ O ３

[13] A method for producing glass according to any one of the above [1] to

[12] , wherein the reducing agent is a water-soluble organic compound.

[14] A method for producing glass according to any one of the above [1] to

[13] , wherein the liquid medium is water.

[15] A method for producing glass according to any one of the above [1] to

[14] , wherein the reducing agent is a sugar.

[16] A method for producing glass according to any one of the above [1] to

[15] , wherein the median diameter d50 of the glass powder is 100 μm or less.

[17] A method for producing glass according to any one of the above [1] to

[16] , wherein the halogenating agent is a halogen-containing inorganic compound.

[18] The halogenating agent is CaCl ２ , CaCl ２ ・2H ２

[19] The method for producing glass according to any one of [1] to

[18] above, wherein at least one of the mixture and the dried product further contains at least one selected from the group consisting of a metal powder containing at least one element selected from Al, Si, Cu, and Fe, a water-insoluble organic powder, and a carbon powder.

[20] The method for producing glass according to any one of [1] to

[19] above, wherein at least one of the mixture and the dried product further contains a glass raw material.

[21] The glass powder has a content, expressed in mass % on an oxide basis, of SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0 to 10%, and heavy metal oxide: 0.005 to 1%, and the content of the heavy metal oxide satisfies ２ O ３ , PbO, and As ２ O ３

[22] The method for producing glass according to any one of the above [1] to

[20] , wherein the content of the obtained glass expressed in mass % based on oxides is SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al２ O ３ : 0 to 10%, heavy metal oxides: 0 to 0.15%, and halogen elements: 0 to 3%, and the content of the heavy metal oxides is ２ O ３ , PbO, and As ２ O ３ The method for producing glass according to any one of the above [1] to

[21] , wherein the content of the halogen elements means the total amount of F, Cl, and Br.

[0096]

[23] Sb ２ O ３ , PbO, and As ２ O ３

[24] A mixture comprising a glass powder containing at least one heavy metal oxide selected from the group consisting of Sb, a reducing agent, and a liquid medium, wherein the reducing agent is dissolved in the liquid medium.

[25] A dried product obtained by drying the mixture, wherein the mixture contains Sb ２ O ３ , PbO, and As ２ O ３

[26] A dried product comprising a glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder, a reducing agent, and a liquid medium, wherein the reducing agent is dissolved in the liquid medium.

[27] The dried product according to the above

[25] , wherein the mixture further contains a halogenating agent, and the dried product further contains a halogen component derived from the halogenating agent.

[28] A dried product according to the above

[26] , wherein the content, expressed as mass % on an oxide basis, of SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0 to 10%, heavy metal oxides: 0.001 to 0.15%, and halogen elements: 0.005 to 3%, and the content of the heavy metal oxides is ２ O ３ , PbO, and As ２ O ３ The content of the halogen element means the total amount of F, Cl, and Br.

[28] Sb ２ O３ Sb present in the glass ３＋ and Sb ５＋ is the molar concentration of [Sb ３＋ ] and [Sb ５＋ ], [Sb ３＋ ] / ([Sb ３＋ ]+[Sb ５＋ ]) is 80 to 100%.

[0097] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. Examples 1 to 15 and 19 to 28 are working examples, and Examples 16 to 18 are comparative examples.

[0098] Example 1 Preparation of Mixtures A glass material (cullet) having glass composition A (in mass % based on oxides) shown in Table 1 below was pulverized for 3 hours at 200 rpm in a planetary ball mill (using a zirconia pot and balls manufactured by Verder Scientific). The median diameter d50 of the glass powder obtained after pulverization was 5.5 μm. The median diameter d50 of the glass powder was measured using a laser diffraction / scattering particle size distribution analyzer (SALD-2300 manufactured by Shimadzu Corporation) in a wet manner by dispersing the glass powder in water, followed by ultrasonic disintegration of agglomerated powders. The symbol "-" in Tables 1, 2, 6, and 7 indicates that the component was below the detection limit.

[0099]

[0100] 16.6 parts by mass of an aqueous solution of a reducing agent in which 50% by mass of sucrose is dissolved (reducing agent solution) and 50% by mass of CaBr ２ ・2H ２ The glass was then placed in a plastic bag and mixed evenly by hand, then transferred to an alumina crucible and heated at 1100°C for 2 hours in an air atmosphere (76% by mass of nitrogen, 23% by mass of oxygen) with a dew point of 10°C. The glass was crushed in an agate mortar and pressed into a powder, which was analyzed by fluorescent X-ray analysis to determine the presence of Sb. ２ O ３ , PbO, and As ２O ３ The results are shown in Table 3. In Tables 3 to 5, blank cells indicate that the component was not added, and "-" indicates that the component was below the detection limit.

[0101] (Example 2) A glass was produced in the same manner as in Example 1, except that the heating temperature was 1200°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0102] Example 3 A glass was produced in the same manner as in Example 1, except that the amount of the aqueous solution of the halogenating agent added was 8.3 parts by mass. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0103] Example 4: 50% by weight of CaBr ２ ・2H ２ Instead of an aqueous solution of a halogenating agent containing dissolved O, CaBr ２ ・2H ２ A glass was produced in the same manner as in Example 1, except that 8.3 parts by mass of O powder was used. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0104] Example 5: 50% by weight of CaBr ２ ・2H ２ Instead of the aqueous solution of the halogenating agent in which O was dissolved, 32% by weight of CaCl ２ A glass was produced in the same manner as in Example 1, except that 12.2 parts by mass of an aqueous solution of a halogenating agent in which Sb was dissolved was used. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0105] Example 6 A glass was produced in the same manner as in Example 5, except that the heating temperature was 1300°C. ２ O ３, PbO, and As ２ O ３ The results are shown in Table 3.

[0106] (Example 7) Glass (fired glass product and molten glass product) was produced in the same manner as in Example 5, except that heating was performed at 1300°C for 2 hours in an air atmosphere (76% nitrogen, 23% oxygen by mass) with a dew point temperature of 10°C, and then transferred to a platinum crucible, and further heated and melted at 1500°C for 2 hours in an atmosphere of 95% nitrogen and 5% oxygen with a dew point temperature of 50°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3. The total composition of the finally obtained glass (glass melt) was quantified by X-ray fluorescence analysis, and the results are shown in Table 7. The Sb-Redox content of the finally obtained glass (glass melt) was measured by ICP mass spectrometry and was found to be 100%.

[0107] Example 8 A glass was produced in the same manner as in Example 5, except that the amount of the aqueous solution of the halogenating agent added was 5.3 parts by mass. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0108] (Example 9) A glass was produced in the same manner as in Example 1, except that the grinding time of the glass material (cullet) was 1 hour and the median diameter d50 of the glass powder obtained after grinding was 17.3 μm. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0109] (Example 10) A glass was produced in the same manner as in Example 1, except that the grinding time of the glass material (cullet) was 6 hours and the median diameter d50 of the glass powder obtained after grinding was 3.8 μm. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 3.

[0110] (Example 11) A mixture of glass powder, an aqueous solution of a reducing agent, and an aqueous solution of a halogenating agent was dried at 80°C for 3 hours, and then glass was produced in the same manner as in Example 1, except that 8.3 parts by mass of Al (metallic aluminum) powder was further added as an insoluble powder per 100 parts by mass of the glass powder. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0111] Example 12: 50% by weight of CaBr ２ ・2H ２ Instead of an aqueous solution of a halogenating agent containing dissolved O, CaCl ２ ・2H ２ A glass was produced in the same manner as in Example 1, except that 5.2 parts by mass of O powder was used. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0112] Example 13: 50% by weight of CaBr ２ ・2H ２ Glass was produced in the same manner as in Example 1, except that 16.4 parts by mass of an aqueous solution of a halogenating agent in which 25% by mass of NaCl was dissolved was used instead of the aqueous solution of a halogenating agent in which O was dissolved. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0113] Example 14 A glass was produced in the same manner as in Example 5, except that a glass material (cullet) having a glass composition B (expressed as mass % on an oxide basis) shown in Table 2 was used instead of a glass material (cullet) having a glass composition A (expressed as mass % on an oxide basis) shown in Table 1. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0114]

[0115] (Example 15) 24.9 parts by mass of a reducing agent solution (reducing agent solution) containing 50% by mass of sucrose was added to 100 parts by mass of glass material (cullet) having glass composition A (in mass % based on oxides) shown in Table 1, and the mixture was pulverized at 200 rpm for 3 hours using a planetary ball mill (manufactured by Verder Scientific, using a zirconia pot and balls). The median diameter d50 of the glass powder obtained after pulverization was 3.7 μm. The mixture of the obtained glass powder and the reducing agent solution was dried at 80° C. for 15 hours to obtain a dried product, which was then crushed in an agate mortar. CaCl was added to 100 parts by mass of the glass powder in the dried product. ２ The mixture was placed in a plastic bag and mixed evenly by hand, then transferred to an alumina crucible and heated at 1100°C for 2 hours in an air atmosphere (76% by mass of nitrogen, 23% by mass of oxygen) with a dew point of 10°C. The resulting glass was crushed in an agate mortar and pressed into a powder, which was analyzed by fluorescent X-ray analysis to determine the presence of Sb. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0116] Example 16 A glass was produced in the same manner as in Example 1, except that 8.3 parts by mass of sucrose powder was used instead of the reducing agent solution in which 50% by mass of sucrose was dissolved in water. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0117] Example 17: A glass was produced in the same manner as in Example 11, except that the reducing agent solution in which 50% by mass of sucrose was dissolved in water was not added and the drying step was not performed. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0118] Example 18 A glass was produced in the same manner as in Example 17, except that 3.5 parts by mass of C (carbon) powder, which is an insoluble powder serving as a reduction promoter, was added instead of Al powder, which is a metal powder serving as a reduction promoter.２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0119] Example 19 A glass was produced in the same manner as in Example 14, except that the heating was carried out at 1200°C for 2 hours in an air atmosphere (76% by mass of nitrogen, 23% by mass of oxygen) with a dew point temperature of 60°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0120] Example 20 A glass was produced in the same manner as in Example 19, except that the heating was carried out in an atmosphere of 95 mass % nitrogen and 5 mass % oxygen at a dew point temperature of 60°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 4.

[0121] Example 21 A glass was produced in the same manner as in Example 13, except that the heating was carried out at 1200°C for 2 hours in an atmosphere of 95% by mass of nitrogen and 5% by mass of oxygen with a dew point temperature of 60°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0122] Example 22: 32% by weight of CaCl ２ Glass was produced in the same manner as in Example 20, except that the aqueous solution of the halogenating agent containing Sb dissolved therein was not added. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0123] Example 23 A glass was produced in the same manner as in Example 22, except that the heating was carried out at 1000°C for 2 hours in an atmosphere of 95% by mass of nitrogen and 5% by mass of oxygen with a dew point temperature of 60°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0124] Example 24 A glass was produced in the same manner as in Example 22, except that the heating was carried out at 1000°C for 2 hours in an atmosphere of 95% by mass of nitrogen and 5% by mass of oxygen with a dew point temperature of 10°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0125] Example 25 A glass was produced in the same manner as in Example 22, except that the heating was carried out at 900°C for 2 hours in an atmosphere of 98 mass% nitrogen and 2 mass% oxygen with a dew point temperature of 60°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0126] Example 26: 16.6 parts by mass of a reducing agent solution (reducing agent solution) containing 50% by mass of sucrose dissolved in 100 parts by mass of glass material (cullet) having the glass composition C (in mass % based on oxides) shown in Table 6 was added, and the mixture was milled for 3 hours at 200 rpm using a planetary ball mill (manufactured by Verder Scientific, using a zirconia pot and balls). The median diameter d50 of the glass powder obtained after milling was 4.5 μm. The mixture of the obtained glass powder and the reducing agent solution was dried at 80°C for 15 hours to obtain a dried product, which was then crushed in an agate mortar and transferred to an alumina crucible and heated at 1000°C for 2 hours in an atmosphere of 95% by mass nitrogen and 5% by mass oxygen with a dew point of 60°C. The obtained glass was crushed in an agate mortar, pressed into a powder, and subjected to X-ray fluorescence analysis to determine the presence of Sb. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0127] Example 27 A glass was produced in the same manner as in Example 22, except that a glass material (cullet) having glass composition C (expressed as mass % on an oxide basis) shown in Table 6 was used instead of a glass material (cullet) having glass composition A (expressed as mass % on an oxide basis) shown in Table 1, and heating was performed at 800°C for 0.4 hours in an atmosphere of 100 mass % nitrogen and 0 mass % oxygen at a dew point temperature of -40°C.２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0128] Example 28: A glass was produced in the same manner as in Example 27, except that the mixture of the glass powder and the aqueous solution of the reducing agent was dried at 80°C for 3 hours and heated at 1000°C for 0.4 hours in an atmosphere of 100% by mass of nitrogen and 0% by mass of oxygen with a dew point temperature of -40°C. ２ O ３ , PbO, and As ２ O ３ The results are shown in Table 5.

[0129]

[0130]

[0131]

[0132]

[0133]

[0134] According to the results in Tables 3 to 5, the heavy metal oxide content in the resulting glass was reduced to 0.15% by mass or less by heating the mixtures (Examples 1 to 10, 12 to 14, 19 to 25, and 27) containing a glass powder containing a heavy metal oxide, a reducing agent, and water as a liquid medium, in which the reducing agent was dissolved in the water, or the dried products thereof (Examples 11, 26, and 28), or the mixtures (Example 15) containing a glass powder containing a heavy metal oxide, a reducing agent, and water as a liquid medium, in which the reducing agent was dissolved in the water, at 700° C. or higher. Furthermore, in Examples 4, 12, and 15, although a powder was used as the halogenating agent, good results were obtained, similar to those obtained when an aqueous solution was used as the halogenating agent (Examples 1 to 3, 5 to 11, 13, 14, and 19 to 21). This is thought to be because halogenating agents are easily dissolved in glass regardless of their form, or because halogenating agents act as halogen gases when heated, so the form they are added in is irrelevant. Furthermore, in the glass (fired glass, molten glass) obtained by the two-stage heating in Example 7, the content of heavy metal oxides was also kept low at 0.15 mass% or less, and the rate of change in the total amount of heavy metal oxides was also kept at 0.7 or less. Furthermore, ZrO, which is not contained in the glass material (cullet) used, ２ The detected CaO content is due to the equipment used during grinding (a zirconia pot and balls). The increased CaO content is due to the halogenating agent (CaCl ２ ) Furthermore, in Examples 19 to 23, 25, and 26, the dew point temperature in the atmosphere during heating was increased to 60°C, which enabled the heavy metal oxide content in the resulting glass to be kept low. Furthermore, in Examples 20 to 28, the oxygen concentration in the atmosphere during heating was reduced to 5 mass% or less, which enabled the heavy metal oxide content in the resulting glass to be kept low. This is thought to be because the evaporation of halogenated heavy metals was promoted by reducing the oxygen concentration in the atmosphere during heating.

[0135] On the other hand, in Examples 16, 17, and 18, a powder was used as the reducing agent or reduction assistant, and the reducing agent or reduction assistant was not dissolved in the liquid medium in the mixture. Therefore, the heavy metal oxide Sb in the glass obtained after heating was not dissolved. ２ O ３ The contents of the reducing agent or reduction assistant were high, at 0.161 mass%, 0.167 mass%, and 0.166 mass%, respectively. This is thought to be because the reducing agent or reduction assistant was not dissolved in the liquid medium in the mixture, and therefore the reducing agent or reduction assistant was not present substantially uniformly over the entire surface of the glass powder, and therefore the heavy metal oxide contained in the glass powder and the reducing agent or reduction assistant did not react efficiently during the heating process. Note that the mixture of Example 16 used an aqueous solution as the halogenating agent, and the reducing agent was water-soluble. However, the aqueous solution dispersed throughout the mixture was dilute relative to the reducing agent powder, so the reducing agent did not dissolve in the liquid medium in the mixture. The mixtures of Examples 17 and 18 used an aqueous solution as the halogenating agent, but the reducing assistant was not water-soluble, so the reducing assistant did not dissolve in the liquid medium in the mixture.

[0136] Furthermore, a halogenating agent is not essential for the mixture or dried product, and even if a mixture or dried product not containing a halogenating agent is used, by using a mixture in which a reducing agent is dissolved in a liquid medium or a dried product thereof and heating at a temperature of 700°C or higher, the heavy metal oxide content in the obtained glass can be kept low to 0.15 mass% or less, and the rate of change in the total heavy metal oxide content can be kept to 0.7% or less (Examples 22 to 28).

[0137] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on September 8, 2023 (Patent Application No. 2023-146355) and November 30, 2023 (Patent Application No. 2023-202908), the contents of which are incorporated herein by reference.

Claims

1. Sb ２ O ３ , PbO, and As ２ O ３ obtaining a mixture containing glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder, a reducing agent, and a liquid medium, the reducing agent being dissolved in the liquid medium; and heating the mixture at a temperature of 700° C. or higher.

2. Sb ２ O ３ , PbO, and As ２ O ３ obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent; and heating the dried product at a temperature of 700° C. or higher.

3. The method for producing glass according to claim 1 or 2, wherein the mixture contains a halogenating agent.

4. The method for producing glass according to claim 3, wherein the heating temperature is 1000° C. or higher.

5. Sb ２ O ３ , PbO, and As ２ O ３ 1. A method for producing glass, comprising: obtaining a mixture containing a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium; drying the mixture to obtain a dried product containing the glass powder containing the heavy metal oxide and the reducing agent; and mixing the dried product with a halogenating agent and heating the mixture at a temperature of 700° C. or higher.

6. The method for producing glass according to claim 5, wherein the heating temperature is 1000° C. or higher.

7. A method for producing glass according to any one of claims 1, 2 and 5, wherein the atmosphere during the heating contains water vapor and has a dew point temperature of 0°C or higher.

8. A method for producing glass as claimed in any one of claims 1, 2 and 5, wherein the atmosphere during heating contains 30 mass % or less of oxygen among components other than water vapor.

9. A method for producing glass according to any one of claims 1, 2 and 5, wherein the atmosphere during heating contains water vapor, the content of oxygen among components other than the water vapor is 30 mass% or less, and the dew point temperature is 0°C or higher.

10. The mixture is Sb ２ O ３ , PbO, and As ２ O ３ 6. The method for producing glass according to claim 1, wherein the glass is obtained by mixing a glass powder containing at least one heavy metal oxide selected from the group consisting of glass powder and a reducing agent solution.

11. The mixture contains Sb ２ O ３ , PbO, and As ２ O ３ 6. The method for producing glass according to claim 1, further comprising the steps of: mixing a glass material containing at least one heavy metal oxide selected from the group consisting of a glass powder and a reducing agent solution; and then pulverizing the glass material to obtain glass powder.

12. The glass powder contains Sb as the heavy metal oxide. ２ O ３ The method for producing glass according to claim 1 , further comprising:

13. The method for producing glass according to any one of claims 1, 2 and 5, wherein the reducing agent is a water-soluble organic compound.

14. The method for producing glass according to any one of claims 1, 2 and 5, wherein the liquid medium is water.

15. A method for producing glass according to any one of claims 1, 2 and 5, wherein the reducing agent is a sugar.

16. A method for producing glass according to any one of claims 1, 2, and 5, wherein the median diameter d50 of the glass powder is 100 μm or less.

17. The halogenating agent is CaCl ２ , CaCl ２ ・2H ２ The method for producing glass according to claim 3 , wherein the inorganic filler is at least one selected from the group consisting of O and NaCl.

18. The halogenating agent is CaCl ２ , CaCl ２ ・2H ２ The method for producing glass according to claim 5 or 6, wherein the inorganic filler is at least one selected from the group consisting of O and NaCl.

19. A method for producing glass according to any one of claims 1, 2 and 5, wherein at least one of the mixture and the dried product further contains at least one selected from the group consisting of a metal powder containing at least one element selected from Al, Si, Cu and Fe, a water-insoluble organic powder, and a carbon powder.

20. The method for producing glass according to any one of claims 1, 2 and 5, wherein at least one of the mixture and the dried product further contains a glass raw material.

21. The glass powder has a content of SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0 to 10%, and heavy metal oxide: 0.005 to 1%, the content of the heavy metal oxide being Sb ２ O ３ , PbO, and As ２ O ３ The method for producing glass according to claim 1 , 2 or 5 , wherein the total amount of 22. The content of the resulting glass, expressed as mass% on an oxide basis, is SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0 to 10%, heavy metal oxides: 0 to 0.15%, and halogen elements: 0 to 3%, ２ O ３ , PbO, and As ２ O ３ The method for producing glass according to claim 1 , wherein the content of the halogen elements means a total amount of F, Cl, and Br.

23. Sb ２ O ３ , PbO, and As ２ O ３ A mixture comprising a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, the reducing agent being dissolved in the liquid medium.

24. The mixture of claim 23, further comprising a halogenating agent.

25. A dried product obtained by drying a mixture, the mixture being Sb ２ O ３ , PbO, and As ２ O ３ a glass powder containing at least one heavy metal oxide selected from the group consisting of a reducing agent and a liquid medium, wherein the reducing agent is dissolved in the liquid medium.

26. The dried product according to claim 25, wherein the mixture further comprises a halogenating agent, and the dried product further comprises a halogen component derived from the halogenating agent.

27. The oxide content expressed as mass% is SiO ２ :60-80%, Na ２ O: 5-20%, MgO: 0-15%, CaO: 5-20%, Al ２ O ３ : 0 to 10%, heavy metal oxides: 0.001 to 0.15%, and halogen elements: 0.005 to 3%, wherein the content of the heavy metal oxides is Sb ２ O ３ , PbO, and As ２ O ３ and the content of the halogen element means the total amount of F, Cl, and Br.

28. Sb ２ O ３ The Sb present in the glass ３＋ and Sb ５＋ is the molar concentration of [Sb ３＋ ] and [Sb ５＋ ] to obtain [Sb ３＋ ] / ([Sb ３＋ ]+[Sb ５＋ 28. The glass according to claim 27, wherein the Sb-Redox value represented by the formula (1) is 80 to 100%.

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