Water glass, geopolymer, and production methods for water glass and geopolymer

Abstract

There is a demand for: a production method for a water glass in which a raw material can be effectively used; a water glass produced by said production method; a geopolymer in which said water glass is used; and a method for producing said geopolymer.　A production method for a water glass according to the present invention comprises a step for causing a reaction to occur between a soda glass and an alkali solution or an alkali source at a temperature of 65°C or higher while applying pressure thereto.

Description

Water glass, geopolymer, method for producing water glass and geopolymer

[0001] The present invention relates to water glass, a geopolymer, and a method for producing water glass and a geopolymer.

[0002] Water glass is used as a soil conditioner, detergent builder, adhesive, geopolymer, etc. Water glass is known as a highly viscous aqueous solution. Water glass is a solution of sodium silicate (Na ２ O.nSiO ２ (n=2 to 4) (see Patent Document 1 below).

[0003] Patent Document 1 discloses a method for producing water glass using waste glass or recycled glass. The method for producing water glass described in Patent Document 1 includes a step of mixing soda-lime glass (soda glass) with an alkali metal hydroxide solution to form an aqueous sodium silicate fraction, and a step of separating the aqueous sodium silicate fraction from solids.

[0004] Special Publication No. 2022-507481

[0005] In the method for producing water glass described in Patent Document 1, solids remain after mixing soda glass with an alkali metal hydroxide solution. The solids include calcium silicate hydrate and undissolved glass. Therefore, a portion of the soda glass (undissolved glass) prepared as a raw material for producing water glass is not effectively utilized.

[0006] Therefore, a method for producing water glass that allows for effective use of raw materials is desired. Also desired are water glass produced by such a production method, a geopolymer using the water glass, and a method for producing the same.

[0007] A method for producing water glass according to one embodiment includes a step of reacting soda glass with an alkaline solution or an alkaline source at a temperature of 65° C. or higher under pressure.

[0008] A method for producing a geopolymer according to one embodiment includes a mixing step of mixing the water glass obtained by the above-mentioned method for producing water glass with at least one of an active filler containing an alkali source and an aggregate.

[0009] The water glass according to one embodiment is water glass obtained by the above-mentioned method for producing water glass.

[0010] A geopolymer according to one embodiment is formed by mixing the water glass with at least one of an active filler containing an alkali source and an aggregate.

[0011] 1 is a schematic cross-sectional view of a photovoltaic conversion module according to an embodiment, FIG 2 is a schematic perspective view of a crushing device according to an embodiment, and FIG 3 is a schematic cross-sectional view of a crushing device according to an embodiment.

[0012] Hereinafter, embodiments will be described with reference to the drawings. In the following drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the ratios of the dimensions may differ from those of the actual parts.

[0013] A method for producing water glass according to one embodiment includes a step of reacting soda glass with an alkaline solution or an alkaline source under pressure at a temperature of 65° C. or higher. The inventors of the present application have found that this method can suppress the generation of residues of the prepared soda glass and enable the effective use of the soda glass as a raw material.

[0014] An embodiment using an alkaline solution and an embodiment using an alkaline source will be described in more detail below.

[0015] [First embodiment] (Water glass and its manufacturing method) A method for manufacturing water glass according to a first embodiment may include a step of preparing soda glass and an alkaline solution (preparation step), and a step of reacting the soda glass and the alkaline solution at a temperature of 65°C or higher while applying pressure (wet reaction step).

[0016] The alkaline solution may be an aqueous solution containing an alkaline source dissolved therein. The alkaline source may include, for example, at least one selected from the group consisting of an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkali metal carbonate, and an alkaline earth metal carbonate.

[0017] The alkali metal as the alkali source may include at least one selected from the group including, for example, lithium, sodium, potassium, and rubidium. The alkali metal as the alkali source is preferably sodium. The alkaline earth metal as the alkali source may include at least one selected from the group including, for example, magnesium, calcium, strontium, and barium.

[0018] Therefore, the alkaline solution prepared in the preparing step may include at least one selected from the group consisting of an alkali metal hydroxide solution, an alkaline earth metal hydroxide solution, an alkali metal carbonate solution, and an alkaline earth metal carbonate solution. The alkali metal and alkaline earth metal are as described above. Preferably, the alkaline solution is a sodium hydroxide aqueous solution or a sodium carbonate aqueous solution.

[0019] The soda glass prepared in the preparation step is not particularly limited. ２ , Na ２ In addition, soda glass contains MgO, Al ２ O ３ , S.O. ３ The soda glass may contain at least one selected from the group consisting of MgO, Al ２ O ３ and SO ３ Furthermore, the soda glass may optionally contain diantimony trioxide (Sb ２ O ３ ) may contain antimony element.

[0020] SiO in soda glass ２ The concentration of Na in soda glass may be, for example, 65 to 75% by weight or 65 to 73% by weight.２ The concentration of O in the soda glass may be, for example, 10 to 15 wt % or 12.5 to 15 wt %. The concentration of CaO in the soda glass may be, for example, 6 to 12 wt %. The concentration of MgO in the soda glass may be, for example, 0 to 5 wt %. The concentration of Al in the soda glass may be, for example, 10 to 15 wt % or 12.5 to 15 wt %. ２ O ３ The concentration of SO in soda glass may be, for example, 0 to 2% by weight. ３ The concentration of Sb in soda glass may be, for example, 0 to 1% by weight. ２ O ３ The concentration of may be, for example, 0 to 1% by weight. However, it should be noted that these numerical ranges of the concentration are merely examples and are not intended to be limiting.

[0021] Preferably, the soda glass is a crushed cover glass obtained by recycling a photovoltaic conversion panel. The photovoltaic conversion panel may be, for example, a solar panel that converts light energy into electrical energy. The method for producing water glass of the present invention can be suitably applied to the recycling of soda glass used in photovoltaic conversion panels.

[0022] Specifically, the photovoltaic panel has a transparent cover glass on the surface side of the photovoltaic conversion element that converts light energy into electrical energy. The cover glass is made of soda glass. The cover glass (soda glass) may contain additives as needed. For example, the cover glass may contain antimony trioxide (Sb) as an additive to remove air bubbles in the cover glass and improve the transparency of the glass. ２ O ３ A detailed example of a process for recovering soda glass from the cover glass of a photovoltaic conversion panel will be described later.

[0023] The soda glass prepared in the preparation step is preferably in the form of a pulverized product. This makes the soda glass more easily soluble in an alkaline solution in the reaction step described below. From this perspective, the average particle size of the pulverized soda glass may be, for example, in the range of 0.05 mm to 5 mm, preferably in the range of 0.08 mm to 2 mm, and more preferably in the range of 0.01 mm to 1 mm.

[0024] In the first embodiment, the wet reaction step involves mixing soda glass with an alkaline solution, and reacting the soda glass and the alkaline solution under pressure at a temperature of 65° C. or higher. The wet reaction step includes dissolving the soda glass in the alkaline solution.

[0025] The wet reaction step may include heating the soda glass and the alkaline solution to a temperature of, for example, 65°C or higher and 800°C or lower, 110°C or higher and 800°C or lower, 120°C or higher and 700°C or lower, preferably 130°C or higher and 600°C or lower, more preferably 140°C or higher and 500°C or lower, and even more preferably 150°C or higher and 400°C or lower.

[0026] The wet reaction step may include pressurizing the soda glass and the alkaline solution to a pressure of, for example, 0.2 MPa or more and 20 MPa or less, preferably 0.3 MPa or more and 15 MPa or less, more preferably 0.4 MPa or more and 10 MPa or less. Pressurization can make it easier to heat the soda glass and the alkaline solution to a higher temperature.

[0027] In the wet reaction process, the above temperature ranges and pressure ranges can be used in any combination. Furthermore, in the wet reaction process, the alkaline solution may remain in, for example, a liquid phase. Alternatively, in the wet reaction process, the alkaline solution may transition to, for example, a gas phase or a supercritical fluid phase. In this case, the soda glass may be dissolved in the alkaline solution that has returned to a liquid phase after the wet reaction process.

[0028] As described above, by pressurizing the soda glass and the alkaline solution, the soda glass and the alkaline solution can be heated to a higher temperature, for example, a temperature of 65° C. or higher or a temperature of 110° C. or higher. This promotes the reaction between the soda glass and the alkaline solution, making it easier to dissolve the solid (e.g., powdered) soda glass in the alkaline solution. Such pressurization and heating of the soda glass and the alkaline solution can be carried out, for example, by an autoclave.

[0029] The filling rate of the solution relative to the volume of the container of the autoclave may be, for example, 10% or more, preferably 30% or more, more preferably 50% or more, or may be, for example, 100% or less.

[0030] By increasing the heating temperature and pressure, it is possible to almost completely dissolve the soda glass in the alkaline solution. This allows for the effective use of the soda glass as a raw material. Furthermore, it also eliminates the need for a separation step such as centrifugation after the wet reaction step, thereby simplifying the water glass manufacturing process.

[0031] The hydroxide concentration or carbonate concentration of the alkaline solution in the wet reaction step is not particularly limited. From the viewpoint of dissolving soda glass, it is desirable that the hydroxide concentration or carbonate concentration of the alkaline solution be high. However, since the reaction between the soda glass and the alkaline solution can be promoted by heating and pressurizing the alkaline solution, the hydroxide concentration or carbonate concentration of the alkaline solution may be relatively low. From this viewpoint, the alkaline solution may have a hydroxide concentration or carbonate concentration of less than 1 M. Even in this case, it is possible to almost completely dissolve the soda glass in the alkaline solution by increasing the heating temperature and pressure in the wet reaction step. Furthermore, the lower limit of the hydroxide concentration or carbonate concentration of the alkaline solution may be, for example, 0.4 M or more, preferably 0.6 M or more, and more preferably 0.8 M or more.

[0032] At the time when the soda glass and the alkali solution start to be mixed, the molar ratio of silica to alkali metal (SiO ２ / A ２ O) (A is an alkali metal) is preferably 5.0 or less, and more preferably 2.0 to 5.0. It is preferable to adjust the concentration of the alkali metal in the alkaline solution so as to achieve such a molar ratio.

[0033] The reaction time between the soda glass and the alkaline solution in the wet reaction step may be any time long enough to fully dissolve the soda glass in the alkaline solution. In this embodiment, the reaction time can be shortened by increasing the heating temperature and pressure. From this perspective, the reaction time may be, for example, 5 minutes to 20 hours, preferably 10 minutes to 15 hours, more preferably 20 minutes to 10 hours, and even more preferably 30 minutes to 5 hours. Even in this case, it is possible to almost completely dissolve the soda glass in the alkaline solution. This also makes it possible to shorten the production time of water glass.

[0034] Water glass is obtained by the wet reaction process. Water glass is mainly composed of Na ２ O.nSiO ２ (n=2 to 4). The water glass may contain at least one element selected from the group consisting of elements contained in the soda glass as a raw material, such as Mg, Al, S, and Sb.

[0035] Here, when the prepared soda glass is a cover glass of a photoelectric conversion module, the soda glass contains, as described above, MgO, Al ２ O ３ , S.O. ３ , and / or Sb ２ O ３ These additives may be one of the factors that make the soda glass less soluble in the alkaline solution in the wet reaction step. Even in such a case, in the first embodiment, the soda glass is heated to a high temperature of 65°C or higher while being pressurized in the wet reaction step, which makes it easy to dissolve almost all of the solid soda glass. From the viewpoint of dissolving the soda glass, it is preferable that the pressure and temperature are as high as possible.

[0036] [Second embodiment] (Water glass and manufacturing method thereof) A manufacturing method of water glass according to a second embodiment may include a step of preparing soda glass and an alkali source (preparation step), a step of reacting the soda glass and the alkali source at a temperature of 65°C or higher while applying pressure (dry reaction step), and a step of dissolving the cullet obtained in the dry reaction step in a solvent (dissolution step). In the second embodiment, the alkali source to be prepared may be a solid, for example, in powder form.

[0037] The alkalinity source may include, for example, at least one selected from the group including alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, and alkaline earth metal carbonates.

[0038] The alkali metal as the alkali source may include at least one selected from the group including, for example, lithium, sodium, potassium, and rubidium. The alkali metal as the alkali source is preferably sodium. The alkaline earth metal as the alkali source may include at least one selected from the group including, for example, magnesium, calcium, strontium, and barium.

[0039] Preferably, the alkaline source is sodium hydroxide or sodium carbonate.

[0040] The composition and form of the soda glass prepared in the preparation step are the same as those in the first embodiment, and therefore a description thereof will be omitted. Also, as in the first embodiment, the soda glass may be crushed cover glass obtained by recycling photovoltaic conversion panels.

[0041] In a second embodiment, the dry reaction process involves melting soda glass and an alkali source under pressure and heating to above 65° C., followed by cooling to form cullet.

[0042] The dry reaction step includes heating the soda glass and the alkali source to a temperature of, for example, 600°C or higher and 1500°C or lower, preferably 800°C or higher and 1300°C or lower, and more preferably 1000°C or higher and 1200°C or lower.

[0043] The dry reaction step may include pressurizing the soda glass and the alkali source to a pressure of, for example, 0.2 MPa or more and 40 MPa or less, preferably 0.3 MPa or more and 30 MPa or less, more preferably 0.4 MPa or more and 20 MPa or less. Pressurization allows the soda glass and the alkali source to be dissolved at a lower temperature.

[0044] At the time of mixing the soda glass and the alkali source, the molar ratio of silica to alkali metal (SiO ２ / A ２ O) (A is an alkali metal) is preferably 5.0 or less, and more preferably 2.0 to 5.0. It is preferable to adjust the concentration of the alkali metal in the alkali source so as to achieve such a molar ratio.

[0045] In the second embodiment, the soda glass and the alkali source are melted and then solidified into cullet, so that no soda glass residue is essentially generated in the dry reaction process.

[0046] Here, when the prepared soda glass is a cover glass of a photoelectric conversion module, the soda glass contains, as described above, MgO, Al ２ O ３ , S.O. ３ , and / or Sb ２ O ３ These additives may be one of the factors that make it difficult for the soda glass to melt in the dry reaction step. Even in such a case, in the second embodiment, the soda glass is heated to a high temperature while being pressurized in the dry reaction step, so that it is easy to melt almost all of the solid soda glass. From the viewpoint of melting the soda glass, it is preferable that the pressure and temperature are as high as possible.

[0047] Next, the dissolving step involves dissolving the cullet obtained in the dry reaction step in a solvent, which may be water, to obtain water glass.

[0048] The dissolving step may include heating the solvent containing the cullet. Heating the solvent containing the cullet can make it easier to dissolve the cullet in the solvent. The heating temperature for dissolving the cullet in the solvent may be, for example, 65°C or higher, preferably 90°C or higher.

[0049] The dissolving step may include pressurizing and heating the solvent containing the cullet. Such pressurizing and heating of the solvent containing the cullet can be performed, for example, using an autoclave. By pressurizing, the solvent containing the cullet can also be heated to a higher temperature. This makes it easier to dissolve the cullet in the solvent.

[0050] Water glass is obtained through the melting process. The composition of the water glass is the same as that of the first embodiment, so a description thereof will be omitted.

[0051] (Uses of water glass)

[0052] The water glass produced as described in the first and second embodiments can be used as a soil conditioner, a builder for detergents, an adhesive, a geopolymer, and the like.

[0053] In one aspect, the geopolymer is formed by mixing water glass obtained by the above-described method for producing water glass (see the first and second embodiments) with at least one of an active filler containing an alkali source and an aggregate. Specifically, the method for producing a geopolymer includes a mixing step of mixing the water glass obtained by the above-described method for producing water glass with at least one of an active filler containing an alkali source and an aggregate. The geopolymer is produced through the mixing step. If necessary, the mixing step may include heating the mixture with steam while pressurizing it.

[0054] In one example, the geopolymer is made by mixing water glass obtained by the above-mentioned water glass manufacturing method (see the first and second embodiments) with an active filler containing an alkali source. In this case, aggregate does not need to be mixed.

[0055] In another example, the geopolymer is made by mixing the water glass obtained by the above-mentioned water glass manufacturing method (see the first and second embodiments) with aggregate. In this case, the active filler does not need to be mixed.

[0056] Preferably, the geopolymer is formed by mixing water glass obtained by the above-mentioned method for producing water glass (see the first and second embodiments), an active filler containing an alkali source, and an aggregate.

[0057] The aggregate is used to harden the water glass to form the geopolymer and may include any known material, for example, sand.

[0058] Alternatively, the aggregate may contain, for example, crushed soda glass. In this case, the soda glass may be crushed cover glass obtained by recycling photovoltaic panels. In this case, the geopolymer manufacturing method can be suitably applied to the recycling of soda glass used in photovoltaic panels. Furthermore, since the components of the geopolymer contain a large amount of soda glass, the geopolymer can be easily recycled.

[0059] The active filler preferably includes alumina. Specifically, the active filler may include at least one selected from the group including fly ash, blast furnace slag, and fumed silica.

[0060] The alkalinity source in the active filler may include, for example, at least one selected from the group including alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, and alkaline earth metal carbonates.

[0061] The alkali metal as the alkali source in the active filler may include at least one selected from the group including, for example, lithium, sodium, potassium, and rubidium. The alkaline earth metal as the alkali source may include at least one selected from the group including, for example, magnesium, calcium, strontium, and barium.

[0062] When water glass and active filler are mixed, the alkali source in the active filler dissolves, allowing the alkali concentration in the water glass to be adjusted as needed for geopolymer production.

[0063] The active filler may include, for example, crushed soda glass. In this case, the soda glass may be crushed cover glass obtained by recycling photovoltaic panels. In this case, the method for producing a geopolymer can be suitably applied to the recycling of soda glass used in photovoltaic panels. Furthermore, since the components of the geopolymer contain a large amount of soda glass, the geopolymer can be easily recycled.

[0064] The soda glass used as aggregate and / or active filler is SiO ２ , Na ２ In addition, soda glass may contain MgO, Al, and CaO as its main components. ２ O ３ , S.O. ３ The soda glass may contain at least one selected from the group consisting of MgO, Al ２ O ３ and SO ３ Furthermore, the soda glass may optionally contain diantimony trioxide (Sb ２ O ３ ) may contain antimony element.

[0065] SiO in soda glass used as aggregate and / or active filler ２ The concentration of Na in soda glass may be, for example, 65 to 75% by weight or 65 to 73% by weight. ２ The concentration of O in the soda glass may be, for example, 10 to 15 wt % or 12.5 to 15 wt %. The concentration of CaO in the soda glass may be, for example, 6 to 12 wt %. The concentration of MgO in the soda glass may be, for example, 0 to 5 wt %. The concentration of Al in the soda glass may be, for example, 10 to 15 wt % or 12.5 to 15 wt %. ２ O ３ The concentration of SO in soda glass may be, for example, 0 to 2% by weight. ３ The concentration of Sb in soda glass may be, for example, 0 to 1% by weight.２ O ３ The concentration of may be, for example, 0 to 1% by weight. However, it should be noted that these numerical ranges of the concentration are merely examples and are not intended to be limiting.

[0066] In addition, the water glass can be used not only for geopolymer applications but also for the production of crystalline sodium silicate. Crystalline sodium silicate, such as sodium metasilicate, is produced by mixing the water glass with a caustic soda solution to a molar ratio of 1 or less, cooling or concentrating the mother liquor to make it supersaturated, and then precipitating and growing crystals.

[0067] (Recycling of cover glass in photovoltaic conversion panel) Next, as an example of a method for obtaining soda glass as a raw material for water glass, aggregate and / or active filler, recovery of cover glass used in photovoltaic conversion modules will be described. First, an example of the configuration of a photovoltaic conversion module that can be recycled will be described. Fig. 1 is a schematic cross-sectional view of a photovoltaic conversion module according to one embodiment.

[0068] 1 , the photovoltaic conversion module 10 includes a photovoltaic conversion panel 20 and a frame 30 that surrounds the outer edge of the photovoltaic conversion panel 20. A junction box and an output cable (not shown) that serve as power outlets may be attached to the rear surface of the photovoltaic conversion module 10.

[0069] The sealing material 40 may be provided between the photoelectric conversion panel 20 and the frame 30. The material constituting the sealing material 40 is not particularly limited, but examples thereof include resin materials such as polyethylene resin, fluorine resin, polystyrene resin, polyolefin resin, silicone resin, and butyl rubber.

[0070] The photoelectric conversion panel 20 may include a photoelectric conversion element 21, a rear protective layer 22, a cover glass 23, a first sealing layer 24, and a second sealing layer 25. The cover glass 23 may be, for example, transparent or translucent soda glass. The soda glass may be, for example, tempered glass. The composition of the soda glass is as described above.

[0071] The first sealing layer 24 is disposed between the photoelectric conversion element 21 and the cover glass 23. Examples of materials that can be used to form the first sealing layer 24 include ethylene vinyl acetate resin, polyethylene resin, fluorine resin, polystyrene resin, polyolefin resin, silicone resin, and butyl rubber.

[0072] The second sealing layer 25 is provided between the photoelectric conversion element 21 and the back-side protective layer 22. The material constituting the second sealing layer 25 is not particularly limited, but examples thereof include ethylene vinyl acetate resin, polyethylene resin, fluorine resin, polystyrene resin, polyolefin resin, silicone resin, and butyl rubber.

[0073] The rear protective layer 22 is a protective layer that covers the rear surface of the photovoltaic conversion panel 20. The rear protective layer 22 is provided on the rear surface of the second sealing layer 25. The material constituting the rear protective layer 22 may be, for example, a PET resin, a PVF (polyvinyl fluoride) resin, a PVDF (polyvinylidene fluoride) resin, a nylon resin, a polyamide resin, or a combination thereof. Alternatively, the rear protective layer 22 may be made of a metal sheet.

[0074] The photoelectric conversion element 21 is an element that converts light energy into electrical energy and vice versa. The photoelectric conversion element 21 may have any configuration that allows for conversion between light energy and electrical energy and vice versa. Examples of such elements include crystalline photoelectric conversion elements and thin-film CIS-type photoelectric conversion elements. Many crystalline photoelectric conversion elements have a structure in which semiconductor silicon is used as a substrate. Specifically, a crystalline silicon-based photoelectric conversion element may include multiple battery cell units made of a silicon substrate.

[0075] Next, a method for recovering the cover glass 23, i.e., the soda glass, from the photovoltaic conversion module 10 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a schematic perspective view of a crushing device according to one embodiment. Fig. 3 is a schematic cross-sectional view of the crushing device according to one embodiment.

[0076] First, the frame 30 is removed from the photovoltaic conversion module 10. At this time, a junction box (not shown) and the like may also be removed from the photovoltaic conversion module 10. As a result, the photovoltaic conversion panel 20 is taken out from the photovoltaic conversion module 10.

[0077] Next, the cover glass 23 is separated from the photoelectric conversion panel 20. The cover glass 23 can be peeled off, for example, by pressing a blade from the side against the position of the first sealing layer 24 between the cover glass 23 and the photoelectric conversion element 21.

[0078] Next, the separated cover glass 23 is crushed to obtain crushed soda glass. The method for crushing the cover glass 23 is not particularly limited. The cover glass 23 may be crushed using, for example, a single-shaft crusher having a bit-shaped blade on a rotating shaft that continuously crushes a structure while biting into it with a fixed blade, a double-shaft crusher that crushes a workpiece by clamping it between rotating blades, or a crusher that continuously crushes the workpiece by hitting it with a high-speed rotating hammer until it becomes equal to or smaller than a desired size.

[0079] Preferably, the crushed soda glass may be crushed into fine powder having a smaller average particle size by, for example, a crushing device shown in Figures 2 and 3. The crushing device 120 may have a crushing mechanism 122 having an upper plate 122a and a lower plate 122b. The upper plate 122a and the lower plate 122b are arranged opposite to each other and spaced apart from each other.

[0080] The upper plate 122a and the lower plate 122b are configured to be relatively movable. Here, "relative movement" includes any of the following: the upper plate 122a moving relative to the lower plate 122b, the lower plate 122b moving relative to the upper plate 122a, and both the upper plate 122a and the lower plate 122b moving. Typically, either one of the upper plate 122a or the lower plate 122b may be movable relative to the other of the upper plate 122a or the lower plate 122b.

[0081] The upper plate 122a and the lower plate 122b may have a pair of surfaces 123a, 123b facing each other. Specifically, the lower surface 123a of the upper plate 122a faces the upper surface 123b of the lower plate 122b. The pair of surfaces 123a, 123b may be surfaces with high friction and may have a plurality of grooves. The pair of surfaces 123a, 123b are configured to be relatively movable in a direction along the pair of surfaces 123a, 123b due to relative movement between the upper plate 122a and the lower plate 122b.

[0082] The gap between the pair of surfaces 123a, 123b forms a space in which crushed objects can be placed. The upper plate 122a has an inlet 124 for introducing crushed objects. Crushed objects (crushed cover glass objects) introduced through the inlet 124 are placed between the pair of surfaces 123a, 123b from the upper surface 123b of the lower plate 122b. Specifically, when multiple crushed objects are introduced through the inlet 124, the crushed objects spread around due to vibrations caused by the relative movement of the upper plate 122a and the lower plate 122b, and can be placed between the pair of surfaces 123a, 123b. Furthermore, the upper surface 123b may be made convex or have desired grooves formed in it, making it easier for the crushed objects to spread around and be placed between the pair of surfaces 123a, 123b.

[0083] The relative movement of the pair of surfaces 123a, 123b is preferably a rotational movement with an axis 125 that intersects with the pair of surfaces. Of the pair of surfaces, the upper surface 123a preferably has a tapered surface that slopes downward from near the center near the inlet 124 toward the outside. As a result, the distance between the pair of surfaces 123a, 123b gradually decreases from near the center near the inlet 124 toward the outside. Due to the relative rotational movement of the pair of surfaces 123a, 123b, the crushed material introduced into the inlet 124 moves from near the center toward the outside and is discharged to the outside. As a result, the crushed material is subjected to shearing force while being sandwiched between the pair of surfaces 123a, 123b, and is further crushed into smaller pieces.

[0084] The average particle size of the soda glass thus pulverized may be, for example, in the range of 0.05 mm to 5 mm, preferably in the range of 0.08 mm to 2 mm, and more preferably in the range of 0.01 mm to 1 mm. The soda glass thus pulverized can be suitably used as a raw material for water glass and / or aggregate.

[0085] [Example 1] A method for producing water glass according to Example 1 will be described. First, soda glass was prepared. The soda glass was a cover glass separated from a solar panel (manufactured by Kyocera) using a panel separator. The cover glass was crushed to prepare soda glass in the form of a crushed material.

[0086] SiO in soda glass ２ The concentration of Na in the soda glass was 71% by weight. ２ The concentration of O in the soda glass was 13 wt %. The concentration of CaO in the soda glass was 9.1 wt %. The concentration of MgO in the soda glass was 4.2 wt %. The concentration of Al in the soda glass was 13 wt %. ２ O ３ The concentration of SO in the soda glass was 1.2 wt %. ３ The concentration of Sb in the soda glass was 0.2 wt %. ２ O ３ The concentration was 0.2% by weight.

[0087] 10 g of this soda glass, 4 g of sodium hydroxide (NaOH), and 105 g of water were placed in an autoclave and heated at 8 kgf / cm ２ The mixture was heated at 200° C. for 3 hours while being pressurized at a pressure of approximately 0.78 MPa (wet reaction step).

[0088] When 13% 6 mol / L hydrochloric acid was added to the solution recovered from the autoclave, it was confirmed that the solution gelled into an agar-like gel within a few seconds, confirming that water glass was being produced in the autoclave.

[0089] In Example 1, no solid content (residue) of soda glass was found in the water glass.

[0090] Comparative Example 1 A method for producing water glass according to Comparative Example 1 will be described. In Comparative Example 1, the same soda glass as in Example 1 was prepared by the same method.

[0091] 10 g of this soda glass, 4 g of sodium hydroxide (NaOH), and 105 g of water were mixed at 90° C. under atmospheric pressure for 3 hours.

[0092] This confirmed that water glass was produced. However, in Comparative Example 1, solid soda glass (residue) remained in the water glass, and the soda glass was not completely dissolved.

[0093] As described above, the contents of the present invention have been disclosed through the embodiments, but the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure. Therefore, the technical scope of the present invention is defined only by the inventive features of the claims that can be reasonably understood from the above description.

[0094] This application claims priority based on Japanese Patent Application No. 2024-054074, filed on March 28, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A method for producing water glass, comprising the step of reacting soda glass with an alkaline solution or an alkaline source at a temperature of 65°C or higher under pressure.

2. The method for producing water glass according to claim 1, wherein the alkaline solution includes at least one selected from the group consisting of an alkali metal hydroxide solution, an alkaline earth metal hydroxide solution, an alkali metal carbonate solution, and an alkaline earth metal carbonate solution, and the step includes dissolving the soda glass in the alkaline solution.

3. The method for producing water glass according to claim 2, wherein the step includes heating the soda glass and the alkaline solution to a temperature of 65°C or higher and 800°C or lower.

4. The method for producing water glass according to claim 2 or 3, wherein the step includes pressurizing the soda glass and the alkaline solution to a pressure of 0.2 MPa or more and 20 MPa or less.

5. The method for producing water glass according to any one of claims 2 to 4, wherein the reaction time in the step is 5 minutes or more and 20 hours or less.

6. The method for producing water glass according to any one of claims 2 to 5, wherein the alkaline solution has a hydroxide concentration or a carbonate concentration of less than 1M.

7. The method for producing water glass according to claim 1, wherein the alkali source comprises at least one selected from the group consisting of an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkali metal carbonate, and an alkaline earth metal carbonate, and the step comprises forming cullet by melting the soda glass and the alkali source and then cooling them.

8. The method for producing water glass according to claim 7, wherein the step includes heating the soda glass and the alkali source to a temperature of 600°C or higher and 1500°C or lower.

9. The method for producing water glass according to claim 7 or 8, wherein the step includes pressurizing the soda glass and the alkali source to a pressure of 0.2 MPa or more and 40 MPa or less.

10. A method for producing water glass according to any one of claims 7 to 9, further comprising a step of dissolving the cullet in a solvent.

11. A method for producing water glass according to any one of claims 1 to 10, wherein the soda glass is a crushed cover glass obtained by recycling photovoltaic conversion panels.

12. A method for producing water glass according to any one of claims 1 to 11, wherein the soda glass contains antimony.

13. A method for producing a geopolymer, comprising a mixing step of mixing water glass obtained by the method for producing water glass according to any one of claims 1 to 12 with at least one of an active filler containing an alkali source and an aggregate.

14. The method for producing a geopolymer described in claim 13, wherein the mixing step includes mixing the water glass with the aggregate, and the aggregate includes crushed cover glass obtained by recycling photovoltaic conversion panels.

15. The method for producing a geopolymer described in claim 13 or 14, wherein the mixing step includes mixing the active filler, and the active filler includes crushed cover glass obtained by recycling photovoltaic conversion panels.

16. Water glass obtained by the method for producing water glass according to any one of claims 1 to 12.

17. A geopolymer comprising the water glass according to claim 16 mixed with at least one of an active filler containing an alkali source and an aggregate.

18. The geopolymer of claim 17, wherein the active filler comprises crushed cover glass contained in a photovoltaic panel.

19. The geopolymer of claim 17 or 18, wherein the aggregate comprises crushed cover glass contained in a photovoltaic panel.

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