Recycling method of solar cell module

Abstract

To select and separate blanks constituting a solar cell module.SOLUTION: This recycling method of a solar cell module comprises: a preparation step of preparing a solar cell sheet-like structure including, with a glass substrate and a frame member removed from the solar cell module, at least a solar cell, a metal pattern wired from the solar cell, a sealing material that seals these, a protection member provided on one surface of the sealing material, and a glass residue derived from the glass substrate and remaining on the surface of the sealing material; a crushing step of crushing the solar cell sheet-like structure to form a crushed article; a classification step of classifying the crushed article into fine powder which is small in particle size and coarse powder which is large in particle size and collecting the fine powder; a pulverization step of pulverizing the fine powder to provide a pulverized article; a wet specific gravity selection step of selecting wet specific gravity of the pulverized article by using a selection liquid containing a surfactant, and separating it into heavy specific gravity powder and light specific gravity powder; and a heat treatment step of heat-treating the light specific gravity powder to provide a heat-treated article.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for recycling solar cell modules. [Background technology]

[0002] Solar cell power generation is drawing attention as a renewable energy source because it utilizes clean energy, namely sunlight, and has a small environmental impact. A solar cell module used in this solar cell power generation is configured, for example, with solar cells, a sealant that seals the solar cells, a protective member (a so-called back sheet), a metal pattern that is wired from the solar cells, a glass substrate, and a frame member that is provided around the sealant.

[0003] Until now, solar cell modules have been disposed of after a certain period of use, but in recent years, there has been a demand to process solar cell modules and recover valuable metals for recycling.

[0004] In view of this, for example, Patent Document 1 discloses a method for treating solar cell modules. Patent Document 1 describes a method in which a solar cell sheet structure obtained by removing glass substrates and the like from a solar cell module is crushed, and the crushed material is then classified, crushed, and subjected to wet specific gravity separation to separate particles containing metal from particles containing resin and particles containing metallic silicon, and to concentrate the metal components. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent application 2021-182486 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, solar cell modules contain not only valuable metal components but also metallic silicon and the like derived from solar cell cells. Therefore, from the viewpoint of recycling solar cell modules, it is required not only to concentrate valuable metal components but also to separate and sort the members constituting the solar cell module by material.

[0007] An object of the present invention is to provide a technique for sorting and separating the various materials that make up a solar cell module. [Means for solving the problem]

[0008] The first aspect of the present invention is a preparation step of removing a glass substrate and a frame member from a solar cell module to prepare a solar cell sheet-like structure comprising at least solar cells, a metal pattern wired from the solar cells, a sealant for sealing them, a protective member provided on one side of the sealant, and glass residue derived from the glass substrate and remaining on the surface of the sealant; a crushing step of crushing the solar cell sheet structure to form a crushed product; A classification step of classifying the crushed material into fine powder having a small particle size and coarse powder having a large particle size and collecting the fine powder; A grinding step of grinding the fine powder to obtain a ground product; a wet specific gravity sorting step in which the pulverized material is subjected to wet specific gravity sorting using a sorting liquid containing a surfactant to separate the pulverized material into a heavy specific gravity powder and a light specific gravity powder; A heat treatment step of heat treating the low specific gravity powder to obtain a heat-treated product. This is a method for recycling solar cell modules.

[0009] The second aspect of the present invention is the method according to the first aspect, The low specific gravity powder contains at least particles containing metallic silicon derived from the solar cell, and particles containing glass derived from the glass substrate.

[0010] A third aspect of the present invention is the method according to the first or second aspect, When the wet specific gravity sorting step is the first specific gravity sorting step, the method further includes a second specific gravity sorting step, which is performed after the heat treatment step, by wet specific gravity sorting the heat-treated product using a sorting liquid containing a surfactant.

[0011] The fourth aspect of the present invention is the first to third aspects, In the heat treatment step, the heating temperature is set to 500° C. or more and 800° C. or less.

[0012] The fifth aspect of the present invention is the first to fourth aspects, In the pulverizing step, the micropowder is subjected to compression pulverization or impact pulverization.

[0013] The sixth aspect of the present invention is the first to fifth aspects, The fine powder includes at least particles containing a metal component, particles containing metallic silicon, bonded particles in which the metal component and the metallic silicon are bonded together, and particles containing glass.

[0014] The seventh aspect of the present invention is the first to sixth aspects, The particle size of the fine powder is 1 μm or more and 500 μm or less.

[0015] The eighth aspect of the present invention is the first to seventh aspects, In the pulverization step, the fine powder is pulverized so that the particle size of the pulverized product is 1 μm or more and 450 μm or less.

[0016] A ninth aspect of the present invention is the first to eighth aspects, In the wet density separation step, a mixed slurry obtained by mixing the pulverized material with the separating liquid is supplied to a thin flow separator, and wet density separation is performed.

[0017] A tenth aspect of the present invention relates to the ninth aspect, The mixed slurry supplied to the thin flow separator is subjected to wet density separation while flowing washing water containing a surfactant. Effect of the Invention

[0018] According to the present invention, the materials constituting the solar cell module can be selected and separated. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view of a solar cell module. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a solar cell sheet structure. [Diagram 3] FIG. 3 is a diagram showing a flow of a solar cell module recycling method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present inventors have focused on the method shown in Patent Document 1, in which heavy specific gravity powder containing metal components and light specific gravity powder containing metal silicon are separated by wet specific gravity sorting, and then the metal silicon contained in the light specific gravity powder is recovered as a recycling material. However, it has been confirmed that the light specific gravity powder contains not only particles containing metal silicon (hereinafter also referred to as metal Si particles) but also particles containing glass (hereinafter also referred to as glass particles), and these are mixed together.

[0021] Although the solar cell sheet structure is formed by removing the glass substrate and the frame member from the solar cell module, the glass substrate cannot be completely removed. Methods for removing the glass substrate include blasting and hot knife methods, but glass residues derived from the glass substrate may adhere to the surface of the sealing material in the solar cell sheet structure. These glass residues become glass particles when the solar cell sheet structure is crushed. The glass particles are then mixed into the light specific gravity powder separated by wet specific gravity sorting.

[0022] Therefore, the inventors of the present invention have investigated a method for separating metal Si particles and glass particles from a mixed state by sorting them separately. Because it is difficult to separate these particles based on their electrical conductivity or electrostatic charge, they have focused on the difference in their specific gravity and investigated separation by wet specific gravity sorting.

[0023] However, it was confirmed that metal Si particles and glass particles derived from solar cell modules form aggregates when they come into contact with water, etc., and therefore cannot be separated by specific gravity difference in their original state. Although metal Si and glass generally tend to be hydrophilic, it was found that metal Si particles and glass particles derived from solar cell modules lose their hydrophilicity and show hydrophobicity. The reason for this is presumed to be that resin components derived from the sealing material, etc., are attached to the metal Si particles and glass particles. In solar cell modules, the glass substrate and the sealing material are in close contact with each other, and the solar cell is in close contact with the sealing material, so that the surfaces of the glass particles and metal Si particles obtained by crushing these have resin components derived from the sealing material, etc. attached to them. It is believed that the hydrophilicity inherent to the metal Si particles and glass particles is lost due to the attached resin components, which causes aggregation when they come into contact with water.

[0024] From the viewpoint of promoting dispersion of the particles in water, it is conceivable to use, for example, a surfactant, but this may not realize dispersion reliably.

[0025] Therefore, the present inventors have investigated a method for suppressing the formation of aggregates of metal Si particles and glass particles. As a result, they have found that it is effective to subject these particles to a heat treatment. By the heat treatment, it is possible to remove the resin components attached to the surfaces of the metal Si particles and glass particles, and the inherent hydrophilicity of these particles can be restored, and the dispersibility in water can be improved.

[0026] The present invention has been made based on the above findings.

[0027] <One embodiment of the present invention> An embodiment of the present invention will now be described, in which a schematic configuration of a solar cell module to be recycled will first be described, and then a method for recycling the solar cell module will be described.

[0028] (1) Solar cell module The solar cell module will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view of the solar cell module. The solar cell module 1 is configured to include, for example, a plurality of solar cells 11, a metal pattern 12 wired from the solar cells 11, a sealant 13 that seals the solar cells 11 and the metal pattern 12, a protective member 14 provided on one side of the sealant 13, a glass substrate 15 provided on the other side of the sealant 13, and a frame member 16 that surrounds the periphery of a laminate including the sealant 13 and the glass substrate 15.

[0029] In the solar cell module 1, the solar cell 11 is formed of a semiconductor containing, for example, metal silicon. The metal pattern 12 is a metal member that is wired from the solar cell 11, and is configured to include, for example, a surface electrode provided on the surface of the solar cell 11 and a bus bar electrode that electrically connects the solar cell 11. The metal pattern 12 contains a valuable metal such as copper (Cu) or silver (Ag), the surface electrode is mainly formed of Ag, and the bus bar electrode is mainly formed of Cu. The sealing material 13 is formed of a resin such as ethylene-vinyl acetate copolymer (EVA) or polyethylene. The protective member 14 is formed of a resin such as polyethylene terephthalate or fluororesin. The glass substrate 15 is formed of, for example, glass. The frame member 16 is formed of, for example, a metal or a resin.

[0030] In order to select the constituent materials of the solar cell module 1, the glass substrate 15 and frame member 16 are removed in advance, and the solar cell module 1 is processed in the form of a solar cell sheet-like structure 10 shown in Fig. 2. A conventionally known method can be used to remove the glass substrate 15 and the frame member 16. In the solar cell sheet-like structure 10, glass residue (not shown) that remains after the glass substrate 15 has not been completely removed adheres to the surface of the sealing material 13.

[0031] (2) How to recycle solar cell modules The recycling method of this embodiment includes a preparation step, a crushing step, a classification step, a pulverization step, a first specific gravity sorting step, a heat treatment step, and a second specific gravity sorting step, as shown in Fig. 3. Fig. 3 is a diagram showing the flow of the recycling method of a solar cell module according to one embodiment of the present invention. Each step will be described below.

[0032] (preparation process) First, the solar cell sheet structure 10 to be subjected to the crushing step is prepared.

[0033] The solar cell sheet structure 10 is obtained by removing the glass substrate 15 and the frame member 16 from the solar cell module 1 by a conventionally known method.

[0034] (Crushing process) Next, the solar cell sheet-like structure 10 is crushed as it is to form crushed material. The crushed material contains particles derived from the constituent members of the solar cell sheet-like structure 10. Specifically, the crushed material contains particles containing metal Si (metal Si simple particles, etc.) derived from the solar cell 11, particles containing a metal component (metal simple particles, etc.) derived from the metal pattern 12, particles containing a resin (resin simple particles, etc.) derived from the sealing material 13 or the protective member 14, and bonded particles in which a metal component and metal Si are bonded. The crushed material also contains glass particles derived from glass residue. As described above, the resin component derived from the sealing material 13 adheres to the surfaces of the metal Si particles and the glass particles.

[0035] Here, the bonded particles refer to particles formed by crushing the contact points between the solar cell 11 and the surface electrode containing Ag. The surface electrode is formed, for example, by applying Ag paste onto the solar cell 11 and baking it, so that the metal component such as Ag and the metal Si constituting the solar cell 11 are bonded. For this reason, when crushed, the metal component and the metal Si may not separate but remain bonded, forming a bonded particle. The bonded particles are formed by bonding a core particle and an outer shell covering a part of its surface, reflecting the stacked shape of the original solar cell sheet-like structure 10, and when the outer shell covers a part of the surface of the core particle and exists in a band shape, it is also called a single-edged shape. The bonded particles include, for example, particles with a high silicon ratio in which a metal component is bonded as an outer shell to the surface of a metal Si particle that is a core, and particles with a high metal ratio in which a metal Si is bonded as an outer shell to the surface of a metal particle that is a core.

[0036] Each particle contained in the crushed material has a particle size according to the constituent material. For example, the softer and more viscous the material, such as resin, the more coarsely it is crushed, while the harder and more brittle the material, such as metal components, metal silicon, or glass, the more finely it is crushed. Therefore, the particle size of particles containing resin (such as resin particles alone) is relatively large, while the particle size of particles containing other components (such as metal particles alone) is relatively small. In other words, in the crushed material, the larger particle size range contains a lot of resin and the like, and the ratio of metal components is low, while the smaller particle size range is less likely to contain resin and the ratio of metal components is high.

[0037] The size of the crushed material is not particularly limited, but from the viewpoint of suitably separating the resin particles from other particles during the classification process described below, it is preferable to crush the sheet-like structure 10 so that the particle size of the crushed material is 100 mm or less. More preferably, it is crushed to 50 mm or less, even more preferably 20 mm or less, and particularly preferably 10 mm or less. By crushing in this manner, the particle size distribution of the particles contained in the crushed material can be broadened and the particle size can be appropriately varied, and the proportion of metal components contained in the crushed material on the smaller particle size side can be increased. The lower limit of the particle size of the crushed material is not particularly limited.

[0038] As a crushing method, from the viewpoint of appropriately varying the particle size of the particles contained in the crushed material depending on the material, shear crushing that can apply a shearing action to the sheet-like structure 10 is preferable. As the crusher to be used, for example, a known crusher such as a single-shaft crusher or a biaxial crusher can be used, but a single-shaft crusher is preferable. In a biaxial crusher, the crushed material is crushed uniformly finely depending on the crushing conditions, and the particle size is likely to be uniform, whereas in a single-shaft crusher, the crushing is rough, and the particle size of the crushed material obtained is uneven, and the particle size distribution is likely to be wide. In other words, the single-shaft crusher can maintain the particle size of the resin-containing particles relatively large without crushing the sealing material 13 and the protective member 14 excessively finely. As a single-shaft crusher, there are a single-shaft cutter mill and a single-shaft hammer mill depending on the shape of the blade, but from the viewpoint of shear crushing, a single-shaft cutter mill is preferable.

[0039] The crushing conditions are not particularly limited, and the number of blades in the crusher, the blade clearance, the blade rotation speed, etc. may be appropriately adjusted so that the particle size distribution of the crushed material becomes wide. The sheet-like structure 10 may be crushed in one step, or may be gradually crushed in multiple steps such as primary crushing and secondary crushing.

[0040] (Classification process) The crushed material thus obtained is then classified into fine powder having a small particle size and coarse powder having a large particle size, and the fine powder is collected.

[0041] As described above, the crushed material mainly includes coarse powders composed of resin particles and fine powders composed of metal particles, metal silicon particles, bonded particles, etc. By recovering the fine powders from the crushed material by classification, the resin components can be removed and the metal components can be concentrated. The fine powders include glass particles and resin particles pulverized in the crushing process in addition to metal particles, metal silicon particles, and bonded particles.

[0042] The range of particle size collected as fine powder during classification is not particularly limited, but the upper limit is preferably 500 μm or less, more preferably 250 μm or less. The smaller the particle size of the powder, the less impurities such as resin are taken in, and the higher the ratio of valuable metals contained in the fine powder can be. By collecting fine particles having the above particle size range from the crushed material as fine powder, the recovery rate can be increased while maintaining a high ratio of metal components.

[0043] (Crushing process) Next, the fine powder obtained in the classification step is pulverized to obtain a pulverized product.

[0044] When micro powder is subjected to wet gravity separation without being crushed, the recovery rate of metal components and metal Si may be reduced due to the bonded particles contained in the micro powder. The bonded particles have a lower specific gravity than single metal particles with the same particle size. Therefore, the bonded particles may be separated as light specific gravity powder during wet gravity separation and not recovered as heavy specific gravity powder. In other words, the metal components contained in the bonded particles may not be recovered, resulting in a low recovery rate of the metal components. Even if it is separated as heavy specific gravity powder, metal Si will be mixed into the final concentrate, making it difficult to recover metal Si as a recycle material.

[0045] In this embodiment, by pulverizing the fine powder, the bonded particles are separated into the metal component and the metal Si, and the recovery rate of each can be increased. By pulverizing, the metal Si can be selectively pulverized without excessively finely disintegrating the metal component. In other words, the metal Si of the bonded particles can be pulverized while leaving the metal component intact. This allows the metal Si of the bonded particles to be pulverized and peeled off from the metal component, and the metal component and the metal Si can be separated.

[0046] The resulting pulverized material contains metal particles, metal particles with metallic Si remaining on the surface, metallic Si particles, and trace amounts of glass particles and resin particles.

[0047] As a pulverization method, from the viewpoint of more reliably and selectively pulverizing metal Si, compression pulverization or impact pulverization is preferable. For compression pulverization or impact pulverization, a conventionally known device can be used. For compression pulverization, for example, a disk mill or a roller press device can be used. For impact pulverization, for example, a ball mill can be used.

[0048] The pulverization conditions are not particularly limited as long as the metal Si can be selectively pulverized without excessively pulverizing the metal components. From the viewpoint of recovering the metal components as heavy specific gravity powders at a high recovery rate during the wet specific gravity sorting described below, it is preferable to pulverize the pulverized material so that the particle size is 1 μm or more and 450 μm or less. If the particle size of the particles containing the metal components becomes too small, there is a risk that they will be separated as light specific gravity powders during the wet specific gravity sorting. However, by pulverizing the pulverized material and the particles containing the metal components contained therein so that the particle size falls within the above range, the particles containing the metal components can be more reliably separated as heavy specific gravity powders. In addition, by pulverizing the metal Si particles so that the particle size falls within the above range, the metal Si particles can be more reliably separated as light specific gravity powders. Here, the particle size is a value measured by a laser diffraction / scattering type particle size distribution measuring device or the like.

[0049] In addition, if the force (e.g., impact force or compression force) applied to the crushed material during crushing is excessively large, the metal components may be crushed excessively, and metal Si may not be selectively crushed. In this regard, the crushed material is crushed under conditions such that the 90% passing diameter (so-called D90) of the crushed material is preferably in the range of 75 μm to 450 μm, more preferably in the range of 75 μm to 250 μm. By crushing the material so that D90 is in the above range, the force applied to the crushed material during crushing can be adjusted to an appropriate magnitude, and metal Si can be selectively crushed more reliably while suppressing excessive crushing of the metal components. As a result, the metal components and metal Si can be suitably separated by wet specific gravity separation described later.

[0050] (First gravity sorting process) Next, the pulverized product obtained by the pulverization step is subjected to wet density separation, which is intended to separate particles containing metal components from particles containing other components contained in the pulverized product.

[0051] In this embodiment, a surfactant is used in the wet gravity separation because the pulverized material containing metal Si is difficult to mix with water. Specifically, the pulverized material is mixed with a sorting liquid containing a surfactant to obtain a mixed slurry. By adding the surfactant, the floating of the pulverized material during mixing is suppressed, and the pulverized material is dispersed in the sorting liquid.

[0052] The surfactant used in the sorting liquid is not particularly limited as long as it can be mixed with metal components and metal Si, and known surfactants can be used. For example, linear alkylbenzenes, sodium alkyl ether sulfates, etc. can be used. In addition, the solvent used in the sorting liquid can be, for example, water. In addition, the concentration of the surfactant is not particularly limited as long as the pulverized material can be mixed with water.

[0053] The mixed slurry is then fed to a density separator. As the density separator, a thin flow separator utilizing the difference in particle behavior in a thin flow, a jig separator utilizing the difference in particle sedimentation behavior in a fluid, or a heavy liquid separator can be used. Among these, a thin flow separator is preferred. This is because the thin flow separator can suitably perform density separation even on pulverized materials with small particle sizes.

[0054] Here, the gravity sorting using the thin flow sorter will be specifically described.

[0055] The thin flow separator is provided with a vibrating tray arranged at an angle, and is configured to flow cleaning water onto the vibrating tray. During wet specific gravity sorting, mixed slurry is supplied onto the vibrating tray while flowing cleaning water onto the vibrating tray, and the vibrating tray is vibrated. At this time, light specific gravity powders contained in the mixed slurry are caused to flow below the vibrating tray by the cleaning water, and heavy specific gravity powders are pushed up to the top of the vibrating tray by the vibration, and each particle is separated according to its specific gravity. Specifically, particles with a high ratio of metal components, such as metal particles or particles with metal Si remaining on the surface of metal particles, remain on the vibrating tray as heavy specific gravity powders, and bonded particles with a high ratio of metal Si, metal Si particles, resin particles, glass particles, etc. flow down from the vibrating tray as light specific gravity powders.

[0056] The first heavy specific gravity powder remaining on the vibrating tray is then collected as a concentrate, while the first light specific gravity powder is subjected to a heat treatment process described below.

[0057] The washing water flowing through the thin flow separator preferably contains a surfactant. By using washing water containing a surfactant, it is possible to suppress the floating of the pulverized material during the wet specific gravity separation. This makes it possible to separate the heavy specific gravity powder and the light specific gravity powder more reliably.

[0058] In the thin flow separator, the amplitude width and amplitude speed of the vibrating tray and the supply amount of washing water may be appropriately changed according to the grade and recovery rate of the metal components. The sorting conditions may be appropriately set based on a recovery quality curve that shows the correlation between the grade and recovery rate of the metal components obtained in advance. For example, the amplitude width may be 10 to 110, the amplitude speed may be 60 to 350 rpm (cpm), and the supply amount of washing water may be 0 to 10 L / min.

[0059] As described above, particles containing metal Si and particles containing resin components can be removed from the fine powder obtained through the crushing, classification and pulverization processes, and the particles containing metal components can be separated as the first heavy specific gravity powder. This allows the metal components to be separated from the fine powder with high quality and high recovery rate.

[0060] Specifically, by subjecting micropowder having a metal component Ag content of 1% or less to the above-mentioned treatment, a concentrate having an Ag content of 5% or more can be obtained. Moreover, the Ag contained in the micropowder can be recovered at a recovery rate of 50% or more. Moreover, the metal Si contained in the micropowder can be separated and removed at a rate of 90% or more, and the concentration rate can be increased to 5 times or more. Here, the recovery rate refers to the ratio of the weight of the metal components contained in the finally obtained concentrate divided by the weight of the metal components contained in the raw material (cell mixed powder). Moreover, the concentration rate refers to the ratio of the concentration of the metal components contained in the concentrate divided by the concentration of the metal components contained in the raw material (cell mixed powder).

[0061] (Heat treatment process) Next, the first low specific gravity powder separated in the first specific gravity sorting step is subjected to a heat treatment.

[0062] The first light specific gravity powder contains not only metal Si but also glass. From the viewpoint of reusing metal Si as a silicon source, in this embodiment, metal Si and glass are further separated. However, since metal Si particles and glass particles are hydrophobic due to the adhesion of resin components to their surfaces, if the first light specific gravity powder is subjected to wet specific gravity separation as it is, metal Si particles and the like will aggregate when they come into contact with water, making it difficult to separate them based on the difference in specific gravity.

[0063] Therefore, in this embodiment, the first low specific gravity powder is subjected to a heat treatment before the wet specific gravity separation. The heat treatment can decompose and remove the resin components attached to the surfaces of the metal Si particles and the glass particles. This allows the metal Si particles and the glass particles to regain their inherent hydrophilicity, increase their dispersibility in water, and suppress agglomeration during the wet specific gravity separation. In addition, minute resin components contained in the first low specific gravity powder can also be decomposed and removed.

[0064] The heat treatment conditions here are not particularly limited as long as the resin components attached to the metal Si particles and glass particles can be decomposed and removed. The heating temperature can be appropriately changed depending on the decomposition temperature of the resin components constituting the sealing material 13 and the protective member 14, and for example, the heating temperature is preferably 200°C to 1200°C, more preferably 300°C to 1000°C, and even more preferably 500°C to 800°C. In addition, for example, the heating time is preferably 10 minutes to 5 hours, more preferably 30 minutes to 3 hours, and particularly preferably 1 hour to 2 hours.

[0065] The heat-treated product obtained by heat-treating the first low specific gravity powder contains mainly hydrophilic metal Si particles, glass particles, and the like, from which the resin component has been removed.

[0066] (Second gravity sorting process) The heat-treated product is then subjected to wet density separation, the purpose of which is to separate the metal Si particles and glass particles contained in the heat-treated product.

[0067] The second gravity sorting step may be carried out under the same conditions as the first gravity sorting step. Specifically, the heat-treated material is mixed with a sorting liquid containing a surfactant to obtain a mixed slurry. At this time, the metal Si particles and glass particles can be finely dispersed in the sorting liquid by suppressing aggregation due to their hydrophilicity and the surfactant. By using a surfactant, aggregation can be more reliably suppressed and the particles can be finely dispersed.

[0068] The mixed slurry is then fed to a gravity separator, such as a thin flow separator. Since the metal Si particles and the glass particles have different specific gravities, the difference in specific gravity can be utilized by wet gravity separation to separate one type of particles into a second heavy specific gravity powder and the other type of particles into a second light specific gravity powder.

[0069] The metallic silicon particles separated in the second gravity separation process contain few glass particles and a high proportion of metallic silicon, making it possible to use them directly as a recycled silicon material.

[0070] As described above, according to the recycling method of the present embodiment, first, the solar cell sheet-like structure is crushed, and the crushed material is classified. In the crushed material, each component is crushed to a size according to its material, so that during classification, resin particles can be separated from the crushed material as coarse powder. Next, the fine powder is crushed. As a result, the bonding particles contained in the fine powder are separated into valuable metal components and metal Si. Next, in the first specific gravity sorting step, the crushed product of the fine powder is subjected to wet specific gravity sorting using a sorting liquid containing a surfactant. As a result, the crushed product is dispersed in the sorting liquid, and particles containing metal components are separated as a first heavy specific gravity powder, and metal Si particles, glass particles, etc. are separated as a first light specific gravity powder. Next, the first light specific gravity powder is heat-treated to obtain a heat-treated product. As a result, the resin components attached to the metal Si particles and glass particles are removed, and the hydrophilicity of the metal Si particles and glass particles is restored. Then, in the second sorting step, the heat-treated product is subjected to wet specific gravity sorting. In the heat-treated product, the metal Si particles and the glass particles are both hydrophilic, so that aggregation can be suppressed and they can be finely dispersed in the sorting liquid. This allows the metal Si particles and the glass particles to be sorted based on the difference in specific gravity. In this way, valuable metal components in the solar cell sheet structure can be concentrated, while the metal Si components can be recovered as a recycled material.

[0071] <Other embodiments> Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the gist of the present invention.

[0072] In the above embodiment, the case where the powder is separated into two, heavy specific gravity powder and light specific gravity powder, during wet specific gravity sorting has been described, but the present invention is not limited thereto. For example, during wet specific gravity sorting, the light specific gravity powder washed away by the washing water may be separated in two separate steps with a time interval. During wet specific gravity sorting, particles with lower specific gravity are washed away from the vibrating tray earlier, and particles with heavier specific gravity are washed away later. Therefore, by collecting the light specific gravity powder washed away from the vibrating tray in two separate steps with a time interval, it is possible to collect the powder with a relatively low specific gravity in an earlier time period and the powder with a relatively high specific gravity in a later time period. The light specific gravity powder collected at a time interval includes particles (such as minute metal particles) that contain metal components but are not separated as the heavy specific gravity powder. By collecting this light specific gravity powder together with the heavy specific gravity powder, the recovery rate of the metal components can be increased. Alternatively, the light specific gravity powder may be further subjected to wet specific gravity sorting to collect the heavy specific gravity powder. This allows metal components to be recovered at a high quality and at a higher recovery rate.

[0073] In the above embodiment, the case where the mixed powder is a cell mixed powder obtained from waste of solar cell modules has been described, but the present invention is not limited to this. For example, the mixed powder may be a fine powder obtained by crushing and classifying process scraps generated in the manufacturing process of solar cell modules.

[0074] In addition, when a jig sorter or a heavy liquid sorter is used in the wet gravity sorting process, a sorting liquid containing a surfactant may be added to the pulverized material to form a slurry, and the light specific gravity powder and the heavy specific gravity powder may be separated based on the specific gravity. When water or the like is added during sorting using a jig sorter or a heavy liquid sorter, it is recommended that it be added together with the surfactant. EXAMPLES

[0075] Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0076] Example 1 In this embodiment, the solar cell sheet structure was crushed and the crushed material was subjected to the above-mentioned treatment, thereby separating the components contained in the solar cell sheet structure into individual materials.

[0077] Specifically, first, the solar cell sheet structure was subjected to a shear crushing treatment using a uniaxial cutter mill (model number UIH5-35120MRFX, manufactured by HORAI Co., Ltd.), and 3000 g of crushed material passing through a 50 mm screen was obtained.

[0078] Next, the crushed material was classified by particle size using a vibrating sieve (model number KFO-800-3D, manufactured by Kowa Kogyosho Co., Ltd.), and separated into 2700g of product with a particle size larger than 250μm as coarse powder and 300g of powder with a particle size of 250μm or less as fine powder.Furthermore, the fine powder in the range of 106μm to 250μm was collected as a cell mixed powder.This cell mixed powder weighed 150g, and mainly contained silicon, with an Ag content of 1% or less.

[0079] Next, the cell mixture powder was compressed and pulverized. Specifically, the cell mixture powder was compressed and pulverized using a disk mill (Retsch's "RS200") at a milling rotor speed of 700 rpm for 4 minutes to obtain 150 g of pulverized material. Here, the cell mixture powder was pulverized so that the D90 of the pulverized material was 200 μm or less, and the particle size of the pulverized material was within the range of 9 μm to 394 μm. The particle size of the pulverized material was measured using a laser diffraction / scattering type particle size distribution analyzer "LA-950 V2" manufactured by Horiba, Ltd.

[0080] Next, 150 g of the obtained pulverized material was subjected to wet specific gravity sorting. Specifically, the pulverized material was mixed with a sorting liquid containing water and a surfactant to prepare a mixed slurry. As the surfactant, "Mama Lemon (registered trademark)" manufactured by Lion Corporation was used. Mama Lemon contains 28 volume % of linear alkylbenzene sulfonate, linear alkylbenzene sulfonic acid, and alkyl ether sulfate sodium as surfactants. Next, in a wet specific gravity sorter (Laboratory Mineral Separator), a vibration table (V tray) was installed at an inclination of about 1.75° from the horizontal, and the mixed slurry was then supplied to the V tray. At this time, the V tray was vibrated with an amplitude of 2.5 inches and an amplitude speed of 70 rpm, and washing water was supplied at 0.5 L / min to separate the powders contained in the mixed slurry according to their specific gravity. As the washing water, water containing 0.1 volume % of a surfactant (surfactant concentration 0.028 volume %) was used.

[0081] The heavy specific gravity powder separated from the V-tray within 0.5 minutes after the mixed slurry was supplied was called "Tail 1", the heavy specific gravity powder separated between 0.5 and 2.5 minutes was called "Tail 2", and the light specific gravity powder remaining on the V-tray was called "Conc." and each was collected.

[0082] The recovered Conc., Tail 1 and Tail 2 were each subjected to solid-liquid separation by filtration, and the solids were dried at 105°C to obtain dry powders.

[0083] The composition of the cell mixed powder and each dried powder was analyzed using a handheld XRF analyzer ("Niton XL 3t" manufactured by Thermo Fisher Scientific Co., Ltd.) The grades of each metal are shown in Table 1 below.

[0084] [Table 1]

[0085] Next, 5 g of the low specific gravity powder (Conc.) was heat-treated in an electric muffle furnace (model number FUW232PB, manufactured by ADVANTEC) at 600°C for 1 hour, held at that temperature for 1 hour, and then naturally cooled. The weight of the heat-treated product of the low specific gravity powder was 4.95 g.

[0086] Then, 4.95 g of the obtained heat-treated product was mixed with the above-mentioned sorting liquid, and it was confirmed that the metal Si component and the glass component could be finely dispersed in the sorting liquid while suppressing aggregation. From this, it was confirmed that the metal Si component and the glass component could be separated by the difference in specific gravity by wet specific gravity sorting.

[0087] In this way, valuable metal components, Si metal components, glass components, resin components, etc. were able to be separated and recovered by material from the solar cell module. In particular, valuable metal components such as Ag were recovered at a high concentration rate, and it was confirmed that metallic Si has a high ratio of silicon and can be reused as a recycled material. [Explanation of symbols]

[0088] 1. Solar cell module 10. Solar cell sheet structure 11 Solar Cell 12 Metal Pattern 13 Encapsulating materials 14 Protective materials 15 Glass substrate 16 Frame members

Claims

1. a preparation step of removing a glass substrate and a frame member from a solar cell module to prepare a solar cell sheet-like structure comprising at least solar cells, a metal pattern wired from the solar cells, a sealant for sealing them, a protective member provided on one side of the sealant, and glass residue derived from the glass substrate and remaining on the surface of the sealant; a crushing step of crushing the solar cell sheet structure to form a crushed product; A classification step of classifying the crushed material into fine powder having a small particle size and coarse powder having a large particle size and collecting the fine powder; A grinding step of grinding the fine powder to obtain a ground product; a wet specific gravity sorting step in which the pulverized material is subjected to wet specific gravity sorting using a sorting liquid containing a surfactant to separate the pulverized material into a heavy specific gravity powder and a light specific gravity powder; A heat treatment step of heat treating the low specific gravity powder to obtain a heat-treated product. How to recycle solar modules.

2. The low specific gravity powder contains at least particles containing metal silicon derived from the solar cell and particles containing glass derived from the glass residue. The method for recycling a solar cell module according to claim 1 .

3. When the wet specific gravity sorting step is a first specific gravity sorting step, the method further includes a second specific gravity sorting step of wet specific gravity sorting the heat-treated product using a sorting liquid containing a surfactant after the heat treatment step. The method for recycling the solar cell module according to claim 1 or 2.

4. In the heat treatment step, the heating temperature is 500° C. or more and 800° C. or less. The method for recycling the solar cell module according to claim 1 or 2.

5. In the pulverization step, the micropowder is subjected to compression pulverization or impact pulverization. The method for recycling the solar cell module according to claim 1 or 2.

6. The micropowder includes at least particles containing a metal component, particles containing metal silicon, bonded particles in which the metal component and the metal silicon are bonded, and particles containing glass. The method for recycling the solar cell module according to claim 1 or 2.

7. The particle size of the micropowder is 1 μm or more and 500 μm or less. The method for recycling the solar cell module according to claim 1 or 2.

8. In the pulverization step, the micropowder is pulverized so that the particle size of the pulverized product is 1 μm or more and 450 μm or less. The method for recycling the solar cell module according to claim 1 or 2.

9. In the wet specific gravity separation step, a mixed slurry obtained by mixing the pulverized material and the sorting liquid is supplied to a thin flow sorter, and wet specific gravity separation is performed. The method for recycling the solar cell module according to claim 1 or 2.

10. The mixed slurry to be supplied to the thin flow separator is subjected to wet specific gravity separation while flowing washing water containing a surfactant. The method for recycling a solar cell module according to claim 9.

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