Photoelectric conversion panel material recovery method and material recovery system for photoelectric conversion panels

Abstract

Provided is a novel material recovery method for recovering a material from a photoelectric conversion panel without using an etching solution. This photoelectric conversion panel material recovery method has: a crushing step (S3) for forming a crushed product by crushing a structure which constitutes a photoelectric conversion panel; and a gravity concentration step (S5) for sorting the crushed product on the basis of specific gravity into a first-specific-gravity product which at least has a first specific gravity, and a high-specific-gravity product which has a specific gravity which is higher than is the first specific gravity.

Description

Photoelectric conversion panel material recovery method and photoelectric conversion panel material recovery system

[0001] The present invention relates to a material recovery method and a material recovery system for recovering materials that constitute photovoltaic conversion panels such as solar cell panels.

[0002] In recent years, from the viewpoint of resource utilization and environmental protection, technologies for recycling used materials as resources have become known. For example, photovoltaic conversion modules such as solar cell modules installed on the roofs of buildings such as houses have become increasingly popular in recent years. Therefore, there is a particular demand for the development of recycling technologies for photovoltaic conversion modules.

[0003] Patent Document 1 below discloses a method for recovering metals contained in a battery layer from a battery cell portion of a solar cell module. In Patent Document 1, the metal material constituting the battery layer is dissolved in a nitric acid solution and recovered in a dissolved state in the solution.

[0004] International Publication No. 2019-203026

[0005] In recycling photovoltaic panels, metals are sometimes immersed in an etching solution such as a nitric acid solution to dissolve them, and the eluted metals are then sold. However, the reusability of metals dissolved in an etching solution such as a nitric acid solution can be low.

[0006] Therefore, a new material recovery method and system for recovering materials from photovoltaic conversion panels without using an etching solution is desired.

[0007] A method for recovering materials from a photovoltaic conversion panel according to one embodiment includes a crushing step for forming crushed material by crushing the structure that constitutes the photovoltaic conversion panel, and a specific gravity sorting step for separating the crushed material based on specific gravity into first specific gravity material having at least a first specific gravity and high specific gravity material having a specific gravity greater than the first specific gravity.

[0008] One embodiment of a material recovery system for photovoltaic conversion panels includes a crushing unit that forms crushed material by crushing the structures that make up the photovoltaic conversion panel, and a specific gravity sorting unit that separates the crushed material based on specific gravity into first specific gravity materials having at least a first specific gravity and high specific gravity materials having a specific gravity greater than the first specific gravity.

[0009] FIG. 1 is a schematic cross-sectional view of a photovoltaic conversion module according to one embodiment. FIG. 2 is a schematic enlarged view of a portion of a photovoltaic conversion element according to one embodiment. FIG. 3 is a schematic view of a material recovery system for a photovoltaic conversion panel according to one embodiment. FIG. 4 is a schematic side view of a specific gravity separation unit according to one embodiment. FIG. 5 is a schematic top view of a specific gravity separation unit according to one embodiment. FIG. 6 is a flowchart of a material recovery method for a photovoltaic conversion panel according to one embodiment.

[0010] 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.

[0011] [Configuration of Photovoltaic Conversion Module] 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.

[0012] 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.

[0013] 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.

[0014] 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, a transparent or translucent glass layer. The glass layer may be, for example, tempered glass.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] The photoelectric conversion element 21 is an element that converts light energy into electrical energy. The photoelectric conversion element 21 may have any configuration that is capable of converting light energy into electrical energy. 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 has multiple battery cell units made of a silicon substrate. The battery cell units contain metal materials such as copper and silver as electrode materials and wiring.

[0019] 2 is a schematic enlarged view of a portion of a photoelectric conversion element according to one embodiment. Fig. 2 shows a portion of a photoelectric conversion element having so-called crystalline silicon. This photoelectric conversion element 21 has a back electrode layer 21a, a silicon crystal layer 21b, an anti-reflection film 21c, and an electrode 21d. The silicon crystal layer 21b may include an n-type layer or a p-type layer.

[0020] The anti-reflection film 21c is provided on the surface side of the silicon crystal layer 21b. The anti-reflection film 21c is made of, for example, SiO ２ , SiN, and / or TiO ２ The electrode 21d is disposed on the front surface side of the anti-reflection film 21c. The electrode 21d may contain, for example, silver.

[0021] [Materials Recovery System] A materials recovery system according to one embodiment will be described with reference to Figs. 3 to 5. Fig. 3 is a schematic diagram of a materials recovery system for photovoltaic conversion panels according to one embodiment. Fig. 4 is a schematic side view of a gravity separation unit according to one embodiment. Fig. 5 is a schematic top view of a gravity separation unit according to one embodiment.

[0022] The material recovery system 100 for photovoltaic conversion panels can be used as a system for recovering materials from the above-described photovoltaic conversion panels 20. Preferably, the material recovery system 100 may be a system for recovering materials from the photovoltaic conversion panels 20 that contain silicon (including silicon compounds; the same applies below). The material recovery system 100 may process a structure obtained by removing a glass layer, such as a cover glass, from the photovoltaic conversion panels 20, for example.

[0023] The material recovery system 100 may include a crushing unit 110 , an air separation unit 120 , a gravity separation unit 130 and a drying unit 140 .

[0024] The crushing unit 110 may have any structure as long as it is capable of crushing the structure that constitutes the photovoltaic conversion panel 20. The crushing unit 110 crushes the structure that constitutes the photovoltaic conversion panel to form crushed material. The crushing unit 110 may preferably crush the structure that constitutes the photovoltaic conversion panel until it becomes small particles. The structure that constitutes the photovoltaic conversion panel 20 to be crushed may be the photovoltaic conversion panel 20 itself, or may be a structure obtained by removing the glass layer from the photovoltaic conversion panel 20.

[0025] The crushing unit 110 may include a first crushing unit 112 and a second crushing unit 115. The first crushing unit 112 may be, for example, a single-shaft crusher having bit-like blades on a rotating shaft that continuously crushes structures while biting into them with fixed blades, a biaxial crusher that sandwiches the workpieces between rotating blades and generates high shear stress, or a vertical crusher that continuously crushes the workpieces by hitting them with a high-speed rotating hammer until they are reduced to a desired size or smaller. Preferably, the first crushing unit 112 may be a single-shaft crusher with bit-like crushing teeth that is superior in shape control of the workpieces compared to the second crushing unit 115 located further downstream and does not shear or crush the structures.

[0026] The second crushing unit 115 may be, for example, a single-shaft crusher that cuts the workpieces using a wide rotary blade and a fixed blade, or a shredder-type double-shaft crusher. The second crushing unit 115 may be configured to crush the workpieces crushed by the first crushing unit 112 into smaller particles. Preferably, the second crushing unit 115 is a single-shaft crusher that cuts the workpieces using a wide rotary blade and a fixed blade. This makes it possible to more efficiently peel off the first sealing layer 24 and the second sealing layer 25 from the photoelectric conversion element 21, and to separate and crush the anti-reflection film 21c and the silicon crystal layer 21b of the photoelectric conversion element 21, when the photoelectric conversion panel includes a photoelectric conversion element having crystalline silicon.

[0027] The second crushing unit 115 may also be, for example, a mortar-shaped crusher having opposing, rotatable upper and / or lower disk-shaped plates. In this case, shear stress can be applied to the workpiece by sandwiching the workpiece between the rotating upper and lower plates and applying a mechanical force to the workpiece. This makes it possible to more efficiently peel off the first sealing layer 24 and the second sealing layer 25 from the photoelectric conversion element 21, and to separate and crush the anti-reflection film 21c and the silicon crystal layer 21b of the photoelectric conversion element 21.

[0028] In the illustrated configuration, the crushing unit 110 includes a first crushing unit 112 and a second crushing unit 115. Alternatively, if possible, the crushing unit 110 may include only one of the first crushing unit 112 and the second crushing unit 115. Furthermore, the crushing unit 110 may include three or more types of crushing units.

[0029] The air separation unit 120 may include a storage space 122 and an air generator 124. Preferably, the air separation unit 120 may be a cyclone-type air separator that generates a vortex wind within the storage space 122. The cyclone-type air separator may be configured to separate small-sized material from the crushed material crushed by the crushing unit 110.

[0030] The air sorting unit 120 separates the crushed material crushed by the crushing unit 110 using wind force based on the weight and volume of the materials in the crushed material. Preferably, the air sorting unit 120 separates the crushed material crushed by the crushing unit 110 into a first material group having a relatively large particle size and specific gravity and a second material group having a relatively small particle size (powder state) using wind force. Specifically, the first material group consists of the crushed material that was not blown by the desired wind force. On the other hand, the second material group consists of the crushed material that was blown by the desired wind force. Here, the first material group is a material group that will be used in the specific gravity separation unit described below, and the second material group is a material group that will not be used in the specific gravity separation unit.

[0031] The air sorting unit 120 sorts the crushed material primarily based on weight and volume. Therefore, it is possible to recover relatively light and small-volume materials from the photovoltaic panels. Therefore, in the case of silicon-based photovoltaic panels, the second material group sorted by the air sorting unit 120 may primarily include powdered silicon and encapsulant from the crushed material.

[0032] The air separation unit 120 may be located between the crushing unit 110 and the gravity separation unit 130. The crushed material crushed by the crushing unit 110 is carried into the storage space 122 by wind generated by a wind generator 124. A first group of materials that is not blown by the desired wind force is sent to the gravity separation unit 130 through an outlet 123 located at the bottom of the storage space 122. A second group of materials that is blown by the wind force is sent from above the storage space 122 to a second storage space 125 located downstream, and is collected as needed from an outlet 126 located at the bottom of the second storage space 125.

[0033] The air sorting unit 120 may also have an exhaust port 129 that communicates with the second storage space 125 from above.

[0034] The gravity separation unit 130 may include a vibrable stage 132, a motor (not shown) that vibrates the stage 132, and an ejection port 138 that ejects a liquid. In this embodiment, the stage 132 is tilted in one direction. The ejection port 138 ejects a liquid for separating materials in the crushed material based on differences in sedimentation behavior. The liquid may be, for example, water. The ejection port 138 is positioned on the tilted stage at a position that allows the liquid to be ejected.

[0035] Preferably, a first passage 133 and a second passage 134 are formed on the stage 132. A partition 135 is formed between the first passage 133 and the second passage 134. The first passage 133 and the second passage 134 communicate with each other downstream of the partition 135. In this case, the injection port 138 is preferably positioned so as to generate a relatively strong flow of liquid in the first passage 133 of the inclined stage 132.

[0036] In this embodiment, a weir 136 is provided in the lower portion of the stage 132 across the width direction of the stage 132 to partially block the flow of liquid on the stage 132. The weir 136 can form a puddle 139 on the stage 132.

[0037] A motor (not shown) vibrates the stage 132 so as to bounce the crushed materials on the stage 132, specifically those with a relatively high specific gravity, upstream. The amplitude of the vibration applied to the stage 132 may be set as appropriate.

[0038] The first material group sent from the air separation unit 120 is released onto a stage 132 of the gravity separation unit 130, specifically near the downstream portion of the first passage 133 (region R1 in FIG. 5 ). If the air separation unit 120 is not provided, all of the crushed material crushed by the crushing unit 110 may be sent to the gravity separation unit 130. The gravity separation unit 130 separates the crushed material crushed by the crushing unit 110 into first specific gravity materials having at least a first specific gravity and high specific gravity materials having a specific gravity greater than the first specific gravity, based on specific gravity. More preferably, the gravity separation unit 130 may be configured to separate the crushed material into first specific gravity materials having a first specific gravity, second specific gravity materials having a second specific gravity greater than the first specific gravity, and third specific gravity materials having a third specific gravity greater than the second specific gravity.

[0039] The injection port 138 injects liquid onto the stage 132 during operation of the gravity separation unit 130. This flow of liquid causes particles with a relatively low specific gravity to flow downward and reach a pool 139 formed by the weir 136.

[0040] The third specific gravity materials, which have a relatively high specific gravity among the high specific gravity materials, are slightly bounced up by the vibration of the stage 132 and move upward through the first passage 133 of the stage 132 (see arrow A). The third specific gravity materials are discharged from an outlet above the stage 132 into the drying unit 140 and dried in the drying unit 140.

[0041] Of the high specific gravity materials, the second specific gravity materials, which have a relatively low specific gravity, sink in the puddle 139 and continue to increase near the top of the puddle 139 due to the action of the liquid flow and the vibration of the stage 132. As the second specific gravity materials increase, they begin to move upward on the stage 132 from areas where the liquid flow is weak due to the action of the vibration of the stage 132. Here, because almost no liquid from the injection port 138 flows through the second passage 134, the second specific gravity materials move upward through the second passage 134 (see arrow B). This allows the second specific gravity materials to be recovered separately from the third specific gravity materials.

[0042] In this way, by vibrating the stage 132 with the crushed material placed on it, the high specific gravity material can be separated into second specific gravity material having a second specific gravity greater than the first specific gravity and third specific gravity material having a third specific gravity greater than the second specific gravity by the vibration of the stage on which the crushed material is placed. Furthermore, as will be described later, the stage 132 can separate the material in the crushed material into the first specific gravity group, second specific gravity material, and third specific gravity material by the vibration of the stage and the action of the liquid.

[0043] A second weir (not shown) extending across a width approximately equal to the width of the first passage 133 may be formed near the downstream end of the partition 135. This second weir may be lower than the weir 136 described above. In this case, even if the third specific gravity substance flows downstream of the stage 132, it is blocked by the second weir and is therefore less likely to enter the second passage 134. Therefore, the third specific gravity substance is more likely to move upward through the first passage 133 without entering the second passage 134. Furthermore, the second specific gravity substance may climb over the lower second weir and reach the weir 136, but while being blocked by the weir 136, it is more likely to move toward the widthwise end of the stage 132, i.e., toward the second passage 134. This allows the second specific gravity substance to move upward through the second passage 134 from the widthwise end of the stage 132. Therefore, when the second weir is provided, the accuracy of separating the second specific gravity materials from the third specific gravity materials may be improved.

[0044] The first specific gravity substances float on the upper surface of the puddle 139. The first specific gravity substances floating on the upper surface of the puddle 139, together with the flow of the liquid, go over the weir 136 and the second weir described above, and are discharged from the lower end of the stage 132 (see arrow C). This allows the first specific gravity substances to be collected separately from the higher specific gravity substances (the second specific gravity substances and the third specific gravity substances).

[0045] In the above embodiment, the gravity separation unit 130 is configured to simultaneously separate materials of the first specific gravity, materials of the second specific gravity, and materials of the third specific gravity. Alternatively, the gravity separation unit 130 may have a separate unit for separating materials of the first specific gravity from materials of high specific gravity and a separate unit for separating materials of high specific gravity into materials of second specific gravity and materials of third specific gravity. In this case, the unit for separating materials of the first specific gravity from materials of high specific gravity may be, for example, a wet gravity separation unit based on differences in sedimentation behavior in a liquid such as water. The unit for separating materials of high specific gravity into materials of second specific gravity and materials of third specific gravity is not particularly limited and may be a wet separation unit or, for example, a dry separation unit using stage vibration.

[0046] The drying unit 140 may be configured to dry the material separated by the gravity separation unit 130. In the illustrated embodiment, the drying unit 140 is configured to dry the third gravity material recovered through the gravity separation unit 130. Additionally or alternatively, a drying unit may be provided to dry the first gravity material and / or the second gravity material.

[0047] [Materials Recovery Method] Next, a method for recovering materials from a photovoltaic conversion panel according to one embodiment will be described with reference to Figures 3 to 6. Figures 3 to 5 have been described above. Figure 6 is a flowchart of a method for recovering materials from a photovoltaic conversion panel according to one embodiment.

[0048] First, the photovoltaic conversion module 10 described above is prepared. The photovoltaic conversion panel 20 constituting the photovoltaic conversion module 10 is preferably a panel containing silicon. Then, the frame 30, a junction box (not shown), and the like are removed from the photovoltaic conversion module 10 (step S1). This allows the photovoltaic conversion panel 20 to be removed.

[0049] Next, the cover glass (glass layer) 23 is removed from the photovoltaic conversion panel 20 (step S2). The cover glass 23 is separated from the photovoltaic conversion panel 20 by peeling it off. The separated cover glass 23 can be recycled as glass cullet raw material.

[0050] If necessary, the rear protective layer 22 may be separated from the photovoltaic conversion panel 20. In this case, the rear protective layer 22 can be recycled in the form of a sheet. Note that the subsequent steps may be performed without separating the rear protective layer 22.

[0051] In step S2, a structure is obtained in which the cover glass 23, or the cover glass 23 and the rear protective layer 22, are removed from the photovoltaic conversion panel 20.

[0052] Next, the photoelectric conversion panel 20, specifically the structure that has been subjected to step S2, is crushed (step S3). The method for crushing the structure is not particularly limited. The structure is crushed, for example, by the crushing unit 110 described above. The crushed material formed by crushing the structure may include metal materials such as copper and silver, silicon, resin materials, etc.

[0053] In step S3, as described above, the structure may be crushed and / or pulverized in two stages using both the first crushing unit 112 and the second crushing unit 115. In other words, step S3 may include both a first crushing step and a second crushing step. The first crushing step is performed, for example, by the first crushing unit 112 described above.

[0054] In the second crushing step, the structure crushed by the first crushing unit 112 is further crushed. When the photoelectric conversion panel includes photoelectric conversion elements having crystalline silicon, the second crushing step preferably involves peeling the second sealing layer 25 constituting the photoelectric conversion panel from the photoelectric conversion elements 21. The peeling method is not particularly limited. Crushing of the structure is performed, for example, by the second crushing unit 115 described above. In this second crushing step, the photoelectric conversion elements 21 peeled from the second sealing layer 25 become crushed material containing powder-like particles containing a large proportion of the surface layer (the anti-reflection film 21c and the electrode 21d) and large particles containing a large proportion of the element body portion (the back electrode layer 21a and the silicon crystal layer 21b). In other words, the silicon is separated into powder-like particles having a small particle size and particles having a larger particle size than the powder-like particles.

[0055] When the photoelectric conversion panel includes a photoelectric conversion element having crystalline silicon, the silicon is easily separated into powder-like particles having a small particle size and particles having a particle size larger than the powder-like particles. ２ The bending strength of SiN and SiN is approximately one-third that of silicon. Furthermore, the thermal expansion coefficients of these materials used in the anti-reflection coating 21c are approximately one-tenth that of silicon. Therefore, the anti-reflection coating 21c is subjected to a large stress, and its brittleness is considered to be extremely low compared to silicon. Based on this, the inventors discovered that when mechanical pressure, i.e., a crushing process, is applied, the anti-reflection coating 21c formed on silicon and the electrode 21d formed thereon tend to peel off as powder-like particles with small particle sizes. As a result, a material with an intermediate specific gravity (a material with the same or similar specific gravity as the second specific gravity material), in this case silicon, is crushed into powder-like particles with mainly small particle sizes and particles with particle sizes larger than the powder.

[0056] Next, an air sorting step S4 is performed as necessary. The air used in the air sorting step S4 may be a vortex wind. In the air sorting step S4, the crushed material formed by crushing the structure is separated by air force into a first material group to be used in the specific gravity sorting step S5 described below and a second material group not to be used in the specific gravity sorting step S5. The crushed material is separated by air force based on the weight and volume of the material in the crushed material. Specifically, in the air sorting step S4, the crushed material is separated by air force based on the weight and volume of the material in the crushed material. The first material group includes materials with a relatively large particle size and specific gravity, and the second material group includes particles with a relatively small particle size (in a powder state).

[0057] If the photovoltaic panel includes a photovoltaic element having crystalline silicon, in step S3, a material having an intermediate specific gravity (a material having the same or similar specific gravity as the second specific gravity material), in this case silicon, is crushed into powder-like particles having a small particle size and particles having a particle size larger than the powder. In the air sorting step S4, these powder-like particles having a small particle size, i.e., powder-like silicon particles, can be collected as the second material group. In this case, it is preferable to adjust the strength of the wind force in the air sorting step S4 so that the material having an intermediate specific gravity, in this case silicon, is collected as the second material group.

[0058] Next, a gravity sorting step S5 is performed to separate the crushed material. In the gravity sorting step S5, the crushed material is separated based on specific gravity into first specific gravity materials having at least a first specific gravity and high specific gravity materials having a specific gravity greater than the first specific gravity. Preferably, the gravity sorting step separates the crushed material into first specific gravity materials, second specific gravity materials having a second specific gravity greater than the first specific gravity, and third specific gravity materials having a third specific gravity greater than the second specific gravity. As described above, this separation based on specific gravity can be performed based on at least one, preferably both, of the difference in sedimentation behavior of materials in the crushed material in a liquid and vibration of a stage carrying the crushed material. Preferably, the gravity sorting step S5 includes separating the crushed material into first specific gravity materials, second specific gravity materials, and third specific gravity materials by vibrating an inclined stage carrying the crushed material while flowing a liquid through the stage, as described with reference to Figures 4 and 5.

[0059] Next, if necessary, the materials separated by the gravity separation unit, i.e., the first specific gravity material, the second specific gravity material, and / or the third specific gravity material, are dried (step S6). In this embodiment, the third specific gravity material is dried by the drying unit 140. Additionally, the first specific gravity material and / or the second specific gravity material may also be dried if necessary.

[0060] In the case of a silicon-based photovoltaic panel 20, the photovoltaic panel 20 often contains silicon, metal materials such as copper and silver, and resin materials. In this case, the third specific gravity material mainly contains metal materials such as copper. Copper has a higher specific gravity than other materials, so it can be selectively separated into the third specific gravity material. Therefore, the above-mentioned material recovery method can achieve high recovery efficiency for copper. The second specific gravity material mainly contains silicon particles. Silicon has a lower specific gravity than copper, so it is easily contained in the second specific gravity material. Therefore, the above-mentioned material recovery method can also be suitable for recovering and recycling silicon particles. The first specific gravity material mainly contains a large amount of resin materials.

[0061] As mentioned above, the inventors of the present application discovered that when a photoelectric conversion panel includes photoelectric conversion elements having crystalline silicon, the second material group sorted in the air sorting step S4 contains a large amount of powdered silicon generated during the crushing step S3, and that this powdered silicon is primarily pulverized material from the surface layer of the photoelectric conversion elements 21 (the anti-reflection coating 21c and the electrode 21d). Because the electrode 21d located on the surface layer of the photoelectric conversion elements 21 contains silver, the powdered silicon and silver are mixed together. On the other hand, silicon with a larger particle size than the powdered silicon is believed to be primarily derived from the silicon crystal layer 21b, and therefore the amount of silver contained in the larger particle size silicon is believed to be relatively low. In the above embodiment, powdered silicon with a relatively high silver content can be recovered separately from larger particle size silicon with a relatively low silver content by the air sorting step S4. This enables efficient separation and recovery of silicon.

[0062] The powdered silicon sorted in the air sorting step S4 contains a small amount of organic matter pulverized into powder. Therefore, the powdered silicon (second material group) may be subjected to gravity separation or sieving as necessary. This makes it possible to remove organic matter from the powdered silicon in the second material group.

[0063] According to the above-described material recovery method, materials such as copper and silicon can be recovered in a solid state without using an etching solution such as nitric acid. Furthermore, the gravity separation step S5 also makes it possible to separately recover metal materials such as copper, silicon, and resin materials. In particular, by combining the air separation step S4 and the gravity separation step S5, metal materials such as copper can be separated at a high purity.

[0064] The second material group recovered in the air sorting step S4 may contain the same material as the material primarily contained in the second specific gravity material separated in the gravity sorting step S5, but in a smaller particle size than the material primarily contained in the second specific gravity material. If the photovoltaic conversion panel includes a photovoltaic conversion element having crystalline silicon, the material corresponds to silicon. In this way, by additionally using the air sorting step S4 in addition to gravity sorting, small-particle powder-like materials can be individually recovered. Note that this is not limited to cases where the photovoltaic conversion panel is crystalline silicon, but can also be applied when the same material is pulverized into pulverized particles of different particle sizes.

[0065] [Example] Materials were recovered from a photovoltaic conversion panel 20 using the above-described material recovery system and material recovery method. In this example, materials were recovered from a silicon-based solar cell panel, specifically, a structure obtained by removing the cover glass 23 and rear protective layer 22 from the solar cell panel, using the system shown in Figures 3 to 5. Specifically, the crushed material was separated into the second material group, first specific gravity materials, second specific gravity materials, and third specific gravity materials through the air sorting step S4 and the gravity sorting step S5. In the gravity sorting step S5, the inclination of the stage 132 was 4°, and the vibration frequency of the stage 132 was 49 Hz.

[0066] The results of measuring the copper, silver, silicon, and lead contents in the second material group, the second specific gravity material, and the third specific gravity material are shown in Table 1 below. (Table 1)

[0067] The results shown in Table 1 indicate that the second material group mainly contains silicon and resin materials. The silicon contained in the second material group was in the form of powdered fine particles. Because the powdered silicon has a large difference in specific gravity from the mixed resin material, it could be easily separated by gravity separation or sieving if necessary.

[0068] The first specific gravity materials separated in the gravity separation step S5 mainly contained resin materials. The first specific gravity materials can be recycled by mixing them with asphalt or concrete. Note that, since the proportion of silicon and metal materials contained in the first specific gravity materials is small, it can be seen that silicon and metal materials can be recovered in a separate group with a relatively high purity.

[0069] The second specific gravity material separated in the gravity separation step S5 mainly contains silicon. The resin material contained in the second specific gravity material is less than 1%, and the ratio of silicon contained in the second specific gravity material is more than 90%. In this way, silicon with a relatively large particle size can be recovered with high purity.

[0070] Furthermore, the third specific gravity matter separated in the gravity separation step S5 mainly contained copper. The proportion of resin material contained in the third specific gravity matter was below the measurement limit (almost 0%). Therefore, it was found that it was possible to recover copper with high purity.

[0071] Silicon is contained in large amounts in both the second material group and the second specific gravity material. However, the average particle size of the silicon contained in the second material group is smaller than the average particle size of the silicon contained in the second specific gravity material. In this way, the material recovery method of the present invention can separately recover silicon with different average particle sizes.

[0072] The results of measuring whether the silver contained in the photovoltaic conversion panel 20 was sorted into the second material group, the first specific gravity material, the second specific gravity material, or the third specific gravity material are shown in Table 2 below. (Table 2)

[0073] The results shown in Table 2 indicate that silver is primarily contained in the second material group and the second specific gravity material, which are suitable for refining. The amount of silver contained in the second material group and the second specific gravity material was 95.45% of the total amount of silver. Here, approximately 80% of silver can be recovered by etching with nitric acid after immersion for 5 minutes. Therefore, it can be seen that the material recovery method of the present invention can recover silver at a higher yield than etching using nitric acid.

[0074] 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.

[0075] This application claims priority based on Japanese Patent Application No. 2022-011587, filed on January 28, 2022, the entire contents of which are incorporated herein by reference.

Claims

1. A crushing step of forming crushed materials by crushing a structure constituting a photoelectric conversion panel; A specific gravity sorting step of sorting the crushed materials into a first specific gravity material having at least a first specific gravity and a high specific gravity material having a specific gravity greater than the first specific gravity, based on the specific gravity. A method for recovering materials of a photoelectric conversion panel having the above steps.

2. The specific gravity sorting step includes sorting the crushed materials into a first specific gravity material, a second specific gravity material having a second specific gravity greater than the first specific gravity, and a third specific gravity material having a third specific gravity greater than the second specific gravity. The method for recovering materials of a photoelectric conversion panel according to Claim 1.

3. The specific gravity sorting step includes sorting the crushed materials based on at least one of the difference in sedimentation behavior of the materials in the crushed materials in a liquid and the vibration of a stage on which the crushed materials are placed. The method for recovering materials of a photoelectric conversion panel according to Claim 1.

4. The method for recovering materials of a photoelectric conversion panel according to Claim 1 includes a wind force sorting step of separating the crushed materials into a first material group used in the specific gravity sorting step and a second material group that is lighter than the first material group and not used in the specific gravity sorting step, by wind force.

5. The method for recovering materials of a photoelectric conversion panel according to Claim 1 includes a wind force sorting step of separating the crushed materials into a first material group used in the specific gravity sorting step and a second material group that is lighter than the first material group and not used in the specific gravity sorting step, by wind force. The second material group is the same material as the material mainly contained in the second specific gravity material and includes a material in a smaller particle form than the material mainly contained in the second specific gravity material. The method for recovering materials of a photoelectric conversion panel according to Claim 2.

6. The photoelectric conversion panel includes at least a metal containing copper, silicon, and resin. The second specific gravity material mainly contains silicon. The third specific gravity material mainly contains copper. The method for recovering materials of a photoelectric conversion panel according to Claim 2.

7. The method for recovering materials of a photoelectric conversion panel according to Claim 1 further includes a step of removing a glass layer from the photoelectric conversion panel before the crushing step.

8. A crushing unit that forms crushed materials by crushing a structure constituting a photoelectric conversion panel; A specific gravity sorting unit that sorts the crushed materials into a first specific gravity material having at least a first specific gravity and a high specific gravity material having a specific gravity greater than the first specific gravity, based on the specific gravity. A material recovery system for a photoelectric conversion panel having the above units.

9. The specific gravity separation unit is configured to separate the crushed material into a first specific gravity material, a second specific gravity material having a second specific gravity greater than the first specific gravity, and a third specific gravity material having a third specific gravity greater than the second specific gravity. The material recovery system for a photoelectric conversion panel according to claim 8.

10. The specific gravity separation unit includes an injection port for injecting a liquid for separating materials in the crushed material based on differences in sedimentation behavior. The material recovery system for a photoelectric conversion panel according to claim 8.

11. The material recovery system for a photoelectric conversion panel according to claim 8 includes a wind force separation unit that separates the crushed material into a first material group used in the specific gravity separation unit and a second material group that is lighter than the first material group and not used in the specific gravity separation unit by wind force.

12. The wind force separation unit includes a cyclone type wind force separator that separates small-grained materials from the crushed material. The material recovery system for a photoelectric conversion panel according to claim 11.

13. The material recovery system for a photoelectric conversion panel according to claim 9 has a vibratable stage for separating the materials in the crushed material into the first specific gravity material, the second specific gravity material, and the third specific gravity material.

14. The material recovery system for a photoelectric conversion panel according to claim 8 has a drying unit for drying the materials separated by the specific gravity separation unit.