Silicon recovery method from solar cell module

Abstract

To provide a silicon recovery method from solar cell module that can recover silicon from a solar cell module without any cost and effort.SOLUTION: A silicon recovery method comprises: a step S2 at which an outer frame member and a glass substrate are removed, and a solar cell module, which has at least a solar battery cell containing silicon, a resin-made encapsulation material for encapsulating around the solar battery cell, and a resin-made protective sheet for covering the encapsulation material on a rear face side of the solar battery cell is cut; a step S4 at which the solar cell module is crushed by an impact type crusher having a crushing container into which the cut solar cell module is inputted, and rotor for stirring an inputted material in the crushing container; and a step S5 at which silicon is separated from a crushed material crushed by the impact type crusher by screening, and is recovered.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for recovering silicon from a solar cell module. [Background technology]

[0002] Generally, a solar panel used for solar power generation is formed by fitting a solar cell module, the surface of which is covered with a glass substrate, into an outer frame member made of aluminum, etc. Here, the solar cell module has a solar cell containing silicon, a resin sealing material that seals the periphery of the solar cell, and a resin protective sheet that covers the sealing material on the back side of the solar cell.

[0003] Known techniques for recovering silicon, a valuable resource, from solar cell modules include, for example, removing the outer frame member, then using a heated cutter to separate the glass substrate and protective sheet, and then removing the encapsulant from the solar cell using a solubilization method in which the encapsulant is chemically dissolved using a chemical solution, and then immersing the remaining portion in molten tin to recover the silicon floating on top of the molten tin (see, for example, Patent Document 1).

[0004] Also known is a technique in which a solar panel with its outer frame removed is immersed in an aromatic organic solvent, and ultrasonic waves are applied to the solar panel in the aromatic organic solvent to separate the solar cell, the sealant, and the glass substrate, and silicon is recovered from the organic solvent (see, for example, Patent Document 2).

[0005] Furthermore, a technique is known in which high-pressure water is jet-sprayed onto a solar panel to crush the solar cell module including the solar cells, leaving only the glass substrate (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-34087 A [Patent Document 2] JP 2012-19134 A [Patent Document 3] Patent No. 7022467 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the silicon recovery method disclosed in Patent Document 1 requires high-temperature treatment to melt tin, which results in high energy costs. The silicon recovery method disclosed in Patent Document 2 requires a long ultrasonic immersion treatment, which is not suitable for large-scale recovery of silicon. In addition, the method uses a volatile organic solvent, which results in a large environmental load. Furthermore, the method disclosed in Patent Document 3 makes it possible to separate a solar cell module containing solar cells from a glass substrate, but does not specify a method for separating and recovering silicon contained in the solar cells.

[0008] The present invention has been made in light of the above-mentioned problems, and aims to provide a method for recovering silicon from solar cell modules, which can recover silicon from solar cell modules without incurring costs or effort. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the method for recovering silicon from a solar cell module of the present invention includes a first step of cutting a solar cell module from which an outer frame member and a glass substrate have been removed, the solar cell module having at least solar cells containing silicon, a resin sealing material that seals the periphery of the solar cell, and a resin protective sheet that covers the sealing material on the back side of the solar cell; a second step of crushing the solar cell module using a crusher that has a crushing container into which the cut solar cell module is placed and a rotor that stirs the material placed in the crushing container; and a third step of separating and recovering the silicon from the material crushed by the crusher by sieving or air classification. Effect of the Invention

[0010] As a result, the method for recovering silicon from a solar cell module of the present invention makes it possible to recover silicon from the solar cell module without incurring additional costs or labor. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a schematic structure of a solar panel according to a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view showing a schematic structure of a solar cell module according to a first embodiment. [Diagram 3] 1 is a flowchart showing the steps of a silicon recovery method according to a first embodiment. [Figure 4] FIG. 2 is an explanatory diagram showing an example of a solar cell module piece. [Diagram 5] FIG. 1 is an explanatory diagram showing a configuration of an impact crusher used in the silicon recovery method of Example 1. [Figure 6] FIG. 1 is an explanatory diagram showing a configuration of an air current type crusher used in the silicon recovery method of Example 1. [Figure 7] FIG. 2 is an explanatory diagram showing the material collected on a sieve with an opening of 0.8 mm after pulverization using an airflow pulverizer. [Figure 8] FIG. 2 is an explanatory diagram showing the material that falls through a sieve with an opening of 0.8 mm after pulverization using an airflow pulverizer. [Figure 9] These are the experimental results showing the relationship between the mixing time in an impact crusher and the amount of crushed material recovered under the sieve for each circumferential speed of the rotor. [Figure 10] 1 shows the results of an experiment showing the relationship between the peripheral speed of the rotor of an impact crusher and the amount and rate of silicon recovered. [Figure 11] 1 shows the results of an experiment showing the relationship between the peripheral speed of the rotor of an airflow mill and the amount and rate of silicon recovered. [Figure 12] 1 is a table showing the analysis results of the undersize recovered material and the silicon recovery results after pulverization using an impact pulverizer, an airflow pulverizer, a pin mill, a hammer mill, and a ball mill. [Figure 13]1 is a table showing the measurement results of the area and mass of a solar cell module piece and the calculation results of the mass per unit area of ​​the solar cell module piece. [Figure 14] FIG. 2 is an explanatory diagram showing a micrograph image of a cross section of a solar cell module piece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the method for recovering silicon from a solar cell module according to the present invention will be described below based on Example 1 shown in the drawings.

[0013] The solar cell module 10 of the first embodiment is a component of a solar panel 1 that converts light energy such as sunlight into electrical energy. Here, as shown in Fig. 1, the solar cell panel 1 is formed by fitting a solar cell module 10, the surface of which is covered with a glass substrate 2, into an outer frame member 3 made of aluminum or the like.

[0014] As shown in FIG. 2, the solar cell module 10 has a plurality of solar cells 11 in the form of a sheet (panel), a metal pattern 12 wired from the solar cells 11, a sealing material 13 that seals the periphery of the solar cells 11, and a protective sheet 14 that covers the sealing material 13 that seals the back side of the solar cells 11.

[0015] The solar cell 11 is formed of a semiconductor containing silicon, such as single crystal silicon, polycrystalline silicon, or amorphous silicon. The crystalline silicon used in the solar cell 11 has a high purity and can be widely reused if it can be recovered. For example, silicon recovered from the solar cell module 10 can be nitrided to form silicon nitride, which can be used for hard insulating bearing materials and tools. Silicon recovered from the solar cell module 10 can be oxidized to form silica, which can be reused as a sealant resin filler. Furthermore, high-purity hydrogen gas can be extracted by mechanochemically treating the silicon recovered from the solar cell module 10.

[0016] The metal pattern 12 has surface electrodes provided on the surfaces of the solar cells 11 and bus bar electrodes that electrically connect the multiple solar cells 11. The metal pattern 12 is made of, for example, copper or silver.

[0017] The sealing material 13 is formed of a resin such as ethylene vinyl acetate copolymer resin (EVA) or polyethylene (PE). The sealing material 13 is filled around the solar cell 11 including its front and back surfaces, and is integrated with the solar cell 11 and the metal pattern 12 to form a sheet (panel). The sealing material 13 is bonded to the solar cell 11, the glass substrate 2, and the protective sheet 14 by heating and pressurizing. Since the sealing material 13 is required to have performance such as transparency, flexibility, adhesiveness, tensile strength, and weather resistance, various additives are generally blended therein.

[0018] The protective sheet 14 is formed of a resin such as polyvinyl fluoride (PVF), polyethylene terephthalate (PET), or polyethylene (PE). Since the protective sheet 14 is exposed to the outside air, it is desirable for the protective sheet 14 to have properties such as weather resistance (UV light resistance, moisture resistance, heat resistance, salt damage resistance, etc.), water vapor barrier properties, electrical insulation, mechanical properties (tensile strength, elongation, tear strength, etc.), and chemical resistance. In addition, since the protective sheet 14 is required to have properties such as adhesion to the sealing material 13, it may be formed by laminating multiple film sheets having different properties.

[0019] Furthermore, the sealing material 13 and the protective sheet 14 are both more flexible than the solar cell 11, which contains silicon. That is, the solar cell 11 is harder and more brittle than the sealing material 13 and the protective sheet 14.

[0020] Next, the procedure of the method for recovering silicon from the solar cell module 10 of the first embodiment will be described with reference to the flow chart shown in FIG.

[0021] In step S1, a recovery preparation process is performed in which the glass substrate 2 and outer frame member 3 are removed from the solar panel 1 and the solar cell module 10 is taken out, and then the process proceeds to step S2. Note that the method for removing the glass substrate 2 and outer frame member 3 from the solar panel 1 is not particularly limited. That is, the glass substrate 2 is removed by, for example, a hot knife method, a roll crushing method, or a shot blasting method. In addition, in the recovery preparation process, it is desirable to also remove as much of the wiring (metal pattern 12) provided on the solar panel 1 as possible.

[0022] In step S2 (first step), following the implementation of the collection preparation process in step S1, the solar cell module 10 is cut into pieces of a size that can be fed into a crusher (such as the impact crusher 100 or the airflow crusher 200) described below, and the process proceeds to step S3. FIG. 4 shows an example of a solar cell module cut into a predetermined size (hereinafter referred to as "solar cell module pieces"). Here, the size that can be fed into the crusher is determined by the size, capacity, crushing ability, etc. of the crusher, and is approximately 1 to 5 cm square. Furthermore, there is no particular limitation on the method for cutting the solar cell module 10.

[0023] In step S3, following cutting of the solar cell module 10 in step S2, the solar cell module pieces are placed in the crushing containers 101, 201 of a crusher (such as the impact crusher 100 or the airflow crusher 200), and the process proceeds to step S4. Here, the crusher used in the silicon recovery method of Example 1 is, for example, the impact crusher 100, the airflow crusher 200, a pin mill, a hammer mill, or the like.

[0024] The impact crusher 100 is a so-called mixer, and as shown in Fig. 5, has a crushing container 101 and a rotor 102 that rotates inside the crushing container 101 and stirs the input material (solar cell module pieces in Example 1). The crushing container 101 is, for example, a cylindrical type having an input port 103 that opens upward, and has a discharge port 104 at the lower side. A discharge valve 104a is attached to the discharge port 104, and is appropriately opened and closed by the discharge valve 104a. The rotor 102 has a rotating shaft 105 that penetrates the bottom surface 101a of the crushing container 101 along the vertical direction, a lower blade 106 fixed to the rotating shaft 105, and an upper blade 107 that is fixed to the rotating shaft 105 and attached above the lower blade 106. In the rotating body 102, the rotating shaft 105 is rotated by a driving device (not shown), and the lower blade 106 and the upper blade 107 rotate integrally with the rotating shaft 105.

[0025] In the impact crusher 100, the rotor 102 rotates in the crushing vessel 101, causing the lower blade 106 and upper blade 107 to collide with the input material (solar cell module pieces), and the input material is subjected to an impact force from the lower blade 106 and upper blade 107, so that the input material is stirred and crushed while being sheared. In the impact crusher 100, the input materials stirred by the rotor 102 are crushed even when they collide or rub against each other at high speed in the crushing vessel 101. In addition, the impact crusher 100 performs so-called batch processing. That is, a predetermined amount of solar cell module pieces is input into the impact crusher 100 before crushing, and then the entire amount of solar cell module pieces is stirred and crushed for a predetermined time, and then taken out.

[0026] The airflow type pulverizer 200 is a so-called autogenous pulverizer, and as shown in FIG. 6, it has a pulverizer container 201 and a rotor 202 that rotates inside the pulverizer container 201 and stirs the input (solar cell module pieces). The pulverizer container 201 is, for example, substantially cylindrical with an axial direction set horizontally, and an input port 203 and an outlet port 104 are formed at the top side in the axial direction. In addition, a step 201a is formed on the circumferential surface of the pulverizer container 201, the inner diameter of which decreases from the input port 203 side toward the outlet port 204 side. A doughnut-shaped classification plate 201b with an open center is detachably attached to the step 201a. In the airflow type pulverizer 200, the classification effect of the step 201a can be improved by attaching the classification plate 201b.

[0027] The rotor 202 has a rotating shaft 205 and an impeller 206 attached to the rotating shaft 205. The rotating shaft 205 penetrates the side surface 201c of the grinding container 201 on the side of the inlet 203 along the axial direction. In the rotor 202, the rotating shaft 205 is rotated by a driving device (not shown), and the impeller 206 rotates integrally with the rotating shaft 205.

[0028] In the air flow type crusher 200, the rotor 202 rotates in the crushing vessel 201, generating a strong swirling air current in the crushing vessel 201, causing the input materials (solar module pieces) to collide with each other and crush. Note that in the air flow type crusher 200, as in the impact type crusher 100, the impeller 206 also directly strikes and crushes some of the input materials. In addition, the air flow type crusher 200 performs a so-called one-pass process. That is, a fixed amount of solar cell module pieces are input into the air flow type crusher 200 while the air flow type crusher 200 is running, and the crushed materials that have been stirred and finely ground in the crushing vessel 201 are sequentially discharged.

[0029] Although not shown, the pin mill has a grinding container and a rotor that rotates inside the grinding container and stirs the input material. The rotor of the pin mill has a pair of circular disks to which many pins are fixed, and the pair of disks are arranged in a state where the pins are opposed to each other so that they interlock. In the pin mill, the pair of disks are rotated in opposite directions, or one disk is fixed and the other disk is rotated, and the input material is passed between the opposing disks, so that the input material is pulverized by impact and shear caused by the interlocking pins. In addition, the pin mill performs so-called one-pass processing. That is, a fixed amount of solar cell module pieces are fed into the pin mill while the pin mill is running, and the pulverized material is stirred and finely divided in the grinding container and then discharged one by one.

[0030] Although not shown, the hammer mill has a grinding container and a rotor that rotates inside the grinding container and stirs the input material. The rotor of the hammer mill has a rotating plate equipped with multiple hammers. In the hammer mill, the rotating plate rotates at high speed and the input material is pulverized by impact and stirring with the hammers. The pulverized material pulverized by the hammer mill is discharged and collected through a screen (mesh size 2 mm in Example 1) provided at the discharge outlet. The hammer mill also performs a so-called one-pass process. That is, a fixed amount of solar cell module pieces are fed into the hammer mill while the hammer mill is running, and the pulverized material that has been stirred and finely divided in the grinding container is discharged one by one.

[0031] In step S4 (second step), following the introduction of the solar cell module pieces into a crusher (such as the impact crusher 100 or the airflow crusher 200) in step S3, the introduced solar cell module pieces are crushed by the crusher, and the process proceeds to step S5. Here, the operating conditions of the crusher (mixing time, amount introduced per unit time, peripheral speed of the rotors 102, 202, etc.) are set arbitrarily.

[0032] In step S5 (third step), following the crushing of the solar cell module pieces in step S4, silicon is separated and recovered from the crushed material, and the process proceeds to the end. In the first embodiment, regardless of which crusher is used, after the crushing is completed, the crushed material is passed through a sieve with a predetermined mesh size, and silicon is separated and recovered from the crushed material by sieving to separate the material into oversieve and undersieve. Note that FIG. 7 shows the material recovered on the oversieve with a mesh size of 0.8 mm after crushing using the airflow crusher 200, and FIG. 8 shows the material recovered on the undersieve with a mesh size of 0.8 mm after crushing using the airflow crusher 200. When the crusher is an airflow crusher, silicon may be separated and recovered by airflow classification, which classifies the crushed material by utilizing an airflow generated in the crushing container 201.

[0033] The operation of the method for recovering silicon from the solar cell module 10 according to the first embodiment will be described below.

[0034] In the silicon recovery method of Example 1, first, at least the glass substrate 2 and the outer frame member 3 are removed from the solar panel 1 to obtain a solar cell module 10 (step S1). Next, the solar cell module 10 is cut to a predetermined size to obtain solar cell module pieces (see FIG. 4) (step S2). This makes it possible to feed the solar cell module 10 into a crusher.

[0035] The solar cell module pieces are then fed into an arbitrary crusher (such as the impact crusher 100 or the airflow crusher 200) (step S3), and crushed by the crusher (step S4). Here, the solar cell 11 containing silicon is harder and more brittle than the sealing material 13 and the protective sheet 14. On the other hand, both the sealing material 13 and the protective sheet 14 are more flexible than the solar cell 11 containing silicon. Therefore, when an impact is applied to the solar cell module pieces by crushing them with a crusher, the solar cell 11 is crushed relatively easily and becomes fine, but the sealing material 13 and the protective sheet 14 are not easily crushed and do not easily become fine. Therefore, in the silicon recovery method of Example 1, the solar cell module pieces are crushed to peel off the solar cell 11 from the sealing material 13 and the protective sheet 14, and the peeled solar cell 11 can be crushed finely.

[0036] After the pulverization is completed, the pulverized material is separated by sieving or the like, and silicon is recovered (step S5). At this time, the sealing material 13 and the protective sheet 14 are difficult to pulverize and do not easily break into small pieces, so they remain on the sieve, for example (see FIG. 7). In contrast, the brittle and finely pulverized solar cell 11 falls below the sieve, for example (see FIG. 8). Therefore, the silicon recovery method of Example 1 can easily separate the silicon contained in the solar cell 11 from the pulverized material, and can recover silicon from the solar cell module 10 without incurring costs or effort. Furthermore, since no organic solvents or the like are used, the environmental impact during silicon recovery can be reduced.

[0037] When the airflow type crusher 200 is used as the crusher, the airflow type crusher 200 has a classification function, so that the finely crushed solar cell 11 is quickly discharged from the crushing container 201 and collected, while the solar cell module pieces that have not been crushed can remain in the crushing container 201 and continue to be crushed. Therefore, the use of the airflow type crusher 200 can prevent silicon peeled off from the sealing material 13 from adhering again to the resin of the sealing material 13, etc., and allows the silicon to be collected more efficiently than when the impact type crusher 100 is used to crush the solar cell module pieces.

[0038] In addition, when the airflow type pulverizer 200 is used as the pulverizer, continuous processing is possible while classifying the material by airflow, so processing can be performed by a low-capacity motor. Therefore, for example, it is fully possible to use renewable energy such as solar power generation or wind power generation as a power source, and it is possible to recover silicon while suppressing carbon dioxide emissions.

[0039] The test results of the method for recovering silicon from the solar cell module 10 of Example 1 will be described below.

[0040] 9 shows the relationship between the stirring time for each circumferential speed of the rotor 102 and the amount of material recovered under the sieve when 63 g of solar cell module pieces cut into approximately 3 cm squares are fed into the impact crusher 100, stirred for a certain period of time at a prescribed circumferential speed by the impact crusher 100, and sorted by passing the crushed material through a sieve with a mesh size of 0.8 mm. Here, the "circumferential speed" refers to the speed at which the rotor 102 rotates (unit: meters per second (m / s)), and is determined by the length of the lower blade 106 or upper blade 107 (the distance from the rotating shaft 105 to the blade tip) and the rotation speed of the rotor 102 (rotating shaft 105). Specifically, it is calculated by the following formula (1). Circumferential speed V(m / s)=π×D×N / 1000 (1) D: diameter of the rotor 102 (mm) N: Rotation speed (rpm) In the first embodiment, the peripheral speed of the rotor 102 is set by the tip speed of the lower blade 106 .

[0041] In this case, as shown in Figure 9, the amount of under-sieve recovered is relatively small at a peripheral speed of 10 m / s, and it can be seen that the amount of under-sieve recovered hardly increases even if the mixing time is extended. Since silicon is recovered from the material that falls under the sieve, it is estimated that if the amount of under-sieve recovered is small, the absolute amount of silicon recovered will decrease. Therefore, it is desirable to have as much under-sieve recovered amount as possible.

[0042] And, when the peripheral speed is 20 m / s, the amount of under-sieve recovered is larger than that of the peripheral speed of 10 m / s regardless of the mixing time, and it can be seen that the longer the mixing time, the more the amount of under-sieve recovered increases. Also, at a peripheral speed of 35 m / s, the amount of under-sieve recovered at each mixing time is even greater than that at a peripheral speed of 20 m / s. However, at a peripheral speed of 40 m / s, the amount of under-sieve recovered is almost the same as at a peripheral speed of 35 m / s, and is only slightly higher. And, at a peripheral speed of 55 m / s, the amount of under-sieve recovered increases at each mixing time compared to the peripheral speeds of 35 m / s and 40 m / s, but even at a peripheral speed of 72 m / s, the amount of under-sieve recovered is almost the same.

[0043] That is, as shown in Fig. 9, in order to ensure a sufficient amount of under-sieve material collected when using a sieve with an opening of 0.8 mm, it was found that the peripheral speed of the rotor 102 in the crusher (particularly the impact crusher 100) is desirably set to 20 m / s or more. Furthermore, it was found that a peripheral speed of the rotor 102 of 35 m / s or more is more preferable because it can further increase the amount of under-sieve material collected.

[0044] 9, it was found that in pulverization using the impact pulverizer 100, when the peripheral speed is 35 m / s or more, the amount of undersize material recovered tends to become saturated when the mixing time is about 8 to 9 minutes. Therefore, in pulverization using the impact pulverizer 100 at a high peripheral speed, a mixing time of about 10 minutes is considered sufficient.

[0045] FIG. 10 also shows the relationship between the amount of silicon recovered from 1 kg of solar cell module pieces at each peripheral speed of the rotor 102, estimated from the material that falls below the sieve when 63 g of solar cell module pieces cut into 3 cm squares are placed into the impact crusher 100, stirred for 10 minutes at a specified peripheral speed by the impact crusher 100, and separated by passing the crushed material through a sieve with 0.8 mm openings, and the silicon recovery rate.

[0046] In this case, as shown in Figure 10, at a peripheral speed of 10 m / s, the amount of silicon recovered is small, but as the peripheral speed increases, the amount of silicon recovered increases and the silicon recovery rate gradually increases. It was also found that at a peripheral speed of 35 m / s or more, the amount of silicon recovered is almost the same regardless of the peripheral speed, and the amount of silicon recovered tends to saturate. However, since the amount of silicon recovered that falls below the sieve increases as the peripheral speed increases (see Figure 9), it is estimated that the amount of resin mixed into the material that falls below the sieve increases in proportion to the peripheral speed.

[0047] 11 shows the relationship between the amount of silicon recovered from 1 kg of solar cell module pieces for each circumferential speed of the rotor 202 estimated from the under-sieve recovered material when a fixed amount of solar cell module pieces cut into approximately 3 cm squares are fed into the air flow crusher 200, stirred at a predetermined circumferential speed by the air flow crusher 200, and separated through a sieve with an opening of 0.8 mm. Note that in Example 1, the circumferential speed of the rotor 202 was set to the tip speed of the impeller 206. Also, an experiment was performed with a classification plate 201b attached inside the crushing container 201.

[0048] In this case, as shown in Fig. 11, it was found that the amount of silicon recovered increases as the peripheral speed increases. However, when the peripheral speed is increased from 72.2 m / s to 117 m / s, the increase in the silicon recovery rate is small compared to when the peripheral speed is increased from 40 m / s to 72.2 m / s. Therefore, it is estimated that when the peripheral speed of the rotor 202 is too fast (for example, about 117 m / s), the amount of resin mixed in the undersize recovered material increases.

[0049] FIG. 12 shows the analysis results of the under-sieve recovered material and the silicon recovery results when solar cell module pieces cut into approximately 3 cm squares are fed into the impact crusher 100, the air flow crusher 200, a pin mill, and a hammer mill, respectively, solar cell module pieces cut into approximately 5 to 10 mm squares are fed into a ball mill, and after being crushed in each crusher, the crushed material is passed through a sieve with 0.8 mm openings for separation.

[0050] Here, the "resin mixing rate of the undersieve recovered material" is a value indicating the amount of resin components mixed in the undersieve recovered material. The "silicon content based on the fluorescent X-ray analysis of the undersieve recovered material" is a value indicating the content rate of silicon relative to the mass of the undersieve recovered material, which is obtained by analyzing the undersieve recovered material subjected to thermal decomposition treatment using a fluorescent X-ray analyzer and quantitatively analyzing the elements contained therein. The "silicon content rate of the undersieve recovered material" is a value indicating the amount of silicon mixed in the undersieve recovered material. The "amount of silicon recovered from a 1 kg solar cell module piece" is a value indicating an estimated value of the mass of silicon that can be recovered from a 1 kg solar cell module piece. The "amount of silicon recovered from a 63 g solar cell module piece" is a value indicating the mass of silicon that can be recovered from a 63 g solar cell module. The "silicon recovery rate from the solar cell module piece" is a value indicating the recovery rate of silicon recovered from the solar cell module piece.

[0051] The "resin mixing ratio of the undersize collected material" was calculated by the following procedure. That is, first, the mass of the undersize collected material is measured. Next, the undersize collected material is heated to a high temperature in an air atmosphere using an electric furnace, and a thermal decomposition process is performed to thermally decompose the resin components contained in the collected material. Then, the mass of the undersize collected material after the thermal decomposition process is measured. Then, the mass of the resin components mixed in the undersize collected material is calculated from the mass difference of the undersize collected material before and after the thermal decomposition process, and the ratio to the mass of the undersize collected material is calculated to be the "resin mixing ratio of the undersize collected material". In the thermal decomposition process of the undersize collected material, the temperature is raised from room temperature to 600°C in an electric furnace in an air atmosphere over 1 hour, and then the heated state of 600°C is maintained for 4 hours, and then naturally cooled.

[0052] The "silicon content of the undersieve recovered material" is calculated based on the results of X-ray fluorescence analysis by subtracting the mass of the resin components contained in the undersieve recovered material from the mass of the undersieve recovered material.

[0053] The "amount of silicon recovered from a 1 kg solar cell module piece" is calculated based on the results of the "amount of silicon recovered from a 63 g solar cell module piece" described below.

[0054] The "amount of silicon recovered from a 63 g solar cell module piece" is calculated using the mass of silicon contained in the 63 g solar cell module piece and the "silicon content of the undersieve recovered material." The "mass of silicon contained in a 63 g solar cell module piece" is calculated using the following procedure.

[0055] First, multiple samples of solar cell module pieces were measured, and the unit area (1 cm 2 13, the mass per unit area of ​​the solar cell module piece is calculated as 0.182 g / cm, which is the average of the solar cell module pieces of samples No. 1 to No. 5. 2 Then, the calculated "mass per unit area of ​​the solar cell module piece" is used to calculate the "area of ​​the 63g solar cell module piece." (That is, 63÷0.182=346.15cm 2 ).

[0056] On the other hand, a micrograph of the cross section of the solar cell module piece (see Figure 14) shows that the thickness of the crystalline silicon layer contained in the solar cell module piece is about 180 μm. Also, the specific gravity of silicon is 2.33 g / cm 3 (known). Therefore, from these values, the solar cell module piece is 2 ) contains 0.042 g (2.33 x 0.0180) of silicon.

[0057] And the area of ​​the 63g solar cell module piece (346.15 cm 2 ) and the silicon content of the solar cell module piece per unit area (0.042 g), the mass of silicon contained in the 63 g solar cell module piece is calculated, which in this case is found to be approximately 14.54 g (346.15 × 0.042).

[0058] The "silicon recovery rate from solar cell module fragments" is calculated based on the mass of silicon contained in the under-sieve recovered material and the "amount of silicon recovered from a 63 g solar cell module fragment" from the results of pyrolysis of the resin and quantitative X-ray fluorescence analysis.

[0059] Furthermore, the results shown in FIG. 12 show that silicon can be recovered from solar cell modules regardless of whether the solar cell module pieces are crushed using the impact crusher 100, the air flow crusher 200, a pin mill, or a hammer mill.

[0060] On the other hand, when the solar cell module pieces were pulverized using a ball mill, the shape of the solar cell module pieces did not change after 30 minutes of pulverization, and it was found that the solar cell module pieces were not pulverized. The ball mill is a device that puts a pulverization medium and a material to be pulverized into a pulverization container, stirs the material to be pulverized with the pulverization medium, and produces fine powder. Here, 170 g of zirconia balls with a diameter of 10 mm were put in as the pulverization medium, and 3.8 g of solar cell module pieces cut into a size of about 5 to 10 mm square was put in as the material to be pulverized. After 30 minutes of pulverization, a small amount of black-brown powder that seemed to be silicon powder was confirmed, but most of it was in a state of being applied to the surface of the solar cell module, and it was difficult to recover only the powder of the solar cell 11. Therefore, it was found that it was difficult to recover silicon from the solar cell module 10 when a ball mill was used as the pulverizer.

[0061] It was found that when the air flow type crusher 200 was used as the crusher and the peripheral speed of the rotor 202 was set to 117 m / s (sample number 11), the "silicon recovery rate from the solar cell module pieces" reached 87.1%, achieving a high recovery rate. It was also found that when the air flow type crusher 200 was used to crush the rotor 202 and the peripheral speed was set to 117 m / s (sample number 11), the "amount of silicon recovered from 1 kg of the solar cell module pieces" was the highest, compared to crushing using other crushers or crushing using the air flow type crusher 200 at other peripheral speeds.

[0062] In addition, when comparing the case where the impact crusher 100 is used for crushing and the case where the airflow crusher 200 is used for crushing, with the peripheral speed of the rotors 102, 202 being the same (sample numbers 6 and 8), it was found that the "recovery rate of silicon from the solar cell module pieces" was higher when the airflow crusher 200 was used as the crusher. By attaching a screen instead of the discharge valve 104a of the impact crusher 100 and leaving the discharge port open during crushing, it becomes possible to quickly discharge the crushed material from the crushing vessel 101. In this case, the solar cell module pieces are not crushed unnecessarily, and it is considered possible that the recovery rate can be improved.

[0063] Furthermore, when pulverization was performed using the air flow pulverizer 200, a comparison was made with the presence or absence of the classification plate 201b (sample numbers 8 and 9), and it was found that the presence or absence of the classification plate 201b did not have a significant effect on the "amount of silicon recovered from a 1 kg solar cell module piece."

[0064] In addition, when crushing using the air flow crusher 200, a comparison was made under different conditions of the supply amount of solar cell module pieces (sample numbers 9 and 10). It was found that when the rotor 202 was set to the same circumferential speed and the supply amount was increased, the “silicon recovery rate from the solar cell module pieces” decreased and the “resin contamination rate in the under-sieve recovered material” increased compared to when the supply amount was smaller.

[0065] It was found that when the solar cell module pieces were crushed using a pin mill as a crusher, although some small resin pieces were mixed in with the under-sieve recovered material, most of the resin pieces were recovered above the sieve, and the crushed silicon was contained below the sieve. However, when comparing the crushing using the impact crusher 100 and the crushing using the airflow crusher 200 under the condition of the circumferential speed of the rotor (sample numbers 6, 8, and 12), it was found that the "amount of silicon recovered from 1 kg of solar cell module pieces" was less than half. For this reason, it is considered that the use of a pin mill as a crusher is less advantageous for recovering silicon than the use of the impact crusher 100 or the airflow crusher 200.

[0066] In addition, when the solar cell module pieces were crushed using a hammer mill as a crusher, most of the resin pieces and uncrushed solar cell module pieces remained in the crushing container. In addition, analysis of the crushed material that passed through the screen and was collected revealed that the "silicon recovery rate from the solar cell module pieces" was lower than when the solar cell module pieces were crushed using other crushers. Furthermore, when comparing the crushing using the impact crusher 100 with the peripheral speed of the rotor as a condition (sample numbers 3 and 13), it was found that the "silicon recovery rate from the solar cell module pieces" was less than half. For this reason, it is considered that the use of a hammer mill as a crusher is less favorable for recovering silicon than the use of the impact crusher 100 or the airflow crusher 200.

[0067] The method for recovering silicon from solar cell module 10 of the present invention has been described above based on Example 1. However, the specific configuration is not limited to Example 1, and design changes and additions are permitted as long as they do not deviate from the gist of the invention according to each claim.

[0068] In the silicon recovery method of Example 1, an example is shown in which the crushed material after crushing is passed through a 0.8 mm sieve regardless of the type of crusher, and silicon is separated by sieving. However, the method of separating silicon from the crushed material is not limited to this. For example, when the crusher is an airflow type crusher 200, silicon may be separated by airflow classification that separates silicon according to particle size using an airflow. In addition, the opening of the sieve used for sieving can be set arbitrarily, and although it is set to 0.8 mm in Example 1, it is not limited to this.

[0069] Examples of pulverization using an impact pulverizer 100, an airflow pulverizer 200, a pin mill, and a hammer mill have been shown. However, the pulverizer is not limited to these, and any pulverizer that pulverizes without using a pulverizing medium, such as a jet mill, may be used. [Explanation of symbols]

[0070] 1. Solar panels 2. Glass substrate 3 Outer frame components 10. Solar Cell Module 11 Solar Cell 12 Metal Pattern 13 Encapsulating materials 14 Protective Sheet

Claims

1. a first step of cutting a solar cell module from which an outer frame member and a glass substrate have been removed, the solar cell module having at least a solar cell containing silicon, a resin sealing material sealing the periphery of the solar cell, and a resin protective sheet covering the sealing material on the back side of the solar cell; a second step of crushing the solar cell modules by a crusher having a crushing container into which the cut solar cell modules are introduced and a rotor that stirs the introduced material in the crushing container; A third step of separating and recovering the silicon from the pulverized material pulverized by the pulverizer by sieving or air classification; A method for recovering silicon from a solar cell module, comprising:

2. The method for recovering silicon from a solar cell module according to claim 1, In the second step, the peripheral speed of the rotating body is set to 20 meters per second or more. A method for recovering silicon from a solar cell module.

3. The method for recovering silicon from a solar cell module according to claim 2, In the second step, the peripheral speed of the rotating body is set to 35 meters per second or more. A method for recovering silicon from a solar cell module.

4. The method for recovering silicon from a solar cell module according to any one of claims 1 to 3, The pulverizer is an impact pulverizer that applies an impact force from the rotor to the input material to shear and mix it. A method for recovering silicon from a solar cell module.

5. The method for recovering silicon from a solar cell module according to any one of claims 1 to 3, The pulverizer is an airflow type pulverizer that generates a swirling airflow in the pulverizing container by the rotor and pulverizes the charged materials by colliding them with each other. A method for recovering silicon from a solar cell module.

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