JP2016093804A - Method of recovering valuable material from solar cell module and processing equipment for recovering the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of completely decomposing a polymer of ethylene vinyl acetate or the like in a solar cell module and recovering a valuable material in a short time at a low cost.SOLUTION: In a method of recovering a valuable material from a solar cell, a solar cell module 5 as an object to be processed is loaded on a support of catalyst carrying honeycomb 8 which carries an oxide semiconductor and has air permeability while setting a light-receiving surface upward, the oxide semiconductor is brought into contact with a back sheet 7 of the solar cell module 5, the solar cell module 5 is heated at such a temperature that the oxide semiconductor comes to a genuine conductive region under the existence of oxygen, thereby, a polymer 4 in the solar cell module 5 is completely decomposed into water and carbon dioxide gas, the valuable material such as glass 1, a solar battery cell and an inter-connector 3 is recovered, exhaust gas from a heating processing chamber is made harmless by a VOC cleaning device provided with an oxide semiconductor carrying honeycomb connected to an exhaust port.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for recovering valuable materials from a solar cell module and a processing apparatus for recovering.

One of the inventors of the present invention is a method for decomposing an object to be processed such as an organic substance, a polymer, a gas body, etc., by heating a semiconductor to a temperature that becomes an intrinsic electric conduction region to generate a large amount of electron / hole carriers, Is a treatment method (semiconductor thermal activation of semiconductor-conductors, hereinafter abbreviated TASC). (Patent Document 1, Non-Patent Document 1). A semiconductor that can be used in the TASC method may be a semiconductor that is stable in a high temperature and oxygen atmosphere. Therefore, an oxide semiconductor is preferably used. Examples of oxide semiconductors include BeO, CaO, CuO, Cu ₂ O, SrO ₂ , BaO, MgO, NiO, CeO ₂ , MnO, GeO, PbO, TiO, VO, ZnO, FeO, PdO, Ag ₂ O, TiO. ₂ , MoO ₂ , PbO ₂ , IrO ₂ , RuO ₂ , Ti ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Cr ₂ O ₃ , ZrO ₂ , WO ₃ , MoO ₃ , WO ₂ , SnO ₂ , Co ₃ O ₄ , Sb ₂ O ₃ , Mn ₃ O ₄ , Ta ₂ O ₅ , V ₂ O ₅ , Nb ₂ O ₅ , MnO ₃ , Fe ₂ O ₃ , Y ₂ O ₂ S, MgFe ₂ O ₄ , NiFe ₂ O _{4 , ZnFe 2 O 4, ZnCo 2} O 4, MgCr 2 O 4, FeCrO 4, CoCrO 4, CoCrO 4, ZnCr 2 O 4, CoAl 2 O 4, NiAl 2 O 4 and the like That. Among these, chromium oxide (Cr ₂ O ₃ ) is excellent in high-temperature stability (melting point: about 2200 ° C.) and is a safe material used for dyeing glass bottles for beverages. In addition, iron oxide (α-Fe ₂ O ₃ : hematite) is a safe and inexpensive material and thus has high practicality.

An oxide semiconductor used in the TASC method is an insulator at room temperature, but enters an intrinsic electric conduction region of the semiconductor when heated to 350 to 500 ° C. At that time, the holes generated in the valence band develop a strong oxidizing power, take away the bonding electrons from the polymer or the like, and form unstable cation radicals in the polymer. Next, this radical propagates in the polymer that is the decomposition product, destabilizing the entire polymer, and the polymer is cut into small molecules such as ethylene (radical cleavage) in a form that self-destructs, and in the air Reacts with oxygen and completely decomposes into water and carbon dioxide. In other words, the decomposition process consists of the formation of radicals by the oxidizing power of holes, fragmentation by radical cleavage, and complete combustion of the cut molecules and oxygen. This technique is characterized in that radical propagation occurs even when the thickness of the polymer is 20 mm or more, and the decomposition effect reaches the inside of the decomposition target.
In addition, the same TASC method is used for fiber-reinforced plastics, and a method of completely disassembling the plastics and completely recovering the reinforcing fibers such as carbon fibers and glass fibers without damage is proposed (Patent Document 2, Non-Patent Document 2). ). This method is very useful because it can recover and reuse reinforcing fibers without causing damage such as cutting high-cost carbon fibers, etc., and is not limited to reinforcing fibers. It is a universal method that can recover only inorganic substances from a composite material in which a polymer and a polymer are mixed.

  Solar power generation systems do not require fuel, so there is no concern about resource depletion, and they are a useful technology that supplies clean energy and does not give an impact to the environment. The service life of the solar cell module, which is the main component of the solar cell system, is said to be 20-30 years, and a large amount of processing demand is expected in the future. Reuse of solar cell module parts as they are is not economical in terms of cost, and establishes recycling technology for processing unnecessary parts and recovering valuable materials such as tempered glass, solar cells, and inter-connectors. Is desired.

  However, most of the present solar cell modules have a structure in which the cell portion and the glass substrate are bonded by, for example, EVA (ethylene vinyl acetate copolymer resin: ethylene vinyl acetate) which is a thermoplastic resin. . EVA prevents the cell from being exposed to the atmosphere and corroded, but conversely, if the cell part or glass is separated and taken out, it is difficult to take out because there is no way to remove EVA efficiently. In fact, recycling technology has not been put to practical use. Generally, it is known that when a polymer is thermally decomposed at room temperature and in air, a black residue derived from many carbides or the like remains, depending on the combustion method.

  As a method for recovering the solar cell element constituent material by removing EVA, Japanese Patent Laid-Open No. 2014-108375 discloses that the oxygen concentration in the furnace is 1 to 3% by volume, and the temperature in the apparatus furnace is “preheating part”. : 300 ° C. ”and“ heat treatment section: 500 ° C. ”, and the rotational speed of the circulating conveyor is adjusted so that“ preheating section stay time: 20 minutes ”and“ heat treatment section stay time: 20 minutes ”. Put the crystalline Si module in the continuous processing equipment, remove the EVA sealing material bonded to the cell part and the glass substrate without causing an explosion phenomenon or carbonization, and make the constituent material of the solar cell element safe and low cost. It is described that it can be recovered. In order to suppress the explosion, it is preferable to reduce the oxygen concentration. However, this leads to promotion of carbonization of the polymer, and problems such as a reduction in processing speed remain. JP-A-2004-42033 improves the conventional nitric acid dipping method, and by adding a surfactant to nitric acid heated to 70 ° C. or higher and 80 ° C. or lower for dipping the solar cell module, it takes 100 hours conventionally. It is described that the degradation time of EVA that had been reduced could be reduced to about half of 50 hours. Although there is an advantage that the cells can be recovered without cracking during the treatment, the treatment time is still long, and further, it is not practical because a strong acid is used.

  Therefore, if the “semiconductor thermal activation technology (TASC)” that is the method of the present application is applied to the removal of EVA, the TASC method is a clean technology that completely decomposes the polymer into water and carbon dioxide. It is possible to construct a system that easily and inexpensively collects glass, solar battery cells, inter-connectors, and the like that are valuable materials from the battery module.

Japanese Patent No. 4517146 JP 2013-146649 A JP 2014-108375 A JP 2004-42033 A

T.A. Shinbara, T .; Makino, K .; Matsumoto, and J.M. Mizuguchi: Complete decomposition of polymerics by partially generated holes at high temperatures in titanium dioxide and its decompositions. Appl. Phys. 98, 044909 1-5 (2005) Hitoshi Mizuguchi: Complete decomposition, recycling technology and processing technology of FRP by thermal activation of semiconductors 47, 37-47 (2012)

  As described above, in the recycling of the solar cell module, it is difficult to remove the polymer such as EVA of the solar cell element, which hinders the practical use of the recovery of the constituent material of the solar cell element. This problem is solved by a semiconductor thermal activation method (TASC), and a method of recovering valuable glass, solar cells, inter-connectors, etc. by completely decomposing polymers such as EVA in the solar cell module. This is the issue. It is another object of the present invention to provide a method for separating and recovering silicon wafers and metal electrodes constituting solar cells.

  In the present invention, the semiconductor thermal activation technology (TASC) is applied to dismantling the solar cell module, the oxide semiconductor is brought into contact with the surface of the solar cell module to be processed, and the oxide semiconductor is formed in the presence of oxygen. By heating the object to be processed at a temperature that becomes an intrinsic electric conduction region, a polymer such as EVA is completely decomposed to recover valuable glass, solar cells, and inter-connectors. The collected solar cells are immersed in concentrated nitric acid to dissolve the silver electrode, hydrochloric acid is dropped into this to collect AgCl, and the remaining silicon wafer is separated and collected.

In the solar cell module, tempered glass is disposed on the light-receiving surface side of the solar cells connected to each other via electrodes, and the peripheral portion of the solar cell is hermetically filled with a polymer such as EVA, and is made of an organic film. The sheet has a structure bonded to the back side of a polymer such as EVA.
The present inventor has conducted extensive experiments in order to completely decompose and remove polymers such as EVA from such a solar cell module and recover valuable materials, and has reached the present invention through the following processes.
As described above, the decomposition of the polymer by the TASC method is a process in which radicals generated by hole oxidation deprive the polymer of bond electrons, destabilize the polymer and cut into small molecules. Although it has been stated that radicals propagate even when they are 20 mm or more, the extent to which radicals can propagate in the polymer is the key to solving the problem.
Judging from the structure of the solar cell module described above, if an oxide semiconductor is brought into contact with the bottom backsheet, the solar cells (which are inorganic) are stretched over the backsheet. It was assumed that the propagation of radicals was interrupted here and did not reach the interface between the solar cell and the glass. Therefore, an experiment was performed in which a dispersion film of an oxide semiconductor was applied to four lateral sides of a solar cell module (120 × 120 × 5 mm), and radicals were run in the lateral direction. Although radicals could not be expected to run through to 60 mm, much more than 20 mm, as a result of actual TASC processing, surprisingly, solar cell modules, including backsheets, all polymers were completely decomposed, and the modules were made from glass. The silicon wafer and the interconnector were separated and recovered, and the inorganic substance filled in the polymer could be recovered as a residue.

  What is more surprising is that the same result was obtained even when the coating on the four sides of the module was made into three sides, two sides and one side. That is, it was confirmed that radicals were sufficiently propagated even in a 120 mm square surface of the module. It was expected that radicals would span the entire module of a given size if the module temperature was sufficient. Then, when the oxide semiconductor was coated on the end surface of one short side of the module piece having a long side length of 330 mm and subjected to TASC treatment in the horizontal direction, the polymer in the combined module was completely decomposed as expected. Based on this result, the module backsheet was placed on a honeycomb supporting an oxide semiconductor and subjected to TASC treatment. As a result, all the polymers were completely decomposed, and the glass, silicon wafer, inter- The connector could be separated and recovered. As a result, it was found that the radical propagates to the glass surface through a small space between the solar cells arranged on the entire surface on the back sheet, and completely decomposes the filled polymer. Based on the above results and discussion, the present invention has been completed. The method of placing the module back sheet on the honeycomb supporting the oxide semiconductor and performing the TASC treatment is an operation of simply placing the module piece on the catalyst supporting honeycomb with the back sheet down. This is the cleanest processing method that does not require a coating process of a physical semiconductor, and further does not mix oxide semiconductor powder into the recovered material.

That is, in the method for recovering valuable materials from the solar cell module according to the present invention, the solar cell module that is the object to be processed is placed on the air-permeable support carrying the oxide semiconductor with the light receiving surface facing up. By placing the oxide semiconductor in contact with the back sheet of the solar cell module and heating the object to be processed at a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region in the presence of oxygen, It is characterized by decomposing and removing the polymer in the treated product and recovering valuable materials from the disassembled product.
In addition, the solar cell module which is a to-be-processed object can also use what made the solar cell module a panel shape as a processing object, and what was separated into the piece of the size which is easy to process, or what was crushed Etc. can be processed. The object to be processed in the present invention is not particularly limited in the size and form of the solar cell module.
In the present invention, the air-permeable support means a porous or honeycomb-like support having good air permeability. In the TASC method, sufficient oxygen is necessary to completely decompose the cut molecules into water and carbon dioxide gas, and a method of supporting an object to be treated on a highly breathable support is effective. .

Further, as another method of recovering valuable materials from the solar cell module, the solar cell module suspension sheet is dip-coated on a suspension of an oxide semiconductor to dip-coating the solar cell module suspension sheet. An oxide semiconductor is brought into contact with a back sheet, the object to be processed is placed on a gas-permeable support, and the object to be processed is at a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region in the presence of oxygen. The polymer in the object to be treated is decomposed and removed by heating, and valuable materials are recovered from the disassembled object, and 1 to 4 side surfaces of the solar cell module that is the object to be treated are oxidized. By dip-coating the semiconductor suspension, an oxide semiconductor is brought into contact with the side surface of the object to be treated, and the object to be treated is made of a breathable support. In the presence of oxygen, by heating the object to be processed at a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region, the polymer in the object to be processed is decomposed and removed, and valuable materials are removed from the dismantled material. It collects.
The support used when the object to be processed is treated by dip coating with an oxide semiconductor may be one that does not carry an oxide semiconductor on its surface, or one that carries an oxide semiconductor. It may be.

Further, the continuous processing apparatus for recovering valuable materials from the solar cell module according to the present invention has a breathability in which the solar cell module as the object to be processed is mounted in a state where the oxide semiconductor is brought into contact with the solar cell module. A conveyor that transports the support having a constant speed, and a heat treatment unit that heats the object to be processed mounted on the breathable support to a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region, or An air supply mechanism for supplying air into the heat treatment unit, and a recovery unit for recovering valuable materials from a dismantled product obtained by decomposing and removing the polymer in the object to be processed in the heat treatment unit. It is characterized by.
In the collection unit for collecting valuable materials from the dismantled material, the glass is first collected, and then the solar battery cell and the interconnector are collected and separated and collected.

The processing apparatus for recovering valuable materials from the solar cell module has a heat treatment chamber in which the solar cell module is installed in a state where the oxide semiconductor is in contact with the solar cell module that is the object to be processed, and the heating In the processing chamber, the object to be processed is heated to a temperature higher than the temperature at which the oxide semiconductor becomes an intrinsic electric conduction region, and the heat treatment unit exhausts an air inlet for supplying air from the outside and a gas generated by the heat treatment. A VOC purifying apparatus having a breathable structure carrying the oxide semiconductor is connected to the exhaust port of the heat treatment chamber, and the structure includes the oxide semiconductor By heating to a temperature equal to or higher than the intrinsic electric conduction region, the gas discharged from the heat treatment unit or the heat treatment chamber and passing through the VOC purification device is purified to a harmless gas. , From the heating chamber the object to be treated polymer demolition product obtained by decomposing and removing in the, and recovering a valuable substance.
In the present invention, the air-permeable structure means a porous or honeycomb structure having good air permeability. In the TASC method, sufficient oxygen is required to completely decompose the cut molecules into water and carbon dioxide, and a method of purifying the gas to be processed through a highly breathable structure is effective.

  According to the present invention, by treating the solar cell module with the semiconductor thermal activation method (TASC), it is possible to completely decompose and remove polymers such as EVA, which is an organic substance, so that it is a valuable resource from a dismantled product. Glass, solar cells, and inter-connectors can be collected in a short time at a low cost. Further, by completely decomposing and removing a polymer such as EVA, an effect of reducing the waste size can be obtained. Furthermore, silver and silicon wafers can be separated and recovered from the solar cells by acid treatment.

3 is a cross-sectional view of a solar cell module 5 placed on a catalyst-supporting honeycomb 8. FIG. It is the photograph which shows the collect | recovered glass 1, the photovoltaic cell 2, and the interconnector 3. FIG. It is sectional drawing of a solar cell module processing apparatus. 3 is a top view illustrating an example in which an oxide semiconductor 13 is coated on a side surface of a solar cell module 5. FIG. It is explanatory drawing of the procedure which mounts the solar cell module 5 on the catalyst carrying | support honeycomb 8 in which the stainless steel net | network 14 was put. It is a top view of the TASC continuous processing apparatus 15 for solar cell modules. It is a top view of the TASC processing apparatus 22 for solar cell modules.

A solar cell is the smallest unit that can be used by connecting cells together and protected by glass or polymer. This is called a solar cell module, and the solar cell module is put into a panel made of aluminum or other material. It is called. Furthermore, the array of solar cell panels is called a solar cell array. What is installed on the roof of a house is a solar cell array. The processing unit in the present application is the solar cell module 5 that has finished its service life or a solar cell module that has become defective during the manufacturing process.
A solar cell made of monocrystalline or polycrystalline silicon is formed by forming an n-type silicon layer on top of a p-type silicon wafer and further arranging electrodes and the like. As shown in FIG. 1, the solar cells are connected to each other by a metal interconnector 3 and are connected to an external electrode through a terminal 6. A tempered glass 1 having a thickness of about 3 to 5 mm is disposed on the light receiving surface side of the solar battery cell 2. The periphery of the combined solar cells 2 is hermetically filled with a polymer 4 such as EVA. Thereafter, the back sheet 7 is bonded to a polymer 4 such as EVA. The back sheet 7 is an organic film having various performances.

In order to collect the solar battery cells 2 and the like from the solar battery module 5, first, the aluminum frame of the solar battery panel is removed, and a module piece of about 120 × 120 × 5 mm is cut out. This module piece is brought into contact with an oxide semiconductor 13 such as Cr ₂ O ₃ in an electric furnace at 500 ° C. for 20-30 minutes in the air, and polymer components (polymer for fixing the frame and module, EVA as a filler, etc.) The polymer 4 and the underlying back sheet 7 are completely disassembled, and the module piece is completely disassembled. As a method of bringing the oxide semiconductor into contact with the solar cell module 5, the solar cell module 5 is placed under the module back sheet 7 (that is, the light receiving surface is placed on the honeycomb (catalyst supporting honeycomb 8) coated with the oxide semiconductor. The above method may be any one of a method of placing the oxide semiconductor 13 on the bottom surface of the module, and a method of applying a dispersion film of the oxide semiconductor 13 on the side surface of the solar cell module 5. FIG. 1 shows a case where the solar cell module 5 is placed on the catalyst supporting honeycomb 8.

  Since the module piece after the treatment is in a state where the heat strengthened glass 1 is cracked, the solar cell module after the TASC treatment in order to efficiently separate the glass 1, the solar battery cell 2, the inter-connector 3 and the residue. It is better to move 5 onto a meshed stainless steel plate. When the stainless steel mesh 14 is tilted and vibrated at a low frequency, the inorganic white residue contained in the polymer falls through the mesh, and the glass lump, the solar battery cell 2 and the inter connector 3 slide down the stainless steel mesh 14. Can be collected separately. It is preferable to provide grooves in the honeycomb in advance and insert the stainless steel mesh 14 because the residue on the stainless steel mesh 14 can be easily removed from the honeycomb.

In this manner, the heat-resistant glass 1, the solar battery cell 2, and the inter-connector 3 are easily recovered as shown in FIG. 2 from the dismantled product after the solar cell module 5 is subjected to the TASC treatment.
A grid-like silver electrode is formed on the light receiving surface of the collected solar battery cell 2 and an Al electrode is formed on the entire back surface. The solar battery cell 2 is put into a concentrated nitric acid solution to dissolve both metals, and then hydrochloric acid is added dropwise to isolate silver as a chloride (AgCl) precipitate. The remaining silicon wafer is recovered as a metal-free silicon substrate.

  As a practical method for recovering the glass 1, the solar battery cell 2, and the inter connector 3 from the solar battery module 5, it is preferable to use a continuous processing apparatus. This is provided with a carry-in unit, a preheating unit, a TASC processing unit, a cooling unit, a carry-out unit, and a sorting and collecting unit on a conveyor that is conveyed at a constant speed. The solar cell module 5 placed on the honeycomb is carried in from the carrying unit, TASC processing is performed in the TASC processing unit, carried out from the carry-out unit, and the glass 1, solar cells 2, inter-connector in the sorting and collecting unit 3 is collected separately.

Example 1
An experiment was performed using a solar cell panel (model: VLXA-125) manufactured by Next Energy & Resource Co., Ltd. First, an outer frame made of Al was cut from a solar cell panel having a size of about 800 × 1600 × 40 mm with a diamond cutter and removed. The outer frame and the solar cell array were bonded with a black binder resin. One piece of the solar cell module 5 having a size of 120 × 120 × 5 mm was cut out so as to contain the black adhesive resin, and used as a dismantled sample for TASC treatment. The upper surface of the solar cell module 5 has a glass plate of about 3.5 mm, and the lowermost surface has a white polymer sheet (back sheet 7) of about 0.5 mm, between the glass plate and the polymer sheet. Had a transparent resin layer (filler) of about 1 mm.

The back sheet 7 of the solar cell module 5 was placed on a honeycomb of cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ) composition coated with Cr ₂ O ₃ as the oxide semiconductor 13. Since the oxide semiconductor 13 does not change or consume itself in the TASC process, it acts to decompose and remove organic substances in the object to be processed, so that the honeycomb supporting the oxide semiconductor 13 is a catalyst. Also referred to as a supporting honeycomb 8. The catalyst-supporting honeycomb 8 on which one piece of the solar cell module 5 is placed is placed in the electric furnace 9 of FIG. 3, and the heater 10 is energized while introducing air from the air introduction port 11 to raise the temperature to 500 ° C. for 30 minutes. The temperature was controlled at 500 ° C. Thereafter, the temperature control power supply was turned off to cool. Through the series of TASC processes described above, the back sheet 7 of the module piece and the polymer constituting the filler are completely decomposed, and in order from the lower layer, a cloth that appears to be a thin glass fiber, an inter connector 3 / solar cell 2 / Interconnector 3 and a lump of glass that was further cracked were obtained. The decomposed polymer becomes water and carbon dioxide gas and is discharged from the exhaust port 12. The oxide semiconductor 13 (Cr ₂ O ₃ ) and the solar cell module 5 are in contact with each other only on the surface of the back sheet 7. And unstable cation radicals are formed in the polymer. This radical propagates in the polymer, which is the decomposition target, destabilizes the whole polymer, and the polymer is cut into small molecules such as ethylene (radical cleavage) in such a way that it self-destructs. Reacts and decomposes completely into water and carbon dioxide. This is a feature of the TASC method. That is, once radicals are formed on the polymer surface, the decomposition reaction continues in the thickness direction, so that complete decomposition is realized up to the filler region.

The disassembled module was removed from the cloth that appeared to be glass fiber and transferred to a 5 mesh stainless steel mesh 14. When this was tilted by about 30 degrees and vibrated at a low frequency, the glass lump fell to roll. Next, when the frequency was increased, the solar battery cell 2 and the inter connector 3 were also dropped and separated and collected. During this time, inorganic white residues (filler: TiO ₂ , CaCO ₃ , SiO _2, etc.) contained in the polymer dropped through the mesh. Through the above operation, as shown in FIG. 2, the glass lump, the solar battery cell 2 and the interconnector 3 could be easily separated. The angle at which the stainless steel mesh 14 is inclined is preferably 20 degrees or more and 40 degrees or less. The frequency for dropping the glass lump (first frequency) is in the range of 5 Hz to 20 Hz, and the frequency (second frequency) for dropping the solar cells 2 and the interconnector 3. ) May be set to an optimum value in the range of 10 Hz to 200 Hz depending on the thickness of the glass and the structure of the solar battery cell. The intensity of vibration should be adjusted as appropriate so that it can be separated and collected.

  The inter-connector 3 is a metal having a width of 2 mm, a thickness of 0.2 mm, and a length of about 100 mm. As a result of fluorescent X-ray analysis, it was found that copper and tin are the main components. Further, a grid-like electrode was screen-printed on the light receiving surface of the solar battery cell 2. As a result of fluorescent X-ray analysis, it was found that the solar cell 2 and the grid-like electrode material are mainly composed of silicon and silver, respectively. The silver electrode on the light receiving surface of the solar battery cell 2 was collected as AgCl by the following procedure. First, the solar cell 2 with a silver electrode was dissolved with concentrated nitric acid to obtain a light yellow solution. Next, hydrochloric acid was added dropwise thereto to precipitate silver as AgCl. After washing with water, filtration and drying were performed to obtain AgCl powder. From 9.6 g of solar cells, 0.3 g of AgCl was recovered (about 3.2% by weight).

Example 2
A piece of the same solar cell module 5 was cut out from the solar cell panel used in Example 1. As the oxide semiconductor 13, α-Fe ₂ O ₃ (iron oxide: hematite) was used instead of Cr ₂ O ₃ used in Example 1, and the same TASC treatment as in Example 1 was performed. As a result, the same good results as in Example 1 were obtained.

Example 3
A piece of the same solar cell module 5 was cut out from the solar cell panel used in Example 1. On the polymer sheet (back sheet) on the lower surface of the module, a suspension of Cr ₂ O ₃ was coated by about 5 to 10 microns by spray coating. With this surface facing down, it was placed on a honeycomb of cordierite composition of solid (Cr ₂ O ₃ not coated) and heated in air at 500 ° C. for 30 minutes (TASC treatment). The polymer of the module piece was completely decomposed in the same manner as in Example 1, the glass 1, the solar battery cell 2, and the interconnector 3 were easily separated, and the grid-like silver electrode was also recovered in the form of AgCl. Note that although a honeycomb in which an oxide semiconductor is not supported is used, a honeycomb in which an oxide semiconductor is supported may be used. In addition, a support body on which module pieces are placed may be used as long as it is not a honeycomb, but the TASC method requires sufficient oxygen to completely decompose the cut molecules into water and carbon dioxide gas. A porous support is preferred.

Example 4
In Example 3, instead of coating the bottom side of one piece of the solar cell module 5 with Cr ₂ O ₃ which is the oxide semiconductor 13, as shown in FIG. Sequentially, the oxide semiconductor 13 was immersed in a suspension of Cr ₂ O ₃ and dip-coated. This was placed on a solid honeycomb (honeycomb not coated with Cr ₂ O ₃ ), and was subjected to TASC treatment in air at 500 ° C. for 30 minutes. As a result, good results were obtained as in Example 3. Note that although a honeycomb in which an oxide semiconductor is not supported is used, a honeycomb in which an oxide semiconductor is supported may be used. In addition, a support body on which module pieces are placed may be used as long as it is not a honeycomb, but the TASC method requires sufficient oxygen to completely decompose the cut molecules into water and carbon dioxide gas. A porous support is preferred.

Example 5
In Example 4, instead of the four side surfaces of one piece of the solar cell module 5, as shown in FIG. 4B, the three sides are successively made into a suspension of Cr ₂ O ₃ that is the oxide semiconductor 13. Pickled and dip coated. This was placed on a solid honeycomb and subjected to TASC treatment in air at 500 ° C. for 30 minutes. As a result, good results were obtained as in Example 3.

Example 6
As shown in FIG. 4 (c), of the four sides of a piece of the solar cell module 5, opposite the two edges successively, _Cr 2 _{O 3} suspension of _Cr 2 _{O 3} is an oxide semiconductor 13 It was immersed in dip coating, placed on a solid honeycomb, and subjected to TASC treatment at 500 ° C. for 30 minutes in air. As a result, good results were obtained as in Example 3.

Example 7
As shown in FIG. 4 (d), one edge of the four side surfaces of one piece of the solar cell module 5 is immersed in a suspension of Cr ₂ O ₃ that is the oxide semiconductor 13 and is dip coated. This was placed on a solid honeycomb and subjected to TASC treatment in air at 500 ° C. for 30 minutes. As a result, good results were obtained as in Example 3.
Thus, it has been demonstrated that the complete decomposition of the polymer automatically proceeds to the end 120 mm away by the feature of the TASC method if the oxide semiconductor is brought into contact only on the surface of the polymer.

  As described in Example 1-7, for the TASC method, the oxide semiconductor 13 only needs to be in contact with the surface of the organic substance. Therefore, the contacting method is a method of placing the module so that the back sheet 7 of the solar cell module 5 is in contact with the honeycomb carrying the oxide semiconductor 13, and coating the suspension of the oxide semiconductor 13 on the back sheet 7. Then, either a method of placing a module on a solid honeycomb or a method of placing a module on a solid honeycomb by coating a suspension of the oxide semiconductor 13 on at least one of the four sides of the module piece may be used. However, when the suspension of the oxide semiconductor 13 is coated on the surface of the organic substance, the collected oxide (glass 1, solar battery cell 2, inter-connector 3, etc.) is mixed with a small amount of oxide semiconductor 13 powder. It is inevitable. On the other hand, in the method of placing the module so that the back sheet 7 of the solar cell module 5 is in contact with the honeycomb carrying the oxide semiconductor 13, the oxide semiconductor 13 is not mixed into the recovered material and the processing operation is extremely easy. This is a preferable method.

Example 8
Changzhou Trina Solar Energy Co. Ltd .. A solar cell panel (model: TSM-05DC80.08) was used. In this solar cell panel, the same polymer binder as that of the single base body of the solar cell module 5 was used for fixing the outer frame made of Al and the solar cell array. One piece (120 × 120 × 5 mm) of the solar cell module 5 was cut out by the method of Example 1, and the same TASC treatment as in Example 1 was performed. As in Example 1, one piece of polymer of the solar cell module 5 is completely decomposed, and from the lower layer, an inter connector 3 / a solar cell 2 / an inter connector 3 / a lump of finely cracked glass is obtained. It was. These could be easily separated. As a result of fluorescent X-ray analysis, it was found that the solar cell and the grid-like electrode material are mainly composed of silicon and silver, respectively. AgCl was recovered in the same manner as in Example 1. From 5.5 g of solar cells, 0.08 g of AgCl was recovered (1.48% by weight).

Example 9
One piece of the same solar cell module 5 was cut out from the solar cell panel used in Example 8. The same TASC treatment as in Example 8 was performed using α-Fe ₂ O ₃ (hematite) instead of Cr ₂ O ₃ used in Example 8 as the oxide semiconductor 13. As a result, good results were obtained as in Example 8.

Example 10
One piece of the same solar cell module 5 was cut out from the solar cell panel used in Example 8. Using this module piece, as in Example 3, a suspension of Cr ₂ O ₃ was coated on the back sheet 7 on the lower surface of the module by a spray coating method to about 5 to 10 microns. With this surface facing down, it was placed on a honeycomb of cordierite composition of solid (Cr ₂ O ₃ not coated) and heated in air at 500 ° C. for 30 minutes (TASC treatment). The polymer of the module piece was completely decomposed in the same manner as in Example 8, the glass, the solar battery cell 2 and the interconnector 3 were easily separated, and the grid-like silver electrode was also recovered in the form of AgCl.

Example 11
An experiment similar to that of Example 4 was performed using one piece of the solar cell module 5 of Example 8 (4-side treatment, FIG. 4A). As a result, good results were obtained as in Example 8.

Example 12
An experiment similar to that of Example 5 was performed using one piece of the solar cell module 5 of Example 8 (3-side treatment, FIG. 4B). As a result, good results were obtained as in Example 8.

Example 13
An experiment similar to that in Example 6 was performed using one piece of the solar cell module 5 in Example 8 (two-sided processing, FIG. 4C). As a result, good results were obtained as in Example 8.

Example 14
Using one piece of the solar cell module 5 of Example 8, an experiment similar to that of Example 7 was performed (one-side treatment, FIG. 4D). As a result, good results were obtained as in Example 8.

Example 15
In Example 1 or Example 2 or Example 8 or Example 9, when placing a piece of the back sheet 7 of the solar cell module 5 on the honeycomb coated with the oxide semiconductor 13, glass or the like As shown in FIG. 5, the stainless steel mesh 14 is inserted for the convenience of collecting. In advance, a groove is dug in the honeycomb so that a stainless mesh 14 having a thickness equal to or less than the groove depth can be fitted. In this way, since the oxide semiconductor 13 carried on the honeycomb contacts the surface of the back sheet 7 of the module piece, there is no problem in the TASC process, and the dismantled material is separately prepared after the TASC process. Without passing through the transfer step, the stainless steel mesh 14 and the dismantled material on the stainless steel mesh 14 are removed from the honeycomb, and the glass lump, the solar battery cell 2 and the inter connector 3 can be easily separated by the method described in the first embodiment. it can.

Example 16
In Example 3 or Example 7 or Example 10 or Example 14, when one piece of the solar cell module 5 is placed on the honeycomb on which the oxide semiconductor 13 is not supported, it is convenient to collect glass or the like. Therefore, the stainless steel mesh 14 is inserted as in the fifteenth embodiment. However, since the oxide semiconductor 13 is already applied to one piece of the solar cell module 5, there is no need to dig a groove in the honeycomb, and the stainless net 14 and one piece of the solar cell module 5 are simply formed on the honeycomb. Should be placed in the order. In this way, there is no hindrance to the TASC treatment, and the dismantled material on the stainless steel mesh 14 and the stainless steel mesh 14 is removed from the honeycomb without passing through the step of transferring the dismantled material to the separately prepared stainless steel mesh 14 after the TASC treatment. The glass lump, the solar battery cell 2 and the inter connector 3 can be easily separated by the method described in Example 1.

Example 17
In order to continuously perform the TASC processing of the solar cell module 5, it is preferable to use the TASC continuous processing device 15 for solar cell modules shown in FIG. On the honeycomb, one piece of the stainless steel mesh 14 and the solar cell module 5 is placed in this order and placed in the carrying-in portion 16 on the apparatus entrance side. When the oxide semiconductor 13-supported honeycomb is used, the honeycomb is formed by grooving according to Example 15, the stainless steel mesh 14 is placed on the honeycomb, and one piece of the solar cell module 5 is placed on the back sheet 7 below. And put it on. When the oxide semiconductor 13 is applied to the back sheet surface of one piece of the solar cell module 5 or the side surface of one piece of the solar cell module 5, stainless steel is used according to Example 16 using a honeycomb that does not carry the oxide semiconductor 13. The net 14 and one piece of the solar cell module 5 are placed. One piece of the stainless steel mesh 14 and the solar cell module 5 that are integrally formed with the honeycomb is continuously transferred at a transfer speed of about 100 mm / min by a conveyor installed from the carry-in section 16 to the carry-out section 20. Is conveyed. Air is introduced into the preheating unit 17, the TASC processing unit 18, and the cooling unit 19 from the outside. One piece of the honeycomb and the solar cell module 5 is heated to 500 ° C. while passing through the preheating unit 17. The TASC process is performed when passing through the TASC processing unit 18 which is a heat processing unit controlled to 500 ° C. over about 1000 mm, and the organic component in the module piece is completely decomposed and removed. Cooling is performed while passing through the cooling unit 19. Note that it is not necessary to cool to room temperature, and the temperature to be cooled may be appropriate. Organic matter is completely decomposed and removed from the dismantled material on the honeycomb that has come out of the cooling unit 19 by the TASC process, and the honeycomb is removed in the carry-out unit 20, so that the stainless steel mesh 14 and the dismantled material thereon are transferred to the carry-out unit 20. Returned. When sent to the sorting and collecting unit through the carry-out unit 20, the sorting and collecting unit 21 causes the white residue of the inorganic substance to fall through the mesh by the method described in the first embodiment. The glass slipped from the stainless steel mesh 14 by the first vibration and the solar battery cell 2 and the interconnector 3 slid from the stainless steel mesh 14 by the second vibration are separated and collected.

  Although it has been stated that all the routes from the carry-in part to the carry-out part are transported at a constant speed in the continuous processing device, the carry-in part, the carry-out part and the separation recovery part continuously transport the honeycomb with the solar cell module at a constant speed. The TASC processing chamber in which the preheating unit, the TASC processing unit, and the cooling unit are integrated may be a system that performs the TASC processing in a stopped state. In this case, an electric furnace having an inlet / outlet door is placed in the center in the TASC processing chamber, and when the honeycomb loaded with the solar cell module is loaded, the inlet door opens and the furnace is covered in the furnace. The workpiece is carried and the inlet is closed. After the treatment, the door on the outlet side is opened, and the dismantled material on the honeycomb subjected to the TASC treatment is carried out. This system, which is based on the batch method, is slightly complicated in transport control, but the advantages are that it is easy to manage temperature and that it can control the necessary oxygen, so that steady TASC processing is possible.

Example 18
Further, the carry-in section and the carry-out section are removed from the semi-automatic apparatus described in paragraph 46, and valuable materials can be recovered from the solar cell module by the TASC process even by a complete batch system. In FIG. 7, the solar cell module is placed in the heat treatment chamber that is the electric furnace 9 with the oxide semiconductor in contact with the solar cell module. The heat treatment chamber 9 has an air introduction port 11 and an exhaust port 12. When the heat treatment chamber 9 is heated to about 500 ° C., the organic matter in the solar cell module 5 is decomposed by the TASC treatment, and the generated high temperature gas rises. Therefore, the exhaust port 12 is provided in the ceiling of the heat treatment chamber 9. Is good. Since the gas discarded from the heat treatment chamber 9 is not completely carbon dioxide and water and may contain low molecular weight organic substances, VOC purification by the TASC method is performed outside the exhaust port 12. The device 23 is arranged. This is a device in which a plurality of honeycomb-embedded honeycomb semiconductors 8 carrying heaters are arranged in series. By heating to about 500 ° C. with a heater, the low-molecular organic matter passing through is completely carbon dioxide gas. It is decomposed into water and released into the atmosphere as a harmless gas. When the honeycomb structure 8 supporting an oxide semiconductor is disposed in the vicinity of the ceiling exhaust port 12 in the heat treatment chamber 9, the low molecular organic gas passing through the honeycomb structure 8 heated to about 500 ° C. is combined with carbon dioxide gas. Even better because it breaks down into water. A honeycomb structure 8 supporting an oxide semiconductor may be additionally provided on the side surface so as to surround the solar cell module 5. When the TASC treatment is performed by such an apparatus, the organic matter in the solar cell module 5 is completely decomposed and removed, and valuable materials can be easily recovered from the dismantled product in the electric furnace 9. In a continuous processing furnace and a semi-automatic processing furnace, it is necessary to make the apparatus very large in order to process a plurality of solar cell modules at the same time. It is possible to arrange the solar cell modules 5 side by side without difficulty, and in this way, the processing speed per sheet can be increased. The batch processing system shown in FIG. 7 is characterized by small size, low cost, and low power consumption compared to a continuous processing furnace.

  According to the present invention, glass, solar battery cells, and interconnectors, which are valuable materials, can be recovered from solar battery modules in a short time at a low cost using a semiconductor thermal activation (TASC) method. Recycling, which has not been realized in the past, can be established as a practical business for the waste of the photovoltaic power generation system that is expected to generate a large amount of processing demand, and the industrial applicability is great.

DESCRIPTION OF SYMBOLS 1 Glass 2 Solar cell 3 Inter connector 4 Polymers, such as EVA 5 Solar cell module 6 Terminal 7 Back sheet 8 Catalyst supporting honeycomb 9 Electric furnace 10 Heater 11 Air inlet 12 Exhaust port 13 Oxide semiconductor 14 Stainless steel net 15 Sun TASC continuous processing device 16 for battery modules Loading-in unit 17 Preheating unit 18 TASC processing unit 19 Cooling unit 20 Unloading unit 21 Sorting recovery unit 22 TASC processing unit 23 for solar cell module VOC purification device

Claims (16)

  The solar cell module, which is the object to be processed, is placed on the air-permeable support carrying the oxide semiconductor with the light receiving surface facing upward, so that the oxide semiconductor contacts the back sheet of the solar cell module. Then, in the presence of oxygen, the object to be processed is heated at a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region, whereby the polymer in the object to be processed is decomposed and removed, and valuable materials are recovered from the dismantled material. A method for recovering valuable materials from a solar cell module.   The back sheet of the solar cell module, which is the object to be processed, is dip coated with the oxide semiconductor suspension, thereby bringing the oxide semiconductor into contact with the back sheet of the solar cell module, The polymer in the object to be treated is decomposed and removed by heating the object to be treated at a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region in the presence of oxygen by placing it on a support having air permeability. And recovering the valuable material from the solar cell module, wherein the valuable material is recovered from the dismantled material.   One to four sides of the solar cell module, which is the object to be treated, are dip-coated with an oxide semiconductor suspension, thereby bringing the oxide semiconductor into contact with the side surface of the object to be treated, and venting the object to be treated. The polymer in the object to be processed is decomposed and removed by heating the object to be processed at a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region in the presence of oxygen. A method for recovering a valuable material from a solar cell module, wherein the valuable material is recovered from a dismantled product.   The method for recovering a valuable material from the solar cell module according to claim 1, wherein the valuable material includes any one of glass, a solar battery cell, an interconnector, or a combination thereof. After decomposing the polymer in the object to be processed and recovering valuable materials from the disassembled material,
By immersing the solar cells in the recovered material in nitric acid, the silver or silver compound that is the electrode of the solar cell is dissolved, and further, hydrochloric acid is added dropwise to produce a chloride of silver or a silver compound. The method for recovering valuable materials from the solar cell module according to claim 1, wherein silver or a silver compound is recovered. As a method of decomposing and removing the polymer in the object to be processed and recovering valuable materials from the dismantled product,
The dismantled product is transferred onto a stainless steel net, the substrate is tilted within a range of 20 degrees to 40 degrees, and is vibrated at a first frequency. First, the glass block is dropped and separated, and then at a second frequency. The method for recovering valuable materials from the solar cell module according to claim 1, wherein the solar cell and the interconnector are dropped and separated by vibration.   The solar cell module according to claim 6, wherein the first frequency is in a range of 5 Hz to 20 Hz, and the second frequency is in a range of 10 Hz to 200 Hz. How to recover. As the air-permeable support supporting the oxide semiconductor, a stainless steel net having a shape equal to the groove and having a thickness equal to or less than the groove depth is placed on a honeycomb having a plurality of grooves vertically and horizontally. Use
The method for recovering valuable materials from the solar cell module according to claim 1, wherein the object to be processed is placed on the stainless steel net and processed. As the air-permeable support, using a honeycomb on which the oxide semiconductor is not supported,
The method for recovering valuable materials from the solar cell module according to claim 2 or 3, wherein a stainless steel net is placed on the honeycomb and the object to be processed is further placed on the honeycomb. The process of decomposing and removing the polymer in the object to be processed by heating the object to be processed in the presence of oxygen is introduced into a continuous processing apparatus that conveys the support carrying the object to be processed at a constant speed. And during the period in which the oxide semiconductor in the continuous processing apparatus stays in the heat treatment unit heated to a temperature equal to or higher than the temperature that becomes the intrinsic electric conduction region,
The process of recovering valuable materials from the dismantled material is to be separated and recovered by first recovering the glass and then recovering the solar cells and the interconnector in the separation and recovery unit in the continuous processing apparatus. A method for recovering valuable materials from the solar cell module according to any one of claims 1 to 4 and claims 6 to 9.   The heat treatment unit has an exhaust port, and a VOC purification device including a gas-permeable structure carrying the oxide semiconductor is connected to the exhaust port, and the oxide semiconductor becomes an intrinsic conductive region. 11. The solar cell module according to claim 10, wherein when the structure is heated to a temperature or higher, the gas discharged from the heat treatment unit and passing through the VOC purification device is purified to a harmless gas. To recover valuable materials from In a state where the oxide semiconductor is brought into contact with the solar cell module, a conveyor that carries the air-permeable support on which the solar cell module as the object to be processed is mounted at a constant speed, and
A heat treatment unit for decomposing a polymer in the object to be processed by heating the object to be processed mounted on the air-permeable support to a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region;
An air supply mechanism for supplying air into the heat treatment unit, and a gas-permeable structure carrying the oxide semiconductor in an exhaust port for discharging gas generated in the heat treatment unit by heat treatment Are connected to each other, and the structure is heated to a temperature higher than the temperature at which the oxide semiconductor becomes an intrinsic electric conduction region, whereby the gas discharged from the heat treatment unit and passing through the VOC purification device From a solar cell module comprising a recovery unit that recovers a valuable material from a dismantled product that is purified by harmless gas and is obtained by decomposing and removing the polymer in the object to be processed in the heat treatment unit Processing equipment for recovering valuable materials.   The heat treatment unit is a treatment chamber having an inlet and an outlet for air and an inlet door and an outlet door for allowing the workpiece mounted on the air-permeable support to pass through, and from the inlet door to the workpiece. Is introduced, the entrance door is closed, the entrance door and the exit door are closed, and the polymer in the object to be processed is decomposed and removed in a state where the object to be processed is stopped. The processing apparatus for collect | recovering valuables from the solar cell module of Claim 12 characterized by the above-mentioned.   The collection unit for collecting valuable materials from the dismantled material separates and collects glass by first collecting glass, and then collecting solar cells and interconnectors. Equipment for recovering valuable materials from solar cell modules.   In a state where the oxide semiconductor is in contact with the solar cell module that is the object to be processed, the solar cell module has a heat treatment chamber in which the oxide semiconductor is intrinsic in the heat treatment chamber. By heating above the temperature that becomes the electric conduction region, the polymer in the object to be processed is decomposed, and the heat treatment chamber discharges the gas generated by the heat treatment and the air inlet for supplying air from the outside. An exhaust port is provided, and a VOC purifying device having a breathable structure carrying the oxide semiconductor is connected to the exhaust port of the heat treatment chamber, and the oxide semiconductor becomes an intrinsically conductive region. When the structure is heated to a temperature higher than the temperature, the gas discharged from the heat treatment chamber and passing through the VOC purification device is purified to a harmless gas. From polymer dismantled product obtained by decomposing removal during treatment product processing apparatus for the recovery of valuable materials from the solar cell module and recovering the valuable substance. A breathable structure carrying the oxide semiconductor is disposed near the exhaust port in the heat treatment chamber, and the structure is heated to a temperature at which the oxide semiconductor becomes an intrinsic electric conduction region. The processing apparatus for recovering valuable materials from the solar cell module according to claim 15, wherein the gas guided to the exhaust port is purified by the process.