Disposal method for waste solar cells

Abstract

This waste solar cell processing method is for continuously processing waste solar cells, and comprises a heating step in which a solar cell module having a resin back sheet, etc. is heated in a thermal decomposition furnace so as to melt and oxidatively decompose a resin component included in a solar cell module, the method being characterized in that: the heating step is carried out by mounting the solar cell module on a porous ceramic support body (A) and moving the ceramic support body (A) through the thermal decomposition furnace from an entrance toward an exit of the furnace in a state where the ceramic support body is mounted on a porous material (B) carrying a transition metal oxide; and the thermal decomposition furnace includes, inside thereof, a temperature raising section at a stage where the temperature of the solar cell module rises, and a combustion section at a stage where the resin component oxidatively decomposes, and an oxygen concentration in the combustion section is controlled in a range of 6 vol% to less than 15 vol%.

Description

[Technical Field]

[0001] The present invention relates to a method for treating waste solar cells, and more particularly to a method for removing resin components such as backsheets and sealing resin layers from solar cell modules, separating them into glass, cells, silver, aluminum frames, etc., and recovering valuable resources. [Background technology]

[0002] Toward the realization of a low-carbon society, CO2 reductions are being accelerated through the use of renewable energy, including solar power generation. While the introduction of solar power generation has progressed significantly, the issue of recycling solar cell modules at the time of disposal has been pointed out.

[0003] A typical solar cell module has a three-layer structure: a tempered glass surface, an inner sealing resin layer, and a backsheet on the back. The sealing resin layer houses electrical wires (interconnectors) connecting the solar cell cells to each other. The sealing resin must be transparent, flexible, adhesive, tensile strength, and weather resistance. Ethylene-vinyl acetate copolymer (EVA) is commonly used, and it bonds the tempered glass, cells, and backsheet together by applying heat and pressure. When this solar cell module is heated in an electric furnace or other device under an oxidizing atmosphere, the EVA melts at 80–120°C, deacetylation of the EVA occurs at around 350°C, and rapid thermal decomposition of the polyethylene main chain occurs at around 450°C. Technologies for recycling solar cell modules using this thermal decomposition have been disclosed (see Patent Documents 1 and 2).

[0004] However, because the thermal decomposition reaction at around 450°C is explosive, thermally decomposing a solar cell module of about 1 m x 2 m could cause a fire, making it unsuitable for large-scale use. To solve this technical problem, a method for recovering solar cell element components has been disclosed (see Patent Document 3), which includes the steps of transporting the materials to a continuous heat treatment furnace in which the oxygen concentration inside the furnace is maintained at 1.0 volume % to 3.0 volume %, releasing and removing acetic acid gas, one of the EVA decomposition gases, in a preliminary thermal decomposition section set at 300 to 400°C, and then desorbing EVA decomposition gases other than acetic acid in a heat treatment section set at 400 to 550°C, removing the EVA encapsulant from the solar cell element, and separating the cell portion from the glass substrate.

[0005] Furthermore, the present applicant has proposed a method for recovering valuable materials from a solar cell module having a resin back sheet and a sealing resin layer, which includes a loading step of loading the solar cell module onto a heat-resistant porous molded body with the back sheet side facing downward, and a heating step of heating the loaded material including the solar cell module and the porous molded body in a heating furnace in an oxidizing atmosphere with an oxygen concentration of 15% or more to melt the resin component and then combust it (see Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-165150 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-59793 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-108375 [Patent Document 4] International Publication No. 2020 / 031661 [Non-patent literature]

[0007] [Non-Patent Document 1] Polymer Papers, Vol.64.No.9(2007) Summary of the Invention [Problem to be solved by the invention]

[0008] In the method presented in Patent Document 3, the oxygen concentration is controlled to be extremely low to prevent a rapid combustion reaction, and resin components such as EVA are thermally decomposed under two-stage heating conditions. However, controlling the oxygen concentration and temperature inside the furnace under the conditions of Patent Document 3 is complicated, and requires considerable skill to operate, so it cannot be said to be a simple method.

[0009] In addition, in the early days when Patent Documents 1 to 3 were filed, the material for the backsheets of solar cells was mostly weather-resistant polyvinyl fluoride (hereinafter abbreviated as "PVF"), but nowadays cheaper polyethylene terephthalate (hereinafter abbreviated as "PET") has become mainstream, and backsheets made of a single layer of PET or two- or three-layered structures laminated with PVF or a fluorine-based resin such as polyvinylidene fluoride (hereinafter abbreviated as "PVDF"), such as PVF / PET, PVDF / PET, PVF / PET / PVF, or PVDF / PET / PVDF, are also widely used, with PET accounting for the majority of backsheets.

[0010] Fluorine-based resins such as PVF and PVDF undergo thermal decomposition at temperatures similar to those of EVA, making conventional thermal decomposition methods problem-free. However, PET melts at 250°C, begins to decompose at around 400°C, and its benzene rings and ester groups result in a wide range of thermal decomposition reactions. Carbonized products, in which the benzene rings are intricately bonded together, can also be produced as by-products, resulting in the formation of pitch-black soot. Glass with soot attached to it is difficult to reuse. It has also been reported that even when burned at 850°C, only 9% of this soot remains (see Non-Patent Document 1).

[0011] Therefore, even if the technology in Patent Document 3, which reduces the oxygen concentration, can thermally decompose EVA, it does not completely decompose PET. Therefore, when a solar cell module using a back sheet containing PET is heated, it becomes covered in soot, and inorganic powders such as titanium oxide and calcium carbonate contained in the back sheet also remain, so more advanced separation technology is required to recycle valuable materials.

[0012] On the other hand, the method of Patent Document 4, by placing a heat-resistant material carrying a transition metal oxide inside a furnace, makes it possible to suppress the generation of "soot" when aromatic resins such as PET are burned, and makes it possible to easily recover valuable materials that can be reused in solar cell modules. However, when attempting to continuously heat-treat solar cell modules in an oxidizing atmosphere with an oxygen concentration of 15% or more, the temperature suddenly rises due to explosive combustion accompanied by flames, causing temperature control to swing significantly toward the upper limit, making stable treatment difficult. As a result, new issues that were not apparent in batch-type treatment were discovered, such as increased treatment costs and incomplete treatment.

[0013] Based on the above, an object of the present invention is to provide a method for continuously processing waste solar cells with stable temperature control in order to recycle valuable materials contained in solar cell modules having resin backsheets, etc. [Means for solving the problem]

[0014] The present inventors conducted extensive research to solve the above problems, and as a result, they discovered that by placing a solar cell module on a porous ceramic support, and then moving the ceramic support, which is placed on a porous material supporting a transition metal oxide, through the pyrolysis furnace from the inlet to the outlet to perform a continuous heat treatment, and by controlling the oxygen concentration in the combustion section during the oxidative decomposition of the resin component within a specific range, the resin component can be gently and stably burned and removed, thereby enabling treatment with stable temperature control, which led to the completion of the present invention.

[0015] That is, the present invention relates to a method for continuously treating waste solar cells, which includes a heating step of heating a solar cell module having a resin back sheet and a sealing resin layer in a pyrolysis furnace to melt and oxidatively decompose the resin components contained in the solar cell module, wherein the heating step is carried out by placing the solar cell module on a porous ceramic support (A), and moving the ceramic support (A) in a state where it is placed on a porous material (B) supporting a transition metal oxide, through the pyrolysis furnace from the entrance to the exit; and the pyrolysis furnace includes a temperature rising section in which the temperature of the solar cell module is increased, and a combustion section in which the resin components are oxidatively decomposed, and the oxygen concentration in the combustion section is controlled to a range of 6 vol% or more and less than 15 vol%. [Effects of the Invention]

[0016] In this invention, the resin components such as EVA and PET melt before ignition permeate the heat-resistant porous molded body, expanding the surface area and allowing for gentle combustion, preventing sudden combustion reactions and ensuring stable combustion. Furthermore, it is possible to suppress the generation of soot when aromatic resins such as PET are burned, making it easy to recover valuable materials that can be reused in solar cell modules. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram (with aluminum frame) showing one embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing one embodiment of the present invention (without an aluminum frame). [Figure 3] FIG. 1 is a schematic diagram illustrating an outline of a pyrolysis furnace used in Examples and Comparative Examples. [Figure 4] 1 is a graph showing changes in furnace temperature and oxygen concentration in an example and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below. The method for treating waste solar cells according to the present invention is a method for continuously treating waste solar cells, comprising a heating step of heating a solar cell module having a resin back sheet and an encapsulating resin layer in a pyrolysis furnace to melt and oxidatively decompose a resin component contained in the solar cell module, the heating step is carried out by placing the solar cell module on a porous ceramic support (A), and moving the ceramic support (A) in a state where the ceramic support (A) is placed on a porous material (B) supporting a transition metal oxide within the pyrolysis furnace from the inlet to the outlet of the furnace; and The pyrolysis furnace includes a temperature rising section where the temperature of the solar cell module rises, and a combustion section where the resin component is oxidatively decomposed, and the oxygen concentration in the combustion section is controlled to a range of 6 vol% or more and less than 15 vol%.

[0019] <Heating process> The heating step in the treatment method of the present invention is a step in which a solar cell module having a resin backsheet and an encapsulating resin layer is heated in a pyrolysis furnace to melt and oxidatively decompose the resin components contained in the solar cell module.

[0020] In the heating step, the solar cell module is placed on a porous ceramic support (A), and the ceramic support (A) is placed on a porous material (B) carrying a transition metal oxide (see FIG. 1 ), and the ceramic support (A) is then moved through the pyrolysis furnace from the entrance to the exit. It is preferable to place the solar cell module on the ceramic support (A) with the backsheet facing downward. To improve the efficiency of waste solar cells, it is preferable to continuously move multiple solar cell modules so that multiple solar cell modules are heated in the pyrolysis furnace. When heat-treating the treated object consisting of the solar cell module, ceramic support (A), and porous material (B), the treated object may be placed on an iron tray with a grid to prevent the objects from collapsing or tipping over during transport through the furnace.

[0021] In the heating step, the interior of the pyrolysis furnace includes a temperature-raising section where the temperature of the solar cell module rises, and a combustion section where the resin component is oxidatively decomposed (combusted). Normally, the inlet side of the pyrolysis furnace is the temperature-raising section, and the outlet side is the combustion section, but as long as the temperature rises as the solar cell module moves from the inlet side to the outlet side of the furnace, and the resin component melts and is oxidatively decomposed, the boundary between the temperature-raising section and the combustion section in the pyrolysis furnace does not need to be clear.

[0022] In the present invention, combustion refers to an oxidation reaction in which organic materials such as EVA and PET contained in the backsheet and sealing resin layer constituting the solar cell module react with oxygen in the atmosphere.

[0023] Therefore, the combustion temperature is determined appropriately depending on the resin that constitutes the backsheet, but is preferably 425 to 575°C. If the temperature is 425°C or higher, it will be higher than the thermal decomposition temperature of EVA and PET and will cause combustion. If the temperature is 575°C or lower, rapid combustion can be suppressed, preventing damage to the glass of the solar cell module.

[0024] The melting begins at a temperature lower than the combustion temperature. To reach the combustion temperature, the temperature of the solar cell module is generally raised from room temperature before entering the pyrolysis furnace, and the melting temperature can be reached during this temperature increase process.

[0025] The heating in the heating step should be carried out in a pyrolysis furnace, taking into consideration the treatment of exhaust gas, etc. The pyrolysis furnace is not particularly limited as long as it can obtain the combustion temperature and can be a gas furnace, electric furnace, or the like, into which the porous material (B), the ceramic support (A), and the workpiece including the solar cell module can be charged, and any known pyrolysis furnace can be used.

[0026] The method for heating the interior of the pyrolysis furnace is not particularly limited as long as the combustion temperature can be obtained, but in the case of a gas furnace, for example, an oxygen-containing gas is heated with a gas burner or the like and circulated within the pyrolysis furnace. Examples of the oxygen-containing gas include a mixed gas of a combustible gas such as LP gas or city gas with air.

[0027] In the heating step, by controlling the oxygen concentration in the combustion zone to a range of 6 vol% or more and less than 15 vol%, the resin components can be gently and stably burned and removed. The lower limit of the oxygen concentration is preferably 7 vol%, more preferably 8 vol%, and the upper limit is preferably 14.8 vol%, more preferably 14.5 vol%. Even if the oxygen concentration momentarily deviates from the range, this does not pose any particular operational problem as long as it can be quickly controlled to the range.

[0028] The method for controlling the oxygen concentration in the combustion section is not particularly limited. For example, in the case of a gas furnace using a mixture of LP gas and air as the oxygen-containing gas, the air mixing ratio can be adjusted according to the oxygen concentration in the combustion section.

[0029] In the method of the present invention, it is preferable to recover valuable materials remaining on the ceramic support (A) after the heating step. The valuable materials are preferably at least one selected from the group consisting of glass, cells, silver, aluminum frames, etc. The silver is derived from, for example, electrodes, etc.

[0030] In the method of the present invention, in order to efficiently recover the valuable materials, it is also effective to install a wire mesh or the like between the solar cell module and the ceramic support (A) before the heat treatment so as not to prevent the resin molten during combustion from moving to the ceramic support (A), and recover the valuable materials together with the wire mesh after the treatment. This is because the treated material after the resin sealing band is melted and burned will be in a state where the glass, cells, etc. are scattered on the ceramic support, making recovery difficult.

[0031] <Solar cell module> The solar cell module applicable to the present invention can be any solar cell module having a resin backsheet that is not a double-sided glass type. Specific examples include monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, heterojunction solar cells, CIS solar cells, CIGS solar cells, and CdTe solar cells. Regarding the aluminum frame of the solar cell module, the aluminum frame may be removed before pyrolysis, which has the advantage of simplifying the process by eliminating the need to cut the ceramic support (A) to fit the size of the aluminum frame. Alternatively, the aluminum frame may be removed after pyrolysis to reduce the possibility of the glass breaking during removal.

[0032] <Ceramic support (A)> The porous ceramic support (A) applicable to the present invention can be any material that is stable at the combustion temperature (specifically, about 425°C to 575°C) described below and has a porous structure. Specific examples of such materials include stable and common ceramic materials such as alumina, zirconia, silicon nitride, silicon carbide, cordierite, ferrite, barium titanate, lead zirconate titanate, forsterite, zircon, mullite, steatite, and aluminum nitride.

[0033] There are no particular restrictions on the pore size of the porous material, but a size of about 0.1 to 5 mm is preferred, as this allows for easy penetration when EVA, PET, etc. are melted at around 450°C. There are no particular restrictions on the number of cells on the surface, but 5 to 50 pixels per inch (hereinafter abbreviated as "ppi") is preferred. There are also no particular restrictions on the porosity, but a porosity of about 50 to 95% is preferred. In particular, materials with a three-dimensional skeletal structure of interconnected pores are preferred.

[0034] The shape of the ceramic support (A) is not particularly limited, but a plate-shaped one is preferably used so that the resin used in the solar cell does not fall. Furthermore, from the viewpoint of suppressing the generation of "soot" due to leakage of molten resin components to the outside of the ceramic support (A), the size (area) of the surface of the ceramic support (A) on which the back sheet is placed is preferably as large as possible within the range that can be accommodated within the aluminum frame when the aluminum frame is not removed (see Figure 1), and is preferably larger than the bottom area of the back sheet when the aluminum frame is removed from the solar cell module (see Figure 2).

[0035] There is no limitation on the thickness of the ceramic support (A), but a thickness of about 10 to 60 mm is preferred.

[0036] As the ceramic support (A) as described above, ceramic foams made of alumina, silicon carbide and cordierite, ceramic filters or products called ceramic foam filters are suitable.

[0037] When waste solar cells are treated by the method of the present invention, the solar cell module is placed on the ceramic support (A) with its back sheet facing downwards. By placing the back sheet facing downwards, the resin components constituting the back sheet and the encapsulating resin layer are melted by heating and then flow out toward the ceramic support (A) by the action of gravity.

[0038] Since the ceramic support (A) is porous, the resin that flows down has a large contact area with the atmosphere in the pyrolysis furnace, which increases the efficiency of combustion due to further heating and suppresses the generation of soot.

[0039] <Porous material (B)> In the porous material (B) carrying a transition metal oxide used in the present invention, the transition metal oxide adsorbs oxygen in an oxidized state and has the ability to decompose organic compounds having aromatic rings that are produced by the oxidative decomposition of aromatic resins during combustion. For example, chromium (III) oxide is in a reduced state and is bright green at room temperature, but when heated to 400°C or higher in the presence of oxygen, it adsorbs oxygen and changes color to black-green, indicating its oxidized state.

[0040] The inventors discovered that when a ceramic support similar to the ceramic support (A) (e.g., a ceramic filter) was coated with chromium (III) oxide and placed in a furnace, almost no soot was generated on the ceramic filter. This is thought to be because the organic compounds having aromatic rings were decomposed by the transition metal oxide, suppressing the generation of soot. It was found that the same phenomenon occurs with iron (III) oxide, copper (II) oxide, titanium (IV) oxide, etc.

[0041] For the above reasons, when at least a portion of the resin constituting the backsheet is an aromatic resin (a resin having an aromatic group as part of the repeating unit) such as PET, it is preferable to have the transition metal oxide present in the furnace in order to suppress the generation of soot.

[0042] Examples of the transition metal oxide that can be used include, without any limitation, oxides of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, and mercury.

[0043] Among these, oxides of first transition elements such as scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, and copper are preferred, oxides of second transition elements such as yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, and silver, and oxides of third transition elements such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and gold are preferred, and transition metal oxides such as rutile or anatase titanium(IV) oxide, chromium(III) oxide, iron(III) oxide, and copper(II) oxide are more preferred. These may be in the form of composite oxides.

[0044] In order to increase the contact area, it is preferable that the transition metal oxide is supported on a porous material (B) and placed in the furnace. The porous material (B) may be made of a similar material as the ceramic support (A), as long as it is stable at the combustion temperature of the resin component. The shape of the porous material (B) is not particularly limited as long as it can be used as a catalyst support, but it is more preferable that it be a plate-shaped porous molded body similar to the ceramic support (A) on which the solar cell module is mounted.

[0045] The transition metal oxide can be supported on a porous material by any known technique without any limitations. Specifically, a common method involves impregnating a porous material with a solution containing the transition metal oxide by dip coating, wash coating, spray coating, spin coating, or the like. The simplest method is to then remove the solution by heating it to a temperature above the boiling point of the solution. Alternatively, a thermal spraying technique may be used in which a molten transition metal oxide is sprayed onto the porous material.

[0046] In the present invention, the ceramic support (A) on which the solar cell module is mounted is placed on the porous material (B) carrying the transition metal oxide.

[0047] It is preferable to arrange the porous material (B) carrying a transition metal oxide so that it does not come into direct contact with the solar cell module, and it is particularly preferable to arrange it below the solar cell module so that it does not come into direct contact with the solar cell module. This is because this makes it difficult for the porous material (B) to be contaminated by non-combustible components such as fillers contained in the back sheet of the solar cell module, and eliminates the need for regeneration treatment when the porous material (B) carrying a transition metal oxide is used repeatedly.

[0048] Regarding the size of the porous material (B), from the viewpoint of the stability of the object to be treated, including the solar cell module, it is preferable that the loading surface of the porous material (B) is equal to or larger than the bottom area of the ceramic support (A).The thickness of the porous material (B) is preferably about 10 to 60 mm. [Example]

[0049] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples in any way.

[0050] [Example 1] Using a pyrolysis furnace 20 as shown in Figure 3, the heat treatment was carried out by moving the object to be treated 23 including the solar cell module 7 within the furnace using a chain conveyor 24 from the left side (entrance side) of the pyrolysis furnace section 22 to the right side (exit side). The experiment was conducted using an "REC Solar Panel" manufactured by REC (cell type: REC PE polycrystalline solar cell, size: 1,665 mm x 991 mm x 38 mm) as the solar cell module 7. The aluminum frame 10, junction box, and connectors were removed using a scraper and hammer before the heat treatment, taking care not to scratch the glass.

[0051] The ceramic filter used as the ceramic support (A) 2 was FCF-2 (made of silicon carbide) manufactured by Seisen Filter, 10 ppi, 400 mm x 300 mm x 30 mm (porosity 87.8%).

[0052] Wako Grade 1 chromium (III) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was suspended in water and stirred, and the ceramic filter was immersed in the suspension to perform dip coating, followed by drying at 450°C to obtain porous material (B) 1. The mass before coating was 1,480 g, and the mass after coating and drying was 1,790 g.

[0053] A 2,100mm x 1,210mm x 50mm iron tray with a grid was fabricated, and 21 chromium oxide-coated ceramic filters were used to place a 2,100mm x 1,200mm x 30mm porous material (B) 1 on the bottom layer. A 2,100mm x 1,200mm x 30mm ceramic support (A) 2 was placed on the middle layer above that, using 21 400mm x 300mm x 30mm ceramic filters. The solar cell module 7 was then placed on top of that, with the backsheet 3 facing downwards.

[0054] A gas furnace was used as the pyrolysis furnace 20. The gas furnace used was a hot air circulation type heat treatment device with a tactile feed chain blow type furnace length of 5,400 mm, an inner furnace width of 2,300 mm, and an inner furnace height of 280 mm. A metallic burner MJPE-200K was used in the gas burner section 21, and a mixture of LPG and air was burned and heated. The heated mixture gas was then passed through an Adachi Kiko "6.0-LF limit load fan" (450 m 3 The gas was supplied from the lower side of the pyrolysis furnace section 22 through a slit at a pressure of 1 / min, 2.0 kPa, 30 kW, and vigorously sprayed onto the porous material (B) 1 to allow heat exchange, and a part of the circulated heated gas was exhausted.

[0055] The workpiece 23 prepared as described above, consisting of the solar cell module 7, ceramic support (A) 2, and porous material (B) 1, was tact-fed from the entrance side to the exit side of the pyrolysis furnace section 22 through three sections of the furnace, each held for 6.5 minutes, for a total of 19.5 minutes, and was heat-treated in the pyrolysis furnace 20. The entrance side is the temperature-raising section 27, and the zone where the resin component contained in the solar cell module 7 burns is the combustion section 28. A thermocouple thermometer was inserted into the center of the top of the ceramic support (A) 2 in the middle section, to measure the temperature of the workpiece 23.

[0056] For the heat treatment, the proportion of air in the supplied mixed gas was adjusted so that the oxygen concentration in the combustion section 28 measured by the oxygen concentration measuring section 26 was in the range of 6 vol% or more and less than 15 vol%, and the heating temperature and supply amount of the supplied mixed gas were adjusted so that the temperature of the workpiece 23 in the combustion section 28 was 470°C or more.

[0057] As a result of the heat treatment performed as described above, as shown in Figure 4, by controlling the oxygen concentration in the combustion section 28 during the heat treatment to a range of 6 vol% or more and less than 15 vol%, the temperature inside the furnace could be stably controlled in the range of 470 to 530°C. In other words, it was found that stable temperature control and treatment of the workpiece 23 are possible through gentle combustion without flames in a low-oxygen atmosphere. After the heat treatment, the tempered glass 6 was recovered without breaking, and the cells 5 and inorganic powder were also recovered. Furthermore, no soot was observed adhering to the bottom ceramic filter used as the porous material (B) 1.

[0058] [Comparative Example 1] Heat treatment of the workpiece 23 including the solar cell module 7 was carried out in the same manner as in Example 1, except that the oxygen concentration in the combustion section 28 was changed to 15 vol% or higher by the oxygen concentration measurement section 26. As a result, as shown in Fig. 4, the temperature inside the furnace rose sharply due to explosive combustion accompanied by flames, and measures such as reducing the supply amount of the supply gas were required. In other words, it was found that it is difficult to stably control the temperature inside the furnace under a normal oxygen atmosphere, which results in an increase in treatment costs. [Explanation of symbols]

[0059] 1: Porous material carrying transition metal oxide (B) 2: Porous ceramic support (A) 3: Back seat 4: Sealing resin layer (EVA) 5: Cell 6: Tempered glass 7: Solar cell module (X) 8: Shelf or wire mesh 9: Gas or electric furnace 10: Aluminum frame 20:Pyrolysis furnace 21: Gas burner section 22: Pyrolysis furnace part 23: Processing object 24: Chain conveyor 25:Temperature measurement part 26: Oxygen concentration measurement unit 27: Temperature rising section 28: Combustion section

Claims

1. A method for continuously processing waste solar cells, comprising a heating step of heating a solar cell module having a resin back sheet and an encapsulating resin layer in a pyrolysis furnace to melt and oxidatively decompose a resin component contained in the solar cell module, the heating step is carried out by placing the solar cell module on a porous ceramic support (A), and moving the ceramic support (A) in a state where the ceramic support (A) is placed on a porous material (B) supporting a transition metal oxide within the pyrolysis furnace from the inlet to the outlet of the furnace; and A method for processing waste solar cells, characterized in that the pyrolysis furnace includes a temperature rising section in which the temperature of the solar cell module increases and a combustion section in which the resin component is oxidatively decomposed, and the oxygen concentration in the combustion section is controlled to a range of 6 vol% or more and less than 15 vol%.

2. The method for treating waste solar cells according to claim 1 , wherein a plurality of the solar cell modules are present in the pyrolysis furnace under heating.

3. 3. The method for treating waste solar cells according to claim 1, further comprising recovering valuable materials remaining on the ceramic support (A) after the heating step.

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