A method for recycling waste photovoltaic modules

Abstract

This invention relates to the field of photovoltaic module recycling technology, and in particular to a method for recycling waste photovoltaic modules, comprising the following steps: S1. Pre-treating the waste photovoltaic modules by removing the junction box and aluminum frame to obtain a laminate; S2. After coarse crushing, the laminate is fed into a fluidized bed reactor, heated, and rubbed against the bed material in the reactor to de-bind and separate the glass, solar cells, solder ribbons, backsheet, and EVA binder in the laminate, resulting in a mixture, which is then discharged from the reactor through a discharge port; S3. After cooling, the mixture is sieved to classify and recycle the glass, solar cells, solder ribbons, backsheet, and EVA binder. This invention employs fluidized bed reactor debonding technology, which can quickly and effectively decompose the components of the laminate. Furthermore, the entire process is continuous, reliable, and highly efficient, with a low debonding temperature, and is unaffected by the degree of damage to the photovoltaic modules, enabling effective recycling of waste photovoltaic modules.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module recycling technology, and in particular to a method for recycling waste photovoltaic modules. Background Technology

[0002] Waste photovoltaic (PV) modules contain various components, primarily junction boxes, aluminum frames, and PV laminates. The PV laminate is a sandwich structure that bonds PV glass, crystalline silicon solar cells, and a polyvinyl fluoride (PVC) TPT backsheet together using EVA copolymer adhesive, typically connected by copper solder strips. PV module recycling involves disassembling and separating these components into individual materials for reuse in their respective processing stages. Disassembling the PV laminate is a challenging aspect of PV module recycling. Current methods for disassembling laminates include mechanical crushing, hot-blade disassembly, pyrolysis, and chemical solvent swelling. Mechanical crushing yields low purity; hot-blade disassembly is only suitable for intact PV modules and has a low success rate; pyrolysis is energy-intensive and produces difficult-to-process pyrolysis gas and tar; and chemical solvent disassembly is time-consuming. Therefore, current recycling methods suffer from drawbacks such as low recovery rates, high energy consumption, long reaction times, and the requirement for intact PV modules.

[0003] Therefore, there is an urgent need for a recycling method that is highly efficient, energy-saving, and environmentally friendly. Summary of the Invention

[0004] The purpose of this invention is to provide a method for recycling waste photovoltaic modules. This method can simply and efficiently process waste photovoltaic modules and achieve effective recycling of waste photovoltaic modules in an economical and environmentally friendly manner.

[0005] This invention provides a method for recycling waste photovoltaic modules, comprising the following steps:

[0006] S1. Pre-process the waste photovoltaic modules, remove the junction box and aluminum frame to obtain a laminate, the laminate including glass, solar cells, solder strips, backsheet and EVA adhesive;

[0007] S2. The laminate obtained in step S1 is coarsely crushed and then fed into a fluidized bed reactor for heating. The laminate is then rubbed against the bed material in the fluidized bed reactor to de-bond and separate the glass, battery cells, solder ribbons, backplate and EVA binder in the laminate to obtain a mixture. After separation, the mixture is discharged from the fluidized bed reactor through the discharge port.

[0008] S3. After cooling, the mixture obtained in step S2 is sieved to classify and recycle the glass, battery cells, solder ribbon, backsheet and EVA binder.

[0009] Preferably, in step S2, the reaction temperature of the laminated component in the fluidized bed reactor is 150-300℃, the fluidizing air velocity is 1-5m / s, and the bed material reaches a fluidized state.

[0010] Preferably, the residence time of the coarsely crushed laminate in the fluidized bed reactor is 10-30 minutes.

[0011] Preferably, the particle size of the laminate after coarse crushing in step S2 is less than 50 mm.

[0012] Preferably, the bed material is the same as the glass material in the laminate.

[0013] Preferably, the classification method in step S3 is as follows: the backsheet and EVA binder are screened out by flotation; then the solder strip is screened out by eddy current separation; and finally the glass and battery cells are separated by airflow separation or shaking table separation.

[0014] Preferably, the battery cell obtained in step S3 is further chemically treated to separate and purify silicon, silver, and aluminum elements.

[0015] Preferably, the chemical treatment method includes the following steps:

[0016] The aluminum electrode is removed by immersing the battery cell in an alkaline solution, resulting in aluminum-free battery cells and Al(OH)3.

[0017] The aluminum-free battery cell is then immersed in HNO3 solution to remove the silver electrode, resulting in a silver-free battery cell and AgNO3.

[0018] Finally, the silver-free solar cell was immersed in H3PO4 solution to remove the silicon nitride antireflection layer, yielding high-purity silicon.

[0019] The AgNO3 obtained in the above process is electrolyzed to obtain elemental silver; Al(OH)3 is pyrolyzed to obtain alumina, and the alumina is then electrolyzed to obtain elemental aluminum.

[0020] Preferably, the alkaline solution is a NaOH solution or a KOH solution.

[0021] Beneficial effects:

[0022] This invention employs fluidized bed reactor debonding technology, which can rapidly and effectively decompose the components of laminates. Moreover, the entire process is continuous, reliable, and highly efficient, with low debonding temperature and no waste gas or oil generated. It is economical and environmentally friendly, and is not affected by the degree of damage to photovoltaic modules. It can effectively recycle waste photovoltaic modules, improving the recycling efficiency and purity of photovoltaic modules. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a flowchart illustrating the process of recycling waste photovoltaic modules according to the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] Example 1

[0029] like Figure 1 As shown, a method for recycling waste photovoltaic modules includes the following steps:

[0030] S1. Pre-process the waste photovoltaic modules, remove the junction box and aluminum frame to obtain the laminate, which includes glass, solar cells, solder strips, backsheet and EVA adhesive;

[0031] S2. The laminate obtained in step S1 is fed into a crusher for coarse crushing. The particle size of the coarsely crushed laminate is less than 50mm, which facilitates subsequent conveying. The crushed laminate is then fed into a buffer bin and then into a fluidized bed reactor via a screw feeder. Hot air is supplied to the fluidized bed reactor to heat the material. The reaction temperature is 150-300℃, and the fluidizing air velocity is 1-5m / s. The hot air provides the power and heat for the fluidization of the bed material in the fluidized bed reactor, and the bed material eventually reaches a fluidized state. During the heating process, the hot air is circulated, which can effectively reduce heat loss. Preferably, the reaction temperature of the laminate in the fluidized bed reactor is 150-250℃, and the fluidizing air velocity is 2-4m / s.

[0032] The bed material is the same as the glass in the laminate. The crushed laminate can replenish the bed material, reducing the difficulty of subsequent screening of the bed material and glass, and facilitating later screening. In the fluidized bed reactor, the laminate and the fluidized bed material rub against each other, and the viscosity of the EVA binder decreases as the temperature rises. The two phases react to achieve debinding, causing the glass, battery cells, solder ribbons, backsheet and EVA binder in the laminate to debind and separate into a mixture. The residence time of the coarsely crushed laminate in the fluidized bed reactor is 10-30 minutes. The separated mixture particles are discharged from the fluidized bed reactor through the discharge port.

[0033] S3. After cooling, the mixture obtained in step S2 is sieved to separate and recycle the glass, battery cells, solder ribbon, backsheet, and EVA binder. The glass, battery cells, solder ribbon, backsheet, and EVA binder differ in shape, size, and density. The classification method is as follows:

[0034] The backsheet and EVA binder are screened out by flotation. Both the backsheet and EVA binder float during the flotation process. Since both the backsheet and EVA binder are high molecular copolymers, no further classification is required. Then, the welding strip is screened out by eddy current separation. Finally, the glass and solar cells are separated by airflow separation or shaking table separation. The separated glass can be transported back to the fluidized bed reactor as bed material, which is beneficial for the recycling of glass.

[0035] S4. The battery cells obtained in step S3 are further subjected to chemical treatment. The chemical treatment method includes the following steps:

[0036] The aluminum electrode is removed by immersing the battery cell in NaOH or KOH solution, resulting in aluminum-free battery cell and Al(OH)3.

[0037] The aluminum-free battery cell is then immersed in HNO3 solution to remove the silver electrode, resulting in a silver-free battery cell and AgNO3.

[0038] Finally, the silver-free solar cell was immersed in H3PO4 solution to remove the silicon nitride antireflection layer, yielding high-purity silicon.

[0039] The AgNO3 obtained in the above process is electrolyzed to obtain elemental silver; Al(OH)3 is pyrolyzed to obtain alumina, and the alumina is then electrolyzed to obtain elemental aluminum.

[0040] Therefore, it can be seen that silicon, silver and aluminum can be obtained by separating and purifying the solar cells.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recycling waste photovoltaic modules, characterized in that, Includes the following steps: S1. Pre-process the waste photovoltaic modules, remove the junction box and aluminum frame to obtain a laminate, the laminate including glass, solar cells, solder strips, backsheet and EVA adhesive; S2. The laminate obtained in step S1 is coarsely crushed and then fed into a fluidized bed reactor for heating. The laminate is then subjected to friction with the bed material in the fluidized bed reactor, causing the glass, battery cells, solder ribbons, backsheet, and EVA binder in the laminate to de-bond and separate into a mixture. After separation, the mixture is discharged from the fluidized bed reactor through the discharge port. The reaction temperature of the laminate in the fluidized bed reactor is 150-300℃, the fluidization velocity is 1-5m / s, and the bed material reaches a fluidized state. The bed material is made of the same material as the glass in the laminate. S3. After cooling, the mixture obtained in step S2 is sieved to classify and recycle the glass, battery cells, solder ribbon, backsheet and EVA binder. The classification method is as follows: the backsheet and EVA binder are screened out by flotation; the solder strip is then screened out by eddy current separation; and finally, the glass and battery cells are separated by airflow separation or shaking table separation.

2. The recycling method according to claim 1, characterized in that, The residence time of the coarsely crushed laminate in the fluidized bed reactor is 10-30 minutes.

3. The recycling method according to claim 1, characterized in that, In step S2, the particle size of the laminate after coarse crushing is less than 50 mm.

4. The recycling method according to claim 1, characterized in that, The battery cells obtained in step S3 are further chemically processed to separate and purify silicon, silver, and aluminum.

5. The recycling method according to claim 4, characterized in that, The chemical treatment method includes the following steps: The aluminum electrode is removed by immersing the battery cell in an alkaline solution, resulting in aluminum-free battery cells and Al(OH)3. The aluminum-free battery cell is then immersed in HNO3 solution to remove the silver electrode, resulting in a silver-free battery cell and AgNO3. Finally, the silver-free solar cell was immersed in H3PO4 solution to remove the silicon nitride antireflection layer, yielding high-purity silicon. The AgNO3 obtained in the above process is electrolyzed to obtain elemental silver; Al(OH)3 is pyrolyzed to obtain alumina, and the alumina is then electrolyzed to obtain elemental aluminum.

6. The recycling method according to claim 5, characterized in that, The alkaline solution is either NaOH or KOH.

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