Photovoltaic module cleaning and recycling method

Abstract

The invention belongs to the technical field of photovoltaic recycling, and particularly relates to a photovoltaic module cleaning and recycling method which comprises the following steps: crushing and disassembling a cleaned photovoltaic module to obtain crushed small-particle-size fragments; freezing the small fragments, crushing again, selecting first-grade fine particles after crushing, and putting the first-grade fine particles into a supercritical water oxidation instrument for EVA (Ethylene Vinyl Acetate) decomposition; the decomposed product enters a centrifugal machine to be graded, secondary coarse particles are separated out, and the secondary coarse particles are subjected to acid leaching; and grading the mixed solution after acid leaching, and screening out the silicon-containing micro-nano material and the silver-containing slurry. By introducing the process steps of mechanical disassembly, liquid nitrogen freezing, superfine grinding and the like, efficient recovery of metal silver and silicon materials in the retired photovoltaic module can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic recycling, and in particular relates to a method for cleaning and recycling photovoltaic modules. Background Art

[0002] With the rapid development of the new energy industry, the disposal of related waste has become a pressing issue. Currently, the cumulative volume of retired photovoltaic modules in my country has reached 20 million tons, but only about 10% of these modules are recycled, with the majority discarded and landfilled. The question of how to recycle these modules has become an increasingly pressing issue.

[0003] Disposal methods for retired optical components are primarily categorized as physical, chemical, and thermal. Chemical methods are difficult to implement on a large scale due to high solvent consumption, low dissolution rates, long dissolution times, and difficulty in wastewater treatment. While effective, thermal treatment methods are energy-intensive and require secondary treatment of waste gas, increasing recycling costs. Physical methods (such as mechanical pulverization, low-temperature electrostatic separation, and thermal cutting) offer lower costs and simpler processes, but they have low recovery rates and are unable to effectively recover metal materials. Furthermore, the material purity is low, making it difficult to meet reuse requirements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that it is difficult to strike a balance between efficiency, cost and environmental protection in the existing photovoltaic module recycling method.

[0005] To this end, the present invention provides a method for the clean recycling of photovoltaic modules. By incorporating mechanical disassembly, cryogenic pulverization, ultrafine grinding, liquid nitrogen freezing treatment, and supercritical water oxidation, the invention achieves efficient recovery of metallic silver and silicon materials from retired photovoltaic modules. This process not only significantly improves recovery rates and ensures high material purity, but also reduces environmental pollution and recycling costs, thereby promoting efficient resource reuse and the sustainable development of the new energy industry.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A photovoltaic module cleaning and recycling method comprising:

[0008] Crushing and disassembling cleaned photovoltaic modules to obtain small-sized fragments;

[0009] The small fragments are frozen and crushed again, and after crushing, the first-level fine particles are selected and placed in a supercritical water oxidizer for EVA decomposition;

[0010] The decomposed products are put into a centrifuge for classification to separate out secondary coarse particles, which are then acid-leached;

[0011] The mixed solution after acid leaching is classified to screen out the slurry containing silicon micro-nano materials and silver.

[0012] Furthermore, after the photovoltaic modules are crushed, they are pre-crushed by a crusher and screened by a sieve with a sieve hole diameter of 2 mm to 8 mm. The particle size of the small-sized fragments is smaller than the diameter of the sieve hole, and the large-sized fragments screened out on the sieve are put back into the crusher for crushing.

[0013] Furthermore, when freezing and crushing small particle fragments, liquid nitrogen is used for freezing, and the freezing time is 0.5 min to 2 min.

[0014] Furthermore, when the small particle fragments are frozen and crushed, an air flow mill is used for crushing, and the air flow speed of the air flow mill is 300m / s to 800m / s.

[0015] Furthermore, the fragments decomposed by EVA are separated into primary fine particles and primary coarse particles by using a hydrocyclone, wherein the diameter of the hydrocyclone is 50 mm or 75 mm and the working pressure is 0.02 MPa to 1.5 MPa.

[0016] Furthermore, the first-level coarse particles separated by the hydrocyclone are frozen, crushed, and sorted again until all the fragments are crushed into first-level fine particles.

[0017] Furthermore, the water temperature of the supercritical water oxidizer is 400° C. to 600° C. and the working pressure is 25 MPa to 35 Pa when the supercritical water oxidizer is working.

[0018] Furthermore, the decomposed products are separated into secondary fine particles and secondary coarse particles by a centrifuge, wherein the mixed liquid of the secondary fine particles is re-input into the hydrocyclone for sorting.

[0019] Furthermore, during the acid leaching process, the solid-liquid ratio of the secondary coarse particles to the acid leaching liquid is 1:2 to 1:3.

[0020] The present invention has the beneficial effect of efficiently recovering metallic silver and silicon from retired photovoltaic modules by incorporating mechanical disassembly, liquid nitrogen freezing, and ultrafine grinding, significantly improving overall recovery efficiency. By incorporating cryogenic grinding and supercritical water oxidation into the recycling process, the present invention reduces the generation of waste gas and waste liquid, avoids secondary pollution, and meets clean and environmentally friendly requirements.

[0021] The present invention adopts supercritical water oxidation technology in the recovery process, which ensures the high purity of the recovered metallic silver and silicon materials, meets the demand for material reuse, and has high recovery purity.

[0022] Compared with existing chemical methods and thermal treatment methods, the process of the present invention is simple and has low energy consumption. Through optimized processes, it reduces energy and resource consumption and lowers the overall cost of photovoltaic module recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and examples.

[0024] Figure 1 It is a schematic diagram of the implementation process of a photovoltaic module cleaning and recycling method in the present invention. DETAILED DESCRIPTION

[0025] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0028] Reference Figure 1 A method for cleaning and recycling photovoltaic modules includes the following steps. It should be noted that the "+" and "-" in the figure represent the products of the step, and the particle size of the product represented by "+" is larger than the particle size of the product represented by "-".

[0029] Step 1: Disassembly

[0030] The discarded and retired photovoltaic modules are mechanically disassembled and separated to obtain wiring boxes, aluminum frames and complete single / double glass modules.

[0031] Step 2: Pre-crushing

[0032] The obtained single / double glass components are fed into the hammer crusher for pre-crushing

[0033] Step 3: The pre-crushed product is screened using a vibrating screen. During screening, the diameter of the screen hole of the vibrating screen is 2 to 8 mm, and large-size fragments and small-size fragments are screened out.

[0034] S3.1 Return the large-size fragments to the hammer crusher for further crushing until all the fragments can pass through the sieve holes of the vibrating screen.

[0035] S3.2 The small-sized fragments are frozen and crushed by using liquid nitrogen for 0.5 to 2 minutes. The frozen small-sized fragments are crushed into ultrafine crushed products by using an air flow crusher with an air flow velocity of 300 m / s to 800 m / s.

[0036] Step 4: Classify the ultrafinely pulverized product from step S3.2. Place the ultrafinely pulverized product in a hydrocyclone with a diameter of 50 mm or 75 mm and an operating pressure of 0.02 MPa to 1.5 MPa. Extraction and water separation and classification produce first-level coarse particles and first-level fine particles.

[0037] S4.1. Place the primary coarse particles in a centrifuge for dehydration. Return the dehydrated and dried solid primary coarse particles to a liquid nitrogen freezer and freeze them according to step 3.2. Perform air flow crushing. Repeat step 4 after crushing until no primary coarse particles can be separated. Return the centrifuged suspension to the hydrocyclone.

[0038] S4.2 The first-level fine particles are fed into a supercritical water oxidizer for EVA decomposition and then reclassified.

[0039] S4.2.1. The first-level fine particles are fed into a supercritical water oxidizer for EVA decomposition. The supercritical water oxidizer operates at a water temperature of 400°C to 600°C and a working pressure of 25 MPa to 35 Pa.

[0040] S4.2.2. After treatment in the supercritical water oxidizer, the product enters the centrifuge for classification, into secondary fine particles and secondary coarse particles.

[0041] S4.2.3, the classified secondary fine particles are returned to the hydrocyclone and the operation of step S4.2 is repeated.

[0042] S4.2.4, subject the classified secondary coarse particles to acid leaching, with a solid-to-liquid ratio of 1:2 to 1:3 between the secondary coarse particles and the acid leaching solution. The leached product is filtered and classified, ultimately yielding a silver-rich slurry as the undersize product and a silicon-containing micro-nanomaterial as the oversize product.

[0043] In summary, this application, through the introduction of mechanical disassembly, liquid nitrogen freezing, and ultrafine grinding, can achieve efficient recovery of metallic silver and silicon materials from retired photovoltaic modules, significantly improving overall recovery efficiency. By introducing cryo-grinding and supercritical water oxidation processes during the recovery process, the present invention reduces the generation of waste gas and waste liquid, avoids secondary pollution, and meets the requirements of clean and environmental protection.

[0044] The present invention adopts supercritical water oxidation technology in the recovery process, which ensures the high purity of the recovered metallic silver and silicon materials, meets the demand for material reuse, and has high recovery purity.

[0045] Compared with existing chemical methods and thermal treatment methods, the process of the present invention is simple and has low energy consumption. Through optimized processes, it reduces energy and resource consumption and lowers the overall cost of photovoltaic module recycling.

[0046] In the present invention, various process parameters, such as the diameter of the vibrating screen mesh, the liquid nitrogen freezing time, the air flow mill speed, etc., are optimized and adjusted to ensure the stability and controllability of the process, and are suitable for large-scale industrial applications.

[0047] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical spirit of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for cleaning and recycling photovoltaic modules, characterized in that: include, Crushing and disassembling cleaned photovoltaic modules to obtain small-sized fragments; The small fragments are frozen and crushed again, and after crushing, the first-level fine particles are selected and placed in a supercritical water oxidizer for EVA decomposition; The decomposed products are put into a centrifuge for classification to separate out secondary coarse particles, which are then acid-leached; The mixed solution after acid leaching is classified to screen out the slurry containing silicon micro-nano materials and silver.

2. The photovoltaic module cleaning and recycling method according to claim 1, characterized in that: After the photovoltaic modules are crushed, they are pre-crushed by a crusher and screened by a sieve. The diameter of the sieve holes is 2mm to 8mm. The particle size of the small-sized fragments is smaller than the diameter of the sieve holes. The large-sized fragments screened out on the sieve are put back into the crusher for crushing.

3. The photovoltaic module cleaning and recycling method according to claim 1, characterized in that: When freezing and crushing small particle fragments, liquid nitrogen is used for freezing, and the freezing time is 0.5min to 2min.

4. The photovoltaic module cleaning and recycling method according to claim 1, characterized in that: When the small particle fragments are frozen and crushed, an air flow mill is used for crushing, and the air flow velocity of the air flow mill is 300m / s to 800m / s.

5. The photovoltaic module cleaning and recycling method according to claim 1, characterized in that: The fragments decomposed by EVA are separated into first-level fine particles and first-level coarse particles by a hydrocyclone. The diameter of the hydrocyclone is 50 mm or 75 mm, and the working pressure is 0.02 MPa to 1.5 MPa.

6. The photovoltaic module cleaning and recycling method according to claim 5, characterized in that: The first-level coarse particles separated by the hydrocyclone are frozen, crushed and sorted again until all the fragments are broken into first-level fine particles.

7. The photovoltaic module cleaning and recycling method according to claim 1, characterized in that: The water temperature of the supercritical water oxidizer is 400° C. to 600° C. and the working pressure is 25 MPa to 35 Pa when the supercritical water oxidizer is in operation.

8. The photovoltaic module cleaning and recycling method according to claim 1, characterized in that: The decomposed products are separated into secondary fine particles and secondary coarse particles by a centrifuge, wherein the mixed liquid of the secondary fine particles is re-input into the hydrocyclone for sorting.

9. The photovoltaic module cleaning and recycling method according to claim 8, characterized in that: During the acid leaching process, the solid-liquid ratio of the secondary coarse particles to the acid leaching solution is 1:2 to 1:3.

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