Method for low-temperature interface dissociation of retired crystalline silicon photovoltaic modules and high-value material grading recovery

Abstract

The application discloses a method for low-temperature interface dissociation and high-value material graded recovery of decommissioned crystalline silicon photovoltaic modules, comprising the following steps: S1, pretreatment; S2, opening treatment; S3, directional activation; S4, thermal auxiliary softening; S5, flexible peeling; and S6, graded recovery. The application adopts the coupling technology of interface activation and low-temperature thermal auxiliary softening, does not depend on high-temperature complete pyrolysis, significantly reduces energy consumption and pollution release risk, carries out layered peeling first, and then carries out material graded recovery, avoids glass, silicon wafer and metal mixing caused by direct crushing, can improve glass complete recovery rate, silicon wafer recoverable rate and silver copper recovery efficiency, integrates EVA detachment, material peeling, silver copper silicon collaborative recovery and pollution control into a complete process system, the process flow can be modularly designed, is suitable for large photovoltaic base surrounding regionalization processing and mobile pretreatment unit construction, and meets the needs of large-scale, low-carbonization and resourceization processing.

Description

Technical Field

[0001] This invention relates to the field of resource utilization technology for decommissioned new energy equipment, specifically to a method for low-temperature interface dissociation and graded recycling of high-value materials from decommissioned crystalline silicon photovoltaic modules. Background Technology

[0002] With the rapid development of the photovoltaic industry, a large number of crystalline silicon photovoltaic modules will enter the concentrated retirement phase in the future. Crystalline silicon photovoltaic modules are typically composed of aluminum alloy frames, tempered glass, EVA encapsulation film, solar cells, silver electrodes, solder strips, copper strips, backsheets, junction boxes, and cables. Among them, the EVA film firmly bonds the glass, solar cells, and backsheet, forming a multi-layered composite structure, which makes the disassembly of retired modules quite difficult.

[0003] Existing methods for processing retired photovoltaic modules mainly include mechanical crushing, high-temperature pyrolysis, chemical dissolution, and wet metal recycling. Mechanical crushing is simple, but it results in a mixture of glass, silicon wafers, metals, and encapsulation materials, making subsequent sorting difficult and reducing resource value. High-temperature pyrolysis can remove EVA encapsulation materials, but it is usually energy-intensive, and EVA and fluorinated backsheets may release volatile organic compounds, fluorinated gases, and particulate matter at high temperatures. Chemical dissolution can reduce the adhesion strength of encapsulation materials, but it involves large amounts of solvent, complex wastewater treatment, and the risk of secondary pollution. Wet recycling can recover metals such as silver and copper, but if the front-end separation is insufficient, it can easily lead to metal loss and complicate the leaching system.

[0004] Patent application CN121820301A discloses a method and its modular system for the full-component recovery of decommissioned photovoltaic modules using atmospheric pressure low-temperature pyrolysis. This process utilizes particulate combustion materials in the furnace, is equipped with a temperature control device, and does not use electric heating wires or direct electricity. It is described as economical, energy-saving, and safe, using electricity only for auxiliary equipment and lighting. The entire process generates no harmful substances or gases, and the recovery process is considered reasonable and cost-effective. It claims to solve a series of problems in the recycling process of decommissioned photovoltaic modules, achieving full-component recovery, and that the complete pyrolysis system is highly efficient and suitable for large-scale recycling of decommissioned photovoltaic modules. However, this patent is essentially still a pyrolysis method, using EVA pyrolysis and gasification as the main separation method. Although it uses low temperature, it still relies on combustion heating, and cannot avoid the risk of VOCs and fluorine-containing gas release during the pyrolysis process.

[0005] Therefore, especially in regions with a wide distribution of large photovoltaic bases, large transportation radii, and a large number of retired modules in the future, there is an urgent need to develop a green dismantling and high-value material recycling method for retired photovoltaic modules that is low in energy consumption, low in pollution, low in damage, and modularly deployable. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for low-temperature interface dissociation and graded recycling of high-value materials from decommissioned crystalline silicon photovoltaic modules.

[0007] The technical solution of this invention is: A method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules includes the following steps: S1. Pre-processing: Remove the aluminum frame, junction box and cables of the retired crystalline silicon photovoltaic module to obtain the main laminate; S2. Opening treatment: The main laminate is opened at the edges by physical cutting to expose the EVA encapsulation layer interface. S3. Targeted activation: The interface activation medium is penetrated along the interface between the EVA encapsulation layer and each material layer by means of spraying, circulating rinsing or soaking, so as to reduce the interfacial adhesion strength between the EVA encapsulation layer and each material layer. S4. Heat-assisted softening: The EVA encapsulation layer after directional activation is subjected to low-temperature heat-assisted softening at 120~220℃ for 10~30min. S5. Flexible peeling: The EVA encapsulation layer after heat-assisted softening is flexibly peeled off to separate the glass layer, EVA residual film, backsheet layer, battery cell layer and metal components. S6. Graded recycling: The battery cell layers and metal components are graded and recycled for silver, copper and silicon.

[0008] Furthermore, in S1, the retired crystalline silicon photovoltaic module is a monocrystalline silicon module, a polycrystalline silicon module, a single-glass module, a double-glass module, a crystalline silicon module with a backsheet, or a crystalline silicon module with a fluorine-containing backsheet.

[0009] Note: The method of this invention is applicable to various types of photovoltaic modules, and has strong versatility and wide adaptability.

[0010] Furthermore, before executing S1, pre-classification is also included, dividing components into low-damage components, medium-to-high-damage components, and severely damaged components. The corresponding processing route is determined based on the pre-classification results. (1) Criteria for judging low-damage components: A module is classified as a low-damage module if it meets all of the following conditions: the broken glass area accounts for less than 5% of the total area of ​​the module, and the broken area is located outside the area directly above the solar cells; the backsheet is free of powdering, cracking, and delamination; the module power degradation rate is less than 20%; and the module surface is free of severe dust accumulation, oil stains, and acid corrosion marks. For low-damage components, the processing route is: execute S1~S6; (2) Criteria for determining medium to high damage components: A module is classified as a medium-to-high damage module if it meets any of the following conditions: the broken glass area accounts for 5% to 30% of the total area of ​​the module; or the broken glass is located directly above the solar cell and has caused the solar cell to be exposed; or the broken glass has caused obvious water ingress inside the module. For medium to high damage components, the processing route is as follows: after executing S1, first scrape off the broken glass layer and wipe the exposed cell layer clean, and then execute S2~S5. (3) Criteria for determining severely damaged components: A module is deemed severely damaged if it meets any of the following conditions: the broken glass area accounts for more than 30% of the total area of ​​the module; or more than 20% of the cells are obviously broken or missing; or the backsheet has a large area of ​​pulverization, cracking, delamination or detachment, and the pulverized area exceeds 50% of the total area of ​​the backsheet; or the backsheet is a fluorine-containing backsheet and has obviously yellowed or become embrittled; or the module has been in service for more than 20 years and the power degradation rate exceeds 30%; or the module surface has obvious acid corrosion, hot spot burning or fire marks. For severely damaged components, the processing route is as follows: after executing S1, the main laminate is directly fed into the crushing equipment for mechanical crushing. After crushing, the metal components, glass materials and silicon materials are screened out and then enter the graded recycling of silver, copper and silicon in S6.

[0011] Explanation: By classifying and categorizing components, components with different degrees of damage and aging conditions can be sent to the most suitable processing routes, thereby improving overall processing efficiency and material recovery rate, and avoiding reagent waste and equipment idleness.

[0012] Furthermore, in S2, the physical cutting includes mechanical cutting, hot knife edge cutting, laser scribing, or localized grinding. Mechanical cutting is suitable for the low-breakage components, using a circular saw to cut along the edge of the main laminate at a distance of 2-5 mm. Hot knife edge cutting is suitable for the fluorine-containing main laminate, with a hot knife heating temperature of 200-300℃ and a cutting depth of 1-3 mm. Laser scribing is suitable for the low-breakage components or medium-to-high-breakage components, with a laser power of 30-100W and a cutting depth of 0.5-2 mm. Localized grinding is suitable for the medium-to-high-breakage components, using a grinding wheel to grind along the edge of the main laminate, with a grinding depth of 0.5-2 mm and a grinding wheel speed of 3000-5000 rpm.

[0013] Note: Different physical cutting methods are selected for different component types and degrees of damage, balancing opening efficiency and component protection, and avoiding excessive cutting that could damage the internal cells.

[0014] Furthermore, in S3, the activation temperature is 40~90℃, and the activation time is 10~120 min. For the low-damage component, a spraying or circulating rinsing method is used, and the flow rate of the interface activation medium is 5~20 L / min·m. 2 The spray pressure is 0.2~0.8MPa; for the medium and high damage components, the EVA encapsulation layer is completely immersed in the interface activation medium by immersion, and the volume ratio of the interface activation medium to the EVA encapsulation layer is 3~10:1.

[0015] Note: The application method of the activation solution can be matched according to the different degrees of damage, reducing the amount of activation solution used by more than 30% and improving the activation efficiency.

[0016] Furthermore, in S3, the interface activation medium is an alcohol-based medium, an ester-based medium, a weakly alkaline aqueous solution, a surfactant compound solution, or a water-based green swelling system; the pH of the interface activation medium is 7-11; and the mass concentration of the interface activation medium is 0.1-75%. For the low-damage components, alcohol-based or ester-based media are selected; for medium- to high-damage components, surfactant-based compound solutions are selected; for the fluorine-containing main laminate, weakly alkaline aqueous solutions or water-based green swelling systems are selected. The alcohol medium is anhydrous ethanol, n-butanol, or isopropanol; the ester medium is ethyl acetate; the weakly alkaline aqueous solution is sodium hydroxide aqueous solution or sodium carbonate aqueous solution; the surfactant compound solution is fatty alcohol polyoxyethylene ether or alkyl glycoside; and the water-based green swelling system is prepared by menthol-decanoic acid in a 1:1 mass ratio.

[0017] Note: Different activation media are selected for different component types to achieve a balance between activation efficiency and environmental friendliness.

[0018] Furthermore, in S4, the low-temperature heat-assisted softening method includes hot air, infrared or microwave, wherein the infrared wavelength is 1070nm and the microwave power is 150~400W.

[0019] Note: Multiple heating methods are available to adapt to different production scenarios and flexibly match regional processing needs.

[0020] Furthermore, in S5, the flexible peeling methods include hot knife peeling, roller peeling, vacuum adsorption peeling, or ultrasonic-assisted peeling. Among them, the blade temperature of hot knife peeling is 280~300℃, the roller pressure of roller peeling is 0.2~0.5MPa, the vacuum degree of vacuum adsorption peeling is maintained at -60~-90kPa, and the ultrasonic power of ultrasonic-assisted peeling is 720~800W, and the ultrasonic frequency is 28~40kHz.

[0021] Note: Multiple flexible peeling methods are provided, allowing you to select the most suitable peeling method for different component conditions, ensuring a glass integrity rate of ≥90%.

[0022] Furthermore, in S6, the graded recycling method for silver involves firstly subjecting the battery cell layers obtained from flexible peeling to low-temperature heat treatment at 300-500°C for 30-120 minutes to remove residual EVA and organic matter from the backsheet; then, thoroughly washing with an alkaline solution (sodium hydroxide or potassium hydroxide solution with a concentration of 1-10 wt%) to remove the aluminum backsheet surface of the battery cells; subsequently, thoroughly washing the alkaline-washed battery cell layers with an acidic solution (dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid with a pH of 1-10%) to remove the oxide layer and impurities from the surface of the silver electrodes. 3; Subsequently, the acid-washed battery wafer layers are selectively leached with silver using a nitric acid solution, allowing silver to enter the leaching solution in ionic form, thus achieving solid-liquid separation between silver and silicon wafers. The molar concentration of the nitric acid solution is 3~5 mol / L, and the liquid-to-solid ratio is 4~5 mL:1 g. The mixture is stirred at 65~70℃ for 45~60 min. The solid-liquid separation yields a silver-containing leaching solution, which is then subjected to reduction precipitation using ascorbic acid as the reducing agent. The molar ratio of ascorbic acid to silver ions is 1~2:1. The reaction is stirred at pH 3.5~4.5 and temperature 30~50℃ for 30~60 min. After solid-liquid separation, washing, and drying, metallic silver powder is obtained. The graded recovery method for copper involves mechanically separating the copper solder strip and cable from the metal component to obtain copper strip. The copper strip is then placed in a mixed solution of 5-7 mol / L acetic acid and 0.5-0.75 mL / L hydrogen peroxide, with a liquid-to-solid ratio of 5-10 mL:1 g. The reaction is carried out at 40-60°C for 30-60 min, allowing the lead-tin plating to selectively dissolve while the copper substrate remains insoluble. After solid-liquid separation, high-purity copper strip is obtained. The graded recycling method for silicon involves placing the silicon material or the remaining silicon-containing material in the battery cell layer and the metal component into a hydrochloric acid solution for acid washing to remove residual metal impurities and metal oxides on the surface of the silicon material. The mass fraction of hydrochloric acid is 5-15%, the liquid-to-solid ratio is 5-10 mL:1 g, and the reaction is carried out at 30-50°C for 20-60 min. After acid washing, solid-liquid separation is performed, and the obtained silicon material is placed into a sodium hydroxide solution for alkaline etching to remove the silicon nitride antireflective layer and residual aluminum impurities on the surface of the silicon wafer. The molar concentration of sodium hydroxide is 1-2.5 mol / L, and the reaction is carried out at 40-60°C for 10-30 min, with a liquid-to-solid ratio of 5-10 mL:1 g. After alkaline etching, solid-liquid separation is performed, and the obtained silicon material is repeatedly washed with deionized water until neutral, and then dried to obtain recycled silicon material.

[0023] Note: By further refining the graded recycling method, we can achieve efficient graded recycling with silver recovery rate ≥85%, copper recovery rate ≥90%, and silicon purity of 4N grade, and waste liquid recycling rate ≥70%.

[0024] The beneficial effects of this invention are: (1) This invention adopts interface activation and low temperature thermal-assisted softening coupling technology, which does not rely on high temperature complete pyrolysis, significantly reducing energy consumption and pollutant release risks. First, layered stripping is carried out, and then material graded recycling is carried out to avoid the mixing of glass, silicon wafers and metals caused by direct crushing. It can improve the glass integrity recycling rate, silicon wafer recyclability rate and silver and copper recycling efficiency. EVA desorption, material stripping, silver, copper and silicon synergistic recycling and pollution control are incorporated into a complete process system. The process flow can be modularly designed and is suitable for the regional treatment around large photovoltaic bases and the construction of mobile pretreatment units, as well as the needs of large-scale, low-carbon and resource-based treatment.

[0025] (2) By classifying and classifying components, the present invention allows components with different degrees of damage and aging to enter the optimal processing route, thereby improving the overall processing efficiency and material recovery rate, avoiding reagent waste and equipment idleness. With three routes running in parallel, the overall processing efficiency is increased by 20% to 30%, and the operating cost is reduced by about 25% to 40%. It also avoids the interference of inferior components on the main process: if glass fragments and aged back plates of severely damaged components enter the main process, it may cause the stripping equipment to jam, the activation liquid to be contaminated, and the tail gas treatment load to increase. Classification and processing avoids these problems from the source. Attached Figure Description

[0026] Figure 1 This is a schematic diagram comparing the glass integrity recovery rates of various cases in the experimental examples of this invention; Figure 2 This is a schematic diagram comparing the silver recovery rates of various cases in the experimental examples of this invention; Figure 3 This is a schematic diagram comparing the copper recovery rates of various cases in the experimental examples of this invention; Figure 4 This is a schematic diagram comparing the silicon recovery rates of various cases in the experimental examples of this invention. Detailed Implementation

[0027] Example 1: A method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules, comprising the following steps: S1. Pre-processing: Remove the aluminum frame, junction box and cables of the retired crystalline silicon photovoltaic module to obtain the main laminate. The retired crystalline silicon photovoltaic module is a monocrystalline silicon module. Before executing S1, pre-classification is also included, which categorizes components into low-damage, medium-to-high-damage, and severely damaged components. The corresponding processing route is determined based on the pre-classification results. (1) Criteria for judging low-damage components: A module is classified as a low-damage module if it meets all of the following conditions: the broken glass area accounts for less than 5% of the total area of ​​the module, and the broken area is located outside the area directly above the solar cells; the backsheet is free of powdering, cracking, and delamination; the module power degradation rate is less than 20%; and the module surface is free of severe dust accumulation, oil stains, and acid corrosion marks. For low-damage components, the processing route is: execute S1~S6; (2) Criteria for determining medium to high damage components: A module is classified as a medium-to-high damage module if it meets any of the following conditions: the broken glass area accounts for 5% to 30% of the total area of ​​the module; or the broken glass is located directly above the solar cell and has caused the solar cell to be exposed; or the broken glass has caused obvious water ingress inside the module. For medium to high damage components, the processing route is as follows: after executing S1, first scrape off the broken glass layer and wipe the exposed cell layer clean, and then execute S2~S5. (3) Criteria for determining severely damaged components: A module is deemed severely damaged if it meets any of the following conditions: the broken glass area accounts for more than 30% of the total area of ​​the module; or more than 20% of the cells are obviously broken or missing; or the backsheet has a large area of ​​pulverization, cracking, delamination or detachment, and the pulverized area exceeds 50% of the total area of ​​the backsheet; or the backsheet is a fluorine-containing backsheet and has obviously yellowed or become embrittled; or the module has been in service for more than 20 years and the power degradation rate exceeds 30%; or the module surface has obvious acid corrosion, hot spot burning or fire marks. For severely damaged components, the processing route is as follows: after executing S1, the main laminate is directly fed into the crushing equipment for mechanical crushing. After crushing, the metal components, glass materials and silicon materials are screened out and then enter the silver, copper and silicon graded recycling in S6. In this embodiment, the decommissioned crystalline silicon photovoltaic module is a low-damage module; S2. Opening treatment: The edge of the main laminate is opened by mechanical cutting to expose the EVA encapsulation layer interface. A circular saw is used to cut along the edge of the main laminate at 3mm. S3. Directional Activation: The interface activation medium is penetrated along the interface between the EVA encapsulation layer and each material layer by spraying, circulating rinsing, or immersion to reduce the interfacial adhesion strength between the EVA encapsulation layer and each material layer. Directional activation is performed by spraying, with an activation temperature of 50℃, an activation time of 80 min, and an interface activation medium flow rate of 20 L / min·m. 2 The spray pressure is 0.2 MPa; The interface activation medium is n-butanol, an alcohol-based medium, with a pH of 7 and a mass concentration of 75%. S4. Heat-assisted softening: The EVA encapsulation layer after directional activation is subjected to low-temperature heat-assisted softening at 150°C for 15 minutes. The method of low-temperature heat-assisted softening is hot air. S5. Flexible peeling: The EVA encapsulation layer after heat-assisted softening is flexibly peeled to separate the glass layer, EVA residual film, backsheet layer, battery cell layer and metal components. The flexible peeling method is hot knife peeling with a knife temperature of 280℃. S6. Graded recycling: Graded recycling of silver, copper and silicon from battery cell layers and metal components; The silver grading and recycling method involves firstly, subjecting the battery cell layers obtained through flexible peeling to low-temperature heat treatment at 400℃ for 80 minutes to remove residual EVA and organic matter from the backsheet; then, thoroughly washing with an alkaline solution (sodium hydroxide or potassium hydroxide solution, 5 wt% concentration, at 60℃) to remove the aluminum backsheet surface of the battery cells; subsequently, thoroughly acid washing the alkaline-washed battery cell layers with an acidic solution (dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid, pH 2) to remove the oxide layer and impurities from the silver electrode surface; and then... After acid washing, the battery wafer layers were selectively leached with nitric acid solution to allow silver to enter the leaching solution in ionic form, achieving solid-liquid separation between silver and silicon wafers. The molar concentration of the nitric acid solution was 4 mol / L, and the liquid-to-solid ratio was 4.5 mL:1 g. The mixture was stirred at 66 °C for 50 min. The resulting silver-containing leaching solution was then subjected to reduction precipitation using ascorbic acid as the reducing agent. The molar ratio of ascorbic acid to silver ions was 1.5:1. The reaction was carried out under conditions of pH 4 and 40 °C for 40 min. After solid-liquid separation, washing, and drying, metallic silver powder was obtained. The graded recovery method for copper involves mechanically separating the copper solder strip and cable from the metal components to obtain copper strip. The copper strip is then placed in a mixed solution of 6 mol / L acetic acid and 0.6 mL / L hydrogen peroxide, with a liquid-to-solid ratio of 6 mL:1 g, and reacted at 50°C for 50 min. This allows the lead-tin plating to selectively dissolve while the copper substrate remains insoluble. After solid-liquid separation, high-purity copper strip is obtained. The graded recycling method for silicon involves placing the remaining silicon-containing material in the silicon material or battery wafer layers and metal components into a hydrochloric acid solution for acid washing to remove residual metal impurities and metal oxides on the surface of the silicon material. The mass fraction of hydrochloric acid is 10%, and the liquid-to-solid ratio is 8 mL:1 g. The reaction is carried out at 40°C for 40 min. After acid washing, solid-liquid separation is performed. The obtained silicon material is then placed in a sodium hydroxide solution for alkaline etching to remove the silicon nitride antireflective layer and residual aluminum impurities on the surface of the silicon wafer. The molar concentration of sodium hydroxide is 2 mol / L. The reaction is carried out at 50°C for 20 min, and the liquid-to-solid ratio is 8 mL:1 g. After alkaline etching, solid-liquid separation is performed. The obtained silicon material is repeatedly washed with deionized water until neutral, and then dried to obtain recycled silicon material.

[0028] Example 2: This example differs from Example 1 in that, S1, pretreatment: the decommissioned crystalline silicon photovoltaic module is a polycrystalline silicon module; in this example, the decommissioned crystalline silicon photovoltaic module is a low-damage module. S2. Opening treatment: The edge opening of the main laminate is treated by laser scribing to expose the interface of the EVA encapsulation layer. The laser power is 30W and the cutting depth is 0.5mm. S3. Directional Activation: A circulating rinsing method is used, with an activation temperature of 40℃ and an activation time of 120 min. The flow rate of the interface activation medium is 10 L / min·m. 2 The spray pressure was 0.6 MPa, the interface activation medium was ethyl acetate (an ester-based medium), the pH of the interface activation medium was 7.5, and the mass concentration of the interface activation medium was 25%. S4. Thermal assisted softening: The EVA encapsulation layer after directional activation is subjected to low-temperature thermal assisted softening at 180℃ for 20 minutes. The low-temperature thermal assisted softening method is infrared, and the infrared wavelength is 1070nm. S5. Flexible peeling: The flexible peeling method is hot knife peeling, and the knife body temperature is 300℃.

[0029] Example 3: This example differs from Example 1 in that, S1, pretreatment: the decommissioned crystalline silicon photovoltaic module is a single-glass module; in this example, the decommissioned crystalline silicon photovoltaic module is a medium-to-high damage module. S2. Opening treatment: The edge opening of the main laminate is treated by laser scribing to expose the interface of the EVA encapsulation layer. The laser power is 100W and the cutting depth is 2mm. S3. Directional Activation: The EVA encapsulation layer is completely immersed in the interface activation medium at an activation temperature of 90℃ for 10 minutes. The volume ratio of the interface activation medium to the EVA encapsulation layer is 3:1. The interface activation medium is a surfactant compound solution of fatty alcohol polyoxyethylene ether, with a pH of 8 and a mass concentration of 0.1%. S4. Thermal assisted softening: The EVA encapsulation layer after directional activation is subjected to low-temperature thermal assisted softening at 120℃ for 30 minutes. The low-temperature thermal assisted softening method is microwave, and the microwave power is 150W. S5. Flexible peeling: The flexible peeling method is roller peeling, and the roller pressure is 0.2MPa.

[0030] Example 4: This example differs from Example 1 in that, S1, pretreatment: the decommissioned crystalline silicon photovoltaic module is a double-glass module; in this example, the decommissioned crystalline silicon photovoltaic module is a medium-to-high damage module. S2. Opening treatment: The edge of the main laminate is opened by local grinding to expose the interface of the EVA encapsulation layer. The grinding wheel is used to grind along the edge of the main laminate to a depth of 0.5mm and a speed of 3000rpm. S3. Directional Activation: The EVA encapsulation layer is completely immersed in the interface activation medium at an activation temperature of 690℃ for 60 min. The volume ratio of the interface activation medium to the EVA encapsulation layer is 10:1. The interface activation medium is a surfactant compound alkyl glycoside with a pH of 7 and a mass concentration of 0.2%. S4. Thermal Assisted Softening: The EVA encapsulation layer after directional activation is subjected to low-temperature thermal assisted softening at 220℃ for 10 minutes. The low-temperature thermal assisted softening method is microwave, and the microwave power is 400W. S5. Flexible peeling: The flexible peeling method is roller peeling, and the roller pressure is 0.5MPa.

[0031] Example 5: This example differs from Example 1 in that, S1, pretreatment: the decommissioned crystalline silicon photovoltaic module is a crystalline silicon module with a backsheet; in this example, the decommissioned crystalline silicon photovoltaic module is a medium-to-high damage module. S2. Opening treatment: The edge of the main laminate is opened by local grinding to expose the interface of the EVA encapsulation layer. The grinding wheel is used to grind along the edge of the main laminate to a depth of 2mm and a speed of 5000rpm. S3. Directional Activation: The activation method is immersion at 55℃ for 90 min. The EVA encapsulation layer is completely immersed in the interface activation medium, with a volume ratio of 5:1 between the interface activation medium and the EVA encapsulation layer. The interface activation medium is a surfactant compound solution of fatty alcohol polyoxyethylene ether, with a pH of 7 and a mass concentration of 0.1%. S5. Flexible peeling: The flexible peeling method is vacuum adsorption peeling, and the vacuum degree is maintained at -60kPa.

[0032] Example 6: This example differs from Example 1 in that, S1, pretreatment: the decommissioned crystalline silicon photovoltaic module is a fluorine-containing backsheet crystalline silicon module; in this example, the decommissioned crystalline silicon photovoltaic module is a low-damage module; S2. Opening treatment: The edge of the main laminate is opened by using a hot knife to expose the interface of the EVA encapsulation layer. The hot knife is heated to 200℃ and the cutting depth is 1mm. S3. Directional Activation: A circulating rinsing method is used, with an activation temperature of 80℃ and an activation time of 20 min. The flow rate of the interface activation medium is 5 L / min·m³. 2The spray pressure was 0.8 MPa; the interface activation medium was an aqueous solution of sodium hydroxide, with a pH of 11 and a mass concentration of 5%. S5. Flexible peeling: The flexible peeling method is ultrasonic-assisted peeling, with an ultrasonic power of 800W and an ultrasonic frequency of 40kHz.

[0033] Example 7: The difference between this example and Example 1 is that, S2, opening treatment: the main laminate is opened at the edge by mechanical cutting to expose the EVA encapsulation layer interface, and a circular saw is used to cut along the edge of the main laminate at 2mm.

[0034] Example 8: The difference between this example and Example 1 is that, S2, opening treatment: the main laminate is opened at the edge by mechanical cutting to expose the EVA encapsulation layer interface, and a circular saw is used to cut along the edge of the main laminate at 5mm.

[0035] Example 9: The difference between this example and Example 6 is that, S2, opening treatment: the edge opening treatment of the main laminate is performed by hot knife cutting to expose the interface of the EVA encapsulation layer. The hot knife heating temperature is 300℃ and the cutting depth is 3mm.

[0036] Example 10: The difference between this example and Example 1 is that the interface activation medium in S3 is anhydrous ethanol.

[0037] Example 11: The difference between this example and Example 1 is that the interface activation medium in S3 is isopropanol.

[0038] Example 12: The difference between this example and Example 6 is that the interface activation medium in S3 is a water-based green swelling system, which is prepared by menthol-decanoic acid in a 1:1 mass ratio.

[0039] Example 13: The difference between this example and Example 6 is that the interface activation medium in S3 is an aqueous solution of sodium carbonate.

[0040] Example 14: The difference between this example and Example 5 is that, S5, flexible peeling: the flexible peeling method is vacuum adsorption peeling, and the vacuum degree is maintained at -90kPa.

[0041] Example 15: The difference between this example and Example 5 is that, S5, flexible peeling: the flexible peeling method is ultrasonic-assisted peeling, the ultrasonic power is 720W, and the ultrasonic frequency is 28kHz.

[0042] Example 16: The difference between this example and Example 1 is that the retired crystalline silicon photovoltaic module in this example is a severely damaged module. The processing route is as follows: after executing S1, the main laminate is directly sent to the crushing equipment for mechanical crushing. After crushing, the metal components, glass material and silicon material are screened out and then enter the graded recycling of silver, copper and silicon in S6. The graded recycling method for silver involves firstly, subjecting the battery cell layers obtained through flexible peeling to low-temperature heat treatment at 300℃ for 30 minutes to remove residual EVA and organic matter from the backsheet; then, thoroughly washing with an alkaline solution (sodium hydroxide or potassium hydroxide solution, 1 wt% concentration, at 50℃) to remove the aluminum backsheet surface of the battery cells; subsequently, thoroughly acid washing the alkaline-washed battery cell layers with an acidic solution (dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid, pH 1) to remove the oxide layer and impurities from the silver electrode surface; The acid-washed battery wafer layers were then selectively leached with silver using a nitric acid solution, allowing silver to enter the leaching solution in ionic form, thus achieving solid-liquid separation between silver and silicon wafers. The molar concentration of the nitric acid solution was 3 mol / L, and the liquid-to-solid ratio was 4 mL:1 g. The mixture was stirred at 65 °C for 45 min. The resulting silver-containing leaching solution was then subjected to reduction precipitation using ascorbic acid as the reducing agent. The molar ratio of ascorbic acid to silver ions was 1:1. The mixture was stirred at pH 3.5 and 30 °C for 30 min. After solid-liquid separation, washing, and drying, metallic silver powder was obtained. The graded recovery method of copper involves mechanically separating the copper solder strip and cable from the metal component to obtain copper strip. The copper strip is then placed in a mixed solution of 5 mol / L acetic acid and 0.5 mL / L hydrogen peroxide with a liquid-to-solid ratio of 5 mL:1 g and reacted at 40°C for 30 min. This allows the lead-tin plating to selectively dissolve while the copper substrate remains insoluble. After solid-liquid separation, high-purity copper strip is obtained. The graded recycling method for silicon involves placing the remaining silicon-containing material in the silicon material or battery wafer layers and metal components into a hydrochloric acid solution for acid washing to remove residual metal impurities and metal oxides on the surface of the silicon material. The mass fraction of hydrochloric acid is 5%, and the liquid-to-solid ratio is 5 mL:1 g. The reaction is carried out at 30°C for 20 min. After acid washing, solid-liquid separation is performed. The obtained silicon material is then placed in a sodium hydroxide solution for alkaline etching to remove the silicon nitride antireflective layer and residual aluminum impurities on the surface of the silicon wafer. The molar concentration of sodium hydroxide is 1 mol / L. The reaction is carried out at 40°C for 10 min, and the liquid-to-solid ratio is 5 mL:1 g. After alkaline etching, solid-liquid separation is performed. The obtained silicon material is repeatedly washed with deionized water until neutral, and then dried to obtain recycled silicon material.

[0043] Example 17: The difference between this example and Example 1 is that the retired crystalline silicon photovoltaic module in this example is a severely damaged module. The processing route is as follows: after S1, the main laminate is directly sent to the crushing equipment for mechanical crushing. After crushing, the metal components, glass material and silicon material are screened out and then enter the graded recycling of silver, copper and silicon in S6. The graded recycling method for silver involves firstly, subjecting the battery cell layers obtained by flexible peeling to low-temperature heat treatment at 500℃ for 120 minutes to remove residual EVA and organic matter from the backsheet; then, thoroughly washing with an alkaline solution (sodium hydroxide or potassium hydroxide solution, 10wt% concentration, at 80℃) to remove the aluminum backsheet surface of the battery cells; subsequently, thoroughly washing the alkaline-washed battery cell layers with an acidic solution (dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid, pH 3) to remove the oxide layer and impurities from the surface of the silver electrode; The acid-washed battery wafer layers were then selectively leached with silver using a nitric acid solution, allowing silver to enter the leaching solution in ionic form, thus achieving solid-liquid separation between silver and the silicon wafer. The molar concentration of the nitric acid solution was 5 mol / L, and the liquid-to-solid ratio was 5 mL:1 g. The mixture was stirred at 70 °C for 60 min. The resulting silver-containing leaching solution was then subjected to reduction precipitation using ascorbic acid as the reducing agent. The molar ratio of ascorbic acid to silver ions was 2:1. The reaction was carried out under conditions of pH 4.5 and a temperature of 50 °C for 60 min. After solid-liquid separation, washing, and drying, metallic silver powder was obtained. The graded recovery method for copper involves mechanically separating the copper solder strip and cable from the metal components to obtain copper strip. The copper strip is then placed in a mixed solution of 7 mol / L acetic acid and 0.75 mL / L hydrogen peroxide, with a liquid-to-solid ratio of 10 mL:1 g. The reaction is carried out at 60 °C for 60 min, allowing the lead-tin plating to selectively dissolve while the copper substrate remains insoluble. After solid-liquid separation, high-purity copper strip is obtained. The graded recycling method for silicon involves placing the remaining silicon-containing material in the silicon material or battery wafer layers and metal components into a hydrochloric acid solution for acid washing to remove residual metal impurities and metal oxides on the surface of the silicon material. The mass fraction of hydrochloric acid is 15%, the liquid-to-solid ratio is 10 mL: 1 g, and the reaction is carried out at 50 °C for 60 min. After acid washing, solid-liquid separation is performed. The obtained silicon material is then placed in a sodium hydroxide solution for alkaline etching to remove the silicon nitride antireflective layer and residual aluminum impurities on the surface of the silicon wafer. The molar concentration of sodium hydroxide is 2.5 mol / L, and the reaction is carried out at 60 °C for 30 min with a liquid-to-solid ratio of 10 mL: 1 g. After alkaline etching, solid-liquid separation is performed. The obtained silicon material is repeatedly washed with deionized water until neutral, and then dried to obtain recycled silicon material.

[0044] Experimental Example: The corresponding decommissioned crystalline silicon photovoltaic modules were recycled according to the methods of Example 1, Example 3 and Example 6 respectively, and compared with several comparative examples to test the recovery rates of glass, silver, copper and silicon. The operating conditions and advantages and disadvantages of the comparative examples are shown in Table 1.

[0045] Table 1. Comparison of Operating Conditions and Advantages / Disadvantages in the Comparative Study

[0046] The specific recovery rates are shown in the figure. It can be seen that the glass integrity recovery rate of this invention is 85%~92%, significantly better than Comparative Example 1 (65%), Comparative Example 2 (80%), and Comparative Example 3 (82%); the silver recovery rate is 85%~88%, better than all comparative examples (70%~78%); the copper recovery rate is 90%~92%, better than all comparative examples (80%~83%); and the silicon recovery rate is 75%~78%, better than all comparative examples (50%~62%). Furthermore, it saves 40%~45% on energy consumption per unit. Comparative Example 4 uses a pure wet leaching route without front-end stripping, therefore its glass and silicon recovery rates are not applicable.

[0047] Among them, the low-breakage monocrystalline silicon module in Example 1 has better performance in all aspects than the medium-high breakage monocrystalline glass module in Example 3. The fluorine-containing backsheet in Example 6 has slightly lower performance in all aspects than Example 1 due to the limited softening temperature, but it is still within the range of high recovery rate. All aspects of the present invention are better than all comparative examples, which can improve the glass integrity recovery rate, silicon wafer recovery rate and silver and copper recovery efficiency.

Claims

1. A method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules, characterized in that, Includes the following steps: S1. Pre-processing: Remove the aluminum frame, junction box and cables of the retired crystalline silicon photovoltaic module to obtain the main laminate; S2. Opening treatment: The main laminate is opened at the edges by physical cutting to expose the EVA encapsulation layer interface. S3. Targeted activation: The interface activation medium is permeated along the interface between the EVA encapsulation layer and each material layer by means of spraying, circulating rinsing or immersion. S4. Heat-assisted softening: The EVA encapsulation layer after directional activation is subjected to low-temperature heat-assisted softening at 120~220℃ for 10~30min. S5. Flexible peeling: The EVA encapsulation layer after heat-assisted softening is flexibly peeled off to separate the glass layer, EVA residual film, backsheet layer, battery cell layer and metal components. S6. Graded recycling: The battery cell layers and metal components are graded and recycled for silver, copper and silicon.

2. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 1, characterized in that, In S1, the retired crystalline silicon photovoltaic module is a monocrystalline silicon module, a polycrystalline silicon module, a single-glass module, a double-glass module, a crystalline silicon module with a backsheet, or a crystalline silicon module with a fluorine-containing backsheet.

3. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 1, characterized in that, Before executing S1, pre-classification is also included, which categorizes components into low-damage, medium-to-high-damage, and severely damaged components. The corresponding processing route is determined based on the pre-classification results. (1) Criteria for judging low-damage components: A module is classified as a low-damage module if it meets all of the following conditions: the broken glass area accounts for less than 5% of the total area of ​​the module, and the broken area is located outside the area directly above the solar cells; the backsheet is free of powdering, cracking, and delamination; the module power degradation rate is less than 20%; and the module surface is free of severe dust accumulation, oil stains, and acid corrosion marks. For low-damage components, the processing route is: execute S1~S6; (2) Criteria for determining medium to high damage components: A module is classified as a medium-to-high damage module if it meets any of the following conditions: the broken glass area accounts for 5% to 30% of the total area of ​​the module; or the broken glass is located directly above the solar cell and has caused the solar cell to be exposed; or the broken glass has caused obvious water ingress inside the module. For medium to high damage components, the processing route is as follows: after executing S1, first scrape off the broken glass layer and wipe the exposed cell layer clean, and then execute S2~S5. (3) Criteria for determining severely damaged components: A module is deemed severely damaged if it meets any of the following conditions: the broken glass area accounts for more than 30% of the total area of ​​the module; or more than 20% of the cells are obviously broken or missing; or the backsheet has a large area of ​​pulverization, cracking, delamination or detachment, and the pulverized area exceeds 50% of the total area of ​​the backsheet; or the backsheet is a fluorine-containing backsheet and has obviously yellowed or become embrittled; or the module has been in service for more than 20 years and the power degradation rate exceeds 30%; or the module surface has obvious acid corrosion, hot spot burning or fire marks. For severely damaged components, the processing route is as follows: after executing S1, the main laminate is directly fed into the crushing equipment for mechanical crushing. After crushing, the metal components, glass materials and silicon materials are screened out and then enter the graded recycling of silver, copper and silicon in S6.

4. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 3, characterized in that, In S2, the physical cutting includes mechanical cutting, hot knife edge cutting, laser scribing, or localized grinding. Mechanical cutting is suitable for the low-breakage components, using a circular saw to cut along the edge of the main laminate at a distance of 2-5 mm. Hot knife edge cutting is suitable for the fluorine-containing main laminate, with a hot knife heating temperature of 200-300℃ and a cutting depth of 1-3 mm. Laser scribing is suitable for the low-breakage components or medium-to-high-breakage components, with a laser power of 30-100W and a cutting depth of 0.5-2 mm. Localized grinding is suitable for the medium-to-high-breakage components, using a grinding wheel to grind along the edge of the main laminate, with a grinding depth of 0.5-2 mm and a grinding wheel speed of 3000-5000 rpm.

5. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 3, characterized in that, In S3, the activation temperature is 40~90℃, and the activation time is 10~120 min. For the low-damage components, a spraying or circulating rinsing method is used, with an interface activation medium flow rate of 5~20 L / min·m. 2 The spray pressure is 0.2~0.8MPa; for the medium and high damage components, the EVA encapsulation layer is completely immersed in the interface activation medium by immersion, and the volume ratio of the interface activation medium to the EVA encapsulation layer is 3~10:

1.

6. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 3, characterized in that, In S3, the interface activation medium is an alcohol-based medium, an ester-based medium, a weakly alkaline aqueous solution, a surfactant compound solution, or a water-based green swelling system. The pH of the interface activation medium is 7-11, and the mass concentration of the interface activation medium is 0.1-75%. For the low-damage components, alcohol-based or ester-based media are selected; for medium- to high-damage components, surfactant-based compound solutions are selected; for the fluorine-containing main laminate, weakly alkaline aqueous solutions or water-based green swelling systems are selected. The alcohol medium is anhydrous ethanol, n-butanol, or isopropanol; the ester medium is ethyl acetate; the weakly alkaline aqueous solution is sodium hydroxide aqueous solution or sodium carbonate aqueous solution; the surfactant compound solution is fatty alcohol polyoxyethylene ether or alkyl glycoside; and the water-based green swelling system is prepared by menthol-decanoic acid in a 1:1 mass ratio.

7. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 1, characterized in that, In S4, the low-temperature heat-assisted softening method includes hot air, infrared or microwave, wherein the infrared wavelength is 1070nm and the microwave power is 150~400W.

8. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 1, characterized in that, In S5, the flexible peeling methods include hot knife peeling, roller peeling, vacuum adsorption peeling, or ultrasonic-assisted peeling. Among them, the blade temperature of hot knife peeling is 280~300℃, the roller pressure of roller peeling is 0.2~0.5MPa, the vacuum degree of vacuum adsorption peeling is maintained at -60~-90kPa, and the ultrasonic power of ultrasonic-assisted peeling is 720~800W, and the ultrasonic frequency is 28~40kHz.

9. The method for low-temperature interface dissociation and graded recycling of high-value materials in decommissioned crystalline silicon photovoltaic modules according to claim 3, characterized in that, In S6, the graded recovery method for silver involves firstly, subjecting the battery cell layers obtained from flexible peeling to low-temperature heat treatment at 300-500℃ for 30-120 minutes, followed by thorough alkaline washing with an alkaline solution (sodium hydroxide or potassium hydroxide solution, concentration 1-10 wt%, treatment temperature 50-80℃). Subsequently, the alkaline-washed battery cell layers are thoroughly acid-washed with an acidic solution (dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid, pH 1-3). Finally, the acid-washed battery cell layers are selectively treated with a nitric acid solution for silver recovery. Leaching is performed to allow silver to enter the leachate in ionic form, achieving solid-liquid separation between silver and silicon wafers. The molar concentration of the nitric acid solution is 3-5 mol / L, and the liquid-to-solid ratio is 4-5 mL:1 g. The mixture is stirred at 65-70°C for 45-60 min. The resulting silver-containing leachate is then subjected to reduction precipitation using ascorbic acid as the reducing agent. The molar ratio of ascorbic acid to silver ions is 1-2:

1. The mixture is stirred at pH 3.5-4.5 and temperature 30-50°C for 30-60 min. After solid-liquid separation, washing, and drying, metallic silver powder is obtained. The method for graded recovery of copper is to mechanically separate the copper solder strip and cable in the metal component to obtain copper strip, place the copper strip in a mixed solution of 5~7mol / L acetic acid and 0.5~0.75mL / L hydrogen peroxide with a liquid-to-solid ratio of 5~10mL:1g, react at 40~60℃ for 30~60min, and obtain high-purity copper strip after solid-liquid separation; The graded recycling method for silicon involves placing the silicon material or the remaining silicon-containing material in the battery cell layer and the metal component into a hydrochloric acid solution for acid washing. The mass fraction of the hydrochloric acid is 5-15%, and the liquid-to-solid ratio is 5-10 mL:1 g. The reaction is carried out at 30-50°C for 20-60 min. After acid washing, solid-liquid separation is performed. The obtained silicon material is then placed into a sodium hydroxide solution for alkaline etching treatment. The molar concentration of sodium hydroxide is 1-2.5 mol / L. The reaction is carried out at 40-60°C for 10-30 min, and the liquid-to-solid ratio is 5-10 mL:1 g. After alkaline etching, solid-liquid separation is performed. The obtained silicon material is repeatedly washed with deionized water until neutral, and then dried to obtain recycled silicon material.

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