Process for efficiently separating out-of-service photovoltaic module based on low-temperature green medicament method

Abstract

The invention relates to the technical field of retired photovoltaic module recovery treatment, and particularly discloses a process for efficiently separating a retired photovoltaic module based on a low-temperature green medicament method, which mainly comprises the following steps: (1) pre-treating the retired photovoltaic module, (2) infiltrating and swelling the pre-treated retired photovoltaic module by using a green mixed medicament, and carrying out solid-liquid separation to obtain a solid-state battery piece; (3) cleaning residual ethylene-vinyl acetate by using an alkaline alcohol solution, carrying out solid-liquid separation to obtain a solid-state battery piece, and then cleaning by using absolute ethyl alcohol and deionized water; and (4) recovering the medicament from the separation liquid after the solid-liquid separation in the two steps. According to the treatment process provided by the invention, the link of removing EVA in the photovoltaic module recovery process is efficient and simple, the purity of the cleaned battery piece is as high as 99.95%, the recovery value is high, the medicament can be recycled, and the treatment process has a very good industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and processing of retired photovoltaic modules, and in particular to a process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method. Background Art

[0002] With the improvement of science and technology and the continuous advancement of photovoltaic power generation, the progress of photovoltaic module technology has accelerated. my country's photovoltaic module recycling field has developed rapidly. By 2023, the number of failed photovoltaic modules in the Chinese market will reach 7-10GW, and the module recycling value will be about 5 billion yuan. It is estimated that by 2030, there will be 9-20GW of modules to be recycled in the Chinese market, and by 2050, there will be about 170-270GW of modules to be recycled, with a recoverable value of about 110 billion yuan. In the global market, it is estimated that by 2025, there will be 15-27GW of modules to be recycled, by 2030, there will be 23-110GW of modules to be recycled, and by 2050, there will be about 800-1000GW of modules to be recycled, and the cumulative recoverable value of the modules will exceed 400 billion yuan. The future market prospects are huge.

[0003] The current processing methods for component recycling and their advantages and disadvantages are as follows:

[0004] 1. Thermal Treatment

[0005] The thermal treatment method is to heat the photovoltaic module to a temperature sufficient to decompose or vaporize the EVA film. The usual treatment temperature is between 300 and 600°C. During the pyrolysis process, EVA decomposes into small molecules, such as acetic acid, ethylene, and other volatile organic compounds. These decomposition products evaporate at high temperatures, thereby separating EVA from glass and silicon wafers.

[0006] Advantages: This method can quickly separate materials such as silicon wafers, glass and metal. At the right temperature, EVA can be almost completely removed, with a removal rate of more than 90%. The heat treatment technology is relatively mature and has been applied in some photovoltaic module recycling plants.

[0007] Disadvantages: High temperature treatment requires a lot of energy, which increases the cost of recycling. High temperature may cause EVA on the surface of silicon wafers and glass to be heated unevenly and carbonized and coated on the surface of silicon wafers and glass, affecting subsequent recycling. Thermal decomposition of EVA will produce harmful gases (such as acetic acid, ethylene, acetaldehyde, propylene, carbon monoxide, and various volatile organic compounds), and waste gas treatment equipment is required to reduce environmental pollution.

[0008] 2. Chemical Treatment

[0009] The chemical treatment method uses chemical agents (such as organic solvents, alkali solutions, acid solutions, etc.) to swell, dissolve or decompose the EVA film, thereby achieving layer separation. Commonly used agents include organic solvents such as ethanol, acetone, toluene, xylene, or inorganic chemicals such as sodium hydroxide and sulfuric acid. After the chemical agents react with EVA, the viscosity of EVA is greatly reduced and it can be separated from the silicon wafer and glass.

[0010] Advantages: Most chemical treatments can be performed at room temperature or slightly higher temperatures to avoid thermal damage. By selecting the right agent, the removal rate of EVA can reach 80-90%. A variety of different types of photovoltaic modules can be treated.

[0011] Disadvantages: Some chemicals may be corrosive or toxic to equipment and operators, requiring strict protective measures. The reaction speed is relatively slow and the treatment efficiency is low. The used chemicals may contain harmful substances and need to go through complex waste liquid treatment steps to avoid environmental pollution.

[0012] 3. Mechanical Treatment

[0013] Mechanical treatment uses physical means such as cutting, peeling, grinding, etc. to separate the layers of photovoltaic modules. Specific equipment includes cutting machines, peeling machines, grinders, etc. EVA film is usually removed from the silicon wafer or glass surface by mechanical destruction or grinding.

[0014] Advantages: Avoids the use of chemical agents, environmentally friendly and safe. Compared with thermal treatment and some chemical treatments, mechanical methods consume less energy. Mechanical equipment is widely available and easy to integrate into production lines.

[0015] Disadvantages: Mechanical methods have limited removal rates for EVA, usually between 50% and 70%, and are prone to residue. Mechanical forces may damage silicon wafers and glass, causing EVA to become entangled with glass and silicon wafer particles and difficult to effectively separate, reducing the quality of recycled materials. Mechanical processing may generate a lot of dust and noise, requiring additional processing equipment. Summary of the invention

[0016] The purpose of the present invention is to fully understand the deficiencies of various methods in the prior art, and in combination with economic benefits, to provide a process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method. Through the precise proportion of different agents, the adhesive EVA in the module is removed at a low cost under appropriate stirring and heating conditions to obtain a surface-cleaned battery cell with high recovery value, which can realize the industrialization and large-scale recycling of valuable components of retired modules. Compared with the traditional chemical method, in addition to being green and environmentally friendly, the present invention creatively proposes a two-step method to process the EVA layer on both sides of the battery cell, which improves efficiency and also improves product purity.

[0017] In order to achieve the above object, the present invention provides the following technical solutions:

[0018] A green mixed agent for efficiently separating retired photovoltaic modules at low temperature, wherein the green mixed agent is precisely prepared by mixing N,N-dimethylpropylene urea and D-limonene in a volume ratio of 0.1:10 to 10:0.1.

[0019] As a limitation of the present invention, the preparation method of the green mixed agent is:

[0020] Calculated by volume fraction, N,N-dimethylpropylene urea is added to D-limonene which accounts for 20-40% of the total volume of the green mixed agent. The amount added each time is 5-15% of the total volume of the green mixed agent. The interval between each addition is 15-25 minutes. After the addition of N,N-dimethylpropylene urea is completed, the reaction is continued for 1-7 hours to obtain a green mixed agent.

[0021] A process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method, specifically:

[0022] Step 1: pre-processing retired photovoltaic modules to obtain pre-processed retired photovoltaic modules;

[0023] Step 2: Heat the green mixed reagent to 60-300°C, add it into the pre-treated retired photovoltaic modules, fully infiltrate and swell them, and separate the solid-liquid into solid-state cells;

[0024] Step 3: Heat the alkaline alcohol solution to 30-200°C, add the solid battery cell, and after thorough cleaning, separate the solid and liquid to obtain a clean battery cell;

[0025] Step 4: Recover the reagent from the separated liquid after solid-liquid separation in the above two steps.

[0026] As a limitation of the present invention, the pretreatment of retired photovoltaic modules is specifically as follows: first mechanically dismantle the frame of the retired photovoltaic modules, then mechanically grind off the glass on the surface of the photovoltaic modules, and cut them into (1cm×1cm) to (10cm×10cm) fragments to obtain pretreated retired photovoltaic modules.

[0027] As a limitation of the present invention, during the infiltration and swelling, the volume ratio of the added pre-treated retired photovoltaic module to the green mixed agent is (5m 2 :1m 3 )~(100m 2 :1m 3 ).

[0028] As a limitation of the present invention, stirring is required during the infiltration and swelling of the pre-treated retired photovoltaic modules, the stirring speed is set to 10 to 1000 rpm, and the infiltration and swelling time is 1 to 10 hours.

[0029] As a limitation of the present invention, the alkaline alcohol solution consists of sodium hydroxide and n-hexanol, and the concentration of sodium hydroxide is 1 g to 5 g / L.

[0030] As a limitation of the present invention, the ratio of the mass of sodium hydroxide in the alkaline alcohol solution to the area of ​​the pretreated retired photovoltaic modules is 10 g / m 2 ~1000g / m 2 .

[0031] As a limitation of the present invention, in step 3, when washing with an alkaline alcohol solution, the temperature needs to be raised to 30-200° C., the stirring speed is set to 50-1000 rpm, and the washing time is 10-300 min.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention exposes the EVA near one side of the glass by disassembling the recycled photovoltaic module and crushing the surface glass, thereby increasing the liquid-solid contact area and the solvent penetration rate. At the same time, the module is cut into small pieces to reduce the penetration distance perpendicular to the cross-sectional direction, which is convenient for the subsequent solvent swelling process. At a certain temperature, appropriate stirring is added, and the EVA on both sides of the battery sheet expands in volume and decreases in viscosity. Under the participation of shear force, the battery sheet and the EVA layer are separated from each other. However, part of the EVA still remains on the battery sheet, and it is necessary to carry out a thorough cleaning. After the unwashed battery sheet is separated from the solid and liquid, it is put into an alkaline alcohol solution composed of sodium hydroxide and n-hexanol, and the ester bond characteristics in the ethylene-vinyl acetate copolymer are used to cause saponification and hydrolysis reaction under alkaline conditions, and the EVA is converted into EVOH, and potassium acetate is produced at the same time, and the viscosity is lost, thereby cleaning the EVA on the surface of the battery sheet. Then, the clean battery sheet can be obtained by washing with anhydrous ethanol and deionized water in succession, which is convenient for the subsequent recovery of silver. Compared with the traditional chemical method, in addition to being green and environmentally friendly, the present invention creatively proposes a two-step method to process the EVA layers on both sides of the battery cell, which improves efficiency while also improving product purity.

[0034] The treatment process provided by the present invention does not require the use of equipment that is complicated to operate or expensive, and is combined with a chemical method through simple mechanical pretreatment. Compared with the traditional chemical method, the present invention does not use toxic and harmful agents, is green and environmentally friendly, and through appropriate agent selection and precise proportioning, the entire process can process a large number of components in a short time, and the organic solvent is recovered by reduced pressure drying, which reduces the cost of agents and solves the problem of waste liquid generated by traditional chemical methods. While meeting the requirements of environmental protection and energy consumption, it also has the advantages of industrialization and large-scale promotion, and realizes high-purity recovery of valuable components in retired photovoltaic components such as silver electrodes, aluminum frames, glass, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A schematic diagram of a process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method proposed by the present invention;

[0036] Figure 2 This is a comparison of the status of retired photovoltaic modules before and after the process treatment of Example 1. The left side shows the status of retired photovoltaic modules before treatment, and the right side shows the status of retired photovoltaic modules after treatment. DETAILED DESCRIPTION

[0037] The following will be combined Figure 1 The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the present invention, the mass fraction of silver in the retired photovoltaic modules is 0.05%, the mass fraction of EVA is 4%, the mass fraction of aluminum is 16%, and the mass fraction of glass is 64%, which are provided by Yangzhou Shanhong Environmental Protection Technology Co., Ltd. Reagents such as N,N-dimethylpropylene urea and D-limonene are all industrial products and can be purchased on the market.

[0039] Embodiment 1: A process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method, specifically:

[0040] Step 1: PV panel pretreatment

[0041] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 1cm×1cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0042] Step 2: Green mixed solvent degumming

[0043] Heat the green mixed solvent oil bath in the container to 60°C, add 500 pre-treated retired photovoltaic modules into 3L of D-limonene, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the stirring dead angle. Set the stirring speed to 100r / min, and then add 1L of N,N-dimethylpropylene urea every 20min for 7 times. Set the swelling time to 3h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated product is sieved with a sieve with a mesh size of 5 to obtain solid-state battery cells and a primary separation liquid.

[0044] Step 3: Degumming and cleaning with alkaline alcohol solution

[0045] Add 40 g of sodium hydroxide to 10 L of n-hexanol in another container, stir evenly to obtain an alkaline alcohol solution, heat to 30°C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 100 r / min, the reaction time is 10 min, remove the residual EVA on the surface of the battery cell, debond after alkaline hydrolysis and saponification, clean the surface of the battery cell, separate the battery cell into solid and liquid through a cyclone separator, and obtain the alkaline alcohol solution degummed battery cell and secondary separation liquid. First, use anhydrous ethanol to clean the organic components on the surface of the alkaline alcohol solution degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the alkaline alcohol solution degummed battery cell to obtain a clean battery cell.

[0046] Step 4: Recover the potion

[0047] The primary separation liquid and the secondary separation liquid are respectively sent to the vacuum dryer to recover the organic solvent and the reagent is recycled.

[0048] Embodiment 2: A process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method, specifically:

[0049] Step 1: PV panel pretreatment

[0050] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 5cm×5cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0051] Step 2: Green mixed solvent degumming

[0052] Heat the green mixed solvent oil bath in the container to 200°C, add 500 pre-treated retired photovoltaic modules into 3L of D-limonene, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the stirring dead angle. Set the stirring speed to 200r / min, and then add 1L of N,N-dimethylpropylene urea every 20min for 7 times. Set the swelling time to 4h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated product is sieved with a mesh of 5 to obtain solid-state battery cells and a primary separation liquid.

[0053] Step 3: Degumming and cleaning with alkaline alcohol solution

[0054] Add 40 g of sodium hydroxide to 10 L of n-hexanol in another container, stir evenly to obtain an alkaline alcohol solution, heat to 90°C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 200 r / min, the reaction time is 100 min, remove the residual EVA on the surface of the battery cell, debond after alkaline hydrolysis and saponification, clean the surface of the battery cell, separate the battery cell into solid and liquid through a cyclone separator, and obtain the alkaline alcohol solution degummed battery cell and secondary separation liquid. First, use anhydrous ethanol to clean the organic components on the surface of the alkaline alcohol solution degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the alkaline alcohol solution degummed battery cell to obtain a clean battery cell.

[0055] Step 4: Recover the potion

[0056] The primary separation liquid and the secondary separation liquid are respectively sent to the vacuum dryer to recover the organic solvent and the reagent is recycled.

[0057] Embodiment 3: A process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method, specifically:

[0058] Step 1: PV panel pretreatment

[0059] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 10cm×10cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0060] Step 2: Green mixed solvent degumming

[0061] Heat the green mixed solvent oil bath in the container to 300°C, add 500 pre-treated retired photovoltaic modules into 3L of D-limonene, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the stirring dead angle. Set the stirring speed to 300r / min, and then add 1L of N,N-dimethylpropylene urea every 20min for 7 times. Set the swelling time to 5h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated product is sieved with a mesh of 5 to obtain solid-state battery cells and a primary separation liquid.

[0062] Step 3: Degumming and cleaning with alkaline alcohol solution

[0063] Add 40 g of sodium hydroxide to 10 L of n-hexanol in another container, stir evenly to obtain an alkaline alcohol solution, heat to 180°C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 300 r / min, the reaction time is 200 min, remove the residual EVA on the surface of the battery cell, debond after alkaline hydrolysis and saponification, clean the surface of the battery cell, separate the battery cell into solid and liquid through a cyclone separator, and obtain the alkaline alcohol solution degummed battery cell and secondary separation liquid. First, use anhydrous ethanol to clean the organic components on the surface of the alkaline alcohol solution degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the alkaline alcohol solution degummed battery cell to obtain a clean battery cell.

[0064] Step 4: Recover the potion

[0065] The primary separation liquid and the secondary separation liquid are respectively sent to the vacuum dryer to recover the organic solvent and the reagent is recycled.

[0066] Based on Example 1, control experiments were carried out, specifically Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4, as described below:

[0067] Comparative Example 1: This comparative example involves a process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method. The only difference from Example 1 is that the degumming solvent used in this comparative example is only D-limonene, and does not contain N,N-dimethylpropylene urea. Specifically:

[0068] Step 1: PV panel pretreatment

[0069] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 1cm×1cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0070] Step 2: Green mixed solvent degumming

[0071] Heat the green mixed solvent oil bath in the container to 60°C, add 500 pre-treated retired photovoltaic modules into 10L of D-limonene, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the dead angle of stirring. Set the stirring speed to 100r / min and the swelling time to 3h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated products are sieved with a sieve with a mesh size of 5 to obtain solid-state battery cells and primary separation liquid.

[0072] Step 3: Degumming and cleaning with alkaline alcohol solution

[0073] Add 40 g of sodium hydroxide to 10 L of n-hexanol in another container, stir evenly to obtain an alkaline alcohol solution, heat to 30°C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 100 r / min, the reaction time is 10 min, remove the residual EVA on the surface of the battery cell, debond after alkaline hydrolysis and saponification, clean the surface of the battery cell, separate the battery cell into solid and liquid through a cyclone separator, and obtain the alkaline alcohol solution degummed battery cell and secondary separation liquid. First, use anhydrous ethanol to clean the organic components on the surface of the alkaline alcohol solution degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the alkaline alcohol solution degummed battery cell to obtain a clean battery cell.

[0074] Step 4: Recover the potion

[0075] The primary separation liquid and the secondary separation liquid are respectively sent to the vacuum dryer to recover the organic solvent and the reagent is recycled.

[0076] Comparative Example 2: This comparative example involves a process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method. The only difference from Example 1 is that the degumming solvent used in this comparative example is only N,N-dimethylpropylene urea, and does not contain D-limonene. Specifically:

[0077] Step 1: PV panel pretreatment

[0078] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 1×1 cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0079] Step 2: Green mixed solvent degumming

[0080] Heat the green mixed solvent oil bath in the container to 60°C, add 500 pre-treated retired photovoltaic modules into 10L of N,N-dimethylpropylene urea, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the stirring dead angle. Set the stirring speed to 100r / min and the swelling time to 3h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated products are sieved with a sieve with a mesh size of 5 to obtain solid-state battery cells and primary separation liquid.

[0081] Step 3: Degumming and cleaning with alkaline alcohol solution

[0082] Add 40 g of sodium hydroxide to 10 L of n-hexanol in another container, stir evenly to obtain an alkaline alcohol solution, heat to 30°C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 100 r / min, the reaction time is 10 min, remove the residual EVA on the surface of the battery cell, debond after alkaline hydrolysis and saponification, clean the surface of the battery cell, separate the battery cell into solid and liquid through a cyclone separator, and obtain the alkaline alcohol solution degummed battery cell and secondary separation liquid. First, use anhydrous ethanol to clean the organic components on the surface of the alkaline alcohol solution degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the alkaline alcohol solution degummed battery cell to obtain a clean battery cell.

[0083] Step 4: Recover the potion

[0084] The primary separation liquid and the secondary separation liquid are respectively sent to the vacuum dryer to recover the organic solvent and the reagent is recycled.

[0085] Comparative Example 3: This comparative example involves a process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method. The only difference from Example 1 is that this comparative example uses sodium hydroxide aqueous solution for degumming and cleaning. Specifically:

[0086] Step 1: PV panel pretreatment

[0087] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 1cm×1cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0088] Step 2: Green mixed solvent degumming

[0089] Heat the green mixed solvent oil bath in the container to 60°C, add 500 pre-treated retired photovoltaic modules into 3L of D-limonene, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the stirring dead angle. Set the stirring speed to 100r / min, and then add 1L of N,N-dimethylpropylene urea every 20min for 7 times. Set the swelling time to 3h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated product is sieved with a sieve with a mesh size of 5 to obtain solid-state battery cells and a primary separation liquid.

[0090] Step 3: Degumming and cleaning with sodium hydroxide solution

[0091] Add 40 g of sodium hydroxide to 10 L of deionized water in another container, stir evenly to obtain an alkaline alcohol solution, heat to 30 ° C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 100 r / min, the reaction time is 10 min, remove the residual EVA on the surface of the battery cell, debond after alkaline hydrolysis and saponification, clean the surface of the battery cell, separate the battery cell into solid and liquid by a cyclone separator, and obtain the sodium hydroxide solution degummed battery cell. First, use anhydrous ethanol to clean the organic components on the surface of the sodium hydroxide solution degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the sodium hydroxide solution degummed battery cell to obtain a clean battery cell.

[0092] Step 4: Recover the potion

[0093] The primary separated liquid is sent to a vacuum dryer to recover the organic solvent and the reagent for recycling.

[0094] Comparative Example 4: This comparative example involves a process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method. The only difference from Example 1 is that this comparative example uses n-hexanol for degumming and cleaning. Specifically:

[0095] Step 1: PV panel pretreatment

[0096] The collected retired photovoltaic modules are framed with a robotic arm, and then the surface glass is crushed with a grinder to fully expose the EVA close to the glass. The modules are then cut into 1cm×1cm pieces using a shear to obtain pre-treated retired photovoltaic modules.

[0097] Step 2: Green mixed solvent degumming

[0098] Heat the green mixed solvent oil bath in the container to 60°C, add 500 pre-treated retired photovoltaic modules into 3L of D-limonene, start stirring, and the stirring paddle should adopt a multi-level structure in the vertical direction to reduce the stirring dead angle. Set the stirring speed to 100r / min, and then add 1L of N,N-dimethylpropylene urea every 20min for 7 times. Set the swelling time to 3h. After swelling, send the components to the cyclone separator for solid-liquid separation. The separated product is sieved with a sieve with a mesh size of 5 to obtain solid-state battery cells and a primary separation liquid.

[0099] Step 3: Hexanol degumming and cleaning

[0100] Heat 10L of n-hexanol in another container to 30°C in an oil bath, add the solid-state battery cell obtained in the previous step, start stirring, the stirring speed is 100r / min, the reaction time is 10min, remove the residual EVA on the surface of the battery cell, clean the surface of the battery cell, separate the battery cell into solid and liquid through a cyclone separator, and obtain the n-hexanol degummed battery cell and secondary separation liquid. First use anhydrous ethanol to clean the organic components on the surface of the n-hexanol degummed battery cell, and then use deionized water to remove the inorganic ions on the surface of the n-hexanol degummed battery cell to obtain a clean battery cell.

[0101] Step 4: Recover the potion

[0102] The primary separation liquid and the secondary separation liquid are respectively sent to the vacuum dryer to recover the organic solvent and the reagent is recycled.

[0103] Detection experiment:

[0104] EVA separation rate detection: select an equal amount of photovoltaic modules and use an X-ray fluorescence spectrometer (XRF) to measure the EVA content in the modules. Remove the EVA on the surface of the photovoltaic modules according to the processes of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 to obtain clean battery cells, measure the EVA content again, and calculate the EVA separation rate.

[0105]

[0106] Conclusion: After the EVA separation rate detection experiment, it can be seen from the data of Comparative Example 1, Comparative Example 2 and Example 1 that the mixed solvent obtained by compounding D-limonene and N,N-dimethylpropylene urea used in the present process can penetrate and swell the EVA in the photovoltaic module, thereby realizing the separation of EVA and achieving the purpose of recycling the photovoltaic module. It can be seen from the data of Comparative Example 3, Comparative Example 4 and Example 1 that the alkaline alcohol solution obtained by compounding sodium hydroxide and n-hexanol used in the present process can wash away the EVA on the surface of the photovoltaic module through saponification reaction, further separate the EVA on the surface of the photovoltaic module, and increase the separation rate of EVA.

[0107] After the process is applied, when the components in the photovoltaic modules are recycled, the silver recovery rate is more than 99.99%, the EVA removal rate is more than 99.5%, the aluminum recovery rate is 100%, and the glass recovery rate is more than 99%. In addition, the process has low energy consumption, high efficiency, is environmentally friendly, and has a good prospect for industrial application.

[0108] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A green mixed agent for efficiently separating retired photovoltaic modules at low temperature, characterized by: The green mixed agent is prepared by accurately mixing N,N-dimethylpropylene urea and D-limonene in a volume ratio of 0.1:10 to 10:0.

1.

2. According to claim 1, a green mixed agent for efficiently separating retired photovoltaic modules at low temperature, characterized in that: The preparation method of the green mixed agent is: Calculated by volume fraction, N,N-dimethylpropylene urea is added to D-limonene which accounts for 20-40% of the total volume of the green mixed agent. The amount added each time is 5-15% of the total volume of the green mixed agent. The interval between each addition is 15-25 minutes. After the addition of N,N-dimethylpropylene urea is completed, the reaction is continued for 1-7 hours to obtain a green mixed agent.

3. A process for efficiently separating retired photovoltaic modules based on a low-temperature green reagent method, characterized in that: Specifically: Step 1: pre-processing retired photovoltaic modules to obtain pre-processed retired photovoltaic modules; Step 2: Heat the green mixed reagent to 60-300°C, add it into the pre-treated retired photovoltaic modules, fully infiltrate and swell them, and separate the solid-liquid into solid-state cells; Step 3: Heat the alkaline alcohol solution to 30-200°C, add the solid battery cell, fully wash it, separate the solid and liquid, and then wash it with anhydrous ethanol and deionized water to obtain a clean battery cell; Step 4: Recover the reagent from the separated liquid after solid-liquid separation in the above two steps.

4. According to claim 3, a process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method is characterized in that: The pretreatment of retired photovoltaic modules is as follows: first, mechanically dismantle the frame of the retired photovoltaic modules, then mechanically grind off the glass on the surface of the photovoltaic modules, and cut them into pieces of (1cm×1cm) to (10cm×10cm) to obtain pretreated retired photovoltaic modules.

5. The process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method according to claim 3 is characterized in that: During the infiltration and swelling process, the added area of ​​the pre-treated retired photovoltaic modules and the volume ratio of the green mixed agent are (5m 2 :1m 3 )~(100m 2 :1m 3 ).

6. The process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method according to claim 3 is characterized in that: Stirring is required during the pretreatment of retired photovoltaic modules during infiltration and swelling. The stirring speed is set to 10 to 1000 rpm and the infiltration and swelling time is 1 to 10 hours.

7. The process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method according to claim 3 is characterized in that: The alkaline alcohol solution consists of sodium hydroxide and n-hexanol, and the concentration of sodium hydroxide is 1g-5g / L.

8. The process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method according to claim 7 is characterized in that: The ratio of the mass of sodium hydroxide in the alkaline alcohol solution to the area of ​​the pretreated decommissioned PV modules is 10 g / m 2 ~1000g / m 2 .

9. The process for efficiently separating retired photovoltaic modules based on a low-temperature green agent method according to claim 3 is characterized in that: In step 3, when washing with the alkaline alcohol solution, the stirring speed is set to 50 to 1000 rpm, and the washing time is 10 to 300 minutes.

Images