High-efficiency photovoltaic module material recovery method based on supercritical fluid

Abstract

The invention relates to an efficient photovoltaic module metal resource recovery method based on supercritical fluid, and aims to realize environment-friendly recovery of high-value metals such as silver, copper and aluminum in a photovoltaic module. According to the invention, supercritical carbon dioxide (CO2) is adopted as a green solvent, and an organic auxiliary agent and a coordination agent are added, so that the metal dissolving capacity is enhanced. The process comprises the steps of assembly crushing, supercritical extraction, pressure regulation and control, metal deposition and the like, and selective recovery of different metals is achieved by optimizing temperature and pressure conditions. According to the method, waste liquid pollution of a traditional acid-alkali method is avoided, the energy consumption is low, the recovery rate is high, supercritical CO2 can be recycled, and the cost and the environmental influence are reduced. The process can be widely applied to metal resource recovery of photovoltaic modules and other electronic wastes, and an innovative solution is provided for realizing green economy and sustainable development.

Description

Technical Field

[0001] The present invention relates to the technical field of waste treatment, and more particularly to a method for efficiently recycling photovoltaic component materials based on supercritical fluid. Background Art

[0002] With the rapid development of the global electronics industry and renewable energy industry, the use of photovoltaic modules has increased year by year. However, the service life of photovoltaic modules is usually between 20 and 25 years. As a large number of modules gradually enter the scrap cycle, a large amount of electronic waste is generated. Photovoltaic module waste mainly includes glass, plastic layers, silicon wafers, and metal conductor materials such as copper, aluminum, and silver. If the accumulation of these wastes is not handled properly, it will cause serious pollution to the environment and lead to the waste of precious resources. Therefore, it is particularly important to recycle photovoltaic modules efficiently and environmentally friendly.

[0003] Shortcomings of existing recycling technologies

[0004] Currently, metal resources in photovoltaic modules are mostly recovered by traditional recycling technologies such as roasting, acid-base wet leaching and mechanical sorting. However, these methods have many defects:

[0005] 1. High energy consumption and high pollution: The traditional roasting process needs to be operated under high temperature conditions, which consumes a lot of energy and emits harmful exhaust gas, increasing the risk of environmental pollution.

[0006] 2. Large amount of acid and alkali used: Wet leaching often requires a large amount of acid and alkali solution, the waste liquid treatment process is complicated, which increases the operating cost and may cause secondary pollution.

[0007] 3. Unstable recycling efficiency: The recycling efficiency of some metals (such as silver and copper) in traditional processes is low and cannot meet the needs of large-scale industrial applications.

[0008] 4. Poor economic efficiency: Traditional processes usually require complex equipment and multi-step processes, resulting in high overall costs and are not suitable for large-scale industrial promotion.

[0009] Therefore, an environmentally friendly and efficient recycling process is needed to replace the traditional method. Summary of the invention

[0010] In order to solve the above problems, the present invention provides a method for efficiently recovering metal resources from photovoltaic modules based on supercritical fluid. The method uses a composite solvent system formed by supercritical carbon dioxide and an additive to efficiently extract metals from photovoltaic modules under suitable pressure and temperature conditions, and achieves high-purity recovery and recycling of metal resources through multi-stage separation, tail gas treatment and material reprocessing.

[0011] The present invention provides the following technical solution, which mainly includes:

[0012] A method for efficiently recycling photovoltaic module materials based on supercritical fluid comprises the following steps:

[0013] Disassembly and pretreatment of S1 photovoltaic modules:

[0014] Dismantle the waste photovoltaic modules, remove the aluminum frame, back panel and connectors, and cut the internal electrode layer into small pieces suitable for further processing.

[0015] S2 Supercritical Fluid Processing:

[0016] The pretreated components are placed in a reactor, carbon dioxide is injected, the carbon dioxide is pressurized to 8-10MPa through a liquefaction pump, and the temperature is controlled at 40-50°C to reach a supercritical state.

[0017] S3 additive addition and metal extraction:

[0018] Adding additives such as ethanol, methanol or amino compounds to supercritical carbon dioxide forms a composite solvent system with carbon dioxide. The composite solvent system fully penetrates the component materials in the reactor to achieve metal dissolution and extraction.

[0019] S4 multi-stage separation and metal recovery:

[0020] By releasing the pressure, the supercritical carbon dioxide is gasified and separated from the dissolved metal. The separated metal solution is processed by filtering equipment to obtain metal precipitates such as silver, copper, and aluminum.

[0021] S5 magnetic separation and classification:

[0022] The recovered metal precipitate is further classified by magnetic separation equipment to separate ferromagnetic materials, precious metals and non-precious metals.

[0023] S6 tail gas treatment and carbon dioxide recycling:

[0024] The tail gas is treated by an adsorption device to remove residual additives and harmful gases. The gaseous carbon dioxide is converted into liquid through a condensation device and stored in a high-pressure tank for recycling.

[0025] S7 material reprocessing and utilization:

[0026] Recycled metal materials are smelted into high-purity metals, and glass and silicon wafers are reprocessed to produce new photovoltaic modules, realizing the recycling of resources.

[0027] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) Efficient metal recovery: Through the high permeability of supercritical fluid, efficient extraction of metals such as silver, copper and aluminum in photovoltaic modules is achieved, with a metal recovery rate of more than 95%.

[0029] (2) Environmentally friendly and pollution-free: Using supercritical carbon dioxide as a solvent avoids acid and alkali pollution in traditional hydrometallurgy and achieves green and environmentally friendly treatment.

[0030] (3) Recycling of additives: The additives and carbon dioxide in the composite solvent system can be recycled, which greatly reduces the processing cost.

[0031] (4) Reduce energy consumption: Supercritical fluid processing has lower temperature and pressure, which greatly reduces energy consumption compared to traditional high-temperature incineration processes.

[0032] (5) Resource recycling: Recycled metal and non-metal materials can be used in the production of new photovoltaic modules, achieving closed-loop utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0036] like Figure 1 As shown, the present invention proposes a method for efficiently recovering metal resources of photovoltaic modules based on supercritical fluid, comprising the following steps:

[0037] S1 disassembly and pretreatment of photovoltaic modules, S2 supercritical fluid processing, S3 additive addition and metal extraction, S4 multi-stage separation and metal recovery, S5 magnetic separation and classification, S6 tail gas treatment and carbon dioxide recycling and S7 material reprocessing and utilization;

[0038] Through the supercritical carbon dioxide and additive composite solvent system, the metal resources in the photovoltaic modules are extracted at a pressure of 8-10MPa and a temperature of 40-50°C, and the recycling of carbon dioxide and additives is achieved.

[0039] Preferably, the disassembly and preprocessing step includes separating the aluminum frame, back plate and connectors in the photovoltaic module from the internal electrode layer and cutting them into a size suitable for processing.

[0040] Preferably, in the supercritical fluid treatment step, carbon dioxide is injected into the reactor using a liquefaction pump and gradually pressurized to 8-10 MPa to make the carbon dioxide reach a supercritical state and improve its permeability to the packaging material.

[0041] Preferably, the auxiliary agent is ethanol, methanol or an amino compound, which forms a composite solvent system with supercritical carbon dioxide to enhance the solubility of metal materials such as silver, copper and aluminum.

[0042] Preferably, during the metal extraction process, the composite solvent system is kept uniformly dispersed in the reactor by stirring, so that the metal in the internal electrode material is effectively dissolved into the supercritical fluid.

[0043] Preferably, the multi-stage separation process releases pressure to gasify the supercritical carbon dioxide, and the metal particles are separated from the additives and then enter a filtering device to recover the metal precipitate.

[0044] Preferably, the separated metal materials are further classified by magnetic separation equipment to separate and collect non-precious metals such as copper and aluminum from precious metals such as silver.

[0045] Preferably, in the tail gas treatment step, a tail gas adsorption device is used to remove residual additives and harmful gases, and ensure that the exhaust gas meets environmental protection standards.

[0046] Preferably, the carbon dioxide recycling step converts gaseous carbon dioxide into liquid through a condensation device and stores it in a high-pressure tank for subsequent use.

[0047] Preferably, the material reprocessing step includes re-smelting the recovered metal materials to prepare high-purity metals, and reprocessing the glass and silicon wafers for producing new photovoltaic modules.

[0048] Example 1: High-efficiency recycling process of metal resources from photovoltaic modules based on supercritical fluid

[0049] Implementation Environment Preparation

[0050] This example uses disassembled photovoltaic modules as the processing object, and uses supercritical carbon dioxide and ethanol to form a composite solvent system to achieve efficient metal recovery under controlled temperature and pressure conditions. The specific experimental equipment includes:

[0051] Reactor (high pressure vessel, maximum pressure 20MPa)

[0052] Liquefaction pump (for carbon dioxide pressurization)

[0053] Magnetic separator (for sorting and separation of metals)

[0054] Adsorption tower and condensation equipment (for tail gas treatment and carbon dioxide circulation)

[0055] High-purity carbon dioxide and anhydrous ethanol are used as the main process solvents.

[0056] 1. Pretreatment of photovoltaic modules

[0057] Dismantle the waste photovoltaic modules. The specific process includes:

[0058] (1) Disassembly of aluminum frame and back panel: Use cutting equipment to remove the external structure of the photovoltaic module, including the aluminum frame and plastic back panel.

[0059] (2) Processing of the silicon wafer electrode layer: The electrode layer and the internal glass substrate are cut into small pieces of 10 × 10 cm to facilitate the subsequent extraction process.

[0060] (3) Waste partition storage: The cut component blocks are divided into metal-enriched parts (such as electrode layers containing silver and copper) and non-metallic parts (glass, plastic, etc.), and processed separately.

[0061] 2. Supercritical fluid processing steps

[0062] Place the cut photovoltaic module blocks into the reactor and perform supercritical fluid treatment according to the following steps:

[0063] (1) Carbon dioxide pressurization and temperature control

[0064] A liquefaction pump is used to inject carbon dioxide into the reactor and raise its pressure to 9MPa. At the same time, the temperature is controlled at 45°C to ensure that the carbon dioxide is in a supercritical state. Under this condition, carbon dioxide exhibits the dual characteristics of liquid and gas, with high permeability and solubility.

[0065] (2) Addition of additives

[0066] 10% anhydrous ethanol of the volume of supercritical carbon dioxide is added to the reaction kettle as an auxiliary agent. Ethanol forms a composite solvent system with carbon dioxide in a supercritical state, which enhances the solubility of metals (such as silver, copper, and aluminum).

[0067] (3) Dissolution and extraction of metals

[0068] Under the action of the composite solvent, the silver, copper and aluminum in the component blocks gradually dissolved. The reaction process lasted for 30 minutes to ensure that the metals were fully exposed to the solvent and completely extracted.

[0069] 3. Separation and recovery of metals after extraction

[0070] (1) Pressure release and metal precipitation

[0071] After the metal is dissolved, the pressure in the reactor is slowly released to convert the supercritical carbon dioxide into a gaseous state. As the gas is released, the dissolved metal precipitates out as a precipitate and is collected in a filter.

[0072] (2) Magnetic separation

[0073] Use magnetic separation equipment to classify metal precipitates. Magnetic separation can separate ferromagnetic materials from non-magnetic metals (such as silver, copper, and aluminum) to obtain high-purity metals.

[0074] (3) Further classification and storage

[0075] Silver and copper are further purified by chemical precipitation.

[0076] After screening, aluminum can be used directly for smelting or processing.

[0077] 4. Tail gas treatment and carbon dioxide recycling

[0078] (1) Exhaust gas treatment

[0079] The tail gas released in the reactor enters the adsorption tower to remove residual ethanol and harmful components to ensure that the tail gas meets the emission standards.

[0080] (2) Carbon dioxide condensation and storage

[0081] The gaseous carbon dioxide after adsorption treatment enters the condensation equipment, is converted into liquid carbon dioxide and stored in a high-pressure tank for the next cycle.

[0082] 5. Analysis of economic and environmental benefits

[0083] (1) High metal recovery rate: Under the process conditions, the recovery rate of silver reaches 96%, and the recovery rates of copper and aluminum are 93% and 90% respectively.

[0084] (2) Environmental benefits: This process uses supercritical carbon dioxide, which avoids acid and alkali pollution in traditional hydrometallurgical processes. Both carbon dioxide and ethanol can be recycled, reducing waste gas emissions and additive consumption.

[0085] (3) Reduce energy consumption: Since the reaction temperature is controlled at 45°C, a lot of energy is saved compared to traditional high-temperature treatment processes.

[0086] Example 2: Effects of different temperatures, pressures and dissolution times on metal recovery

[0087] In order to further optimize the metal recovery process of photovoltaic modules using supercritical fluid, this embodiment conducts a detailed study on the effects of multiple factors such as temperature, pressure, and dissolution time on the recovery rate.

[0088] Experimental conditions

[0089] -Solvent: Supercritical Carbon Dioxide (CO2)

[0090] - Additives: organic solvents and complexing agents (such as ethanol, acetic acid, etc.)

[0091] -Metal Type: Silver, Copper, Aluminum

[0092] - Temperature range: 35℃, 45℃, 55℃

[0093] -Pressure range: 8MPa, 9MPa, 10MPa

[0094] -Dissolution time: 15 minutes, 30 minutes, 45 minutes

[0095] Experimental procedures

[0096] 1. Cut the metal sheets of the photovoltaic modules and place them in a reactor, and add additives and supercritical CO2.

[0097] 2. Set the temperature (35°C, 45°C, 55°C), pressure (8MPa, 9MPa, 10MPa), and different dissolution times (15 minutes, 30 minutes, 45 minutes) respectively.

[0098] 3. After each experiment, the dissolved liquid is cooled and separated, and the recovery rate and purity of the metal are measured.

[0099] Experimental data table: Recycling performance under different parameters

[0100]

[0101] Experimental results analysis

[0102] 1. Effect of temperature: At 35°C, the recovery rate of each metal is low, indicating that lower temperature is not conducive to the synergistic effect of additives and supercritical CO2. As the temperature rises to 45°C, the metal recovery rate reaches the highest, especially the silver recovery rate reaches 96%. However, the recovery rate decreases slightly after the temperature rises to 55°C, which may be due to the high temperature causing the additive to volatilize or react too quickly, reducing the metal extraction efficiency.

[0103] 2. Effect of pressure: At 9MPa, supercritical CO2 has the best solubility, so the metal recovery rate is the highest. When the pressure is increased to 10MPa, although the recovery rate remains at a high level, the increased pressure may increase the operating cost.

[0104] 3. Effect of dissolution time: When the dissolution time is extended to 30 minutes, the metal recovery effect is significantly improved. However, after more than 45 minutes, the recovery rate does not change much, indicating that long-term dissolution does not further improve the recovery effect.

[0105] 4. Metal purity: By optimizing temperature and pressure, the purity of the recovered metal can reach over 99%, suitable for subsequent refining or direct application.

[0106] Optimization conclusion

[0107] - Optimum temperature: 45℃

[0108] -Optimum pressure: 9MPa

[0109] - Optimal dissolution time: 30 minutes

[0110] Under this condition, the recovery rate and purity of each metal are optimized, and the economy and efficiency of the process are guaranteed.

[0111] Economic and environmental benefits

[0112] 1. Energy saving and consumption reduction: Compared with the traditional acid-base method, this process uses supercritical CO2, avoids high-temperature roasting or the use of large amounts of acid and alkali, and reduces energy consumption and waste liquid treatment costs.

[0113] 2. Environmentally friendly: Supercritical CO2 can be recycled, reducing pollution to the environment and achieving green production and efficient use of resources.

[0114] 3. High efficiency: This process is suitable for the separation and recovery of various metals in photovoltaic modules, and ensures the high purity of recycled materials, providing a new path for the recycling of electronic waste.

[0115] Through the optimization experiment of this embodiment, the feasibility and efficiency of metal recovery based on supercritical fluid technology are verified, and a reliable technical solution is provided for the green recovery of photovoltaic module materials. The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0116] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for efficiently recovering metal resources from photovoltaic modules based on supercritical fluid, characterized in that: The following steps are involved: S1 disassembly and pretreatment of photovoltaic modules, S2 supercritical fluid processing, S3 additive addition and metal extraction, S4 multi-stage separation and metal recovery, S5 magnetic separation and classification, S6 tail gas treatment and carbon dioxide recycling and S7 material reprocessing and utilization; Through the supercritical carbon dioxide and additive composite solvent system, the metal resources in the photovoltaic modules are extracted at a pressure of 8-10MPa and a temperature of 40-50°C, and the recycling of carbon dioxide and additives is achieved.

2. The recycling method according to claim 1, characterized in that: The disassembly and pre-processing steps include separating the aluminum frame, back sheet and connectors in the photovoltaic module from the internal electrode layer and cutting them into sizes suitable for processing.

3. The recycling method according to claim 1, characterized in that: In the supercritical fluid treatment step, carbon dioxide is injected into the reactor using a liquefaction pump and gradually pressurized to 8-10 MPa to make the carbon dioxide reach a supercritical state and improve its permeability to the packaging material.

4. The recycling method according to claim 1, characterized in that: The auxiliary agent is selected from ethanol, methanol or amino compounds, and forms a composite solvent system with supercritical carbon dioxide to enhance the dissolving ability of metal materials such as silver, copper and aluminum.

5. The recycling method according to claim 1, characterized in that: During the metal extraction process, the composite solvent system is kept uniformly dispersed in the reactor by stirring, so that the metal in the internal electrode material is effectively dissolved into the supercritical fluid.

6. The recycling method according to claim 1, characterized in that: The multi-stage separation process releases pressure to gasify supercritical carbon dioxide, and the metal particles are separated from the additives and then enter the filtering equipment to recover the metal precipitate.

7. The recycling method according to claim 1, characterized in that: The separated metal materials are further classified by magnetic separation equipment to collect non-precious metals such as copper and aluminum separately from precious metals such as silver.

8. The recycling method according to claim 1, characterized in that: In the exhaust gas treatment step, an exhaust gas adsorption device is used to remove residual additives and harmful gases, and ensure that the exhaust gas meets environmental protection standards.

9. The recycling method according to claim 1, characterized in that: The CO2 recycling step converts gaseous CO2 into liquid form through a condensation device and stores it in a high-pressure tank for subsequent use.

10. The recycling method according to claim 1, characterized in that: The material reprocessing step includes re-smelting the recovered metal materials to prepare high-purity metals, and reprocessing the glass and silicon wafers for the production of new photovoltaic modules.

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