Method for rapidly and efficiently recycling silver in retired crystalline silicon photovoltaic module

Abstract

The invention discloses a method for rapidly and efficiently recovering silver in a retired crystalline silicon photovoltaic module, and belongs to the technical field of waste recovery. The method comprises the following steps: (1) mechanically disassembling the retired crystalline silicon photovoltaic module to obtain a laminated part; (2) carrying out heat treatment on the laminated piece, and removing the organic packaging material to obtain a crystalline silicon battery piece; (3) sequentially grinding, crushing and screening the crystalline silicon battery piece to obtain crystalline silicon battery piece powder with uniform granularity; and (4) under the vacuum condition, performing flash evaporation Joule heating on the crystalline silicon cell piece powder to vaporize and volatilize silver in the crystalline silicon cell piece powder, and then condensing the volatilized silver gas to obtain silver powder. Based on the crystalline silicon photovoltaic cell piece powder intrinsic resistance, the crystalline silicon cell piece powder is heated in a flash evaporation Joule mode, the silver recovery time is remarkably shortened, the recovery efficiency is improved, and efficient, green and high-recovery-rate recovery of silver in the retired crystalline silicon photovoltaic module is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste recycling, and relates to a method for quickly and efficiently recovering silver from a retired crystalline silicon photovoltaic module. BACKGROUND

[0002] Solar energy, as a clean and renewable energy, plays an important role in the new energy market. According to the prediction, the world's cumulative solar power capacity will exceed coal to become the largest power supply energy in the future.

[0003] A photovoltaic module (solar panel) is a core part of a solar power generation system, which converts solar energy into electrical energy, or stores it in a storage battery, or drives a load to work. In recent years, it has developed rapidly and its use has rapidly grown due to its advantages of high efficiency, safety, easy installation, and obvious economic advantages. The theoretical design life of a photovoltaic module is usually 25-30 years. When the service life of a photovoltaic module reaches the theoretical design life or the performance of the photovoltaic module degrades to the extent that it cannot be used normally, it is retired and becomes a retired photovoltaic module. Crystalline silicon photovoltaic modules are a kind of photovoltaic modules. Due to their high conversion efficiency and stable performance, they have long dominated the photovoltaic market, with a market share of up to 95%. Therefore, retired crystalline silicon photovoltaic modules are the main object of photovoltaic waste disposal.

[0004] Retired crystalline silicon photovoltaic modules contain various valuable components (such as silver, silicon, etc.) and harmful components (such as organic packaging materials, heavy metals, etc.). If they are disposed of by landfill, storage, etc., not only will a large amount of land be occupied, but also environmental pollution will be caused, and resources will be wasted. The average silver content in retired crystalline silicon photovoltaic modules is about 630 g / t, which is close to the silver content in primary silver ore (about 700 g / t). Recovering silver from retired crystalline silicon photovoltaic modules can reduce the amount of primary silver ore mining and slow down the speed of resource depletion. In addition, the structure of retired crystalline silicon photovoltaic modules is simpler than that of primary silver ore. Compared with extracting silver from primary silver ore, recovering silver from retired crystalline silicon photovoltaic modules is less difficult, which can effectively reduce the energy consumption and comprehensive cost of obtaining silver. Therefore, it is of great significance to recover silver from retired crystalline silicon photovoltaic modules.

[0005] Currently, a wet recovery process is widely used to recover silver from decommissioned crystalline silicon photovoltaic modules. However, due to the high chemical inertness of silver, the wet recovery process needs to rely on a strong acid system (such as HCl, H2SO4, H3PO4, etc.) or a strong alkali system (such as NaOH, KOH, Ca(OH)2, etc.) and be assisted by an oxidizing agent or other additives for treatment. The use of strong acids, strong alkalis and chemical additives not only releases toxic gases such as SO3, Cl2 and NO, forms harmful and difficult-to-treat waste liquid, causes serious environmental pollution, but also causes severe corrosion of equipment, thereby significantly increasing the recovery cost.

[0006] Although in recent years, the emergence of deep eutectic solvents provides a possibility to improve the environmental friendliness of silver recovery, however, the feature of easy decomposition at high temperature of deep eutectic solvents seriously limits the silver recovery efficiency when recovering silver from decommissioned crystalline silicon photovoltaic modules.

[0007] Therefore, it is necessary to provide a method for quickly and efficiently recovering silver from decommissioned crystalline silicon photovoltaic modules, to realize the quick and efficient green recovery of silver from decommissioned crystalline silicon photovoltaic modules, and to significantly improve the silver recovery efficiency while maintaining a high silver recovery rate. SUMMARY

[0008] In order to overcome the problems in the background art, the present application utilizes the intrinsic resistance characteristics of the material, realizes instantaneous heating through flash Joule heating, and based on the high saturated vapor pressure of silver in the material, makes the silver in the decommissioned crystalline silicon photovoltaic module quickly volatilize and condense and enrich, thereby realizing the quick and efficient recovery of silver from decommissioned crystalline silicon photovoltaic modules. At the same time, no chemical reagents are needed in the recovery process, and the process has high environmental friendliness.

[0009] In order to achieve the above purpose, the present application realizes the following technical scheme: The present application provides a method for quickly and efficiently recovering silver from decommissioned crystalline silicon photovoltaic modules, which comprises the following steps: (1) Mechanically disassembling the decommissioned crystalline silicon photovoltaic module to obtain a laminated piece.

[0010] (2) Heat treating the laminated piece obtained in step (1) to remove the organic packaging material and obtain a crystalline silicon cell piece.

[0011] The crystalline silicon cell piece in the decommissioned crystalline silicon photovoltaic module mainly contains three metals: silicon, aluminum and silver, and the content of silver is usually in the range of 0.2% to 1.5%.

[0012] (3) Grind and crush the crystalline silicon cell piece obtained in step (2) in sequence, and sieve to obtain a crystalline silicon cell piece powder with uniform particle size.

[0013] The intrinsic resistance of the crystalline silicon cell piece powder is usually 2 to 4 Ω.

[0014] (4) under vacuum, flash Joule heating is performed on the crystalline silicon cell piece powder obtained in step (3) to make the silver in the crystalline silicon cell piece powder vaporize, and then the vaporized silver gas is condensed to obtain silver powder.

[0015] Preferably, in step (1), the aluminum frame and junction box of the decommissioned crystalline silicon photovoltaic module are mechanically disassembled.

[0016] Preferably, in step (2), the laminated piece is heat treated in an argon atmosphere.

[0017] Preferably, in step (2), the heat treatment temperature is 550-650℃, and the heat treatment time is 60 min.

[0018] In step (3), the crystalline silicon cell piece is ground and crushed to a particle size of 200 mesh.

[0019] The crystalline silicon cell piece is ground and crushed using a Raymond mill, and the particle size of the ground and crushed powder is controlled by adjusting the speed of the classifier of the mill, the roller pressure, and the air volume of the fan. The speed of the classifier is set to 200 rpm, the roller pressure is controlled at 60% of the spring pre-tightening force, and the air volume of the fan is adjusted to medium air volume by setting the damper opening to 55%.

[0020] Preferably, in step (3), the mesh size of the screen used for sieving is 200 mesh.

[0021] Since the accuracy of the powder particle size control during the grinding and crushing process cannot be guaranteed to be 100%, the use of a screen for sieving further improves the uniformity of the powder particle size.

[0022] Preferably, in step (4), the vacuum degree is 10 1 ~10 5 Pa.

[0023] Preferably, in step (4), the number of flash Joule heating is 1-5 times, the voltage applied each time is the same and is 100-180V, and the heating time each time is 500ms-1s.

[0024] Preferably, the decommissioned crystalline silicon photovoltaic module is a single-crystal or polycrystalline silicon solar cell panel that has reached the end of its service life or has been retired due to performance degradation. The tempered glass and crystalline silicon cell piece in such a solar cell panel are usually not broken and can be obtained in a relatively complete state.

[0025] Advantages of the present application: 1. The present application realizes instantaneous temperature rise and rapid heating under the action of high-power electric pulse by using flash Joule heating, significantly shortens the time required for silver recovery, and effectively improves the silver recovery efficiency.

[0026] 2. In the present application, no chemical reagent is required in the recovery process, effectively reducing or even avoiding the generation of harmful waste liquid and gas, and having high environmental friendliness.

[0027] 3. The silver recovery rate of the present application can reach 92%, realizing efficient and green recovery while ensuring high silver recovery rate, and the comprehensive recovery effect is excellent.

[0028] 4. The process flow of the present application is simple and easy to implement, and is suitable for industrialization and application. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a flowchart of the method of the present application; Figure 2 is a schematic diagram of the flash Joule heating and cooling equipment of the present application; In the figure, 1 is a graphite electrode, 2 is a reaction cavity, 3 is a porous copper electrode, 4 is a vacuum pumping system, and 5 is a cold trap system. Figure 3 is a trend chart of voltage, current and temperature change with time in the flash Joule heating of Example 1 of the present application, wherein (a) is a trend chart of voltage and current change with time, and (b) is a trend chart of temperature change with time. Figure 4 is a physical diagram of recovered silver in Example 1 of the present application, wherein (a) is a macrograph, and (b) is a micrograph. Figure 5 is a phase analysis chart of the recovered silver in Example 1 of the present application. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below in combination with the drawings and specific examples, but the scope of protection of the present application is not limited to the described content.

[0031] Example 1 In this example, silver is recovered from the retired crystalline silicon photovoltaic module by the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are disassembled by mechanical method to obtain a laminated part. The laminated part is composed of, from top to bottom, tempered glass, EVA organic packaging material, crystalline silicon cell, EVA organic packaging material and TPT organic packaging material.

[0032] (2) The laminated part is heat treated at 600℃ for 60min to completely pyrolyze and remove the organic packaging material in the laminated part, and the tempered glass and crystalline silicon cell are separated to obtain the crystalline silicon cell.

[0033] (3) Use a Raymond mill (set its classifier speed to 200 rpm, control the roller pressure to 60% of the spring preload, and adjust the fan airflow to medium airflow at 55% of the damper opening) to grind and pulverize the crystalline silicon solar cell to 200 mesh, and then sieve out the 200 mesh crystalline silicon solar cell powder through mechanical screening.

[0034] (4) Place the crystalline silicon solar cell powder in a flash evaporation Joule heating device (e.g., Figure 2 In the reaction chamber shown, a vacuum was drawn until the system pressure reached 10. 1 Pa. Liquid nitrogen cooling was used to maintain the temperature of the cold trap system at -150℃. The applied voltage, heating time, and number of flash evaporation cycles of the flash Joule heating equipment were precisely controlled. The applied voltage was set to 120V, and the heating time was set to 1s. The flash Joule heating equipment was started to perform flash Joule heating treatment on the crystalline silicon solar cell powder, and the above flash Joule heating was repeated twice, for a total of three flash Joule heating cycles. Based on the intrinsic resistance characteristics, the crystalline silicon solar cell powder generated a violent Joule heating effect under the action of instantaneous high-power electric pulses, and the temperature instantly rose to 1500℃ within 1s. The silver in the crystalline silicon solar cell powder underwent a vaporization transformation. The volatilized gaseous silver entered the -150℃ cold trap system and underwent directional condensation, transforming into silver powder, which was then recovered and reused. This achieved rapid and efficient recovery of silver from retired crystalline silicon photovoltaic modules, with a silver recovery rate of 92%.

[0035] The voltage, current, and temperature changes during the flash Joule heating process in this embodiment were measured, and the results are as follows: Figure 3 As shown.

[0036] pass Figure 3 (a) It can be seen that the maximum voltage during the flash Joule heating process is the set value of 120V and the maximum current is 255A.

[0037] pass Figure 3 (b) It can be seen that the maximum temperature during the flash Joule heating process is 1500℃, and the entire heating and cooling process is completed within 1 second.

[0038] The silver recovered in this embodiment was observed, and the results are as follows: Figure 4 As shown.

[0039] pass Figure 4 (a) It can be seen that the silver was recovered in the form of a grayish-white powder.

[0040] pass Figure 4 (b) It can be seen that the recovered silver is distributed in clusters.

[0041] Phase analysis was performed on the silver recovered in this embodiment, and the results are as follows: Figure 5 As shown.

[0042] pass Figure 5 It can be seen that the recovered silver mainly exists in elemental form.

[0043] In summary, this invention achieves rapid heating and cooling of crystalline silicon solar cell powder to 1500°C within 2 seconds using a high-power instantaneous electrical pulse (maximum voltage: 120V, maximum current: 255A). The silver in the crystalline silicon solar cell powder undergoes rapid vaporization and condensation, and is successfully recovered in the cold trap system. The recovered silver is a grayish-white elemental silver powder exhibiting a clustered distribution.

[0044] Example 2 This embodiment recovers silver from decommissioned crystalline silicon photovoltaic modules using the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are mechanically disassembled to obtain the laminate. The laminate consists of tempered glass, EVA organic encapsulation material, crystalline silicon solar cell, EVA organic encapsulation material and TPT organic encapsulation material from top to bottom.

[0045] (2) The laminate is heat-treated at 600℃ for 60 minutes to completely remove the organic encapsulation material in the laminate by thermal decomposition, and the tempered glass and crystalline silicon solar cell are separated to obtain the crystalline silicon solar cell.

[0046] (3) Use a Raymond mill (set its classifier speed to 200 rpm, control the roller pressure to 60% of the spring preload, and adjust the fan airflow to medium airflow at 55% of the damper opening) to grind and pulverize the crystalline silicon solar cell to 200 mesh, and then sieve out the 200 mesh crystalline silicon solar cell powder through mechanical screening.

[0047] (4) Place the crystalline silicon solar cell powder in a flash evaporation Joule heating device (e.g., Figure 2 In the reaction chamber shown, a vacuum was drawn until the system pressure reached 10. 5 Pa. Liquid nitrogen cooling was used to maintain the temperature of the cold trap system at -200℃. The applied voltage, heating time, and number of flash evaporation cycles of the flash Joule heating equipment were precisely controlled. The applied voltage was set to 180V, and the heating time was set to 500ms. The flash Joule heating equipment was started to perform flash Joule heating treatment on the crystalline silicon solar cell powder, and the above flash Joule heating was repeated 4 times, for a total of 5 flash Joule heating cycles. Based on the intrinsic resistance characteristics, the crystalline silicon solar cell powder generated a violent Joule heating effect under the action of instantaneous high-power electric pulses, and the temperature instantly rose to 3000℃ within 500ms. The silver in the crystalline silicon solar cell powder underwent a vaporization transformation. The volatilized gaseous silver entered the -200℃ cold trap system and underwent directional condensation, transforming into silver powder, which was then recovered and reused. This achieved rapid and efficient recovery of silver from retired crystalline silicon photovoltaic modules, with a silver recovery rate of 74%.

[0048] Example 3 This embodiment recovers silver from decommissioned crystalline silicon photovoltaic modules using the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are mechanically disassembled to obtain the laminate. The laminate consists of tempered glass, EVA organic encapsulation material, crystalline silicon solar cell, EVA organic encapsulation material and TPT organic encapsulation material from top to bottom.

[0049] (2) The laminate is heat-treated at 650℃ for 60 min to completely remove the organic encapsulation material in the laminate by thermal decomposition, and the tempered glass and crystalline silicon solar cell are separated to obtain crystalline silicon solar cell.

[0050] (3) Use a Raymond mill (set its classifier speed to 200 rpm, control the roller pressure to 60% of the spring preload, and adjust the fan airflow to medium airflow at 55% of the damper opening) to grind and pulverize the crystalline silicon solar cell to 200 mesh, and then sieve out the 200 mesh crystalline silicon solar cell powder through mechanical screening.

[0051] (4) Place the crystalline silicon solar cell powder in a flash evaporation Joule heating device (e.g., Figure 2 In the reaction chamber shown, a vacuum was drawn until the system pressure reached 10. 1 Pa. Liquid nitrogen cooling was used to maintain the temperature of the cold trap system at -150℃. The applied voltage, heating time, and number of flash evaporation cycles of the flash Joule heating equipment were precisely controlled. The applied voltage was set to 140V, and the heating time was set to 1s. The flash Joule heating equipment was started to perform flash Joule heating treatment on the crystalline silicon solar cell powder. A total of one flash Joule heating was performed. Based on its intrinsic resistance characteristics, the crystalline silicon solar cell powder generated a violent Joule heating effect under the action of a transient high-power electric pulse, and the temperature instantly rose to 1900℃ within 1s. The silver in the crystalline silicon solar cell powder underwent a vaporization transformation. The volatilized gaseous silver entered the -150℃ cold trap system and underwent directional condensation, transforming into silver powder, which was then recovered and reused. This achieved rapid and efficient recovery of silver from retired crystalline silicon photovoltaic modules, with a silver recovery rate of 77%.

[0052] Example 4 This embodiment recovers silver from decommissioned crystalline silicon photovoltaic modules using the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are mechanically disassembled to obtain the laminate. The laminate consists of tempered glass, EVA organic encapsulation material, crystalline silicon solar cell, EVA organic encapsulation material and TPT organic encapsulation material from top to bottom.

[0053] (2) heat treatment of the laminated piece at 650℃ for 60 min, completely pyrolyze and remove the organic encapsulating material in the laminated piece, separate the tempered glass and the crystalline silicon cell, and obtain the crystalline silicon cell.

[0054] (3) use a Raymond mill (set the speed of the classifier to 200 rpm, control the roller pressure at 60% of the spring pre-tightening force, and control the air volume of the fan to medium by adjusting the air door opening to 55%) to grind the crystalline silicon cell to 200 mesh, and screen out the 200 mesh crystalline silicon cell powder by mechanical screening.

[0055] (4) place the crystalline silicon cell powder in the reaction cavity of the flash Joule heating device (such as shown in Figure 2 ), and vacuumize to a system pressure of 10 5 Pa. Use liquid nitrogen cooling to maintain the temperature of the cold trap system at -200℃. Accurately control the applied voltage, heating time, and flash times of the flash Joule heating device, set the applied voltage to 150V, and set the heating time to 1s. Start the flash Joule heating device to perform flash Joule heating treatment on the crystalline silicon cell powder, and repeat the aforementioned flash Joule heating 4 times, for a total of 5 times of flash Joule heating. The crystalline silicon cell powder generates intense Joule heating effect under the action of the instantaneous high-power electric pulse based on the intrinsic resistance characteristics, and the temperature instantaneously rises to 2100℃ within 1s. The silver in the crystalline silicon cell powder gasifies and changes, and the volatilized gaseous silver enters the -200℃ cold trap system to undergo directional condensation and change into silver powder, which is then recycled and reused, achieving rapid and efficient recovery of silver from the retired crystalline silicon photovoltaic module. The recovery rate of silver is 71%.

[0056] Example 5 This example recovers silver from a retired crystalline silicon photovoltaic module by the following method: (1) mechanically disassemble the aluminum frame and the junction box of the retired crystalline silicon photovoltaic module to obtain a laminated piece. The laminated piece has, from top to bottom, tempered glass, EVA organic encapsulating material, crystalline silicon cell, EVA organic encapsulating material, and TPT organic encapsulating material.

[0057] (2) heat treatment of the laminated piece at 600℃ for 60 min, completely pyrolyze and remove the organic encapsulating material in the laminated piece, separate the tempered glass and the crystalline silicon cell, and obtain the crystalline silicon cell.

[0058] (3) use a Raymond mill (set the speed of the classifier to 200 rpm, control the roller pressure at 60% of the spring pre-tightening force, and control the air volume of the fan to medium by adjusting the air door opening to 55%) to grind the crystalline silicon cell to 200 mesh, and screen out the 200 mesh crystalline silicon cell powder by mechanical screening.

[0059] (4) Place the crystalline silicon solar cell powder in a flash evaporation Joule heating device (e.g., Figure 2 In the reaction chamber shown, a vacuum was drawn until the system pressure reached 10. 3 Pa. Liquid nitrogen cooling was used to maintain the temperature of the cold trap system at -150℃. The applied voltage, heating time, and number of flash evaporation cycles of the flash Joule heating equipment were precisely controlled. The applied voltage was set to 130V, and the heating time was set to 500ms. The flash Joule heating equipment was started to perform flash Joule heating treatment on the crystalline silicon solar cell powder, and the above flash Joule heating was repeated 4 times, for a total of 5 flash Joule heating cycles. Based on the intrinsic resistance characteristics, the crystalline silicon solar cell powder generated a violent Joule heating effect under the action of instantaneous high-power electric pulses, and the temperature instantly rose to 1800℃ within 500ms. The silver in the crystalline silicon solar cell powder underwent a vaporization transformation. The volatilized gaseous silver entered the -150℃ cold trap system and underwent directional condensation, transforming into silver powder, which was then recovered and reused. This achieved rapid and efficient recovery of silver from retired crystalline silicon photovoltaic modules, with a silver recovery rate of 80%.

[0060] Example 6 This embodiment recovers silver from decommissioned crystalline silicon photovoltaic modules using the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are mechanically disassembled to obtain the laminate. The laminate consists of tempered glass, EVA organic encapsulation material, crystalline silicon solar cell, EVA organic encapsulation material and TPT organic encapsulation material from top to bottom.

[0061] (2) The laminate is heat-treated at 550℃ for 60 minutes to completely remove the organic encapsulation material in the laminate by thermal decomposition, and the tempered glass and crystalline silicon solar cell are separated to obtain crystalline silicon solar cell.

[0062] (3) Use a Raymond mill (set its classifier speed to 200 rpm, control the roller pressure to 60% of the spring preload, and adjust the fan airflow to medium airflow at 55% of the damper opening) to grind and pulverize the crystalline silicon solar cell to 200 mesh, and then sieve out the 200 mesh crystalline silicon solar cell powder through mechanical screening.

[0063] (4) Place the crystalline silicon solar cell powder in a flash evaporation Joule heating device (e.g., Figure 2 In the reaction chamber shown, a vacuum was drawn until the system pressure reached 10. 1Pa. The temperature of the cold trap system is maintained at -200°C by using liquid nitrogen cooling. The applied voltage, heating time, and flash times of the flash Joule heating device are precisely controlled. The applied voltage is set to 100 V, and the heating time is set to 500 ms. The flash Joule heating device is started to perform flash Joule heating treatment on the crystalline silicon cell piece powder. The aforementioned flash Joule heating is repeated 4 times, and a total of 5 flash Joule heating treatments are performed. The crystalline silicon cell piece powder generates intense Joule heating effect under the action of the instantaneous high-power electric pulse based on the intrinsic resistance characteristics, and the temperature instantaneously rises to 1100°C within 500 ms. The silver in the crystalline silicon cell piece powder undergoes gasification transformation, and the volatilized gaseous silver enters the cold trap system at -200°C to undergo directional condensation and is converted into silver powder, which is then recycled and reused. The silver is quickly and efficiently recovered from the retired crystalline silicon photovoltaic module, and the silver recovery rate is 87%.

[0064] Example 7 In this example, silver is recovered from a retired crystalline silicon photovoltaic module by the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are disassembled by mechanical means to obtain a laminated piece. The laminated piece has, from top to bottom, a tempered glass, an EVA organic encapsulating material, a crystalline silicon cell piece, an EVA organic encapsulating material, and a TPT organic encapsulating material.

[0065] (2) The laminated piece is heat treated at 550°C for 60 min to completely pyrolyze and remove the organic encapsulating material in the laminated piece, and the tempered glass and the crystalline silicon cell piece are separated to obtain a crystalline silicon cell piece.

[0066] (3) The crystalline silicon cell piece is ground and crushed to 200 mesh using a Raymond mill (the speed of the classifier is set to 200 rpm, the roller pressure is controlled at 60% of the spring pre-tightening force, and the air door opening is adjusted to medium air volume). The 200-mesh crystalline silicon cell piece powder is screened out by mechanical screening.

[0067] (4) The crystalline silicon cell piece powder is placed in the reaction cavity of the flash Joule heating device (as shown in Figure 2 ), and the system pressure is vacuumed to 10 1Pa. The temperature of the cold trap system is maintained at -150°C by using liquid nitrogen cooling. The applied voltage, heating time, and flash times of the flash Joule heating device are precisely controlled. The applied voltage is set to 100 V, and the heating time is set to 1 s. The flash Joule heating device is started to perform flash Joule heating treatment on the crystalline silicon cell piece powder. The crystalline silicon cell piece powder is subjected to intense Joule heating effect under the action of a transient high-power electric pulse based on the intrinsic resistance characteristics, and the temperature instantaneously rises to 1100°C within 1 s. The silver in the crystalline silicon cell piece powder undergoes gasification transformation, and the volatilized gaseous silver enters the cold trap system at -150°C to undergo directional condensation and is converted into silver powder, which is then recycled and reused. The silver is quickly and efficiently recovered from the retired crystalline silicon photovoltaic module, and the silver recovery rate is 71%.

[0068] Example 8 In this example, silver is recovered from a retired crystalline silicon photovoltaic module by the following method: (1) The aluminum frame and junction box of the retired crystalline silicon photovoltaic module are disassembled by mechanical means to obtain a laminated piece. The laminated piece is composed of, from top to bottom, tempered glass, EVA organic packaging material, crystalline silicon cell piece, EVA organic packaging material, and TPT organic packaging material.

[0069] (2) The laminated piece is heat treated at 550°C for 60 min to completely pyrolyze and remove the organic packaging material in the laminated piece, and the tempered glass and crystalline silicon cell piece are separated to obtain a crystalline silicon cell piece.

[0070] (3) The crystalline silicon cell piece is ground and crushed to 200 mesh using a Raymond mill (the classifier speed of the Raymond mill is set to 200 rpm, the mill roller pressure is controlled at 60% of the spring pre-tightening force, and the air door opening degree is adjusted to 55% to control the air volume to medium air volume), and the 200-mesh crystalline silicon cell piece powder is screened out by mechanical screening.

[0071] (4) The crystalline silicon cell piece powder is placed in the reaction cavity of the flash Joule heating device (as shown in Figure 2 ), and the system pressure is vacuumed to 10 1Pa. The temperature of the cold trap system is maintained at-180 DEG C by using liquid nitrogen cooling. The applied voltage of the flash Joule heating device is set to 110 V, and the heating time is set to 700 ms. The flash Joule heating device is started to perform flash Joule heating treatment on the crystalline silicon cell piece powder, and the aforementioned flash Joule heating is repeated twice, for a total of three times. The crystalline silicon cell piece powder produces intense Joule heating effect under the action of the instantaneous high-power electric pulse based on the intrinsic resistance characteristics, and the temperature instantaneously rises to 1300 DEG C within 700 ms. The silver in the crystalline silicon cell piece powder is gasified and converted into volatile gas-phase silver. The volatile gas-phase silver enters the cold trap system at-180 DEG C and is directionally condensed to become silver powder, which is then recycled and reused. The silver is quickly and efficiently recycled from the decommissioned crystalline silicon photovoltaic module, and the silver recovery rate is 79%.

[0072] In summary, the crystalline silicon cell piece powder has an intrinsic resistance of 2-4 omega, so that the crystalline silicon cell piece powder produces intense Joule heating effect under the action of the instantaneous high-power electric pulse, and the temperature can be raised to a high level in a very short time, so that the silver in the crystalline silicon cell piece powder is gasified into gas phase. The gas-phase silver is sent to the cold trap system for directional condensation to obtain silver powder. The present application can gasify the silver in a very short time, effectively reducing the required time for recycling silver, improving the efficiency of recycling silver, and without using chemical reagents in the recycling process, improving the environmental friendliness of the recycling process, thereby realizing fast, efficient and green recycling of silver from decommissioned crystalline silicon photovoltaic modules with a high recovery rate.

[0073] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various modifications can be made to the form and details thereof without departing from the scope defined by the claims of the present application.

Claims

1. A method for fast and efficient recovery of silver from decommissioned crystalline silicon photovoltaic modules, characterized in that: The method comprises the following steps: (1) mechanically disassembling the retired crystalline silicon photovoltaic module to obtain a laminated piece; (2) performing heat treatment on the laminated piece obtained in the step (1) to remove the organic packaging material and obtain a crystalline silicon cell piece; (3) sequentially performing grinding and crushing and screening on the crystalline silicon cell piece obtained in the step (2) to obtain a crystalline silicon cell piece powder with uniform particle size; (4) under vacuum conditions, performing flash Joule heating on the crystalline silicon cell piece powder obtained in the step (3) to make silver in the crystalline silicon cell piece powder gasify and evaporate, then condensing the evaporated silver gas to obtain silver powder.

2. The method of claim 1, wherein: In the step (1), the aluminum frame and the junction box of the retired crystalline silicon photovoltaic module are mechanically disassembled.

3. The method of claim 1, wherein: In the step (2), the heat treatment is performed on the laminated piece in an argon atmosphere.

4. The method of claim 1, wherein: In the step (2), the heat treatment temperature is 550-650 DEG C, and the heat treatment time is 60 min.

5. The method of claim 1, wherein: In the step (3), the crystalline silicon cell piece is ground and crushed to 200 mesh particle size.

6. The method of claim 1, wherein: In the step (3), the mesh number of the screen used for screening is 200 mesh.

7. The method of claim 1, wherein: In step (4), the vacuum degree is 10. 1 ~10 5 Pa.

8. The method of claim 1, wherein: In the step (4), the number of flash Joule heating is 1-5 times, the voltage applied each time is the same and is 100-180 V, and the heating time each time is 500 ms-1 s.

9. The method of claim 1, wherein: The retired crystalline silicon photovoltaic module is a single-crystal silicon or polycrystalline silicon solar cell panel that has reached the service life or has been withdrawn from operation due to performance degradation.

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