Metal extraction apparatus and method for a photovoltaic cell

Abstract

The application provides a metal extraction device and method for a photovoltaic cell, which comprises an ultrasonic tank, an upper cover and an inner net rack, the upper cover is arranged above the ultrasonic tank and can close the ultrasonic tank, and the inner net rack is arranged inside the ultrasonic tank and is used for placing cell pieces; ultrasonic devices are arranged inside the bottom surface of the ultrasonic tank and inside the upper cover; a liquid inlet is arranged at the upper end of one side of the ultrasonic tank, a liquid outlet is arranged at the lower end of the opposite side, a tail gas outlet is arranged above the liquid outlet, control valves are arranged on the liquid inlet and the liquid outlet, and the extraction liquid can be automatically added into the ultrasonic tank according to the requirement; and the tail gas outlet is connected with a tail gas treatment device. The metal extraction device for the photovoltaic cell has the advantages of simple structure, convenient operation, metal extraction by using reagents and ultrasonic devices, fast and efficient metal extraction, no damage to the main structure of the cell silicon piece, and reduction of environmental pollution caused in the extraction process.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module recycling technology, and more particularly to a metal extraction device for photovoltaic cells. This invention also relates to a method for metal extraction from photovoltaic cells. Background Technology

[0002] Photovoltaic modules are composed of multiple individual solar cells connected in series and parallel and encapsulated, and are the core component of a solar power plant. The structure of a photovoltaic module includes encapsulating glass, EVA film, solar cells, and backsheet.

[0003] Crystalline silicon photovoltaic (PV) modules have a lifespan of approximately 25 years, and a large-scale wave of PV panel scrapping and recycling is imminent. According to relevant environmental policies, crystalline silicon PV modules require harmless treatment and resource recycling. Since silicon is the main component of crystalline silicon, its recycling value is significant if the entire module can be preserved. Currently, there are several methods, including heat treatment, organic solvent treatment, and laser cutting, which can completely separate the encapsulation glass and backsheet, thus preserving the complete structure of the PV cell.

[0004] Photovoltaic cells are primarily composed of silicon, coated with metals such as Al and Ag. Existing photovoltaic module recycling technologies involve complex metal extraction and recovery equipment, generating significant waste pollution during the process. This application proposes a method and equipment for reducing metal extraction in photovoltaic cells, primarily targeting cells that have been completely separated from their encapsulation glass and backsheet. It utilizes appropriate methods to extract metals without damaging the silicon wafer's main structure, while minimizing potential pollution during the extraction process. Summary of the Invention

[0005] The present invention aims to provide a metal extraction device for photovoltaic cells to overcome the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is: a metal extraction device for photovoltaic cells, comprising an ultrasonic tank, a top cover, and an inner mesh frame. The top cover is provided above the ultrasonic tank to seal it, and the inner mesh frame for placing the solar cells is provided inside the ultrasonic tank. Ultrasonic devices are provided inside the bottom surface of the ultrasonic tank and inside the top cover. An inlet is provided at the upper end of one side of the ultrasonic tank, and an outlet is provided at the lower end of the opposite side. Control valves are provided on both the inlet and outlet to automatically add extractant into the ultrasonic tank as needed. An exhaust gas outlet is provided above the outlet and is connected to an exhaust gas treatment device. The metal extraction equipment for photovoltaic cells described in this invention has a simple structure and is easy to operate. It employs an ultrasonic device simultaneously with the chemical extraction process, enabling rapid and efficient metal extraction. Furthermore, the ultrasonic device at the bottom of the ultrasonic tank works in conjunction with the ultrasonic device inside the upper cover to perform ultrasonic vibration treatment on the photovoltaic cells laid flat on the inner grid frame from both top and bottom dimensions, maximizing the utilization efficiency of ultrasound on the surface of the photovoltaic cells and further improving the extraction efficiency. The exhaust gas pollution generated during the extraction process is collected and treated through the exhaust gas outlet and exhaust gas treatment device, reducing environmental pollution caused by the extraction process.

[0007] Furthermore, in the aforementioned metal extraction equipment for photovoltaic cells, the ultrasonic tank is made of stainless steel, and the inner wall of the ultrasonic tank is provided with an anti-corrosion layer to reduce the corrosion of the equipment by the reagents. The anti-corrosion layer is a polytetrafluoroethylene layer.

[0008] Furthermore, in the aforementioned metal extraction equipment for photovoltaic cells, the top cover is made of stainless steel. The top cover has a handle, and the bottom surface has a protrusion that matches the opening at the top of the ultrasonic tank. When the top cover is closed, the protrusion can seal the opening at the top of the ultrasonic tank, reducing the diffusion of acidic exhaust gas. The side walls and bottom surface of the top cover are also provided with an anti-corrosion layer to reduce the corrosion of the equipment by the reagent. The anti-corrosion layer is a polytetrafluoroethylene layer.

[0009] Furthermore, in the aforementioned photovoltaic cell metal extraction equipment, the inner mesh frame is made of polytetrafluoroethylene (PTFE), which is a corrosion-resistant material that extends the service life of the inner mesh frame. The bottom surface of the inner mesh frame is provided with raised feet, and there is a gap between it and the bottom surface of the ultrasonic tank to avoid direct contact between the photovoltaic cell and the ultrasonic tank.

[0010] Furthermore, in the aforementioned metal extraction equipment for photovoltaic cells, the inner mesh frame is an open-top mesh frame with multiple evenly distributed waist-shaped through holes on its side walls and circular through holes on its bottom surface. The upper end of the circular through holes has rounded corners. The waist-shaped and circular through holes allow the extraction liquid to flow quickly without accumulation, increasing the reaction between the reagent and the solar cells. In addition, the waist-shaped through holes can also be used for hook operation of the hoisting equipment.

[0011] Furthermore, in the aforementioned photovoltaic cell metal extraction equipment, a heating device is also provided inside the bottom surface of the ultrasonic tank. The heating device is used to set the temperature during metal extraction, thereby improving extraction efficiency.

[0012] This invention also provides a method for metal extraction from photovoltaic cells, comprising the following steps:

[0013] S1. Open the ultrasonic tank inlet and exhaust outlet, and close the outlet.

[0014] S2. Add hydrochloric acid dilution to the ultrasonic tank through the dosing device, control the pH in the range of 2-6, and ensure that the solution depth does not exceed 2 / 3 of the tank height and covers the height of the battery cells. Then close the inlet of the ultrasonic tank.

[0015] S3. Place the photovoltaic cells that have undergone separation pretreatment flat in the inner grid frame. Multiple layers can be stacked, with a maximum of 20 layers.

[0016] S4. Immerse the inner mesh frame containing the battery cells in the ultrasonic tank, and start the ultrasonic device. The frequency of the ultrasonic device is 20-90HZ.

[0017] S5. After sonication for 3-120 minutes, open the outlet and collect the extract from this step, naming it extract A.

[0018] S6. Open the inlet and clean water enters the ultrasonic tank through the inlet to rinse the inner wall of the ultrasonic tank, photovoltaic cells and inner mesh frame. After cleaning, open the outlet and the cleaning solution flows into the extract A.

[0019] S7. Add concentrated nitric acid solution into the ultrasonic tank through the dosing device. The pH should be controlled within the range of 2-6. The solution depth should not exceed 2 / 3 of the tank height and should cover the height of the battery cells. Then close the inlet of the ultrasonic tank.

[0020] S8. Immerse the battery cells in the inner grid frame in concentrated nitric acid solution and start the ultrasonic device. The frequency of the ultrasonic device is 20-90HZ.

[0021] S9. After sonication for 3-120 minutes, open the outlet and collect the extract from this step, naming it extract B.

[0022] S10. Open the inlet and clean water enters the ultrasonic tank through the inlet to rinse the inner wall of the ultrasonic tank, photovoltaic cells and inner mesh frame. After cleaning, open the outlet and the cleaning solution flows into the extract B.

[0023] S11. Add NaOH solution to extract A until Al ions in the solution are completely precipitated. After filtration, washing and drying, the recovered product Al(OH)3 is obtained.

[0024] S12. Add a saturated NaCl solution and a mixed solution of hydrochloric acid and nitric acid to extract B. The ratio of hydrochloric acid to nitric acid in the mixed solution is 3:1. Continue until Ag ions in the solution are completely precipitated. After filtration, washing and drying, AgCl is obtained as the recovered product.

[0025] Furthermore, in the above-mentioned method for extracting metals from photovoltaic cells, in step S2, the heating device is turned on to control the liquid temperature in the ultrasonic tank to 20-60℃.

[0026] Furthermore, in the above-mentioned method for extracting metals from photovoltaic cells, in step S7, the heating device is turned on to control the liquid temperature in the ultrasonic tank to 20-60℃.

[0027] Furthermore, in the aforementioned method for metal extraction from photovoltaic cells, the exhaust gas or acid mist generated during the metal extraction process is discharged through the exhaust gas outlet and collected and treated uniformly by the exhaust gas treatment device.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The metal extraction equipment for photovoltaic cells described in the present invention has a simple structure and is easy to operate. It employs an ultrasonic device simultaneously with the chemical extraction process, enabling rapid and efficient metal extraction without damaging the main structure of the silicon wafer. Furthermore, the ultrasonic device at the bottom of the ultrasonic tank works in conjunction with the ultrasonic device inside the upper cover to perform ultrasonic vibration treatment on the photovoltaic cells laid flat on the inner grid frame from both top and bottom dimensions, maximizing the utilization efficiency of ultrasound on the photovoltaic cell surface and improving extraction efficiency. Finally, the exhaust gas pollution generated during the extraction process is collected and treated through the exhaust gas outlet and exhaust gas treatment device, reducing environmental pollution caused during the extraction process. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the metal extraction device for photovoltaic cells of the present invention. Figure 1 ;

[0031] Figure 2 This is a schematic diagram of the metal extraction device for photovoltaic cells of the present invention. Figure 2 ;

[0032] Figure 3 This is a schematic diagram of the internal grid structure of the metal extraction device for photovoltaic cells according to the present invention;

[0033] In the diagram: 1. Ultrasonic tank; 11. Liquid inlet; 12. Liquid outlet; 13. Exhaust gas outlet;

[0034] 2. Top cover; 21. Handle; 22. Boss;

[0035] 3. Inner mesh frame; 31. Elevated feet; 32. Waist-shaped through hole; 33. Circular through hole. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] like Figure 1-3 As shown, a metal extraction device for photovoltaic cells includes an ultrasonic tank 1, a top cover 2, and an inner mesh frame 3. The top cover 2 is provided above the ultrasonic tank 1 to seal it, and the inner mesh frame 3 is provided inside the ultrasonic tank 1 to hold the solar cells. Ultrasonic devices (not shown) are provided inside the bottom surface of the ultrasonic tank 1 and inside the top cover 2. An inlet 11 is provided at the upper end of one side of the ultrasonic tank 1, and an outlet 12 is provided at the lower end of the opposite side. Control valves are provided on both the inlet 11 and the outlet 12. Chemicals or cleaning water can be added to the inlet, and the control valve can be automatically controlled to add extraction liquid into the ultrasonic tank as needed. An exhaust gas outlet 13 is provided above the outlet 12 and is connected to an exhaust gas treatment device. A heating device (not shown) is also provided inside the bottom surface of the ultrasonic tank 1 to set the temperature during metal extraction and improve extraction efficiency.

[0039] The metal extraction equipment for photovoltaic cells described in this invention has a simple structure and is easy to operate. It employs an ultrasonic device simultaneously with the chemical extraction process, enabling rapid and efficient metal extraction. Furthermore, the ultrasonic device at the bottom of the ultrasonic tank 1 works in conjunction with the ultrasonic device inside the upper cover 2 to perform ultrasonic vibration treatment on the photovoltaic cells laid flat on the inner mesh frame 3 from both top and bottom dimensions, maximizing the utilization efficiency of ultrasound on the surface of the photovoltaic cells and further improving the extraction efficiency. The exhaust gas pollution generated during the extraction process is collected and treated through the exhaust gas outlet 13 and the exhaust gas treatment device, reducing environmental pollution caused by the extraction process.

[0040] In the above structure, the ultrasonic tank 1 is made of stainless steel, specifically 316 stainless steel. The inner wall of the ultrasonic tank 1 is provided with an anti-corrosion layer to reduce the corrosion of the equipment by the agent. The anti-corrosion layer is a polytetrafluoroethylene layer.

[0041] Among them, such as Figure 1-2 As shown, the upper cover 2 is made of stainless steel, specifically 316 stainless steel. The top of the upper cover 2 is provided with a handle 21, and the bottom surface is provided with a boss 22 that matches the top opening of the ultrasonic tank 1. When the upper cover 2 closes the ultrasonic tank 3, the boss 22 can seal the top opening of the ultrasonic tank 1, reducing the diffusion of acidic exhaust gas. The side walls and bottom surface of the upper cover 2 are also provided with an anti-corrosion layer to reduce the corrosion of the equipment by the agent. The anti-corrosion layer is a polytetrafluoroethylene layer.

[0042] Among them, such as Figure 3 As shown, the inner mesh frame 3 is made of polytetrafluoroethylene (PTFE), which is a corrosion-resistant material that extends the service life of the inner mesh frame 3. The bottom surface of the inner mesh frame 3 is provided with raised feet 31, which creates a gap between it and the bottom surface of the ultrasonic tank 1 to avoid direct contact between the photovoltaic cells and the ultrasonic tank 1.

[0043] In addition, such as Figure 3 As shown, the inner mesh frame 3 is an open-top mesh frame with multiple evenly distributed waist-shaped through holes 32 on its side walls and circular through holes 33 on its bottom surface. The upper end of the circular through holes 33 has rounded corners. The waist-shaped through holes 32 and the circular through holes 33 allow the extract to flow quickly without accumulating liquid, increasing the reaction between the reagent and the battery cells. In addition, the waist-shaped through holes 32 can also be used for hook operation of hoisting equipment to hoist the inner mesh frame, facilitating the loading and unloading of the inner mesh frame.

[0044] The present invention also provides a metal extraction method using the above-mentioned photovoltaic cell metal extraction equipment, comprising the following steps:

[0045] S1. Open the inlet 11 and outlet 13 of the ultrasonic tank 1, and close the outlet.

[0046] S2. Add hydrochloric acid diluent to ultrasonic tank 1 through the dosing device. The pH value is 2. The solution depth should not exceed 2 / 3 of the tank height and should cover the height of the battery cells. Turn on the heating device and control the liquid temperature in ultrasonic tank 1 to 20-60℃. Then close the ultrasonic tank inlet 11.

[0047] S3. Place the photovoltaic cells that have undergone separation pretreatment flat in the inner grid frame 3. Multiple layers can be stacked, with a maximum of 20 layers.

[0048] S4. Immerse the inner mesh frame 3 containing the battery cells in the ultrasonic tank 1, and start the ultrasonic device. The frequency of the ultrasonic device is 20-90HZ.

[0049] S5. After sonication for 3-120 minutes, open outlet 12 and collect the extract from this step, naming it extract A.

[0050] S6. Open the inlet 11 and clean water enters the ultrasonic tank 1 from the inlet 11 to rinse the inner wall of the ultrasonic tank 1, the photovoltaic cell, and the inner mesh frame 3. After cleaning, open the outlet 12 and the cleaning solution flows into the extract A.

[0051] S7. Then, add concentrated nitric acid solution to the ultrasonic tank 1 through the dosing device. The pH value is 2. The solution depth should not exceed 2 / 3 of the tank height and should cover the height of the battery cells. Turn on the heating device and control the liquid temperature in the ultrasonic tank to 20-60℃. Then close the ultrasonic tank inlet 11.

[0052] S8. The battery cells in the inner mesh frame 3 are immersed in concentrated nitric acid solution. The ultrasonic device is activated, and the frequency of the ultrasonic device is 20-90HZ.

[0053] S9. After sonication for 3-120 minutes, open outlet 12 and collect the extract from this step, naming it extract B.

[0054] S10. Open the liquid inlet 11 and clean water enters the ultrasonic tank 1 from the liquid inlet 11 to rinse the inner wall of the ultrasonic tank 1, photovoltaic cells, and inner mesh frame 3. After cleaning, open the liquid outlet 12 and the cleaning liquid flows into the extract liquid B.

[0055] S11. Add NaOH solution to extract A until Al ions in the solution are completely precipitated. After filtration, washing and drying, the recovered product Al(OH)3 is obtained. The aluminum metal in the photovoltaic panel dissolves in hydrochloric acid solution. The pH of the hydrochloric acid solution is controlled at around 2, which can dissolve aluminum well and the extraction rate can reach 91%.

[0056] S12. Add a saturated NaCl solution and a mixed solution of hydrochloric acid and nitric acid to extract B. The ratio of hydrochloric acid to nitric acid in the mixed solution is 3:1. Continue adding the solution until Ag ions are completely precipitated. After filtration, washing, and drying, AgCl is obtained as the recovered product. The metallic silver in the photovoltaic panel is not easily dissolved in pure hydrochloric acid. However, when nitric acid is added, the dissolution and extraction rate increases significantly. The pH of the hydrochloric acid and nitric acid mixture is around 2, and the extraction rate of metallic silver can reach 87%.

[0057] S13. During the metal extraction process, the exhaust gas or acid mist generated is discharged through the exhaust gas outlet 13 and collected and treated uniformly by the exhaust gas treatment device.

[0058] Example 2

[0059] like Figure 1-3As shown, a metal extraction device for photovoltaic cells includes an ultrasonic tank 1, a top cover 2, and an inner mesh frame 3. The top cover 2 is provided above the ultrasonic tank 1 to seal it, and the inner mesh frame 3 is provided inside the ultrasonic tank 1 to hold the solar cells. Ultrasonic devices (not shown) are provided inside the bottom surface of the ultrasonic tank 1 and inside the top cover 2. An inlet 11 is provided at the upper end of one side of the ultrasonic tank 1, and an outlet 12 is provided at the lower end of the opposite side. Control valves are provided on both the inlet 11 and the outlet 12. Chemicals or cleaning water can be added to the inlet, and the control valve can be automatically controlled to add extraction liquid into the ultrasonic tank as needed. An exhaust gas outlet 13 is provided above the outlet 12 and is connected to an exhaust gas treatment device. A heating device (not shown) is also provided inside the bottom surface of the ultrasonic tank 1 to set the temperature during metal extraction and improve extraction efficiency.

[0060] The metal extraction equipment for photovoltaic cells described in this invention has a simple structure and is easy to operate. It employs an ultrasonic device simultaneously with the chemical extraction process, enabling rapid and efficient metal extraction. Furthermore, the ultrasonic device at the bottom of the ultrasonic tank 1 works in conjunction with the ultrasonic device inside the upper cover 2 to perform ultrasonic vibration treatment on the photovoltaic cells laid flat on the inner mesh frame 3 from both top and bottom dimensions, maximizing the utilization efficiency of ultrasound on the surface of the photovoltaic cells and further improving the extraction efficiency. The exhaust gas pollution generated during the extraction process is collected and treated through the exhaust gas outlet 13 and the exhaust gas treatment device, reducing environmental pollution caused by the extraction process.

[0061] In the above structure, the ultrasonic tank 1 is made of stainless steel, specifically 316 stainless steel. The inner wall of the ultrasonic tank 1 is provided with an anti-corrosion layer to reduce the corrosion of the equipment by the agent. The anti-corrosion layer is a polytetrafluoroethylene layer.

[0062] Among them, such as Figure 1-2 As shown, the upper cover 2 is made of stainless steel, specifically 316 stainless steel. The top of the upper cover 2 is provided with a handle 21, and the bottom surface is provided with a boss 22 that matches the top opening of the ultrasonic tank 1. When the upper cover 2 closes the ultrasonic tank 3, the boss 22 can seal the top opening of the ultrasonic tank 1, reducing the diffusion of acidic exhaust gas. The side walls and bottom surface of the upper cover 2 are also provided with an anti-corrosion layer to reduce the corrosion of the equipment by the agent. The anti-corrosion layer is a polytetrafluoroethylene layer.

[0063] Among them, such as Figure 3 As shown, the inner mesh frame 3 is made of polytetrafluoroethylene (PTFE), which is a corrosion-resistant material that extends the service life of the inner mesh frame 3. The bottom surface of the inner mesh frame 3 is provided with raised feet 31, which creates a gap between it and the bottom surface of the ultrasonic tank 1 to avoid direct contact between the photovoltaic cells and the ultrasonic tank 1.

[0064] In addition, such as Figure 3As shown, the inner mesh frame 3 is an open-top mesh frame with multiple evenly distributed waist-shaped through holes 32 on its side walls and circular through holes 33 on its bottom surface. The upper end of the circular through holes 33 has rounded corners. The waist-shaped through holes 32 and the circular through holes 33 allow the extract to flow quickly without accumulating liquid, increasing the reaction between the reagent and the battery cells. In addition, the waist-shaped through holes 32 can also be used for hook operation of hoisting equipment to hoist the inner mesh frame, facilitating the loading and unloading of the inner mesh frame.

[0065] The present invention also provides a metal extraction method using the above-mentioned photovoltaic cell metal extraction equipment, comprising the following steps:

[0066] S1. Open the inlet 11 and outlet 13 of the ultrasonic tank 1, and close the outlet.

[0067] S2. Add hydrochloric acid diluent to ultrasonic tank 1 through the dosing device. The pH value is 4. The solution depth should not exceed 2 / 3 of the tank height and should cover the height of the battery cells. Turn on the heating device and control the liquid temperature in ultrasonic tank 1 to 20-60℃. Then close the ultrasonic tank inlet 11.

[0068] S3. Place the photovoltaic cells that have undergone separation pretreatment flat in the inner grid frame 3. Multiple layers can be stacked, with a maximum of 20 layers.

[0069] S4. Immerse the inner mesh frame 3 containing the battery cells in the ultrasonic tank 1, and start the ultrasonic device. The frequency of the ultrasonic device is 20-90HZ.

[0070] S5. After sonication for 3-120 minutes, open outlet 12 and collect the extract from this step, naming it extract A.

[0071] S6. Open the inlet 11 and clean water enters the ultrasonic tank 1 from the inlet 11 to rinse the inner wall of the ultrasonic tank 1, the photovoltaic cell, and the inner mesh frame 3. After cleaning, open the outlet 12 and the cleaning solution flows into the extract A.

[0072] S7. Then, add concentrated nitric acid solution to the ultrasonic tank 1 through the dosing device. The pH value is 6. The solution depth should not exceed 2 / 3 of the tank height and should cover the height of the battery cells. Turn on the heating device and control the liquid temperature in the ultrasonic tank to 20-60℃. Then close the ultrasonic tank inlet 11.

[0073] S8. The battery cells in the inner mesh frame 3 are immersed in concentrated nitric acid solution. The ultrasonic device is activated, and the frequency of the ultrasonic device is 20-90HZ.

[0074] S9. After sonication for 3-120 minutes, open outlet 12 and collect the extract from this step, naming it extract B.

[0075] S10. Open the liquid inlet 11 and clean water enters the ultrasonic tank 1 from the liquid inlet 11 to rinse the inner wall of the ultrasonic tank 1, photovoltaic cells, and inner mesh frame 3. After cleaning, open the liquid outlet 12 and the cleaning liquid flows into the extract liquid B.

[0076] S11. Add NaOH solution to extract A until Al ions in the solution are completely precipitated. After filtration, washing and drying, the recovered product Al(OH)3 is obtained. The aluminum metal in the photovoltaic panel dissolves in hydrochloric acid solution. The pH of the hydrochloric acid solution is controlled at about 4, which can dissolve aluminum well and the extraction rate can reach 75%.

[0077] S12. Add a saturated NaCl solution and a mixed solution of hydrochloric acid and nitric acid to extract B. The ratio of hydrochloric acid to nitric acid in the mixed solution is 3:1. Continue adding the solution until Ag ions are completely precipitated. After filtration, washing, and drying, AgCl is obtained as the recovered product. The metallic silver in the photovoltaic panel is not easily dissolved in pure hydrochloric acid. However, when nitric acid is added, the dissolution and extraction rate increases significantly. The pH of the hydrochloric acid and nitric acid mixture is around 6, and the extraction rate of metallic silver can reach 21%.

[0078] S13. During the metal extraction process, the exhaust gas or acid mist generated is discharged through the exhaust gas outlet 13 and collected and treated uniformly by the exhaust gas treatment device.

[0079] The metal extraction method for photovoltaic cells described in this invention is easy to operate, has high extraction efficiency, and generates little pollution.

[0080] 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 invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0081] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A metal extraction device for photovoltaic cells, characterized in that: The device includes an ultrasonic tank (1), a top cover (2), and an inner mesh frame (3). The top cover (2) is provided above the ultrasonic tank (1) to seal the ultrasonic tank (1). The inner mesh frame (3) for placing battery cells is provided inside the ultrasonic tank (1). An ultrasonic device is provided inside the bottom surface of the ultrasonic tank (1) and inside the top cover (2). An inlet (11) is provided at the upper end of one side of the ultrasonic tank (1), and an outlet (12) is provided at the lower end of the opposite side. A control valve is provided on both the inlet (11) and the outlet (12). An exhaust gas outlet (13) is provided above the outlet (12), and the exhaust gas outlet (13) is connected to an exhaust gas treatment device. A method for metal extraction from photovoltaic cells includes the following steps: S1. Open the inlet (11) and outlet (13) of the ultrasonic tank (1), and close the outlet (12). S2. Add hydrochloric acid dilution to the ultrasonic tank (1) through the dosing device. The pH is controlled within the range of 2-6. The solution depth should not exceed 2 / 3 of the tank height and should be above the height of the battery cell. Then close the ultrasonic tank inlet (11). S3. Place the photovoltaic cells that have undergone separation pretreatment flat in the inner grid frame (3). They can be stacked in multiple layers, with a maximum of 20 layers. S4. Immerse the inner mesh frame (3) containing the battery cells in the ultrasonic tank (1), and start the ultrasonic device. The frequency of the ultrasonic device is 20-90HZ. S5. After sonication for 3-120 minutes, open the outlet (12) and collect the extract from this step, naming it extract A. S6. Open the inlet (11) and clean water enters the ultrasonic tank (1) from the inlet (11) to rinse the inner wall of the ultrasonic tank (1), photovoltaic cells, and inner mesh frame (3). After cleaning, open the outlet (12) and the cleaning liquid flows into the extract A. S7. Add concentrated nitric acid solution to the ultrasonic tank (1) through the dosing device. The pH is controlled within the range of 2-6. The solution depth should not exceed 2 / 3 of the tank height and should be above the height of the battery cell. Then close the ultrasonic tank inlet (11). S8. The battery cells in the inner grid (3) are immersed in concentrated nitric acid solution. The ultrasonic device is started, and the frequency of the ultrasonic device is 20-90HZ. S9. After sonication for 3-120 minutes, open the outlet (12) and collect the extract from this step, naming it extract B. S10. Open the inlet (11) and clean water enters the ultrasonic tank (1) from the inlet (11) to rinse the inner wall of the ultrasonic tank (1), photovoltaic cells, and inner mesh frame (3). After cleaning, open the outlet (12) and the cleaning liquid flows into the extract B. S11. Add NaOH solution to extract A until Al ions in the solution are completely precipitated. After filtration, washing and drying, the recovered product Al(OH)3 is obtained. S12. Add a saturated NaCl solution and a mixed solution of hydrochloric acid and nitric acid to extract B. The ratio of hydrochloric acid to nitric acid in the mixed solution is 3:

1. Continue until Ag ions in the solution are completely precipitated. After filtration, washing and drying, AgCl is obtained as the recovered product.

2. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: The ultrasonic tank (1) is made of stainless steel, and the inner wall of the ultrasonic tank (1) is provided with an anti-corrosion layer, which is a polytetrafluoroethylene layer.

3. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: The top cover (2) is made of stainless steel. The top of the top cover (2) is provided with a handle (21) and the bottom is provided with a boss (22) that matches the opening at the top of the ultrasonic tank (1). The side wall and bottom of the top cover (2) are also provided with an anti-corrosion layer, which is a polytetrafluoroethylene layer.

4. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: The inner mesh frame (3) is made of polytetrafluoroethylene, and the bottom surface of the inner mesh frame (3) is provided with raised feet (31).

5. The metal extraction equipment for photovoltaic cells according to claim 4, characterized in that: The inner mesh frame (3) is a mesh frame with an open top. Its side wall is evenly provided with multiple waist-shaped through holes (32), and its bottom surface is provided with a circular through hole (33). The upper surface of the circular through hole (33) is provided with rounded corners.

6. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: The ultrasonic tank (1) is also equipped with a heating device inside the bottom surface.

7. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: In step S2, the heating device is turned on to control the temperature of the liquid in the ultrasonic tank to 20-60℃.

8. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: In step S7, the heating device is turned on to control the temperature of the liquid in the ultrasonic tank to 20-60℃.

9. The metal extraction equipment for photovoltaic cells according to claim 1, characterized in that: During the metal extraction process, the generated exhaust gas or acid mist is discharged through the exhaust gas outlet (13) and collected and treated uniformly by the exhaust gas treatment device.

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