A method and device for chemically stripping silver from waste crystalline silicon photovoltaic cells

Abstract

The application relates to the technical field of metal recovery, and discloses a chemical silver extraction method and device for waste crystalline silicon photovoltaic cell pieces, which comprises the following steps: S1, removing the cell piece laminated piece, cutting and separating the metal frame and the glass and crushing; S2, putting the crushed pieces into an acid leaching device and adding a nitric acid-hydrofluoric acid mixed leaching agent; S3, filtering after reaction to obtain a silver-containing filtrate and a silicon residue; and S4, adding saturated NaCl solution into the silver-containing filtrate to generate white AgCl precipitate, filtering after standing and collecting the AgCl precipitate. The chemical silver extraction method for the waste crystalline silicon photovoltaic cell pieces realizes synchronous leaching of silver and aluminum, etching of silicon nitride and release of silver ions through one-step room-temperature synergistic leaching of a nitric acid-hydrofluoric acid compound system, and efficiently dissolves the aluminum paste layer in a short time, protects the silicon matrix, and realizes synchronous leaching of silver and aluminum and protection of the silicon matrix in a short time. In combination with a short-process silver chlorination and zinc powder replacement process, high-purity elemental silver and reusable silicon material are directly obtained, and the core problems of high energy consumption, low purity and heavy pollution in the traditional process are solved.

Description

Technical Field

[0001] This invention relates to the field of metal recycling technology, and in particular to a method and apparatus for chemically extracting silver from waste crystalline silicon photovoltaic cells. Background Technology

[0002] Crystalline silicon photovoltaic cells contain valuable silver, and the efficient recovery of silver from retired cells is a key requirement for achieving resource recycling and economic viability. Currently, mainstream recovery methods include high-temperature pyrolysis to remove organic matter and then enriching the silver, and wet leaching with nitric acid or mixed acids to dissolve the metal before recovery.

[0003] Currently, existing technologies have certain shortcomings in practical applications: at the method level, pyrometallurgical processes consume extremely high energy, while hydrometallurgical processes, although carried out at room temperature, have long reaction times and often require step-by-step processing of aluminum and silver, resulting in lengthy processes. At the same time, the leaching process is prone to excessive corrosion of the silicon substrate due to improper control of hydrofluoric acid concentration, resulting in low silicon recovery rate and decreased purity. Incomplete separation in the silver precipitation process will also affect the purity of silver.

[0004] Furthermore, at the equipment level, especially in the core equipment of wet acid leaching, after the acid leaching unit completes the reaction, the filter cylinder containing solid residue needs to be lifted out of the acid leaching tank as a whole, and then the filter cylinder needs to be opened manually to remove the residue. This process not only requires workers to be in close contact with residual acid and wet residue with corrosive liquid attached, which poses a serious safety risk, but also the manual opening and closing of the filter cylinder bottom cover is inefficient, and incomplete residue removal can easily leave residual acid, resulting in a significant increase in the water consumption for subsequent rinsing. Moreover, the frequent lifting, opening, and slag removal operations cause long production line interruption times, affecting production efficiency. Summary of the Invention

[0005] The technical problem to be solved by this invention is that the existing technology has drawbacks such as high energy consumption, lengthy process and insufficient recycling purity. To address this, we propose a chemical silver extraction method and apparatus for waste crystalline silicon photovoltaic cells.

[0006] To achieve the above objectives, this application adopts the following technical solution: a method for chemically extracting silver from waste crystalline silicon photovoltaic cells, comprising the following steps:

[0007] S1: Remove the battery cell laminate, cut and separate the metal frame and glass, and break them;

[0008] S2: The fragments are put into the acid leaching device, and a nitric acid-hydrofluoric acid mixed leaching agent is added to dissolve the aluminum paste layer and etch the silicon nitride antireflection layer.

[0009] S3: After the reaction, filter to obtain silver-containing filtrate and silicon residue. Rinse the silicon with deionized water to remove surface acid and impurities, and dry to obtain high-purity silicon.

[0010] S4: Add saturated NaCl solution to the silver-containing filtrate to form a white AgCl precipitate. After standing, filter and collect the AgCl precipitate.

[0011] S5: Mix AgCl precipitate with zinc powder, add dilute sulfuric acid, stir to displace, then filter and wash to obtain spongy elemental silver;

[0012] S6: After silver precipitation, the waste liquid is neutralized to neutral with lime, and after heavy metals are precipitated, it is discharged in compliance with standards. The washed silicon material is reused as a metallurgical raw material after purity testing.

[0013] Preferably, in step S2, the solid-liquid ratio of the fragments to the nitric acid-hydrofluoric acid mixed leaching agent is 1:5, and the concentration of HNO3 is 10-15% and the concentration of HF is 3-5%.

[0014] Preferably, in step S5, AgCl precipitate and zinc powder are mixed at a mass ratio of 1:0.3, and the mass fraction of dilute sulfuric acid is 10%.

[0015] This application also includes an embodiment, specifically a chemical silver extraction device for waste crystalline silicon photovoltaic cells, including an acid leaching tank and a support set at the upper end of the acid leaching tank. A filter cylinder is set in the acid leaching tank, and a lifting frame is set at the upper end of the filter cylinder. A first drive source for lifting the lifting frame is set at the upper end of the support, and a second drive source for driving the filter cylinder to rotate is set on the lifting frame.

[0016] The filter cartridge has openings evenly distributed on its circumferential sidewalls. A flip frame is symmetrically rotated at both ends of one of the openings. Arc-shaped filter plates are provided on the inner side of the flip frame and the inner side of the other openings. The flip frame is connected to the filter cartridge via a snap-fit ​​assembly. The snap-fit ​​assembly includes a snap block movably disposed on the inner side of the end of the flip frame. A second elastic element is provided between the snap block and the inner wall of the end of the flip frame. A slot corresponding to the snap block is provided on the inner end of the opening. The snap block is trapezoidal, and one end of it engages with the slot.

[0017] The filter cartridge end is provided with an unlocking component, which includes a drive arm movably disposed inside the filter cartridge end and corresponding to the slot. One end of the drive arm extends to the inside of the slot and engages with the inclined surface of the slot block. The other end sidewall is provided with a first force-bearing block extending to the outside of the filter cartridge. The upper end of the bracket is provided with a discharge arm corresponding to the first force-bearing block.

[0018] Preferably, the support is provided with a receiving mechanism for receiving silicon residue. The receiving mechanism includes a fixed frame disposed on one side of the support and used to support the receiving device. The end of the fixed frame is provided with a second rack plate that is movably connected to the side of the support. A gear that meshes with the second rack plate is rotatably disposed on the inner side of the support. The end of the lifting frame is provided with a first rack plate that extends to the inner side of the support and corresponds to one end of the gear.

[0019] Preferably, a torsion spring is provided at the rotatable part of the flipping frame and the opening end, and the torsion spring torsional deformation occurs when the flipping frame flips.

[0020] Preferably, the end of the drive arm away from the block is provided with a third elastic element, configured such that the third elastic element contracts when the drive arm moves toward the block.

[0021] Preferably, the acid leaching tank is provided with an acid circulation mechanism, which includes a rotating shaft rotatably disposed at the end of the inner cavity of the acid leaching tank. A second force-bearing block is provided on the side wall of one end of the rotating shaft, and a toggle block corresponding to the second force-bearing block is provided on one side of the first force-bearing block. A rotating plate is provided at the other end of the rotating shaft, and an arc-shaped piston rod is provided on one side of the rotating plate. A spray pipe is provided at one end of the inner cavity of the acid leaching tank, and a piston cylinder corresponding to the piston rod is provided at the end of the spray pipe. One end of the piston cylinder is connected to the spray pipe, and one end of the piston rod is movably connected to the inside of the piston cylinder. A first elastic element is sleeved on one end of the piston rod. A suction port is provided at the bottom of the spray pipe, and a spray port corresponding to the side of the filter cartridge is provided on one side of the upper end of the spray pipe. Both the suction port and the spray port are provided with one-way valves.

[0022] Preferably, the first elastic element is a spring.

[0023] Preferably, the lifting frame is provided with a through groove corresponding to the unloading arm.

[0024] The technical effects and advantages of this invention are as follows:

[0025] In this invention, a one-step synergistic leaching process using a nitric acid-hydrofluoric acid composite system at room temperature simultaneously and efficiently dissolves the aluminum paste layer, etches silicon nitride, and releases silver ions. This achieves simultaneous silver and aluminum leaching and silicon substrate protection in a short time. Combined with a short-process silver chloride precipitation-zinc powder replacement process, high-purity elemental silver and reusable silicon material are directly obtained. Moreover, the leaching waste liquid is used entirely in a closed loop for the silver precipitation process, and the terminal wastewater is neutralized and discharged in compliance with standards. This solves the core problems of high energy consumption, low purity, and heavy pollution associated with traditional processes, achieving cost reduction, efficiency improvement, and green low-carbon goals for the resource recycling of retired photovoltaic modules.

[0026] In this invention, the flipping frame, along with the snap-fit ​​and unlocking components, can automatically open when the filter cylinder rises to a certain level after the filter cylinder is finished. Combined with the pre-positioned receiving mechanism at the bottom of the filter cylinder, the residue can be automatically discharged and collected. When the filter cylinder descends, the receiving mechanism automatically moves away, which not only improves production efficiency but also ensures high safety.

[0027] In this invention, the acid circulation mechanism can accelerate the flow of acid from the bottom of the acid leaching tank into the filter cartridge by rotating the first force block, thereby accelerating the flow and renewal of acid, reducing the problem of poor acid flow caused by filter plate blockage, and improving the reaction effect. Attached Figure Description

[0028] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0029] Figure 1 This is a schematic diagram of the method flow structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the acid leaching apparatus of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of the acid leaching device support, acid leaching tank, and filter cartridge in the disassembled state.

[0032] Figure 4 This is a schematic diagram of the structure of the receiving mechanism and filter cartridge of the present invention in their combined state;

[0033] Figure 5 This is a structural diagram of the lifting frame and filter cartridge of the present invention in their disassembled state;

[0034] Figure 6 This is a structural diagram of the flip frame and filter cartridge of the present invention in their disassembled state;

[0035] Figure 7 This is a schematic diagram of the structure of the flip frame end and the opening end of the present invention in a disassembled state;

[0036] Figure 8 This is a schematic cross-sectional view of the present invention with the flip frame and the opening end in a snap-fit ​​state.

[0037] Figure 9 This is a structural diagram of the drive arm and filter cartridge end in a disassembled state according to the present invention;

[0038] Figure 10 This is a schematic diagram of the internal structure of the acid leaching tank of the present invention.

[0039] Legend: 1. Support; 2. Acid leaching tank; 3. Screw; 4. First drive motor; 5. Unloading arm; 6. Filter cartridge; 7. Linear guide rail; 8. First rack plate; 9. Fixing frame; 10. Filter plate; 11. Second rack plate; 12. Gear; 13. Second drive motor; 14. Sprocket; 15. Chain; 16. Opening; 17. Tilting frame; 18. First force-bearing block; 19. Actuating block; 20. Drive arm; 21. Locking block; 22. Torsion spring; 23. First elastic element; 24. Second elastic element; 25. Slot; 26. Piston rod; 27. Guide pin; 28. Third elastic element; 29. ​​Tilting shaft; 30. Second force-bearing block; 31. Tilting plate; 32. Piston cylinder; 33. Nozzle; 34. Nozzle; 35. Suction port; 36. Lifting frame. Detailed Implementation

[0040] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0041] Reference Figure 1 The image shows a method for chemically extracting silver from waste crystalline silicon photovoltaic cells, comprising the following steps:

[0042] Step 1: Manually remove the EVA / backsheet of the battery cells. Use a glass cutter and a battery cell crusher to cut and separate the metal frame and glass, and then crush them, preferably to a size of 5×5cm. 2 Fragments;

[0043] Step 2: Put the fragments into the acid leaching device, add nitric acid-hydrofluoric acid mixed leaching agent at a solid-liquid ratio of 1:5, wherein the HNO3 concentration is 10-15% and the HF concentration is 3-5%, soak and rotate at room temperature of 25±5℃ for 60-90 minutes to dissolve the aluminum paste layer and etch the silicon nitride antireflection layer. During this process, the exhaust gas is passed into the acid mist absorption tower for treatment.

[0044] Step 3: After the reaction, filter to obtain silver-containing filtrate and silicon residue. Rinse the silicon with deionized water 3 times to remove surface acid and impurities, and dry to obtain high-purity silicon.

[0045] Step 4: Slowly add saturated NaCl solution to the silver-containing filtrate to form a white AgCl precipitate, and control the Cl concentration. ⁻ Add 10% excess, let stand for 30 minutes, filter, and collect the AgCl precipitate. This step can be achieved by a precipitation reaction tank and a plate and frame filter press.

[0046] Step 5: Mix AgCl precipitate and zinc powder at a mass ratio of 1:0.3, add 10% dilute sulfuric acid, stir and displace for 30 minutes, the reaction formula is: 2AgCl+Zn→2Ag+ZnCl2, then filter and wash to obtain spongy elemental silver;

[0047] Step 6: The waste liquid after silvering is neutralized to neutral with lime, and heavy metals are precipitated before being discharged in compliance with standards. The washed silicon material is tested for purity by a silicon material composition analyzer and then reused as a metallurgical raw material.

[0048] This method dissolves silver / aluminum with nitric acid and etches silicon nitride with hydrofluoric acid. It operates at room temperature and is energy-saving. Moreover, it extracts silver through a three-step process of acid leaching, silver precipitation, and displacement, avoiding high-energy-consuming steps such as traditional roasting. Furthermore, all acid leaching waste liquid is used for silver precipitation and is discharged in compliance with standards after neutralization, thus solving pollution problems. The silicon material after rinsing has a high silicon content and can be directly used in metallurgy or silicon smelting.

[0049] like Figures 2-10 As shown, this application also includes an embodiment, specifically a chemical silver extraction device for waste crystalline silicon photovoltaic cells, applied to the above-mentioned chemical silver extraction method for waste crystalline silicon photovoltaic cells, specifically the acid leaching device in step 2;

[0050] Specifically, such as Figures 2-8 As shown, the device includes an acid leaching tank 2 and a support 1 mounted on the upper end of the acid leaching tank 2. A filter cylinder 6 is disposed in the acid leaching tank 2. Openings 16 are evenly distributed on the circumferential sidewalls of the filter cylinder 6. A flipping frame 17 is symmetrically and rotatably mounted on both ends of one of the openings 16. Arc-shaped filter plates 10 are disposed on the inner side of the flipping frame 17 and the inner side of the remaining openings 16. A lifting frame 36 is disposed on the upper end of the filter cylinder 6. A screw 3 is rotatably mounted on the upper end of the support 1. A first drive motor 4 for driving the screw 3 to rotate is disposed on the top of the support 1. The upper end of the lifting frame 36 is threadedly engaged with the screw 3, so that the rotation of the screw 3 and the lifting frame 36 can drive the filter cylinder 6 to rise and fall. Rotating shafts that rotate with the lower side of the lifting frame 36 are disposed at both ends of the filter cylinder 6. A pair of sprockets 14 are rotatably arranged on one side of the filter cylinder 6, and a chain 15 is meshed on both sprockets 14. The shaft at one end of the filter cylinder 6 is fixedly arranged with the middle of the lower sprocket 14. A second drive motor 13 for driving the upper sprocket 14 to rotate is arranged on the outside of the lifting frame 36. In order to facilitate loading and unloading, the flipping frame 17 and the filter cylinder 6 are connected by a snap-fit ​​assembly. As a preferred embodiment, the snap-fit ​​assembly includes a snap block 21 movably arranged on the inner side of the end of the flipping frame 17. A second elastic element 24 is arranged between the snap block 21 and the inner wall of the end of the flipping frame 17. The second elastic element 24 is preferably a spring. A slot 25 corresponding to the snap block 21 is arranged on the inner end of the opening 16. The snap block 21 is trapezoidal and one end of it is snapped into the slot 25.

[0051] Furthermore, such as Figure 2 , Figures 6-9As shown, in order to achieve automatic opening of the flip frame 17 during lifting, an unlocking component is provided at the end of the filter cylinder 6. In a preferred embodiment, the unlocking component includes a drive arm 20 movably disposed inside the end of the filter cylinder 6 and corresponding to the slot 25. One end of the drive arm 20 extends into the inside of the slot 25 and engages with the inclined surface of one end of the locking block 21. The lower end of the drive arm 20 can completely squeeze out the end of the locking block 21 located inside the slot 25. The other end of the drive arm 20 is provided with a first force block 18 extending to the outside of the filter cylinder 6. The upper end of the bracket 1 is provided with a discharge arm 5 corresponding to the first force block 18. The lifting frame 36 is provided with a through groove corresponding to the discharge arm 5. When the filter cylinder 6 rises, the lower end of the discharge arm 5 can pass through... The drive arm 20 contacts the first force-bearing block 18 through the through groove. To facilitate the reset of the drive arm 20, a guide pin 27 corresponding to one end of the drive arm 20 is provided on the inner side of the end of the filter cylinder 6. The cross section of the guide pin 27 is "T" shaped. The end of the drive arm 20 away from the locking block 21 is movably connected to the guide pin 27. A third elastic element 28 is sleeved on one end of the guide pin 27. The third elastic element 28 is preferably a spring. It is configured such that when the drive arm 20 moves towards the locking block 21, the third elastic element 28 contracts. In order to increase the stability of the flipping frame 17 and improve the opening efficiency of the flipping frame 17, a torsion spring 22 is provided at the rotation point of the flipping frame 17 and the opening 16. When the flipping frame 17 flips, the torsion spring 22 torsional deformation occurs.

[0052] like Figures 2-3 As shown, in order to move the receiving device directly below the filter cartridge 6 before the flip frame 17 is opened, a receiving mechanism for receiving silicon residue is provided on the support 1. The receiving mechanism includes a fixing frame 9 located on one side of the support 1 to support the receiving device. A second rack plate 11 is movably connected to the side of the support 1 at the end of the fixing frame 9. To increase the stability of the second rack plate 11 and the fixing frame 9, a linear guide rail 7 is provided on the side of the support 1 to support the second rack plate 11. The linear guide rail 7 is movable and guided. The inner side of the bracket 1 is rotatably provided with a gear 12 that meshes with the top of the second rack plate 11. The end of the lifting frame 36 is provided with a first rack plate 8 that extends to the inner side of the bracket 1 and corresponds to one end of the gear 12. The configuration is as follows: when the filter cylinder 6 is higher than the fixed frame 9, the first rack plate 8 meshes with the gear 12. When the fixed frame 9 is directly below the filter cylinder 6, the first rack plate 8 separates from the gear 12. After the first rack plate 8 separates from the gear 12, the unloading arm 5 contacts the first force block 18.

[0053] In addition, such as Figure 6 , Figures 9-10As shown, to enhance the flow of acid in the pickling tank 2, an acid circulation mechanism is provided in the pickling tank 2. This mechanism includes a rotating shaft 29 rotatably mounted at the end of the inner cavity of the pickling tank 2. A second force-bearing block 30 is provided on the side wall of one end of the rotating shaft 29. A actuating block 19 corresponding to the second force-bearing block 30 is provided on one side of the first force-bearing block 18. The configuration is such that when the filter cartridge 6 rotates within the inner cavity of the pickling tank 2, the actuating block 19 can contact the second force-bearing block 30. A rotating plate 31 is provided at the other end of the rotating shaft 29. An arc-shaped piston rod 26 is provided on one side of the rotating plate 31. A spray pipe 33 is provided at one end of the inner cavity of the pickling tank 2. A piston cylinder 32 corresponding to the piston rod 26 is provided at the end of the spray pipe 33. One end of the piston cylinder 32 is connected to the spray pipe 33. The piston rod 26 is movably connected to the inside of the piston cylinder 32. A first elastic element 23 is sleeved on one end of the piston rod 26. The first elastic element 23 is preferably a spring. The spring can be reset after the piston rod 26 is displaced in the direction of the piston cylinder 32. The bottom of the nozzle 33 is provided with multiple suction ports 35 for sucking in acid. The upper side of the nozzle 33 is provided with a nozzle 34 corresponding to the side of the filter cartridge 6. Both the suction port 35 and the nozzle 34 are provided with one-way valves. The one-way valve on the suction port 35 only allows the acid in the cavity of the acid leaching tank 2 to enter the nozzle 33 from the suction port 35. The one-way valve on the nozzle 34 only allows the acid in the nozzle 33 to be sprayed out from the nozzle 34. This realizes the transfer of the acid at the bottom of the acid leaching tank 2 to the inside of the filter cartridge 6, improving the fluidity of the acid.

[0054] The specific working principle of the chemical silver extraction device for waste crystalline silicon photovoltaic cells is as follows: In the initial state, the filter cartridge 6 is located at the upper end of the acid leaching tank 2, with the opening 16 corresponding to the flipping frame 17 facing upwards or to the side. Broken photovoltaic cell fragments are added into the inner cavity of the filter cartridge 6 through the corresponding opening 16 at the flipping frame 17. Then, the flipping frame 17 is flipped and closed, causing one end of the locking block 21 to be displaced under pressure, compressing the second elastic element 24. When the locking block 21 matches the locking groove 25, the second elastic element 24 resets, and one end of the locking block 21 is inserted into the inner cavity of the locking groove 25. Then, the first drive motor 4 is controlled to drive the screw 3 to rotate. The screw 3, through the lifting frame 36, drives the filter cartridge 6 to move downwards. A nitric acid-hydrofluoric acid mixed leaching agent is added to the acid leaching tank 2, and the filter cartridge 6 enters... In the leaching agent, the second drive motor 13 is controlled to slowly rotate the filter cartridge 6 through the cooperation of the sprocket 14 and the chain 15. During rotation, the actuating block 19 on one side of the first force block 18 will contact the second force block 30, thereby driving the flip shaft 29, the flip plate 31, and the piston rod 26 to rotate by a certain degree through the second force block 30. Then, the first elastic element 23 contracts, and the piston rod 26 squeezes the piston cylinder 32 and the inner cavity of the nozzle 33, which can squeeze the acid in the inner cavity of the nozzle 33 out of the nozzle 34. Then, the squeezed acid is blown onto the filter plate 10 on the surface of the filter cartridge 6 and enters the inner cavity of the filter cartridge 6 through the filter plate, thereby accelerating the flow of the acid. A receiving device, such as a receiving trough or other receiving device, is placed or fixed on the fixing frame 9 in advance. After completion, the flip shaft 29, the flip plate 10, and the filter cartridge 6 will rotate. The frame 17 rotates until it stops directly below the filter cylinder 6. Then, the filter cylinder 6 rises again through the rotation of the screw 3. The first rack plate 8 rises with the lifting frame 36. When the filter cylinder 6 is higher than the fixed frame 9, the first rack plate 8 begins to mesh with the gear 12. The gear 12 then drives the fixed frame 9 to move horizontally through the second rack plate 11. When the fixed frame 9 is directly below the filter cylinder 6, the first rack plate 8 separates from the gear 12, and the fixed frame 9 stops. Subsequently, the unloading arm 5 passes through the through slot on the lifting frame 36 and contacts the first force block 18, thereby pushing the first force block 18 and the drive arm 20 to move as a whole. The third elastic element 28 retracts, and one end of the drive arm 20 moves by pressing the clamping block 21 through the inclined surface. Then, one end of the clamping block 21 moves out of the clamp. The tank 25 is disengaged. Under the combined action of the weight of the flipping frame 17, the filter plate 10, and the residue, as well as the restoring force of the torsion spring 22, the flipping frame 17 flips upward and opens. Then, the residue inside the filter cylinder 6 falls into the receiving device at the top of the fixed frame 9. Then, the acid in the acid leaching tank 2 is discharged. The filter cylinder 6 and the acid leaching tank 2 are cleaned as needed. In subsequent use, the screw 3 first drives the filter cylinder 6 to move down a certain distance, so that the unloading arm 5 separates from the first force block 18. The second drive motor 13 is controlled to drive the filter cylinder 6 to rotate a certain amplitude, so that the opening 16 corresponding to the flipping frame 17 is located on the side or facing upward, which is convenient for feeding. Then, the flipping frame 17 is closed, and the filter cylinder 6 is controlled to move down. The fixed frame 9 is moved away, and the filter cylinder 6 enters the inner cavity of the acid leaching tank 2 again. This cycle is repeated.

[0055] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for chemically extracting silver from waste crystalline silicon photovoltaic cells, characterized in that, Includes the following steps: S1: Remove the battery cell laminate, cut and separate the metal frame and glass, and break them; S2: The fragments are put into the acid leaching device, and a nitric acid-hydrofluoric acid mixed leaching agent is added to dissolve the aluminum paste layer and etch the silicon nitride antireflection layer. S3: After the reaction, filter to obtain silver-containing filtrate and silicon residue. Rinse the silicon with deionized water to remove surface acid and impurities, and dry to obtain high-purity silicon. S4: Add saturated NaCl solution to the silver-containing filtrate to form a white AgCl precipitate. After standing, filter and collect the AgCl precipitate. S5: Mix AgCl precipitate with zinc powder, add dilute sulfuric acid, stir to displace, then filter and wash to obtain spongy elemental silver; S6: The waste liquid after silver precipitation is neutralized to neutral with lime, and after heavy metal precipitation, it is discharged in compliance with standards. The silicon material after rinsing is recycled as a metallurgical raw material after purity testing. The acid leaching device in step S2 includes an acid leaching tank and a support set at the upper end of the acid leaching tank. A filter cylinder is set in the acid leaching tank, and a lifting frame is set at the upper end of the filter cylinder. A first drive source for lifting the lifting frame is set at the upper end of the support, and a second drive source for driving the filter cylinder to rotate is set on the lifting frame. The filter cartridge has openings evenly distributed on its circumferential sidewalls. A flip frame is symmetrically rotated at both ends of one of the openings. Arc-shaped filter plates are provided on the inner side of the flip frame and the inner side of the other openings. The flip frame is connected to the filter cartridge via a snap-fit ​​assembly. The snap-fit ​​assembly includes a snap block movably disposed on the inner side of the end of the flip frame. A second elastic element is provided between the snap block and the inner wall of the end of the flip frame. A slot corresponding to the snap block is provided on the inner end of the opening. The snap block is trapezoidal, and one end of it engages with the slot. The filter cartridge end is provided with an unlocking component, which includes a drive arm movably disposed inside the filter cartridge end and corresponding to the slot. One end of the drive arm extends to the inside of the slot and engages with the inclined surface of the slot block. The other end sidewall is provided with a first force-bearing block extending to the outside of the filter cartridge. The upper end of the bracket is provided with a discharge arm corresponding to the first force-bearing block.

2. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, In step S2, the solid-liquid ratio of the fragments to the nitric acid-hydrofluoric acid mixed leaching agent is 1:5, and the concentration of HNO3 is 10-15% and the concentration of HF is 3-5%.

3. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, In step S5, AgCl precipitate and zinc powder are mixed at a mass ratio of 1:0.3, and the mass fraction of dilute sulfuric acid is 10%.

4. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, The support is provided with a receiving mechanism for collecting silicon residue. The receiving mechanism includes a fixed frame located on one side of the support and used to support the receiving device. The end of the fixed frame is provided with a second rack plate that is movably connected to the side of the support. A gear that meshes with the second rack plate is rotatably provided on the inner side of the support. The end of the lifting frame is provided with a first rack plate that extends to the inner side of the support and corresponds to one end of the gear.

5. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, A torsion spring is provided at the rotation point of the flipping frame and the opening end. When the flipping frame flips, the torsion spring is torsional and deformed.

6. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, The end of the drive arm away from the block is provided with a third elastic element, configured such that the third elastic element contracts when the drive arm moves toward the block.

7. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, The acid leaching tank is equipped with an acid circulation mechanism, which includes a rotating shaft rotatably disposed at the end of the inner cavity of the acid leaching tank. A second force-bearing block is disposed on the side wall of one end of the rotating shaft, and a toggle block corresponding to the second force-bearing block is disposed on one side of the first force-bearing block. A rotating plate is disposed at the other end of the rotating shaft, and an arc-shaped piston rod is disposed on one side of the rotating plate. A spray pipe is disposed at one end of the inner cavity of the acid leaching tank, and a piston cylinder corresponding to the piston rod is disposed at the end of the spray pipe. One end of the piston cylinder is connected to the spray pipe, and one end of the piston rod is movably connected to the inside of the piston cylinder. A first elastic element is sleeved on one end of the piston rod. A suction port is disposed at the bottom of the spray pipe, and a spray port corresponding to the side of the filter cartridge is disposed on one side of the upper end of the spray pipe. Both the suction port and the spray port are provided with one-way valves.

8. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 7, characterized in that, The first elastic element is a spring.

9. The method for chemically extracting silver from waste crystalline silicon photovoltaic cells according to claim 1, characterized in that, The lifting frame is provided with a through groove corresponding to the unloading arm.

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