A method and system for physical recycling of waste silicon photovoltaic laminates

Abstract

The present application relates to a kind of physical recycling method and system of waste silicon photovoltaic laminate, comprising the following steps: (1) liquid nitrogen soaking: waste silicon photovoltaic laminate A is placed in liquid nitrogen and soaked, obtain waste silicon photovoltaic laminate B;(2) mechanical removal: waste silicon photovoltaic laminate B is separated and respectively collected to obtain glass panel, back plate and silicon chip;(3) mechanical friction: silicon chip is placed in room temperature condition and is warmed, then by mechanical friction, electrode metal powder, wire and silicon plate are recycled.The present application effectively enriches electrode metal powder, wire, silicon plate, glass panel, back plate and other materials, which can be used for subsequent recycling and reuse.The method of the present application does not use organic solvent, does not exist wet process and heating process, and has the advantages of green and energy saving.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solid waste recycling, and particularly relates to a physical recycling method and system for waste silicon photovoltaic laminates. BACKGROUND

[0002] Monocrystalline / polycrystalline silicon photovoltaic panels are the most widely used solar cells at present. The structure of a silicon photovoltaic panel is mainly composed of a glass panel, a silicon chip, and a PET / TPT / metal back panel, wherein the silicon chip is usually provided with a silver coating and a tin-coated copper wire, and the glass panel, the chip, and the back panel are laminated together by using ethylene-vinyl acetate copolymer (EVA) as an adhesive layer. The waste silicon photovoltaic laminates contain a large amount of glass, silicon, plastic, and metal resources, and if not properly disposed of, they can easily cause waste accumulation and environmental pollution problems. Therefore, recycling waste silicon photovoltaic laminates is not only a demand for secondary resource utilization, but also a necessary process for environmental protection.

[0003] There are currently some public reports on recycling waste solar cells: Chinese patent application CN115769384A discloses a method for processing waste solar cells, which involves heating solar cell modules with resin back panels and sealing resin layers in a thermal decomposition furnace to melt and oxidize the resin components in the solar cell modules. Similarly, Chinese patent application CN108823411A discloses a method for recycling metals and energy gases from waste solar panels, which involves separating and recycling organic components from waste solar panels through vacuum pyrolysis treatment, and then using vacuum metallurgical methods to gasify metal components and recover individual metals by temperature gradient fractional condensation based on the boiling point differences of different metals under vacuum conditions. This method has the characteristics of efficient separation of metals, but the vacuum gasification-condensation separation method requires high equipment and operation requirements, and the highest temperature for metal gasification needs to reach not less than 1400℃, which requires a large amount of energy to maintain high vacuum at this temperature, and the value of the recovered metal products is relatively low, which still needs further processing for subsequent production and utilization. With the progress of science and technology, some improved recycling technologies have emerged, such as Chinese patent application CN115591540A, which discloses a method for recycling and preparing a hydrolysis hydrogen production catalyst using waste solar panels, which uses heating to 350-450℃ to remove EVA and PET packaging. However, during the heating and decomposition process, metal elements are easily lost, resulting in a loss of recycling value, and the evaporation and diffusion of metals into the environment also pose a risk of pollution.

[0004] There are also solvent soaking recovery methods, Chinese patent application CN116535734A, the paper A Novel Combined Technology of Rich Reactive Oxygen Species and Ultrasound for the Decapsulation of Waste Cu(InGa)Se-2 Solar Cells uses reactive oxygen combined with ultrasound to achieve the effect of removing ethylene-vinyl acetate copolymer (EVA), but the wet process of soaking inevitably causes pollution problems of wastewater and organic solvents.

[0005] There are also mechanical separation methods, Chinese patent application CN115816313A provides a device for separating cover glass in retired solar cells, which uses micro-particle medium jetting to separate chips, which cannot completely recover chip materials, and the operation time is long, and industrialization is difficult.

[0006] In order to recover complete silicon chips, glass panels, back panels and other materials as much as possible during the recycling process, reduce environmental risks, and increase recycling value, it is urgent to develop an efficient physical recycling method and system for waste silicon photovoltaic laminates. SUMMARY

[0007] The purpose of the present application is to overcome the above technical deficiencies, provide a physical recycling method and system for waste silicon photovoltaic laminates, and solve the technical problem that the waste silicon photovoltaic laminates cannot be effectively separated during recycling.

[0008] To achieve the above technical purpose, the technical solution provided by the present application is:

[0009] In a first aspect, the present application provides a physical recycling method for waste silicon photovoltaic laminates, comprising the following steps:

[0010] (1) Liquid nitrogen soaking: placing the waste silicon photovoltaic laminates A in liquid nitrogen for soaking to obtain waste silicon photovoltaic laminates B;

[0011] (2) Mechanical removal: separating the waste silicon photovoltaic laminates B and collecting the glass panel, back panel and silicon chip respectively;

[0012] (3) Mechanical friction: placing the silicon chip in room temperature conditions, then recovering the electrode metal powder, wire and silicon plate by mechanical friction.

[0013] Preferably, in step (1), the liquid nitrogen soaking time is 100-150s.

[0014] Preferably, in step (2), the waste silicon photovoltaic laminate B is separated in a single pass within 30 seconds; if the single pass cannot be completed within 30 seconds, return to step (1) to repeat the liquid nitrogen soaking and separation.

[0015] Preferably, the humidity of the environment in steps (1) and (2) is controlled to be less than 50%.

[0016] Preferably, in step (3), the silicon chip is placed at room temperature for more than 300 seconds.

[0017] In a second aspect, the present application provides a physical recycling system for waste silicon photovoltaic laminates, comprising a liquid nitrogen soaking device, a mechanical stripping device and a mechanical friction device; wherein,

[0018] The liquid nitrogen soaking device is used for liquid nitrogen soaking of the waste silicon photovoltaic laminate A.

[0019] The mechanical stripping device comprises an operating table, a movable knife plate support, a knife plate and a negative pressure fixer, the negative pressure fixer is located above the operating table and is used for fixing the waste silicon photovoltaic laminate B; the knife plate is installed on the movable knife plate support and is parallel to the upper surface of the operating table, the movable knife plate support is installed on the operating table and can drive the knife plate to move parallel to the upper surface of the operating table, during the movement, the cutting edge of the knife plate always faces the adhesive layer in the waste silicon photovoltaic laminate B, and the waste silicon photovoltaic laminate B is separated to obtain a glass panel, a back plate and a silicon chip.

[0020] The mechanical friction device comprises a plurality of friction plates for stripping the silicon chip to obtain electrode metal powder, wires and silicon plates.

[0021] Preferably, the liquid nitrogen soaking device comprises a liquid nitrogen container and a steel structure platform with a size smaller than the liquid nitrogen container, and the liquid nitrogen level in the liquid nitrogen container is greater than 20 mm.

[0022] Preferably, a first sliding rail is arranged on the side of the operating table, and the axis of the first sliding rail is parallel to the upper surface of the operating table; the movable knife plate support is connected with a first roller, and the first roller is located in the first sliding rail and can move back and forth along the first sliding rail.

[0023] Preferably, a second sliding rail is arranged on the movable knife plate support, and the knife plate is connected with a second roller, and the second roller is located in the second sliding rail and can move up and down along the second sliding rail.

[0024] The friction plates are arranged side by side, and the friction plates are provided with holes or gaps; the mechanical friction device further comprises a feeding roller and a discharging roller for conveying the silicon chip, and a screen for screening the electrode metal powder and the wires, the feeding roller and the discharging roller are arranged at both ends of the friction plates respectively, and the screen is arranged below the friction plates.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] The present application comprises three basic links of liquid nitrogen soaking, mechanical stripping and mechanical rubbing. The liquid nitrogen soaking makes the adhesive layer in the waste silicon photovoltaic laminated piece shrink and form a gap, and reduces the mechanical strength and viscosity, which is beneficial to the mechanical stripping, so as to separate the glass panel, the back panel and the silicon chip. Then the mechanical rubbing is used to separate and recycle the electrode metal powder, the wire and the silicon plate. The present application effectively enriches the electrode metal powder, the wire, the silicon plate, the glass panel, the back panel and other materials, which can be used for subsequent recycling and reuse. The method of the present application does not use any organic solvent, and does not have a wet process and a heating process, so it has the advantages of being green and energy-saving. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a process flow chart of the physical recycling method of the waste silicon photovoltaic laminated piece of the present application;

[0028] Figure 2 is a structural schematic diagram of the waste silicon photovoltaic laminated piece after the liquid nitrogen soaking of the present application;

[0029] Figure 3 is a structural schematic diagram of the mechanical stripping device of the present application, (a) is a front view, and (b) is a side view;

[0030] Figure 4 is a structural schematic diagram of the mechanical rubbing device of the present application.

[0031] 1-waste silicon photovoltaic laminated piece, 101-glass panel, 102-first adhesive layer, 103-silicon chip, 104-second adhesive layer, 105-back panel, 106-silicon plate;

[0032] 2-mechanical stripping device, 201-operation table, 202-mobile knife plate support, 203-knife plate, 204-negative pressure fixer, 205-first sliding rail, 206-first roller, 207-second sliding rail, 208-second roller;

[0033] 3-mechanical rubbing device, 301-rubbing sheet, 302-feeding roller, 303-discharging roller, 304-sieve net. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0035] In the existing waste silicon photovoltaic laminate recycling process, the fire method technology is easy to cause material loss and waste gas pollution; the wet method recycling is easy to cause waste water and solvent pollution; the conventional mechanical technology cannot effectively separate the complete silicon chip, glass and back plate components; in view of the above defects, the present application provides a physical recycling method and system for waste silicon photovoltaic laminates, which does not need chemical process, does not exist pollutant emission, and can quickly, effectively and completely recycle the intact laminate components, the recycling product has high value, and the recycling process is simple.

[0036] Referring to Figure 1 The present application provides a physical recycling method for waste silicon photovoltaic laminates, comprising the following steps:

[0037] (1) Liquid nitrogen soaking: placing the waste silicon photovoltaic laminate A in liquid nitrogen for soaking to obtain waste silicon photovoltaic laminate B;

[0038] (2) Mechanical stripping: separating the waste silicon photovoltaic laminate B and collecting the glass panel, back plate and silicon chip respectively;

[0039] (3) Mechanical friction: placing the silicon chip in room temperature condition for warming up, and then recycling electrode metal powder, wire and silicon plate through mechanical friction.

[0040] Preferably, in step (1), the liquid nitrogen soaking time is 100-150s.

[0041] Preferably, in step (2), the waste silicon photovoltaic laminate B is separated for single time within 30s; if the single separation cannot be completed within 30s, then returning to step (1) to repeat the liquid nitrogen soaking and then separating.

[0042] Preferably, the environmental humidity of step (1) and step (2) is controlled to be lower than 50%.

[0043] Preferably, in step (3), the silicon chip is placed in room temperature condition for warming up for more than 300s. The warming up function is to restore the fracture stress performance of the silicon plate and metal material to the initial value, so that they do not break during the friction process, and the purpose is to recycle the complete silicon plate.

[0044] Referring to Figure 2 The waste photovoltaic laminate to be treated in the present application comes from the dense laminated structure after the frame and junction box are removed, and specifically comprises a glass panel 101, a first adhesive layer 102, a silicon chip 103, a second adhesive layer 104 and a back plate 105 which are sequentially stacked.

[0045] Referring to Figures 3 to 4 The present application provides a physical recycling system for waste silicon photovoltaic laminates, comprising a liquid nitrogen soaking device, a mechanical stripping device 2 and a mechanical friction device 3.

[0046] It can be understood that the waste silicon photovoltaic laminates can be horizontally placed, vertically placed or obliquely placed for processing. Hereinafter, the waste silicon photovoltaic laminates are horizontally placed on the mechanical stripping device 2 for processing, which is only for more clearly describing the present application, but not for limiting the present application.

[0047] The liquid nitrogen soaking device is used for soaking the waste silicon photovoltaic laminates 1 in liquid nitrogen.

[0048] As a preferred embodiment, the liquid nitrogen soaking device comprises a liquid nitrogen container and a steel structure platform with a size smaller than that of the liquid nitrogen container. The size of the liquid nitrogen container is larger than that of the steel structure platform, so that the steel structure platform is put into the liquid nitrogen container. In use, the waste silicon photovoltaic laminates 1 are placed on the steel structure platform, and then the steel structure platform is put into or taken out of the liquid nitrogen container, so as to facilitate the waste silicon photovoltaic laminates 1 to be put into the liquid nitrogen container for soaking and taken out.

[0049] In order to ensure that the waste silicon photovoltaic laminates 1 can be fully soaked, the liquid nitrogen level in the liquid nitrogen container is greater than 20 mm. If it is lower, it needs to be supplemented in real time.

[0050] More preferably, the size of the steel structure platform is 300mm*300mm.

[0051] Referring to Figure 3 , the mechanical stripping device 2 comprises an operation table 201, a movable knife plate support 202, a knife plate 203 and a negative pressure fixer 204. The negative pressure fixer 204 is located above the operation table 201 and is used for fixing the waste silicon photovoltaic laminates 1 after liquid nitrogen soaking. The knife plate 203 is installed on the movable knife plate support 202 and is parallel to the upper surface of the operation table 201. The movable knife plate support 202 is installed on the operation table 201 and can drive the knife plate 203 to move in parallel on the upper surface of the operation table 201.

[0052] Referring to Figure 2 , during the movement of the knife plate 203, the cutting edge of the knife plate 203 always faces the first adhesive layer 102 or the second adhesive layer 104 in the waste silicon photovoltaic laminates 1 after liquid nitrogen soaking, so as to separate the waste silicon photovoltaic laminates 1 after liquid nitrogen soaking to obtain the glass panel 101, the back plate 105 and the silicon chip 103.

[0053] In a preferred embodiment, a first slide rail 205 is provided on the side of the operating table 201, and the axis of the first slide rail 205 is parallel to the upper surface of the operating table 201; a movable blade support 202 is connected to a first roller 206, the first roller 206 is located in the first slide rail 205 and can move back and forth along the first slide rail 205, thereby driving the movable blade support 202 and the blade 203 to move, and then the blade 203 completes the cutting of the first adhesive layer 102 or the second adhesive layer 104, so that the waste silicon photovoltaic laminate 1 after being soaked in liquid nitrogen is separated.

[0054] In a preferred embodiment, the movable blade holder 202 is provided with a second slide rail 207, and the blade 203 is connected to a second roller 208. The second roller 208 is located in the second slide rail 207 and can move up and down along the second slide rail 207, thereby driving the blade to move up and down, so that the blade 203 can be adjusted up and down along the second slide rail 207.

[0055] Optionally, the upper surface of the operating table 201 of the mechanical removal device 2 adopts a roller structure to facilitate material transportation.

[0056] Optionally, the rollers in the mechanical removal device 2 can be driven by a motor to move on the slide rail; the upper slide rail and rollers work together to adjust the height of the blade; the lower slide rail moves horizontally to separate the layers.

[0057] During the removal process, the negative pressure retainer 204 holds the glass panel 101 of the waste silicon photovoltaic laminate 1, which has been soaked in liquid nitrogen, in place. A worker then operates the blade 203 to place its tip (i.e., the cutting edge) on the surface. Figure 2 Positioned directly opposite the first adhesive layer 102, the blade 203 is pushed to separate the glass panel 101 from the silicon chip 103. Then, the negative pressure retainer 204 holds the back plate 105 of the laminate in place. The worker then positions the tip of the blade 203 directly opposite the second adhesive layer 104 and pushes the blade 203 to separate the back plate 105 from the silicon chip 103, thereby collecting the glass panel 101, silicon chip 103, and back plate 105 respectively.

[0058] The liquid nitrogen immersion time is 100-150 seconds, and the time from removing the waste silicon photovoltaic laminate from the liquid nitrogen to completing the mechanical removal should not exceed 30 seconds. If the mechanical removal cannot be completed within 30 seconds, the waste silicon photovoltaic laminate needs to be immersed in liquid nitrogen again before the second removal. The liquid nitrogen immersion and mechanical removal processes must be completed in the same space, and the humidity of this space must be controlled to be below 50%.

[0059] See Figure 4 The mechanical friction device 3 includes several friction plates 301, which are used to strip the silicon chip 103 to obtain electrode metal powder, wires and silicon plate 106.

[0060] As a preferred embodiment, the friction sheets 301 are arranged side by side; the mechanical friction device 3 further comprises a feeding roller 302 and a discharging roller 303 for conveying the silicon chip, and a screen 304 for screening the electrode metal powder and the wire, the feeding roller 302 and the discharging roller 303 are arranged at both ends of the friction sheet 301 respectively, and the screen 304 is arranged below the friction sheet 301.

[0061] As a preferred embodiment, the friction sheet 301 is provided with holes or arranged in a gap mode, so as to facilitate the electrode metal powder and the wire to fall onto the screen 304 for screening.

[0062] Before entering the mechanical friction device, the silicon chip needs to be placed in a normal temperature condition for re-warming for more than 300s; the re-warmed silicon chip 103 is brought into the friction sheet 301 area by the feeding roller 302 driven by the motor, the friction sheet 301 vibrates back and forth along the running direction of the silicon chip (i.e. vibrates left and right in the structure shown in the figure), the electrodes on the surface of the silicon chip 103 are rubbed off and fall onto the screen 304, at this time, the powder (containing electrode metal and part of the plastic) falls below the screen 304, and the wire is intercepted by the screen 304. Figure 4

[0063] The technical principle of separating the glass panel 101, the silicon chip 103 and the back plate 105 by liquid nitrogen soaking and mechanical stripping in the application is that: the main component of the first adhesive layer 102 or the second adhesive layer 104 is EVA, the EVA material weakens and the mechanical strength decreases under the condition of lower than-50℃, and the volume shrinkage degree is much larger than that of the tempered glass and the back plate, forming the notch structure shown in the figure, so that the cutting edge of the knife plate 203 enters its structure, and the unpacking is realized by mechanical stripping. Figure 2

[0064] The main control conditions and action mechanisms in the application include:

[0065] (1) If the liquid nitrogen soaking time is too short or the stripping time is too long, the side surface of the waste silicon photovoltaic laminated piece cannot form the notch structure as shown in the figure, and the adhesive effect is too strong in the process of knife plate stripping, so that the stripping cannot be smoothly realized, and the glass / metal / silicon plate structure is damaged; the soaking time is increased or the stripping time is shortened, and there is no relative influence; Figure 2

[0066] (2) The environmental humidity affects the coupling and adhesion effect, and too high humidity leads to the failure of the stripping process, so the application is preferably carried out in an environment below room temperature, and the humidity is controlled below 50%.

[0067] ​​​(3) Compared with the treatment mode of liquid nitrogen spraying, the liquid nitrogen soaking treatment is more conducive to reducing the loss of liquid nitrogen, and the soaking treatment is conducive to thorough cooling, and the efficiency is higher than that of the liquid nitrogen spraying cooling mode, and the liquid nitrogen soaking makes the surface glass rapidly cooled, the bonding surface of the glass and the EVA glue is subjected to a force greater than the liquid nitrogen contact surface, so that stress concentration occurs as soon as possible, and the glass is broken, which is conducive to reducing the motor working resistance in the peeling process.

[0068] (4) The waste silicon photovoltaic laminated piece is broken and separated as a whole, and there is a particle size limit, the present application adopts the peeling and mechanical friction mode, which is conducive to completely separating the glass, metal and silicon plate, and the liquid nitrogen soaking time is 100-150s, which prevents the silicon plate from being excessively cooled to cause the EVA material to be pulled off.

[0069] Compared with the prior art, the present application provides a physical recycling method and system for waste silicon photovoltaic laminated piece, which includes three basic links of liquid nitrogen soaking, mechanical peeling and mechanical friction. The waste silicon photovoltaic laminated piece comes from the dense laminated structure after the frame and the junction box are removed in advance, and is soaked in liquid nitrogen. After taking out, it enters the mechanical peeling link, which is operated by workers to separate the glass panel and the back plate of the waste silicon photovoltaic laminated piece from the silicon chip and collect them respectively. Then the silicon chip is placed in room temperature condition for warming up, and then enters the mechanical friction link, which strips the electrode metal powder, metal wire and other components attached to the silicon chip by the friction device, and obtains mixed electrode metal powder, metal wire and silicon plate. The present application solves the problem that the existing waste silicon laminated piece physical method cannot effectively separate the silicon chip, the glass panel and the back plate, and effectively enriches the electrode metal powder, the metal wire, the silicon plate, the glass panel, the back plate and other materials. These materials can be used for subsequent recycling. The method of the present application does not use any organic solvent, does not exist wet process and heating process, and has the advantages of green and energy saving.

[0070] The specific embodiments of the present application described above do not constitute a limitation on the scope of protection of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method of physical recycling of a spent silicon photovoltaic laminate, characterized in that, The method comprises the following steps: (1) Liquid nitrogen soaking: soaking the waste silicon photovoltaic laminate A in liquid nitrogen for 100-150 s to obtain waste silicon photovoltaic laminate B; (2) Mechanical stripping: separating the waste silicon photovoltaic laminate B and collecting the glass panel, back panel and silicon chip respectively; the waste silicon photovoltaic laminate B is separated in one time within 30 s; if the separation in one time cannot be completed within 30 s, the waste silicon photovoltaic laminate B is returned to step (1) for liquid nitrogen soaking and separation again; The humidity of the environment in steps (1) and (2) is controlled to be less than 50%; (3) Mechanical friction: placing the silicon chip in room temperature for 300 s or more, and then recovering the electrode metal powder, wire and silicon plate through mechanical friction.

2. A physical recycling system of waste silicon photovoltaic laminates, characterized in that, The system adopts the physical recovery method of the waste silicon photovoltaic laminate according to claim 1, and comprises a liquid nitrogen soaking device, a mechanical stripping device and a mechanical friction device; wherein The liquid nitrogen soaking device is used for liquid nitrogen soaking of the waste silicon photovoltaic laminate A; The mechanical stripping device comprises an operation table, a movable knife plate support, a knife plate and a negative pressure fixer, the negative pressure fixer is located above the operation table and is used for fixing the waste silicon photovoltaic laminate B; the knife plate is installed on the movable knife plate support and is parallel to the upper surface of the operation table, the movable knife plate support is installed on the operation table and can drive the knife plate to move in parallel on the upper surface of the operation table, during the movement, the cutting edge of the knife plate always faces the adhesive layer in the waste silicon photovoltaic laminate B, and the waste silicon photovoltaic laminate B is separated to obtain the glass panel, back panel and silicon chip; The mechanical friction device comprises a plurality of friction pieces for stripping the silicon chip to obtain the electrode metal powder, wire and silicon plate; A first sliding rail is arranged on the side of the operation table, and the axis of the first sliding rail is parallel to the upper surface of the operation table; the movable knife plate support is connected with a first roller, and the first roller is located in the first sliding rail and can move back and forth along the first sliding rail; A second sliding rail is arranged on the movable knife plate support, and a second roller is connected with the knife plate, and the second roller is located in the second sliding rail and can move up and down along the second sliding rail.

3. The physical recycling system of waste silicon photovoltaic laminates according to claim 2, characterized in that, The liquid nitrogen soaking device comprises a liquid nitrogen container and a steel structure platform with a size smaller than the liquid nitrogen container, and the liquid level of the liquid nitrogen in the liquid nitrogen container is greater than 20 mm.

4. The physical recycling system of waste silicon photovoltaic laminates of claim 2, wherein, The friction pieces are arranged side by side, and holes are arranged on the friction pieces; the mechanical friction device further comprises a feeding roller and a discharging roller for conveying the silicon chip, and a screen for screening the electrode metal powder and wire, the feeding roller and the discharging roller are arranged at two ends of the friction pieces respectively, and the screen is arranged below the friction pieces.

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