Recycling method of crystalline silicon solar cell module

Abstract

The invention relates to a recovery method of a crystalline silicon solar cell module. The recovery method comprises the following steps: S1, dismounting a module frame and a junction box; s2, the first EVA layer is cut through a first tool knife, a material A and a first material are obtained, and the material A comprises the backboard to which a part of the first EVA layer is attached; s3, a second tool knife is adopted to cut the silicon wafer in the first material along the tinned copper strip, a material B and a second material are obtained, and the material B comprises the tinned copper strip attached with the other part of the first EVA layer and a part of the silicon wafer covered by the tinned copper strip; s4, a third tool knife is adopted to cut the second EVA layer, a material C and a third material are obtained, the material C comprises the other part of the silicon wafer and one part of the second EVA layer, and the third material comprises the other part of the second EVA layer and the front plate glass; and S5, the material B and the material C are subjected to heating treatment and hydrometallurgy treatment correspondingly.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a method for recycling a crystalline silicon solar cell assembly. Background Art

[0002] The service life of crystalline silicon solar modules is generally 20 to 25 years. In the future, the number of retired photovoltaic modules will gradually increase. If these retired modules cannot be recycled reasonably and effectively, it will cause waste of resource materials and seriously pollute the environment.

[0003] At present, the industrial technology for recycling crystalline silicon modules is immature, especially in terms of module disassembly, which faces problems such as high cost and serious environmental pollution. For example, the inorganic solvent / organic solvent method of disassembling modules takes a long time, requires a large amount of solvent, and is difficult to handle waste liquid; the thermal treatment decomposition method consumes a lot of energy and produces harmful gases such as hydrofluoric acid; the overall module is crushed and screened or sorted, and the purity of each material is not high, making it difficult to recycle high-purity materials.

[0004] In addition, with the continuous development of photovoltaic technology, the size of solar cells has become larger, the thickness has become thinner, and new processes and highly integrated equipment have emerged. It is difficult to directly reuse the complete silicon wafers on new production lines at a high cost. Therefore, in component recycling, the integrity of silicon wafer recycling is not so important; it is more important to be able to efficiently separate components, save energy and reduce emissions, reduce pollution, obtain high-purity recycled materials and reuse them.

[0005] For example, CN110491969A discloses a method for recycling crystalline silicon photovoltaic modules. After removing the external junction box and aluminum frame of the crystalline silicon photovoltaic module to be recycled, the EVA layers are softened by heating. Then, a metal cutter / metal wire is used to cut along different EVA layers to separate the glass layer, battery cell layer or backplane layer from other parts, and each part can be recycled separately.

[0006] However, the recovery efficiency of silicon and metals by existing recovery methods still needs to be further improved. Summary of the invention

[0007] The purpose of the present invention is to provide a method for recycling crystalline silicon solar cell modules, which can dismantle solar cell modules in an energy-saving and efficient manner through a purely physical method, and obtain different materials that are easier to recycle and process, thereby improving the recycling efficiency.

[0008] In order to achieve the above object, the present invention provides a method for recycling a crystalline silicon solar cell module, wherein the crystalline silicon solar cell module comprises, from bottom to top, a junction box, a back plate, a first EVA layer, a tinned copper strip, a silicon wafer, a second EVA layer, a front plate glass and a module frame, and the recycling method comprises:

[0009] S1, removing the component frame and the junction box;

[0010] S2, using a first utility knife to cut the first EVA layer to obtain material A and a first material, wherein the material A includes the backboard to which a portion of the first EVA layer is attached;

[0011] S3, using a second tool knife to cut the silicon wafer in the first material along the tinned copper tape to obtain material B and a second material, wherein material B includes the tinned copper tape with another portion of the first EVA layer attached thereto and a portion of the silicon wafer covered by the tinned copper tape;

[0012] S4, using a third utility knife to cut the second EVA layer to obtain a material C and a third material, wherein the material C includes another part of the silicon wafer and a part of the second EVA layer, and the third material includes another part of the second EVA layer and the front glass plate;

[0013] S5. Subjecting the material B to a first heating treatment and a first hydrometallurgical treatment, and subjecting the material C to a second heating treatment and a second hydrometallurgical treatment.

[0014] Optionally, in step S2, the thickness of the first EVA layer is 0.5 mm; the thickness of a portion of the first EVA layer is 0.1-0.4 mm.

[0015] Optionally, in step S4, the thickness of the second EVA layer is 0.5 mm; the thickness of a portion of the second EVA layer is 0.1-0.4 mm.

[0016] Optionally, the first tool tool and the third tool tool are each independently a disc milling cutter; and the second tool tool is a cylindrical milling cutter.

[0017] Optionally, the temperature of the first heating treatment is 300-800° C., and the time is 5-90 min.

[0018] Optionally, the temperature of the first heating treatment is preferably 500-600° C., and the time is preferably 10-60 min.

[0019] Optionally, the second heating treatment is performed at a temperature of 300-800° C. and for a time of 5-90 min.

[0020] Optionally, the temperature of the second heating treatment is preferably 500-600° C., and the time is preferably 10-60 min.

[0021] Optionally, the recycling method further comprises: performing pyrolysis treatment on the third material to obtain the front plate glass.

[0022] Optionally, the pyrolysis treatment is carried out at a temperature of 500-600°C and for a time of 10-60 minutes.

[0023] Through the above technical scheme, the present invention adopts milling process, heating treatment and step-by-step hydrometallurgical purification treatment to obtain high-purity silicon, copper, silver, backplane, front plate glass and other materials, and the enrichment of each material is high. Through heating treatment, material B is already granular and highly enriched in copper. Compared with the existing crushing technology, no additional grinding and crushing process is required. It is easier to obtain high-purity metallic copper by hydrometallurgical treatment, while greatly saving process time and cost, and improving recovery efficiency. Compared with the existing crushing technology, material C does not contain glass and backplane. Because the mass proportion of glass and backplane in the component is more than 70%, through the recovery method of the present invention, the mass proportion of silver in the material is more than 70% higher than that of the prior art, so it is also easier to obtain high-purity silver through the silver recovery process, and the use of solvents is greatly reduced, and the silver recovery cost is greatly reduced. The recovery method of the present invention is simple, easy to implement, energy-saving and environmentally friendly, the separated material has high purity, and efficient reuse of resources is achieved.

[0024] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a schematic diagram of the structure of a crystalline silicon solar cell module of the present invention;

[0027] Figure 2 This is a schematic diagram of the present invention after removing the junction box and component frame;

[0028] Figure 3 This is a schematic diagram of the structure after the disc milling cutter is used to remove the back plate and part of the EVA for the first time in the present invention;

[0029] Figure 4 It is a schematic diagram of the second use of a cylindrical milling cutter to remove the tinned copper strip in the present invention;

[0030] Figure 5 This is a schematic diagram of the structure after the disc milling cutter is used to remove the silicon wafer and part of the EVA for the third time in the present invention. DETAILED DESCRIPTION

[0031] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0032] The present invention provides a method for recycling a crystalline silicon solar cell module, wherein the crystalline silicon solar cell module comprises, from bottom to top, a junction box, a back plate, a first EVA layer, a tinned copper strip, a silicon wafer, a second EVA layer, a front plate glass and a module frame, and the recycling method comprises:

[0033] S1, removing the component frame and the junction box;

[0034] S2, using a first utility knife to cut the first EVA layer to obtain material A and a first material, wherein the material A includes the backboard to which a portion of the first EVA layer is attached;

[0035] S3, using a second tool knife to cut the silicon wafer in the first material along the tinned copper tape to obtain material B and a second material, wherein material B includes the tinned copper tape with another portion of the first EVA layer attached thereto and a portion of the silicon wafer covered by the tinned copper tape;

[0036] S4, using a third utility knife to cut the second EVA layer to obtain a material C and a third material, wherein the material C includes another part of the silicon wafer and a part of the second EVA layer, and the third material includes another part of the second EVA layer and the front glass plate;

[0037] S5. Subjecting the material B to a first heating treatment and a first hydrometallurgical treatment, and subjecting the material C to a second heating treatment and a second hydrometallurgical treatment.

[0038] In the present invention, the first tool knife can be used to completely collect the back plate, and the back plate can be effectively collected by purging or vacuum adsorption. Since the back plate contains fluorine, the present invention can avoid fluorine pollution caused by other high-temperature technologies. The second tool knife can be used to obtain a tinned copper strip. In order to remove all the tinned copper strips, a small amount of silicon wafers will be damaged during removal. The tinned copper strips are adhered with another part of the first EVA layer and a few silicon wafers at the same time. Compared with other processes of breaking the entire component, the present invention is easier and more complete to separate, and copper materials can be better enriched. The subsequent copper recovery process will be simpler and the recovery cost will be lower. The third tool knife can be used to separate the silicon wafer (including silver grid lines) and the front plate glass. In order to reduce the fragmentation and sputtering of the silicon wafer and make the separation of silver easier, a part of the second EVA layer will be retained on the silicon wafer, which can better enrich the silicon wafer and the silver-containing grid line material. EVA can be removed by heating material B and material C separately. At the same time, material B and material C become granular, and further hydrometallurgical treatment can be used to obtain silicon particles, high-purity copper, high-purity silver and other metals. Compared with the traditional high-temperature treatment method of the entire component, the present invention can remove EVA faster and more efficiently, and is more energy-efficient. Compared with the existing crushing technology, the present invention does not require additional grinding and crushing processes, and at the same time greatly saves process time and cost, and improves recovery efficiency; and the separated materials are of high purity, realizing efficient reuse of resources.

[0039] According to the present invention, optionally, in step S2, the thickness of the first EVA layer may be 0.5 mm; the thickness of a portion of the first EVA layer may be 0.1-0.4 mm.

[0040] According to the present invention, optionally, in step S4, the thickness of the second EVA layer may be 0.5 mm; the thickness of a portion of the second EVA layer may be 0.1-0.4 mm.

[0041] According to the present invention, optionally, the first tool knife and the third tool knife are each independently a disc milling cutter; the second tool knife is a cylindrical milling cutter. The milling process can realize the separation of the front plate glass, EVA, tinned copper strip, silicon wafer and fluorine-containing back plate of the solar module. The milling machine technology industry is quite mature, and the processing accuracy can reach 0.01-0.02mm, and the surface roughness can reach 3-20μm.

[0042] According to the present invention, optionally, the temperature of the first heat treatment can be 300-800°C, preferably 500-600°C, and the time can be 5-90min, preferably 10-60min. In the above embodiment, the EVA is completely vaporized by the heat treatment, and the material B becomes granular, and a tinned copper strip and a small amount of broken silicon granular material are obtained, and silicon granules can be obtained by conventional methods such as screening and sorting.

[0043] According to the present invention, optionally, the temperature of the second heat treatment is 300-800°C, preferably 500-600°C, and the time is 5-90min, preferably 10-60min. In the above embodiment, the EVA is completely vaporized by heat treatment, and the material C becomes granular, and silicon particles, silver grid lines and a small amount of aluminum and other metals are obtained. The purity of the silicon particles obtained by the present invention is higher than that of the traditional full-component crushing process, and the silicon particles are easier to purify subsequent high-purity silicon, such as 5N, 6N, 7N, 8N, 9N and other levels of purification. The purification method of high-purity silicon is well known to those skilled in the art and will not be repeated here.

[0044] According to the present invention, optionally, the first hydrometallurgical treatment and the second hydrometallurgical treatment are well known to those skilled in the art and will not be described in detail herein. Through the hydrometallurgical treatment, high-purity metals such as copper and silver can be obtained.

[0045] According to the present invention, optionally, the recycling method further comprises: performing pyrolysis treatment on the third material to obtain the front plate glass.

[0046] According to the present invention, optionally, the temperature of the pyrolysis treatment is 500-600° C. and the time is 10-60 min. In the above embodiment, another part of the second EVA layer can be removed through the pyrolysis treatment to obtain a clean and complete front glass.

[0047] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0048] Example

[0049] See also Figure 2 After removing the junction box and the component frame, the crystalline silicon solar cell module of the present invention includes, from bottom to top: a back plate (taking TPT as an example, 0.35 mm thick), a first EVA layer (0.5 mm thick), a tinned copper strip (0.08 mm-0.25 mm thick), a crystalline silicon cell sheet (0.19 mm thick), a second EVA layer (0.5 mm thick) and a front glass plate (0.5 mm thick).

[0050] In this embodiment, the crystalline silicon solar cell components are recycled by the following steps:

[0051] S1, removing the component frame and the junction box;

[0052] S2, such as Figure 3 As shown, the first EVA layer is cut by a disc milling cutter to obtain material A and a first material, wherein the material A includes the back plate to which a portion of the first EVA layer is attached; the thickness of the portion of the first EVA layer is 0.3 mm;

[0053] S3, such as Figure 4 As shown, a cylindrical milling cutter is used to cut the silicon wafer in the first material along the tinned copper strip to obtain material B and a second material, wherein the material B includes the tinned copper strip with another part of the first EVA layer attached thereto and a part of the silicon wafer covered by the tinned copper strip; the copper mass content in the material B is 30% to 50%, accounting for 90% to 100% of the total copper in the crystalline silicon solar cell module; the silver mass content in the material B is 0.2% to 0.8%, accounting for 25% to 35% of the total silver in the crystalline silicon solar cell module;

[0054] S4, such as Figure 5 As shown, the second EVA layer is cut by a disc milling cutter to obtain material C and a third material, wherein the material C includes another part of the silicon wafer and a part of the second EVA layer, and the thickness of the part of the second EVA layer is 0.3 mm; the third material includes another part of the second EVA layer and the front plate glass; the third material is pyrolyzed at 550° C. for 40 min, and another part of the second EVA layer is removed to obtain the front plate glass; the silicon mass content in the material C is 30% to 60%, accounting for 80% to 90% of the total silicon content in the crystalline silicon solar cell module, and the silver mass content in the material C is 0.5% to 0.8%, accounting for 65% to 75% of the total silver content in the crystalline silicon solar cell module.

[0055] S5, subjecting the material B to a first heating treatment at 550° C. for 40 min, and then subjecting it to a first hydrometallurgical treatment to obtain metal copper and silver. Subjecting the material C to a second heating treatment at 550° C. for 40 min, to obtain silicon particles, silver grid lines and a small amount of aluminum and other metals, and then subjecting it to a second hydrometallurgical treatment to obtain silver, aluminum and other metals.

[0056] Comparative Example

[0057] This comparative example recycles the crystalline silicon solar cell components by the following steps:

[0058] S1. Remove the frame and junction box of the crystalline silicon solar cell module;

[0059] S2, using a metal cutter to peel off the first EVA layer to obtain a backplane and component A attached with the first EVA layer;

[0060] S3, using a metal cutter to peel off the tinned copper strip in the component A to obtain a tinned copper strip and a component B; the copper mass content of the tinned copper strip is 5% to 15%, accounting for 60% to 70% of the total copper in the crystalline silicon solar cell component;

[0061] S4. Use a metal cutter to peel off the second EVA layer in the component B to obtain a silicon wafer and a front glass plate with the second EVA layer attached thereto; the silicon wafer has a silicon mass content of 10% to 20%, accounting for 60% to 75% of the total silicon in the crystalline silicon solar cell module, and a silver mass content of 0.2% to 0.4%, accounting for 45% to 60% of the total silver in the crystalline silicon solar cell module.

[0062] S5, subjecting the tinned copper strip to a first heat treatment at 550° C. for 40 minutes, and then subjecting it to a first hydrometallurgical treatment to obtain metallic copper. Subjecting the silicon wafer to a second heat treatment at 550° C. for 40 minutes to obtain silicon particles, silver-containing grid lines and a small amount of aluminum and other metals, and then subjecting it to a second hydrometallurgical treatment to obtain silver, aluminum and other metals.

[0063] According to the above embodiments and comparative examples, when the EVA layer is removed by the comparative recovery method, the EVA layer is removed cleanly, and the tinned copper strip is not attached to the EVA layer, and the copper material cannot be better enriched; at the same time, the silicon wafer is not attached to the EVA layer, which easily causes the silicon wafer to be broken and sputtered, making the separation of silver difficult, and the silicon wafer and the silver-containing grid wire material cannot be better enriched, which is not conducive to the subsequent purification of metals such as copper and silver by hydrometallurgical treatment. The recovery method of the present invention mainly adopts a milling cutter process through a pure physical method to disassemble the crystalline silicon solar cell module in an energy-saving and efficient manner, and completely realizes the separation of the front plate glass, tinned copper strip, silicon wafer and back plate of the crystalline silicon solar cell module, and the enrichment and purity of each material are high, which is more conducive to the purification of metals and realizes the efficient reuse of resources.

[0064] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0065] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0066] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for recycling crystalline silicon solar cell modules, characterized in that: The crystalline silicon solar cell module comprises, from bottom to top, a junction box, a back plate, a first EVA layer, a tinned copper strip, a silicon wafer, a second EVA layer, a front plate glass and a module frame. The recycling method comprises: S1, removing the component frame and the junction box; S2, using a first utility knife to cut the first EVA layer to obtain material A and a first material, wherein the material A includes the backboard to which a portion of the first EVA layer is attached; S3, using a second tool knife to cut the silicon wafer in the first material along the tinned copper tape to obtain material B and a second material, wherein material B includes the tinned copper tape with another portion of the first EVA layer attached thereto and a portion of the silicon wafer covered by the tinned copper tape; S4, using a third utility knife to cut the second EVA layer to obtain a material C and a third material, wherein the material C includes another part of the silicon wafer and a part of the second EVA layer, and the third material includes another part of the second EVA layer and the front glass plate; S5. Subjecting the material B to a first heating treatment and a first hydrometallurgical treatment, and subjecting the material C to a second heating treatment and a second hydrometallurgical treatment.

2. The recycling method according to claim 1, wherein: In step S2, the thickness of the first EVA layer is 0.5 mm; the thickness of a portion of the first EVA layer is 0.1-0.4 mm.

3. The recovery method according to claim 1 or 2, wherein: In step S4, the thickness of the second EVA layer is 0.5 mm; the thickness of a portion of the second EVA layer is 0.1-0.4 mm.

4. The recycling method according to claim 1, wherein: The first tool cutter and the third tool cutter are each independently a disc milling cutter; the second tool cutter is a cylindrical milling cutter.

5. The recycling method according to claim 1, wherein: The temperature of the first heating treatment is 300-800° C., and the time is 5-90 minutes.

6. The recycling method according to claim 5, wherein: The temperature of the first heating treatment is preferably 500-600° C., and the time is preferably 10-60 min.

7. The recycling method according to claim 1, wherein: The temperature of the second heating treatment is 300-800° C., and the time is 5-90 minutes.

8. The recycling method according to claim 7, wherein: The temperature of the second heating treatment is preferably 500-600° C., and the time is preferably 10-60 min.

9. The recycling method according to claim 1, wherein: The recycling method further comprises: performing pyrolysis treatment on the third material to obtain the front plate glass.

10. The recycling method according to claim 9, wherein: The temperature of the pyrolysis treatment is 500-600° C. and the time is 10-60 minutes.

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