Method for recycling photovoltaic solder strips

Abstract

The application relates to a recycling method of a photovoltaic welding strip, which comprises the following steps: performing an oxidation-reduction reaction on the photovoltaic welding strip and a sulfuric acid solution; separating the system after the oxidation-reduction reaction to obtain lead sulfate precipitate, copper wire and a tin-containing solution; mixing and stirring the tin-containing solution and an adsorbent, so that the adsorbent is connected with tin ions in the tin-containing solution through coordination bonds to adsorb the tin ions; performing solid-liquid separation on the system after the adsorption, treating the obtained adsorbent with a basic reagent with a pH greater than or equal to 13; performing solid-liquid separation on the system after the treatment with the basic reagent, and obtaining a tin-containing precipitate through evaporation concentration and cooling crystallization of the obtained liquid part. The recycling method of the photovoltaic welding strip can realize step-by-step recycling of valuable and harmful components in the photovoltaic welding strip, and has the advantages of simple process, low cost, non-use of heat treatment and distillation equipment, and the like, and the sulfuric acid solution and the adsorbent used can be regenerated and utilized, and the method is environment-friendly.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module recycling, and in particular to a method for recycling photovoltaic solder ribbon. Background Technology

[0002] Photovoltaic modules were first introduced in 2000, and the first batch of modules with a lifespan of 20-30 years are about to be retired. With increasingly severe environmental problems, recycling used photovoltaic modules to achieve a closed loop is crucial for resource reuse and environmental protection.

[0003] Photovoltaic solder ribbon, also known as tin-plated copper ribbon or tin-coated copper ribbon, is mainly composed of copper wire with a tin-lead alloy plating. In crystalline silicon solar panels, it primarily functions to focus and transmit current. On the one hand, photovoltaic solder ribbon contains large amounts of valuable metals copper and tin, making it highly valuable for recycling; on the other hand, it contains large amounts of the heavy metal lead, posing a serious threat to the environment. This makes recycling the large quantities of photovoltaic solder ribbon from discarded solar panels a pressing issue with significant economic and environmental implications.

[0004] However, the current recycling process for photovoltaic welding ribbon still faces problems such as high operational difficulty, high equipment cost, and environmental unfriendliness. Summary of the Invention

[0005] Based on this, some embodiments of this application provide a method for recycling photovoltaic welding ribbon, which has the advantages of simple operation, low cost and environmental friendliness.

[0006] A method for recycling photovoltaic solder ribbon includes the following steps:

[0007] The photovoltaic ribbon undergoes an oxidation-reduction reaction with the sulfuric acid solution.

[0008] The system after the redox reaction was separated to obtain lead sulfate precipitate, copper wire, and tin-containing solution;

[0009] The tin-containing solution is mixed and stirred with the adsorbent, so that the adsorbent is connected to the tin ions in the tin-containing solution through coordination bonds and adsorbs the tin ions.

[0010] The system after adsorption was subjected to solid-liquid separation, and the adsorbent containing the tin ions was treated with an alkaline reagent with pH ≥ 13.

[0011] The system treated with the alkaline reagent was subjected to solid-liquid separation. The resulting liquid portion was concentrated by evaporation and then cooled and crystallized to obtain a tin-containing precipitate.

[0012] In some embodiments, the solid-liquid ratio of the photovoltaic ribbon to the sulfuric acid solution is 1:(15~20)g / mL.

[0013] In some embodiments, the sulfuric acid solution has a mass percentage concentration of 3% to 5%.

[0014] In some embodiments, copper is added during the step of redox reaction of the photovoltaic ribbon with sulfuric acid solution, and the copper is loaded on a portion of the photovoltaic ribbon.

[0015] In some embodiments, the redox reaction takes 3 to 5 hours.

[0016] In some embodiments, the solid-liquid ratio of the adsorbent to the tin-containing solution is 1:(1~1.5) g / mL; and / or,

[0017] The tin-containing solution and the adsorbent are mixed and stirred at a temperature of 45℃~55℃ for 2h~3h.

[0018] In some embodiments, the adsorbent comprises dopamine-modified clay material.

[0019] In some embodiments, the clay material includes one or more of sepiolite, montmorillonite, bentonite, and kaolin.

[0020] In some embodiments, the clay material includes sepiolite.

[0021] In some embodiments, the preparation steps of the dopamine-modified clay material include:

[0022] The clay material is acidified in an acidic solution;

[0023] The acidified clay material was subjected to a hydrothermal reaction with dopamine in an alkaline buffer solution to obtain the dopamine-modified clay material.

[0024] In some embodiments, one or more of the following conditions are met:

[0025] (1) The solid-liquid ratio of the clay material to the acidic solution is 1:(2~5)g / mL;

[0026] (2) The mass ratio of the acidified clay to dopamine is (1~2):(1~2);

[0027] (3) The temperature of the hydrothermal reaction is 65℃~75℃ and the time is 20h~30h.

[0028] In some embodiments, the alkaline reagent includes sodium hydroxide and sodium carbonate, or the alkaline reagent includes potassium hydroxide and potassium carbonate.

[0029] In some embodiments, the alkaline reagent comprises a sodium hydroxide solution and a sodium carbonate solution in a volume ratio of 1:(1~1.3).

[0030] In some embodiments, the concentrations of the sodium hydroxide solution and the sodium carbonate solution are 0.05 mol / L to 0.1 mol / L and 0.1 mol / L to 0.15 mol / L, respectively.

[0031] Traditional photovoltaic solder ribbon recovery methods involve heat treatment and vacuum distillation to recover copper, tin, and lead, but these methods are energy-intensive, costly, and difficult to industrialize. Alternatively, methods such as oxidation, alkaline leaching, and electroplating can be used to recover copper, tin, and lead, but these are difficult to operate, environmentally unfriendly, have high equipment costs, and complex processes. Therefore, this application provides a method for recycling photovoltaic solder ribbon in some embodiments. This method involves reacting the photovoltaic solder ribbon with a sulfuric acid solution via an oxidation-reduction reaction to obtain lead sulfate precipitate, copper wire, and a tin-containing solution. This allows lead in the photovoltaic solder ribbon to be recovered as lead sulfate, and copper as copper wire. The tin-containing solution is then mixed with an adsorbent, which adsorbs tin ions from the solution through coordination, separating them from sulfate and hydrogen ions in the solution. The sulfate and hydrogen ions in the solution can then be recycled as part of the sulfuric acid solution. The adsorbent containing tin ions after separation is treated with an alkaline reagent with pH ≥ 13 to disrupt the coordination between tin ions and the adsorbent. Then, solid-liquid separation is performed, and the resulting liquid portion is evaporated, concentrated, cooled, and crystallized to recover the tin ions in the form of precipitate. At the same time, the adsorbent is regenerated and recycled.

[0032] Therefore, the above-mentioned recycling method for photovoltaic welding ribbon can realize the stepwise recovery of valuable metals and harmful components in photovoltaic welding ribbon. The process is simple, low-cost, does not use heat treatment or distillation equipment, and the sulfuric acid solution and adsorbent used can be recycled, which is environmentally friendly. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of a process flow for recycling photovoltaic solder ribbon according to some embodiments of this application. Detailed Implementation

[0035] To facilitate understanding of this application, a more comprehensive description of the application will be provided below in conjunction with specific embodiments. Preferred embodiments of the application are given in the specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Unless otherwise stated or in case of conflict, the terms or phrases used in this application shall have the following meanings:

[0038] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0039] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0040] In this application, "one or more" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0041] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0042] In this document, terms such as "further," "even further," "especially," "for example," "as," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later. However, they should not be construed as limitations on the preceding technical solution or on the scope of protection of this document. Unless otherwise specified, A (as in B) indicates that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0043] In this document, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "present" or "absent." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. In this application, descriptions such as "optionally contains" and "optionally includes" indicate "contains or does not contain." "Optional component X" indicates whether component X exists or does not exist, or whether component X is contained or not.

[0044] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0045] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0046] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this application, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0047] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0048] This application provides a method for recycling photovoltaic solder ribbon. Please refer to [link / reference]. Figure 1 It includes the following steps:

[0049] Step S110: Allow the photovoltaic ribbon to undergo a redox reaction with the sulfuric acid solution.

[0050] Step S120: Separate the system after the redox reaction to obtain lead sulfate precipitate, copper wire and tin-containing solution.

[0051] Step S130: Mix and stir the tin-containing solution with the adsorbent, so that the adsorbent can adsorb tin ions by connecting with tin ions in the tin-containing solution through coordination bonds.

[0052] Step S140: Perform solid-liquid separation on the adsorbed system, and treat the adsorbent with adsorbed tin ions with an alkaline reagent of pH ≥ 13.

[0053] Step S150: The system treated with alkaline reagent is subjected to solid-liquid separation. The resulting liquid portion is concentrated by evaporation and then cooled and crystallized to obtain a tin-containing precipitate.

[0054] The aforementioned method for recycling photovoltaic solder ribbon involves reacting the photovoltaic solder ribbon with a sulfuric acid solution via an oxidation-reduction reaction to obtain lead sulfate precipitate, copper wire, and a tin-containing solution. This allows lead in the photovoltaic solder ribbon to be recovered as lead sulfate, and copper as copper wire. The tin-containing solution is then mixed with an adsorbent, which adsorbs tin ions from the solution through coordination, separating them from sulfate and hydrogen ions. The sulfate and hydrogen ions in the solution can then be recycled as sulfuric acid. The adsorbent containing the separated tin ions is treated with an alkaline reagent with a pH ≥ 13, followed by evaporation, concentration, cooling, and crystallization to recover the tin ions as a precipitate. This process simultaneously regenerates and recycles the adsorbent.

[0055] Therefore, the above-mentioned photovoltaic ribbon recycling method achieves the stepwise full recovery of valuable metals such as copper, tin and lead and harmful components in the ribbon through oxidation-reduction reaction and suitable adsorbent. Copper is recovered in the form of copper wire, lead is recovered in the form of lead sulfate, and tin is recovered in the form of precipitate. The process is simple, low-cost, does not use heat treatment or distillation equipment, and the sulfuric acid solution and adsorbent used can be recycled, which is environmentally friendly.

[0056] In some embodiments, prior to step S110, a step of cleaning and drying the photovoltaic solder ribbon is included. Specifically, the photovoltaic solder ribbon is cleaned with water to remove surface contaminants.

[0057] In some embodiments, the solid-liquid ratio of the photovoltaic solder ribbon to the sulfuric acid solution is 1:(15~20) g / mL. Exemplarily, the solid-liquid ratio of the photovoltaic solder ribbon to the sulfuric acid solution can be, but is not limited to, 1:15 g / mL, 1:16 g / mL, 1:17 g / mL, 1:18 g / mL, 1:19 g / mL, 1:20 g / mL, or any combination of these values. A solid-liquid ratio of the photovoltaic solder ribbon to the sulfuric acid solution within the above range is beneficial for ensuring sufficient reaction between the photovoltaic solder ribbon and the sulfuric acid solution, while simultaneously reducing waste of the sulfuric acid solution.

[0058] In some embodiments, in step S110, the mass percentage concentration of the sulfuric acid solution is 3% to 5%. For example, the mass percentage concentration of the sulfuric acid solution can be, but is not limited to, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, or any combination of these values. It is understood that the above only provides a specific concentration of the sulfuric acid solution, but is not limited to this. In other embodiments, the concentration of the sulfuric acid solution can also be other concentrations, as long as the sulfuric acid solution reacts with the metallic tin and lead in the photovoltaic solder ribbon without passivation.

[0059] In some embodiments, during the step of conducting a redox reaction between the photovoltaic solder ribbon and the sulfuric acid solution, metallic copper is also added, with the copper loaded onto a portion of the photovoltaic solder ribbon. By loading the metallic copper onto a portion of the photovoltaic solder ribbon, a galvanic cell is formed with the solder layer of the photovoltaic solder ribbon and the sulfuric acid solution, accelerating the reaction. Specifically, in step S110, the reaction is initiated and promoted by metallic copper, and the specific positive and negative electrode reactions are as follows: the generated lead ions and sulfate ions combine to form lead sulfate precipitate.

[0060] Positive electrode: Sn-2e - →Sn 2+ Pb-2e - →Pb 2+ ;

[0061] Negative electrode: 2H + +2e - →H2.

[0062] In one embodiment, the metallic copper is in the form of copper wire. Using copper wire allows for the direct use of copper wire recycled from photovoltaic solder ribbons, achieving recycling, and also facilitates the loading of metallic copper onto the photovoltaic solder ribbon. It is understood that in other embodiments, the metallic copper is not limited to the form of copper wire.

[0063] Specifically, there are no particular limitations on the method of loading metal onto the photovoltaic solder ribbon after recycling; as long as the two are in contact, it is acceptable. For example, copper wire can be wound around the photovoltaic solder ribbon.

[0064] In some embodiments, the redox reaction takes 3 to 5 hours. Exemplarily, the reaction time may be, but is not limited to, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, or any combination of these values.

[0065] In some embodiments, prior to step S110, the oxide on the surface of the copper metal is removed. Specifically, the oxide on the surface of the copper metal can be removed by sanding with sandpaper.

[0066] In a specific example, step S110 includes: loading metallic copper onto a portion of the photovoltaic ribbon and carrying out a redox reaction in a sulfuric acid solution with a mass percentage concentration of 3% to 5% for 3 to 5 hours, wherein the solid-liquid ratio of the photovoltaic ribbon to the sulfuric acid solution is 1:(15 to 20) g / mL.

[0067] It is understood that in some other embodiments, copper may not be added in step S110, in which case the reaction rate is relatively slow and the time is longer.

[0068] In some embodiments, the step of separating the system after the redox reaction includes: ultrasonically treating the system after the redox reaction, then removing the copper wire, filtering and separating it to obtain lead sulfate precipitate and tin-containing solution.

[0069] The copper wire separated in step S120 can be reused subsequently. The obtained lead sulfate precipitate is dried and the lead is recovered.

[0070] In some embodiments, in step S130, the solid-liquid ratio of the adsorbent to the tin-containing solution is 1:(1~1.5) g / mL. For example, the solid-liquid ratio of the adsorbent to the tin-containing solution may be, but is not limited to, 1:1 g / mL, 1:1.1 g / mL, 1:1.2 g / mL, 1:1.3 g / mL, 1:1.4 g / mL, 1:1.5 g / mL, or any range of two of these values.

[0071] In some embodiments, in step S130, the mixing temperature is 45°C to 55°C, and the time is 2 hours to 3 hours. For example, the mixing temperature may be, but is not limited to, 45°C, 46°C, 48°C, 50°C, 52°C, 54°C, 55°C, or any combination of these values.

[0072] In some embodiments, in step S130, the mixing speed is 500 rpm to 800 rpm. For example, the mixing speed may be, but is not limited to, 500 rpm, 520 rpm, 550 rpm, 580 rpm, 600 rpm, 620 rpm, 650 rpm, 680 rpm, 700 rpm, 720 rpm, 750 rpm, 780 rpm, 800 rpm, or a range of any two of these values.

[0073] In some embodiments, step S130 includes: mixing the adsorbent with a tin-containing solution at a solid-liquid ratio of 1:(1~1.5) g / mL, and stirring for 2h~3h at a temperature of 45℃~55℃ and a rotation speed of 500rpm~800rpm, so that the adsorbent adsorbs tin ions by connecting with tin ions in the tin-containing solution through coordination bonds.

[0074] In some embodiments, the adsorbent comprises dopamine-modified clay material.

[0075] Clay materials have advantages such as large specific surface area and numerous pore structures, resulting in good adsorption effects. At the same time, the lone pairs of electrons such as nitrogen and oxygen contained in dopamine can coordinate with metallic tin ions in tin-containing solutions. Therefore, by adsorbing tin-containing solutions with dopamine-modified clay materials, the sulfate and hydrogen ions in the solution can be separated, and the sulfate and hydrogen ions in the solution can be recycled and reused as sulfuric acid solution.

[0076] It is understandable that the adsorbent is not limited to dopamine-modified clay materials, but can also be other adsorbents that can adsorb tin ions by connecting with tin ions through coordination bonds.

[0077] In some embodiments, the clay material includes one or more of sepiolite, montmorillonite, bentonite, and kaolin.

[0078] Optionally, the clay material includes sepiolite.

[0079] In one specific example, the adsorbent includes dopamine-modified sepiolite.

[0080] In some embodiments, the preparation steps of the dopamine-modified clay material include:

[0081] The clay material is acidified in an acidic solution;

[0082] The acidified clay material was subjected to a hydrothermal reaction with dopamine in an alkaline buffer solution to obtain the dopamine-modified clay material.

[0083] Specifically, the solid-liquid ratio of the clay to the acidic solution is 1:(2~5) g / mL. In one example, the acidic solution may be, but is not limited to, a sulfuric acid solution. For example, the acidic solution is a 3 mol / L sulfuric acid solution.

[0084] In one example, the acidification treatment was carried out at a temperature of 85°C for 3 hours.

[0085] Specifically, the mass ratio of acid-treated clay to dopamine is (1~2):(1~2).

[0086] In one example, the hydrothermal reaction was carried out at a temperature of 65°C to 75°C for 20 to 30 hours.

[0087] In one example, the pH of the alkaline buffer is 8.5. For example, the alkaline buffer is a tris(hydroxymethyl)aminomethane solution with a pH of 8.5.

[0088] In one example, the preparation steps of dopamine-modified clay are as follows:

[0089] Clay material was mixed with 3 mol / L sulfuric acid solution at a solid-liquid ratio of 1:(2~5) g / mL and acidified at 85℃ for 3 hours.

[0090] Prepare a tris(hydroxymethyl)aminomethane solution with a pH of 8.5;

[0091] Weigh the acidified clay and dopamine in a mass ratio of (1~2):(1~2), disperse them in the above tris(hydroxymethyl)aminomethane solution, and heat the reaction in a water bath at 65℃~75℃ for 20h~30h. After filtration, washing, drying and grinding, dopamine-modified clay is obtained.

[0092] In step S140, the adsorbed system is subjected to solid-liquid separation, and the resulting liquid portion contains H. + and SO4 2- It can be used as a circulating sulfuric acid. The resulting solid portion, i.e., the adsorbent adsorbed with the tin ions, is treated with an alkaline reagent of pH ≥ 13 to destroy the coordination between the adsorbent and the tin ions, allowing the tin ions to react with the alkaline reagent to obtain soluble stannate.

[0093] In step S150, the system treated with the alkaline reagent undergoes solid-liquid separation. The resulting liquid portion is evaporated, concentrated, and cooled to crystallize, yielding a tin-containing precipitate. This separates tin ions from the adsorbent, allowing for recovery as a precipitate. The resulting solid portion constitutes the adsorbent, enabling its regeneration. The regenerated adsorbent can be recycled. Tin hydroxide precipitate produces stannate at pH ≥ 13, causing the precipitate to dissolve. The alkaline reagent used for regeneration has a pH ≥ 13, thus facilitating adsorbent separation. The tin precipitate can be subsequently recovered through filtration, evaporation, concentration, and cooling crystallization.

[0094] In some embodiments, the evaporation and concentration step involves bringing the solution to saturation. Specifically, the solvent is evaporated, increasing the solution concentration until saturation is achieved. In the cooling and crystallization step, the hot saturated solution is allowed to cool and settle, allowing crystals to precipitate. There are no particular requirements for the specific temperature and time; for example, if the solvent is water, the temperature in the evaporation and concentration step can be greater than or equal to 100°C until the solution reaches saturation. The cooling and crystallization step is sufficient to allow crystals to precipitate.

[0095] In some embodiments, the alkaline reagent includes sodium hydroxide and sodium carbonate, or the alkaline reagent includes potassium hydroxide and potassium carbonate. Using this mixed alkali method ensures, on the one hand, the synergistic effect of the two components ensures complete elution of tin ions, improves the adsorbent regeneration effect, simultaneously accelerates the regeneration reaction rate, and shortens the reaction time; on the other hand, it stabilizes the pH value of the solution, ensuring that tin ions are fully dispersed in the system, facilitating subsequent recovery in the form of precipitation.

[0096] Specifically, the alkaline reagent comprises a sodium hydroxide solution and a sodium carbonate solution in a volume ratio of 1:1 to 1:1.3; or, the alkaline reagent comprises a potassium hydroxide solution and a potassium carbonate solution in a volume ratio of 1:1 to 1:1.3. Further, the concentration of the sodium hydroxide (potassium) solution is 0.05 mol / L to 0.1 mol / L, and the concentration of the sodium carbonate (potassium) solution is 0.1 mol / L to 0.15 mol / L.

[0097] In some embodiments, step S140 includes: performing solid-liquid separation on the adsorbed system, wherein the adsorbent with the adsorbed tin ions is rinsed with a sodium hydroxide solution and a sodium carbonate solution in a volume ratio of 1:(1~1.3), wherein the concentrations of the sodium hydroxide solution and the sodium carbonate solution are 0.05mol / L~0.1mol / L and 0.1mol / L~0.15mol / L, respectively.

[0098] In some embodiments, step S150 includes: performing solid-liquid separation on the system after rinsing with sodium hydroxide solution and sodium carbonate solution, and evaporating, concentrating, cooling and crystallizing the resulting liquid portion to obtain a tin-containing precipitate.

[0099] It should be understood that, Figure 1 This is a schematic flowchart of a photovoltaic solder ribbon recycling method according to an embodiment of this application. Figure 1 The steps in the flowchart shown are displayed sequentially according to the arrows. However, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps; they can be executed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. Their execution order is not necessarily sequential, but can be executed in turn or alternately with at least some of other steps or other sub-steps or stages.

[0100] To make the objectives and advantages of this application clearer, the following detailed description of the photovoltaic ribbon recycling method and its effects, in conjunction with specific embodiments, is provided. It should be understood that the specific embodiments described herein are merely illustrative and should not be construed as limiting the scope of this application. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventionally selected in the art. Experimental methods in the embodiments that do not specify specific conditions were implemented under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0101] Example 1

[0102] This embodiment provides a method for recycling photovoltaic solder ribbon, including the following steps:

[0103] (1) Pretreatment of welding strip: The waste welding strip is cleaned multiple times with deionized water to remove surface dirt, and then dried at a constant temperature of 60°C in a vacuum drying oven.

[0104] (2) Copper wire pretreatment: Select a copper wire, sand it with sandpaper to remove the surface oxides and then set it aside.

[0105] (3) Redox reaction: The pretreated copper wire was wound onto waste solder strip and placed together in a 5% sulfuric acid solution for a redox reaction for 3 hours. The solid-liquid ratio of the waste solder strip to the sulfuric acid solution was 1:20 g / mL. The generated lead ions and sulfate ions combined to form lead sulfate precipitate. After the reaction was completed, the copper wire was sonicated for 30 minutes, then removed and filtered to separate the copper wire, lead sulfate precipitate, and tin-containing solution. The copper wire can be reused, and the lead sulfate precipitate was dried at 60°C in a vacuum drying oven and collected for storage.

[0106] (3) Preparation of adsorbent: Sepiolite and 3 mol / L sulfuric acid solution were weighed at a material-to-liquid ratio of 1:4 g / mL. The sepiolite was placed in 3 mol / L sulfuric acid and acidified at 85℃ for 3 h to obtain acidified sepiolite. A 0.1 mol / L tris(hydroxymethyl)aminomethane solution was prepared and the pH was adjusted to 8.5 with 0.1 mol / L sulfuric acid solution to obtain a buffer solution. The acidified sepiolite and dopamine were weighed at a mass ratio of 1:1 and dispersed in the above buffer solution. The mixture was reacted at 70℃ in a water bath for 24 h. After filtration, washing, drying and grinding, dopamine-modified sepiolite adsorbent was obtained.

[0107] (4) Adsorption of tin ions: The prepared adsorbent is placed in the tin-containing solution obtained in step (2) at a material-to-liquid ratio of 1:1 g / mL. The adsorbent is magnetically stirred at 50°C and 700 rpm for 3 hours to allow the adsorbent to adsorb tin ions.

[0108] (5) Adsorbent regeneration and tin ion recovery: After filtering the system where the above adsorption has been completed, the filtrate contains only H+. + and SO4 2- It can be used as recycled sulfuric acid. The filtered adsorbent can be treated by rinsing with a mixed solution of 0.1 mol / L sodium hydroxide and 0.1 mol / L sodium carbonate in a 1:1 volume ratio, followed by solid-liquid separation to regenerate the adsorbent. Simultaneously, the liquid obtained after rinsing is evaporated and concentrated to saturate the solution, then cooled and crystallized to recover tin as sodium stannate. The regenerated adsorbent can be recycled.

[0109] Example 2

[0110] This embodiment provides a method for recycling photovoltaic solder ribbon, which is similar to the method for recycling photovoltaic solder ribbon in Embodiment 1, except that the process parameters are different. Details are shown in Table 1.

[0111] Example 3

[0112] This embodiment provides a method for recycling photovoltaic solder ribbon, which is similar to the method for recycling photovoltaic solder ribbon in Embodiment 1, except that the process parameters are different. Details are shown in Table 1.

[0113] Example 4

[0114] This embodiment provides a method for recycling photovoltaic solder ribbon, which is similar to the method for recycling photovoltaic solder ribbon in Embodiment 1. The difference is that it does not contain step (2), and no copper wire is added in the redox reaction of step (3).

[0115] Example 5

[0116] This embodiment provides a method for recycling photovoltaic solder ribbon, which is similar to the method for recycling photovoltaic solder ribbon in Embodiment 1. The difference is that in step (5), the filtered adsorbent is regenerated by rinsing with a sodium hydroxide solution with a concentration of 0.1 mol / L, and tin is recovered in the form of sodium stannate at the same time.

[0117] Comparative Example 1

[0118] Comparative Example 1 provides a method for recycling photovoltaic solder ribbon, which is similar to the method for recycling photovoltaic solder ribbon in Example 1, except that the adsorbent is different. In Comparative Example 1, the adsorbent used is sepiolite that has not been modified with dopamine. The other steps are the same as in Example 1 and will not be described again.

[0119] Table 1. Process parameters of the photovoltaic solder ribbon recycling methods in each embodiment.

[0120]

[0121] The recovery rate and purity of copper, tin and lead recovered by the above-mentioned photovoltaic solder ribbon recycling method were tested, and the experimental data are shown in Table 2 below.

[0122] Table 2 Recovery and purity data for each example and comparative example.

[0123]

[0124] As can be seen from Table 2 above, copper wire, as an initiator, can effectively promote the reaction and significantly improve the recovery rates of copper, tin, and lead. Using a mixed alkali of sodium hydroxide and sodium carbonate to regenerate the adsorbent can stabilize the pH of the solution, ensuring sufficient elution of tin ions, thus improving the regeneration effect and increasing the recovery rate of tin metal. Regarding the modification of the adsorbent, polydopamine-modified montmorillonite can effectively adsorb tin ions, further improving the recovery rate of tin ions.

[0125] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for recycling and processing photovoltaic welding ribbon, characterized in that, Includes the following steps: The photovoltaic ribbon undergoes an oxidation-reduction reaction with the sulfuric acid solution. The system after the redox reaction was separated to obtain lead sulfate precipitate, copper wire, and tin-containing solution; The tin-containing solution is mixed and stirred with the adsorbent, so that the adsorbent is connected to the tin ions in the tin-containing solution through coordination bonds and adsorbs the tin ions. The system after adsorption was subjected to solid-liquid separation, and the adsorbent containing the tin ions was treated with an alkaline reagent with pH ≥ 13. The system treated with the alkaline reagent was subjected to solid-liquid separation. The resulting liquid portion was concentrated by evaporation and then cooled and crystallized to obtain a tin-containing precipitate.

2. The method for recycling and processing photovoltaic welding ribbon according to claim 1, characterized in that, The solid-liquid ratio of the photovoltaic welding ribbon and the sulfuric acid solution is 1:(15~20)g / mL; Optionally, the sulfuric acid solution has a mass percentage concentration of 3% to 5%.

3. The method for recycling photovoltaic welding ribbon according to claim 1 or 2, characterized in that, In the step of causing the photovoltaic ribbon to undergo a redox reaction with sulfuric acid solution, metallic copper is also added, and the metallic copper is loaded on a portion of the photovoltaic ribbon.

4. The method for recycling photovoltaic welding ribbon according to claim 3, characterized in that, The redox reaction takes 3 to 5 hours.

5. The method for recycling photovoltaic welding ribbon according to claim 1, characterized in that, The solid-liquid ratio of the adsorbent to the tin-containing solution is 1:(1~1.5) g / mL; and / or, The tin-containing solution and the adsorbent are mixed and stirred at a temperature of 45℃~55℃ for 2h~3h.

6. The method for recycling photovoltaic welding ribbon according to claim 1 or 5, characterized in that, The adsorbent includes dopamine-modified clay material; Optionally, the clay material includes one or more of sepiolite, montmorillonite, bentonite, and kaolin. Optionally, the clay material includes sepiolite.

7. The method for recycling photovoltaic welding ribbon according to claim 6, characterized in that, The preparation steps of the dopamine-modified clay material include: The clay material is acidified in an acidic solution; The acidified clay material was subjected to a hydrothermal reaction with dopamine in an alkaline buffer solution to obtain the dopamine-modified clay material.

8. The method for recycling photovoltaic welding ribbon according to claim 7, characterized in that, One or more of the following conditions must be met: (1) The solid-liquid ratio of the clay material to the acidic solution is 1:(2~5)g / mL; (2) The mass ratio of the acidified clay to dopamine is (1~2):(1~2); (3) The temperature of the hydrothermal reaction is 65℃~75℃ and the time is 20h~30h.

9. The method for recycling photovoltaic welding ribbon according to claim 1, characterized in that, The alkaline reagent includes sodium hydroxide and sodium carbonate, or the alkaline reagent includes potassium hydroxide and potassium carbonate.

10. The method for recycling photovoltaic welding ribbon according to claim 9, characterized in that, The alkaline reagent includes a sodium hydroxide solution and a sodium carbonate solution in a volume ratio of 1:(1~1.3); Optionally, the concentrations of the sodium hydroxide solution and the sodium carbonate solution are 0.05 mol / L to 0.1 mol / L and 0.1 mol / L to 0.15 mol / L, respectively.

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