Deplating agent and method for stripping, separating and recovering copper and tin from photovoltaic welding strip and welding wire

Abstract

The invention belongs to the technical field of metal resource recovery, and particularly relates to a deplating agent and a method for separating and recovering copper and tin through deplating of a photovoltaic welding strip and a welding wire. The method comprises the steps that firstly, a tin-plated photovoltaic welding strip welding wire is pretreated, so that part of a tin-plated layer is separated from the photovoltaic welding strip welding wire; secondly, uniformly mixing a deplating agent, heating the deplating agent in a crucible until the deplating agent is molten, and uniformly stirring; then the pretreated photovoltaic welding strip welding wire is put into the molten deplating agent, and the soaking time of the photovoltaic welding strip welding wire in the melt is 0.5-50 minutes; then, the photovoltaic welding strip welding wire obtained after full reaction is taken out of the deplating agent melt, centrifugal treatment is carried out, and the deplating agent melt left on the surface of the photovoltaic welding strip welding wire is separated; then, the photovoltaic welding strip welding wire is placed in a diluted hydrochloric acid solution to be cleaned and dried, and a metal copper strip copper wire is obtained; and finally, a product formed after the tin coating reacts with the deplating agent melt is separated, and tin is finally recycled in the forms of salt and metal elementary substances.

Description

Technical Field

[0001] This invention belongs to the field of metal resource recycling technology, specifically relating to a method for stripping and separating copper and tin from photovoltaic solder ribbon and welding wire. Background Technology

[0002] Photovoltaic soldering ribbon and wire are high-end and crucial copper strip products manufactured using a hot-dip tin plating process. They are widely used not only in the aforementioned solar photovoltaic fields but also in industries such as automotive electronics, precision instruments, and home appliances. There are two methods for tin plating copper strip: chemical and physical. Chemical methods primarily involve electroplating, which requires chemical solutions, causing significant environmental pollution and resulting in slow and inefficient production. Physical methods, primarily hot-dip tin plating, have virtually no environmental impact and offer fast and efficient production. This process involves immersing a clean copper alloy material in molten tin, utilizing the physicochemical reactions at the interface to form a layer of metallic tin on the surface. During hot-dip tin plating, the product must have a high-quality appearance, a uniform and smooth surface with a mirror-like luster, no voids, and good solderability. However, due to oxidation, impurities, and other factors, a large amount of waste tin-plated copper strip and wire is generated during production. Furthermore, the lifespan of photovoltaic products is generally 15-20 years, inevitably leading to the obsolescence of a large quantity of waste photovoltaic soldering ribbon and wire. The thickness of the tin layer on the surface of tin-plated copper strip is generally 10–30 micrometers, with tin accounting for approximately 15% of the mass of photovoltaic welding wire. Tin and copper are both strategically important metallic resources, and their continuous and stable supply is crucial for the development of the national economy and defense industry. Separating and recycling copper and tin from tin-plated copper waste in "urban mines" can conserve scarce copper and tin resources, contribute to the development of my country's low-carbon circular economy, and has significant economic and social benefits.

[0003] Tin has a high solid solubility in copper; for example, at 200℃, 350℃, and 520℃, the solubility of tin in copper can reach 2%, 11%, and 15.8% (mass percentage), respectively. To recycle tin-plated copper waste, direct smelting technology is used, where waste tin-plated copper is directly fed into a copper anode furnace as raw material. Through an oxidation-reduction process, it is smelted and cast into anode plates, which are then electrolytically refined to produce cathode copper. However, direct smelting does not effectively recover tin, resulting in a waste of tin resources. Furthermore, the tin content in the anode plates needs to be controlled, complicating the process and significantly increasing costs. While direct smelting can produce copper-tin alloys and simultaneously recover copper and tin, the types and amounts of impurities in waste from different sources vary, making it difficult to control the quality of the alloy. Although separating and recycling tin-plated copper-based waste is challenging, it is undoubtedly a crucial step in the recycling and reuse of tin-plated copper waste.

[0004] Regarding the stripping and recycling of metal plating, Yuan Wenyi et al. disclosed a persulfate stripping method for the surface metal plating of waste ABS electroplated parts under ultrasonic-assisted treatment in 2022 (Publication No. CN115627477A); Peng Qiao et al. disclosed a rapid stripping method for the surface metal film of tooling in 2023 (Publication No. CN117431541A). In recent years, regarding the separation and recycling of tin-plated copper waste, Fu Jiaqi et al. reviewed the copper-tin separation and recycling technology in waste tin-plated copper materials in 2020 (Energy Research and Management, 2020, Vol. 3, pp. 6-12), introducing separation and recycling technologies such as chemical methods, electrochemical methods, chemical-electrowinning methods, and pyrolysis methods. Chen Liang et al. reported in 2013 the recovery of tin and copper from tin-plated copper needles in electronic feet using room temperature alkaline solution electrolytic detinning technology (Nonferrous Metals (Smelting Section), 2013, Vol. 9, pp. 15-18), with direct recovery rates of 99.7% and 94.5% for copper and tin, respectively. In 2023, Gao Dongrui et al. disclosed a method for preparing electroplating-grade potassium stannate trihydrate using scrap copper wire from tin-plated copper strips (publication number CN117735598A). The method involves electrolyzing the copper wire from the tin-plated copper strip in a potassium hydroxide solution to synthesize a potassium stannate solution, followed by impurity removal and evaporation to obtain electroplating-grade potassium stannate trihydrate. In 2017, Cai Wei et al. disclosed a method for removing the tin plating layer from the surface of copper wire from tin-plated copper strips and a tin-removing additive (publication number CN107299349A). The tin-removing additive consists of 40-60% sodium chloride, 20-35% sodium fluoride, 0-10% calcium fluoride, 20-35% cryolite, and 0-10% graphite powder. The tin-plated copper strip is placed in the tin-removing additive and kept at 300-550℃ for 60-150 min to obtain a tin-removed copper strip. In 2010, Zhou Yihui et al. performed vacuum pyrolysis on waste tin-plated wires at a final temperature of 500℃ to form a solid-liquid two-phase state of copper and tin. At the same time, the plastic sheath on the surface of the wires was pyrolyzed to produce carbon slag. Then, a porous hollow drum was used to separate the liquid tin and carbon slag from the copper wires. However, the processing efficiency was low due to the vacuum environment, and the purity of the separated tin and copper was low, resulting in low tin recovery (Renewable Resources and Circular Economy, 2010, No. 12, pp. 29-32). Summary of the Invention

[0005] The purpose of this invention is to provide a method for separating and recovering copper and tin from photovoltaic soldering wire and stripping agent. This method can efficiently, cost-effectively, and environmentally friendly separate and recover metallic copper and tin from photovoltaic soldering wire and stripping agent, and features low cost, environmental friendliness, and short cycle time.

[0006] The technical solution of this invention is:

[0007] A plating stripping agent, prepared from components comprising the following weight percentages: 0–8.4% sodium chloride, 0–12.5% ​​sodium carbonate, 0–10.4% potassium chloride, 0–57% sodium hydroxide, 0–16% potassium sulfate, 0–5.5% potassium carbonate, 0–23.5% potassium fluoride, 0–18.4% potassium iodide, 0–65% calcium hydroxide, 0–60% potassium hydroxide, 0–25% potassium phosphate, 0–10.5% sodium nitrate, 0–36% potassium pyrophosphate, 0–15.5% sodium sulfide, 0–17.5% sodium tungstate, and 0–35.5% sodium citrate.

[0008] Preferably, the stripping agent is prepared from components comprising the following weight percentages: 3-7% sodium chloride, 5-12.5% ​​sodium carbonate, 2-10.4% potassium chloride, 10-37.5% sodium hydroxide, 0-10% potassium sulfate, 1-5.5% potassium carbonate, 5-15% potassium fluoride, 3-15.5% potassium iodide, 3.5-35% calcium hydroxide, 10-41% potassium hydroxide, 1-16.4% potassium phosphate, 0-9% sodium nitrate, 0-23.1% potassium pyrophosphate, 3.1-13.5% sodium sulfide, 1-16.5% sodium tungstate, and 2-23.5% sodium citrate.

[0009] A method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wires specifically includes the following steps:

[0010] Step 1: The tin-plated photovoltaic welding wire is pre-treated by crushing, cutting, cleaning, drying and centrifugation to separate the tin plating layer from the photovoltaic welding wire.

[0011] Step 2: After mixing the plating stripper evenly, place it in a crucible and heat until it melts, stirring constantly.

[0012] Step 3: Place the pretreated photovoltaic welding strip wire into the molten stripping agent. The immersion time of the photovoltaic welding strip wire in the stripping agent melt is 0.5 to 50 minutes.

[0013] Step 4: Remove the fully reacted photovoltaic welding wire from the stripping agent melt and centrifuge it to separate the residual stripping agent melt on the surface of the photovoltaic welding wire.

[0014] Step 5: Clean and dry the photovoltaic welding wire in a dilute hydrochloric acid solution to obtain metallic copper strip and copper wire.

[0015] Step 6 involves separating the products formed after the tin plating layer reacts with the stripping agent melt, ultimately recovering the tin as salts and elemental metals.

[0016] In the method for stripping and separating copper and tin from photovoltaic welding wire, the centrifugal separation temperature in step 1 of the pretreatment is between 250 and 500°C.

[0017] In the method for stripping, separating and recovering copper and tin from photovoltaic solder ribbon and welding wire, in step 3, the weight ratio of stripping agent to photovoltaic solder ribbon and welding wire is between 1 and 10.

[0018] In the method for stripping and separating copper and tin from photovoltaic welding wire, in step 3, the temperature of the stripping agent melt is controlled at 180-650℃.

[0019] In the method for stripping and separating copper and tin from photovoltaic welding wire, in step 4, the centrifugal separation speed is 500-2500 rpm.

[0020] In the method for stripping, separating, and recovering copper and tin from photovoltaic welding wire, in step 5, the pH value of the dilute hydrochloric acid is between 1 and 5.

[0021] The design concept of this invention is:

[0022] First, based on the difference in melting points between copper and tin in photovoltaic soldering wire, at a certain temperature, metallic copper and tin exist in solid and liquid states respectively. Centrifugal force is used to separate part of the tin plating layer on the surface of the photovoltaic soldering wire from the copper solder. Second, based on the difference in chemical properties between copper and tin in the photovoltaic soldering wire, the photovoltaic soldering wire is placed in a stripping agent for reaction. During the reaction, the tin plating layer on the surface of the photovoltaic soldering wire continuously dissolves and falls off under the action of the stripping agent, while tin salts are formed in the stripping agent until the base copper strip and copper wire are exposed, thereby achieving the purpose of removing the tin plating layer on the surface of the photovoltaic soldering wire.

[0023] The advantages and beneficial effects of this invention are:

[0024] 1. Economic and resource benefits. The photovoltaic welding wire recycling method of this invention yields copper strips and wires with a copper mass percentage >99% and a tin recovery rate >96%. The recycled copper strips and wires, tin salts, and elemental tin can be used in the copper and tin material processing and manufacturing industries, which can significantly alleviate the pressure of copper and tin metal resource shortages and is conducive to the construction of a circular economy.

[0025] 2. Social and Environmental Benefits. This invention uses an alkaline system, free of cyanide and nitric acid, allowing for the recycling of the stripping agent. Furthermore, it generates very little wastewater, helping to reduce the pressure on the ecological environment during the stripping process of photovoltaic solder ribbons and wires. Traditional tin stripping treatments produce large amounts of nitrogen-containing wastewater and nitrogen oxide gases. Improper treatment can cause secondary pollution that poses a significant threat to the ecological environment, including animals, plants, and humans. Therefore, this invention offers significant social and environmental benefits. Attached Figure Description

[0026] Figure 1Unprocessed images include: (a) macroscopic photograph of photovoltaic welding strip wire; (b) optical micrograph of the cross-section of photovoltaic welding strip wire; (c) macroscopic photograph of photovoltaic welding strip wire; and (d) optical micrograph of the cross-section of photovoltaic welding strip wire.

[0027] Figure 2 The following are the results of processing according to Example 1 of the present invention: (a) macroscopic photograph of photovoltaic soldering wire; (b) optical micrograph of the cross section of photovoltaic soldering wire; (c) macroscopic photograph of photovoltaic soldering wire; (d) optical micrograph of the cross section of photovoltaic soldering wire; (e) tin salt formed after the tin plating layer reacts with the stripping agent melt; (f) metallic elemental tin ingot obtained by centrifugal separation pretreatment.

[0028] Figure 3 The following are the results of processing in Example 2 of this invention: (a) macroscopic photograph of photovoltaic soldering wire; (b) optical micrograph of the cross section of photovoltaic soldering wire; (c) macroscopic photograph of photovoltaic soldering wire; (d) optical micrograph of the cross section of photovoltaic soldering wire; (e) tin salt formed after the tin plating layer reacts with the stripping agent melt; (f) elemental tin ingot obtained by centrifugal separation pretreatment.

[0029] Figure 4 The following are the results of processing in Example 3 of this invention: (a) macroscopic photograph of photovoltaic soldering wire; (b) optical micrograph of the cross section of photovoltaic soldering wire; (c) macroscopic photograph of photovoltaic soldering wire; (d) optical micrograph of the cross section of photovoltaic soldering wire; (e) tin salt formed after the tin plating layer reacts with the stripping agent melt; (f) elemental tin ingot obtained by centrifugal separation pretreatment.

[0030] Figure 5 The following are the results of processing in Example 4 of this invention: (a) macroscopic photograph of photovoltaic soldering wire; (b) optical micrograph of the cross section of photovoltaic soldering wire; (c) macroscopic photograph of photovoltaic soldering wire; (d) optical micrograph of the cross section of photovoltaic soldering wire; (e) tin salt formed after the tin plating layer reacts with the stripping agent melt; (f) elemental tin ingot obtained by centrifugal separation pretreatment.

[0031] Figure 6 This is a macroscopic photograph of the photovoltaic welding ribbon and welding wire processed according to Example 5 of the present invention; Figure 7 This is an optical micrograph of the cross-section of the photovoltaic welding wire after processing in Example 5 of the present invention; Figure 8 This is a macroscopic photograph of the photovoltaic welding ribbon and welding wire processed according to Example 5 of the present invention; Figure 9 This is an optical micrograph of the cross-section of the photovoltaic welding wire after processing in Example 5 of the present invention; Figure 10 The tin-plated layer after treatment in Example 5 of this invention reacts with the stripping agent melt to form tin salt; Figure 11 The metal elemental tin ingot obtained by centrifugal separation pretreatment after processing in Example 5 of the present invention. Detailed Implementation

[0032] like Figure 1 As shown, the untreated photovoltaic solder ribbon wire has a bright, uniform, and dense tin plating layer with an average thickness of about 10 to 20 micrometers, and it is tightly bonded to the interface between the substrate copper strip and the copper wire.

[0033] In its specific implementation, this invention provides a method for stripping and recovering copper and tin from photovoltaic solder ribbon wire. First, the tin-plated photovoltaic solder ribbon wire undergoes pretreatment including crushing, cutting, cleaning, drying, and centrifugation to partially detach the tin plating from the wire. Second, a stripping agent is uniformly mixed and placed in a crucible, heated until melted, and stirred evenly. Third, the pretreated photovoltaic solder ribbon wire is immersed in the molten stripping agent, with the temperature controlled between 180 and 650°C, and the immersion time in the molten agent is between 0.5 and 50 minutes. Then, the fully reacted photovoltaic solder ribbon wire is removed from the molten stripping agent and centrifuged to separate any remaining stripping agent from its surface. Subsequently, the photovoltaic solder ribbon wire is cleaned and dried in a dilute hydrochloric acid solution to obtain metallic copper strip wire. Finally, the products formed after the reaction between the tin plating and the molten stripping agent are separated, and the tin is ultimately recovered as salt and elemental metal.

[0034] The invention will now be described in further detail through embodiments.

[0035] Example 1

[0036] In this embodiment, the method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire is as follows:

[0037] First, 50 grams of photovoltaic solder wire were cleaned, dried, and cut into sections. These sections were then centrifuged at 250°C to remove some of the tin plating. Next, 112 grams of stripping agent (by weight percentage, consisting of 6.5% sodium chloride, 7.5% sodium carbonate, 2% potassium chloride, 6% potassium sulfate, 1.5% potassium carbonate, 9.5% potassium fluoride, 6.3% potassium iodide, 11.8% sodium hydroxide, 17% potassium hydroxide, 6.5% sodium sulfide, 11.3% calcium hydroxide, 3.5% sodium nitrate, 2.5% potassium phosphate, 2.2% potassium pyrophosphate, 2.3% sodium tungstate, and 3.6% sodium citrate) were thoroughly mixed and placed in a crucible. The mixture was heated until melted and stirred until homogeneous. The pre-treated photovoltaic solder wire was then placed into the molten stripping agent, and the reaction temperature was controlled at 350°C for 25 minutes. After the reaction is complete, the photovoltaic solder wire is removed from the stripping flux and centrifuged at 1500 rpm to separate the residual stripping flux from the surface of the photovoltaic solder wire. The stripped photovoltaic solder wire is then washed in dilute hydrochloric acid (pH 2) and dried to obtain metallic copper strip wire. Finally, the product formed after the reaction of the tin plating layer with the stripping flux is separated from the stripping flux to obtain tin salt.

[0038] Chemical analysis showed that, by mass percentage, the average weight percentage of metallic tin on the surface of the obtained copper strip and copper wire was 0.32%. Simultaneously, the tin plating layer of the photovoltaic soldering wire was recovered in the form of elemental metallic tin and tin salts, with a tin recovery rate of 97.8%. Therefore, it is evident that by adopting this implementation scheme, metallic copper and tin in photovoltaic soldering wire can be recovered in a green and efficient manner.

[0039] like Figure 2 As shown in Example 1, the photovoltaic welding wire treated with the tin plating layer has a good removal effect and the surface of the copper strip and wire is smooth. The tin plating layer is recovered as powdered tin salt and metallic tin ingot, achieving the effect of separating and recovering metallic copper and tin from the photovoltaic welding wire, which can be recycled in the production and processing of copper and tin materials.

[0040] Example 2

[0041] In this embodiment, the method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire is as follows:

[0042] First, 50 grams of photovoltaic solder wire were cleaned, dried, and cut into sections. These sections were then centrifuged at 250°C to remove some of the tin plating. Next, 112 grams of stripping agent (composed of 5% sodium chloride, 9% sodium carbonate, 8% potassium chloride, 1.5% potassium carbonate, 9.5% potassium fluoride, 6.3% potassium iodide, 11.8% sodium hydroxide, 13.5% potassium hydroxide, 11.3% calcium hydroxide, 3.5% sodium nitrate, 4.7% potassium phosphate, 10% sodium sulfide, 2.3% sodium tungstate, and 3.6% sodium citrate, by weight percentage) were mixed thoroughly and placed in a crucible. The mixture was heated until melted and stirred until homogeneous. The pre-treated photovoltaic solder wire was then placed into the molten stripping agent, and the reaction temperature was controlled at 350°C for 25 minutes. After the reaction is complete, the photovoltaic solder wire is removed from the stripping flux and centrifuged at 1500 rpm to separate the residual stripping flux from the surface of the photovoltaic solder wire. The stripped photovoltaic solder wire is then washed in dilute hydrochloric acid (pH 2) and dried to obtain metallic copper strip wire. Finally, the product formed after the reaction of the tin plating layer with the stripping flux is separated from the stripping flux to obtain tin salt.

[0043] Chemical analysis showed that, by mass percentage, the average weight percentage of metallic tin on the surface of the obtained copper strip and copper wire was 0.38%. Simultaneously, the tin plating layer of the photovoltaic solder wire was recovered in the form of elemental metallic tin and tin salts, with a tin recovery rate of 97%. Therefore, using this embodiment, metallic copper and tin in the photovoltaic solder wire can be recovered in a green and efficient manner. Compared with Example 1, the stripping agent ratio in this embodiment is slightly different, but it has little impact on the recovery effect of copper and tin in the photovoltaic solder wire.

[0044] like Figure 3 As shown in Example 2, the photovoltaic welding wire treated with the tin plating layer has a good removal effect and the copper strip and wire obtained have a smooth surface. The tin plating layer is recovered as powdered tin salt and metallic tin ingots, achieving the effect of separating and recovering metallic copper and tin from the photovoltaic welding wire, which can be recycled in the production and processing of copper and tin materials.

[0045] Example 3

[0046] In this embodiment, the method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire is as follows:

[0047] First, 50 grams of photovoltaic solder wire were cleaned, dried, and cut into sections. These sections were then centrifuged at 250°C to remove some of the tin plating. Next, 112 grams of stripping agent (composed of 5% sodium chloride, 9% sodium carbonate, 8% potassium chloride, 1.5% potassium carbonate, 9.5% potassium fluoride, 6.3% potassium iodide, 11.8% sodium hydroxide, 13.5% potassium hydroxide, 11.3% calcium hydroxide, 3.5% sodium nitrate, 4.7% potassium phosphate, 10% sodium sulfide, 2.3% sodium tungstate, and 3.6% sodium citrate, by mass percentage) were mixed thoroughly and placed in a crucible. The mixture was heated until melted and stirred until homogeneous. The pre-treated photovoltaic solder wire was then placed into the molten stripping agent, and the reaction temperature was controlled at 350°C for 15 minutes. After the reaction is complete, the photovoltaic solder wire is removed from the stripping flux and centrifuged at 1500 rpm to separate the residual stripping flux from the surface of the photovoltaic solder wire. The stripped photovoltaic solder wire is then washed in dilute hydrochloric acid (pH 2) and dried to obtain metallic copper strip wire. Finally, the product formed after the reaction of the tin plating layer with the stripping flux is separated from the stripping flux to obtain tin salt.

[0048] Chemical analysis showed that, by mass percentage, the average weight percentage of metallic tin on the surface of the obtained copper strip and copper wire was 0.54%. Simultaneously, the tin plating layer of the photovoltaic solder wire was recovered in the form of elemental metallic tin and tin salts, with a tin recovery rate of 97.2%. Therefore, using this embodiment, metallic copper and tin in the photovoltaic solder wire can be recovered in a green and efficient manner. Compared with Example 2, this embodiment has a shorter processing time and minimal impact on the recovery effect of metallic copper and tin in the photovoltaic solder wire, which is significant for reducing energy consumption.

[0049] like Figure 4 As shown in Example 3, the photovoltaic welding wire treated with the tin plating layer has a good removal effect and the copper strip and wire obtained have a smooth surface. The tin plating layer is recovered as powdered tin salt and metallic tin ingots, achieving the effect of separating and recovering metallic copper and tin from the photovoltaic welding wire, which can be recycled in the production and processing of copper and tin materials.

[0050] Example 4

[0051] In this embodiment, the method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire is as follows:

[0052] First, 50 grams of photovoltaic solder wire were cleaned, dried, and cut into sections. These sections were then centrifuged at 250°C to remove some of the tin plating. Next, 112 grams of stripping agent (composed of 5% sodium chloride, 9% sodium carbonate, 8% potassium chloride, 1.5% potassium carbonate, 9.5% potassium fluoride, 6.3% potassium iodide, 11.8% sodium hydroxide, 13.5% potassium hydroxide, 11.3% calcium hydroxide, 3.5% sodium nitrate, 4.7% potassium phosphate, 10% sodium sulfide, 2.3% sodium tungstate, and 3.6% sodium citrate, by weight percentage) were mixed thoroughly and placed in a crucible. The mixture was heated until melted and stirred until homogeneous. The pre-treated photovoltaic solder wire was then placed into the molten stripping agent, and the reaction temperature was controlled at 400°C for 5 minutes. After the reaction is complete, the photovoltaic solder wire is removed from the stripping flux and centrifuged at 1500 rpm to separate the residual stripping flux from the surface of the photovoltaic solder wire. The stripped photovoltaic solder wire is then washed in dilute hydrochloric acid (pH 2) and dried to obtain metallic copper strip wire. Finally, the product formed after the reaction of the tin plating layer with the stripping flux is separated from the stripping flux to obtain tin salt.

[0053] Chemical analysis showed that, by mass percentage, the average weight percentage of metallic tin on the surface of the obtained copper strip and copper wire was 0.19%. Simultaneously, the tin plating layer of the photovoltaic solder wire was recovered in the form of elemental metallic tin and tin salts, with a tin recovery rate of 98.1%. Therefore, using this embodiment, metallic copper and tin in the photovoltaic solder wire can be recovered in a green and efficient manner. Compared with Example 3, this embodiment has a higher processing temperature and a shorter processing time, but it has little impact on the recovery effect of metallic copper and tin in the photovoltaic solder wire.

[0054] like Figure 5 As shown in Example 4, the photovoltaic welding wire treated with the tin plating layer has a good removal effect and the copper strip and wire obtained have a smooth surface. The tin plating layer is recovered as powdered tin salt and metallic tin ingots, achieving the effect of separating and recovering metallic copper and tin from the photovoltaic welding wire, which can be recycled in the production and processing of copper and tin materials.

[0055] Example 5

[0056] In this embodiment, the method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire is as follows:

[0057] First, 50 grams of photovoltaic solder wire are cleaned, dried, and cut into sections. These sections are then centrifuged at 250°C to remove some of the tin plating. Next, 80 grams of stripping agent (composed of 5% sodium chloride, 9% sodium carbonate, 8% potassium chloride, 1.5% potassium carbonate, 9.5% potassium fluoride, 6.3% potassium iodide, 11.8% sodium hydroxide, 13.5% potassium hydroxide, 11.3% calcium hydroxide, 3.5% sodium nitrate, 4.7% potassium phosphate, 10% sodium sulfide, 2.3% sodium tungstate, and 3.6% sodium citrate, by weight percentage) are mixed thoroughly and placed in a crucible. The mixture is heated until melted and stirred until homogeneous. The pre-treated photovoltaic solder wire is then placed into the molten stripping agent, and the reaction temperature is controlled at 400°C for 5 minutes. After the reaction is complete, the photovoltaic solder wire is removed from the stripping flux and centrifuged at 1500 rpm to separate the residual stripping flux from the surface of the photovoltaic solder wire. The stripped photovoltaic solder wire is then washed in dilute hydrochloric acid (pH 2) and dried to obtain metallic copper strip wire. Finally, the product formed after the reaction of the tin plating layer with the stripping flux is separated from the stripping flux to obtain tin salt.

[0058] Chemical analysis showed that, by mass percentage, the average weight percentage of metallic tin on the surface of the obtained copper strip and copper wire was 0.58%. Simultaneously, the tin plating layer of the photovoltaic solder wire was recovered in the form of elemental metallic tin and tin salts, with a tin recovery rate of 96.5%. Therefore, this embodiment demonstrates that metallic copper and tin in photovoltaic solder wire can be recovered in a green and efficient manner. Compared to Example 4, this embodiment reduces the amount of stripping agent used, but has little impact on the recovery effect of metallic copper and tin in the photovoltaic solder wire, indicating that the amount of stripping agent can be appropriately reduced for the recycling of photovoltaic solder wire.

[0059] like Figures 6-11 As shown in Example 5, the photovoltaic welding wire treated with the tin plating layer has a good removal effect and the surface of the copper strip and wire is smooth. The tin plating layer is recovered as powdered tin salt and metallic tin ingot, achieving the effect of separating and recovering metallic copper and tin from the photovoltaic welding wire, which can be recycled in the production and processing of copper and tin materials.

[0060] The above examples are only for illustrating the present invention. In addition, there are many other different embodiments, and these embodiments are all conceived by those skilled in the art after understanding the concept of the present invention, so they will not be listed one by one here.

Claims

1. A plating stripping agent, characterized in that, The stripping agent is prepared from the following components in weight percentages: 0–8.4% sodium chloride, 0–12.5% ​​sodium carbonate, 0–10.4% potassium chloride, 0–57% sodium hydroxide, 0–16% potassium sulfate, 0–5.5% potassium carbonate, 0–23.5% potassium fluoride, 0–18.4% potassium iodide, 0–65% calcium hydroxide, 0–60% potassium hydroxide, 0–25% potassium phosphate, 0–10.5% sodium nitrate, 0–36% potassium pyrophosphate, 0–15.5% sodium sulfide, 0–17.5% sodium tungstate, and 0–35.5% sodium citrate.

2. The plating stripping agent according to claim 1, characterized in that, Preferably, the stripping agent is prepared from components comprising the following weight percentages: 3-7% sodium chloride, 5-12.5% ​​sodium carbonate, 2-10.4% potassium chloride, 10-37.5% sodium hydroxide, 0-10% potassium sulfate, 1-5.5% potassium carbonate, 5-15% potassium fluoride, 3-15.5% potassium iodide, 3.5-35% calcium hydroxide, 10-41% potassium hydroxide, 1-16.4% potassium phosphate, 0-9% sodium nitrate, 0-23.1% potassium pyrophosphate, 3.1-13.5% sodium sulfide, 1-16.5% sodium tungstate, and 2-23.5% sodium citrate.

3. A method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbons and wires using the stripping agent described in any one of claims 1 to 2, characterized in that, Specifically, the following steps are included: Step 1: The tin-plated photovoltaic welding wire is pre-treated by crushing, cutting, cleaning, drying and centrifugation to separate the tin plating layer from the photovoltaic welding wire. Step 2: After mixing the plating stripper evenly, place it in a crucible and heat until it melts, stirring constantly. Step 3: Place the pretreated photovoltaic welding strip wire into the molten stripping agent. The immersion time of the photovoltaic welding strip wire in the stripping agent melt is 0.5 to 50 minutes. Step 4: Remove the fully reacted photovoltaic welding wire from the stripping agent melt and centrifuge it to separate the residual stripping agent melt on the surface of the photovoltaic welding wire. Step 5: Clean and dry the photovoltaic welding wire in a dilute hydrochloric acid solution to obtain metallic copper strip and copper wire. Step 6 involves separating the products formed after the tin plating layer reacts with the stripping agent melt, ultimately recovering the tin as salts and elemental metals.

4. The method for stripping, separating, and recovering copper and tin from photovoltaic welding wire according to claim 3, characterized in that, In step 1, the pretreatment temperature for centrifugation is between 250 and 500°C.

5. The method for stripping, separating, and recovering copper and tin from photovoltaic welding wire according to claim 3, characterized in that, In step 3, the weight ratio of the stripping agent to the photovoltaic welding wire is between 1 and 10.

6. The method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire according to claim 3, characterized in that, In step 3, the temperature of the stripping agent melt is controlled between 180 and 650°C.

7. The method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire according to claim 3, characterized in that, In step 4, the centrifugation speed is 500-2500 rpm.

8. The method for stripping, separating, and recovering copper and tin from photovoltaic solder ribbon wire according to claim 3, characterized in that, In step 5, the pH value of the dilute hydrochloric acid is between 1 and 5.

Images