CN-121992409-A - Green stripping solution for photovoltaic solder strip and valuable metal separation and recovery method

Abstract

The invention discloses a green stripping solution for a photovoltaic solder strip and a valuable metal separation and recovery method, wherein the stripping solution is an aqueous solution, solutes comprise a main oxidant, a green acidic auxiliary agent, a complexing auxiliary solvent and a special corrosion inhibitor for copper, the main oxidant is selected from sodium persulfate, ammonium persulfate and ferric nitrate, the green acidic auxiliary agent is selected from sulfamic acid, methanesulfonic acid, tartaric acid and citric acid, the complexing auxiliary solvent is selected from sodium chloride, ammonium chloride and thiourea, and the corrosion inhibitor is selected from benzotriazole, methylbenzotriazole and 2-mercaptobenzimidazole. Immersing the waste solder strips at 20-60 ℃ for reaction, enabling tin, lead and/or silver to enter the solution in the form of complex ions, keeping the copper substrate clean, and carrying out solid-liquid separation by adopting the steps of displacement silver extraction, temperature difference crystallization lead separation and hydrolysis tin precipitation or adding excessive zinc-based displacement agent for full displacement recovery. The separation and recovery method of the invention has the advantages of quick deplating, no white film and low copper loss, and is suitable for silver-containing and silver-free solder strips.

Inventors

• LEI QI
• LI ZHUYUAN
• CHEN XIAOYAN
• ZHAO QIANYU
• HE TIANYI
• ZHANG JINBING
• HU DONGLI

Assignees

• 浙大宁波理工学院

Dates

Publication Date

20260508

Application Date

20260115

Claims (10)

1. 1. The green stripping solution for the photovoltaic solder strip is characterized in that the stripping solution is an aqueous solution, and the solute component of the stripping solution comprises: A main oxidant, a green acid auxiliary agent, a complexing cosolvent and a special corrosion inhibitor for copper; the main oxidant is selected from one or more of sodium persulfate, ammonium persulfate and ferric nitrate; the green acid auxiliary agent is one or more selected from sulfamic acid, methanesulfonic acid, tartaric acid and citric acid; the complexing cosolvent is selected from one or more of sodium chloride, ammonium chloride and thiourea; The special corrosion inhibitor for copper is one or more selected from benzotriazole, methylbenzotriazole and 2-mercaptobenzimidazole.
2. 2. The green stripping solution for photovoltaic solder strips according to claim 1, wherein the mass concentration ranges of the components in the stripping solution are as follows: 50-200g/L of main oxidant; 30-120g/L of green acid auxiliary agent; 20-100g/L of complexing cosolvent; 0.1-2.0g/L of special corrosion inhibitor for copper.
3. 3. The green stripping solution for photovoltaic solder strips according to claim 2, wherein the mass concentration ranges of the components in the stripping solution are as follows: the main oxidant is sodium persulfate with the concentration of 100-150 g/L; The green acid auxiliary agent is sulfamic acid with the concentration of 70-100 g/L; the complexing cosolvent is a mixture of sodium chloride and thiourea, wherein the concentration of the sodium chloride is 30-50 g/L, and the concentration of the thiourea is 5-15 g/L; The special corrosion inhibitor for copper is benzotriazole with the concentration of 0.3-1.0 g/L.
4. 4. The green stripping solution for a photovoltaic solder strip of claim 1, wherein the complexing co-solvent comprises thiourea and the concentration of thiourea is not less than 5 g/L.
5. 5. A method for separating and recovering valuable metals by using the stripping solution according to any one of claims 1 to 4, comprising the steps of: s1, full dissolution deplating: Immersing the waste photovoltaic solder strip in a stripping solution for reaction, and under the action of a main oxidant, a complexing cosolvent and a special corrosion inhibitor for copper, enabling tin, lead and/or silver in a solder strip coating to enter the solution in a soluble complexing ion form, and simultaneously keeping a copper substrate insoluble and forming a bright and clean surface to obtain a stripping waste liquid; s2, solid-liquid separation: and separating the stripping waste liquid from the copper substrate to obtain the stripping waste liquid rich in valuable metal ions and a recovered copper strip.
6. 6. The method for separating and recovering valuable metals from a stripping solution according to claim 5, wherein in the step S1, the reaction is performed under stirring at a temperature of 20-60 ℃ for 10-30 minutes.
7. 7. The method for separating and recovering valuable metals from a stripping solution according to claim 5, wherein the step S2 comprises: S21, replacing and extracting silver, namely adding a copper-based replacement agent into the deplating waste liquid, and carrying out solid-liquid separation after a replacement reaction to obtain metallic silver; S22, lead is separated by temperature difference crystallization, namely the filtrate obtained in the step S21 is heated, concentrated and cooled, lead chloride is separated out by crystallization, and lead chloride crystals and poor lead and tin-rich mother liquor are obtained after solid-liquid separation; S23, carrying out hydrolysis tin precipitation, namely regulating the pH value of the lead-poor and tin-rich mother solution to 1.5-2.5, heating to 70-90 ℃ for hydrolysis reaction, and carrying out solid-liquid separation to obtain tin-containing compound precipitate.
8. 8. The method for separating and recovering valuable metals from a stripping solution according to claim 7, wherein in the step S21, the copper-based displacer is copper sponge powder.
9. 9. The method for separating and recovering valuable metals from a stripping solution according to claim 7, wherein in the step S22, the crystallization temperature is 5-10 ℃.
10. 10. The method for separating and recovering valuable metals from the stripping solution according to claim 5, wherein the step S2 comprises the steps of adding an excessive zinc-based displacer into the stripping waste solution, reducing tin, lead, silver and/or copper ions in the solution into mixed metal mud through a displacement reaction at one time, and carrying out solid-liquid separation to obtain the mixed metal mud, wherein the mixed metal mud is used as a smelting raw material for subsequent metal recovery treatment.

Description

Green stripping solution for photovoltaic solder strip and valuable metal separation and recovery method Technical Field The invention relates to the field of recovery of crystalline silicon photovoltaic modules, in particular to a method for separating and recovering green deplating liquid and valuable metals for photovoltaic solder strips. Background Along with the rapid development of the photovoltaic industry, the installation scale of the photovoltaic module is continuously enlarged, and the photovoltaic module which is put into use in early stages gradually enters a concentrated retirement stage. The photovoltaic solder strip is used as an important material for electric connection of the battery pieces in the photovoltaic module, is usually a tin-coated copper strip, the inside of the photovoltaic solder strip is a copper matrix, the surface of the photovoltaic solder strip is covered with a tin-lead-based alloy coating, and part of the photovoltaic solder strip also contains noble metals such as silver. Therefore, how to efficiently and environmentally realize the recovery of valuable metals in the photovoltaic solder strip in the decommissioning process has important economic value and environmental significance. In the prior art, the recovery method for metals in the photovoltaic solder strip mainly comprises a high-temperature heat treatment method, a physical mechanical separation method and a chemical leaching method. The high-temperature heat treatment method has high energy consumption and high equipment requirement, is easy to cause metal oxidation loss, and is difficult to realize thorough separation of the plating metal and the copper matrix by a physical mechanical separation method, and the recovery purity and recovery rate of the metal are limited. Therefore, chemical leaching is attracting attention because of the relatively mild treatment conditions, but it still has many drawbacks in practical use. The Chinese patent application with publication number CN120866640A discloses a method for selectively recovering valuable metals by utilizing an acetic acid system to treat photovoltaic solder strips of retired crystalline silicon batteries, wherein lead is enabled to enter a solution through acetic acid leaching, and tin is oxidized and hydrolyzed to form tin dioxide precipitate in the reaction process, so that separation of tin, lead and copper is realized. However, the method essentially belongs to a recovery path for converting tin into solid phase precipitation, the reaction time is long, and a compact deposition layer is easy to form on the surface of the solder strip in the deplating process, so that the subsequent reaction is hindered, the deplating efficiency is low, and the technological process is relatively complex. In addition, the method has limited adaptability to silver-containing solder strips, and is difficult to effectively solve the problems of stable dissolution and recovery of silver in a system, and Chinese patent application with publication number of CN119433222A discloses a metal recovery method for treating the photovoltaic solder strips by adopting a strong acid or strong oxidation system, which relies on strong oxidation capability to realize rapid dissolution of plating metal of the solder strips, and is in favor of green and sustainable industrial application because the method has high reaction speed, but easily causes obvious corrosion to copper matrixes in actual operation, so that part of copper enters a solution, the recovery quality of copper is reduced, the difficulty of separating various metals in subsequent solutions is increased, and meanwhile, the use of strong acid or strong oxidant increases the safety risk and environmental burden. In addition, when a silver-containing photovoltaic solder strip is treated, the existing chemical leaching system generally lacks an effective dissolution and stability control means for silver, and under a chlorine-containing environment or unsuitable reaction conditions, silver is easy to precipitate in a silver chloride or metallic silver form and is adhered to the surface of the solder strip or deposited in the reaction system, so that not only is the silver resource lost, but also the problems of blackening of the surface of the solder strip and the like are caused, and the stripping effect and the subsequent metal recovery process are further influenced. In summary, the existing photovoltaic solder strip stripping and valuable metal recovery technology still has obvious defects in the aspects of stripping efficiency, copper matrix protection, silver-containing solder strip treatment, environmental friendliness and the like, and the comprehensive requirements of rapid stripping, high-value metal recovery and environmental protection are difficult to meet. Disclosure of Invention One of the technical problems to be solved by the invention is to provide a green stripping solution for a photovoltaic solder strip,