Photovoltaic module metal material recovery process based on low-temperature green chemical treatment

Abstract

The invention provides a photovoltaic module metal material recovery process based on low-temperature green chemical treatment. According to the technology, a low-toxicity green chemical solvent is used, metal materials (such as silver and copper) in the waste photovoltaic module are dissolved, separated and reduced under the low-temperature condition, high-purity metal is recycled, and energy consumption and environmental pollution are effectively reduced. The method comprises the following steps: immersing a metal part of the waste photovoltaic module into a green chemical solvent, dissolving the metal at low temperature, and extracting the metal through filtration and reduction reaction; the recycled metal is high in purity and high in recycling rate, and meanwhile silicon wafers and glass parts can be effectively treated through physical and chemical methods. The technology has the advantages of high metal recovery efficiency, low environmental influence and low energy consumption, and is suitable for recovery treatment of waste photovoltaic modules.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic module recycling, and more specifically to a photovoltaic module metal material recycling process based on low-temperature green chemical treatment. Background Art

[0002] With the rapid development of the photovoltaic industry, the problem of handling waste photovoltaic modules has become increasingly prominent. Waste photovoltaic modules contain a variety of metal materials, including silver, aluminum, copper, etc. These metals are not only valuable resources, but also cause potential pollution to the environment. Therefore, how to recycle these metal materials efficiently and environmentally friendly has become a hot topic in the current photovoltaic industry recycling technology research.

[0003] The existing photovoltaic module recycling process mainly adopts high-temperature smelting or chemical dissolution, but these methods have the problems of high energy consumption and serious pollution during the treatment process. In order to solve these problems, the metal recovery process based on low-temperature green chemical treatment has gradually become a technical route that has attracted much attention. This process can not only extract metals efficiently at a lower temperature, but also reduce carbon dioxide emissions and the generation of other harmful substances in traditional recycling methods.

[0004] Therefore, the present invention provides a photovoltaic module metal material recycling process based on low-temperature green chemical processing, which aims to effectively recover metal materials in photovoltaic modules through low-temperature green chemical reactions while avoiding the defects of traditional recycling methods. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a photovoltaic module metal material recovery process based on low-temperature green chemical treatment. Through the action of low-temperature green solvents, the metal materials in photovoltaic modules can be effectively separated and recovered. The operation is simple, the energy efficiency is high, and the pollution to the environment is reduced.

[0006] To achieve the above object, the present invention provides the following technical solutions, which mainly include:

[0007] 1. A photovoltaic module metal material recycling process based on low-temperature green chemical treatment, characterized in that it includes the following steps:

[0008] (1) Component disassembly: Cut the waste photovoltaic components into small pieces through mechanical cutting and perform layer processing to separate the metal frame and glass layer;

[0009] (2) Soaking in green solvent: Soak the decomposed composite structure sheet in a low concentration green solvent. Under controlled temperature and time conditions, the metal material is dissolved by the reaction between the solvent and the metal material. The mathematical formula of the dissolution reaction is expressed as:

[0010] M+nS→M(S) n ;

[0011] Among them, M represents metal materials, S represents acid ions in green solvents, and M(S) n It is a metal complex;

[0012] (3) Metal complex extraction: extracting the dissolved metal complex by solid-liquid separation, precipitation, filtration, etc., and obtaining pure metal powder by electrochemical reduction;

[0013] (4) Silicon wafer cleaning and purification: The remaining silicon wafer is pickled, impurities are removed, and cleaned, and microscopic defects are removed by heat treatment or plasma etching. The formula for the pickling step is expressed as:

[0014] SiO 2 +2H + →Si 2+ +H 2 O;

[0015] Among them, SiO 2 is the impurity on the silicon wafer surface, H + is the hydrogen ion in the acid solution, Si 2+ for dissolved silicon ions;

[0016] (5) Solvent recovery: Use low-temperature evaporation and membrane separation technology to recover green solvents for reuse.

[0017] Preferably, the green solvent is a citric acid solution or an acetic acid solution with a concentration of 5%-15%.

[0018] Preferably, the soaking temperature is controlled between 30°C and 60°C, and the soaking time is 2-4 hours.

[0019] Preferably, the electrochemical reduction voltage is 0.5-2.0V.

[0020] Preferably, the concentration of the silicon wafer cleaning acid is 1%-5%.

[0021] Preferably, the recovered green solvent is separated from water and impurities by a low-temperature evaporation device and further purified by a membrane separation device.

[0022] Preferably, the metal material includes silver, aluminum and copper, and the metal complex is obtained by complexing the acid ions in the green solvent with the metal ions.

[0023] Preferably, the electrochemical reduction step comprises placing the metal complex in an electrolytic cell to obtain pure metal by electrolytic reduction reaction, and the electrochemical reduction reaction is expressed as:

[0024] M(S) n +ne - →M+nS;

[0025] Among them, M(S) n For metal complexes, e - is electron and M is metal.

[0026] Preferably, the silicon wafer purification step includes cleaning with a dilute acid solution to remove residual adhesive film, and removing organic impurities by low-temperature heat treatment.

[0027] Preferably, the extraction process of the metal material is carried out under low temperature conditions to reduce energy consumption and environmental impact.

[0028] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) Low temperature and high efficiency: Low temperature green chemical treatment greatly reduces the energy consumption in the high temperature smelting process, while avoiding the emission of harmful gases that may be generated at high temperatures;

[0030] (2) Green and environmentally friendly: The use of environmentally friendly solvents can avoid pollutants generated by traditional metal recovery methods and meet green and environmental protection requirements;

[0031] (3) High metal recovery rate: This method can efficiently dissolve metal materials in photovoltaic modules, especially precious metals such as silver, aluminum and copper, and has a good recovery effect;

[0032] (4) Simplified process: The operation process is simple, and the metal can be directly reduced to pure metal through electrochemical reduction reaction, avoiding the complicated extraction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example

[0037] The following is an example of a photovoltaic module metal material recycling process based on low-temperature green chemical treatment. Through this example, it is detailed how to use a low-temperature green chemical treatment method to efficiently recycle metal materials in discarded photovoltaic modules.

[0038] Materials preparation:

[0039] Waste photovoltaic modules: The metal parts of waste photovoltaic modules, including metal materials such as silver and copper, silicon wafers and glass layers.

[0040] Green chemical solvent: In this embodiment, a low-toxic, low-corrosive green chemical solvent is used as the recovery medium, and ammonium chloride solution (NH 4 Cl) and acetic acid (CH 3 COOH) mixed solution.

[0041] Equipment: including immersion tank, stirring device, separation device, heating device and filter.

[0042] Process steps (such as Figure 1 shown):

[0043] 1. Pretreatment of discarded photovoltaic modules:

[0044] The discarded photovoltaic modules are first cut and disassembled to remove most of the glass layers and silicon wafers, leaving the metal parts, including silver and copper wires, contacts, etc.

[0045] The metal parts of the processed photovoltaic modules will be sent to the chemical dissolution tank for subsequent recycling.

[0046] 2. Low temperature green chemical dissolution:

[0047] The metal part of the discarded photovoltaic module is immersed in a mixed solution of ammonium chloride and acetic acid. The concentration of the solution is 10% (w / v) ammonium chloride and 5% (v / v) acetic acid, and the temperature of the solution is set to 50°C.

[0048] At low temperatures, the metal part will react with the chemical solution, and metal materials such as silver and copper will be dissolved into the solution to form soluble metal salts. The reaction formula during the dissolution process is:

[0049] For copper (Cu): Cu+2NH 4 Cl→CuCl 2 +2NH 3

[0050] For silver (Ag): Ag+NH 4 Cl→AgCl+NH 3

[0051] During the reaction, a stirring device is used to ensure that the solution is uniform to improve the dissolution efficiency of the metal.

[0052] 3. Separation of metal ions:

[0053] During the metal dissolution process, silver and copper ions appear in the solution. At this time, solution filtration equipment is used to separate the dissolved metal ions from other undissolved substances (such as silicon chip debris and glass fragments) through the filter.

[0054] After filtering through the filter, the dissolved liquid portion (including dissolved metal ions) is sent to a recovery device for further purification.

[0055] 4. Metal salt precipitation and purification:

[0056] By adding an appropriate amount of reducing agent (such as hydrogen gas or sodium hydroxide solution) to the filtered solution, the dissolved metal ions (such as copper, silver, etc.) can be reduced and precipitated to form a metallic state.

[0057] An example of a reduction reaction is as follows:

[0058] For copper ions (Cu 2+ ):Cu 2+ +2e - →Cu

[0059] For silver ions (Ag + ): Ag + +e - →Ag

[0060] After the precipitated metal is filtered and washed to remove excess chemical reagents, the resulting pure metal can be used for further processing and application.

[0061] 5. Processing of silicon wafers and glass:

[0062] The silicon wafers and glass parts that cannot be dissolved are processed by physical crushing. Silicon wafers and glass can be refined by mechanical crushing, grinding and other methods.

[0063] The glass fragments are separated by a vibrating screen to select the purer glass materials for subsequent reuse. The broken silicon wafers can be further treated chemically or physically to recover their residual metal components.

[0064] 6. Residual waste liquid treatment:

[0065] After the metal dissolution and reduction reaction, the remaining solution contains a variety of metal impurities and chemical reagents. This waste liquid needs to be treated by chemical neutralization methods to ensure that it does not pollute the environment.

[0066] The acidic substances in the solution can be neutralized by adding lime (CaO), or harmful substances in the solution can be removed by using adsorption materials (such as activated carbon). The treated wastewater can be safely discharged or recycled.

[0067] Implementation results:

[0068] Metal recovery rate: This embodiment achieves efficient recovery of metal parts (such as silver and copper) of photovoltaic modules through low-temperature green chemical treatment. The recovery rate of silver can reach more than 95%, and the recovery rate of copper can reach more than 90%, which is much higher than traditional physical treatment and high-temperature smelting methods.

[0069] Metal purity: After reduction, the recovered metals have a high purity, with the purity of silver and copper reaching over 99% and 98% respectively, making them suitable for reprocessing and secondary utilization.

[0070] Environmental friendliness: Due to the use of green chemical reagents and low-temperature treatment methods, this process significantly reduces the emission of harmful gases and environmental pollution, and meets current environmental protection requirements.

[0071] Economic benefits: Through this low-temperature green chemical recycling process, the recovery and reuse of metal resources effectively reduces production costs while increasing the economic value of discarded photovoltaic modules.

[0072] This example demonstrates an efficient low-temperature green chemical treatment method for recycling metal materials in photovoltaic modules. This process can not only improve the metal recovery rate and purity, but also effectively reduce energy consumption and environmental pollution, with significant environmental and economic benefits.

[0073] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0074] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photovoltaic module metal material recycling process based on low-temperature green chemical treatment, characterized in that: The following steps are involved: (1) Component disassembly: Cut the waste photovoltaic components into small pieces through mechanical cutting and perform layer processing to separate the metal frame and glass layer; (2) Soaking in green solvent: Soak the decomposed composite structure sheet in a low concentration green solvent. Under controlled temperature and time conditions, the metal material is dissolved by the reaction between the solvent and the metal material. The mathematical formula of the dissolution reaction is expressed as: M+nS→M(S) n ; Among them, M represents metal materials, S represents acid ions in green solvents, and M(S) n It is a metal complex; (3) Metal complex extraction: extracting the dissolved metal complex by solid-liquid separation, precipitation, filtration, etc., and obtaining pure metal powder by electrochemical reduction; (4) Silicon wafer cleaning and purification: The remaining silicon wafer is pickled, impurities are removed, and cleaned, and microscopic defects are removed by heat treatment or plasma etching. The formula for the pickling step is expressed as: <h2 style=";text-align:left;direction:ltr">SiO2+2H<h2 style=";text-align:left;direction:ltr"> + <h2 style=";text-align:left;direction:ltr"> →Si<h2 style=";text-align:left;direction:ltr"> 2+ <h2 style=";text-align:left;direction:ltr"> +H2O; Among them, SiO2 is the impurity on the surface of silicon wafer, H + is the hydrogen ion in the acid solution, Si 2+ for dissolved silicon ions; (5) Solvent recovery: Use low-temperature evaporation and membrane separation technology to recover green solvents for reuse.

2. The recycling process according to claim 1, characterized in that: The green solvent is a citric acid solution or an acetic acid solution with a concentration of 5%-15%.

3. The recycling process according to claim 1, characterized in that: The soaking temperature is controlled between 30° C. and 60° C., and the soaking time is 2 to 4 hours.

4. The recycling process according to claim 1, characterized in that: The electrochemical reduction voltage is 0.5-2.0V.

5. The recycling process according to claim 1, characterized in that: The concentration of the silicon wafer cleaning acid is 1%-5%.

6. The recycling process according to claim 1, characterized in that: The recovered green solvent is separated from water and impurities by a low-temperature evaporation device and further purified by a membrane separation device.

7. The recycling process according to claim 1, characterized in that: The metal material comprises silver, aluminum and copper, and a metal complex is obtained by complexing acid radical ions in a green solvent with metal ions.

8. The recycling process according to claim 1, characterized in that: The electrochemical reduction step includes placing the metal complex in an electrolytic cell to obtain pure metal through an electrolytic reduction reaction. The electrochemical reduction reaction is expressed as follows: M(S) n +ne - →M+nS; Among them, M(S) n For metal complexes, e - is electron and M is metal.

9. The recycling process according to claim 1, characterized in that: The silicon wafer purification step includes cleaning with a dilute acid solution to remove residual adhesive film and removing organic impurities through low-temperature heat treatment.

10. The recycling process according to claim 1, characterized in that: The extraction process of the metal material is carried out under low temperature conditions to reduce energy consumption and environmental impact.

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