A resource recycling treatment method for waste and old crystalline silicon photovoltaic panel cell pieces

Abstract

The present application belongs to the technical field of rare and precious metal recovery, and particularly relates to a rare and precious metal recovery method for waste crystalline silicon photovoltaic panel cell pieces. The target resources for recovery include indium and / or gallium and / or tellurium and / or silver and / or silicon; the method comprises: 1) pre-treating the cell pieces to obtain cell sand; 2) separating an anode chamber and a cathode chamber by filter cloth, using an inert non-metal electrode as an anode in the anode chamber and an inert metal electrode as a cathode in the cathode chamber, using an acidic sodium chloride aqueous solution as an electrolyte, placing the cell sand in the anode chamber for electrolysis treatment, and depositing the target resources on the surface of the inert metal electrode to realize recovery after the electrolysis treatment is completed. The present application can realize the oxidation leaching and cathode reduction of the target resources by precise control, thereby realizing the efficient recovery of the target resources, and the overall recovery process has low difficulty, low cost and easy industrialization practice, and the purity of the reduction product is high, and a large amount of industrial pollution is not generated, and the present application has the advantages of green environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of solid waste recycling technology, and in particular relates to a resource recycling and processing method for waste crystalline silicon photovoltaic cells. Background Technology

[0002] Photovoltaic modules typically have a designed lifespan of 20 to 30 years, and as their service life nears its end, a large-scale decommissioning wave will occur. Improper disposal of such a massive amount of solid waste will result in serious resource waste and environmental pollution risks; conversely, if its efficient and clean recycling can be achieved, it can become an important supplementary source of strategic resources such as aluminum, silicon, silver, gallium, indium, and tellurium, which is of great significance for ensuring resource security and promoting the closed-loop development of the photovoltaic industry.

[0003] Currently, commercial photovoltaic modules are mainly divided into two categories: crystalline silicon and thin-film. Crystalline silicon modules are technologically mature and account for approximately 95% of the market share. Thin-film modules (mainly including copper indium gallium selenide (CIGS), cadmium telluride (CdTe), and gallium arsenide (GaAs) account for about 5%. Although their market share is smaller, they have extremely high resource recycling value due to their high content of key rare and dispersed metals such as gallium, indium, and tellurium. Both crystalline silicon and thin-film modules belong to the laminated encapsulation structure of "glass-EVA-cell layer-backsheet". Current recycling processes typically include: dismantling (removing the aluminum frame and junction box), separation (separating the laminated components), and deep resource recovery of valuable components. Dismantling technology is relatively mature; the separation stage mostly relies on pyrolysis or organic solvents to dissolve the EVA film, but this presents problems such as high energy consumption or the generation of organic waste gas / wastewater. The most challenging and economically valuable key lies in the third step—especially the efficient extraction and purification of important strategic resources such as gallium, indium, tellurium, silver, and silicon.

[0004] Existing recycling technologies for these important resources are mainly based on hydrochemical processes. The core of these processes is to transfer the target component to the liquid phase through acid leaching or oxidative leaching, followed by recovery through chemical precipitation, solvent extraction, or electrochemical deposition. For example, for silver in crystalline silicon solar cells, the mainstream process uses a nitric acid or hydrochloric acid-oxidant system for leaching, followed by chlorination precipitation or electrodeposition for recovery. For gallium and indium in thin-film solar cells, a complex process of high-temperature calcination-acid leaching-extraction separation is often employed. However, these methods generally suffer from the following prominent problems:

[0005] High reagent consumption and heavy pollution: The extensive use of strong acids, strong oxidants and organic extractants leads to the generation of high-salinity and highly toxic waste liquids / residues, resulting in high subsequent treatment costs and a poor environmental footprint.

[0006] The process is lengthy and has poor selectivity: the multi-step separation and purification process is not only energy-intensive, but also has serious interference between metals (such as silver and copper, indium and gallium), making it difficult to achieve high-selectivity recovery. The purity of the product often depends on subsequent refining.

[0007] The resource cycle is not closed: most processes are "consumption-based" reactions, and the media cannot be recycled, which contradicts the principles of green and low-carbon development.

[0008] Economic limitations: For retired battery materials with low grade and multiple metals, the recycling efficiency and economic benefits of traditional processes are insufficient when facing large-scale retirement scenarios.

[0009] Therefore, there is an urgent need to develop a clean, efficient, highly selective, and recyclable recycling technology. Ideally, the technology should be able to precisely target valuable components such as gallium, indium, tellurium, silver, and silicon under mild conditions, minimizing chemical input and secondary pollution, while achieving high purity and high direct recovery rates of the recycled products. This would provide a feasible path for the resource utilization of retired photovoltaic modules that combines environmental and economic benefits. Against this backdrop, this invention aims to construct a new green method through an electrochemical synergistic mechanism that can directly process broken battery materials and achieve sequential or selective recycling of multiple components. Summary of the Invention

[0010] To address the shortcomings of existing resource recycling methods for retired photovoltaic modules, especially solar cells, which are too simplistic, inefficient, ineffective, costly, and environmentally polluting, this invention provides a resource recycling method for waste crystalline silicon photovoltaic panels and solar cells.

[0011] The main objective of this invention is:

[0012] I. Significantly improve recovery efficiency and increase the purity of recovered products;

[0013] Second, reduce recycling costs and control environmental pollution caused by the recycling process.

[0014] To achieve the above objectives, the present invention adopts the following technical solution.

[0015] A method for recycling and processing waste crystalline silicon photovoltaic panels.

[0016] The target resources to be recovered include indium and / or gallium and / or tellurium and / or silver and / or silicon;

[0017] The method includes:

[0018] 1) The battery cells are crushed to obtain battery sand;

[0019] 2) Construct an electrolytic recovery system, with a filter cloth separating the anode chamber and the cathode chamber. The anode chamber uses an inert non-metallic electrode as the anode, and the cathode chamber uses an inert metal electrode as the cathode. An acidic sodium chloride aqueous solution is used as the electrolyte. Battery sand is placed in the anode chamber for electrolytic treatment. After the electrolytic treatment is completed, the target resource is deposited on the surface of the inert metal electrode to achieve recovery.

[0020] As a preferred option

[0021] Step 1) The solar cell is a polycrystalline silicon solar cell, a monocrystalline silicon single-sided solar cell, or a monocrystalline silicon double-sided solar cell;

[0022] Step 1) The battery sand has a particle size ≤ 300 μm and is separated from the anode.

[0023] As a preferred option

[0024] Step 2) The inert non-metallic electrode is a graphite electrode;

[0025] Step 2) The inert metal electrode is a titanium electrode.

[0026] As a preferred option

[0027] Step 2) The concentration of sodium chloride in the acidic sodium chloride aqueous solution is 15-25 wt%, and the pH value is ≤2.

[0028] As a preferred option

[0029] Step 2) The solid-liquid ratio of the battery sand and electrolyte is 1 g: (8-10) mL.

[0030] As a preferred option

[0031] Step 2) The electrolysis treatment is carried out at 50–60 °C, and the current density is controlled at 10.0–12.5 mA / cm² during the electrolysis treatment. 2 Electrolysis treatment time ≥ 2 h.

[0032] This invention relates to an electrolytic method for recovering resources (especially rare and precious metals, particularly silver) from waste crystalline silicon photovoltaic cells. However, this method clearly possesses broad applicability, showing great promise for use with non-metallic materials such as silicon (quasi-metallic materials), as well as rare metals such as gallium, indium, and tellurium. Taking silver as an example, the core lies in achieving efficient and highly selective recovery of silver through a closed-loop cycle of electrochemical oxidation-complexation-deposition, while generating almost no pollutant emissions. Specifically, this invention provides a process for recovering the rare and precious metal silver from decommissioned photovoltaic module cells using sodium chloride solution as both the leaching solution and the electrolyte through electrochemical leaching and deposition. This technical method mainly achieves resource recovery of rare and precious metals from decommissioned photovoltaic module cells through simultaneous electrochemical oxidation leaching and deposition. Its main principle involves using a diaphragm electrolytic cell, with sodium chloride solution as the electrolyte, and utilizing electrochemical action under acidic conditions to electrolyze Cl in the anolyte region. - The generated Cl2 and the further generated hypochlorite ions (ClO) -The process involves oxidizing and leaching the rare and precious silver from the decommissioned photovoltaic module cells, and then reducing the deposited elemental silver on the cathode plate through electrochemical deposition, thereby achieving resource recovery of rare and precious metals.

[0033] Specifically, the electrolysis system of this invention mainly includes the following three aspects:

[0034] Anode Chamber and Anode: The battery sand is placed in the anode chamber. Graphite or other inert non-metallic electrodes that do not participate in the reaction are selected as the anode because graphite and other inert non-metallic electrodes that do not participate in the reaction have good conductivity and high electrochemical stability (corrosion resistance) in the chloride system. The anode chamber is the main site where the silver leaching reaction occurs.

[0035] Cathode Chamber and Cathode: Silver deposition occurs in the cathode chamber. Titanium plates or other inert metal electrodes that do not participate in the reaction are selected as cathodes, mainly because they are chemically stable, not easily corroded, and the silver layer electrodeposited on their surface is easy to peel off and recover, while also having good conductivity.

[0036] The diaphragm plays a crucial role. First, it physically isolates the solid battery sand in the anode chamber, preventing it from entering the cathode chamber and contaminating the final metallic silver product. Second, it allows ions in the electrolyte (such as Na+) to pass through. + , Cl - H + (And silver complex ions) can pass freely, thus forming a complete ionic circuit and ensuring the continuous progress of the electrolysis reaction.

[0037] The overall reaction process can be viewed as the following steps:

[0038] Initial reaction (formation of active oxidant):

[0039]

[0040] The above-mentioned initial reaction occurs in the anode chamber, first forming active oxidants (Cl2 and / or ClO) for leaching silver and initiating subsequent reactions. - );

[0041] Silver leaching reaction: ,

[0042] The above-mentioned silver leaching reaction can effectively leach and dissolve the rare and precious metal silver in battery cells, which is difficult to separate and extract, to form silver ions. Then comes the key process of this invention, namely, how to maintain the effective stability of silver ions and avoid the precipitation of silver ions as silver chloride—complexation reaction:

[0043] ;

[0044] This complexation process is crucial. Without a high concentration of Cl... - Existence, generated Ag + Will quickly with Cl - The combination forms a sparingly soluble silver chloride (AgCl) precipitate, which covers the surface of the battery sand and forms a "passivation layer," thereby hindering the subsequent reaction. Therefore, the high-concentration NaCl electrolyte is not only a conductive medium, but also a key complexing agent for achieving continuous silver dissolution. The entire anodic leaching process can be regarded as an electrochemical process that generates an oxidant (Cl2) and is driven by this oxidant to achieve chemical dissolution. The dissolution products are kept in the solution through complexation.

[0045] Terminal reaction (silver deposition):

[0046] ;

[0047] This creates a redox reaction cycle for rare and precious metals, using chloride ions as the "reaction medium" for conduction, achieving non-contact oxidative leaching of silver from battery sand. This process effectively avoids excessive and disordered dissolution caused by directly using battery cells as the anode, which leads to the oxidation and dissolution of excessive impurities. It also effectively controls the form of silver complex ions to prevent precipitation, and the cathode reduces the silver complex ions. Chloride ions are oxidized to active species at the anode and released at the cathode, theoretically resulting in no net consumption. The choice of active oxidant is crucial in this process; an overly strong oxidant will cause more inert components to be oxidized and reduced earlier at the cathode, leading to impurity formation. Therefore, this invention uses a stable, inexpensive, and readily available acidic sodium chloride aqueous solution as the medium for non-contact conduction oxidation, achieving just the right oxidizing power for metallic silver while ensuring preferential silver deposition, thus ensuring reaction efficiency and silver purity. At the end of the cycle, the electrolyte returns to its original state, theoretically producing no pollutants, and in practical operation, producing almost no harmful pollutants such as chlorine gas. The entire process is green and environmentally friendly, and both the oxidation and reduction targets can be effectively and accurately directed towards the rare and precious metal silver.

[0048] Compared with traditional pyrometallurgical and hydrometallurgical recycling methods, this invention has advantages in energy consumption, does not produce toxic gases (such as dioxins) or polluting waste residue, and does not cause secondary pollution to the environment or harmful effects on operator health. Furthermore, the technical solution of this invention has potential for expansion into new technical fields. Applications adapted to this invention should not be limited to the recovery of rare and precious metals (rare and precious metals) from waste battery cells, but can also be used for the recovery of rare and precious metals from similar waste materials. Moreover, it can be more broadly applied to the comprehensive resource recovery of most solid wastes, achievable by simply changing some operating parameters.

[0049] The beneficial effects of this invention are:

[0050] This invention enables precise control of oxidation leaching and cathodic reduction of target resources, thereby achieving efficient recovery of target resources. The overall recovery process is simple, low-cost, and easy to industrialize. Moreover, the reduction product has high purity and does not generate a large amount of industrial pollution, thus having the advantages of being green and environmentally friendly. Attached Figure Description

[0051] Figure 1 The leaching rate and deposition rate of silver under different current density conditions in Example 1;

[0052] Figure 2 The leaching rate and deposition rate of silver under different electrolysis time conditions in Example 2;

[0053] Figure 3 The leaching rate and deposition rate of silver under different solid-liquid ratios in Example 3;

[0054] Figure 4 The leaching rate and deposition rate of silver under different electrolysis temperatures in Example 4;

[0055] Figure 5 The leaching rate and deposition rate of silver under different battery sand particle sizes in Example 5;

[0056] Figure 6 The leaching rate and deposition rate of silver were determined under different sodium chloride concentrations in the electrolytes in Example 6.

[0057] Figure 7 The image shows the EDS characterization spectrum of the cathode titanium plate recovered from experimental group A in Example 7.

[0058] Figure 8 The leaching rate and deposition rate of silver are obtained when the battery sand obtained from different types of crystalline silicon solar cells in Example 8 is used as raw material. Detailed Implementation

[0059] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0060] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0061] Unless otherwise specified, the battery cells used in this invention (processed starting from the original battery laminate) all undergo the following treatment to obtain battery sand:

[0062] After the battery laminate is pyrolyzed at 500 °C for 30 minutes, glass, solder ribbon, and battery cells are separated to obtain battery cells. The battery cells are then cleaned, crushed, and sieved to obtain materials with different target particle sizes. During sieving, the material is first passed through a 300 μm sieve to separate battery sand with a particle size >300 μm. Subsequently, it is passed through a 150 μm sieve and a 100 μm sieve to obtain battery sand with particle sizes of 150–300 μm, 100–150 μm, and <100 μm, respectively.

[0063] Unless otherwise specified, the electrode area of ​​both the graphite anode and the titanium cathode used in this invention is 4 cm². 2 Unless otherwise specified, the electrolytic recovery system in this embodiment of the invention is divided into an anode chamber and a cathode chamber by a filter cloth. The anode chamber uses a graphite anode as the anode, and the cathode chamber uses a titanium cathode as the cathode. Battery sand is added to the anode chamber, and the battery sand is added without direct contact with the anode. However, the recycled waste battery sand does not have good conductivity, so direct contact will not affect the core reaction process of the technical solution of this invention.

[0064] Unless otherwise specified, the silver leaching rate and silver deposition rate are calculated using the following formulas.

[0065]

[0066]

[0067] Unless otherwise specified, the battery sand used in the embodiments of this invention is mixed battery sand with a particle size ≤300 μm, that is, battery sand remaining after being filtered and separated to remove battery sand with a particle size >300 μm through a 300 μm sieve for the first time. Furthermore, in the formula: electrolytic slag refers to the solid residue remaining in the anode chamber after electrolysis. Example 1

[0068] A method for recycling and processing waste crystalline silicon photovoltaic cells, wherein the target resource to be recycled in this example is silver, is as follows:

[0069] The electrolyte concentration was controlled at 20 wt% NaCl, pH was adjusted to 1 with hydrochloric acid, 10 g of battery sand was added, the liquid-to-solid ratio was 10 mL:1 g, the temperature was 50 ℃, and electrolysis was carried out for 3 h. The current density was varied to 7.5 mA / cm². 2 10 mA / cm 212.5 mA / cm 2 15 mA / cm 2 To investigate the effect of current density on silver leaching and deposition.

[0070] The leaching rate and deposition rate of silver under different current densities are as follows: Figure 1 As shown. The current density is 10 mA / cm². 2 At this point, the leaching and deposition rates were highest, reaching 98.58% and 92.79%, respectively. Therefore, the value of 10 mA / cm² can be determined. 2 The optimal current density is achieved.

[0071] As can be seen from the figure, when the current density is 10.0–12.5 mA / cm² 2 Good separation and recovery of metallic silver can be achieved at all times. When the current density is too low, the anode contains Cl2 and / or ClO. - The slow formation rate leads to low silver leaching efficiency, insufficient cathode electron supply, and slow deposition rate. Theoretically, extending the electrolysis time can improve this defect, but industrial efficiency and cost-effectiveness will decrease significantly, and other side reactions may occur due to the mismatch between the cathode and anode reaction rates. Furthermore, when the current density is too high, the reaction rate is affected by mass transfer steps (such as Cl...). - The diffusion of silver complex ions to the anode and to the cathode is limited. Excessively high current density can lead to severe concentration polarization on the electrode surface. At the cathode, due to the untimely replenishment of silver complex ions, the electrode potential becomes more negative, thereby exacerbating the hydrogen evolution side reaction, resulting in a decrease in current efficiency and apparent deposition rate, and ultimately a significant decrease in both leaching rate and deposition rate.

[0072] Therefore, for the technical solution of this invention, it is necessary to effectively control the current density to be between 10.0 and 12.5 mA / cm². 2 This is to ensure high reaction efficiency and optimal reaction results. Example 2

[0073] A method for recycling and processing waste crystalline silicon photovoltaic cells, wherein the target resource to be recycled in this example is silver, is as follows:

[0074] The electrolyte concentration was controlled at 20 wt% NaCl, pH was adjusted to 1 with hydrochloric acid, 10 g of battery sand was added, the liquid-to-solid ratio was 10 mL:1 g, the temperature was 50 ℃, and the current density was 10 mA / cm². 2 Electrolysis times were varied to 1, 2, 3, and 4 h to investigate the effect of electrolysis time on silver leaching and deposition.

[0075] The leaching rate and deposition rate of silver under different electrolysis times are as follows: Figure 2As shown. At a current density of 10 mA / cm² 2 Under the given conditions, the silver leaching rate was above 98% for both 3 and 4 hours of electrolysis, with no significant difference. Therefore, 3 hours of electrolysis is the optimal time. However, for industrial-scale operations, 2 hours of electrolysis is usually sufficient to ensure good leaching and recovery results while maintaining high cost-effectiveness. Considering economic benefits and equipment turnover rate, 2–4 hours should be the optimal choice. Example 3

[0076] A method for recycling and processing waste crystalline silicon photovoltaic cells, wherein the target resource to be recycled in this example is silver, is as follows:

[0077] The electrolyte concentration was controlled at 20 wt% NaCl, pH was adjusted to 1 with hydrochloric acid, the temperature was 50 ℃, and the current density was 10 mA / cm². 2 Electrolysis time was 3 h. The amount of battery sand added was changed to adjust different liquid-solid ratios of 10 mL:1g, 8 mL:1g, 6 mL:1g, and 4 mL:1g to investigate the effect of liquid-solid ratio on silver leaching and deposition.

[0078] The leaching rate and deposition rate of silver under different liquid-solid ratios are as follows: Figure 3 As shown. At a current density of 10 mA / cm² 2 Under the premise of 3 hours of electrolysis, when the liquid-to-solid ratio is greater than 8 mL:1 g, the silver leaching rate of the battery sand is higher than 99%, and there is no significant difference. Therefore, considering the processing capacity, the optimal liquid-to-solid ratio is 8 mL:1 g. However, when the solid-to-liquid ratio is too low, the slurry becomes too viscous, the gaps between particles decrease, leading to the leaching of ions (such as Cl-)... - [AgCl] n ] (n-1)- Increased diffusion and mass transfer resistance in the liquid phase can prevent some particles from effectively contacting the electrolyte, thus reducing the leaching rate. Example 4

[0079] A method for recycling and processing waste crystalline silicon photovoltaic cells, wherein the target resource to be recycled in this example is silver, is as follows:

[0080] The electrolyte concentration was controlled at 20 wt% NaCl, pH was adjusted to 1 with hydrochloric acid, 10 g of battery sand was added, the liquid-to-solid ratio was 10 mL:1 g, and the current density was 10 mA / cm². 2 The electrolysis time was 3 h, and the electrolysis temperature was adjusted to 30 ℃, 40 ℃, 50 ℃ and 60 ℃ to investigate the effect of electrolysis temperature on silver leaching and deposition.

[0081] The leaching rate and deposition rate of silver under different temperature conditions are as follows: Figure 4As shown. At a NaCl concentration of 20 wt% and a current density of 10 mA / cm². 2 Under the conditions of 3 hours of electrolysis and a liquid-to-solid ratio of 8:1, the leaching and deposition rates were highest at 50°C, therefore 50°C is considered the optimal electrolysis temperature. This is mainly because, according to Arrhenius law, increasing the temperature accelerates the chemical reaction rate and ion diffusion rate, which is beneficial for improving the leaching and deposition efficiency of silver. However, excessively high temperatures (such as 60°C) will increase the evaporation of electrolyte raw material components (especially HCl and water), leading to changes in system concentration and pH value, and also significantly increasing energy consumption. In addition, the solubility of chlorine in water decreases with increasing temperature, adversely affecting the leaching process, and the loss of intermediate media prevents the reaction cycle from being effectively closed. Example 5

[0082] A method for recycling and processing waste crystalline silicon photovoltaic cells, wherein the target resource to be recycled in this example is silver, is as follows:

[0083] The electrolyte concentration was controlled at 20 wt% NaCl, pH was adjusted to 1 with hydrochloric acid, 10 g of battery sand was added, the liquid-to-solid ratio was 10 mL:1 g, the temperature was 50 ℃, and the current density was 10 mA / cm². 2 The electrolysis time was 3 h, and the effect of battery sand particle size on silver leaching and deposition was investigated by adding battery sand of different particle sizes.

[0084] Leaching and deposition rates of silver in battery sand under different particle size conditions, such as Figure 5 As shown, the leaching and deposition rates of silver continuously increase with decreasing particle size of the battery sand. When the particle size is less than 100 μm, the leaching and deposition rates reach 99.76% and 99.50%, respectively. Therefore, the optimal particle size can be considered to be less than 100 μm. However, for general industrial implementation, battery sand with a particle size ≤300 μm has a high industrial cost-effectiveness and can be effectively implemented. Example 6

[0085] A method for recycling and processing waste crystalline silicon photovoltaic cells, wherein the target resource to be recycled in this example is silver, is as follows:

[0086] The electrolyte was controlled with pH adjusted to 1 using hydrochloric acid, 10 g of battery sand was added, the liquid-to-solid ratio was 10 mL:1 g, the temperature was 50 ℃, and the current density was 10 mA / cm². 2 Electrolysis time was 3 h, and the NaCl concentration was changed to 10 wt%, 15 wt%, 20 wt%, and 25 wt% to investigate the effect of chloride concentration on the leaching rate and deposition rate of silver in the battery. The results are as follows: Figure 6 As shown.

[0087] Under these experimental conditions, when the sodium chloride concentration in the electrolyte was 15 wt%, the leaching rate and deposition rate of silver in the battery sand reached 98.78% and 97.98%, respectively. Increasing the NaCl concentration did not show a significant difference; therefore, the optimal NaCl concentration was considered to be 15 wt%. This is because at excessively low concentrations, the available Cl... - Not enough to include all Ag + The formation of soluble complex ions through complexation leads to AgCl precipitation, terminating the reaction. The reaction cycle cannot be effectively closed, resulting in significant loss of rare and precious metals, and AgCl will deposit and cover the surface of the battery sand, causing reaction termination. However, when the concentration is further increased, such as in the 20 wt% and 25 wt% experimental groups, a noticeable decrease in performance is observed, with no significant improvement in leaching rate and deposition rate, indicating that at 15 wt%, Cl... - Concentration is no longer the limiting step in the reaction. Continuing to increase the concentration not only wastes raw materials, but may also slightly reduce ion mobility due to the increased solution viscosity, thus limiting the reaction. Example 7

[0088] Based on Examples 1-6 above, the optimal parameters for the operation process of this invention have been largely determined. Furthermore, the electrolyte system is adjusted and improved to study the impact of different electrolyte systems on the technical effects of this invention. Specifically, in this example, equal amounts of hydrobromic acid and sodium bromide are used to replace hydrochloric acid and sodium chloride in the original Example 1, constructing the following two experimental groups:

[0089] Experimental Group A: The NaCl concentration in the electrolyte was controlled at 15 wt%, and the pH was adjusted to 1 with hydrochloric acid. 10 g of battery sand with a particle size <100 μm was added. The liquid-to-solid ratio was 10 mL:1 g. The temperature was 50 ℃, and the current density was 10 mA / cm². 2 Electrolysis time: 3 hours;

[0090] Experimental Group B: The NaBr concentration in the electrolyte was controlled at 15 wt%, and the pH was adjusted to 1 with hydrobromic acid. 10 g of battery sand with a particle size <100 μm was added. The liquid-to-solid ratio was 10 mL:1 g. The temperature was 50 ℃, and the current density was 10 mA / cm². 2 Electrolysis time: 3 hours.

[0091] In experimental group A, the recovered cathode titanium plate had a silvery-white surface, and its EDS spectrum was as follows: Figure 7As shown in the spectrum, a significant amount of rare and precious silver has been deposited with relatively high purity. However, the final recovered cathode titanium plate of experimental group B showed some yellow-red discoloration, indicating a large amount of copper mixed in the deposition. This suggests that the selection of the oxidant (and oxidant precursor) is particularly important in the technical solution of this invention. Using an excessively strong or weak oxidant (including oxidant precursor), or an oxidant that cannot effectively maintain the stability of silver ions, will ultimately lead to a significant decrease in the implementation effect.

[0092] This also demonstrates that by selecting and controlling the oxidant (and its precursors), targeted leaching, deposition, and recovery of different target resources can be achieved. This has extremely high scientific research and industrial value. As other experiments have shown, based on the method of this invention, by adjusting various parameters and materials, the leaching and deposition rates of silicon, gallium, indium, and tellurium can all reach the range of 60-70%. Although the effect is not as good as that of silver, it clearly has broad applicability. Example 8

[0093] As in Examples 1-7 above, the battery sand was obtained by grinding polycrystalline silicon solar cells. This example further adds monocrystalline silicon single-sided and double-sided solar cells as raw materials for processing and grinding to obtain battery sand of the same specifications. The same experiments were conducted to determine the silver recovery effect of this process on different types of crystalline silicon solar cells. The results are as follows: Figure 8 As shown.

[0094] The results showed that under this process, the silver leaching rate of the three different types of solar cells was higher than 99%, and the relative standard deviation was low. This indicates that the process is very effective in recovering the rare and precious metal silver from retired photovoltaic cells, and has high stability and extremely high industrial applicability.

Claims

1. A method for resource recycling and processing of waste crystalline silicon photovoltaic panels, characterized in that, The target resource to be recovered is silver; The method includes: 1) The battery cells are crushed to obtain battery sand; 2) Construct an electrolytic recovery system, with filter cloth separating the anode chamber and the cathode chamber. The anode chamber uses an inert non-metallic electrode as the anode, and the cathode chamber uses an inert metal electrode as the cathode. An acidic sodium chloride aqueous solution is used as the electrolyte. Battery sand is placed in the anode chamber for electrolytic treatment. After the electrolytic treatment is completed, the target resource is deposited on the surface of the inert metal electrode to achieve recovery. Step 1) The particle size of the battery sand is ≤300 μm; Step 2) The concentration of sodium chloride in the acidic sodium chloride aqueous solution is 15-25 wt%; Step 2) The solid-liquid ratio of the battery sand and electrolyte is 1 g: (8-10) mL; Step 2) The electrolysis treatment is carried out at 50–60 °C, and the current density is controlled at 10.0–12.5 mA / cm² during the electrolysis treatment. 2 Electrolysis treatment time ≥ 2 h.

2. The resource recycling and processing method for waste crystalline silicon photovoltaic panels according to claim 1, characterized in that, Step 1) The solar cell is a polycrystalline silicon solar cell, a monocrystalline silicon single-sided solar cell, or a monocrystalline silicon double-sided solar cell; Step 1) The battery sand is separated from the anode.

3. The resource recycling and processing method for waste crystalline silicon photovoltaic panels according to claim 1, characterized in that, Step 2) The inert non-metallic electrode is a graphite electrode; Step 2) The inert metal electrode is a titanium electrode.

4. The resource recycling and processing method for waste crystalline silicon photovoltaic panels according to claim 1, characterized in that, Step 2) The pH value of the acidic sodium chloride aqueous solution is ≤2.

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