Method for producing high-purity silver powder through photovoltaic panel battery piece

Abstract

The invention relates to the technical field of silver powder preparation, and provides a method for producing high-purity silver powder by utilizing a photovoltaic panel battery piece, which comprises the following steps: S1, taking a waste photovoltaic battery piece, and carrying out soaking pretreatment by adopting an acid solution to obtain a pretreated photovoltaic battery piece; s2, mixing the pretreated photovoltaic cell and an oxidizing agent, and filtering to obtain a reaction solution; s3, the reaction liquid is subjected to aftertreatment, and silver liquid is obtained; s4, sodium chloride is added into the silver liquid for precipitation, and silver chloride is obtained; s5, reducing the silver chloride to obtain silver powder; the oxidizing agent comprises hydrogen peroxide and an ammonium salt solution in a mass ratio of (5-10): 1. According to the technical scheme, the problem that the purity of the prepared silver powder is low when the high-purity silver powder is produced through a photovoltaic panel battery piece in the related technology is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of silver powder preparation, and specifically, to a method for producing high-purity silver powder using photovoltaic panel cells. Background Art

[0002] In the photovoltaic industry, silver powder, as the core conductive phase of photovoltaic silver paste, its purity plays a crucial role in the performance of photovoltaic cells. From the current production and supply status of photovoltaic silver powder, the silver powder produced using photovoltaic panel cells has the problem of relatively low purity, and there are various reasons for this problem.

[0003] Since the recycled photovoltaic panel cells have complex sources and may be mixed with various impurities, and the existing pretreatment means such as physical screening, air classification or flotation method are difficult to completely remove these impurities, resulting in the subsequent silver powder purity being affected. For example, if other metal oxides or organic impurities adhere to the surface of the cell, in the subsequent dissolution process, these impurities may enter the solution together with silver, increasing the separation difficulty; in the dissolution link, common leaching agents such as nitric acid, while dissolving silver powder, may also dissolve some impurity metals, increasing the types of impurities in the solution. Taking nitric acid as an example, when it dissolves silver powder, it may dissolve a small amount of metal impurities such as copper and iron contained in the cell, and these impurity ions are difficult to be completely separated from silver during the subsequent silver ion enrichment and reduction processes, thereby reducing the purity of silver powder.

[0004] Therefore, the silver powder recovered from waste photovoltaic cells still has the problem of relatively low purity and is difficult to meet the current situation of silver powder recycling and reuse. Summary of the Invention

[0005] The present invention provides a method for producing high-purity silver powder using photovoltaic panel cells, which solves the problem of relatively low purity of the prepared silver powder when producing high-purity silver powder using photovoltaic panel cells in the related art.

[0006] The technical solution of the present invention is as follows: The present invention provides a method for producing high-purity silver powder using photovoltaic panel cells, comprising the following steps: S1. Take waste photovoltaic cells and soak them with an acid solution for pretreatment to obtain pretreated photovoltaic cells; S2. Mix the pretreated photovoltaic cells and the oxidant, and filter to obtain a reaction solution; S3. Post-treat the reaction solution to obtain a silver solution; S4. Add sodium chloride precipitation to the silver solution to obtain silver chloride; S5. Reduce the silver chloride to obtain silver powder; The components of the oxidant include hydrogen peroxide and ammonium salt solution with a mass ratio of 5-10:1.

[0007] As a further technical solution, the concentration of the acid solution is 5-7 mol / L, for example, it can be 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L, 6.8 mol / L, 7 mol / L, and preferably 6 mol / L; The mass fraction of the hydrogen peroxide is 4 wt%-5 wt%; In the ammonium salt solution, the mass-volume ratio of the ammonium salt to water is 12-16 g:1 L, for example, it can be 12 g:1 L, 12.4 g:1 L, 12.8 g:1 L, 13.2 g:1 L, 13.4 g:1 L, 14 g:1 L, 15 g:1 L, 16 g:1 L, preferably 12 g:1 L, 15 g:1 L, 16 g:1 L, and more preferably 15 g:1 L.

[0008] As a further technical solution, the ammonium salt includes one or more of ammonium chromate, magnesium ammonium phosphate, and aluminum ammonium phosphate, and preferably ammonium chromate.

[0009] As a further technical solution, the acid solution includes one or more of hydrochloric acid solution, nitric acid solution, and sulfuric acid solution.

[0010] In the process of preparing silver powder from waste photovoltaic cell chips in the present invention, acid solution is used for soaking pretreatment, which has the functions of dissolving metals and separating matrix materials. Silver in the photovoltaic cell chips exists in the form of metal or compound. The acid solution can chemically react with silver and other metals, converting them into ionic state and entering the solution, promoting the detachment of silver from the structure of the cell chips. At the same time, during the use and recycling of waste photovoltaic cell chips, various organic and inorganic impurities will be adsorbed on the surface, such as dust, oil stains, and oxides generated due to environmental factors. The acid solution can react with these impurities, thereby cleaning the surface of the cell chips and achieving the effect of initially removing impurities, ensuring the purity of subsequent silver powder extraction.

[0011] As a further technical solution, the mass of sodium chloride is 5%-10% of the mass of the silver solution.

[0012] When preparing silver powder from waste photovoltaic cell chips, sodium chloride can react with silver ions in the solution to precipitate silver chloride, promoting the detachment of silver, providing favorable conditions for subsequent further extraction and purification of silver powder.

[0013] As a further technical solution, sodium gluconate is added before the post-treatment.

[0014] The glucoheptonate molecule contains multiple hydroxyl groups and carboxyl groups. When glucoheptonate is added to a solution system containing silver ions and other impurities (such as copper ions and iron ions), glucoheptonate reacts with copper ions and iron ions to form stable complexes. At the same time, glucoheptonate has a strong selectivity for copper ions and iron ions. In contrast, silver ions are difficult to undergo a similar complexation reaction with glucoheptonate and remain in the solution in ionic form, thus effectively separating silver ions from impurities such as copper ions and iron ions and improving the purity of silver powder.

[0015] As a further technical solution, the addition amount of the glucoheptonate is 0.5% - 1.5% of the mass of the reaction solution.

[0016] When the addition amount of glucoheptonate is 0.5% - 1.5% of the mass of the reaction solution, this addition amount can ensure that glucoheptonate fully complexes with impurity copper and iron ions, achieving a better removal effect and improving the purity of silver powder. At the same time, if the addition amount of glucoheptonate is greater than 1.5%, it will not only cause waste of raw materials, but also may increase the viscosity of the solution system, bringing inconvenience to subsequent separation operations such as precipitation and filtration, and affecting the quality of silver powder.

[0017] As a further technical solution, the temperature of the immersion pretreatment is 40 - 45 °C, and the time is 30 - 50 min.

[0018] As a further technical solution, the temperature of the mixing is 45 - 55 °C, and the time is 10 - 15 min.

[0019] As a further technical solution, iron powder is used for reduction treatment during reduction.

[0020] The working principle and beneficial effects of the present invention are as follows: In the present invention, waste photovoltaic cell chips are used as raw materials, realizing the reuse of waste resources. It not only effectively reduces the potential harm of photovoltaic industry waste to the environment and reduces the waste treatment cost, but also extracts silver powder with high economic value from waste resources; when preparing silver powder, hydrogen peroxide and ammonium salt solution are used as oxidants to react with the pretreated photovoltaic cell chips, effectively inhibiting the dissolution of impurities, greatly improving the purity of the finally obtained silver powder, and also increasing the yield of silver powder. High-purity silver powder has a broader application prospect in fields such as electronics and chemical industry, and can meet the production requirements of high-end products. Specific embodiments

[0021] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0022] Embodiment 1 A method for producing high-purity silver powder using photovoltaic cell sheets includes the following steps: S1. Take waste photovoltaic cell sheets and soak them in a 5 mol / L sulfuric acid solution at 40 °C for 50 min for pretreatment to obtain pretreated photovoltaic cell sheets; S2. Mix the pretreated photovoltaic cell sheets and an oxidant at 45 °C for 15 min, and filter to obtain a reaction solution; the components of the oxidant are hydrogen peroxide (mass fraction 4 wt%) and ammonium chromate solution with a mass ratio of 5:1; the mass-volume ratio of ammonium chromate to water in the ammonium chromate solution is 12 g:1 L; S3. Press-filter the reaction solution to remove the filter residue to obtain silver solution; S4. Add sodium chloride (the mass of sodium chloride is 5% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride; S5. Reduce the silver chloride with iron powder to obtain silver powder. The yield of the silver powder is 97.6%, the content of silver element in the silver powder is 99.99%, the content of Cu element is 0.0025%, and the content of Fe element is 0.0031%.

[0023] Embodiment 2 A method for producing high-purity silver powder using photovoltaic cell sheets includes the following steps: S1. Take waste photovoltaic cell sheets and soak them in a 7 mol / L sulfuric acid solution at 45 °C for 30 min for pretreatment to obtain pretreated photovoltaic cell sheets; S2. Mix the pretreated photovoltaic cell sheets and an oxidant at 55 °C for 10 min, and filter to obtain a reaction solution; the components of the oxidant are hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 10:1; the mass-volume ratio of ammonium chromate to water in the ammonium chromate solution is 16 g:1 L; S3. Press-filter the reaction solution to remove the filter residue to obtain silver solution; S4. Add sodium chloride (the mass of sodium chloride is 10% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride; S5. Reduce the silver chloride with iron powder to obtain silver powder. The yield of the silver powder is 97.3%, the content of silver element in the silver powder is 99.99%, the content of Cu element is 0.0024%, and the content of Fe element is 0.0033%.

[0024] Example 3 A method for producing high-purity silver powder using photovoltaic cell sheets includes the following steps: S1. Take waste photovoltaic cell sheets and soak them in a 6 mol / L sulfuric acid solution at 42 °C for 40 min for pre-treatment to obtain pre-treated photovoltaic cell sheets; S2. Mix the pre-treated photovoltaic cell sheets and an oxidant at 50 °C for 12 min, and filter to obtain a reaction solution; the components of the oxidant are hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 10:1; the mass-to-volume ratio of ammonium chromate to water in the ammonium chromate solution is 15 g:1 L; S3. Press-filter the reaction solution to remove the filter residue to obtain silver solution; S4. Add sodium chloride (the mass of sodium chloride is 8% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride; S5. Reduce the silver chloride with iron powder to obtain silver powder. The yield of the silver powder is 97.8%, the content of silver element in the silver powder is 99.99%, the content of Cu element is 0.0023%, and the content of Fe element is 0.0026%.

[0025] Example 4 A method for producing high-purity silver powder using photovoltaic cell sheets includes the following steps: S1. Take waste photovoltaic cell sheets and soak them in a 6 mol / L sulfuric acid solution at 42 °C for 40 min for pre-treatment to obtain pre-treated photovoltaic cell sheets; S2. Mix the pre-treated photovoltaic cell sheets and an oxidant at 50 °C for 12 min, and filter to obtain a reaction solution; the components of the oxidant are hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 5:1; the mass-to-volume ratio of ammonium chromate to water in the ammonium chromate solution is 15 g:1 L; S3. Press-filter the reaction solution to remove the filter residue to obtain silver solution; S4. Add sodium chloride (the mass of sodium chloride is 8% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride; S5. Reduce the silver chloride with iron powder to obtain silver powder. The yield of the silver powder is 97.0%, the content of silver element in the silver powder is 99.99%, the content of Cu element is 0.0027%, and the content of Fe element is 0.0030%.

[0026] Example 5 A method for producing high-purity silver powder using photovoltaic cell sheets includes the following steps: S1. Take waste photovoltaic cell sheets and soak them in a 6 mol / L sulfuric acid solution at 42 °C for 40 min for pre-treatment to obtain pre-treated photovoltaic cell sheets; S2. Mix the pretreated photovoltaic cells and the oxidant at 50 °C for 12 min, then filter to obtain the reaction solution. The oxidant consists of hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 7:1. The mass-to-volume ratio of ammonium chromate to water in the ammonium chromate solution is 15 g:1 L. S3. Press-filter the reaction solution to remove the filter residue and obtain the silver solution. S4. Add sodium chloride (the mass of sodium chloride is 8% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride. S5. Reduce the silver chloride with iron powder to obtain silver powder. The yield of the silver powder is 98.7%. The content of silver element in the silver powder is 99.99%, the content of Cu element is 0.0020%, and the content of Fe element is 0.0025%.

[0027] Example 6 A method for producing high-purity silver powder using photovoltaic cells includes the following steps: S1. Take waste photovoltaic cells and soak them in 6 mol / L sulfuric acid solution at 42 °C for 40 min for pretreatment to obtain pretreated photovoltaic cells. S2. Mix the pretreated photovoltaic cells and the oxidant at 50 °C for 12 min, then filter to obtain the reaction solution. The oxidant consists of hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 8:1. The mass-to-volume ratio of ammonium chromate to water in the ammonium chromate solution is 15 g:1 L. S3. Press-filter the reaction solution to remove the filter residue and obtain the silver solution. S4. Add sodium chloride (the mass of sodium chloride is 8% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride. S5. Reduce the silver chloride with iron powder to obtain silver powder. The yield of the silver powder is 99.3%. The content of silver element in the silver powder is 99.99%, the content of Cu element is 0.0018%, and the content of Fe element is 0.0021%.

[0028] Example 7 A method for producing high-purity silver powder using photovoltaic cells includes the following steps: S1. Take waste photovoltaic cells and soak them in 6 mol / L sulfuric acid solution at 42 °C for 40 min for pretreatment to obtain pretreated photovoltaic cells. S2. Mix the pretreated photovoltaic cells and the oxidant at 50 °C for 12 min, then filter to obtain the reaction solution. The oxidant consists of hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 8:1. The mass-to-volume ratio of ammonium chromate to water in the ammonium chromate solution is 15 g:1 L. S3. After adding sodium glucoheptonate (the addition amount of sodium glucoheptonate is 0.5% of the mass of the reaction solution) to the reaction solution and mixing, filter press to remove the filter residue to obtain silver solution; S4. Add sodium chloride (the mass of sodium chloride is 8% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride; S5. Reduce the silver chloride with iron powder to obtain silver powder. The silver element content in the silver powder is 99.99%, the Cu element content is 0.0011%, and the Fe element content is 0.0016%.

[0029] Example 8 A method for producing high-purity silver powder using photovoltaic cell wafers includes the following steps: S1. Take waste photovoltaic cell wafers and soak them in 6 mol / L sulfuric acid solution at 42 °C for 40 min for pretreatment to obtain pretreated photovoltaic cell wafers; S2. Mix the pretreated photovoltaic cell wafers and an oxidant at 50 °C for 12 min and filter to obtain a reaction solution; the components of the oxidant are hydrogen peroxide (mass fraction 5 wt%) and ammonium chromate solution with a mass ratio of 8:1; the mass-volume ratio of ammonium chromate to water in the ammonium chromate solution is 15 g:1 L; S3. After adding sodium glucoheptonate (the addition amount of sodium glucoheptonate is 1.5% of the mass of the reaction solution) to the reaction solution and mixing, filter press to remove the filter residue to obtain silver solution; S4. Add sodium chloride (the mass of sodium chloride is 8% of the mass of the silver solution) to the silver solution for precipitation to obtain silver chloride; S5. Reduce the silver chloride with iron powder to obtain silver powder. The silver element content in the silver powder is 99.99%, the Cu element content is 0.0008%, and the Fe element content is 0.0016%.

[0030] Example 9 The difference between this example and Example 7 is only that sodium glucoheptonate is replaced by citric acid. The silver element content in the silver powder is 99.99%, the Cu element content is 0.0020%, and the Fe element content is 0.0023%.

[0031] Example 10 The difference between this example and Example 7 is only that sodium glucoheptonate is replaced by tartaric acid. The silver element content in the silver powder is 99.99%, the Cu element content is 0.0015%, and the Fe element content is 0.0025%.

[0032] Comparative Example 1 The difference between this comparative example and Example 3 is only that the oxidant is hydrogen peroxide with a mass fraction of 5wt%. The yield of silver powder is 93.6%, the silver element content in the silver powder is 98.95%, the Cu element content is 0.0096%, and the Fe element content is 0.01%.

[0033] Comparative Example 2 The difference between this comparative example and Example 3 is only that the component of the oxidant is hydrogen peroxide (mass fraction 5wt%) and ammonia water with a mass ratio of 10:1; the concentration of the ammonia water is 15g:1L, the yield of silver powder is 95.8%, the silver element content in the silver powder is 99.85%, the Cu element content is 0.0060%, and the Fe element content is 0.0048%.

[0034] Compared with Comparative Examples 1-2, the Cu element and Fe element contents in the silver powder produced from photovoltaic panel cells in Examples 1-10 are lower, and the yield of silver powder is higher. This shows that using hydrogen peroxide and ammonium salt solution as the components of the oxidant can improve the purity of high-purity silver powder produced from photovoltaic panel cells and also increase the yield of silver powder.

[0035] Compared with Examples 6 and 9-10, the Cu element and Fe element contents in the silver powder produced from photovoltaic panel cells in Examples 7-8 are lower, indicating that adding sodium glucoheptonate improves the purity of the silver powder when producing high-purity silver powder from photovoltaic panel cells.

[0036] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for producing high-purity silver powder using photovoltaic panel cells, characterized in that: The following steps are involved: S1, taking the waste photovoltaic cell and pre-treating it by soaking it in an acid solution to obtain a pre-treated photovoltaic cell; S2, mixing the pretreated photovoltaic cell and the oxidant, filtering, and obtaining a reaction solution; S3, post-treating the reaction solution to obtain silver liquid; S4, adding sodium chloride to the silver solution to obtain silver chloride; S5, reducing the silver chloride to obtain silver powder; The components of the oxidant include hydrogen peroxide and ammonium salt solution in a mass ratio of 5 to 10:

1.

2. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The concentration of the acid solution is 5-7 mol / L; The mass fraction of the hydrogen peroxide is 4wt%~5wt%; In the ammonium salt solution, the mass volume ratio of ammonium salt to water is 12-16 g:1 L.

3. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The ammonium salt includes one or more of ammonium chromate, magnesium ammonium phosphate, and aluminum ammonium phosphate.

4. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The acid solution includes one or more of hydrochloric acid solution, nitric acid solution and sulfuric acid solution.

5. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The mass of the sodium chloride is 5% to 10% of the mass of the silver liquid.

6. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: Sodium glucoheptonate was also added before the post-treatment.

7. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The amount of sodium glucoheptonate added is 0.5% to 1.5% of the mass of the reaction solution.

8. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The soaking pretreatment is performed at a temperature of 40-45° C. and for a time of 30-50 minutes.

9. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: The mixing temperature is 45-55° C. and the mixing time is 10-15 min.

10. The method for producing high-purity silver powder using photovoltaic panel cells according to claim 1, characterized in that: During the reduction, iron powder is used for reduction treatment.