Method for recovering silver and indium in heterojunction photovoltaic module

Abstract

The invention discloses a method for recycling silver and indium in a heterojunction photovoltaic module. The method comprises the following steps of module separation, leaching, extraction, indium extraction, silver extraction and the like. In the leaching and extraction processes, the indium-silver acid leaching liquid and the extraction agent are recycled, so that the consumption of auxiliary materials is reduced, and the recovery cost is effectively reduced; according to the method, the metal silver and the metal indium in the heterojunction photovoltaic module can be recovered at the same time, and the high-purity metal silver and the high-purity metal indium are obtained.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic component recycling, and in particular to a method for recycling silver and indium in a heterojunction photovoltaic component. Background Art

[0002] Since 2012, the installed capacity of photovoltaic power generation has shown a continuous growth trend. The service life of photovoltaic modules is usually between 20 and 25 years. It is expected that by around 2030, there will be a large-scale retirement of photovoltaic modules, and as the installed capacity increases, the retirement market will continue to expand. Therefore, the treatment of discarded photovoltaic modules has become a hot issue in resource utilization.

[0003] Photovoltaic modules are mainly divided into two categories: crystalline silicon modules and thin-film modules. Among them, crystalline silicon modules occupy about 90% of the market share and have become the focus of research for recycling companies. According to the type of cell, crystalline silicon modules are mainly divided into P-type modules, TOPCon modules and heterojunction modules. P-type and TOPCon modules mainly contain metallic silver, while heterojunction modules contain rare strategic metal indium in addition to metallic silver. At present, there have been many studies on the recovery methods of metallic silver for P-type and TOPCon modules. For example, Chinese patent CN 202210035995.X discloses a comprehensive recycling method for discarded photovoltaic modules, which achieves the recovery of silver and silicon powder through process flows such as mechanical disassembly, pyrolysis, chemical treatment, wet and pyroprocessing. However, there is currently a lack of effective solutions in the photovoltaic field for how to recover silver and indium from heterojunction modules. Summary of the invention

[0004] The purpose of the present invention is to provide a method for recovering silver and indium in heterojunction photovoltaic modules in order to solve the above problems. The present invention can simultaneously recover metallic silver and indium in heterojunction photovoltaic modules through key steps such as module separation, leaching, extraction, indium extraction and silver extraction, and can obtain high-purity metallic silver and indium.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A method for recovering silver and indium from a heterojunction photovoltaic module comprises the following steps:

[0007] Step A: Component separation:

[0008] 1) Mechanically dismantle the discarded heterojunction photovoltaic modules to separate the aluminum frame, junction box and laminated parts;

[0009] 2) shredding, crushing and sorting the disassembled laminated parts to obtain glass, EVA and battery cell powder;

[0010] Step B, leaching: leaching the battery cell powder with a sulfuric acid solution, filtering to obtain an indium silver acid leaching solution; repeating the leaching of the indium silver acid leaching solution 2 to 3 times according to the same process, filtering to obtain an indium-rich silver acid leaching solution;

[0011] Step C, extraction: P204 and sulfonated kerosene are used as extractants and added into the indium-silver acid leaching solution. After separation, the upper layer is the indium-containing oil phase and the lower layer is the silver-containing water phase;

[0012] Step D, extracting indium:

[0013] 1) Stripping: adding hydrochloric acid solution to the indium-containing oil phase obtained in step C for stripping, obtaining an indium-containing water phase after separation, and returning the oil phase to step C for repeated use;

[0014] 2) Replacement: Use sodium hydroxide to adjust the pH of the indium-containing aqueous phase to 0.5, then add zinc powder thereto, and replace at room temperature to obtain sponge indium;

[0015] 3) Alkali melting: put sponge indium and caustic soda flakes into a crucible in a mass ratio of 1:1, heat the muffle furnace to 400°C, stir after all are melted, skim off the scum, and cool the molten liquid to obtain crude indium;

[0016] 4) Electrolysis: Use alkali-melted crude indium as the anode plate, pure titanium plate as the cathode, and indium sulfate as the electrolyte for electrolysis. Electrolytic indium is obtained on the titanium plate, and indium ingots are obtained after stripping;

[0017] Step E: Withdraw silver:

[0018] 1) Precipitation: adding NaCl to the silver-containing aqueous phase obtained in step C, filtering to obtain silver chloride, and drying;

[0019] 2) Melting reduction: Mix silver chloride, borax, potassium nitrate and sodium carbonate in a mass ratio of 55%, 15%, 5% and 25%, put them into a medium frequency furnace for heating and replacement, and obtain silver ingots after cooling.

[0020] A further solution is that in step B, the mass concentration of the sulfuric acid solution is 10% to 20%, the ratio of battery powder to sulfuric acid solution is 1:2 to 4, the leaching time is 1 to 4 hours, and the leaching temperature is 40 to 60°C.

[0021] A further solution is that in step C, the volume ratio of P204 to sulfonated kerosene is 3:7-9, and the volume ratio of P204 to indium silver acid leaching solution is 1:5-7.

[0022] A further solution is that in step D, the concentration of the hydrochloric acid solution is 3 mol / L, and the volume ratio of hydrochloric acid to the indium-containing oil phase is 1:10-15; the amount of zinc powder added is 2-4 times the molar concentration of indium in the indium-containing water phase; the replacement temperature is room temperature, and the replacement time is 1-4 hours.

[0023] A further solution is that in step E, the amount of NaCl added is 1 to 2 times the molar concentration of silver in the silver-containing aqueous phase.

[0024] A further solution is that in step E, the temperature of the medium frequency furnace is controlled by slowly heating the temperature to 600° C., keeping the temperature for 1 to 2 hours, and then rapidly heating the temperature to 1100° C.

[0025] The beneficial effects of the present invention are:

[0026] The invention discloses a method for recovering silver and indium in a heterojunction photovoltaic module. The method can simultaneously recover metallic silver and indium in a heterojunction photovoltaic module through key steps such as module separation, leaching, extraction, indium extraction and silver extraction, and can further obtain metallic silver and indium with high purity. In the leaching and extraction process, the consumption of auxiliary materials is significantly reduced by recycling the indium-silver acid leaching solution and the extractant, thereby effectively reducing the cost of the entire recovery process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0029] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0030] Example 1

[0031] A. Component separation: 10 320W heterojunction photovoltaic modules were mechanically disassembled to separate the aluminum frame, junction box and laminated parts; the laminated parts were torn, crushed and sorted to obtain glass, EVA and battery cell powder, with about 7kg of battery cell powder.

[0032] B. Leaching: Take 500g of battery powder in a beaker, add 1L of sulfuric acid solution with a mass concentration of 10%, react at 40°C for 4h under stirring, and filter to obtain an indium silver primary acid leaching solution; repeat the leaching of the indium silver primary acid leaching solution twice according to the same process, and filter to obtain an indium silver-rich acid leaching solution.

[0033] C. Extraction: Prepare an extractant with P204 and sulfonated kerosene, wherein the volume ratio of P204 to sulfonated kerosene is 3:7. Add the extractant into the indium-rich silver acid leaching solution at a volume ratio of 1:5. After shaking, let it stand for 10 minutes. After separation, the upper layer is the indium-containing oil phase, and the lower layer is the silver-containing water phase.

[0034] D. Extraction of indium:

[0035] 1) Stripping: Add 3 mol / L hydrochloric acid solution to the indium-containing oil phase obtained in step C for stripping, the volume ratio of hydrochloric acid solution to indium-containing oil phase is 1:10, shake and let stand for 10 minutes, separate and obtain indium-containing water phase, and retain the oil phase for repeated use.

[0036] 2) Replacement: Use sodium hydroxide to adjust the pH of the indium-containing aqueous phase to 0.5, detect the concentration of indium in the indium-containing aqueous phase, add zinc powder in a 2-fold molar amount, and react at room temperature for 1 hour to obtain sponge indium.

[0037] 3) Alkali melting: put sponge indium and caustic soda flakes into a crucible at a mass ratio of 1:1, heat the muffle furnace to 400°C, stir after all are melted, skim off the scum, and cool the molten liquid to obtain crude indium.

[0038] 4) Electrolysis: Use alkali-melted crude indium as the anode plate, pure titanium plate as the cathode, and indium sulfate as the electrolyte for electrolysis. Electrolytic indium is obtained on the titanium plate. After stripping, 2.2g of indium ingot is obtained. After testing, the purity of the indium ingot is 99.99%.

[0039] E. Withdrawal of Silver:

[0040] 1) Precipitation: Add NaCl to the silver-containing aqueous phase obtained in step C, filter to obtain silver chloride, and dry.

[0041] The concentration of silver in the silver-containing aqueous phase was detected, and NaCl was added in a 1-fold molar amount. After reacting at room temperature for 1 hour, silver chloride was obtained after filtering, washing, and drying.

[0042] 2) Melting reduction: silver chloride, borax, potassium nitrate and sodium carbonate are mixed evenly in a mass ratio of 55%, 15%, 5% and 25%, and heated in a medium frequency furnace. The temperature control method of the medium frequency furnace is to slowly heat up to 600°C, keep warm for 1 hour and then quickly heat up to 1100°C. When the brightness of the slag surface becomes dark and the melt no longer churns, the slag can be poured. The molten silver is poured into a mold and cooled to obtain a silver ingot. The mass of the silver ingot is 10.5g, and the quality meets the IC-Ag99.90 standard.

[0043] Example 2

[0044] A. Component separation: same as in Example 1;

[0045] B. Leaching: Take 500g of battery powder in a beaker, add 1L of sulfuric acid solution with a mass concentration of 10%, react at 60°C for 3h under stirring, and filter to obtain an indium silver primary acid leaching solution; repeat the leaching of the indium silver primary acid leaching solution twice according to the same process, and filter to obtain an indium silver-rich acid leaching solution.

[0046] C. Extraction: Prepare an extractant with P204 and sulfonated kerosene, wherein the volume ratio of P204 to sulfonated kerosene is 3:7. Add the extractant into the indium-rich silver acid leaching solution at a volume ratio of 1:5. After shaking, let it stand for 10 minutes. After separation, the upper layer is the indium-containing oil phase, and the lower layer is the silver-containing water phase.

[0047] D. Extraction of indium:

[0048] 1) Stripping: Add 3 mol / L hydrochloric acid solution to the indium-containing oil phase obtained in step C for stripping, the volume ratio of hydrochloric acid solution to indium-containing oil phase is 1:10, shake and let stand for 10 minutes, separate and obtain indium-containing water phase, and retain the oil phase for repeated use.

[0049] 2) Replacement: Use sodium hydroxide to adjust the pH of the indium-containing aqueous phase to 0.5, detect the concentration of indium in the indium-containing aqueous phase, add zinc powder in a 2-fold molar amount, and react at room temperature for 1 hour to obtain sponge indium.

[0050] 3) Alkali melting: put sponge indium and caustic soda flakes into a crucible at a mass ratio of 1:1, heat the muffle furnace to 400°C, stir after all are melted, skim off the scum, and cool the molten liquid to obtain crude indium.

[0051] 4) Electrolysis: Use alkali-melted crude indium as the anode plate, pure titanium plate as the cathode, and indium sulfate as the electrolyte for electrolysis. Electrolytic indium is obtained on the titanium plate. After stripping, 2.1g of indium ingot is obtained. After testing, the purity of the indium ingot is 99.99%.

[0052] E. Withdrawal of Silver:

[0053] 1) Precipitation: Add NaCl to the silver-containing aqueous phase obtained in step C, filter to obtain silver chloride, and dry.

[0054] The concentration of silver in the silver-containing aqueous phase was detected, and NaCl was added in a 1-fold molar amount. After reacting at room temperature for 1 hour, silver chloride was obtained after filtering, washing, and drying.

[0055] 2) Melting reduction: Mix silver chloride, borax, potassium nitrate and sodium carbonate in a mass ratio of 55%, 15%, 5% and 25% and heat them in a medium frequency furnace. The temperature control method of the medium frequency furnace is to slowly heat up to 600°C, keep it warm for 1h and then quickly heat up to 1100°C. When the brightness of the slag surface becomes darker and the melt no longer churns, the slag can be poured. The molten silver is poured into a mold and cooled to obtain a silver ingot. The mass of the silver ingot is 11.2g, and the quality meets the IC-Ag99.90 standard.

[0056] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. It should also be noted that the various specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further explain various possible combinations. In addition, the various different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for recovering silver and indium from heterojunction photovoltaic modules, characterized in that: The following steps are involved: Step A: Component separation: 1) Mechanically dismantle the discarded heterojunction photovoltaic modules to separate the aluminum frame, junction box and laminated parts; 2) Shredding, crushing and sorting the disassembled laminated parts to obtain glass, EVA and battery cell powder; Step B, leaching: leaching the battery cell powder with a sulfuric acid solution, filtering to obtain an indium silver acid leaching solution; repeating the leaching of the indium silver acid leaching solution 2 to 3 times according to the same process, filtering to obtain an indium-rich silver acid leaching solution; Step C, extraction: P204 and sulfonated kerosene are used as extractants and added into the indium-silver acid leaching solution. After separation, the upper layer is the indium-containing oil phase and the lower layer is the silver-containing water phase; Step D, extracting indium: 1) Stripping: adding hydrochloric acid solution to the indium-containing oil phase obtained in step C for stripping, obtaining an indium-containing water phase after separation, and returning the oil phase to step C for repeated use; 2) Replacement: Use sodium hydroxide to adjust the pH of the indium-containing aqueous phase to 0.5, then add zinc powder thereto, and replace at room temperature to obtain sponge indium; 3) Alkali melting: put sponge indium and caustic soda flakes into a crucible in a mass ratio of 1:1, heat the muffle furnace to 400°C, stir after all are melted, skim off the scum, and cool the molten liquid to obtain crude indium; 4) Electrolysis: Use alkali-melted crude indium as the anode plate, pure titanium plate as the cathode, and indium sulfate as the electrolyte for electrolysis. Electrolytic indium is obtained on the titanium plate, and indium ingots are obtained after stripping; Step E: Withdraw silver: 1) Precipitation: adding NaCl to the silver-containing aqueous phase obtained in step C, filtering to obtain silver chloride, and drying; 2) Melting reduction: Mix silver chloride, borax, potassium nitrate and sodium carbonate in a mass ratio of 55%, 15%, 5% and 25%, put them into a medium frequency furnace for heating and replacement, and obtain silver ingots after cooling.

2. A method for recovering silver and indium from heterojunction photovoltaic modules according to claim 1, characterized in that: In the step B, the mass concentration of the sulfuric acid solution is 10% to 20%, the ratio of battery powder to sulfuric acid solution is 1:2 to 4, the leaching time is 1 to 4 hours, and the leaching temperature is 40 to 60°C.

3. A method for recovering silver and indium from heterojunction photovoltaic modules according to claim 1, characterized in that: In step C, the volume ratio of P204 to sulfonated kerosene is 3:7-9, and the volume ratio of P204 to indium silver acid leaching solution is 1:5-7.

4. A method for recovering silver and indium from heterojunction photovoltaic modules according to claim 1, characterized in that: In the step D, the concentration of the hydrochloric acid solution is 3 mol / L, and the volume ratio of hydrochloric acid to the indium-containing oil phase is 1:10-15; the amount of zinc powder added is 2-4 times the molar concentration of indium in the indium-containing water phase; the replacement temperature is room temperature, and the replacement time is 1-4 hours.

5. A method for recovering silver and indium from heterojunction photovoltaic modules according to claim 1, characterized in that: In the step E, the amount of NaCl added is 1 to 2 times the molar concentration of silver in the silver-containing aqueous phase.

6. A method for recovering silver and indium from heterojunction photovoltaic modules according to claim 1, characterized in that: In the step E, the temperature of the medium frequency furnace is controlled by slowly heating the temperature to 600° C., keeping the temperature for 1 to 2 hours, and then rapidly heating the temperature to 1100° C.

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