KR20120000148A - Method for recycling silicon from waste solar module - Google Patents

Abstract

PURPOSE: A method for collecting silicon from solar cell module waste is provided to collect pure silicon and recycle the collected silicon as a silicon wafer by collecting cells from the solar cell module waste and eliminating a non-reflective coating layer and electrode materials from the cells. CONSTITUTION: Solar cell module waste is immersed in an organic solvent in order to collect cells(11) based on the swelling phenomenon of ethylene vinyl acetate(EVA)(12). Trichloroethylene, o-dichlorobenzene, or toluene is used as the organic solvent. Reinforced glass(14), separated from the cells based on the swelling phenomenon of the EVA, is collected. Cells attached to the EVA are passed through a furnace of 500-700 degrees Celsius under an inert atmosphere condition in order to pyrolyze the EVA. The cells are collected. A mixed acid solvent is obtained by mixing distilled water, nitric acid, fluoric acid, sulfuric acid, and acetic acid. A mixed solvent is obtained by additionally mixing surfactant to the mixed acid solvent. The collected cells are immersed in the mixed solvent to dissolve a non-reflective coating layer and electrode materials. Pure silicon is collected.

Description

Silicon recovery method in solar cell waste module {METHOD FOR RECYCLING SILICON FROM WASTE SOLAR MODULE}

The present invention relates to a method for recovering silicon from a solar cell waste module, and more particularly, to recover tempered glass and cells by removing EVA (Ethylene Vinyl Accetate) from the solar cell waste module, and to reflect the anti-reflection from the recovered solar cell. The present invention relates to a method for recovering pure silicon by removing the coating film and the electrode material.

In order to solve the environment and energy problems, a lot of researches are being conducted in the field of renewable energy. Among them, solar cells using a new energy source called solar energy are rapidly emerging as an object of interest and are currently being commercialized and actively used. In general, solar cells convert energy from sunlight into electrical energy and generate electricity using two types of semiconductors, P-type semiconductors and N-type semiconductors, which are inexpensive and can be used semi-permanently without causing pollution. Therefore, it is a renewable energy that is spotlighted as an alternative energy.

Explains the principle of electricity generation of solar cells, and when light is irradiated on the solar cells, electrons and holes are generated inside the solar cells, and the generated charges move to the P and N poles, thereby generating a potential difference between the P and N poles. At this time, the current flows when the load is connected to the solar cell.

Such solar cells may be classified into silicon solar cells, compound semiconductor solar cells, and organic solar cells according to materials, and are classified into bulk and thin film types according to the type of substrate, the type of silicon wafer and glass, and the like.

The bulk silicon solar cell is further divided into polycrystalline and single crystal crystalline solar cells according to the type of silicon.

Looking at the manufacturing method of the most widely used crystalline silicon solar cell, occupying more than 90% of the world's rapidly growing photovoltaic market, the step of making metal silicon (99% purity) by refining raw materials such as quartz and sand, Refining it to make polysilicon for solar cell (purity 6N or more), and then purifying the produced polysilicon to make single crystal or polycrystalline ingot, cutting it to make silicon wafer, and then forming PN junction and electrode Finally, the solar cell is manufactured.

The monocrystalline solar cell manufactured as described above has a disadvantage in that the power generation efficiency is higher than that of the polycrystalline solar cell, but the price is a little expensive, but the power generation efficiency is high even on a cloudy or rainy day.

In contrast, polycrystalline solar cells are less efficient than single crystal solar cells, but are easy to process and easily mass-produced, so that they can be supplied at a low price.

In the solar cell substrate market, the supply of silicon is reaching its limit due to a sharp increase in module production, and the price of substrate is expected to increase due to deterioration of silicon raw material supply.

On the other hand, in the process of making a solar cell module, first, a cell is made by attaching an antireflective coating film and an electrode material to a silicon wafer, and a plurality of cells thus made are covered with transparent EVA (ethylene vinyl acetate) to cover the front and the back of the cell. Then, the tempered glass on one side is covered with a back sheet on the other side to give heat and pressure, and then it is manufactured as a module. Then, a terminal box is installed to use power and an aluminum frame is installed at the edge of the module.

Meanwhile, the price ratio of the module in the solar cell system is 55%, the price ratio of silicon in the module is 50%, and silicon is the most important factor in the solar cell system. In addition, tempered glass, which affects the light transmission of the sunlight and the durability of the solar cell, is also an important material to be recovered.

However, at present, since the technology for recovering silicon and tempered glass from solar cells is weak, most of the recovered solar cell modules are crushed and crushed, buried in the ground, or sold at low prices to foreign countries. Therefore, the recovery of silicon and tempered glass from the solar cell module is an environmentally and economically important technology.

In order to recover silicon and tempered glass from the solar cell module, the first task is to remove the EVA used as the adhesive for the cell and tempered glass.

The conventional method for removing EVA includes thermal decomposition using the melting point of EVA using high temperature heat in an inert gas such as nitrogen or argon, and removing EVA by melting EVA by immersing in high temperature nitric acid. There are nitric acid dipping method and organic solvent method for recovering tempered glass and silicon by expanding EVA with organic solvent.

However, in the case of pyrolysis, the size of equipment and furnace to be used is limited according to the size of the solar cell module, which makes it difficult to install and manufacture. Also, when pyrolysis, cross linking (high temperature EVA between tempered glass and cells) EVA, which acts as an adhesive through overpressure and becomes a polymer on the surface of the tempered glass and the cell surface, remains on the surface of the cell and the tempered glass.

In addition, the nitric acid immersion method is difficult to penetrate nitric acid between the tempered glass and the cell, and a considerable time is required even if the nitric acid temperature is increased to a high temperature. In particular, even if the EVA is recovered and the cell and the tempered glass are recovered, the remaining white matter, the remaining substance of the EVA, must remain on the surface and be removed later with an organic solvent. It is very difficult to get. In addition, the surface cleaning technology is not yet established.

Therefore, by developing a technology to recover pure silicon from the solar cell waste module, efforts are needed to solve the problem of shortage of silicon, to reduce solar cell manufacturing cost and waste disposal cost.

The present invention has been invented to solve the above problems, to find the optimal conditions for recovering silicon, which is the core material of the solar cell module, to recover the silicon most efficiently and to recycle the material of the solar cell It is an object of the present invention to provide a method for recovering silicon in a battery waste module.

In order to achieve the above object, a method for recovering silicon in a solar cell waste module according to the present invention includes: a) the waste module for recovering a cell using the swelling phenomenon of EVA (Ethylene Vinyl Accetate) in the solar cell waste module; Dipping in an organic solvent; b) first recovering the tempered glass separated from the cell by swelling of the EVA; c) thermally decomposing EVA in a furnace at 500-700 ° C. to remove the cells attached to the expanded EVA from which the tempered glass was removed, and recovering the cells; d) preparing a mixed solvent by mixing distilled water, nitric acid, hydrofluoric acid, sulfuric acid and acetic acid, and preparing a mixed solvent in which a surfactant is further mixed with the mixed acid solvent; e) detecting the immersion time to obtain the highest recovery rate of silicon by immersing the cell recovered in the step c) by changing the immersion time in the prepared mixed solvent; f) dissolving the recovered cell in the mixed solvent according to the detected optimal immersion time to dissolve the antireflective coating film and the electrode material; g) recovering the pure silicon from which the antireflective coating film and the electrode material are removed from the cell immersed in the mixed solvent.

In addition, the organic solvent of step a) is characterized in that any one of trichloroethylene, o-dichlorobenzene or toluene.

In addition, the mixed acid solvent of step d) is 60 to 70% by weight of distilled water, 20 to 30% by weight of nitric acid and 5 to 10% by weight of hydrofluoric acid, 3 to sulfuric acid with respect to 100 parts by weight of the mixture of distilled water, nitric acid and hydrofluoric acid 7 parts by weight, acetic acid 3 to 7 parts by weight of the solvent is characterized by further mixing.

In addition, the amount of the surfactant further mixed in step d) is characterized in that 20 to 30% of the total volume of the mixed acid solvent consisting of distilled water, nitric acid, hydrofluoric acid, sulfuric acid and acetic acid.

According to the silicon recovery method of the solar cell waste module according to the present invention, the cell is recovered from the solar cell waste module, the anti-reflective coating film and the electrode material are removed from the recovered cell, and the pure silicon is recovered to recycle the silicon wafer. It is possible.

In particular, by recovering and recycling the silicon used in the solar cell as an expensive material, it is possible to reduce the production price of the solar cell and increase productivity.

1 is a schematic view showing a general solar cell module,
2 schematically shows the mechanism by which the removal material of the cell surface is separated when a surfactant is used;
FIG. 3 is a schematic diagram showing different reactions of a cross linking part and a non-cross linking part of EVA when the solar cell waste module is immersed in an organic solvent.

Hereinafter, a preferred embodiment of the silicon recovery method in the solar cell waste module according to the present invention will be described in detail.

According to an embodiment of the present invention, EVA (Ethylene Vinyl Acetate) is obtained by first immersing an old solar cell waste module or a defective solar cell waste module produced during the manufacturing process and immersing it in a preselected organic solvent through a basic experiment for a predetermined time. ) Swells up to recover tempered glass and cells. At this time, the tempered glass is removed, and the cell with swelled EVA is thermally decomposed in an inert atmosphere, a furnace of 500 to 700 ° C. to recover the cell. Finally, the recovered cells are immersed in various mixed solvents at room temperature for a certain time to recover the silicon from which the anti-reflective coating film and the electrode material have been removed, and are dissolved in the recovered silicon and mixed solution through ICP (Inductively Coupled Plasma) analysis. The amount of silicon present is analyzed to calculate the recovery of silicon. Using the silicon recovery rate thus calculated, it is possible to effectively recover the silicon by providing the optimum mixed acid solvent condition and mixed acid immersion time.

Thus, the present invention is to recover the tempered glass and cells by immersing the solar cell waste module in the selected organic solvent, immersed in the optimal mixed acid solvent to remove the antireflective coating film and electrode material, and then to recover the remaining pure silicon Make sure to recycle it.

1 is a schematic view showing a general solar cell module.

As shown, the solar cell module is supported by both frames 16 and consists of tempered glass 14, EVA 12, cell 11, back sheet 13, back box, terminal box 15, and the like. do.

The tempered glass 14 serves as a surface material to protect the cell 11 from external impact. The EVA 12 serves as a filler and is a copolymer of ethylene and vinyl acetate, which is a vinyl film having excellent transparency, buffering capacity, elasticity, and tensile strength.

The cell 11 serves to convert light energy into electrical energy, and a plurality of cells 11 are connected in series or in parallel by conductive ribbons. The back sheet 13 plays a role of waterproofing, insulation and UV protection, and may be made of PVF, polyester, acrylic, or the like. The frame 16 is made of aluminum to support each component of the solar cell module, and the terminal box 15 is connected to the connection terminal and the power line of the solar cell module inside the housing to protect the connection and prevent leakage. Plays the role of.

Hereinafter, preferred embodiments of the present invention will be described.

The method for recovering silicon according to the present invention 1) first recovers tempered glass and cells by using an organic solvent, and the EVA swells when the solar cell waste module is immersed in a preselected organic solvent through a basic experiment for 7 to 14 days. The tempered glass separated from the cell can be recovered. 2) After removing the tempered glass by the above steps, the cell with the expanded EVA is removed by pyrolysis of the EVA in an inert atmosphere at a temperature of 500 to 700 ° C. to recover the cell. 3) Finally, the recovered cell is pure silicon by removing both the antireflective coating film and electrode material by using mixed acid solvent dipping. The recovery rate of the pure silicon is calculated through ICP analysis to determine the optimum mixed acid solvent and the appropriate immersion time in recovering the silicon. In this case, the recovered cells are immersed in the mixed solvent in which the surfactant is added to the mixed acid solvent prepared above to compare the recovery rate of the silicon, and the recovery rate of the pure silicon from which the antireflective coating film and the electrode material are removed is compared.

In the present invention, an organic solvent such as trichloroethylene, o-dichlorobenzene, toluene, and the like selected through a basic experiment was used for recovery of the tempered glass and the cell. After supplying the old solar cell waste module which has been judged to be old or defective in manufacturing, the backsheet of the solar cell waste module received is removed by physical force, and then immersed in the organic solvent for 7 to 14 days to organic matter between the tempered glass and the cell. The solvent penetrates and the EVA swells. At this time, when the EVA swells, the tempered glass and the cell that are firmly bonded are separated, and the tempered glass and the cell can be recovered.

Basic experiment results of removing EVA by immersing the waste module for 48 hours in various solvents are shown in Table 1 below.

Solvent immersion time Immediately after dipping 30 minutes 2 hours 3 hours 30 minutes 24 hours 48 hours 2-propanol clear clear clear clear clear clear 4-methyl-2-pentanone Swell slightly Swell slightly Swell slightly Swell slightly Swell slightly Swell slightly
petroleum benzene Swell slightly
(10 ml
Solvent
Reduced amount)

Swell slightly

Swell slightly

Swell slightly
Swell slightly
(All reagents
Withered)
Swell slightly
(All reagents
Withered) tetrahydro furan Inflate-> Transparent Record all Record all Record all Record all Record all trichloro ethylene Almost disassembled
(Invisible) Record all Record all Record all Record all Record all
toluene
Almost melted
Stick to the floor
(Transparency)
Record all

Record all

Record all

Record all

Record all
o-dichloro benzene Inflate-> Transparent Almost recorded Record all Record all Record all Record all glycerin No change No change No change No change No change No change acetone No change No change No change No change No change No change ethylalcohol No change No change No change No change No change No change

The size of EVA used in the basic experiment was 5 × 30 × 0.5 mm, the amount of organic solvent was 10 ml, and the temperature was performed at room temperature. As can be seen from the experimental results, it can be seen that tetrahydrfuran, trichloroethylene, o-dichlorobenzene, and toluene are efficient solvents for EVA removal.

Trichloroethylene, o-dichlorobenzene, or toluene, selected by the basic experiment, has a property of decomposing and dissolving or expanding EVA. Therefore, when the solar cell waste module is immersed in the organic solvent, the organic solvent penetrates between the tempered glass and the cell to melt or expand the EVA. At this time, the part where EVA melts is a non-cross linking part where the tempered glass and the cell do not touch, and the part that is expanded is a cross linking part where the cell and the tempered glass contact. FIG. 3 shows the molecular structure of EVA and non-cross linking and cross linking of EVA.

After swelling the EVA by the above method, the tempered glass is recovered first, and the cell with the swelled EVA removed from the tempered glass is in an inert atmosphere, and the cell is removed by pyrolyzing the EVA in a furnace at 500 to 700 ° C. Recover. Finally, the recovered cell was prepared by mixing a mixed acid solvent capable of selectively dissolving an antireflective coating film and an electrode material, and immersing the mixed acid solvent.

The mixed acid solvent is prepared by selecting four acids such as nitric acid, nitric acid, hydrofluoric acid, sulfuric acid, and acetic acid. And the surfactant was used to increase the recovery rate, the type of the surfactant is not particularly limited and may be used cationic surfactant, anionic surfactant, amphoteric surfactant or nonionic surfactant.

In order to examine the recovery rate of silicon depending on the presence or absence of a surfactant, a mixed acid solvent is prepared in two compositions. The first mixed acid solvent is a mixed solvent prepared by mixing all four acids such as nitric acid, hydrofluoric acid, sulfuric acid, and acetic acid, and adding a surfactant corresponding to 20 to 30% of the total volume of the mixed solution. On the other hand, the second mixed acid solvent was prepared with only four acids without adding a surfactant in the first mixed acid solvent.

When the preparation of each mixed acid solvent is completed, the recovered cells are immersed in two kinds of mixed acid solvents, respectively. At this time, the recovered cell is immersed by varying the immersion time for each mixed acid solvent, thereby determining the optimum time to remove the antireflective coating film and the electrode material from the cell and at the same time recover the maximum silicon.

When the antireflective coating film and the electrode material are dissolved in a cell immersed in a mixed acid solvent at room temperature for a predetermined time, only pure silicon is recovered, and all mixed acid solvents on the surface are washed with distilled water.

Next, the weight of the recovered silicon was measured, and the silicon dissolved in the mixed acid solution containing silicon dissolved according to the anti-reflective coating film, the electrode material, and the mixed acid solvent immersion time was analyzed in ppm units through ICP analysis. Calculate the amount of initial silicon you put in. Thus, by evaluating the recovery rate of silicon according to the type of acid contained in the mixed acid solvent and the cell immersion time to determine the optimal composition of the mixed acid solvent and the immersion time of the cell for the maximum recovery of pure silicon in the cell.

In the present invention, in order to determine the mixed acid solvent for the optimum comparison of silicon recovery, two types of mixed acid solvents, a first mixed solvent and a second mixed solvent, are prepared. The first mixed acid solvent using all four acids and adding a surfactant is mixed with 60 to 70% by weight of distilled water, 20 to 30% by weight of nitric acid and 5 to 10% by weight of hydrofluoric acid, and 100% by weight of the mixture of distilled water, nitric acid and hydrofluoric acid. 3 parts by weight of sulfuric acid and 3 to 7 parts by weight of acetic acid are further mixed with respect to the part. It was prepared by adding a surfactant corresponding to 20 to 30% of the total volume.

On the other hand, the second mixed acid solvent is prepared by mixing only the acid without adding a surfactant corresponding to 20 to 30% of the volume additionally added in the first mixed acid solvent in order to compare the recovery rate of the silicon according to the surfactant.

The present invention provides an optimal method for pure silicon recovery from the solar cell 11 of the solar cell module from which the tempered glass 14 and the EVA 12 are removed through the above process.

Hereinafter, the effect of the present invention will be described through comparison data specifically prepared in Examples and Comparative Examples according to the present invention. However, the scope of the present invention is not limited to the following examples and can be easily inferred without departing from the spirit and scope of the present invention is construed as belonging to the scope of the present invention.

Example  One

The supplied solar cell waste module is immersed in the selected organic solvent for 7-14 days to recover the tempered glass separated from the cell by using the swelling of EVA. Cells with swelled EVA removed from tempered glass are pyrolyzed to remove EVA in an inert atmosphere at 600 ° C and the cells are recovered. Finally, the recovered cell is immersed in a mixed acid solvent prepared as follows to remove the antireflective coating film and electrode material and obtain pure silicon.

A mixed solution was prepared by mixing 70% by weight of distilled water, 20% by weight of nitric acid and 10% by weight of hydrofluoric acid, and a mixed acid solvent was further prepared by mixing 5 parts by weight of sulfuric acid and 5 parts by weight of acetic acid with respect to 100 parts by weight of the mixed solution. A first mixed solvent was prepared by further adding a surfactant corresponding to 20% of the total volume of the solvent. The surfactant used in this example is CMP-MO2 (Kanto Chemical).

The cells recovered before the first mixed acid solvent prepared were immersed at room temperature for 60 minutes. After a certain period of time, the cell started to bubble with the first mixed solvent, and after 60 minutes, the pure silicon removed by dissolving the antireflective coating film and electrode material was removed using tweezers, washed in distilled water, and dried at room temperature. .

Dry all the distilled water on the surface of the recovered silicon and visually check that both the antireflective coating film and the electrode material have been removed and weigh.

Next, after immersing the solar cell to weigh the first mixed solution in which the antireflective coating film, the electrode material, and a portion of the silicon are dissolved, and after ICP analysis, the weight of the recovered silicon and the dissolved silicon in the first mixed solution The amount was used to calculate the silicon recovery.

Example  2

The silicon was recovered in the same manner as in Example 1, but the immersion time of the cells in the first mixed solvent was changed to 50 minutes.

Example  3

The silicon was recovered in the same manner as in Example 1, but the immersion time of the cells in the first mixed solvent was changed to 40 minutes.

Example  4

The silicon was recovered in the same manner as in Example 1, but the immersion time of the cells in the first mixed solvent was changed to 30 minutes.

Example  5

The silicon was recovered in the same manner as in Example 1, but the immersion time of the cells in the first mixed solvent was changed to 20 minutes.

Example  6

The silicon was recovered in the same manner as in Example 1, but the immersion time of the cells in the first mixed solvent was changed to 10 minutes.

Comparative example  One

A mixed liquid was prepared by mixing 70% by weight of distilled water, 20% by weight of nitric acid and 10% by weight of hydrofluoric acid, and 5 parts by weight of sulfuric acid and 5 parts by weight of acetic acid were further mixed with 100 parts by weight of the mixture to prepare a second mixed solvent.

The silicon was recovered in the same manner as in Example 1, except that the second mixed solvent using no surfactant was used.

Comparative example  2

The silicon was recovered in the same manner as in Example 2, except that a second mixed acid solvent without adding a surfactant was used.

Comparative example  3

The silicon was recovered in the same manner as in Example 3, except that a second mixed acid solvent without adding a surfactant was used.

Comparative example  4

The silicon was recovered in the same manner as in Example 4, except that a second mixed acid solvent without adding a surfactant was used.

Comparative example  5

The silicon was recovered in the same manner as in Example 5, except that a second mixed acid solvent without adding a surfactant was used.

Comparative example  6

Recovering the silicon in the same manner as in Example 6, but using a second mixed acid solvent without adding a surfactant.

ICP analysis results for Examples 1 to 6 and Comparative Examples 1 to 6 are shown in Table 2 below. This analysis is based on the Jobin-Yvon Ultima-C Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES).

Sample Name ＼ Analysis Items Si (ppm) Sample Name ＼ Analysis Items Si (ppm) Example 1 1910 Comparative Example 1 1290 Example 2 2430 Comparative Example 2 1250 Example 3 2610 Comparative Example 3 1540 Example 4 1490 Comparative Example 4 1030 Example 5 1460 Comparative Example 5 601 Example 6 - Comparative Example 6 -

In Examples 1 to 5, pure silicon obtained by removing both of the antireflective coating film and the electrode material was obtained. As shown in Table 3, approximately 85% of the samples were immersed in the first mixed solvent for 20 minutes in the first mixed solvent. High silicon recovery was observed.

In addition, Comparative Example 5 in which the cell was immersed in the second mixed solvent for 20 minutes showed a relatively good recovery of silicon of 80%. On the other hand, in Example 6 and Comparative Example 6 having a immersion time of 10 minutes, it was observed that the antireflective coating film and the electrode material were not completely removed. Therefore, the time for immersing the solar cell in the mixed acid solvent can be determined about 20 minutes to 60 minutes. Table 3 shows the recovery rate of silicon with each mixed solvent and immersion time. Here, the mixed acid solution refers to a solution in which an antireflective coating film, an electrode material, and a part of silicon are dissolved in the first mixed acid solvent or the second mixed acid solvent.

Name of sample
Recovered
Si (mg)
Mixed acid solution
weight
In mixed acid solution
Melted Recovery
(%)
Si (ppm) Si (mg) conversion Example 1 283.6 73.290 1290 94.54 75 Comparative Example 1 210 62.780 1910 119.9 63.65 Example 2 256.3 73.070 1250 91.33 73.72 Comparative Example 2 258.5 63.240 2430 153.67 62.72 Example 3 397 72.860 1540 112.2 78 Comparative Example 3 362.7 62.960 2610 164.33 68.8 Example 4 402.8 73.140 1030 75.33 84.25 Comparative Example 4 294.9 63.430 1490 94.51 75.73 Example 5 292 73.060 601 43.9 86.9 Comparative Example 5 366.8 63.940 1460 93.35 79.71

As can be seen from the results of Table 3, the first mixed solvent added with the surfactant showed a higher silicon recovery of about 10% or more than the second mixed solvent without the addition.

Surfactants are substances that adsorb on the interface to lower the free energy of the interface and significantly change the properties of the interface. Chemical structures are both lipophilic materials having both a hydrophilic group having affinity with water and a lipophilic group having affinity with oil in one molecule. Such surfactants are used as laundry agents, softeners and the like. The action of the surfactant has various functions depending on its structure such as emulsification, solubilization, dispersion, washing, defoaming, foaming, antistatic, moisturizing, sterilization, and lubrication.

The surfactants used in this experiment are anti-reflective coatings and electrodes that adhere to the cell by moistening (wetting), penetrating (evenly infiltrating), dispersing (dropping and breaking), and protecting (not reattaching to the interface). It serves to make it easier to remove the material. Therefore, the first mixed solvent with the surfactant and the second mixed solvent without the surfactant were immersed in the cell for the same time, but showed a difference in the silicon recovery rate. According to the obtained result, it can be observed that surfactant influences the recovery rate of silicone. The accompanying Figure 2 schematically shows a general separation mechanism when a surfactant is used between the cell surface and the removal material (antireflective coating).

As such, the present invention provides an efficient recovery method of tempered glass and silicon in the solar cell waste module. The EVA decomposition basic experiment was used to select the organic solvent that EVA can swell best, and the ICP analysis of the mixed acid solution in which the recovered cell was immersed to determine the amount of silicon in ppm and the amount of silicon recovered in the mixed acid solution. The mixed recovery solvent and the mixed acid immersion time were selected for the optimum recovery of silicon by comparing and evaluating the recovery rate of each mixed acid solvent and the mixed acid immersion time. In addition, the mixed acid solvent for recovering silicon of the present invention is mixed and used according to the composition of the optimum mixed acid solvent having the best recovery rate of silicon, and the silicon recovery is increased by adding a surfactant to the mixed acid solvent.

In the above described and described with respect to specific preferred embodiments of the present invention, the present invention is not limited to these embodiments, and those of ordinary skill in the art claim of the present invention to which the invention belongs It includes all the various forms of embodiments that can be implemented without departing from the spirit.

11 solar cell 12 EVA (Ethylene Vinyl Accetate)
13: backsheet 14: tempered glass
15: terminal box 16: frame

Claims (4)

a) immersing the waste module in an organic solvent to recover the cell by using the swelling phenomenon of ethylene vinyl accelerator (EVA) in the solar cell waste module;
b) first recovering the tempered glass separated from the cell by swelling of the EVA;
c) thermally decomposing EVA in a furnace at 500-700 ° C. to remove the cells attached to the expanded EVA from which the tempered glass was removed, and recovering the cells;
d) preparing a mixed solvent by mixing distilled water, nitric acid, hydrofluoric acid, sulfuric acid and acetic acid, and preparing a mixed solvent in which a surfactant is further mixed with the mixed acid solvent;
e) detecting the immersion time to obtain the highest recovery rate of silicon by immersing the cell recovered in the step c) by changing the immersion time in the prepared mixed solvent;
f) dissolving the recovered cell in the mixed solvent according to the detected optimal immersion time to dissolve the antireflective coating film and the electrode material;
g) recovering the pure silicon from which the antireflective coating film and the electrode material have been removed from the cell immersed in the mixed solvent;
Method for recovering silicon in the solar cell module, characterized in that it comprises a.
The method according to claim 1,
The organic solvent of step a) is trichloroethylene, o-dichlorobenzene (o-dichlorobenzene) or toluene (Toluene) characterized in that the silicon recovery method in the solar cell waste module, characterized in that any one.
The method according to claim 1,
The mixed acid solvent of step d) is mixed with 60 to 70% by weight of distilled water, 20 to 30% by weight of nitric acid and 5 to 10% by weight of hydrofluoric acid, and 3 to 7% by weight of sulfuric acid based on 100 parts by weight of the mixed solution of distilled water, nitric acid and hydrofluoric acid. Part, a method for recovering silicon in the solar cell waste module, characterized in that the solvent further mixed 3 to 7 parts by weight of acetic acid.
The method according to claim 3,
The amount of the surfactant additionally mixed in the step d) corresponds to 20-30% of the total volume of the mixed acid solvent consisting of distilled water, nitric acid, hydrofluoric acid, sulfuric acid and acetic acid.

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