DESC:FIELD OF THE INVENTION:
[0001] The present invention generally relates to material recovery technology. More particularly, the present invention relates to an environment friendly method and system to recycle and recover value-added materials from electronic and non-electronic wastes, particularly photovoltaic modules (PV modules).
BACKGROUND:
[0002] Now a days to protect the environment, most of the developing countries are generating energy from naturally available resources. One of such utilization of natural resource to generate electricity is solar photovoltaic modules or cells which use direct sunlight to generate direct current energy. Such photovoltaic modules comprise an aluminum frame to hold the photovoltaic modules in a place, a junction box, a silicon wafers, an EVA encapsulant to provide adhesion between cells, a metal connector, a glass, and a back sheet. These modules do not emit any harmful radiations and does not require fuel for its operation. Few of the major drawbacks of this photovoltaic module is the less energy generation as it converts only 17-25% of the energy, its dismantling process, and the discarding process of the damaged modules.
[0003] Several countries have taken steps to reduce this electronic waste by recycling and recovering of valuable materials from the waste. Such methods are thermal recycling method, laser recycling methods and mechanical recycling methods. In the thermal recycling methods, the PV module is placed in a furnace reservoir and heated to a temperature above 400 ° C for a predefined period of time. For example, United States Patent Application Number ‘995 to “Bohland et.al.,” entitled “Recycling Silicon Photovoltaic Modules” discloses a method for recycling crystalline silicon photovoltaic modules using thermal energy by heating the module in an inert atmosphere.
[0004] But the disadvantage of thermal recycling process is that it will generate harmful gaseous emission and CO2 emission to the environment during evaporation.
[0005] The next method is the cleaning of silicon substrates using laser recycling method, after the PV module is separated from the photovoltaic cells. This process yields pure silicon substrate, but it is an expensive method and is not considered efficient. The mechanical method is used to recycle complete photovoltaic modules, where the modules are crushed to desired sizes by a mechanical crusher. This process crushes the back layer and the EVA layer. However, it is difficult to find the suitable device for crushing.
[0006] None of the methods described in the prior art disclose about the eco-friendly method for obtaining valuable products from the electronic wastes like photovoltaic modules in a cost-effective manner.
[0007] Hence there is a need to develop a simple, safe, efficient, and environmentally friendly method to recover valuable materials like ethylene-vinyl acetate from other components from the discarded waste materials.

SUMMARY:
[0008] The primary objective of the present invention is to provide a simple method for recovering value added materials from electronic and non-electronic wastes, particularly from photovoltaic modules (PV modules).
[0009] Another objective of the present invention is to provide an efficient method which uses both mechanical and chemical techniques for the removal of the value-added materials, without polluting the environment, removes value-added material in an environment friendly manner.
[0010] Yet another objective of the present invention is to provide a cost-effective method and system where the chemical used for the material recovery is recycled in closed loop manner. Thus, the method and system reduce the cost of recycling electronic and non-electronic wastes using new solvent every time.
[0011] Still another objective of the present invention is to provide a unique recyclable method for recycling of solar cells based on photovoltaic modules to recover most of its components.
[0012] To achieve the above objectives, the present invention provides with a method for recovering materials like ethylene vinyl acetate (EVA) from waste comprising the steps of, shredding and crushing of wastes into small pieces, immersing the crushed pieces into first solvent at a first treatment condition, where the first solvent treatment allows to swell and solubilize the ethylene-vinyl acetate to solubilize EVA, separating the hard particles from the solubilized EVA, diluting the solubilized EVA with a second solvent at a second treatment condition, where the second solvent treatment decreases the viscosity of the solubilized EVA, and recovery of materials like ethylene-vinyl acetate and the used first and second organic solvents using vacuum assisted rotary evaporators, distillation etc.,
[0013] According to another aspect of the present invention, a system for recovering materials like ethylene-vinyl acetate (EVA) from waste comprising a shredding or crushing unit for shredding and mechanical crushing of waste material into smaller pieces of 2-5mm sizes, one or more solvent tanks for treating the crushed small pieces of waste using one or more solvents at one or more treatment conditions which enables the soluble materials present in the waste gets dissolved in the one or more solvents, and a recovering unit for recovering the materials and one or more solvents using evaporation and condensation techniques.
[0014] According to the present invention, the first solvent is an organic solvent selected at least one from the group consisting of tetrahydrofuran, dimethyl formamide, chloroform, DMSO and others.
[0015] According to the present invention, the second solvent is volatile solvents selected from the group comprising of toluene, benzene, xylene, and other volatile solvents or combinations thereof.
[0016] According to the present invention, the solubilization ratio of the crushed pieces to the first solvent is selected from any one of the ratios comprising of 1:5 or 1:10.
[0017] According to one embodiment of the present invention, the hard particles comprise aluminium frame, glass, silicon wafers, large metal contacts, white back sheets and other components present in the electronic waste. According to another embodiment, the hard particles comprise zipper, buttons, and other non-degradable materials.
[0018] According to one embodiment of the present invention, the first treatment condition comprising a treatment duration ranges between 1 to 3 hours and a treatment temperature ranges between 20-35 degrees.
[0019] According to one embodiment of the present invention, the second treatment condition comprising a treatment duration ranges between 0 to 3 hours and a treatment temperature ranges between 20-35 degrees.
[0020] According to the present invention, the first solvent and second solvent are added in any one of the following ratios selected from 1:5, 1:10, 1:20 and 1:30.
[0021] According to the present invention, the waste is an electronic waste and non-electronic wastes containing EVA as valuable material.
[0022] According to the present invention, the electronic waste is a photovoltaic module like solar panels and conductive sensors comprising EVA polymers. However, the present invention is not only limited to electronic waste but also includes sensors, cases or bags containing EVA polymer, shoes, or other material made up of EVA polymer materials.
[0023] Thus, the advantages of the present invention including but not limited to a simple and environmentally friendly method and system for the recovery and recycle of the materials like ethylene-vinyl acetate from the discarded and damaged electronic items containing EVA polymer like solar panels, sensor and from the electronic items cases.

DESCRIPTION OF THE DRAWINGS:
[0024] The foregoing and other features and advantages of the invention will be more fully understood from the following description made with reference to the drawings.
[0025] FIG. 1 illustrates a flowchart representing the steps involved in the method for recovering ethylene-vinyl acetate from electronic wastes and non-electronic wastes according to the present invention.
[0026] FIG. 2 illustrates a schematic diagram showing a system for recovering ethylene-vinyl acetate from the electronic waste according to one exemplary embodiment of the present invention.
[0027] FIG. 3 shows an image of a damaged photovoltaic module having damaged glass and silicon wafer according to one exemplary embodiment of the present invention.
[0028] FIG. 4 shows an image of a crushed and shredded photovoltaic module including around 50% glass having the silicon sandwiched in EVA layer according to one exemplary embodiment of the present invention.
[0029] FIG. 5 shows an image of a crushed and shredded photovoltaic module including around 50% glass having the silicon sandwiched in EVA layer according to one exemplary embodiment of the present invention.

DETAILED DESCRIPTION:
[0030] Aspects of the present invention are best understood by reference to the description set forth herein. All the aspects described herein will be better appreciated and understood when considered in conjunction with the following descriptions. It should be understood, however, that the following descriptions, while indicating preferred aspects and numerous specific details thereof, are given by way of illustration only and should not be treated as limitations. Changes and modifications may be made within the scope herein without departing from the spirit and scope thereof, and the present invention herein includes all such modifications.
[0031] Several aspects of the present invention are disclosed herein. It is to be understood that these aspects may or may not overlap with one another. Thus, part of one aspect may fall within the scope of another aspect, and vice versa. Each aspect is illustrated by a number of embodiments, each of which in turn, can include one or more specific embodiments. It is to be understood that the embodiments may or may not overlap with each other. Thus, part of one embodiment, or specific embodiments thereof, may or may not fall within the ambit of another, or specific embodiments thereof, and vice versa.
[0032] A broad framework of the principles will be presented by describing various embodiments of this invention using exemplary aspects. The terms "one embodiment" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. For clarity and ease of description, each aspect includes only a few embodiments. Different embodiments from different aspects may be combined or practiced separately, to design a customized process or product depending upon application requirements. Many different combinations and sub-combinations of a few representative processes or structures shown within the broad framework of this invention, that may be apparent to those skilled in the art but not explicitly shown or described, should not be construed as precluded.
[0033] The present invention relates to a simple, environmentally friendly method and system to recover materials like ethylene vinyl acetate polymer encapsulant from the damaged solar panel by closed-loop recycling process. The method developed is a physical solvent-based method having no chemical reaction resulting in swelling of ethylene-vinyl acetate from the photovoltaic module to liberate the attached components.
[0034] Definitions:
[0035] Reference to the term “chemical method” as disclosed herein refers to a process of extracting value-added materials like ethylene-vinyl acetate from electronic waste using one or more chemical solvents. The chemical solvents are selected from the organic solvents, volatile solvents, or combinations thereof.
[0036] Reference to the term “ethylene vinyl acetate” (otherwise known as EVA) as disclosed herein is an encapsulant that is used in the photovoltaic module to protect the solar cells. In general, photovoltaic cells are multilayered structure, in which the solar cells are arranged in between the ethylene-vinyl acetate encapsulation. In some cases, the solar cells are further covered with polymeric sheets. Such Ethylene-vinyl acetate encapsulation protects the solar cells from natural weather, ultraviolet rays from the sunlight and it also provides mechanical strength. This ethylene-vinyl acetate is recovered from the discarded wastes and the recycled for making other products.
[0037] Reference to the term “material” (otherwise known as value-added material) as disclosed herein refers to a value-added product or valuable product obtained from the discarded waste. According to the present invention, the material is ethylene-vinyl acetate (EVA) polymer encapsulant.
[0038] Reference to the term “physical method” as disclosed herein refers to a process of mechanical crushing of electronic wastes into small pieces.
[0039] Reference to the term “shredding or crushing unit” as disclosed herein refers to any device or apparatus that is used for reducing the size of the materials by means of shredding and crushing. According to the present invention, the shredding and crushing is performed by any of the machines like single or double shaft shredder, crusher, pulverizing unit or other machines that are known in the prior art.
[0040] Reference to the term “recovery” as disclosed herein refers to a method or system for separating the value-added material from the waste materials. More particularly, the term recovery represents that the removal of ethylene-vinyl acetate (EVA) from the discarded waste materials. using physical and chemical methods.
[0041] Reference to the term “recovery of solvents” as disclosed herein refers to a processing technique to recover or separate the used mixture of solvents by evaporation. The evaporation is carried out using various evaporator, dryer, or rotary evaporator. The solvent mixture that is used for recovering value-added material may comprise a mixture of solvents with different boiling points. Such solvents are separated using evaporation techniques followed by condensation, where the solvents are separated based on their boiling points and leaving the value-added material.
[0042] Reference to the term “waste” as disclosed herein refers to any material containing ethylene-vinyl acetate (EVA) polymer, copolymer or homopolymer that is discarded. Such materials can be selected from electronic wastes containing EVA polymers like solar module, photovoltaic module, sensors, and non-electronic wastes containing EVA like cases, bags, flexible bags and cases, shoes and other materials comprising EVA as one of its ingredients.
[0043] According to one aspect of the present invention, it provides a method for recovering materials like ethylene-vinyl acetate (EVA) from waste comprising the steps of, shredding and crushing of wastes to form small pieces of wastes, immersing the crushed small pieces into first solvent at a first treatment condition, which allows to swell and solubilize the ethylene-vinyl acetate thereby forming solubilized material having high viscosity, separating the hard particles from the solubilized material, diluting the solubilized material with a second solvent at a second treatment condition to decrease the viscosity of the solubilized material, and recovery of first and second organic solvents and valuable materials like EVA through evaporation and condensation techniques.
[0044] Referring to FIG. 1, the present invention describes the method of recovering value added materials preferably ethylene-vinyl acetate from the electronic wastes and non-electronic wastes (100), wherein the steps involved in the method are explained in detail below.
[0045] The first step (S110) is to mechanically crush and shred the electronic wastes and non-electronic wastes into small pieces of 2-5mm sized particles. These micro or nano sized electronic and non-electronic waste particles increases the area of exposure for further solvents treatment and makes efficient swelling of EVA. Contrastingly, the large and whole electronic wastes require more space and larger size processing equipment and thus increases the cost of operation.
[0046] In the second step (S120), these small particles are immersed in a reservoir containing a first solvent at a first treatment condition to achieve swelling, peeling and solubilization of ethylene-vinyl acetate encapsulant layer from the hard particles. in one embodiment, the treatment is done at an ambient temperature for 30 minutes with gentle stirring. These solvents result in the separation of various components by specifically swelling and solubilizing EVA.
[0047] In the third step (S130), the hard particles are separated from the solubilized ethylene-vinyl acetate and the first solvent by physical, non-solvent, or manual means like density-based separation. The hard particles are glass, silicon wafers, large metal contacts, white back sheets and other physical components that are present in the electronic waste other than EVA polymer layer. In case of non-electronic wastes like shoes or cases, the hard particles are like rubber, zipper, button, or other parts of shoes or cases other than the EVA material.
[0048] In the step (S140), the solubilized EVA is alone diluted at an ambient temperature with a second solvent at a specific ratio under second treatment condition. For example, one portion of the first solvent comprising solubilized EVA is diluted with ten portions of the second solvent. The EVA polymer after swelling becomes viscous in nature, so the solubilized, viscous EVA is diluted for a predefined time with second solvent at second treatment conditions or at ambient temperature to reduce the viscosity of solubilized EVA. This helps in better separation of EVA to obtain a highly pure EVA product with lesser particle binding.
[0049] In the final step (S150), the solvent used in the previous steps are recovered. The recovery process is done by rotary evaporator to separate the solvent used and the EVA. In general, the second solvent (e.g., toluene) having a boiling point of 110 ? and the first solvent (e.g., THF) having around 66 ?. While evaporation the first solvent (e.g., THF) is recovered first, then further raising the temperature the second solvent (e.g., toluene) is recovered leaving EVA behind in a molten state or gel form. However, the recovery can also be done by other methods that are well known in the prior art. Further, the recovered EVA product can be recycled back to produce films and the recovered solvents are recycled back in a circular to reusage of the same solvent for the next cycle of separation. The EVA recovered by this method described in the present invention is collected in the form of either solid or liquid at higher temperature and further the separated EVA is used to prepare films after casting in some molds.
[0050] According to another aspect of the present invention, a method for recovering materials from the waste using single solvent. The method comprising the steps of shredding and crushing of discarded wastes to form small pieces of wastes, immersing the crushed pieces into solvent at a specific treatment condition that allows to swell and solubilize the materials, where the solubilized materials having high viscosity, separating the hard particles from the solubilized material, and recovery of organic solvents and the material like EVA from the chemical solvent treatment tanks.
[0051] According to another aspect of the present invention, a method for recovering materials from the waste using multiple organic or volatile solvents. The method comprising the steps of shredding and crushing of discarded wastes to form small pieces of wastes, immersing the crushed pieces into a solvent mixture in a specific ratio at a specific treatment condition that allows to swell and solubilize the materials, where the solubilized materials having high viscosity, separating the hard particles from the solubilized material, and recovery of organic solvents and the material like EVA from the chemical solvent treatment tanks.
[0052] According to the present invention, the first solvent is an organic solvent which is at least one selected from the group consisting of tetrahydrofuran, dimethyl formamide, chloroform, DMSO, or combinations thereof.
[0053] According to the present invention, the second solvent is volatile solvents like toluene, benzene, xylene, and other volatile solvents or combinations thereof.
[0054] In one embodiment, the method of the present invention uses only one solvent. In another embodiment, the method of the present invention uses more than one solvent. In yet another embodiment, the method of the present invention uses a mixture of two or more solvents in an appropriate dilution ratio.
[0055] According to one embodiment of the present invention, the ratio of first solvent to second solvent is 1:30. The first solvent contains the solubilized value-added material. In one embodiment, the ratio of first solvent to second solvent is 1:5. In another embodiment, the ratio of first solvent to second solvent is 1:10. In another embodiment, the ratio of first solvent to second solvent is 1:20. In another embodiment, the ratio of first solvent to second solvent is 1:30.
[0056] More specifically in one embodiment, the ratio of the first solvent comprising solubilized material to the second solvent is 1:1. In another embodiment, the ratio is 1:2. In another embodiment, the ratio is 1:3. In another embodiment, the ratio is 1:4. In another embodiment, the ratio is 1:5. In another embodiment, the ratio is 1:6. In another embodiment, the ratio is 1:7. In another embodiment, the ratio is 1:8. In another embodiment, the ratio is 1:9. In another embodiment, the ratio is 1:10. In another embodiment, the ratio is 1:11. In another embodiment, the ratio is 1:12. In another embodiment, the ratio is 1:13. In another embodiment, the ratio is 1:14. In another embodiment, the ratio is 1:15. In another embodiment, the ratio is 1:16. In another embodiment, the ratio is 1:17. In another embodiment, the ratio is 1:18. In another embodiment, the ratio is 1:19. In another embodiment, the ratio is 1:20. In another embodiment, the ratio is 1:21. In another embodiment, the ratio is 1:22. In another embodiment, the ratio is 1:23. In another embodiment, the ratio is 1:24. In another embodiment, the ratio is 1:25. In another embodiment, the ratio is 1:26. In another embodiment, the ratio is 1:27. In another embodiment, the ratio is 1:28. In another embodiment, the ratio is 1:29. In another embodiment, the ratio is 1:30.
[0057] According to one embodiment of the present invention, the solubilization ratio of the material like EVA to the first solvent is defined in w/w. For example, 1g weight of electronic and non-electronic wastes to 5-10 g weight of the first solvent, preferably 5g. Hence, the solubilization ratio is selected in any one from the group comprising of 1:5 to 1:10, preferably 1:5.
[0058] According to one embodiment of the present invention, the first treatment condition comprising a treatment duration ranges between 1 to 3 hours and a treatment temperature ranges between 20-35 degrees.
[0059] According to one embodiment of the present invention, the second treatment condition comprising a treatment duration ranges between 0 to 3 hours and a treatment temperature ranges between 20-35 degrees.
[0060] According to one embodiment of the present invention, the first solvent treatment temperature is 20 degrees. In another embodiment, the first solvent treatment temperature is 21 degrees. In another embodiment, the first solvent treatment temperature is 22 degrees. In another embodiment, the first solvent treatment temperature is 23 degrees. In another embodiment, the first solvent treatment temperature is 24 degrees. In another embodiment, the first solvent treatment temperature is 25 degrees. In another embodiment, the first solvent treatment temperature is 26 degrees. In another embodiment, the first solvent treatment temperature is 27 degrees. In another embodiment, the first solvent treatment temperature is 28 degrees. In another embodiment, the first solvent treatment temperature is 29 degrees. In another embodiment, the first solvent treatment temperature is 30 degrees. In another embodiment, the first solvent treatment temperature is 31 degrees. In another embodiment, the first solvent treatment temperature is 32 degrees. In another embodiment, the first solvent treatment temperature is 33 degrees. In another embodiment, the first solvent treatment temperature is 34 degrees. In another embodiment, the first solvent treatment temperature is 35 degrees.
[0061] According to one embodiment of the present invention, the second solvent treatment temperature is 20 degrees. In another embodiment, the second solvent treatment temperature is 21 degrees. In another embodiment, the second solvent treatment temperature is 22 degrees. In another embodiment, the second solvent treatment temperature is 23 degrees. In another embodiment, the second solvent treatment temperature is 24 degrees. In another embodiment, the second solvent treatment temperature is 25 degrees. In another embodiment, the second solvent treatment temperature is 26 degrees. In another embodiment, the second solvent treatment temperature is 27 degrees. In another embodiment, the second solvent treatment temperature is 28 degrees. In another embodiment, the second solvent treatment temperature is 29 degrees. In another embodiment, the second solvent treatment temperature is 30 degrees. In another embodiment, the second solvent treatment temperature is 31 degrees. In another embodiment, the second solvent treatment temperature is 32 degrees. In another embodiment, the second solvent treatment temperature is 33 degrees. In another embodiment, the second solvent treatment temperature is 34 degrees. In another embodiment, the second solvent treatment temperature is 35 degrees.
[0062] In a preferable embodiment of the present invention, the optimum treatment temperature of first solvent is 30 degrees and the second solvent is also 30 degrees.
[0063] In one embodiment, the first and second treatment conditions are the same. In another embodiment, the first and second treatment conditions are different.
[0064] According to the present invention, the evaporation temperature of the first and second solvent recovery ranges up to 200 C. However, for the process of evaporation, the temperature may vary based on the boiling points of the first and the second solvents used for the recovery of value-added material (EVA). In one embodiment, the vacuum-assisted rotary evaporator reduces the boiling point of the solvent mixtures. Hence, the present invention is not limited only to the specified solvents, but it also covers other organic and volatile solvents that are known very well in the prior art.
[0065] According to the present invention, the waste is an electronic waste and non-electronic wastes containing EVA as valuable material.
[0066] According to the present invention, the electronic waste is a damaged, discarded, or end-of-life, silicon-based photovoltaic modules like solar panels and conductive sensors comprising EVA polymers. However, the present invention is not limited only to electronic waste but also includes non-electronic wastes consisting of EVA polymers like cases or bags, shoes or other material that is made up of EVA polymer material.
[0067] According to the present invention, the material or value-added material is ethylene-vinyl acetate (EVA).
[0068] According to the present invention, the efficiency of recovering ethylene-vinyl acetate is 80 to 99% or more.
[0069] According to another aspect of the present invention, a system for recovering materials like ethylene-vinyl acetate (EVA) from waste comprising a shredding or crushing unit for shredding and mechanical crushing of the waste material into small pieces of 2-5mm sizes, one or more solvent tank unit for treating the crushed pieces of waste using one or more solvents at a specific treatment condition, where the materials present in the waste gets dissolved in the one or more solvents, and a recovering unit for recovering the materials and one or more solvents using evaporation and condensation techniques.
[0070] According to one embodiment of the present invention, a perforated tank is configured to remove the hard particles after solubilizing the crushed materials into solvents. The perforated tank is provided with plurality of pores/mesh like structure which enables the transfer of hard particles after EVA material solubilization in one or more solvents before evaporation.
[0071] According to another aspect of the present invention, FIG. 2 illustrates a schematic diagram disclosing a system for recovering value-added materials from the electronic waste. The system (200) comprising a shredding or crushing unit (210) for crushing of electronic waste into smaller pieces, a one or more solvent tanks (220) for immersing the crushed pieces of electronic waste in one or more solvents at one or more treatment conditions, and a recovery unit (230) for recovering the one or more solvents used for the recovery of materials by means of evaporation and condensation, where the material is left behind.
[0072] The shredding or crushing unit (210) is for shredding and crushing the electronic wastes like photovoltaic modules into tiny pieces and further into powdered form. The size of the pieces ranging between 2-5 mm. the electronic wastes are shredded and crushed by any kind of mechanical crushers. Shredders or pulverizing units that are well known in the prior art.
[0073] The one or more solvent tank (220) for immersing the crushed pieces of electronic waste in one or more solvents at one or more treatment conditions where the value-added material present in the crushed pieces of waste gets dissolved in the first solvent thus forming solubilized materials with high viscosity. The viscous material is further processed to remove the hard particles like glass pieces, glass, silicon wafers, large metal contacts, white back sheets and other physical components that are present in the electronic waste other than EVA polymer layer. These hard particles are separated by physical, non-solvent, or manual means like density-based separation. Further, one or more solvent tank comprising solubilized material, is diluted using a second solvent at a second treatment condition, where the viscosity of the solubilized materials is decreased to achieve the better separation of value-added materials.
[0074] One or more perforation tank (not shown) is connected with one or more solvent tanks, where the hard particles are removed using this perforation tank. In one embodiment, a mesh is used to remove hard particles from the EVA material solubilized solvent tank.
[0075] A recovery unit (230) for recovering the one or more solvents used for solubilizing materials, by evaporation and condensation methods. The used solvent mixture is separated based on the different boiling points. The evaporation unit is vacuum assisted rotary evaporation with adjustable temperature controls. Upon evaporation in the evaporation unit the solvents are separated at their respective boiling temperatures and recovered using condensation techniques, thus leaving the value-added material in the one or more solvent tanks in the molten state or gel form. The evaporation temperature of the first and second solvent recovery ranges up to 200 C or depends upon the evaporation temperature of the one or more solvents used according to the present invention. Further, the recovered solvents can be recycled back in a closed loop manner for next cycle of recovery of value-added materials.
[0076] According to yet another aspect of the present invention, the system comprising a shredding and crushing unit for crushing of waste into smaller pieces, a one solvent tank for immersing the crushed pieces of waste in one solvent at a treatment condition to form a solubilized material having high viscosity, and a recovery unit for recovering the solvent used for the recovery of materials by means of evaporation and condensation, where the material is left behind. In one embodiment, the hard particles are removed from the solubilized material before entering the recovery unit.
[0077] According to one embodiment of the present invention, the one or more solvents is a mixture of first and second solvent in a different concentration.
[0078] In another embodiment, the system of the present invention uses only one solvent. In another embodiment, the system of the present invention uses more than one solvent. In yet another embodiment, the system of the present invention uses a mixture of two or more solvents in an appropriate dilution ratio.
[0079] According to one embodiment of the present invention, the first solvent is an organic solvent which is at least one selected from the group consisting of tetrahydrofuran, dimethyl formamide, chloroform, DMSO, or combinations thereof.
[0080] According to one embodiment of the present invention, the second solvent is volatile solvents like toluene, benzene, xylene, and other volatile solvents or combinations thereof.
[0081] According to one embodiment of the present invention, the ratio of first solvent to second solvent is 1:30. The first solvent containing the solubilized value-added material. In one embodiment, the ratio of first solvent to second solvent is 1:5. In another embodiment, the ratio of first solvent to second solvent is 1:10. In another embodiment, the ratio of first solvent to second solvent is 1:20. In another embodiment, the ratio of first solvent to second solvent is 1:30.
[0082] More specifically in one embodiment, the ratio of the first solvent comprising solubilized material to the second solvent is 1:1. In another embodiment, the ratio is 1:2. In another embodiment, the ratio is 1:3. In another embodiment, the ratio is 1:4. In another embodiment, the ratio is 1:5. In another embodiment, the ratio is 1:6. In another embodiment, the ratio is 1:7. In another embodiment, the ratio is 1:8. In another embodiment, the ratio is 1:9. In another embodiment, the ratio is 1:10. In another embodiment, the ratio is 1:11. In another embodiment, the ratio is 1:12. In another embodiment, the ratio is 1:13. In another embodiment, the ratio is 1:14. In another embodiment, the ratio is 1:15. In another embodiment, the ratio is 1:16. In another embodiment, the ratio is 1:17. In another embodiment, the ratio is 1:18. In another embodiment, the ratio is 1:19. In another embodiment, the ratio is 1:20. In another embodiment, the ratio is 1:21. In another embodiment, the ratio is 1:22. In another embodiment, the ratio is 1:23. In another embodiment, the ratio is 1:24. In another embodiment, the ratio is 1:25. In another embodiment, the ratio is 1:26. In another embodiment, the ratio is 1:27. In another embodiment, the ratio is 1:28. In another embodiment, the ratio is 1:29. In another embodiment, the ratio is 1:30.
[0083] According to one embodiment of the present invention, the solubilization ratio of the material like EVA to the first solvent is defined in w/w. For example, 1g weight of electronic or non-electronic wastes to 5-10 g weight of the first solvent, preferably 5g. Hence, the solubilization ratio is selected any one from the group comprising of 1:5 to 1:10, preferably 1:5.
[0084] According to the present invention, the one or more treatment conditions comprise first and second treatment conditions corresponding to the first and second solvent treatments.
[0085] According to one embodiment of the present invention, the first treatment condition comprising a treatment duration ranges between 1 to 3 hours and a treatment temperature ranges between 20-35 degrees.
[0086] According to one embodiment of the present invention, the second treatment condition comprising a treatment duration ranges between 0 to 3 hours and a treatment temperature ranges between 20-35 degrees.
[0087] According to one embodiment of the present invention, the first solvent treatment temperature is 20 degrees. In another embodiment, the first solvent treatment temperature is 21 degrees. In another embodiment, the first solvent treatment temperature is 22 degrees. In another embodiment, the first solvent treatment temperature is 23 degrees. In another embodiment, the first solvent treatment temperature is 24 degrees. In another embodiment, the first solvent treatment temperature is 25 degrees. In another embodiment, the first solvent treatment temperature is 26 degrees. In another embodiment, the first solvent treatment temperature is 27 degrees. In another embodiment, the first solvent treatment temperature is 28 degrees. In another embodiment, the first solvent treatment temperature is 29 degrees. In another embodiment, the first solvent treatment temperature is 30 degrees. In another embodiment, the first solvent treatment temperature is 31 degrees. In another embodiment, the first solvent treatment temperature is 32 degrees. In another embodiment, the first solvent treatment temperature is 33 degrees. In another embodiment, the first solvent treatment temperature is 34 degrees. In another embodiment, the first solvent treatment temperature is 35 degrees.
[0088] According to one embodiment of the present invention, the second solvent treatment temperature is 20 degrees. In another embodiment, the second solvent treatment temperature is 21 degrees. In another embodiment, the second solvent treatment temperature is 22 degrees. In another embodiment, the second solvent treatment temperature is 23 degrees. In another embodiment, the second solvent treatment temperature is 24 degrees. In another embodiment, the second solvent treatment temperature is 25 degrees. In another embodiment, the second solvent treatment temperature is 26 degrees. In another embodiment, the second solvent treatment temperature is 27 degrees. In another embodiment, the second solvent treatment temperature is 28 degrees. In another embodiment, the second solvent treatment temperature is 29 degrees. In another embodiment, the second solvent treatment temperature is 30 degrees. In another embodiment, the second solvent treatment temperature is 31 degrees. In another embodiment, the second solvent treatment temperature is 32 degrees. In another embodiment, the second solvent treatment temperature is 33 degrees. In another embodiment, the second solvent treatment temperature is 34 degrees. In another embodiment, the second solvent treatment temperature is 35 degrees.
[0089] In a preferable embodiment of the present invention, the optimum treatment temperature of first solvent is 30 degrees and the second solvent is also 30 degrees.
[0090] In one embodiment, the first and second treatment condition is the same. In another embodiment, the first and second treatment conditions are different.
[0091] According to the present invention, the waste is an electronic waste or a non-electronic waste.
[0092] According to the present invention, the electronic waste is a damaged, discarded, or end-of-life, silicon-based photovoltaic modules like solar panels and conductive sensors. However, the present invention is not only limited to electronic waste but also includes cases or bags, shoes or other material that is made up of EVA polymer material.
[0093] According to the present invention, the material or value-added material is ethylene-vinyl acetate.
[0094] According to the present invention, the efficiency of recovering ethylene-vinyl acetate is 80 to 99% or more.
[0095] The invention according to aspects/embodiments stated above will hereinafter be described specifically by examples. However, it should not be construed that the invention is limited to or by them. Examples that are provided below is not only limited to the defined condition parameters like temperatures, treatment duration, solvent mixing ratio, solubilization ratio and other conditions, but also including any conditions parameters as described in the above paragraphs.
[0096] FIG. 3 to 5 show the photographs or images of the PV module processing steps according to the method of the present invention.
[0097] Example 1:
[0098] De glassed PV module is treated with a first solvent Tetrahydrofuran (THF) in an appropriate container to dissolve EVA at a temperature of 25 oC for 1 hour. After swelling, the EVA gets dissolved in THF and makes the solvent viscous. Further, the second solvent toluene is added in 1:10 ratio to the THF to decrease the viscosity at a temperature of about 25 oC for 0.5 hour. Furthermore, easy liberation of silicon wafer and glass in organic solvent under gentle stirring or ultrasonication.
[0099] Example 2:
[0100] De glassed PV module is treated with a first solvent Tetrahydrofuran (THF) in an appropriate container to dissolve EVA at a temperature of 28 oC for 1 hour. After swelling, the EVA gets dissolved in THF and makes the solvent viscous. Further, the second solvent toluene is added in 1:8 ratio to the THF to decrease the viscosity at a temperature of 28 oC for 0.5 hour. Furthermore, easy liberation of silicon wafer and glass in organic solvent under gentle stirring or ultrasonication.
[0101] Example 3
[0102] De glassed PV module is treated with a first solvent Tetrahydrofuran (THF) in an appropriate container to dissolve EVA at a temperature of 35 oC for 1.5 hours. After swelling, the EVA gets dissolved in THF and makes the solvent viscous. Further, the toluene is added in 1:15 ratio to the THF to decrease the viscosity at a temperature of 35 oC for 0.15 hour. Furthermore, easy liberation of silicon wafer and glass in organic solvent under gentle stirring or ultrasonication.
[0103] Example 4
[0104] De glassed PV module is treated with a first solvent Tetrahydrofuran (THF) in an appropriate container to dissolve EVA at a temperature of 30 oC for 2 hours. After swelling, the EVA gets dissolved in THF and makes the solvent viscous. Further, the second solvent toluene is added in 1:10 ratio to the THF to decrease the viscosity at a temperature of 30 oC for 0.16 hours. Furthermore, easy liberation of silicon wafer and glass in organic solvent under gentle stirring or ultrasonication.
[0105] Example 5
[0106] De glassed PV module is treated with a first solvent Tetrahydrofuran (THF) in an appropriate container to dissolve EVA at a temperature of 30 oC for 3 hours. After swelling, the EVA gets dissolved in THF and makes the solvent viscous. Further, the second solvent toluene is added in 1:5 ratio to the THF to decrease the viscosity at a temperature of 30 oC for 0.25 hours. Furthermore, easy liberation of silicon wafer and glass in organic solvent under gentle stirring or ultrasonication.
Table 1
Examples First solvent treatment conditions Solubilization Ratio of EVA:THF (first solvent) Ratio of THF:Toluene (first solvent:Second solvent) Second solvent treatment conditions. Recovery of EVA (%)
Time (Hr) Temp (?) Time (Hr) Temp (?)
1 1 25 1:10 1:10 0.5 25 95
2 1 28 1:12 1:8 0.5 28 90
3 1.5 35 1:15 1:15 0.15 35 98
4 2 30 1:10 1:10 0.16 30 85
5 3 30 1:20 1:5 0.25 30 80

[0107] Table 1 represents the correlation between the different treatment parameters/conditions involved according to the present invention and the recovery amount of EVA in %.

[0108] Comparative Example:
[0109] Generally photovoltaic modules are recycled by various techniques and process. One of those traditional practice is by thermal treatment. Conventionally, the photovoltaic cells comprising solar cells, one or more polymers and glass substrates are recycled by heating modules under an inert atmosphere as disclosed herein by the United States Patent ‘995 to “Bohland et.al.,”. While heating the photovoltaic module, the EVA polymeric layers encapsulating the solar cells are thermally decomposed leaving only the solar cells and also carbon dioxide is liberated during this process.
[0110] However, the method and system of the present invention recovers value-added material like ethylene-vinyl acetate from wastes with an efficiency of 80-99% as provided in table 1 without using thermal treatment for burning the waste material and without liberating carbon dioxide gas unlike conventional method thereby controlling environmental pollution. Further, the method and system of the present invention is considered as a cost-effective method, where the chemicals or solvents used in the present invention is recovered and reused for next cycle of extraction and recovery of the value-added materials like ethylene-vinyl acetate from the electronic and non-electronic wastes. Thereby reducing the cost of using a new solvent for the next cycle of value-added material recovery process from wastes. Contrastingly, the traditional methods are not considered expensive than that of the present invention as it requires a separate chamber or an apparatus for thermal treatment and the reaction conditions require extremely high temperature of about 480° C. to about 540° C. However, the present invention does not involve the usage of high temperatures.
[0111] The ethylene-vinyl acetate (EVA) is recovered from the discarded electronic waste, and it can be recycled back to form new EVA polymer products which can be used in various applications like fabricating electronic devices, photovoltaic modules, creating flexible cases and bags for various products, shoes, record turntable mats, handle grips, vacuum cleaner hoses, food and beverage tubing, drug delivery systems and other applications.
[0112] Further, the solvents or mixture of the solvents used according to the present invention can be recovered and reused for the same process of extracting and recovering ethylene-vinyl acetate from the electronic and non-electronic wastes in the next cycle. This makes the present invention a cost-effective and sustainable solution.
[0113] Thus, the advantages of the present invention including but not limited to a simple, economical, and environmentally friendly method to recover ethylene-vinyl acetate from discarded wastes like photovoltaic module. Further, the method of the present invention is a combination of physical and chemical method which is considered as safe for the environment and does not use higher pyrolytic temperatures, unlike the conventional thermal methods that generates smoke and gases like carbon dioxides, etc. Further, this method is a closed-loop design to process the waste PV panels and recover every component by keeping environmental concern on top priority.
[0114] Although the invention has been described with regard to its embodiments, specific embodiments and various examples, which constitute the best mode presently known to the inventors, it should be understood that various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the scope of the invention as set forth in the claims appended hereto.

REFERENCE NUMERALS:
[0115] 100 – Method for recovery of EVA
[0116] S110 – Shredding and crushing
[0117] S120 – Immersion in first solvent
[0118] S130 – Separation of hard particles
[0119] S140 – Immersion in second solvent
[0120] S150 – Recovery of solvents
[0121] 200 – System
[0122] 210 – Shredding or crushing unit
[0123] 220 – One or More Solvent tanks
[0124] 230 – Recovery Unit
,CLAIMS:1. A method (100) for recovering materials from waste, comprising the steps of:
a. shredding and mechanical crushing of wastes to obtain crushed waste pieces in step S110;
b. immersing the crushed pieces into first solvent at a first treatment condition in step S120, wherein the first solvent allows to swell and solubilize the material to form a solubilized material having high viscosity;
c. separating hard particles from the solubilized material in step S130;
d. diluting the solubilized material with a second solvent at a second treatment condition in step S140 to decrease the viscosity of the solubilized material; and
e. recovering the first and second solvents using evaporation and condensation in step S150 followed by recovering the materials.
2. The method (100) as claimed in claim 1, wherein the first solvent is an organic solvent selected from the group comprising of tetrahydrofuran, dimethyl formamide, chloroform, DMSO, or combinations thereof.
3. The method (100) as claimed in claim 1, wherein the second solvent is a volatile solvent selected from the group comprising of toluene, benzene, xylene, other volatile solvents, or combinations thereof.
4. The method (100) as claimed in claim 1, wherein the solubilization ratio of the crushed pieces to the first solvent is selected from any one of the ratios comprising of 1:5 or 1:10.
5. The method (100) as claimed in claim 1, wherein the ratio of first solvent to second solvent is 1:5.
6. The method (100) as claimed in claim 1, wherein the ratio of first solvent to second solvent is 1:10.
7. The method (100) as claimed in claim 1, wherein the ratio of first solvent to second solvent is 1:20.
8. The method (100) as claimed in claim 1, wherein the ratio of first solvent to second solvent is 1:30.
9. The method (100) as claimed in claim 1, wherein the first treatment condition comprising a treatment duration ranges between 1 to 3 hours and treatment temperature ranges between 20-35 degrees.
10. The method (100) as claimed in claim 1, wherein the second treatment condition comprising a treatment duration ranges between 0 to 3 hours and treatment temperature ranges between 20-35 degrees.
11. The method (100) as claimed in claim 1, wherein the waste is an electronic waste or a non-electronic waste.
12. The method (100) as claimed in claim 11, wherein the electronic waste is a photovoltaic module.
13. The method (100) as claimed in claim 1, wherein the material is ethylene-vinyl acetate (EVA).a
14. A system (200) for recovering value-added materials from wastes, comprising:
a. a shredding or crushing unit (210) for crushing of wastes into smaller pieces;
b. one or more solvent tanks (220) for immersing the crushed pieces of wastes in one or more solvents at one or more treatment conditions, wherein the one or more solvents is a mixture of first and second solvent in a different concentration; and
c. a recovery unit (230) for recovering the one or more solvents used for the recovery of materials by means of evaporation and condensation, wherein the value-added material is left behind.
15. The system (200) as claimed in claim 14, wherein the first solvent is an organic solvent selected from the group comprising of tetrahydrofuran, dimethyl formamide, chloroform, DMSO, or combinations thereof.
16. The system (200) as claimed in claim 14, wherein the second solvent is a volatile solvent selected from the group comprising of toluene, benzene, xylene, other volatile solvents, or combinations thereof.
17. The system (200) as claimed in claim 14, wherein the solubilization ratio of the crushed pieces to the first solvent is selected from any one of the ratios comprising of 1:5 or 1:10.
18. The system (200) as claimed in claim 14, wherein the ratio of the first solvent to the second solvent is selected from any of 1:5, 1:10, 1:20 and 1:30.
19. The system (200) as claimed in claim 14, wherein the one or more treatment conditions comprising a treatment duration ranges between 0 to 3 hours and a treatment temperature ranges between 20-35 degrees.
20. The system (200) as claimed in claim 14, wherein the waste is an electronic waste or a non-electronic waste.
21. The system (200) as claimed in claim 20, wherein the electronic waste is a photovoltaic module.
22. The system (200) as claimed in claim 14, wherein the material is ethylene-vinyl acetate (EVA).