Separation and recovery method of aluminum-plastic composite packaging material

Abstract

The application provides a separation and recovery method of aluminum-plastic composite packaging material, and belongs to the field of resource recycling. The method comprises the following steps: crushing and grinding waste aluminum-plastic composite packaging materials to obtain pretreated materials; mixing a deep eutectic solvent with an interfacial penetration aid to obtain a separation liquid; performing ultrasonic-assisted interfacial separation on the mixture of the pretreated materials and the separation liquid to obtain dissociated mixed materials; sequentially performing eddy current separation and frictional electrostatic separation on the dissociated mixed materials to separate aluminum materials and plastic particles; and recycling used choline chloride and ethylene glycol by filtration separation and reduced pressure distillation, and obtaining recyclable regenerated deep eutectic solvent after proportioning. The deep eutectic solvent is composed of choline chloride and ethylene glycol, and the interfacial penetration aid is glycolic acid. The application realizes efficient interfacial dissociation and resource recovery of aluminum foil and plastic matrix in aluminum-plastic composite packaging material through chemical selectivity and physical strengthening synergy.

Description

Technical Field

[0001] This application relates to the field of resource recycling technology, and in particular to a method for separating and recycling aluminum-plastic composite packaging materials. Background Technology

[0002] Aluminum-plastic composite packaging materials are widely used in the pharmaceutical, food, and daily chemical industries due to their good barrier properties, lightweight, and portability. However, waste aluminum-plastic packaging is difficult to degrade naturally. The aluminum foil and plastic layer are tightly bonded together with polyurethane adhesive, acrylic adhesive, or hot melt adhesive, which presents significant shortcomings in conventional recycling technologies.

[0003] Existing recycling technologies are mainly divided into two categories: physical sorting methods and traditional chemical methods. Physical methods employ crushing, grinding, eddy current, and electrostatic separation processes, but these methods are insufficient for the dissociation of the highly bonded aluminum-plastic interface, resulting in low separation purity and severe fine powder inclusion, thus failing to achieve high-value resource recovery. Traditional chemical methods achieve separation by dissolving aluminum foil through strong alkali corrosion, but this method suffers from drawbacks such as the inability to recover aluminum resources, damage to the plastic substrate by strong alkali, and the generation of highly saline-alkaline wastewater, making it impossible to achieve bidirectional, non-destructive, and green recycling of aluminum and plastic. Therefore, how to achieve efficient interfacial dissociation and resource recovery of aluminum foil and the plastic matrix in aluminum-plastic composite packaging materials is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application provides a method for separating and recycling aluminum-plastic composite packaging materials to solve the following technical problem: how to achieve efficient interfacial dissociation and resource recycling of aluminum foil and plastic matrix in aluminum-plastic composite packaging materials.

[0005] This application provides a method for separating and recycling aluminum-plastic composite packaging materials, the method comprising: Waste aluminum-plastic composite packaging materials are crushed and ground to obtain pre-treated materials. The deep eutectic solvent and the interfacial permeation aid are mixed to obtain the separation solution; The mixture of the pretreated material and the separation liquid is subjected to ultrasonic-assisted interfacial separation to obtain a dissociated mixture. The dissociated mixture was subjected to eddy current separation and triboelectric separation in sequence to separate aluminum material and plastic particles. The components of the separated liquid after use are recovered by filtration and vacuum distillation, and then reconstituted to obtain a recyclable deep eutectic solvent. The deep eutectic solvent is composed of choline chloride and ethylene glycol, and the interfacial penetration aid is glycolic acid.

[0006] Optionally, the crushing process involves crushing the waste aluminum-plastic composite packaging material into particles of 10mm to 20mm. The grinding process involves grinding to a depth of less than 5 mm.

[0007] Optionally, the molar ratio of choline chloride to ethylene glycol is 1:(1.5 to 2.5).

[0008] Optionally, the mass of the glycolic acid is 5% to 8% of the total mass of the separated liquid.

[0009] Optionally, the pH value of the separation solution is 5.0 to 7.0.

[0010] Optionally, the ultrasound-assisted interface separation includes the following parameters: temperature of 40℃~60℃, ultrasound power of 100W~150W, and processing time of 5min~10min.

[0011] Optionally, the mass solid-liquid ratio of the pretreated material to the separated liquid is 1:(2-2.5).

[0012] Optionally, the magnetic roller for eddy current separation operates at a frequency of 200Hz to 500Hz; The voltage for the triboelectric electrostatic separation is 50kV to 60kV.

[0013] Optionally, the distillation temperature of the vacuum distillation is 70℃~90℃, and the vacuum degree is -0.07MPa~-0.09MPa.

[0014] Optionally, the waste aluminum-plastic composite packaging materials include at least one of the following: pharmaceutical aluminum-plastic blister packs, food aluminum-plastic packaging films, paper aluminum-plastic Tetra Pak cartons, or aluminum-PET composite packaging.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for separating and recycling aluminum-plastic composite packaging materials. Through the synergistic effect of chemical selectivity and physical reinforcement, it achieves efficient interfacial dissociation and resource recycling of aluminum foil and plastic matrix in aluminum-plastic composite packaging materials.

[0016] The separation solution exhibits chemoselectivity in its effect on the interfacial bonding layer. This method utilizes a deep eutectic solvent composed of choline chloride and ethylene glycol as the main component of the separation solution, with glycolic acid as an interfacial penetration aid. This separation solution system selectively swells the adhesive component in the aluminum-plastic composite, causing volume swelling and a decrease in cohesive strength in the cross-linked and cured adhesive layer. It can also penetrate and disrupt the intermolecular hydrogen bonds and van der Waals forces at the interface of adhesive-free, high-temperature hot-pressed aluminum-plastic composites. The combination of the deep eutectic solvent and glycolic acid allows the separation solution to precisely weaken the interfacial bonding strength without dissolving or corroding the aluminum foil or plastic substrate.

[0017] Ultrasonic-assisted separation provides the driving force for physical dissociation and enhances mass transfer. While chemical swelling weakens the interfacial bonding forces, the cavitation effect of ultrasound generates localized high-pressure shock waves and microjets near the solid-liquid interface, applying physical dissociation to the interface that has been initially weakened but not yet completely broken. Simultaneously, ultrasonic vibration promotes continuous collisions and friction between particles, creating new exposed interfaces on the particle surfaces, thus facilitating better separation of the liquids. The synergistic effect of chemical swelling and ultrasonic dissociation allows the interfacial bonding forces to be effectively destroyed within a short processing time, achieving complete separation of aluminum foil fragments and plastic fragments.

[0018] Sufficient solid-liquid contact ensures the uniformity and adequacy of the separation process. This method mixes pretreated fine particles (below 5 mm) with the separation liquid at a mass solid-liquid ratio of 1:2 to 1:2.5. The ample liquid volume ensures good particle flowability in the reactor, allowing for uniform distribution of ultrasonic energy between the solid and liquid phases. Simultaneously, it maintains the concentration gradient of the separation liquid at the solid-liquid interface, ensuring that interfacial penetration occurs fully across the entire outer surface of each particle.

[0019] Multi-stage physical sorting and closed-loop solvent recovery achieve product purification and media regeneration. After dissociation, although aluminum foil fragments and plastic fragments are completely separated, they still coexist in the dissociated mixture. This method utilizes eddy current sorting, where aluminum generates induced eddy currents in an alternating magnetic field, resulting in a repulsive force, to achieve initial separation of aluminum and plastic. Then, triboelectric electrostatic sorting utilizes the difference in charge between aluminum and plastic for finer separation. This two-stage series connection ensures that the purity of the final aluminum and plastic particles meets the requirements for high-value recycling. The used separation liquid is filtered, separated, and regenerated by vacuum distillation, achieving the recycling of the separation media and supporting the sustainable operation of this method from a process economic perspective. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart illustrating a method for separating and recycling aluminum-plastic composite packaging materials, provided as an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0025] Figure 1 This is a schematic flowchart illustrating a method for separating and recycling aluminum-plastic composite packaging materials, provided as an embodiment of this application.

[0026] like Figure 1 As shown in the embodiment of this application, a method for separating and recycling aluminum-plastic composite packaging materials is provided, the method comprising: S1. The waste aluminum-plastic composite packaging material is crushed and ground to obtain pre-treated material; S2. Mix the deep eutectic solvent with the interfacial permeation aid to obtain the separation solution; S3. The mixture of pretreated material and separation liquid is subjected to ultrasonic-assisted interfacial separation to obtain a dissociated mixture. S4. The dissociated mixture is subjected to eddy current separation and triboelectric separation in sequence to separate aluminum and plastic particles. S5. The used separation liquid is recovered by vacuum distillation to obtain a recyclable deep eutectic solvent. The deep eutectic solvent is composed of choline chloride and ethylene glycol, and the interfacial penetration aid is glycolic acid.

[0027] It should be noted that step S1 is a physical preparation stage. Its core function is to remove the external shape constraints of waste aluminum-plastic composite packaging materials, transforming large-volume, irregularly shaped, rolled, or packaged composite materials into uniformly sized granular materials. Crushing to 10-20mm coarse particles provides a suitable feed size for subsequent grinding, while grinding to below 5mm further reduces the material size, increasing the exposed area and cross-sectional density of the aluminum-plastic composite layer. In addition, auxiliary operations such as washing, stirring, filtering, and drying before pretreatment aim to remove impurities such as labels, residues, and stains adhering to the material surface, preventing foreign matter from interfering with the efficiency of the separation liquid or contaminating the recycled products.

[0028] Step S2 involves the preparation of the separation solution. The deep eutectic solvent system formed by choline chloride and ethylene glycol creates a green solvent medium with both polarity and moderate viscosity through a hydrogen bond network between them. This system selectively swells and weakens the adhesive component in aluminum-plastic composites, causing volume swelling and a decrease in cohesive strength in the cross-linked cured adhesive layer. This results in microcracks and adhesion degradation at the bonding interface between the aluminum foil and the plastic. Furthermore, it can penetrate and disrupt the intermolecular hydrogen bonds and van der Waals forces at the interface of adhesive-free high-temperature hot-pressed aluminum-plastic composites. The addition of glycolic acid further enhances the interfacial penetration ability of this system, synergistically weakening the interfacial bonding force between the adhesive and the substrate.

[0029] Step S3 is the core operational step that synergistically couples the chemical effects of S2 with the physical external field. After the pretreated particles and the separation liquid are mixed in a specific ratio, they are placed in an ultrasonic field. The ultrasonic energy generates multiple strengthening effects at the solid-liquid interface through cavitation and mechanical vibration. Specifically, when the ultrasonic cavitation bubbles collapse near the aluminum-plastic interface, they release localized high-pressure and high-temperature shock waves, which can further separate the interfacial adhesive layer that has been initially weakened but not completely broken in S2, accelerating the swelling and penetration process. Ultrasonic vibration also promotes continuous collisions and friction between particles, creating new exposed interfaces on the particle surface, allowing for better separation of the separation liquid.

[0030] Step S4 involves multi-stage physical sorting. After drying to remove residual separation liquid, the dissociated mixture enters the physical sorting section. The logic behind the two-stage, series-connected sorting design is based on the fundamental differences in physical properties between aluminum and plastic: Eddy current sorting utilizes the induced eddy currents generated by aluminum foil fragments in an alternating magnetic field. These eddy currents interact with the applied magnetic field to generate a repulsive force, causing the aluminum fragments to be ejected along a specific trajectory, achieving coarse separation from plastic fragments. This stage has excellent ability to distinguish between metals and non-metals, but its selectivity for fine-particle or flat aluminum shavings is limited. Triboelectric electrostatic sorting utilizes the difference in polarity and charge between aluminum and plastic after triboelectric charging to achieve fine separation in a high-voltage electric field, capturing fine-particle aluminum shavings missed in the eddy current sorting. The two stages, connected in series, constitute a coarse + fine sorting hierarchy, ensuring that the purity of the final aluminum and plastic particles meets the requirements for high-value recycling.

[0031] The value of step S5 lies in both its economic efficiency and environmental friendliness. Besides the main deep eutectic solvent, the used separation liquid contains small amounts of adhesive fragments and trace impurities detached from the aluminum-plastic interface. Direct discharge of this liquid wastes solvent resources and causes organic pollution. After filtration to remove adhesives and other impurities, the separation liquid is further purified by vacuum distillation to remove ethylene glycol and water, thus achieving liquid recovery. The recovered components can be recombined and directly reused in the S2 separation liquid preparation stage. This closed-loop design allows a single batch of separation liquid to be recycled more than 12 times with a separation efficiency retention rate of no less than 96%, significantly reducing the reagent consumption cost of the separation liquid.

[0032] In some embodiments, the crushing process involves crushing the waste aluminum-plastic composite packaging material into particles of 10–20 mm. The grinding process involves grinding to a depth of less than 5mm.

[0033] Waste aluminum-plastic composite packaging material is first crushed into 10-20mm particles, then ground to below 5mm. This progressive particle size control ensures that the material has a sufficiently large specific surface area during subsequent solid-liquid contact, allowing the separation liquid to fully wet and penetrate all areas of the aluminum-plastic bonding interface. Simultaneously, the suitable particle size range prevents excessively fine particles from being difficult to capture effectively by eddy currents or electrostatic fields during the sorting process due to their light weight, thus balancing interface separation efficiency and physical sorting recovery rate. For example, the particle size of the crushed waste aluminum-plastic composite packaging material can be 10mm, 11mm, 12mm, 14mm, 15mm, 17mm, 18mm, 20mm, etc.

[0034] In some embodiments, the molar ratio of choline chloride to ethylene glycol is 1:(1.5 to 2.5).

[0035] The molar ratio of choline chloride to ethylene glycol determines the hydrogen bond network density and viscosity characteristics of the deep eutectic solvent system. Limiting the molar ratio of choline chloride to ethylene glycol to 1:(1.5–2.5) allows for the formation of a stable eutectic system while maintaining suitable fluidity. For example, the molar ratio of choline chloride to ethylene glycol can be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2.0, 1:2.2, 1:2.5, etc.

[0036] In some embodiments, the mass of glycolic acid is 5% to 8% of the total mass of the separation liquid.

[0037] By limiting the mass of glycolic acid to 5%–8% of the total mass of the separation liquid, it can function as an interfacial penetration aid. Its small-molecule bifunctional structure can effectively reduce the surface tension of the separation liquid, enhance its penetration ability into microcracks in the colloidal layer, and, in conjunction with the bulk swelling effect of the deep eutectic solvent, achieve efficient weakening of interfacial bonding forces. For example, the mass fraction of glycolic acid in the total mass of the separation liquid can be 5%, 5.4%, 5.8%, 6.2%, 6.7%, 7.1%, 7.5%, 8%, etc.

[0038] In some implementations, the pH of the separation solution is 5.0 to 7.0.

[0039] Limiting the pH of the separation solution to 5.0–7.0 ensures that it does not chemically corrode the aluminum foil substrate, nor dissolve or embrittle the plastic substrate, while maintaining the carboxyl groups in the glycolic acid in a suitable dissociated state to ensure its permeation activity. For example, the pH of the separation solution can be 5.0, 5.2, 5.5, 5.8, 6.1, 6.4, 6.7, or 7.0.

[0040] In some implementations, ultrasound-assisted interface separation includes the following parameters: temperature of 40–60°C, ultrasound power of 100–150W, and processing time of 5–10 min.

[0041] By limiting the temperature to 40–60℃, the ultrasonic power to 100–150W, and the processing time to 5–10 min, the separation liquid can be kept in a low-viscosity state to promote molecular diffusion and mass transfer efficiency. Simultaneously, sufficient cavitation bubbles and microjets are generated to drive the mechanical exfoliation of the interfacial adhesive layer and the continuous replenishment of fresh separation liquid, ensuring a sufficient degree of dissociation. For example, the processing temperature for ultrasonic-assisted interfacial separation can be 40℃, 42℃, 45℃, 48℃, 51℃, 54℃, 57℃, 60℃, etc. The ultrasonic power for ultrasonic-assisted interfacial separation can be 100W, 107W, 114W, 121W, 128W, 135W, 142W, 150W, etc. The processing time for ultrasonic-assisted interfacial separation can be 5 min, 5.7 min, 6.4 min, 7.1 min, 7.8 min, 8.5 min, 9.2 min, 10 min, etc.

[0042] In some embodiments, the mass solid-liquid ratio of the pretreated material to the separated liquid is 1:(2 to 2.5).

[0043] Limiting the mass solid-liquid ratio of the pretreatment material to the separation liquid to 1:(2-2.5) ensures that the material has sufficient fluidity in the reactor to undergo uniform ultrasonic treatment, while providing a sufficient total volume of separation liquid to maintain the concentration gradient required for interfacial penetration. For example, the mass solid-liquid ratio of the pretreatment material to the separation liquid can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, etc.

[0044] In some implementations, the magnetic rollers for eddy current sorting operate at a frequency of 200–500 Hz; The voltage for triboelectric electrostatic separation is 50–60 kV.

[0045] The eddy current separating magnetic roller is limited to a frequency of 200–500 Hz to generate an alternating magnetic field of suitable intensity, producing sufficient repulsive force on the aluminum fragments to effectively separate aluminum from the plastic. The triboelectric separation voltage is limited to 50–60 kV to provide sufficient high-voltage electric field strength, ensuring that the charge difference between aluminum and plastic fragments is fully reflected. For example, the operating frequency of the eddy current separating magnetic roller can be 200 Hz, 242 Hz, 285 Hz, 328 Hz, 371 Hz, 414 Hz, 457 Hz, 500 Hz, etc. The triboelectric separation voltage can be 50 kV, 51 kV, 52 kV, 54 kV, 55 kV, 57 kV, 58 kV, 60 kV, etc.

[0046] In some embodiments, the distillation temperature of vacuum distillation is 70–90°C, and the vacuum degree is -0.07 to -0.09 MPa.

[0047] By limiting the vacuum distillation temperature to 70–90°C and the vacuum degree to -0.07–-0.09 MPa, ethylene glycol and water can be vaporized and distilled off at relatively low temperatures. For example, the vacuum distillation temperature can be 70°C, 72°C, 75°C, 78°C, 81°C, 84°C, 87°C, 90°C, etc. The vacuum degree can be -0.07 MPa, -0.0729 MPa, -0.0757 MPa, -0.0786 MPa, -0.0814 MPa, -0.0843 MPa, -0.0871 MPa, -0.09 MPa, etc.

[0048] In some embodiments, the waste aluminum-plastic composite packaging materials include at least one of the following: pharmaceutical aluminum-plastic blister packs, food aluminum-plastic packaging films, paper aluminum-plastic Tetra Pak cartons, or aluminum-PET composite packaging.

[0049] The method provided in this application has good separation universality for both adhesive-containing and adhesive-free hot-pressed aluminum-plastic composite materials. The fundamental reason is that the separation mechanism does not rely on a single targeted separation of a specific interfacial bonding force, but rather achieves a broad-spectrum weakening of interfacial bonding forces with different chemical properties through the synergistic cooperation of chemical penetration and physical external field.

[0050] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0051] Example 1: Separation and Recycling of Pharmaceutical Aluminum-Plastic Blister Sheets S11. Raw material pretreatment: The waste pharmaceutical aluminum-plastic blister packaging material is unpacked and shredded, washed, filtered and dried, then crushed into 10mm-20mm particles, and ground to below 5mm to obtain pretreated material.

[0052] S21. Preparation of separation solution: Mix choline chloride and ethylene glycol at a molar ratio of 1:1.5, then add 6 wt% glycolic acid of the total mass of the separation solution, and stir at 50°C until well mixed to obtain a separation solution with a pH of 6.0. S31. Ultrasonic-assisted interface separation: The pretreated material and the separation liquid are mixed at a mass solid-liquid ratio of 1:2 and placed in a sealed ultrasonic reactor. The mixture is kept at a constant temperature of 50℃ and an ultrasonic power of 120W for 8 minutes to obtain the dissociated mixture.

[0053] S41. Multi-stage physical separation: After drying the dissociated mixture, it is sequentially separated by eddy current separation and triboelectric separation. The magnetic roller of the eddy current separation operates at a frequency of 300Hz, and the voltage of the triboelectric separation is 60kV, separating aluminum and plastic particles.

[0054] S51 Solvent closed-loop recovery: First, the solvent is filtered to remove adhesive impurities, and then ethylene glycol is recovered by vacuum distillation at a temperature of 90℃ and a vacuum degree of -0.09MPa. After condensation and collection, and reproducible proportioning, a regenerated deep eutectic solvent that can be recycled is obtained.

[0055] Example 2: Recycling of Aluminum-Plastic Packaging Film for Food S12. Raw material pretreatment: The waste food aluminum-plastic packaging film is unpacked and shredded, washed and dried, then crushed into 10-20mm particles, and ground to less than 5mm to obtain pretreated material.

[0056] S22. Preparation of separation solution: Mix choline chloride and ethylene glycol at a molar ratio of 1:2, then add 5 wt% glycolic acid of the total mass of the separation solution, and stir at 50°C until well mixed to obtain a separation solution with a pH of 5.5.

[0057] S32. Ultrasonic-assisted interface separation: The pretreated material and the separation liquid are mixed at a mass solid-liquid ratio of 1:2.2 and placed in a sealed ultrasonic reactor. The mixture is kept at a constant temperature of 45°C and an ultrasonic power of 100W for 10 minutes to obtain a dissociated mixture.

[0058] S42. Multi-stage physical separation: After drying the dissociated mixture, it is sequentially subjected to eddy current separation and triboelectric separation, wherein the magnetic roller of the eddy current separation operates at a frequency of 300Hz and the voltage of the triboelectric separation is 60kV, thereby separating aluminum and plastic particles.

[0059] S52. Solvent Closed-Loop Recovery: First, the solvent is filtered to remove adhesive impurities. Then, ethylene glycol is recovered by vacuum distillation at 80℃ and a vacuum of -0.07MPa. After condensation, collection, and reproducible proportioning, a recyclable deep eutectic solvent is obtained. Example 3: Separation and Recycling of Paper-Aluminum-Plastic Tetra Pak Composite Material S13. Raw material pretreatment: The waste paper aluminum-plastic Tetra Pak material is unpacked and shredded, washed with water (hydraulic pulping), filtered, dried, crushed into 10-20mm particles, and ground to below 5mm to obtain pretreated material.

[0060] S23. Preparation of separation solution: Mix choline chloride and ethylene glycol at a molar ratio of 1:2, then add 7 wt% glycolic acid of the total mass of the separation solution, and stir at 55°C until well mixed to obtain a separation solution with a pH of 5.8.

[0061] S33. Ultrasonic-assisted interface separation: The pretreated material and the separation liquid are mixed at a mass solid-liquid ratio of 1:2.5 and placed in a sealed ultrasonic reactor. The mixture is kept at a constant temperature of 55°C and an ultrasonic power of 140W for 9 minutes to obtain a dissociated mixture.

[0062] S43. Multi-stage physical separation: After drying the dissociated mixture, it is sequentially subjected to eddy current separation and triboelectric separation, wherein the magnetic roller of the eddy current separation operates at a frequency of 300Hz and the voltage of the triboelectric separation is 60kV, thereby separating aluminum and plastic particles.

[0063] S53 Solvent closed-loop recovery: First, the solvent is filtered to remove adhesive impurities, and then ethylene glycol is recovered by vacuum distillation at a temperature of 90℃ and a vacuum degree of -0.09MPa. After condensation and collection, and reproducible proportioning, a regenerated deep eutectic solvent that can be recycled is obtained.

[0064] Example 4: Separation and Recycling of High-Adhesion Aluminum-PET Composite Packaging S14. Raw material pretreatment: The waste high-adhesion aluminum-PET composite packaging material is unpacked and shredded, washed, filtered and dried, then crushed into 10-20mm particles, and ground to less than 5mm to obtain pretreated material.

[0065] S24. Preparation of separation solution: Mix choline chloride and ethylene glycol at a molar ratio of 1:1.8, then add 6 wt% glycolic acid of the total mass of the separation solution, and stir at 55°C until well mixed to obtain a separation solution with a pH of 6.2.

[0066] S34. Ultrasonic-assisted interface separation: The pretreated material and the separation liquid are mixed at a mass solid-liquid ratio of 1:2.5 and placed in a sealed ultrasonic reactor. The mixture is kept at a constant temperature of 60°C and an ultrasonic power of 130W for 7 minutes to obtain a dissociated mixture.

[0067] S44. Multi-stage physical separation: After drying the dissociated mixture, it is sequentially subjected to eddy current separation and triboelectric separation, wherein the magnetic roller of the eddy current separation operates at a frequency of 300Hz and the voltage of the triboelectric separation is 60kV, thereby separating aluminum and plastic particles.

[0068] S54 Solvent closed-loop recovery: First, the solvent is filtered to remove adhesive impurities, and then ethylene glycol is recovered by vacuum distillation at a temperature of 90℃ and a vacuum degree of -0.09MPa. After condensation and collection, and reproducible proportioning, a regenerated deep eutectic solvent that can be recycled is obtained.

[0069] Example 5: Adhesive-free hot-pressed composite aluminum-plastic film S15. Raw material pretreatment: The waste non-adhesive layer hot-pressed composite aluminum-plastic film material is unpacked and shredded, washed, filtered and dried, then crushed into 10-20mm particles, and ground to less than 5mm to obtain pretreated material.

[0070] S25. Preparation of separation solution: Mix choline chloride and ethylene glycol at a molar ratio of 1:2, then add 6 wt% glycolic acid of the total mass of the separation solution, and stir at 50°C for 30 min until well mixed to obtain a separation solution with a pH of 6.0.

[0071] S35. Ultrasonic-assisted interface separation: The pretreated material and the separation liquid are mixed at a mass solid-liquid ratio of 1:2.3 and placed in a sealed ultrasonic reactor. The mixture is kept at a constant temperature of 58°C and an ultrasonic power of 130W for 10 minutes to obtain a dissociated mixture.

[0072] S45. Multi-stage physical separation: After drying the dissociated mixture, it is sequentially subjected to eddy current separation and triboelectric separation, wherein the magnetic roller of the eddy current separation operates at a frequency of 400Hz and the voltage of the triboelectric separation is 55kV, thereby separating aluminum and plastic particles.

[0073] S55 Solvent closed-loop recovery: First, the solvent is filtered to remove adhesive impurities, and then ethylene glycol is recovered by vacuum distillation at a temperature of 85℃ and a vacuum degree of -0.09MPa. After condensation and collection, and reproducible proportioning, a regenerated deep eutectic solvent that can be recycled is obtained.

[0074] Comparative Example 1 Using a purely physical sorting process, waste aluminum-plastic composite packaging materials are crushed and ground, and then directly subjected to eddy current separation and triboelectric separation without the use of any chemical separation liquid or ultrasonic-assisted treatment.

[0075] Comparative Example 2 This comparative example is modified from the one disclosed in Example 1 as follows: A sodium hydroxide solution (5% concentration) was used instead of the separation liquid in this application. The same material was treated under the same temperature conditions, and other steps (ultrasonic assistance, solid-liquid ratio, physical sorting, etc.) were kept consistent with those in Example 1.

[0076] Comparative Example 3 This comparative example is modified from the one disclosed in Example 1 as follows: The separation solution consisted only of choline chloride and ethylene glycol (molar ratio 1:2), without the addition of glycolic acid interfacial permeation aid, and the remaining process conditions were consistent with those in Example 1.

[0077] Comparative Example 4 This comparative example is modified from the one disclosed in Example 1 as follows: Conventional mechanical stirring (300 rpm) was used instead of ultrasonic-assisted interface separation, extending the processing time to 60 min. The remaining process conditions remained the same as in Example 1.

[0078] The performance of the methods in Examples 1-5 was compared with that in Comparative Examples 1-4, and the results are shown in Table 1.

[0079] Table 1 Performance of the methods in Examples 1-5 and Comparative Examples 1-4

[0080] As shown in Table 1, the aluminum-plastic composite packaging material separation and recycling methods of Examples 1 to 5 of this application exhibit excellent and stable comprehensive performance, with a dissociation rate of over 95% (95% to 98%), and aluminum foil recycling rate and plastic recycling rate of 96% to 98% and 96% to 98%, respectively.

[0081] Comparative Example 1 uses a purely physical sorting process (without adding separation liquid or ultrasonic assistance), and its dissociation rate is only 75%, while the recycling rates of aluminum foil and plastic are both 82%. This indicates that mechanical sorting after crushing and grinding alone cannot effectively break the interfacial bond of aluminum-plastic composite materials. A large amount of aluminum foil and plastic are still in an adhesive state, resulting in low sorting efficiency.

[0082] Comparative Example 2 used a 5% sodium hydroxide solution instead of the separation liquid of this application. Although the chemical corrosion caused some interface damage and the dissociation rate increased slightly to 82%, the strong alkaline conditions caused severe chemical corrosion to the aluminum foil matrix, resulting in a large amount of aluminum foil fragments being dissolved or deteriorated. The aluminum foil recovery rate plummeted to 68%, which was far lower than the level of the example.

[0083] Comparative Example 3, without the addition of glycolic acid to the separation liquid, had a dissociation rate of only 80%, indicating that without the interfacial penetration aid, the deep eutectic solvent alone had limited ability to penetrate and weaken the intermolecular forces of the colloidal layer and interface, and the interfacial bonding force could not be fully destroyed.

[0084] Comparative Example 4 replaced ultrasonic assistance with conventional mechanical stirring. Even with the processing time extended to 60 min, the dissociation rate was only 81%. This indicates that simply extending the stirring time cannot replace the contribution of the local high-pressure shock wave and micro-jet generated by ultrasonic cavitation effect to the physical stripping of the interface. Furthermore, the shear force of stirring has a limited effect on the dispersion of the dissociated particles, making it difficult to ensure sufficient contact between the separated liquid and the newly formed interface.

[0085] Furthermore, one or more technical solutions in the embodiments of this application have at least the following technical effects or advantages: (1) The present invention uses a compound deep eutectic solvent separation liquid to target and swell the intermediate adhesive layer of aluminum-plastic composites containing adhesives, and to penetrate and destroy the interfacial hydrogen bonds and van der Waals forces of aluminum-plastic composites without adhesives under high temperature hot pressing. The entire process does not corrode or dissolve the aluminum foil substrate, and does not dissolve, embrittle, or degrade the performance of PE, PVC, PET, and PP plastics.

[0086] (2) The raw materials for the separation liquid are all food-grade and daily chemical-grade green raw materials, free from strong acids and alkalis, benzene compounds, heavy metals, and halogens. A small amount of residual liquid can be biodegraded, making it environmentally friendly.

[0087] (3) The process of ultrasonic low temperature assisted separation + vacuum distillation recovery can be recycled more than 12 times, which greatly reduces the consumption of reagents and operating costs, and at the same time reduces energy consumption by more than 30% compared with traditional processes.

[0088] (4) The whole process is compatible with a variety of materials such as pharmaceutical aluminum-plastic blister packs, food aluminum-plastic films, and paper aluminum-plastic Tetra Pak, and can realize continuous industrial production. The process has strong versatility and high degree of automation.

[0089] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for separating and recycling aluminum-plastic composite packaging materials, characterized in that, The method includes: Waste aluminum-plastic composite packaging materials are crushed and ground to obtain pre-treated materials. The deep eutectic solvent and the interfacial permeation aid are mixed to obtain the separation solution; The mixture of the pretreated material and the separation liquid is subjected to ultrasonic-assisted interfacial separation to obtain a dissociated mixture. The dissociated mixture was subjected to eddy current separation and triboelectric separation in sequence to separate aluminum material and plastic particles. The separated liquid after use is recovered by filtration and vacuum distillation, and then compounded to obtain a recyclable deep eutectic solvent. The deep eutectic solvent is composed of choline chloride and ethylene glycol, and the interfacial penetration aid is glycolic acid.

2. The method according to claim 1, characterized in that, The crushing process involves crushing the waste aluminum-plastic composite packaging material into particles of 10mm to 20mm. The grinding process involves grinding to a depth of less than 5 mm.

3. The method according to claim 1, characterized in that, The molar ratio of choline chloride to ethylene glycol is 1:(1.5 to 2.5).

4. The method according to claim 1, characterized in that, The mass of the glycolic acid is 5% to 8% of the total mass of the separated liquid.

5. The method according to claim 1, characterized in that, The pH value of the separation solution is 5.0 to 7.

0.

6. The method according to claim 1, characterized in that, The ultrasound-assisted interface separation includes the following parameters: temperature of 40℃~60℃, ultrasound power of 100W~150W, and processing time of 5min~10min.

7. The method according to claim 1, characterized in that, The mass solid-liquid ratio of the pretreated material to the separated liquid is 1:(2-2.5).

8. The method according to claim 1, characterized in that, The magnetic roller for eddy current separation operates at a frequency of 200Hz to 500Hz. The voltage for the triboelectric electrostatic separation is 50kV to 60kV.

9. The method according to claim 1, characterized in that, The distillation temperature of the vacuum distillation is 70℃~90℃, and the vacuum degree is -0.07MPa~-0.09MPa.

10. The method according to claim 1, characterized in that, The waste aluminum-plastic composite packaging materials include at least one of the following: pharmaceutical aluminum-plastic blister packs, food aluminum-plastic packaging films, paper aluminum-plastic Tetra Pak cartons, or aluminum-PET composite packaging.

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