Mask recycling system and method

Abstract

The present application relates to solid waste recycling technical field, disclose a kind of mask recycling system and method.The mask recycling system includes: the unit for pulverization, for the mask is pulverized and is selected, obtain the mask powder containing iron, aluminum, polar organic matter and nonpolar organic matter;Iron powder separation unit is used for removing iron in the mask powder, obtain the iron powder and the deiron mask powder;Salt and alkali pool unit is used for removing aluminum in the deiron powder, obtain the de-aluminum mask powder;Nonpolar substance recovery unit is used for separating polar organic matter in the de-aluminum powder, obtain the nonpolar organic matter powder containing polyethylene and polypropylene;Dry flotation unit is used for separating polyethylene in nonpolar organic matter powder, obtain polypropylene.The system and method sequentially remove iron, aluminum, polar organic matter and polyethylene in the mask powder according to specific order, realize the thorough separation between each material, so that different materials are recycled respectively.

Description

Technical Field

[0001] This invention relates to the field of solid waste recycling technology, specifically to a mask recycling system and method. Background Technology

[0002] The main chemical components of medical surgical masks are polypropylene (over 90%) and various additives (such as plasticizers, antioxidants, UV absorbers, surfactants, intermediates, etc., accounting for less than 10%). Their structure generally consists of a facepiece, a nose bridge strip, and ear loops. The facepiece includes an outer layer, a middle layer, and an inner layer. The outer layer is usually spunbond nonwoven fabric, mainly composed of polypropylene, which blocks larger particles such as droplets and dust, providing initial filtration. The middle layer is meltblown nonwoven fabric, also mainly composed of polypropylene, but with finer fibers, offering excellent filtration performance and effectively blocking tiny particles such as bacteria and viruses. The inner layer is generally a soft, skin-friendly nonwoven fabric, mostly made of polyester or polypropylene, primarily used to absorb exhaled moisture for wearer comfort. The nose bridge strip is usually made of plastic or metal (aluminum), with common plastic nose bridge strips often also made of polypropylene. Metal nose bridge strips are generally made of galvanized iron or aluminum wire, usually wrapped with a layer of plastic or rubber. Ear loops are made of elastic materials, such as spandex, polyester fiber, and polyethylene. Some ear loops may have small amounts of additives, such as anti-aging agents and softeners, added to improve the performance and user experience.

[0003] The research and development of mask recycling has multifaceted value, including environmental protection, resource recycling, technological innovation, economic benefits, and social responsibility. Therefore, the recycling of discarded masks not only helps reduce environmental pollution but also enables the production of high-performance, high-value-added polymer-based composite materials, achieving resource recycling and yielding significant ecological and economic benefits.

[0004] The shortcomings of traditional mask recycling processes are as follows: 1. Incomplete separation: Metallic impurities such as iron powder are not thoroughly removed, resulting in low purity of recycled materials and affecting the quality of subsequent reprocessing and applications. 2. Poor impurity removal: Simple water washing or physical screening is usually used for impurity removal, which has limited effect on removing organic impurities in materials such as PP (polypropylene). This leads to a decline in the performance of recycled PP, limiting its use to applications with lower quality requirements and restricting its reuse pathways. 3. Low flotation efficiency: The lack of a suitable flotation process results in poor separation when flotating plastics such as PE (polyethylene). The high impurity content in recycled PE affects its reuse value and may lead to resource waste. 4. Narrow application scope: Traditional processes have a limited range of applications for recycled materials, failing to fully explore the characteristics of different materials for diversified reuse. This results in some recycled materials being difficult to utilize effectively due to quality or performance issues, reducing the overall efficiency of mask recycling. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of incomplete separation of different materials, poor impurity removal, low purity of recycled polypropylene, and relatively simple recycled materials in the traditional mask recycling process. This invention provides a mask recycling system and method that removes iron, aluminum, polar organic matter, and polyethylene from mask powder in a specific order, achieving thorough separation of the materials and allowing different materials to be recycled separately, while obtaining polypropylene with high purity.

[0006] To achieve the above objectives, the present invention provides a mask recycling system, which includes:

[0007] The crushing unit is used to crush and screen the masks to obtain mask powder containing iron, aluminum, polar organic matter and non-polar organic matter;

[0008] An iron powder separation unit is used to remove iron from the mask powder to obtain iron-free mask powder and iron powder;

[0009] The salt-alkali pool unit is used to remove aluminum from the de-iron powder to obtain de-aluminized mask powder;

[0010] A non-polar substance recovery unit is used to separate the polar organic matter from the dealuminated powder to obtain a non-polar organic powder containing polyethylene and polypropylene.

[0011] The drying flotation unit is used to separate polyethylene from non-polar organic powder to obtain polypropylene.

[0012] Preferably, the pulverizing unit includes a first blower, a pulverizing device, a second blower, and a collecting device arranged sequentially from top to bottom. The pulverizing device includes a shell and an inner cavity. A cross-cutting pulverizer and a shearing pulverizer are arranged sequentially from top to bottom in the inner cavity. The top of the pulverizing device has an air inlet. The second blower is located on one side of the bottom of the pulverizing device. The other side of the bottom of the pulverizing device has an air outlet opposite to the second blower.

[0013] The mask enters the crushing device through the air inlet under the force of the first blower. After being crushed by the cross-cutting crusher and the shearing crusher in sequence, the crushed mask material with a particle size of 3-5mm is obtained. Under the action of the cross-wind force applied by the second blower, the crushed mask material is screened to obtain small mask powder with a particle size of ≤0.5mm. The small mask powder enters the iron powder separation unit through the air outlet.

[0014] Preferably, the collection device is used to collect large-particle mask powder with a particle size > 0.5 mm that has been screened out under the lateral wind force applied by the second blower.

[0015] Preferably, the iron powder separation unit includes a conveyor belt and an electromagnet disposed on the upper part of the conveyor belt;

[0016] The mask powder from the crushing unit arrives on the conveyor belt through the blower outlet, and the iron in the mask powder is attracted by the electromagnet to obtain iron powder and iron-free mask powder.

[0017] Preferably, the salt-alkali tank unit includes a salt-alkali tank, which has a powder inlet, a first liquid inlet, a first liquid outlet and a powder outlet. A push rod is provided at the powder inlet, and the first liquid inlet is used to add alkali solution to the salt-alkali tank.

[0018] Iron-free mask powder from the iron powder separation unit enters the salt-alkali tank through the powder inlet. The aluminum in the iron-free mask powder reacts with the alkali solution in the salt-alkali tank, and the resulting mixed solution is discharged from the first drain outlet. Iron-free mask powder that cannot react floats on the liquid surface and is pushed to the powder outlet by the push rod to be discharged, thus obtaining aluminum-free mask powder.

[0019] Preferably, the salt-alkali tank is a multi-chamber salt-alkali tank, with a powder discharge port between two adjacent salt-alkali tanks. The iron removal mask powder floating on the liquid surface enters the next salt-alkali tank from the upper salt-alkali tank through the powder discharge port under the action of the push rod, and is finally discharged from the powder outlet.

[0020] Preferably, the non-polar substance recovery unit includes a dissolving tank, a pressure reducing device, and a filtration device. The dissolving tank is provided with a second liquid inlet and a second liquid outlet. The second liquid inlet is used to add a polar solvent to the dissolving tank.

[0021] The aluminum-free mask powder from the saline-alkali pool unit is discharged from the powder outlet and enters the dissolution pool. The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolution pool, while the non-polar organic matter is suspended in the solution. The resulting mixture is discharged from the second drain outlet and enters the filtration device. It is filtered under the action of the pressure reducing device, and the resulting solid product is non-polar organic powder.

[0022] Preferably, the drying flotation unit includes a heating device and a flotation tank. The flotation tank includes an inlet, a third liquid inlet, and a third liquid outlet. The third liquid inlet is used to add a wetting agent aqueous solution to the flotation tank.

[0023] Non-polar organic powder from the non-polar substance recovery unit enters the heating device through a conveying pipe. The heating process causes the solution on the surface of the non-polar organic powder to evaporate. The heated non-polar organic powder then enters the flotation tank through the inlet. Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats. The mixture of polyethylene and wetting agent is discharged from the third outlet to obtain polypropylene.

[0024] Preferably, the flotation tank is equipped with a fan to accelerate the flotation of polypropylene.

[0025] A second aspect of the present invention provides a method for recycling face masks, which is implemented using the face mask recycling system described above. The method includes:

[0026] The mask is crushed and screened to obtain mask powder, which contains iron, aluminum, polar organic matter and non-polar organic matter;

[0027] Iron is separated from the mask powder to obtain iron-free mask powder and iron powder;

[0028] The aluminum in the de-ferrous powder is separated and removed to obtain de-aluminized mask powder;

[0029] The polar organic matter in the aluminum-free mask powder is removed to obtain a non-polar organic powder, which contains polyethylene and polypropylene.

[0030] Polyethylene was separated from the non-polar organic powder to obtain polypropylene.

[0031] Preferably, the process of separating and removing aluminum from the iron-removing powder to obtain aluminum-removed mask powder includes: reacting the aluminum in the iron-removing mask powder with an alkaline solution; the unreacted iron-removing mask powder floats on the liquid surface and is then discharged to obtain aluminum-removed mask powder.

[0032] Preferably, the alkaline solution is a sodium hydroxide solution and / or a potassium hydroxide solution.

[0033] Preferably, the process of removing polar organic matter from the aluminum-free mask powder to obtain non-polar organic matter powder includes: mixing the aluminum-free mask powder with a polar solvent, dissolving the polar organic matter in the aluminum-free mask powder in the polar solvent, and suspending the non-polar organic matter in the solution, and then filtering under reduced pressure to obtain a solid product, which is non-polar organic matter powder.

[0034] Preferably, the polar solvent is ethylene glycol and / or dimethyl sulfoxide.

[0035] Preferably, the process of separating polyethylene from non-polar organic powder to obtain polypropylene includes: heating the non-polar organic powder to volatilize the surface of the non-polar organic powder, then mixing the heated non-polar organic powder with a wetting agent, whereby polyethylene sinks under the action of the wetting agent aqueous solution and polypropylene floats, and polypropylene is obtained after separation.

[0036] Preferably, the wetting agent aqueous solution is an aqueous solution of calcium lignosulfonate and / or an aqueous solution of sodium dodecyl sulfate.

[0037] Compared with the prior art, the present invention has at least the following technical effects:

[0038] (1) The mask recycling system and method provided by the present invention removes iron, aluminum, polar organic matter and polyethylene from the mask powder in a specific order, thereby achieving complete separation between the materials and recycling the different materials separately, while obtaining iron powder and polypropylene with high purity.

[0039] In a preferred embodiment, the present invention utilizes magnetic separation technology to effectively separate metal components such as iron powder from mask materials, thereby improving the purity of the recycled materials and enabling different materials to be recycled more effectively, thus achieving refined separation.

[0040] In preferred cases, adding polar organic solvents to remove polar organic impurities from mask powder can remove organic impurities more thoroughly than traditional physical screening or simple washing, thereby improving the quality of recycled polypropylene and expanding its re-application scope.

[0041] In a preferred embodiment, a wetting agent aqueous solution, particularly a calcium lignosulfonate aqueous solution, is used in the flotation unit for flotation. Polypropylene floats because it is less dense than water and is hydrophilic, while polyethylene sinks because the calcium lignosulfonate is adsorbed on its surface, making the flotation process more efficient and facilitating the separation of polypropylene and polyethylene, thus ensuring the quality of the recovered polypropylene and polyethylene.

[0042] (2) This invention recovers polypropylene and polyethylene through a multi-step process, which can be used in construction sites, plastic manufacturing, textile products, etc., to create economic value. Furthermore, the recovered polypropylene and polyethylene can be reused in multiple ways. Specifically, the recovered polypropylene can be used for melt spinning and the recovered polyethylene can be used for melt regeneration and reconstruction, giving full play to the characteristics of different materials, realizing efficient recycling of resources, and improving the economic value and environmental benefits of the entire recycling process.

[0043] (3) The present invention also separates iron and aluminum, providing them as raw materials for some factories and improving the resource recovery rate.

[0044] (4) The system and method described in this invention reduce labor costs and enable large-scale mask recycling, while reducing the generation of pollutants and protecting the environment. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the mask recycling system described in this invention.

[0046] Explanation of reference numerals in the attached figures

[0047] 1 First blower; 2 Cross-cutting pulverizer; 3 Shear pulverizer; 4 Blower outlet; 5 Second blower; 6 Collection device; 7 Electromagnet; 8 Conveyor belt; 9 Salt and alkali tank; 10 First liquid inlet; 11 Powder inlet; 12 Push rod; 13 First liquid outlet; 14 Powder outlet; 15 Powder outlet; 16 Dissolving tank; 17 Second liquid inlet; 18 Second liquid outlet; 19 Pressure reducing device; 20 Filtration device; 21 Heating device; 22 Flotation tank; 23 Input port; 24 Third liquid inlet; 25 Fan; 26 Third liquid outlet; 27 Conveying pipeline; 28 Outer shell; 29 Inner cavity; 30 Blower inlet; 40 Pulverizing unit; 50 Iron powder separation unit; 60 Salt and alkali tank unit; 70 Non-polar substance recovery unit; 80 Drying flotation unit. Detailed Implementation

[0048] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0050] like Figure 1 As shown, the mask recycling system provided by the present invention includes a crushing unit 40, an iron powder separation unit 50, a saline-alkali pond unit 60, a non-polar substance recovery unit 70, and a drying flotation unit 80. The crushing unit 40 is used to crush and screen the mask to obtain mask powder containing iron, aluminum, polar organic matter, and non-polar organic matter. The iron powder separation unit 50 is used to remove iron from the mask powder to obtain iron-free mask powder and iron powder. The saline-alkali pond unit 60 is used to remove aluminum from the iron-free powder to obtain aluminum-free mask powder. The non-polar substance recovery unit 70 is used to separate polar organic matter from the aluminum-free powder to obtain non-polar organic powder containing polyethylene and polypropylene. The drying flotation unit 80 is used to separate polyethylene from the non-polar organic powder to obtain polypropylene.

[0051] In the mask recycling system described in this invention, the mask is first pulverized in the pulverizing unit 40 to obtain mask powder. The smaller particle size of the powder material is beneficial for improving the recovery rate and separation efficiency of subsequent materials. In the iron powder separation unit 50, the iron in the mask powder is separated from other components, yielding iron powder and de-ironized mask powder respectively. Separating the iron first avoids iron powder loss and improves the iron recovery rate. Furthermore, after the iron is separated, other materials in the de-ironized mask powder are easier to recover, resulting in higher purity recovered materials. In the saline-alkali pond unit 60, the de-ironized mask powder... Aluminum is removed from the aluminum in the mask powder, resulting in a dealuminized mask powder containing mainly polar and non-polar organic matter. In this step, aluminum reacts with the alkaline solution in the salt-alkali tank to form aluminum salts. The unreacted portion mainly contains polar and non-polar organic matter, thus achieving the separation of aluminum and organic matter. In the non-polar substance recovery unit 70, the polar and non-polar organic matter in the dealuminized mask powder are separated. After removing the polar organic matter, a non-polar organic powder containing polyethylene and polypropylene is obtained. In the drying flotation unit 80, polyethylene and polypropylene are separated to obtain polypropylene with higher purity.

[0052] In this invention, the masks used for recycling can be common types of masks in the art, such as ordinary masks, ordinary medical masks, and medical surgical masks, preferably medical surgical masks. The polar organic matter generally originates from additives such as anti-aging agents and softeners, while the non-polar organic matter includes polypropylene and polyethylene.

[0053] like Figure 1 As shown, the crushing unit 40 includes a first blower 1, a crushing device, a second blower 5, and a collecting device 6 arranged sequentially from top to bottom. The crushing device includes a shell 28 and an inner cavity 29. A cross-cutting crusher 2 and a shearing crusher 3 are arranged sequentially from top to bottom in the inner cavity. The top of the crushing device has an air inlet 30. The second blower 5 is located on one side of the bottom of the crushing device. An air outlet 4 opposite to the second blower 5 is provided on the other side of the bottom of the crushing device.

[0054] The working process of the crushing unit 40 is as follows: the mask enters the crushing device from the blower inlet 30 under the action of the first blower 1, and is crushed by the cross-cutting crusher 2 and the shear crusher 3 in sequence to obtain crushed mask material with a particle size of 3-5mm. The crushed mask material is screened out into small mask powder with a particle size of ≤0.5mm under the action of the cross-wind force applied by the second blower 5. The small mask powder enters the iron powder separation unit 50 through the blower outlet 4.

[0055] In the crushing unit 40, the first blower 1 is installed at the air inlet 30. The function of the first blower 1 is to accelerate the entry efficiency of the mask into the air inlet 30, prevent blockage, and improve the crushing efficiency of the mask.

[0056] In this invention, the collecting device 6 is used to collect large-particle mask powder with a particle size >0.5mm that has been screened out by the lateral airflow applied by the second blower 5. During the crushing process, the mask enters the cross-cutting crusher 2 under gravity for initial crushing, and then enters the shearing crusher 3 for thorough crushing. After two crushing processes, the crushed mask material falls to the bottom of the crushing device under gravity. The large-particle mask powder that was not completely crushed after being crushed by the cross-cutting crusher 2 and the shearing crusher 3 cannot enter the blower outlet 4 under the lateral airflow of the second blower 5, and is finally collected in the collecting device 6 for re-crushing.

[0057] like Figure 1 As shown, the iron powder separation unit 50 includes a conveyor belt 8 and an electromagnet 7 disposed on the upper part of the conveyor belt 8. In one embodiment, the conveyor belt 8 can be located directly below the air outlet 4. Small particles of mask powder from the crushing unit 40 fall onto the conveyor belt 8 through the air outlet 4. During the conveying process of the conveyor belt 8, the iron in the mask powder is attracted by the electromagnet 7 on the upper part of the conveyor belt 8. The iron powder is separated under the attraction of magnetic force and thus adsorbed onto the electromagnet 7. What remains on the conveyor belt 8 is the mask powder after iron removal. Finally, separated iron powder and iron-removed mask powder are obtained, and the purity of the iron powder is relatively high. In this invention, using a conveyor belt 8 to transport small particles of mask powder can make them evenly separated, improve the absorption efficiency of iron powder, and improve the removal rate and recovery rate of iron powder. The iron powder collected on the electromagnet 7 can be used to re-process iron.

[0058] In this invention, such as Figure 1As shown, the salt and alkali tank unit 60 includes a salt and alkali tank 9, which has a powder inlet 11, a first liquid inlet 10, a first liquid outlet 13, and a powder outlet 15. A push rod 12 is provided at the powder inlet 11. The first liquid inlet 10 is used to add alkali solution to the salt and alkali tank 9. Its setting position is not limited, as long as it can add alkali solution to the salt and alkali tank 9. For example, it can be set above the powder inlet 11. In one embodiment, the first drain port 13 is located at the bottom of the saline-alkali tank 9. Iron-removed mask powder from the conveyor belt 8 in the iron powder separation unit 50 enters the saline-alkali tank 9 through the powder inlet 11. The aluminum in the iron-removed mask powder reacts with the alkaline solution in the saline-alkali tank 9 to generate aluminum salts. The mixed solution containing alkaline solution and aluminum salts obtained in the saline-alkali tank 9 is discharged from the first drain port 13. Iron-removed mask powder containing polar and non-polar organic matter cannot react and floats on the surface, being pushed to the powder outlet 15 by the push rod 12. The powder discharged from the powder outlet 15 is aluminum-removed mask powder containing polar and non-polar organic matter. The aluminum-containing solution collected by the first drain port 13 can be used as industrial aluminum liquid.

[0059] In some embodiments, the alkaline solution can be a sodium hydroxide solution and / or a potassium hydroxide solution. Further, the alkaline solution can dissolve esters in the mask; if the mask contains esters, the solution discharged from the first drain port 13 will be a mixed solution containing alkaline solution, aluminum salts, and esters.

[0060] To improve the aluminum removal rate of the iron-free mask powder, the saline-alkali tank can be a multi-chamber saline-alkali tank. A powder discharge port 14 is provided between adjacent saline-alkali tanks. The iron-free mask powder floating on the liquid surface enters the next saline-alkali tank from the upper chamber through the powder discharge port 14 under the action of the push rod 12, and is finally discharged from the powder outlet 15. In one embodiment, the saline-alkali tank 9 is a three-chamber saline-alkali tank. The first chamber is provided with a powder inlet 11, and powder discharge ports 14 are provided between the first and second chambers, and between the second and third chambers. The third chamber is provided with a powder outlet 15. Each of the first, second, and third chambers is provided with a first liquid inlet 10, a push rod 12, and a first liquid outlet 13.

[0061] Iron-removed mask powder from the conveyor belt 8 in the iron powder separation unit 50 enters the first-chamber salt-alkali tank through the powder inlet 11. The aluminum in the iron-removed mask powder reacts with the alkaline solution in the first-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain outlet 13 in the first-chamber salt-alkali tank. Iron-removed mask powder containing polar organic matter and non-polar organic matter cannot react and floats on the surface. It is pushed to the discharge outlet 14 between the first and second-chamber salt-alkali tanks by the push rod 12 in the first-chamber salt-alkali tank and enters the second-chamber salt-alkali tank. The residual aluminum in the iron-removed mask powder containing polar organic matter and non-polar organic matter reacts with the alkaline solution in the second-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain outlet 13 in the second-chamber salt-alkali tank. The iron-removed mask powder containing both organic and non-polar organic matter cannot react and will float on the surface of the liquid. It will be driven by the push rod 12 in the two-chamber salt-alkali tank to the discharge port 14 between the two-chamber and three-chamber salt-alkali tanks and enter the third-chamber salt-alkali tank. The aluminum residue in the iron-removed mask powder containing both polar and non-polar organic matter reacts with the alkali solution in the three-chamber salt-alkali tank to generate aluminum salt. The mixed solution containing alkali solution and aluminum salt is discharged from the first discharge port 13 in the three-chamber salt-alkali tank. The iron-removed mask powder containing both polar and non-polar organic matter cannot react and will float on the surface of the liquid. It will be driven by the push rod 12 in the three-chamber salt-alkali tank to the powder outlet 15 in the three-chamber salt-alkali tank. At this time, the aluminum-removed mask powder (with higher purity of polar and non-polar organic matter) is discharged from the powder outlet 15 and enters the non-polar substance recovery unit 70.

[0062] In one embodiment, the non-polar substance recovery unit 70 includes a dissolving tank 16, a pressure reducing device 19, and a filtration device 20. The dissolving tank 16 is provided with a second liquid inlet 17 and a second liquid outlet 18. The second liquid inlet 17 is used to add a polar solvent to the dissolving tank 16. The function of the dissolving tank 16 is to separate the polar organic matter and non-polar organic matter in the aluminum-removing mask powder into layers, facilitating subsequent filtration and separation. In the dissolving tank 16, polar organic matter can dissolve in the polar solvent, while non-polar organic matter cannot dissolve in the polar solvent and remains suspended in the solution, thus achieving layering. Specifically, the aluminum-free mask powder from the saline-alkali tank unit 6 is discharged from the powder outlet 15 and enters the dissolution tank 16. The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolution tank 16, while the non-polar organic matter remains suspended in the solution. The resulting stratified mixture is discharged from the second drain outlet 18 and enters the filtration device 20. Under the action of the pressure reducing device 19, filtration is performed to obtain a mixed liquid containing polar organic matter and a solid product. The obtained solid product is a non-polar organic powder. The pressure reducing device 19 can reduce the pressure and accelerate the filtration speed.

[0063] In some embodiments, the polar solvent may be ethylene glycol and / or dimethyl sulfoxide.

[0064] like Figure 1 As shown, the drying flotation unit 80 includes a heating device 21 and a flotation tank 22. The flotation tank 22 includes an inlet 23, a third liquid inlet 24, and a third liquid outlet 26. The third liquid inlet 24 is used to add a wetting agent aqueous solution to the flotation tank 22. Non-polar organic powder from the non-polar substance recovery unit 70 enters the heating device 21 through a conveying pipe 27. The heating treatment causes the solution on the surface of the non-polar organic powder (including the alkaline solution, polar solvent, etc. added in the aforementioned steps) to evaporate, removing impurities on the one hand and avoiding affecting the subsequent reaction to change the hydrophilicity in the flotation tank 22 on the other hand. The heated non-polar organic powder enters the flotation tank 22 through the inlet 23. Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats due to its hydrophobicity and lower density than water. The mixture of polyethylene and the wetting agent aqueous solution is discharged from the third liquid outlet 26. The polypropylene with higher purity is collected in the flotation tank 22, thus obtaining polypropylene. The polyethylene solution discharged from the third drain port 26 can be dried and then melted and reused to manufacture plastic products; the collected polypropylene can be dried, melt-spun into fabric, or added to building materials to enhance toughness.

[0065] In this invention, the wetting agent aqueous solution can be an aqueous solution of calcium lignosulfonate and / or an aqueous solution of sodium dodecyl sulfate. To improve flotation efficiency and enable more efficient separation of polypropylene and polyethylene, the wetting agent is an aqueous solution of calcium lignosulfonate. In some embodiments, the mass fraction of the wetting agent aqueous solution is 0.2-0.5%.

[0066] In one embodiment, a fan 25 may be provided in the flotation tank 22, preferably in the lower part of the flotation tank 22, to accelerate the flotation of polypropylene.

[0067] Furthermore, in addition to iron, aluminum, polar organic matter, polypropylene, and polyethylene, the remaining components in the mask are either dissolved or precipitated in the alkaline solution in the saline-alkali pool 9 due to the alkaline conditions, and discharged from the first drain outlet 13; another part is further separated and precipitated by the polar organic matter in the dissolution pool 16, and the last part is discharged from the third drain outlet 26 as the polyethylene sinks in the flotation tank 22.

[0068] In one specific implementation, such as Figure 1As shown, the mask recycling system provided by this invention includes a crushing unit 40, an iron powder separation unit 50, a saline-alkali pond unit 60, a non-polar substance recovery unit 70, and a drying flotation unit 80. The crushing unit 40 includes a first blower 1, a crushing device, a second blower 5, and a collecting device 6 arranged sequentially from top to bottom. The crushing device includes a shell 28 and an inner cavity 29. A transverse crusher 2 and a shear crusher 3 are arranged sequentially from top to bottom in the inner cavity. The top of the crushing device has an air inlet 30. The second blower 5 is located on one side of the bottom of the crushing device, and the other side of the bottom of the crushing device has an air outlet 4 opposite to the second blower 5. The mask is placed in the first blower 1... Under the action of wind, the material enters the pulverizing device through the blower inlet 30 and is pulverized sequentially by the cross-cutting pulverizer 2 and the shearing pulverizer 3 to obtain pulverized mask material with a particle size of 3-5mm. The pulverized mask material is then screened out by the lateral wind force applied by the second blower 5 to obtain small mask powder particles with a particle size ≤0.5mm. These small mask powder particles enter the iron powder separation unit 50 through the blower outlet 4. Large mask powder particles larger than 0.5mm that were not completely pulverized after being pulverized by the cross-cutting pulverizer 2 and the shearing pulverizer 3 are collected in the collection device 6 and pulverized again. The iron powder separation unit 50 includes a conveyor belt 8 and an electromagnet 7 disposed on the upper part of the conveyor belt 8. The conveyor belt 8 can be located directly below the blower outlet 4. Small particles of mask powder from the crushing unit 40 fall onto the conveyor belt 8 through the blower outlet 4. During the conveying process of the conveyor belt 8, the iron in the mask powder is attracted by the electromagnet 7 at the top of the conveyor belt 8. The iron powder is separated under the attraction of the magnetic force and thus adsorbed onto the electromagnet 7. What remains on the conveyor belt 8 is the mask powder after iron removal, finally obtaining separated iron powder and iron-removed mask powder; the salt-alkali tank unit 60 includes a salt-alkali tank 9, which is a three-chamber salt-alkali tank. The first chamber salt-alkali tank is provided with a powder inlet 11, and powder outlets 14 are provided between the first and second chamber salt-alkali tanks and between the second and third chamber salt-alkali tanks. The pool is equipped with a powder outlet 15. The first-chamber salt-alkali pool, the second-chamber salt-alkali pool, and the third-chamber salt-alkali pool are all equipped with a first liquid inlet 10, a push rod 12, and a first liquid outlet 13. After the iron-removed mask powder from the conveyor belt 8 in the iron powder separation unit 50 enters the first-chamber salt-alkali pool through the powder inlet 11, the aluminum in the iron-removed mask powder reacts with the alkali solution in the first-chamber salt-alkali pool to generate aluminum salt. The mixed solution containing alkali solution and aluminum salt is discharged from the first liquid outlet 13 in the first-chamber salt-alkali pool. The iron-removed mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the liquid surface. It will be pushed to the powder outlet 14 between the first-chamber salt-alkali pool and the second-chamber salt-alkali pool by the push rod 12 in the first-chamber salt-alkali pool and enter the second-chamber salt-alkali pool.The residual aluminum in the iron-removed mask powder containing polar and non-polar organic matter reacts with the alkaline solution in the two-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain port 13 in the two-chamber salt-alkali tank. The iron-removed mask powder containing polar and non-polar organic matter does not react and floats on the surface. It is pushed to the discharge port 14 between the two-chamber and three-chamber salt-alkali tanks by the push rod 12 in the two-chamber salt-alkali tank, entering the third-chamber salt-alkali tank. The residual aluminum in the iron-removed mask powder containing polar and non-polar organic matter reacts with the alkaline solution in the three-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain port 13 in the three-chamber salt-alkali tank. The first drain outlet 13 in the pool discharges the iron-removing mask powder containing polar and non-polar organic matter. Since the powder cannot react, it floats on the surface and is pushed to the powder outlet 15 of the three-chamber salt-alkali pool by the push rod 12. The resulting aluminum-removing mask powder (with high purity of polar and non-polar organic matter) is then discharged from the powder outlet 15 and enters the non-polar substance recovery unit 70. The non-polar substance recovery unit 70 includes a dissolving pool 16, a pressure reducing device 19, and a filtration device 20. The dissolving pool 16 is equipped with a second inlet 17 and a second drain 18. The second inlet 17 is used to add a polar solvent from the salt-alkali pool to the dissolving pool 16. The aluminum-free mask powder from Unit 6 is discharged from the powder outlet 15 and enters the dissolution tank 16. The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolution tank 16, while the non-polar organic matter remains suspended in the solution. The resulting stratified mixture is discharged from the second drain outlet 18 and enters the filtration device 20. Filtration is performed under the action of the pressure reducing device 19, yielding a mixture containing polar organic matter and a solid product. The solid product is a non-polar organic powder. The drying flotation unit 80 includes a heating device 21 and a flotation tank 22. The flotation tank 22 includes an inlet 23, a third liquid inlet 24, and a third drain outlet 26. The third inlet 24 is used to add a wetting agent aqueous solution to the flotation tank 22. Non-polar organic powder from the non-polar substance recovery unit 70 enters the heating device 21 through the conveying pipe 27. Heating causes the solution on the surface of the non-polar organic powder (including the alkali solution and polar solvent solutions added in the previous steps) to evaporate. The heated non-polar organic powder then enters the flotation tank 22 through the inlet 23. Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats. The mixture of polyethylene and wetting agent is discharged from the third outlet 26. The flotation tank 22 collects high-purity polypropylene, thus obtaining polypropylene.

[0069] Furthermore, the present invention also provides a method for recycling face masks, which is implemented using the face mask recycling system described above. The method includes:

[0070] (1) The mask is crushed and screened to obtain mask powder, wherein the mask powder contains iron, aluminum, polar organic matter and non-polar organic matter;

[0071] (2) Separate the iron from the mask powder to obtain iron-free mask powder and iron powder;

[0072] (3) Remove aluminum from the iron-free powder to obtain aluminum-free mask powder;

[0073] (4) Remove the polar organic matter from the aluminum-free mask powder to obtain non-polar organic powder, wherein the non-polar organic powder contains polyethylene and polypropylene;

[0074] (5) Polyethylene is separated from the non-polar organic powder to obtain polypropylene.

[0075] In one embodiment, the process of crushing and screening the mask to obtain mask powder in step (1) includes: the mask enters the crushing device from the blower inlet 30 under the action of the wind force of the first blower 1, and is crushed by the cross-cutting crusher 2 and the shearing crusher 3 in sequence to obtain crushed mask material with a particle size of 3-5mm. The crushed mask material is screened out into small particle mask powder with a particle size of ≤0.5mm under the action of the cross-wind force applied by the second blower 5.

[0076] In one embodiment, step (2) of separating iron from the mask powder to obtain iron-free mask powder and iron powder includes: small particles of mask powder fall onto the conveyor belt 8 through the blower outlet 4; during the conveying process of the conveyor belt 8, the iron in the mask powder is attracted by the electromagnet 7 on the upper part of the conveyor belt 8; the iron powder is separated under the attraction of the magnetic force and thus adsorbed on the electromagnet 7; what remains on the conveyor belt 8 is the iron-free mask powder; finally, the separated iron powder and iron-free mask powder are obtained.

[0077] In one embodiment, step (3), which involves separating and removing aluminum from the iron-removing powder to obtain aluminum-removed mask powder, includes: reacting the aluminum in the iron-removing mask powder with an alkaline solution; the unreacted iron-removing mask powder floats on the surface of the liquid and is then discharged, resulting in aluminum-removed mask powder. More specifically, the iron-removing mask powder enters the salt-alkali tank 9 through the powder inlet 11. The aluminum in the iron-removing mask powder reacts with the alkaline solution in the salt-alkali tank 9 to generate aluminum salts. The mixed solution containing alkaline solution and aluminum salts obtained in the salt-alkali tank 9 is then discharged from the first drain outlet 13. The iron-removing mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface of the liquid. It will be pushed to the powder outlet 15 by the push rod 12 and discharged. The aluminum-removed mask powder containing polar organic matter and non-polar organic matter is discharged from the powder outlet 15.

[0078] In some embodiments, the alkaline solution can be a sodium hydroxide solution and / or a potassium hydroxide solution. Further, the alkaline solution can dissolve esters in the mask; if the mask contains esters, the solution discharged from the first drain port 13 will be a mixed solution containing alkaline solution, aluminum salts, and esters.

[0079] In one embodiment, step (4), the process of removing polar organic matter from the aluminum-free mask powder to obtain non-polar organic matter powder, includes: mixing the aluminum-free mask powder with a polar solvent, dissolving the polar organic matter in the polar solvent, and suspending the non-polar organic matter in the solution, and then filtering under reduced pressure to obtain a non-polar organic matter powder as the solid product. More specifically, after the aluminum-free mask powder is discharged from the powder outlet 15, it enters the dissolution tank 16, where the polar organic matter is dissolved in the polar solvent in the dissolution tank 16, and the non-polar organic matter is suspended in the solution. The resulting stratified mixture is discharged from the second drain outlet 18 and enters the filtration device 20, where it is filtered under the action of the reduced pressure device 19 to obtain a mixture containing polar organic matter and a solid product, the solid product being a non-polar organic matter powder.

[0080] In some embodiments, the polar solvent may be ethylene glycol and / or dimethyl sulfoxide.

[0081] In one embodiment, step (5), separating polyethylene from the non-polar organic powder to obtain polypropylene, includes: heating the non-polar organic powder to volatilize its surface, then mixing the heated non-polar organic powder with a wetting agent aqueous solution. The polyethylene sinks under the influence of the wetting agent aqueous solution, while the polypropylene floats, resulting in polypropylene after separation. Specifically, the non-polar organic powder from the non-polar substance recovery unit 70 enters the heating device 21 through the conveying pipe 27. Heating causes the solution on the surface of the non-polar organic powder (including the alkali solution, polar solvent, etc. added in the aforementioned steps) to volatilize. The heated non-polar organic powder enters the flotation tank 22 from the inlet 23. The polyethylene sinks under the influence of the wetting agent aqueous solution, while the polypropylene floats due to its hydrophobicity. The mixture of polyethylene and the wetting agent aqueous solution is discharged from the third outlet 26. The flotation tank 22 collects polypropylene with higher purity, thus obtaining polypropylene.

[0082] In this invention, the wetting agent aqueous solution is an aqueous solution of calcium lignosulfonate and / or an aqueous solution of sodium dodecyl sulfate. To improve flotation efficiency and enable more efficient separation of polypropylene and polyethylene, the wetting agent aqueous solution is an aqueous solution of calcium lignosulfonate. In some embodiments, the mass fraction of the wetting agent aqueous solution is 0.2-0.5%.

[0083] The advantages of the mask recycling system and method provided by this invention are as follows: 1. Refined separation: Magnetic separation technology effectively separates metal components such as iron powder from the mask material, improving the purity of the recycled material and enabling different materials to be reused separately. 2. Organic solvent removal: By adding polar organic solvents to remove polar organic impurities from the mask powder, compared with traditional physical screening or simple washing, organic impurities can be removed more thoroughly, improving the quality of recycled polypropylene and broadening its reuse range. 3. Targeted wetting flotation: In the flotation unit, a wetting agent aqueous solution, especially a calcium lignosulfonate aqueous solution, is used for flotation, making the flotation process more efficient and facilitating the separation of polypropylene and polyethylene, ensuring the quality of the recycled polypropylene and polyethylene. 4. Diverse Recycling: This invention recycles polypropylene and polyethylene through a multi-step process, which can be used in construction sites, plastic manufacturing, textile products, etc., creating economic value. Furthermore, the recycled polypropylene and polyethylene can be reused in multiple ways. Specifically, the recycled polypropylene can be used for melt spinning, and the recycled polyethylene can be used for melt regeneration and reprocessing, giving full play to the characteristics of different materials, realizing efficient recycling of resources, and improving the economic value and environmental benefits of the entire recycling process.

[0084] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products commonly found in the art.

[0085] Example 1

[0086] In this embodiment, the alkaline solution is a sodium hydroxide solution with a concentration of 11 mol / L; the polar solvent is ethylene glycol; and the wetting agent aqueous solution is a calcium lignosulfonate aqueous solution with a mass fraction of 0.3%.

[0087] like Figure 1 As shown, the mask recycling system includes a crushing unit 40, an iron powder separation unit 50, a salt and alkali pond unit 60, a non-polar substance recovery unit 70, and a drying and flotation unit 80.

[0088] The pulverizing unit 40 includes a first blower 1, a pulverizing device, a second blower 5, and a collecting device 6 arranged sequentially from top to bottom. The pulverizing device includes a shell 28 and an inner cavity 29. A cross-cutting pulverizer 2 and a shearing pulverizer 3 are arranged sequentially from top to bottom in the inner cavity. The top of the pulverizing device has an air inlet 30. The second blower 5 is located on one side of the bottom of the pulverizing device, and the other side of the bottom of the pulverizing device has an air outlet 4 opposite to the second blower 5. The mask is exposed to air from the air inlet 30 under the force of the first blower 1. After entering the crushing device, the material is crushed by the cross-cutting crusher 2 and the shearing crusher 3 in sequence to obtain crushed mask material with a particle size of 3-5mm. The crushed mask material is screened out by the lateral wind force applied by the second blower 5 to obtain small mask powder particles with a particle size ≤0.5mm. The small mask powder particles enter the iron powder separation unit 50 through the blower outlet 4. The large mask powder particles >0.5mm that were not completely crushed after being crushed by the cross-cutting crusher 2 and the shearing crusher 3 are collected in the collection device 6 and crushed again.

[0089] The iron powder separation unit 50 includes a conveyor belt 8 and an electromagnet 7 disposed on the upper part of the conveyor belt 8. The conveyor belt 8 can be located directly below the blower outlet 4. Small particles of mask powder from the crushing unit 40 fall onto the conveyor belt 8 through the blower outlet 4. During the conveying process of the conveyor belt 8, the iron in the mask powder is attracted by the electromagnet 7 on the upper part of the conveyor belt 8. The iron powder is separated under the attraction of the magnetic force and thus adsorbed on the electromagnet 7. What remains on the conveyor belt 8 is the mask powder after iron removal. Finally, the separated iron powder and iron-removed mask powder are obtained.

[0090] The saline-alkali tank unit 60 includes a saline-alkali tank 9, which is a three-chamber saline-alkali tank. The first chamber is equipped with a powder inlet 11. Powder outlets 14 are located between the first and second chambers, and between the second and third chambers. The third chamber is equipped with a powder outlet 15. Each of the first, second, and third chambers is equipped with a first liquid inlet 10, a push rod 12, and a first liquid outlet 13. Iron-removing mask powder from the conveyor belt 8 in the iron powder separation unit 50 exits from the first chamber of the saline-alkali tank. After entering the first-chamber salt-alkali tank through the powder inlet 11, the aluminum in the iron-removing mask powder reacts with the alkaline solution in the first-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain outlet 13 in the first-chamber salt-alkali tank. However, the iron-removing mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface. It will be pushed to the powder outlet 14 between the first-chamber and second-chamber salt-alkali tanks by the push rod 12 in the first-chamber salt-alkali tank and enter the second-chamber salt-alkali tank. The residual aluminum in the iron-free mask powder reacts with the alkaline solution in the two-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain port 13 in the two-chamber salt-alkali tank. The iron-free mask powder containing polar and non-polar organic matter does not react and floats on the surface. It is then pushed by the push rod 12 in the two-chamber salt-alkali tank to the powder discharge port 14 between the two-chamber and three-chamber salt-alkali tanks, entering the third-chamber salt-alkali tank. The residual aluminum in the iron-free mask powder containing polar and non-polar organic matter... Aluminum reacts with the alkaline solution in the three-chamber salt-alkali tank to generate aluminum salt. The aluminum-containing solution containing the alkaline solution and aluminum salt is discharged from the first drain port 13 in the three-chamber salt-alkali tank. The iron-removed mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface of the liquid. It will be pushed to the powder outlet 15 of the three-chamber salt-alkali tank by the push rod 12. At this time, the aluminum-removed mask powder (with high purity of polar organic matter and non-polar organic matter) is discharged from the powder outlet 15 and enters the non-polar substance recovery unit 70.

[0091] The non-polar substance recovery unit 70 includes a dissolving tank 16, a pressure reducing device 19, and a filtration device 20. The dissolving tank 16 is provided with a second liquid inlet 17 and a second liquid outlet 18. The second liquid inlet 17 is used to add a polar solvent to the dissolving tank 16. The aluminum-free mask powder from the salt-alkali tank unit 6 is discharged from the powder outlet 15 and enters the dissolving tank 16. The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolving tank 16, while the non-polar organic matter is suspended in the solution. The resulting stratified mixture is discharged from the second liquid outlet 18 and enters the filtration device 20. It is filtered under the action of the pressure reducing device 19 to obtain a mixed liquid containing polar organic matter and a solid product. The obtained solid product is a non-polar organic matter powder.

[0092] The drying flotation unit 80 includes a heating device 21 and a flotation tank 22. The flotation tank 22 includes an inlet 23, a third liquid inlet 24, and a third liquid outlet 26. The third liquid inlet 24 is used to add a wetting agent aqueous solution to the flotation tank 22. Non-polar organic powder from the non-polar substance recovery unit 70 enters the heating device 21 through a conveying pipe 27. The heating process causes the solution on the surface of the non-polar organic powder (including the alkaline solution, polar solvent, etc. added in the previous steps) to evaporate. The heated non-polar organic powder enters the flotation tank 22 through the inlet 23. Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats due to its hydrophobicity. The polyethylene solution containing polyethylene and wetting agent is discharged from the third liquid outlet 26. The polypropylene with higher purity is collected in the flotation tank 22, thus obtaining polypropylene.

[0093] In this embodiment, the iron powder content is 99.7%; the aluminum content in the aluminum-containing solution is 32%; the polypropylene content is 98.5%; and the polyethylene content in the polyethylene solution is 91%.

[0094] Example 2

[0095] In this embodiment, the alkaline solution is a 7 mol / L sodium hydroxide solution; the polar solvent is ethylene glycol; and the wetting agent aqueous solution is a calcium lignosulfonate aqueous solution with a mass fraction of 0.3%.

[0096] like Figure 1 As shown, the mask recycling system includes a crushing unit 40, an iron powder separation unit 50, a salt and alkali pond unit 60, a non-polar substance recovery unit 70, and a drying and flotation unit 80.

[0097] The pulverizing unit 40 includes a first blower 1, a pulverizing device, a second blower 5, and a collecting device 6 arranged sequentially from top to bottom. The pulverizing device includes a shell 28 and an inner cavity 29. A cross-cutting pulverizer 2 and a shearing pulverizer 3 are arranged sequentially from top to bottom in the inner cavity. The top of the pulverizing device has an air inlet 30. The second blower 5 is located on one side of the bottom of the pulverizing device, and the other side of the bottom of the pulverizing device has an air outlet 4 opposite to the second blower 5. The mask is exposed to air from the air inlet 30 under the force of the first blower 1. After entering the crushing device, the material is crushed by the cross-cutting crusher 2 and the shearing crusher 3 in sequence to obtain crushed mask material with a particle size of 3-5mm. The crushed mask material is screened out by the lateral wind force applied by the second blower 5 to obtain small mask powder particles with a particle size ≤0.5mm. The small mask powder particles enter the iron powder separation unit 50 through the blower outlet 4. The large mask powder particles >0.5mm that were not completely crushed after being crushed by the cross-cutting crusher 2 and the shearing crusher 3 are collected in the collection device 6 and crushed again.

[0098] The iron powder separation unit 50 includes a conveyor belt 8 and an electromagnet 7 disposed on the upper part of the conveyor belt 8. The conveyor belt 8 can be located directly below the blower outlet 4. Small particles of mask powder from the crushing unit 40 fall onto the conveyor belt 8 through the blower outlet 4. During the conveying process of the conveyor belt 8, the iron in the mask powder is attracted by the electromagnet 7 on the upper part of the conveyor belt 8. The iron powder is separated under the attraction of the magnetic force and thus adsorbed on the electromagnet 7. What remains on the conveyor belt 8 is the mask powder after iron removal. Finally, the separated iron powder and iron-removed mask powder are obtained.

[0099] The saline-alkali tank unit 60 includes a saline-alkali tank 9, which is a three-chamber saline-alkali tank. The first chamber is equipped with a powder inlet 11. Powder outlets 14 are located between the first and second chambers, and between the second and third chambers. The third chamber is equipped with a powder outlet 15. Each of the first, second, and third chambers is equipped with a first liquid inlet 10, a push rod 12, and a first liquid outlet 13. Iron-removing mask powder from the conveyor belt 8 in the iron powder separation unit 50 exits from the first chamber of the saline-alkali tank. After entering the first-chamber salt-alkali tank through the powder inlet 11, the aluminum in the iron-removing mask powder reacts with the alkaline solution in the first-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain outlet 13 in the first-chamber salt-alkali tank. However, the iron-removing mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface. It will be pushed to the powder outlet 14 between the first-chamber and second-chamber salt-alkali tanks by the push rod 12 in the first-chamber salt-alkali tank and enter the second-chamber salt-alkali tank. The residual aluminum in the iron-free mask powder reacts with the alkaline solution in the two-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain port 13 in the two-chamber salt-alkali tank. The iron-free mask powder containing polar and non-polar organic matter does not react and floats on the surface. It is then pushed by the push rod 12 in the two-chamber salt-alkali tank to the powder discharge port 14 between the two-chamber and three-chamber salt-alkali tanks, entering the third-chamber salt-alkali tank. The residual aluminum in the iron-free mask powder containing polar and non-polar organic matter... Aluminum reacts with the alkaline solution in the three-chamber salt-alkali tank to produce aluminum salt. The mixed solution containing the alkaline solution and aluminum salt is discharged from the first drain port 13 in the three-chamber salt-alkali tank. The iron-removed mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface of the liquid. It will be pushed to the powder outlet 15 of the three-chamber salt-alkali tank by the push rod 12. At this time, the aluminum-removed mask powder (with high purity of polar organic matter and non-polar organic matter) is discharged from the powder outlet 15 and enters the non-polar substance recovery unit 70.

[0100] The non-polar substance recovery unit 70 includes a dissolving tank 16, a pressure reducing device 19, and a filtration device 20. The dissolving tank 16 is provided with a second liquid inlet 17 and a second liquid outlet 18. The second liquid inlet 17 is used to add a polar solvent to the dissolving tank 16. The aluminum-free mask powder from the salt-alkali tank unit 6 is discharged from the powder outlet 15 and enters the dissolving tank 16. The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolving tank 16, while the non-polar organic matter is suspended in the solution. The resulting stratified mixture is discharged from the second liquid outlet 18 and enters the filtration device 20. It is filtered under the action of the pressure reducing device 19 to obtain a mixed liquid containing polar organic matter and a solid product. The obtained solid product is a non-polar organic matter powder.

[0101] The drying flotation unit 80 includes a heating device 21 and a flotation tank 22. The flotation tank 22 includes an inlet 23, a third liquid inlet 24, and a third liquid outlet 26. The third liquid inlet 24 is used to add a wetting agent aqueous solution to the flotation tank 22. Non-polar organic powder from the non-polar substance recovery unit 70 enters the heating device 21 through a conveying pipe 27. The heating process causes the solution on the surface of the non-polar organic powder (including the alkaline solution, polar solvent, etc. added in the previous steps) to evaporate. The heated non-polar organic powder enters the flotation tank 22 through the inlet 23. Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats due to its hydrophobicity. The mixture of polyethylene and wetting agent is discharged from the third liquid outlet 26. The flotation tank 22 collects polypropylene with higher purity, thus obtaining polypropylene.

[0102] In this embodiment, the iron powder content is 99.7%; the aluminum content in the aluminum-containing solution is 30%; the polypropylene content is 95%; and the polyethylene content in the polyethylene solution is 87%.

[0103] Example 3

[0104] In this embodiment, the alkaline solution is a sodium hydroxide solution with a concentration of 11 mol / L; the polar solvent is ethanol; and the wetting agent aqueous solution is a calcium lignosulfonate aqueous solution with a mass fraction of 0.3%.

[0105] like Figure 1 As shown, the mask recycling system includes a crushing unit 40, an iron powder separation unit 50, a salt and alkali pond unit 60, a non-polar substance recovery unit 70, and a drying and flotation unit 80.

[0106] The pulverizing unit 40 includes a first blower 1, a pulverizing device, a second blower 5, and a collecting device 6 arranged sequentially from top to bottom. The pulverizing device includes a shell 28 and an inner cavity 29. A cross-cutting pulverizer 2 and a shearing pulverizer 3 are arranged sequentially from top to bottom in the inner cavity. The top of the pulverizing device has an air inlet 30. The second blower 5 is located on one side of the bottom of the pulverizing device, and the other side of the bottom of the pulverizing device has an air outlet 4 opposite to the second blower 5. The mask is exposed to air from the air inlet 30 under the force of the first blower 1. After entering the crushing device, the material is crushed by the cross-cutting crusher 2 and the shearing crusher 3 in sequence to obtain crushed mask material with a particle size of 3-5mm. The crushed mask material is screened out by the lateral wind force applied by the second blower 5 to obtain small mask powder particles with a particle size ≤0.5mm. The small mask powder particles enter the iron powder separation unit 50 through the blower outlet 4. The large mask powder particles >0.5mm that were not completely crushed after being crushed by the cross-cutting crusher 2 and the shearing crusher 3 are collected in the collection device 6 and crushed again.

[0107] The iron powder separation unit 50 includes a conveyor belt 8 and an electromagnet 7 disposed on the upper part of the conveyor belt 8. The conveyor belt 8 can be located directly below the blower outlet 4. Small particles of mask powder from the crushing unit 40 fall onto the conveyor belt 8 through the blower outlet 4. During the conveying process of the conveyor belt 8, the iron in the mask powder is attracted by the electromagnet 7 on the upper part of the conveyor belt 8. The iron powder is separated under the attraction of the magnetic force and thus adsorbed on the electromagnet 7. What remains on the conveyor belt 8 is the mask powder after iron removal. Finally, the separated iron powder and iron-removed mask powder are obtained.

[0108] The saline-alkali tank unit 60 includes a saline-alkali tank 9, which is a three-chamber saline-alkali tank. The first chamber is equipped with a powder inlet 11. Powder outlets 14 are located between the first and second chambers, and between the second and third chambers. The third chamber is equipped with a powder outlet 15. Each of the first, second, and third chambers is equipped with a first liquid inlet 10, a push rod 12, and a first liquid outlet 13. Iron-removing mask powder from the conveyor belt 8 in the iron powder separation unit 50 exits from the first chamber of the saline-alkali tank. After entering the first-chamber salt-alkali tank through the powder inlet 11, the aluminum in the iron-removing mask powder reacts with the alkaline solution in the first-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain outlet 13 in the first-chamber salt-alkali tank. However, the iron-removing mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface. It will be pushed to the powder outlet 14 between the first-chamber and second-chamber salt-alkali tanks by the push rod 12 in the first-chamber salt-alkali tank and enter the second-chamber salt-alkali tank. The residual aluminum in the iron-free mask powder reacts with the alkaline solution in the two-chamber salt-alkali tank to form aluminum salts. The mixed solution containing the alkaline solution and aluminum salts is discharged from the first drain port 13 in the two-chamber salt-alkali tank. The iron-free mask powder containing polar and non-polar organic matter does not react and floats on the surface. It is then pushed by the push rod 12 in the two-chamber salt-alkali tank to the powder discharge port 14 between the two-chamber and three-chamber salt-alkali tanks, entering the third-chamber salt-alkali tank. The residual aluminum in the iron-free mask powder containing polar and non-polar organic matter... Aluminum reacts with the alkaline solution in the three-chamber salt-alkali tank to produce aluminum salt. The mixed solution containing the alkaline solution and aluminum salt is discharged from the first drain port 13 in the three-chamber salt-alkali tank. The iron-removed mask powder containing polar organic matter and non-polar organic matter cannot react and will float on the surface of the liquid. It will be pushed to the powder outlet 15 of the three-chamber salt-alkali tank by the push rod 12. At this time, the aluminum-removed mask powder (with high purity of polar organic matter and non-polar organic matter) is discharged from the powder outlet 15 and enters the non-polar substance recovery unit 70.

[0109] The non-polar substance recovery unit 70 includes a dissolving tank 16, a pressure reducing device 19, and a filtration device 20. The dissolving tank 16 is provided with a second liquid inlet 17 and a second liquid outlet 18. The second liquid inlet 17 is used to add a polar solvent to the dissolving tank 16. The aluminum-free mask powder from the salt-alkali tank unit 6 is discharged from the powder outlet 15 and enters the dissolving tank 16. The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolving tank 16, while the non-polar organic matter is suspended in the solution. The resulting stratified mixture is discharged from the second liquid outlet 18 and enters the filtration device 20. It is filtered under the action of the pressure reducing device 19 to obtain a mixed liquid containing polar organic matter and a solid product. The obtained solid product is a non-polar organic matter powder.

[0110] The drying flotation unit 80 includes a heating device 21 and a flotation tank 22. The flotation tank 22 includes an inlet 23, a third liquid inlet 24, and a third liquid outlet 26. The third liquid inlet 24 is used to add a wetting agent aqueous solution to the flotation tank 22. Non-polar organic powder from the non-polar substance recovery unit 70 enters the heating device 21 through a conveying pipe 27. The heating process causes the solution on the surface of the non-polar organic powder (including the alkaline solution, polar solvent, etc. added in the previous steps) to evaporate. The heated non-polar organic powder enters the flotation tank 22 through the inlet 23. Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats due to its hydrophobicity. The mixture of polyethylene and wetting agent is discharged from the third liquid outlet 26. The flotation tank 22 collects polypropylene with higher purity, thus obtaining polypropylene.

[0111] In this embodiment, the iron powder content is 99.7%; the aluminum content in the aluminum-containing solution is 32%; the polypropylene content is 94.5%; and the polyethylene content in the polyethylene solution is 88.5%.

[0112] Example 4

[0113] The method of Example 1 was followed, except that the alkaline solution was a sodium hydroxide solution with a concentration of 16 mol / L.

[0114] In this embodiment, the iron powder content is 99.7%; the aluminum content in the aluminum-containing solution is 31%; the polypropylene content is 92%; and the polyethylene content in the polyethylene solution is 89%.

[0115] As can be seen from the above embodiments, the method described in this invention can recover various components from masks, and can obtain iron powder, aluminum-containing solution, polypropylene and polyethylene solution with high content. The recovered materials can be reused in multiple ways, realize efficient recycling of resources, and improve the economic value and environmental benefits of the entire recycling process.

[0116] It should be understood that any parts not described in detail in this specification belong to the prior art.

[0117] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A mask recycling system, characterized in that, The mask recycling system includes: The crushing unit (40) is used to crush and screen the mask to obtain mask powder containing iron, aluminum, polar organic matter and non-polar organic matter; Iron powder separation unit (50) is used to remove iron from the mask powder to obtain iron-free mask powder and iron powder; The salt-alkali pool unit (60) is used to remove aluminum from the iron-free mask powder to obtain aluminum-free mask powder; The non-polar substance recovery unit (70) is used to separate the polar organic matter in the aluminum-free mask powder to obtain a non-polar organic matter powder containing polyethylene and polypropylene. The drying flotation unit (80) is used to separate polyethylene from non-polar organic powder to obtain polypropylene; The salt and alkali tank unit (60) includes a salt and alkali tank (9), which has a powder inlet (11), a first liquid inlet (10), a first liquid outlet (13) and a powder outlet (15). A push rod (12) is provided at the powder inlet (11), and the first liquid inlet (10) is used to add alkali solution to the salt and alkali tank (9). Iron-free mask powder from the iron powder separation unit (50) enters the salt-alkali pool (9) through the powder inlet (11). The aluminum in the iron-free mask powder reacts with the alkali solution in the salt-alkali pool (9), and the resulting mixed solution is discharged from the first drain outlet (13). The iron-free mask powder that cannot react floats on the liquid surface and is driven to the powder outlet (15) by the push rod (12) to be discharged, thus obtaining aluminum-free mask powder. Alternatively, the salt-alkali tank (9) is a multi-chamber salt-alkali tank, with a powder discharge port (14) between two adjacent salt-alkali tanks. The iron removal mask powder floating on the liquid surface enters the next salt-alkali tank from the upper chamber through the powder discharge port (14) under the action of the push rod (12), and is finally discharged from the powder outlet (15). The non-polar substance recovery unit (70) includes a dissolving tank (16), a pressure reducing device (19), and a filtration device (20). The dissolving tank (16) is provided with a second liquid inlet (17) and a second liquid outlet (18). The second liquid inlet (17) is used to add a polar solvent to the dissolving tank (16). The aluminum-free mask powder from the saline-alkali tank unit (60) is discharged from the powder outlet (15) and enters the dissolution tank (16). The polar organic matter in the aluminum-free mask powder dissolves in the polar solvent in the dissolution tank (16), while the non-polar organic matter is suspended in the solution. The resulting mixture is discharged from the second drain outlet (18) and enters the filtration device (20). It is filtered under the action of the pressure reducing device (19), and the resulting solid product is non-polar organic powder. The drying flotation unit (80) includes a heating device (21) and a flotation tank (22). The flotation tank (22) includes an inlet (23), a third liquid inlet (24), and a third liquid outlet (26). The third liquid inlet (24) is used to add a wetting agent aqueous solution to the flotation tank (22). Non-polar organic powder from the non-polar substance recovery unit (70) enters the heating device (21) through the conveying pipe (27). The solution on the surface of the non-polar organic powder evaporates through heating treatment. The heated non-polar organic powder enters the flotation tank (22) from the inlet (23). Polyethylene sinks under the action of the wetting agent aqueous solution, while polypropylene floats. The mixture of polyethylene and wetting agent is discharged from the third drain (26) to obtain polypropylene. Alternatively, a fan (25) may be provided in the flotation tank (22) to accelerate the flotation of polypropylene.

2. The mask recycling system according to claim 1, characterized in that, The crushing unit (40) includes a first blower (1), a crushing device, a second blower (5) and a collecting device (6) arranged sequentially from top to bottom. The crushing device includes a shell (28) and an inner cavity (29). A cross-cutting crusher (2) and a shearing crusher (3) are arranged sequentially from top to bottom in the inner cavity. The top of the crushing device has an air inlet (30). The second blower (5) is located on one side of the bottom of the crushing device. The other side of the bottom of the crushing device has an air outlet (4) opposite to the second blower (5). The mask enters the crushing device through the air inlet (30) under the action of the first blower (1). After being crushed by the cross-cutting crusher (2) and the shear crusher (3) in sequence, the crushed mask material with a particle size of 3-5mm is obtained. The crushed mask material is screened out into small mask powder with a particle size of ≤0.5mm under the action of the cross-wind force applied by the second blower (5). The small mask powder enters the iron powder separation unit (50) through the air outlet (4). Alternatively, the collection device (6) is used to collect large-particle mask powder with a particle size > 0.5 mm that has been screened out under the action of the lateral wind force applied by the second blower (5).

3. The mask recycling system according to claim 2, characterized in that, The iron powder separation unit (50) includes a conveyor belt (8) and an electromagnet (7) disposed on the upper part of the conveyor belt (8). The mask powder from the crushing unit (40) arrives on the conveyor belt (8) through the blower outlet (4), and the iron in the mask powder is adsorbed by the electromagnet (7) to obtain iron powder and de-iron mask powder.

4. A method for recycling face masks, wherein the method is implemented using the face mask recycling system described in any one of claims 1-3, characterized in that, The method for recycling these masks includes: The mask is crushed and screened to obtain mask powder, which contains iron, aluminum, polar organic matter and non-polar organic matter; Iron is separated from the mask powder to obtain iron-free mask powder and iron powder; The aluminum in the de-ferrous powder is separated and removed to obtain de-aluminized mask powder; The polar organic matter in the aluminum-free mask powder is removed to obtain a non-polar organic powder, which contains polyethylene and polypropylene. Polyethylene was separated from the non-polar organic powder to obtain polypropylene.

5. The method according to claim 4, characterized in that, The process of separating and removing aluminum from iron-free powder to obtain aluminum-free mask powder includes: reacting the aluminum in the iron-free mask powder with an alkaline solution; the unreacted iron-free mask powder floats on the surface of the liquid and is then discharged to obtain aluminum-free mask powder. Alternatively, the alkaline solution may be a sodium hydroxide solution and / or a potassium hydroxide solution.

6. The method according to claim 4, characterized in that, The process of removing polar organic matter from aluminum-free mask powder to obtain non-polar organic matter powder includes: mixing aluminum-free mask powder with a polar solvent, dissolving the polar organic matter in the polar solvent, and suspending the non-polar organic matter in the solution, and then filtering under reduced pressure to obtain a solid product, which is non-polar organic matter powder. Alternatively, the polar solvent may be ethylene glycol and / or dimethyl sulfoxide.

7. The method according to claim 4, characterized in that, The process of separating polyethylene from non-polar organic powder to obtain polypropylene includes: heating the non-polar organic powder to volatilize the surface of the non-polar organic powder, then mixing the heated non-polar organic powder with an aqueous wetting agent solution, where polyethylene sinks under the action of the aqueous wetting agent solution and polypropylene floats, and polypropylene is obtained after separation. Alternatively, the wetting agent aqueous solution is an aqueous solution of calcium lignosulfonate and / or an aqueous solution of sodium dodecyl sulfate.

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