Tailings recovery method for self-supporting dry functional membrane

Abstract

The present invention relates to a tailings recycling method for a self-supporting dry functional membrane, comprising the following steps: obtaining tailings and crushing them; the fineness of the crushed tailings is 10 mesh to 5000 mesh; mixing the crushed tailings with dry mixed material powder to prepare a mixture; and performing calendering and trimming treatments on the mixture to prepare a self-supporting dry functional membrane. The tailings recycling method can achieve effective recycling of tailings while making the prepared self-supporting dry functional membrane meet the requirements of mechanical and electrical properties, and has a positive effect on saving resources and protecting the environment.

Description

Technical Field

[0001] The invention relates to the technical field of resource recovery, and in particular to a method for recovering tailings of a self-supporting dry functional membrane. Background Art

[0002] The preparation process of functional membranes of energy storage devices usually includes wet process and dry process. Among them, the wet process refers to mixing the binder and active electrode components with the solvent to prepare a slurry, then applying the slurry to the current collector, and forming a film on the current collector after drying to remove the solvent. The dry process refers to directly dry mixing the binder and the active electrode components, and then forming the dry mixture into a film layer by calendering, and then compounding it with the current collector.

[0003] For the dry process, since the dry mixed powder is directly rolled into a self-supporting dry functional membrane, the two sides of the self-supporting dry functional membrane are basically impossible to be neat due to the fluidity of the dry mixed powder. Therefore, before the self-supporting dry functional membrane is rolled up, a trimming step must be performed to remove the uneven edges to form tailings. Usually, the proportion of tailings can reach 5% to 15% of the total mass of the dry mixed powder, resulting in a waste of raw materials. Summary of the invention

[0004] Based on this, the present invention provides a tailings recovery method of a self-supporting dry functional membrane capable of recovering and reusing the tailings.

[0005] A first aspect of the present invention provides a method for recovering tailings of a self-supporting dry functional membrane, comprising the following steps:

[0006] Obtain tailings and crush them; the fineness of the crushed tailings is 10 mesh to 5000 mesh;

[0007] The crushed tailings are mixed with dry mixed material powder to prepare a mixed material;

[0008] The mixed material is subjected to calendering and trimming treatments to prepare a self-supporting dry functional membrane.

[0009] In one of the embodiments, in the mixture, the mass percentage of the tailings is 1% to 30%.

[0010] In one embodiment, the mixing time is 3 min to 60 min.

[0011] In one embodiment, the device used for the calendering process includes a plurality of calendering rollers and a feeding device, a feeding area is formed between two adjacent calendering rollers, and the feeding device extends to the feeding area;

[0012] The feeding device comprises a first powder baffle, a first tailing baffle, a second tailing baffle and a second powder baffle which are arranged in sequence;

[0013] Wherein, the channel formed between the first powder baffle and the first tailing baffle is used to transport dry mixed powder;

[0014] The channel formed between the first tailing baffle plate and the second tailing baffle plate is used to transport the mixed material;

[0015] The channel formed between the second powder baffle and the second tailing baffle is used to transport dry mixed powder.

[0016] In one embodiment, the distance between the first powder baffle and the second powder baffle is D1, the distance between the first powder baffle and the first tailing baffle is D2, and the distance between the second powder baffle and the second tailing baffle is D3;

[0017] D2:D1=(0.05~0.4):1, D3:D1=(0.05~0.4):1.

[0018] In one embodiment, along the feeding direction, the first powder baffle extends to the feeding area at a depth of H1, the first tailing baffle extends to the feeding area at a depth of H2, the second tailing baffle extends to the feeding area at a depth of H4, and the second powder baffle extends to the feeding area at a depth of H3;

[0019] H2:H1=(0.4~0.8):1, H4:H3=(0.4~0.8):1.

[0020] In one embodiment, the bulk density of the active material in the dry mixed powder is 0.1 to 3 g / cm 3 .

[0021] In one embodiment, in the dry blend powder, the average particle size (D50) of the active material is 1 μm to 30 μm.

[0022] In one embodiment, the speed ratio of the calendering roller is 1:(1.05-2).

[0023] In one embodiment, the temperature of the calendering treatment is 50°C to 250°C.

[0024] In one of the embodiments, the thickness of the self-supporting dry functional membrane is 50 μm to 400 μm.

[0025] A second aspect of the present invention provides a method for preparing a self-supporting dry functional membrane, comprising the following steps:

[0026] S1, performing calendering and trimming treatments on the dry mixed powder, collecting the film and tailings respectively, and rolling up the film;

[0027] S2, preparing a self-supporting dry functional membrane by using the tailings collected in step S1 according to the recovery method described in the first aspect, collecting the membrane and the tailings respectively, and rolling up the membrane;

[0028] S3. Repeat step S2 once or multiple times with the tailings collected in step S2.

[0029] When recycling the tailings of the self-supporting dry functional membrane, they must first be crushed into tailing powder and then rolled into dry membranes. After the tailings are crushed, the bonding properties of the binder contained in them are reduced. At this time, if they are directly rolled into a film, the membrane strength is insufficient and large or small cracks are prone to appear. Even very small cracks are easy to expand during the process of winding the membrane, resulting in a low yield rate of the membrane, or even the inability to continue production. At the same time, the mechanical and electrical properties of the prepared self-supporting dry functional membrane are also reduced.

[0030] Based on this, the present invention has found through research that when the tailings are crushed, the fineness of the crushed tailings is reasonably controlled, and then the crushed tailings are mixed with the dry mixed material powder to prepare a self-supporting dry functional membrane. While achieving effective recycling of the tailings, the prepared self-supporting dry functional membrane meets the production process and mechanical and electrical performance requirements of the membrane, which has a positive effect on saving resources and protecting the environment. In addition, the tailings recycling method has a high recycling rate for the tailings, can reduce the production cost of the self-supporting dry functional membrane, and has little environmental pollution, is easy to operate, and is easy to realize industrialization.

[0031] Furthermore, the tailings recovery method is integrated with the preparation steps of the self-supporting dry functional membrane, which can continuously digest the tailings and simultaneously realize the recovery of tailings and the preparation of new self-supporting dry functional membranes, so that the amount of excess tailings in the entire self-supporting dry functional membrane production line is close to 0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A process flow chart of a method for recovering tailings of a self-supporting dry functional membrane according to an embodiment of the present invention;

[0033] Figure 2 A front view of a device used for calendering treatment in one embodiment of the present invention;

[0034] Figure 3 It is a top view of the device used for calendering treatment in one embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following is a further detailed description of the tailings recovery method of the self-supporting dry functional membrane of the present invention in conjunction with specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0037] In the present invention, "the first aspect", "the second aspect", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0038] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0039] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0040] The percentage content involved in the present invention, unless otherwise specified, refers to mass percentage for solid-liquid mixing and solid-solid mixing, and refers to volume percentage for liquid-liquid mixing.

[0041] The percentage concentrations involved in the present invention, unless otherwise specified, refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of the component.

[0042] The temperature parameters in the present invention, if not specifically limited, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument.

[0043] In the present invention, "dry mixed powder" has the same meaning as "normal material", which refers to the raw material for preparing the self-supporting dry functional membrane without adding tailings, usually including active materials, binders and additives. Without limitation, the additives may be conductive agents, pore forming agents, bonding enhancers, etc.

[0044] In the present invention, "tail material" can refer to the edge material cut off after the dry mixed material powder is subjected to one or more calendering and trimming treatments, and can also refer to the edge material obtained after calendering and trimming treatments during one or more cycles of the preparation method of the self-supporting dry functional membrane according to the present invention.

[0045] The present invention provides a method for recovering tailings of a self-supporting dry functional membrane, the process flow of which is as follows: Figure 1 As shown, the following steps are included:

[0046] Obtain tailings and crush them; the fineness of the crushed tailings is 10 mesh to 5000 mesh;

[0047] The crushed tailings are mixed with dry mixed material powder to prepare a mixed material;

[0048] The mixed material is subjected to calendering and trimming treatments to prepare a self-supporting dry functional membrane.

[0049] In the above-mentioned tailings recovery method, the tailings need to be crushed, and the fineness after crushing should be reasonably controlled to be 10 mesh to 5000 mesh. If the fineness after crushing is too small, that is, the crushing strength is too high, the bonding effect will be significantly reduced during the subsequent mixing process, resulting in a decrease in the mechanical strength and electrical properties of the self-supporting dry functional membrane produced; if the fineness after crushing is too large, that is, the crushing strength is too small, flaky tailings will remain, which will be difficult to bond firmly with the dry mixed material powder, and will also result in a decrease in the mechanical strength and electrical properties of the self-supporting dry functional membrane produced. Furthermore, the fineness after crushing is 100 mesh to 1000 mesh.

[0050] Without limitation, the pulverization method may be mechanical milling, impact milling, air flow milling, etc.

[0051] In one specific example, the mass percentage of tailings in the mixture is 1% to 30%. The mass percentage of tailings is reasonably controlled to ensure the mechanical strength and electrical properties of the self-supporting dry functional membrane while recycling as much tailings as possible. Furthermore, the mass percentage of tailings in the mixture is 5% to 20%.

[0052] In one specific example, the mixing time is 3 minutes to 60 minutes. Without limitation, the mixing method can be container rotation, forced stirring, air flow mixing, etc.

[0053] Among them, the container rotation type refers to the material in the container rotating around the axis, mainly under the action of gravity, undergoing complex motion and mixing with each other. According to the shape of the container, it can be cylindrical, drum, vertical, double cone and V-shaped. According to the shape of the blade, the forced stirring type can be paddle, spiral ribbon, spiral blade, etc. Airflow mixing refers to the use of pulsed high-speed airflow to make the material turbulent, or the use of high-pressure airflow to form convection motion in the container to mix the material, such as fluidization type, pulse swirl type, etc.

[0054] In addition, cracks in self-supporting dry functional diaphragms usually appear at the edges, in a wavy or jagged shape, which will form a stress concentration area. Although the edge trimming process is performed, if the edge trimming process is incomplete, the remaining tiny cracks can easily expand from the edge to form large cracks, and even cause the diaphragm to break, which is not conducive to the continuous winding of the self-supporting diaphragm.

[0055] Based on this, the present invention further optimizes the steps of the tailings recovery method, adopts a three-stage feeding system of "dry blend powder-mixed material-dry blend powder", feeds dry blend powder on both sides, and feeds mixed material in the middle, which is conducive to maintaining the edge strength of the film and preventing the expansion of the jagged edge. At the same time, when the trimming process is performed in the tailings recovery method, the new tailings formed are mainly or entirely dry blend powder, so when the recycling is repeated (see Figure 1 ), which can maintain a high consistency between the front and rear diaphragms and form a sustainable production cycle.

[0056] In one specific example, the calendering process uses an apparatus such as Figures 2-3 As shown, it includes a plurality of calenders 100 and a feeding device 200, a feeding area is formed between two adjacent calender rollers 100, and the feeding device 200 extends to the feeding area;

[0057] The feeding device 200 comprises a first powder baffle 201, a first tailing baffle 202, a second tailing baffle 204 and a second powder baffle 203 which are arranged in sequence;

[0058] The channel formed between the first powder baffle 201 and the first tailing baffle 202 is used to transport dry mixed powder;

[0059] The channel formed between the first tailing baffle plate 202 and the second tailing baffle plate 204 is used to transport the mixed material;

[0060] The channel formed between the second powder baffle 203 and the second tailing baffle 204 is used to transport dry mixed powder.

[0061] In one specific example, see Figure 3, the distance between the first powder baffle 201 and the second powder baffle 203 is D1, the distance between the first powder baffle 201 and the first tailing baffle 202 is D2, and the distance between the second powder baffle 203 and the second tailing baffle 204 is D3. D2:D1=(0.05~0.4):1, D3:D1=(0.05~0.4):1. If D2:D1 or D3:D1 is too small, that is, the feeding area of ​​the dry mixed powder is too small, firstly, it is inconvenient to feed the dry mixed powder, and secondly, the mixed material may be cut during trimming, so that the new tailing contains the old tailing, which is not conducive to continued recycling; if D2:D1 or D3:D1 is too large, that is, the mixed material feeding area is too small, so that the capacity of tailing recycling is limited. Further, D2:D1=(0.2~0.4):1, D3:D1=(0.2~0.4):1.

[0062] In one specific example, D3 = D2.

[0063] In one specific example, see Figure 2 , along the feeding direction, the depth of the first powder baffle 201 extending to the feeding area is H1, the depth of the first tailing baffle 202 extending to the feeding area is H2, the depth of the second tailing baffle 204 extending to the feeding area is H4, and the depth of the second powder baffle 203 extending to the feeding area is H3. In order to ensure the film-forming effect, it is necessary to make the dry blend powder and the mixed material reach a certain degree of mutual contact and accumulation before calendering, so it is necessary to control H2

[0064] In one specific example, H1=H3, H2=H4.

[0065] Furthermore, during the calendering process, in one specific example, the calendering temperature is 50° C. to 250° C. This can fully soften the binder in the dry mixed powder, generate hot viscosity, and ensure film-forming properties.

[0066] ​In one specific example, the speed ratio of the calendering roller is 1:(1.05~2). During calendering, the powder material is combined into a membrane under the rotational friction and extrusion force of the high-temperature roller. The larger the speed ratio, the greater the shear force, but too high a speed ratio will cause the surface of the entire membrane to be uneven, and even form periodic stripes. Using a suitable calendering roller speed ratio can enhance the penetration and bonding strength of the tail material to the dry blend powder, and at the same time make the surface of the manufactured membrane smooth. Furthermore, the speed ratio of the calendering roller is 1:(1.1~1.5).

[0067] In one specific example, the tap density of the active material in the dry blend powder is 0.1 to 3 g / cm 3 .

[0068] In one specific example, the average particle size (D50) of the active material in the dry blend powder is 1 μm to 30 μm.

[0069] In one specific example, the thickness of the self-supporting dry functional film is 50 μm to 400 μm.

[0070] The present invention also provides a method for preparing a self-supporting dry functional membrane, comprising the following steps:

[0071] S1, calendering and trimming the dry mixed powder, collecting the film and tailings respectively, and rolling up the film;

[0072] S2, preparing a self-supporting dry functional membrane using the tailings collected in step S1 according to the above tailings recovery method, collecting the membrane and the tailings respectively, and rolling up the membrane;

[0073] S3. Repeat step S2 once or multiple times with the tailings collected in step S2.

[0074] Starting from dry mixed powders and in combination with a tailings recovery method, a self-supporting dry functional membrane is produced, so that the collected tailings can be continuously recycled and reused.

[0075] The following are specific examples.

[0076] Example 1

[0077] This embodiment is a tailings recovery method for an activated carbon self-supporting dry functional membrane, wherein the tap density of the activated carbon as the main component is 0.4 g / cm 3 , the average particle size (D50) is 6μm.

[0078] Here are the steps:

[0079] (1) The tailings of the activated carbon membrane are crushed by a mechanical mill to obtain a tailings powder with a fineness of 500 mesh;

[0080] (2) The tailing powder was mixed with the normal material of the activated carbon membrane at a ratio of 15wt%, the mixing equipment was a V-type mixer, and the mixing time was 20min;

[0081] (3) See Figure 2 and 3 , set the first powder baffle, the first tailing baffle, the second tailing baffle and the second powder baffle so that D2:D1=D3:D1=0.15:1, H2:H1=H3:H4=0.6:1;

[0082] (4) calendering, the calendering temperature is 100° C., and the speed ratio of the calendering roller is set to 1:1.2;

[0083] (5) Perform edge trimming and roll up the film.

[0084] The thickness of the activated carbon self-supporting electrode membrane recycled from the tailings is 120 μm. At the same time, the entire mixing-calendering-winding production process can be continuously circulated.

[0085] The performance test of the activated carbon self-supporting dry functional membrane of this embodiment is carried out:

[0086] a) The tensile strength was tested according to GB / T 1040.3-2006 / ISO 527-3:2018 (the standard width of the test strip was 20 mm and the length was 180 mm). The results were as follows: the tensile strength in the length direction (longitudinal direction) was 0.205 MPa; the tensile strength in the width direction (transverse direction) was 0.131 MPa.

[0087] b) The volume resistivity of the electrode film was measured using multiple probes and the result was 0.52 Ω·cm.

[0088] c) Use two cylindrical metal clamps with a diameter of 14 mm to clamp the electrode film from top to bottom and apply a certain pressure to measure its penetration resistance, which is 32 mΩ.

[0089] The results are summarized in Table 1.

[0090] Example 2-1

[0091] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane. The tailings and steps used are the same as those of Example 1, with the main difference being that the fineness of the obtained tailings powder is 100 mesh.

[0092] The entire mixing-calendering-winding production process can be recycled continuously.

[0093] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0094] Example 2-2

[0095] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane. The tailings and steps used are the same as those of Example 1, with the main difference being that the fineness of the obtained tailings powder is 2000 mesh.

[0096] The entire mixing-calendering-winding production process can be recycled continuously.

[0097] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0098] Example 3-1

[0099] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane. The tailings and steps used are the same as those in Embodiment 1, with the main difference being that the mixing ratio of tailings powder to normal material is 5wt%.

[0100] The entire mixing-calendering-winding production process can be recycled continuously.

[0101] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0102] Example 3-2

[0103] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane. The tailings and steps used are the same as those in Embodiment 1, with the main difference being that the mixing ratio of tailings powder to normal material is 30 wt %.

[0104] At the same time, the entire mixing-calendering-winding production process can be recycled continuously.

[0105] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0106] Example 4-1

[0107] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane. The tailings and steps used are the same as those in Embodiment 1, with the main difference being that the speed ratio of the calendering roller is set to 1:1.5.

[0108] The entire mixing-calendering-winding production process can be recycled continuously.

[0109] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0110] Example 5-1

[0111] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane, and the steps are the same as those of Embodiment 1, with the main difference being that D2:D1=D3:D1=0.3:1.

[0112] The entire mixing-calendering-winding production process can be recycled continuously.

[0113] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0114] Example 5-2

[0115] This embodiment is a method for recovering tailings of an activated carbon self-supporting dry functional membrane, and the steps are the same as those of Embodiment 1, with the main difference being that: H2:H1=H4:H3=0.8:1.

[0116] The entire mixing-calendering-winding production process can be recycled continuously.

[0117] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0118] Example 6-1

[0119] This embodiment is a method for recovering tailings of an artificial graphite self-supporting dry functional membrane. The steps are the same as those in Embodiment 1, except that the activated carbon membrane is replaced by an artificial graphite membrane, and the tap density of the main component material, artificial graphite, is 1.0 g / cm 3 The average particle size (D50) is 17 μm; the calendering temperature is 180°C.

[0120] The entire mixing-calendering-winding production process can be recycled continuously.

[0121] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0122] Example 6-2

[0123] This embodiment is a method for recovering tailings of a lithium iron phosphate self-supporting dry functional membrane. The steps are the same as those in Example 1, except that the activated carbon membrane is replaced by a lithium iron phosphate membrane, and the tap density of the main component material, lithium iron phosphate, is 1.5 g / cm 3 , the average particle size (D50) is 5 μm; the calendering temperature is 160°C.

[0124] At the same time, the entire mixing-calendering-winding production process can be recycled continuously.

[0125] The electrode membrane performance was tested according to the same testing method as in Example 1. The results are summarized in Table 1.

[0126] Table 1

[0127]

[0128] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The above-described embodiments only express several implementation methods of the present invention, which are convenient for understanding the technical solutions of the present invention in detail, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the contents of the attached claims, and the description and drawings can be used to interpret the contents of the claims.

Claims

1. A method for recovering tailings of a self-supporting dry functional membrane, characterized in that: The steps include: Obtain tailings and crush them; the fineness of the crushed tailings is 10 mesh to 5000 mesh; The crushed tailings are mixed with dry mixed powder to prepare a mixture; the dry mixed powder includes a binder and an active electrode component; The mixed material is subjected to calendering and trimming treatment to prepare a self-supporting dry functional membrane; The device used for the calendering process includes a plurality of calendering rollers and a feeding device, a feeding area is formed between two adjacent calendering rollers, and the feeding device extends to the feeding area; The feeding device comprises a first powder baffle, a first tailing baffle, a second tailing baffle and a second powder baffle which are arranged in sequence; Wherein, the channel formed between the first powder baffle and the first tailing baffle is used to transport dry mixed powder; The channel formed between the first tailing baffle plate and the second tailing baffle plate is used to transport the mixed material; The channel formed between the second powder baffle and the second tailing baffle is used to transport dry mixed powder; The distance between the first powder baffle and the second powder baffle is D1, the distance between the first powder baffle and the first tailing baffle is D2, and the distance between the second powder baffle and the second tailing baffle is D3; D2:D1=(0.05~0.4):1, D3:D1=(0.05~0.4):1; Along the feeding direction, the depth of the first powder baffle extending to the feeding area is H1, the depth of the first tailing baffle extending to the feeding area is H2, the depth of the second tailing baffle extending to the feeding area is H4, and the depth of the second powder baffle extending to the feeding area is H3; H2:H1=(0.4~0.8):1, H4:H3=(0.4~0.8):

1.

2. The method for recycling tailings of a self-supporting dry functional membrane according to claim 1, characterized in that: In the mixed material, the mass percentage of the tailings is 1% to 30%.

3. The method for recycling tailings of a self-supporting dry functional membrane according to claim 1, characterized in that: The fineness of the tailings after crushing is 10 mesh to 1000 mesh.

4. The method for recycling tailings of a self-supporting dry functional membrane according to claim 1, characterized in that: D2:D1=(0.2~0.4):1, D3:D1=(0.2~0.4):

1.

5. The method for recycling tailings of a self-supporting dry functional membrane according to claim 1, characterized in that: H2:H1=(0.5~0.7):1, H4:H3=(0.5~0.7):

1.

6. The method for recycling tailings of a self-supporting dry functional membrane according to any one of claims 1 to 5, characterized in that: The tap density of the active material in the dry mixed powder is 0.1 to 3 g / cm 3 .

7. The method for recycling tailings of a self-supporting dry functional membrane according to any one of claims 1 to 5, characterized in that: In the dry mixed powder, the average particle size of the active material is 1 μm to 30 μm.

8. The method for recycling tailings of a self-supporting dry functional membrane according to any one of claims 1 to 5, characterized in that: The speed ratio of the calendering roller is 1:(1.05-2).

9. The method for recycling tailings of a self-supporting dry functional membrane according to any one of claims 1 to 5, characterized in that: The temperature of the calendering treatment is 50°C to 250°C.

10. A method for preparing a self-supporting dry functional membrane, characterized in that: The steps include: S1, performing calendering and trimming treatments on the dry mixed powder, collecting the film and tailings respectively, and rolling up the film; S2, preparing a self-supporting dry functional membrane by using the tailings collected in step S1 according to the recovery method described in any one of claims 1 to 9, collecting the membrane and the tailings respectively, and rolling up the membrane; S3. Repeat step S2 once or multiple times with the tailings collected in step S2.

Images