Separation and recovery method of waste composite material metering box

Abstract

The invention discloses a separation and recovery method for a waste composite material metering box, and relates to the field of metering box recovery, and the method comprises the following steps: S1, recovering the waste composite material metering box; s2, the waste composite material metering box is subjected to multi-stage crushing, and composite powder containing resin powder, filler and glass fibers of different lengths is obtained; s3, the composite powder is screened through preset multiple stages of screens, regenerated powder intercepted on each stage of screen is obtained, and the hole diameters of the multiple stages of screens are gradually reduced from the first stage to the last stage in the advancing direction of the composite powder; wherein the length distribution of the glass fibers in the composite powder is adjusted by adjusting and controlling the technological parameters of the multi-stage crushing in the step S2, and the content of the glass fibers in the regenerated powder obtained on each stage of screen is adjusted by adjusting and controlling the aperture of each stage of screen. According to the invention, the powder can be directionally graded, and the powder with stable performance and high application value can be recycled.

Description

Technical Field

[0001] This invention relates to the field of metering box recycling, and specifically to a method for separating and recycling waste composite material metering boxes. Background Technology

[0002] In recent years, composite materials have replaced metals as the widely used enclosure material in power distribution systems. Therefore, metering boxes are usually made of thermosetting composite materials such as glass fiber reinforced unsaturated polyester resin and epoxy resin, which have the characteristics of high mechanical properties, good environmental resistance and high electrical insulation level.

[0003] With equipment upgrades, a large number of composite material metering boxes that have reached the end of their service life are being decommissioned. Currently, the common physical recycling methods for waste metering boxes mainly rely on mechanical crushing processes. Existing technologies primarily involve pulverizing composite material metering box waste. However, the metering boxes have thick walls, complex structures, and high fiberglass content, making them prone to jamming and severe blade wear with traditional crushing equipment. Furthermore, the complex composition of the pulverized material makes efficient material separation through conventional screening difficult, resulting in unstable performance of the recycled products and low application value of the recycled powder. Summary of the Invention

[0004] This invention aims to address, to a certain extent, one of the technical problems in related technologies. To this end, this invention provides a method for separating and recycling waste composite material metering boxes, which can perform directional classification of powders and recover powders with stable performance and high application value.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for separating and recycling waste composite material metering boxes includes the following steps: S1. Metering box for recycling waste composite materials; S2. The waste composite material metering box is crushed in multiple stages to obtain composite powder containing resin powder, filler and glass fiber of different lengths. S3. The composite powder is sieved through a preset multi-stage sieve to obtain the recycled powder retained on each sieve. The aperture of the multi-stage sieve gradually decreases from the first stage to the last stage along the direction of travel of the composite powder. Specifically, the length distribution of glass fibers in the composite powder is adjusted by regulating the process parameters of multi-stage crushing in step S2, and the content of glass fibers in the recycled powder obtained on each stage of the screen is adjusted by regulating the aperture of each stage of the screen.

[0006] In this application, the applicant discovered that resins and fillers in waste composite materials are more easily crushed than glass fibers. Brittle thermosetting resins and fillers are easily pulverized into fine powder under high-speed impact, while tough glass fibers are mainly cut rather than completely pulverized. The fracture length is actively controlled by adjusting the process parameters of multi-stage crushing. Specifically, by adjusting the process parameters, different composite powders with either long or short glass fibers as the main components are produced preferentially. The impact energy under high strain rates is precisely controlled, achieving decoupled control between "resin pulverization" and "fiber shortening." This solves the problem of random and uncontrollable glass fiber length distribution in powders produced by existing crushing processes, transforming the crushing process from uncontrollable to controllable and designable process steps. Specifically, process parameters can include the selection of crushing equipment, the power of the crushing equipment, the crushing time, and the number of cycles in the crushing process. Furthermore, by setting up multi-stage sieves with progressively smaller apertures from the first to the last stage, not only can the composite powder be graded according to particle size, but the content of glass fibers intercepted by each sieve can also be precisely controlled based on the different lengths of glass fibers produced by the aforementioned multi-stage crushing. Fine resin and filler powders easily pass through various levels of sieves, while glass fibers longer than the sieve apertures are easily trapped on the corresponding sieves. By adjusting the aperture of each sieve level, the glass fiber content in the recycled powder trapped on each sieve can be controlled. That is, large-aperture sieves trap long fibers to obtain high-fiber powder, while small-aperture sieves mainly collect fine powder and short fibers that pass through large-aperture sieves to obtain low-fiber powder. Ultimately, this achieves directional classification of the composite powder, and the composition of the recovered powder is controllable, resulting in stable performance and high application value.

[0007] Optionally, the multi-stage screen includes a first vibrating screen, a second vibrating screen, a third vibrating screen, a fourth vibrating screen, a fifth vibrating screen, a sixth vibrating screen, and a seventh vibrating screen arranged in sequence, and the composite powder passes through the first vibrating screen to the seventh vibrating screen in sequence.

[0008] The sequential arrangement of the first, second, third, fourth, fifth, sixth, and seventh vibrating screens ensures that materials pass through multiple screens in sequence, preventing material blockage or backflow. Each screening stage further purifies or classifies the product from the previous stage, offering greater stability than single-stage screening and facilitating automated continuous production. Furthermore, the screen body of the vibrating screen can vibrate at high frequency, resulting in high screening efficiency.

[0009] Optionally, the first vibrating screen has a mesh size of 20, the second vibrating screen has a mesh size of 60, the third vibrating screen has a mesh size of 100, the fourth vibrating screen has a mesh size of 150, the fifth vibrating screen has a mesh size of 200, the sixth vibrating screen has a mesh size of 250, and the seventh vibrating screen has a mesh size of 300.

[0010] The seven-stage sieve system, ranging from 20 to 300 mesh, forms a continuous sorting channel, enabling the step-by-step separation of a mixture containing glass fibers of varying lengths, resin powder, and filler powder, which has undergone initial crushing. The upper coarse-mesh sieve preferentially traps long glass fibers that provide material reinforcement; the middle sieve separates intermediate products with varying proportions of long glass fibers and resin; and the lower fine-mesh sieve primarily collects resin powder. Through this specific sieving process, the composite powder is separated into recycled powders with different particle sizes and compositions.

[0011] Optionally, in step S2, the multi-stage crushing includes pre-crushing, coarse crushing, and fine crushing performed sequentially. After the pre-crushing, the waste composite material metering box forms sheet-like or block-like materials with a length and width of 30-120 mm. After the coarse crushing, the sheet-like or block-like materials form intermediate materials with a particle size of 10-40 mm. After the fine crushing, the intermediate materials form composite powder with a particle size of 2-10 mm.

[0012] The multi-stage crushing process employs a series of pre-crushing, coarse crushing, and fine crushing steps to achieve progressive crushing of waste composite material metering boxes. Specifically, pre-crushing first processes the complete box into 30-120 mm sheet or block materials, solving the problem of its irregular structure and difficulty in direct crushing; then coarse crushing reduces the particle size of the sheet or block materials to 10-40 mm; finally, fine crushing refines the material to 2-10 mm, forming composite powder. This effectively avoids problems such as equipment jamming or uneven crushing caused by direct single-equipment crushing in existing technologies, ensuring crushing efficiency and product quality.

[0013] Optionally, the pre-crushing includes: using a cutting device to slot and cut the waste composite metering box to form sheet-like or block-like materials; the coarse crushing includes: using a twin-shaft shredder, shear crusher or hammer crusher to crush the sheet-like or block-like materials to form intermediate materials.

[0014] Waste metering bins are large and complex in structure. Pre-crushing involves directional grooving and cutting them into flake / block materials, reducing the pressure on subsequent crushing equipment. Directly crushing large, high-strength metering bins would cause severe impact and wear on the crushing equipment blades. Distributing the crushing process across three stages of equipment reduces blade wear on each stage. Furthermore, the intermediate material obtained after coarse crushing provides a suitable feed size for subsequent fine crushing equipment.

[0015] Optionally, the fine crushing includes: crushing intermediate materials into composite powder using a high-speed pulverizer, wherein the high-speed pulverizer includes a main shaft and blades fixedly connected to the main shaft, and the rotational speed of the main shaft is configured to be 20,000~40,000 rpm; the high-speed pulverizer performs a preset number of operation cycles, each operation cycle being a continuous crushing operation lasting 20~40 seconds, and the preset number of cycles is 3~6.

[0016] The applicant's research revealed that by controlling parameters such as the spindle speed and number of cycles in a high-speed pulverizer, the fracture mode of glass fibers can be influenced, thereby achieving targeted control over the proportion of long, medium, and short glass fibers. When the target composite powder needs to retain more long fibers, a lower rotation speed (e.g., 20,000-25,000 rpm) and fewer cycles (e.g., 3 times) are used to retain more long glass fibers in the composite powder. When the target composite powder needs to retain more short fibers, a higher rotation speed (e.g., 35,000-40,000 rpm) and more cycles (e.g., 5-6 times) are used to apply stronger impact and shear forces, causing the fibers to break multiple times, thereby increasing the yield of short fibers and powder.

[0017] Optionally, the high-speed pulverizer further includes a pulverizing chamber for holding intermediate materials. During the fine crushing, the pulverizing chamber is cooled by air cooling or water cooling so that the material temperature in the pulverizing chamber is ≤60℃.

[0018] Cooling the grinding chamber using air or water cooling ensures the material temperature remains below 60℃, preventing the thermosetting glass fiber composite material from softening due to friction and sticking to the cutting tools, thus significantly reducing tool wear. Furthermore, temperature control helps maintain the integrity of the glass fibers, preventing excessive fiber breakage and uneven distribution caused by overheating. This results in recycled powder with uniform particle size and stable quality, laying the structural foundation for the subsequent development of new metering boxes.

[0019] Optionally, after step S3, the method further includes: S4, activating the recycled powder obtained from each stage of the screen.

[0020] Activation treatment can compensate for the performance loss of waste box powder due to aging and further optimize the performance of glass fiber composite materials, ensuring that the subsequently produced composite metering boxes have sufficient mechanical strength, electrical properties and durability.

[0021] Optionally, the activation treatment includes: mixing the regenerated powder with an activator at 40~90°C, wherein the activator is selected from at least one of the following: triethanolamine, dimethylethanolamine, dimethylcyclohexylamine, triethylamine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, N,N-dimethylcyclohexylamine, hexadecyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, and benzyltriethylammonium chloride.

[0022] A temperature range of 40~90℃ promotes the diffusion of activator molecules and their interaction with the surface of recycled powder, ensuring good activation effect. In industrial production, a heated mixing tank with stirring can be used to mix the recycled powder and activator evenly. Amine compounds such as triethanolamine and dimethylcyclohexylamine, as well as quaternary ammonium salts such as hexadecyltrimethylammonium bromide and benzyltrimethylammonium hydroxide, all contain strongly polar functional groups (such as amino and quaternary ammonium ions). These strongly polar functional groups can undergo physical adsorption or chemical reaction with hydroxyl and carboxyl groups on the surface of powders made from aged glass fiber composites, thereby improving the chemical polarity, wettability, and reactivity of the powder surface and repairing the partially deactivated surface state due to aging. In addition, the functional groups in the activator can also react or form strong interactions with subsequently added resins (such as unsaturated polyester resins and epoxy resins) during hot pressing and curing, enhancing the interfacial adhesion strength between the powder and the newly added resin. Furthermore, plasma treatment can also be used to activate the powder surface.

[0023] Optionally, after step S4, step S5 is further included: drying the regenerated powder that has undergone the activation treatment, wherein the drying treatment is carried out by hot air drying and / or vacuum drying, the drying temperature is 60~110℃, and the drying endpoint is that the moisture content of the regenerated powder does not exceed 0.5%.

[0024] The drying process, which involves controlling the temperature between 60 and 110°C and using a combination of hot air and vacuum, removes the moisture and volatiles adsorbed during the activation process of the recycled powder. This ultimately controls the moisture content to no more than 0.5%, eliminating the potential for moisture to cause bubbles, weaken interfaces, and interfere with curing in subsequent composite material processing. Furthermore, by setting a specific drying endpoint, the performance stability and batch uniformity of the powder are ensured.

[0025] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. The preferred embodiments or means of the present invention will be shown in detail in conjunction with the accompanying drawings, but are not intended to limit the technical solutions of the present invention. In addition, each of these features, elements and components appearing in the following text and drawings is a plurality of, and different symbols or numbers are used for convenience of representation, but all represent parts with the same or similar construction or function. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described are intended to explain the present invention and should not be construed as limiting the invention.

[0028] The terms "an embodiment," "example," or "trademark" used in this specification refer to a particular feature, structure, or characteristic described in connection with the embodiment itself that may be included in at least one embodiment disclosed in this patent. The phrase "in an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0029] Example: like Figure 1 As shown, this embodiment provides a method for separating and recycling waste composite material metering boxes, including the following steps: S1. Metering box for recycling waste composite materials; S2. The waste composite material metering box is subjected to multi-stage crushing using a differential desorption process with impact-shear coupling to induce interfacial deadhesion and obtain composite powder containing resin powder, filler and glass fiber of different lengths. S3. The composite powder is sieved through a pre-set multi-stage screen to obtain the recycled powder retained on each stage of the screen. Along the direction of travel of the composite powder, the aperture of the multi-stage screen gradually decreases from the first stage to the last stage. Specifically, the length distribution of glass fibers in the composite powder is adjusted by regulating the process parameters of multi-stage crushing in step S2, and the content of glass fibers in the recycled powder obtained on each stage of the screen is adjusted by regulating the aperture of each stage of the screen.

[0030] In this embodiment, the waste composite material metering box refers to a discarded box whose performance has severely degraded due to physical and chemical aging caused by reaching or exceeding its design service life, making it unable to meet the original metering, protection, or structural strength requirements, and thus being replaced or phased out. The composite material can be glass fiber reinforced unsaturated polyester resin or glass fiber reinforced epoxy resin. The applicant discovered that the resin and fillers in the waste composite material are easier to crush than glass fibers. Brittle thermosetting resins and fillers are easily pulverized into fine powder under high-speed impact, while tough glass fibers are mainly cut rather than completely pulverized. The fracture length can be actively controlled by adjusting the multi-stage crushing process parameters, that is, by adjusting the process parameters, different composite powders with long glass fibers as the main component or short glass fibers as the main component can be produced preferentially. This solves the problem of random and uncontrollable glass fiber length distribution in the powder produced by the crushing process in the prior art, transforming the crushing process from uncontrollable to controllable and designable process steps. Specifically, the process parameters can include the selection of crushing equipment, the power of the crushing equipment, the crushing time, and the number of cycles in the crushing process. Furthermore, by setting up multi-stage sieves with progressively smaller apertures from the first to the last stage, it is possible not only to classify the composite powder according to particle size, but also to precisely control the content of glass fibers intercepted by each sieve stage based on the different lengths of glass fibers generated by the aforementioned multi-stage crushing. Fine resin and filler powders easily pass through each stage of the sieves, while glass fibers longer than the sieve aperture are easily trapped on the corresponding sieves. By adjusting the aperture of each stage of the sieves, the content of glass fibers in the recycled powder trapped on each stage can be controlled. That is, the large-aperture sieve traps long fibers, resulting in high-fiber powder, while the small-aperture sieve mainly collects fine powder and short fibers that pass through the large-aperture sieve, resulting in low-fiber powder. Ultimately, this achieves directional classification of the composite powder, and the content of the recovered powder components is controllable, thus resulting in stable performance and high application value.

[0031] Long glass fibers enhance the mechanical properties of materials (such as strength, toughness, and impact resistance), providing structural support. Short glass fibers, on the other hand, can improve the flowability or dimensional stability of materials. When long glass fibers are needed, the process parameters in the multi-stage crushing process are first adjusted to preferentially produce composite powder dominated by long glass fibers. In step S3, the aperture of the upper screen (such as the first and second stage screens) is set large enough so that the majority of the powder retained in the upper screen is long glass fibers. When short glass fibers are needed, the process parameters in the multi-stage crushing process are first adjusted to moderately reduce the aperture of the upper screen (such as the first stage) to intercept a small amount of uncrushed clumps or extremely long fibers. Simultaneously, the aperture combination of the middle and lower screens (such as the third to seventh stages) is adjusted to separate different particle size grades of subdivided products from the material mainly composed of short fibers and powder. For example, a coarser screen can trap slightly longer short fibers, resulting in filler with a higher fiber content; while the finest screen and chassis mainly collect fine powder of resin and filler, thereby achieving fine separation of short fibers from resin and filler.

[0032] Furthermore, the applicant's research revealed that completely separating resin powder and glass fiber is quite difficult. Therefore, this application does not simply involve crushing and screening, but rather links the crushing and screening processes into a controllable system. This allows for the selection of raw material components to produce recycled powder as needed, which is then used to manufacture a new composite material metering box for recycling.

[0033] The multi-stage screens include a first vibrating screen, a second vibrating screen, a third vibrating screen, a fourth vibrating screen, a fifth vibrating screen, a sixth vibrating screen, and a seventh vibrating screen arranged in sequence. The composite powder passes through the first vibrating screen to the seventh vibrating screen in sequence.

[0034] In this embodiment, the sequential arrangement of the first, second, third, fourth, fifth, sixth, and seventh vibrating screens ensures that the material passes through multiple screens in sequence, avoiding material blockage or backflow. Each screening stage further purifies or classifies the product from the previous stage, providing greater stability than single screening and facilitating automated continuous production. Furthermore, the screen body of the vibrating screen can vibrate at high frequency, resulting in high screening efficiency.

[0035] The first vibrating screen has a mesh size of 20, the second vibrating screen has a mesh size of 60, the third vibrating screen has a mesh size of 100, the fourth vibrating screen has a mesh size of 150, the fifth vibrating screen has a mesh size of 200, the sixth vibrating screen has a mesh size of 250, and the seventh vibrating screen has a mesh size of 300.

[0036] In this embodiment, the seven-stage sieve system, ranging from 20 to 300 mesh, forms a continuous sorting channel, enabling the step-by-step separation of a mixture containing glass fibers of varying lengths, resin powder, and filler powder that has undergone initial crushing. The upper coarse-mesh sieve preferentially traps long glass fibers that provide material reinforcement; the middle sieve separates intermediate products with varying ratios of long glass fibers to resin; and the lower fine-mesh sieve primarily collects resin powder. Through this specific sieving sequence, the composite powder is separated into recycled powders with different particle sizes and compositions.

[0037] In step S2, the intermittent impact multi-stage crushing includes pre-crushing, coarse crushing and fine crushing performed sequentially. After pre-crushing, the waste composite material metering box forms sheet-like or block-like materials with a length and width of 30-120 mm. After coarse crushing, the sheet-like or block-like materials form intermediate materials with a particle size of 10-40 mm. After fine crushing, the intermediate materials form composite powder with a particle size of 2-10 mm.

[0038] In this embodiment, the multi-stage crushing process employs a series of pre-crushing, coarse crushing, and fine crushing processes to achieve progressive crushing of waste composite material metering boxes. Specifically, pre-crushing first processes the complete box body into sheet-like or block-like materials of 30-120 mm, solving the problem of its irregular structure and difficulty in direct crushing; then coarse crushing reduces the particle size of the sheet-like or block-like materials to 10-40 mm; finally, fine crushing refines the material to 2-10 mm, forming composite powder. This effectively avoids the problems of equipment jamming or uneven crushing caused by direct single-equipment crushing in the prior art, ensuring crushing efficiency and product quality.

[0039] Pre-crushing includes: using cutting equipment to slot and cut the waste composite metering box to form sheet or block materials; coarse crushing includes: using a twin-shaft shredder, shear crusher or hammer crusher to crush the sheet or block materials to form intermediate materials.

[0040] In this embodiment, the waste metering box is large and complex in structure. Pre-crushing involves directional grooving and cutting to break it down into flake / block materials, reducing the pressure on subsequent crushing equipment. Directly crushing large, high-strength metering boxes would cause severe impact and wear on the crushing equipment blades. Distributing the crushing process across three stages of equipment reduces blade wear on each stage. Furthermore, the intermediate material obtained after coarse crushing provides a suitable feed size for subsequent fine crushing equipment.

[0041] Fine crushing includes: using a high-speed crusher to crush intermediate materials into composite powder. The high-speed crusher includes a main shaft and blades fixed to the main shaft. The rotation speed of the main shaft is configured to be 20,000~40,000 rpm. The high-speed crusher performs a preset number of operation cycles. Each operation cycle is a continuous crushing operation with a duration of 20 to 40 seconds. The preset number of cycles is 3 to 6.

[0042] In this embodiment, the applicant discovered through research that by controlling parameters such as the spindle speed and the number of operation cycles of a high-speed pulverizer, the fracture mode of glass fibers can be affected, thereby achieving directional control over the proportion of glass fibers of different lengths (long, medium, and short). When the target composite powder needs to retain more long fibers, a lower rotation speed (e.g., 20,000-25,000 rpm) and fewer operation cycles (e.g., 3 times) are used to retain more long glass fibers in the composite powder. When the target composite powder needs to retain more short fibers, a higher rotation speed setting (e.g., 35,000-40,000 rpm) and more operation cycles (e.g., 5-6 times) are used to apply stronger impact and shear forces, causing the fibers to break multiple times, thereby increasing the yield of short fibers and powder.

[0043] The high-speed crusher also includes a crushing chamber for holding intermediate materials. During fine crushing, the crushing chamber is cooled by air cooling or water cooling to keep the material temperature in the crushing chamber ≤60℃.

[0044] In this embodiment, the grinding chamber is cooled by air or water to keep the material temperature ≤60℃. This prevents the thermosetting glass fiber composite material from softening due to friction and sticking to the cutting tools, thus significantly reducing tool wear. Furthermore, temperature control helps maintain the integrity of the glass fibers, preventing excessive fiber breakage and uneven distribution caused by overheating. This ultimately yields recycled powder with uniform particle size and stable quality, laying the structural foundation for the subsequent fabrication of a new metering box.

[0045] The process after step S3 includes: S4, activating the recycled powder obtained from each stage of the screen.

[0046] In this embodiment, the activation treatment can compensate for the performance loss of the waste box powder due to aging and further optimize the performance of the glass fiber composite material, ensuring that the subsequently produced composite material metering box has sufficient mechanical strength, electrical performance and durability.

[0047] The activation treatment includes mixing the regenerated powder with an activator at 40~90℃. The activator is selected from at least one of the following: triethanolamine, dimethylethanolamine, dimethylcyclohexylamine, triethylamine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, N,N-dimethylcyclohexylamine, hexadecyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, and benzyltriethylammonium chloride.

[0048] In this embodiment, a temperature range of 40-90°C promotes the diffusion of activator molecules and their interaction with the surface of the recycled powder, ensuring a good activation effect. In industrial production, a heated mixing tank with stirring can be used to mix the recycled powder and activator evenly. Amine compounds such as triethanolamine and dimethylcyclohexylamine, as well as quaternary ammonium salts such as hexadecyltrimethylammonium bromide and benzyltrimethylammonium hydroxide, all contain strongly polar functional groups (such as amino and quaternary ammonium ions). These strongly polar functional groups can undergo physical adsorption or chemical reaction with hydroxyl and carboxyl groups present on the surface of powders made from aged glass fiber composites, thereby improving the chemical polarity, wettability, and reactivity of the powder surface and repairing the partially deactivated surface state due to aging. In addition, the functional groups in the activator can also react or form strong interactions with subsequently added resins (such as unsaturated polyester resins and epoxy resins) during hot-press curing, enhancing the interfacial bonding strength between the powder and the newly added resin. Furthermore, plasma treatment can also be used to activate the powder surface.

[0049] After step S4, step S5 is also included: drying the activated recycled powder, using hot air drying and / or vacuum drying, at a temperature of 60~110℃, and the drying endpoint is when the moisture content of the recycled powder does not exceed 0.5%.

[0050] In this embodiment, the drying process involves controlling the temperature between 60 and 110°C and using a combination of hot air and vacuum to remove the moisture and volatiles adsorbed by the recycled powder during activation. This ultimately controls the moisture content to no more than 0.5%, eliminating the potential for moisture to cause bubbles, weaken interfaces, and interfere with curing during subsequent composite material processing. Furthermore, by setting a specific drying endpoint, the performance stability and batch uniformity of the powder are ensured.

[0051] Preparation Example 1: In this preparation example, a high-speed pulverizer with a spindle speed of 39,000 rpm was used, with 5 operation cycles and each cycle lasting 20 seconds, to finely crush the intermediate material. Subsequently, a screening machine with seven levels of vibrating screens (mesh sizes from the first to the seventh level being 20 mesh, 60 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh, and 300 mesh, respectively) was used to screen the crushed composite powder. The resin content in the recycled powder retained on the 60-mesh vibrating screen was 78.86%.

[0052] Preparation Example 2: In this preparation example, a high-speed pulverizer with a spindle speed of 35,000 rpm was used, with 6 operating cycles and each cycle lasting 20 seconds, to finely crush the intermediate material. Screening was performed using a seven-stage vibrating screen (with mesh sizes of 20, 60, 100, 150, 200, 250, and 300 mesh from the first to the seventh stage). The resin content in the recycled powder retained on the 60-mesh vibrating screen was 71.35%.

[0053] Preparation Example 3: In this preparation example, the waste composite material metering box was first pre-crushed: it was cut into sheet or block materials with a length and width of 30-120 mm using a toothed saw blade cutting device. Then, a twin-shaft shredder was used to coarsely crush the sheet or block material, obtaining intermediate material with a particle size of 10-40 mm. Next, a high-speed pulverizer (spindle speed 39000 rpm) was used to finely crush the intermediate material, setting the operation cycle to 12 times, with each cycle lasting 20 seconds, to obtain composite powder with a particle size of 2-10 mm. The composite powder was then screened using a sieving system with seven levels of vibrating screens (mesh sizes of 20, 60, 100, 150, 200, 250, and 300 mesh). The resin content in the recycled powder retained on the 60-mesh screen was 79.14%.

[0054] Preparation Example 4: In this preparation example, the waste composite material metering box was first pre-crushed using a toothed saw blade cutting device to process it into sheet-like or block-like materials with a length and width of 30-120 mm. Subsequently, a hammer crusher was used for primary coarse crushing to obtain intermediate material with a particle size of 10-40 mm. Next, a shear crusher was used for fine crushing of the intermediate material to obtain composite powder with a particle size of 2-10 mm, while simultaneously removing any metallic impurities. This composite powder was then fed into a high-speed pulverizer with a spindle speed of 35,000 rpm, with 15 cycles per 20 seconds for final pulverization. The resulting powder was then sieved using a seven-stage vibrating screen (mesh sizes of 20, 60, 100, 150, 200, 250, and 300 mesh). The resin content in the recycled powder retained on the 60-mesh screen was 80.75%.

[0055] Comparing Preparation Examples 1 to 4, it can be seen that by implementing the multi-stage crushing and multi-stage sieving method of the present invention, powder with a resin content higher than 70% (material passing through a 60-mesh sieve) can be stably obtained, which also demonstrates that the method can effectively separate resin and glass fiber. Furthermore, by changing the combination of the crushing speed and the number of cycles in different preparation examples, different resin content results were obtained, confirming that the component distribution of the final product can be actively influenced by adjusting process parameters.

[0056] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A method for separating and recycling waste composite material metering boxes, characterized in that, Includes the following steps: S1. Metering box for recycling waste composite materials; S2. The waste composite material metering box is crushed in multiple stages to obtain composite powder containing resin powder, filler and glass fiber of different lengths. S3. The composite powder is sieved through a preset multi-stage sieve to obtain the recycled powder retained on each sieve. The aperture of the multi-stage sieve gradually decreases from the first stage to the last stage along the direction of travel of the composite powder. Specifically, the length distribution of glass fibers in the composite powder is adjusted by regulating the process parameters of multi-stage crushing in step S2, and the content of glass fibers in the recycled powder obtained on each stage of the screen is adjusted by regulating the aperture of each stage of the screen.

2. The method for separating and recycling waste composite material metering boxes according to claim 1, characterized in that, In step S3, the multi-stage screens include a first vibrating screen, a second vibrating screen, a third vibrating screen, a fourth vibrating screen, a fifth vibrating screen, a sixth vibrating screen, and a seventh vibrating screen arranged in sequence, and the composite powder passes through the first vibrating screen to the seventh vibrating screen in sequence.

3. The method for separating and recycling waste composite material metering boxes according to claim 2, characterized in that, The first vibrating screen has a mesh size of 20, the second vibrating screen has a mesh size of 60, the third vibrating screen has a mesh size of 100, the fourth vibrating screen has a mesh size of 150, the fifth vibrating screen has a mesh size of 200, the sixth vibrating screen has a mesh size of 250, and the seventh vibrating screen has a mesh size of 300.

4. The method for separating and recycling waste composite material metering boxes according to claim 1, characterized in that, In step S2, the multi-stage crushing includes pre-crushing, coarse crushing and fine crushing performed sequentially. After the pre-crushing, the waste composite material metering box forms sheet-like or block-like materials with a length and width of 30-120 mm. After the coarse crushing, the sheet-like or block-like materials form intermediate materials with a particle size of 10-40 mm. After the fine crushing, the intermediate materials form composite powder with a particle size of 2-10 mm.

5. The method for separating and recycling waste composite material metering boxes according to claim 4, characterized in that, The pre-crushing includes: using cutting equipment to slot and cut the waste composite metering box to form sheet-like or block-like materials; the coarse crushing includes: using a twin-shaft shredder, shear crusher or hammer crusher to crush the sheet-like or block-like materials to form intermediate materials.

6. The method for separating and recycling waste composite material metering boxes according to claim 4, characterized in that, The fine crushing includes: using a high-speed crusher to crush intermediate materials into composite powder. The high-speed crusher includes a main shaft and blades fixed to the main shaft. The rotation speed of the main shaft is configured to be 20,000 to 40,000 rpm. The high-speed crusher performs a preset number of operation cycles, each operation cycle being a continuous crushing operation lasting 20 to 40 seconds, and the preset number of cycles is 3 to 6.

7. The method for separating and recycling waste composite material metering boxes according to claim 6, characterized in that, The high-speed crusher also includes a crushing chamber for holding intermediate materials. During the fine crushing, the crushing chamber is cooled by air cooling or water cooling so that the material temperature in the crushing chamber is ≤60℃.

8. The method for separating and recycling waste composite material metering boxes according to any one of claims 1-7, characterized in that, The process after step S3 includes: S4, activating the recycled powder obtained from each stage of the screen.

9. The method for separating and recycling waste composite material metering boxes according to claim 8, characterized in that, The activation treatment includes mixing the regenerated powder with an activator at 40~90°C. The activator is selected from at least one of the following: triethanolamine, dimethylethanolamine, dimethylcyclohexylamine, triethylamine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, N,N-dimethylcyclohexylamine, hexadecyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, and benzyltriethylammonium chloride.

10. The method for separating and recycling waste composite material metering boxes according to claim 8, characterized in that, After step S4, step S5 is also included: drying the regenerated powder that has undergone the activation treatment, wherein the drying treatment is carried out by hot air drying and / or vacuum drying, the drying temperature is 60~110℃, and the drying endpoint is that the moisture content of the regenerated powder does not exceed 0.5%.

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