A graphite tailings / polyethylene composite material and its preparation method

Abstract

A graphite tailings / polyethylene composite material and a preparation method thereof, belonging to the technical field of polyethylene composite material preparation. To provide a graphite tailings / polyethylene composite material with excellent mechanical properties, the present invention performs reduced pressure drying of 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid in a flask, adds N,N-dimethylformamide and N,N-diisopropylethylamine for reaction, filters and washes after the reaction, and vacuum dries to obtain hydroxylated formyl uracil; lactide, stannous octoate, N,N-dimethylformamide and hydroxylated formyl uracil are added to a flask for reaction under nitrogen protection, and washed and vacuum dried after the reaction to obtain uracil-terminated polylactide interfacial compatibilizer; graphite tailings powder, polyethylene resin particles and uracil-terminated polylactide interfacial compatibilizer are uniformly mixed, extruded in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of polyethylene composite material preparation, and particularly relates to a graphite tailings / polyethylene composite material and a preparation method thereof. Background Art

[0002] The impact of mineral solid waste on the environment is a slow and long-term process, and its impact will become greater and greater over time. For a long time, the treatment of mineral solid waste has not received enough attention, resulting in the relatively lagging development of mineral solid waste treatment in various sub-industries in the field of environmental protection. The treatment and comprehensive utilization of mine tailings has always been an international issue and is listed as the main pollution problem in the treatment and reuse of construction waste. As an important strategic resource, graphite is mainly distributed in China, India, Brazil and other countries, among which my country is the world's largest graphite producer. At present, flotation is mainly used to screen and purify graphite deposits, but each ton of graphite purified by this method will produce about 10-15 tons of graphite tailings. The large accumulation of graphite tailings has encroached on farmland, reduced land utilization, and caused environmental degradation and soil erosion around mines. Moreover, the small particle size of graphite tailings is prone to cause sand blowing, which seriously damages the ecological environment. The hazards of graphite tailings are being recognized, and the application of graphite tailings in environmental protection treatment and understanding methods is becoming a research focus. So far, the application scope of graphite tailings is relatively narrow, mostly used in landfills of roadbed foundations. The advanced utilization of graphite tailings is mainly focused on the extraction of heavy metals and the preparation of foamed concrete. Graphite tailings have not been effectively utilized.

[0003] Polyethylene is a non-polar thermoplastic material. It is widely used in applications such as packaging, furniture and agricultural films due to its good processing properties, acceptable strength, excellent chemical resistance and relatively low cost. However, the heat resistance of polyethylene is relatively poor and it is easily softened and deformed by high temperature. In addition, the mechanical properties are unstable and may change under different temperatures and humidity, and the stability is poor. In order to improve the heat resistance and mechanical properties of polyethylene, graphite tailings can be used as an inorganic filler to prepare graphite tailings / polyethylene composites. However, the two have significant differences in polarity, and simple extrusion molding will affect the mechanical properties of the composite material, so it is necessary to enhance the interface compatibility of the composite material. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a graphite tailings / polyethylene composite material with excellent mechanical properties, and propose a graphite tailings / polyethylene composite material and a preparation method thereof.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0007] S1. 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid are dried under reduced pressure in a flask, and then N,N-dimethylformamide and N,N-diisopropylethylamine are added to react. After the reaction is completed, the collected solid product is filtered and repeatedly washed with methanol, and then vacuum dried to obtain hydroxylated formyl uracil for standby use;

[0008] S2. lactide, stannous octoate, N,N-dimethylformamide and the hydroxylated formyl uracil obtained in step S1 are added to a flask and reacted under nitrogen protection. After the reaction, the precipitate is washed in ether, and the precipitate is vacuum dried to obtain a uracil-terminated polylactide interfacial compatibilizer for standby use;

[0009] S3. The graphite tailings powder, polyethylene resin particles and the uracil-terminated polylactide interfacial compatibilizer obtained in step S2 are mixed uniformly in a high-speed homogenizer to obtain a mixture for standby use;

[0010] S4. Extruding the mixture obtained in step S3 in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

[0011] Furthermore, the amount of each material added in step S1 is calculated by weight: 2 to 50 parts of 5-formyluracil, 5 to 80 parts of 5-amino-1-pentanol, 5 to 80 parts of benzotriazoletetramethyltetrafluoroboric acid, 20 to 400 parts of N,N-dimethylformamide, and 4 to 80 parts of N,N-diisopropylethylamine; the drying time of the reduced pressure drying is 6 to 8 hours, the drying conditions are at room temperature, and the pressure is ≤1000 Pa; the reaction temperature of the reaction is 40 to 50° C., and the reaction time is 12 to 24 hours.

[0012] Furthermore, the amount of each material added in step S2 is calculated by weight: 1 to 40 parts of hydroxylated formyl uracil, 6 to 100 parts of lactide, 1 to 3 parts of stannous octoate, 15 to 200 parts of N,N-dimethylformamide, and 50 to 5000 parts of ether; the reaction temperature is 110 to 130° C., and the reaction time is 6 to 12 hours.

[0013] Furthermore, in step S1 and step S2, the vacuum drying temperature is 50 to 80° C., and the vacuum drying time is 8 to 24 hours.

[0014] Furthermore, the added amount of each material in step S3 is calculated by weight: 10 to 800 parts of graphite tailings powder, 10 to 1000 parts of polyethylene resin particles, and 1 to 100 parts of uracil-terminated polylactide interfacial compatibilizer; the mixing time is 10 to 30 minutes.

[0015] Furthermore, during the twin-screw extrusion process in step S4, the temperatures of various regions from the discharge port to the feed port are set to 115° C., 145° C., 155° C., 155° C., and 115° C., and the rotation speed of the twin-screw extrusion is 2 to 5 rad / s.

[0016] A graphite tailings / polyethylene composite material is realized by relying on the preparation method of the graphite tailings / polyethylene composite material. The maximum flexural strength of the graphite tailings / polyethylene composite material reaches 42.28MPa.

[0017] Beneficial effects of the present invention:

[0018] The preparation method of a graphite tailings / polyethylene composite material of the present invention uses uracil-terminated polylactide as an interfacial compatibilizer to enhance the graphite tailings / polyethylene composite material. The end of the molecular chain of the interfacial compatibilizer has a polar group, which is similar to the polarity of the surface of the graphite tailings, and polylactide belongs to a weakly polar polymer chain, which is similar to the polarity of polyethylene, and the polylactide molecular chain can form a physical entanglement with the polyethylene molecular chain during the extrusion process to further improve the compatibility. This allows the uracil-terminated polylactide interfacial compatibilizer to tightly connect the graphite tailings and polyethylene together as a molecular chain, thereby achieving the graphite tailings / polyethylene composite material enhancement effect.

[0019] The method for preparing a graphite tailings / polyethylene composite material of the present invention has a simple process, low energy consumption and high production efficiency, and is a simple and efficient method for preparing a graphite tailings / polyethylene composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A real photo of a graphite tailings / polyethylene composite material prepared by the present invention;

[0021] Figure 2 This is a real photo of a graphite tailings / polyethylene composite material prepared by the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0023] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0024] In order to further understand the content, features and effects of the present invention, the following specific implementation methods are given as examples, and the attached Figure 1 -Attached Figure 2 The detailed instructions are as follows:

[0025] Embodiment 1:

[0026] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0027] S1. 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid are dried under reduced pressure in a flask, and then N,N-dimethylformamide and N,N-diisopropylethylamine are added to react. After the reaction is completed, the collected solid product is filtered and repeatedly washed with methanol, and then vacuum dried to obtain hydroxylated formyl uracil for standby use;

[0028] Furthermore, the amount of each material added in step S1 is calculated by weight: 13 parts of 5-formyluracil, 20 parts of 5-amino-1-pentanol, 20 parts of benzotriazole tetramethyl tetrafluoroboric acid, 120 parts of N,N-dimethylformamide, and 12 parts of N,N-diisopropylethylamine; the drying time of the reduced pressure drying is 6 hours, the drying conditions are room temperature, and the pressure is 1000 Pa; the reaction temperature of the reaction is 50° C., and the reaction time is 16 hours;

[0029] S2. lactide, stannous octoate, N,N-dimethylformamide and the hydroxylated formyl uracil obtained in step S1 are added to a flask and reacted under nitrogen protection. After the reaction, the precipitate is washed in ether, and the precipitate is vacuum dried to obtain a uracil-terminated polylactide interfacial compatibilizer for standby use;

[0030] Furthermore, the amount of each material added in step S2 is calculated by weight: 22 parts of hydroxylated formyl uracil, 50 parts of lactide, 1 part of stannous octoate, 100 parts of N,N-dimethylformamide, and 500 parts of ether; the reaction temperature is 110° C., and the reaction time is 12 hours;

[0031] Furthermore, in step S1 and step S2, the vacuum drying temperature is 60° C., and the vacuum drying time is 12 h;

[0032] S3. The graphite tailings powder, polyethylene resin particles and the uracil-terminated polylactide interfacial compatibilizer obtained in step S2 are mixed uniformly in a high-speed homogenizer to obtain a mixture for standby use;

[0033] Furthermore, the addition amount of each material in step S3 is calculated by weight: 600 parts of graphite tailings powder, 400 parts of polyethylene resin particles, and 10 parts of uracil-terminated polylactide interfacial compatibilizer; the mixing time is 30 minutes;

[0034] S4. Extruding the mixture obtained in step S3 in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

[0035] Furthermore, during the twin-screw extrusion process in step S4, the temperatures of various regions from the discharge port to the feed port are set to 115° C., 145° C., 155° C., 155° C., and 115° C., and the rotation speed of the twin-screw extrusion is 4 rad / s.

[0036] Embodiment 2:

[0037] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0038] S1. 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid are dried under reduced pressure in a flask, and then N,N-dimethylformamide and N,N-diisopropylethylamine are added to react. After the reaction is completed, the collected solid product is filtered and repeatedly washed with methanol, and then vacuum dried to obtain hydroxylated formyl uracil for standby use;

[0039] Furthermore, the amount of each material added in step S1 is calculated by weight: 10 parts of 5-formyluracil, 25 parts of 5-amino-1-pentanol, 25 parts of benzotriazole tetramethyl tetrafluoroboric acid, 120 parts of N,N-dimethylformamide, and 12 parts of N,N-diisopropylethylamine; the drying time of the reduced pressure drying is 6 hours, the drying conditions are room temperature, and the pressure is 1000 Pa; the reaction temperature of the reaction is 50° C., and the reaction time is 16 hours;

[0040] S2. lactide, stannous octoate, N,N-dimethylformamide and the hydroxylated formyl uracil obtained in step S1 are added to a flask and reacted under nitrogen protection. After the reaction, the precipitate is washed in ether, and the precipitate is vacuum dried to obtain a uracil-terminated polylactide interfacial compatibilizer for standby use;

[0041] Furthermore, the amount of each material added in step S2 is calculated by weight: 20 parts of hydroxyformyl uracil, 70 parts of lactide, 1 part of stannous octoate, 120 parts of N,N-dimethylformamide, and 600 parts of ether; the reaction temperature is 110° C., and the reaction time is 12 hours;

[0042] Furthermore, in step S1 and step S2, the vacuum drying temperature is 60° C., and the vacuum drying time is 12 h;

[0043] S3. The graphite tailings powder, polyethylene resin particles and the uracil-terminated polylactide interfacial compatibilizer obtained in step S2 are mixed uniformly in a high-speed homogenizer to obtain a mixture for standby use;

[0044] Furthermore, the addition amount of each material in step S3 is calculated by weight: 600 parts of graphite tailings powder, 400 parts of polyethylene resin particles, and 30 parts of uracil-terminated polylactide interfacial compatibilizer; the mixing time is 30 minutes;

[0045] S4. Extruding the mixture obtained in step S3 in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

[0046] Furthermore, during the twin-screw extrusion process in step S4, the temperatures of various regions from the discharge port to the feed port are set to 115° C., 145° C., 155° C., 155° C., and 115° C., and the rotation speed of the twin-screw extrusion is 4 rad / s.

[0047] Embodiment 3:

[0048] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0049] S1. 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid are dried under reduced pressure in a flask, and then N,N-dimethylformamide and N,N-diisopropylethylamine are added to react. After the reaction is completed, the collected solid product is filtered and repeatedly washed with methanol, and then vacuum dried to obtain hydroxylated formyl uracil for standby use;

[0050] Furthermore, the amount of each material added in step S1 is calculated by weight: 16 parts of 5-formyluracil, 20 parts of 5-amino-1-pentanol, 25 parts of benzotriazole tetramethyl tetrafluoroboric acid, 120 parts of N,N-dimethylformamide, and 12 parts of N,N-diisopropylethylamine; the drying time of the reduced pressure drying is 6 hours, the drying conditions are room temperature and the pressure is 800 Pa; the reaction temperature of the reaction is 50° C., and the reaction time is 16 hours;

[0051] S2. lactide, stannous octoate, N,N-dimethylformamide and the hydroxylated formyl uracil obtained in step S1 are added to a flask and reacted under nitrogen protection. After the reaction, the precipitate is washed in ether, and the precipitate is vacuum dried to obtain a uracil-terminated polylactide interfacial compatibilizer for standby use;

[0052] Furthermore, the amount of each material added in step S2 is calculated by weight: 20 parts of hydroxylated formyl uracil, 55 parts of lactide, 1 part of stannous octoate, 120 parts of N,N-dimethylformamide, and 500 parts of ether; the reaction temperature is 110° C., and the reaction time is 12 hours;

[0053] Furthermore, in step S1 and step S2, the vacuum drying temperature is 60° C., and the vacuum drying time is 12 h;

[0054] S3. The graphite tailings powder, polyethylene resin particles and the uracil-terminated polylactide interfacial compatibilizer obtained in step S2 are mixed uniformly in a high-speed homogenizer to obtain a mixture for standby use;

[0055] Furthermore, the addition amount of each material in step S3 is calculated by weight: 600 parts of graphite tailings powder, 400 parts of polyethylene resin particles, and 50 parts of uracil-terminated polylactide interfacial compatibilizer; the mixing time is 30 minutes;

[0056] S4. Extruding the mixture obtained in step S3 in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

[0057] Furthermore, during the twin-screw extrusion process in step S4, the temperatures of various regions from the discharge port to the feed port are set to 115° C., 145° C., 155° C., 155° C., and 115° C., and the rotation speed of the twin-screw extrusion is 2 to 5 rad / s.

[0058] Embodiment 4:

[0059] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0060] S1. 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid are dried under reduced pressure in a flask, and then N,N-dimethylformamide and N,N-diisopropylethylamine are added to react. After the reaction is completed, the collected solid product is filtered and repeatedly washed with methanol, and then vacuum dried to obtain hydroxylated formyl uracil for standby use;

[0061] Furthermore, the amount of each material added in step S1 is calculated by weight: 15 parts of 5-formyluracil, 25 parts of 5-amino-1-pentanol, 25 parts of benzotriazole tetramethyl tetrafluoroboric acid, 120 parts of N,N-dimethylformamide, and 12 parts of N,N-diisopropylethylamine; the drying time of the reduced pressure drying is 6 hours, the drying conditions are room temperature and the pressure is 1000 Pa; the reaction temperature of the reaction is 50° C., and the reaction time is 16 hours;

[0062] S2. lactide, stannous octoate, N,N-dimethylformamide and the hydroxylated formyl uracil obtained in step S1 are added to a flask and reacted under nitrogen protection. After the reaction, the precipitate is washed in ether, and the precipitate is vacuum dried to obtain a uracil-terminated polylactide interfacial compatibilizer for standby use;

[0063] Furthermore, the amount of each material added in step S2 is calculated by weight: 22 parts of hydroxylated formyl uracil, 60 parts of lactide, 1 part of stannous octoate, 120 parts of N,N-dimethylformamide, and 600 parts of ether; the reaction temperature is 110° C., and the reaction time is 12 hours;

[0064] Furthermore, in step S1 and step S2, the vacuum drying temperature is 60° C., and the vacuum drying time is 12 h;

[0065] S3. The graphite tailings powder, polyethylene resin particles and the uracil-terminated polylactide interfacial compatibilizer obtained in step S2 are mixed uniformly in a high-speed homogenizer to obtain a mixture for standby use;

[0066] Furthermore, the addition amount of each material in step S3 is calculated by weight: 600 parts of graphite tailings powder, 400 parts of polyethylene resin particles, and 70 parts of uracil-terminated polylactide interfacial compatibilizer; the mixing time is 30 minutes;

[0067] S4. Extruding the mixture obtained in step S3 in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

[0068] Furthermore, during the twin-screw extrusion process in step S4, the temperatures of various regions from the discharge port to the feed port are set to 115° C., 145° C., 155° C., 155° C., and 115° C., and the rotation speed of the twin-screw extrusion is 2 to 5 rad / s.

[0069] Comparative Example 1:

[0070] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0071] (1) Raw Materials: 600 parts by mass of graphite tailings powder and 400 parts by mass of polyethylene resin particles were mixed in a high-speed homogenizer for 30 minutes.

[0072] (2) The uniformly mixed mixture is extruded in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material. During the extrusion process, the temperature of each area from the discharge port to the feed port is set to 115°C-145°C-155°C-155°C-115°C, and the rotation speed is 4rad / s.

[0073] Comparative Example 2:

[0074] A method for preparing a graphite tailings / polyethylene composite material comprises the following steps:

[0075] (1) Raw materials, by mass, 15 parts of 5-formyluracil, 25 parts of 5-amino-1-pentanol and 25 parts of benzotriazole tetramethyltetrafluoroboric acid were dried under reduced pressure in a flask for 6 hours, and then 120 parts of N,N-dimethylformamide and 12 parts of N,N-diisopropylethylamine were added and reacted at 50°C for 16 hours. After the reaction was completed, the solid was collected by filtration, repeatedly washed with methanol, and then vacuum dried at 60°C for 12 hours to obtain hydroxylated formyluracil.

[0076] (2) 600 parts of graphite tailings powder, 400 parts of polyethylene resin particles and 10 parts of hydroxylated formyl uracil were mixed in a high-speed homogenizer for 30 minutes.

[0077] (3) The uniformly mixed mixture is extruded into a twin-screw extruder to obtain a graphite tailings / polyethylene composite material. During the extrusion process, the temperature of each area from the discharge port to the feed port is set to 115°C-145°C-155°C-155°C-115°C, and the rotation speed is 4rad / s.

[0078] In order to detect the mechanical properties and toughness of the graphite tailings / polyethylene composite materials, the tensile strength, tensile elongation at break and impact strength of the graphite tailings / polyethylene composite materials of Examples 1-4 were investigated and compared with Comparative Examples 1 and 2. The results are shown in Table 1.

[0079] The bending strength of graphite tailings / polyethylene composite materials refers to the standard GB / T9341-2008 (determination of bending properties of plastics), the specimen size is 80mm×10mm×4mm, the support spacing is 64mm, and the pressure head descending speed is 2mm / min. The tensile strength and tensile elongation at break are tested in accordance with the standard GB / T 1040.1-2018 (determination of tensile properties of plastics), the specimen size is 75mm×5mm×2mm, the tensile speed is 2mm / min, and the fixture spacing is 58mm. The impact strength refers to the standard GB / T1043.1-2008 (determination of impact properties of simply supported beams of plastics), and the specimen size is 80mm×10mm×4mm. At least five samples are tested for each test, and the results are averaged. The specific performance is shown in Table 1 below.

[0080] Table 1 Performance parameters of graphite tailings / polyethylene composites

[0081]

[0082] As shown in the results of Table 1, it can be found that the mechanical properties and toughness of the graphite tailings / polyethylene composite material with the addition of uracil-terminated polylactide interfacial compatibilizer are stronger than those of the composite material without the addition of the auxiliary agent. This is because the uracil-terminated polylactide interfacial compatibilizer is a kind of amphiphilic macromolecular structure, the polarity of the uracil end group is close to the surface polarity of the graphite tailings filler, and the molecular chain in the middle is close to the polarity of polyethylene. Such a macromolecular structure can be used as a molecular chain to tightly connect the graphite tailings and polyethylene together, which can significantly improve the interfacial compatibility of the composite material. It can be found that the addition of hydroxylated formyl uracil alone cannot improve the mechanical properties and toughness of the composite material, because it cannot form an interfacial bridging effect, resulting in the inability to form a good interfacial layer to stabilize the internal structure of the composite material. It can be seen from the comparison of Examples 1-4 that different preparation process parameters have a direct impact on the mechanical properties and toughness of the composite material, wherein the performance of the composite material obtained under the conditions of Example 2 is better.

[0083] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0084] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a graphite tailings / polyethylene composite material, characterized in that: The steps include: S1. 5-formyl uracil, 5-amino-1-pentanol and benzotriazole tetramethyl tetrafluoroboric acid are dried under reduced pressure in a flask, and then N,N-dimethylformamide and N,N-diisopropylethylamine are added to react. After the reaction is completed, the collected solid product is filtered and repeatedly washed with methanol, and then vacuum dried to obtain hydroxylated formyl uracil for standby use; S2. lactide, stannous octoate, N,N-dimethylformamide and the hydroxylated formyl uracil obtained in step S1 are added to a flask and reacted under nitrogen protection. After the reaction, the precipitate is washed in ether, and the precipitate is vacuum dried to obtain a uracil-terminated polylactide interfacial compatibilizer for standby use; S3. The graphite tailings powder, polyethylene resin particles and the uracil-terminated polylactide interfacial compatibilizer obtained in step S2 are mixed uniformly in a high-speed homogenizer to obtain a mixture for standby use; S4. Extruding the mixture obtained in step S3 in a twin-screw extruder to obtain a graphite tailings / polyethylene composite material.

2. The method for preparing a graphite tailings / polyethylene composite material according to claim 1, wherein: The added amount of each material in step S1 is calculated by weight: 2 to 50 parts of 5-formyluracil, 5 to 80 parts of 5-amino-1-pentanol, 5 to 80 parts of benzotriazoletetramethyltetrafluoroboric acid, 20 to 400 parts of N,N-dimethylformamide, and 4 to 80 parts of N,N-diisopropylethylamine; the drying time of the reduced pressure drying is 6 to 8 hours, the drying conditions are at room temperature, and the pressure is ≤1000 Pa; the reaction temperature of the reaction is 40 to 50° C., and the reaction time is 12 to 24 hours.

3. The method for preparing a graphite tailings / polyethylene composite material according to claim 2, wherein: The amount of each material added in step S2 is calculated by weight: 1 to 40 parts of hydroxylated formyl uracil, 6 to 100 parts of lactide, 1 to 3 parts of stannous octoate, 15 to 200 parts of N,N-dimethylformamide, and 50 to 5000 parts of ether; the reaction temperature is 110 to 130° C., and the reaction time is 6 to 12 hours.

4. The method for preparing a graphite tailings / polyethylene composite material according to claim 2 or 3, characterized in that: In step S1 and step S2, the vacuum drying temperature is 50-80° C., and the vacuum drying time is 8-24 hours.

5. The method for preparing a graphite tailings / polyethylene composite material according to claim 4, characterized in that: The added amount of each material in step S3 is calculated by weight: 10 to 800 parts of graphite tailings powder, 10 to 1000 parts of polyethylene resin particles, and 1 to 100 parts of uracil-terminated polylactide interfacial compatibilizer; the mixing time is 10 to 30 minutes.

6. The method for preparing a graphite tailings / polyethylene composite material according to claim 5, characterized in that: During the twin-screw extrusion process in step S4, the temperatures of various regions from the discharge port to the feed port are set to 115° C., 145° C., 155° C., 155° C., and 115° C., and the rotation speed of the twin-screw extrusion is 2 to 5 rad / s.

7. A graphite tailings / polyethylene composite material, obtained by the preparation method of a graphite tailings / polyethylene composite material according to any one of claims 1 to 6, characterized in that: The maximum flexural strength of the graphite tailings / polyethylene composite material reaches 42.28 MPa.

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