Waste insulator core rod recovery system and method

Abstract

The embodiment of the invention provides a waste insulator core rod recycling system and method. The waste insulator core rod recycling system comprises a reaction container, electrodes and a power source. The reaction container is used for containing a premix containing a waste insulator core rod and a conductive material. The number of the electrodes is two, and the two electrodes are oppositely arranged in the reaction container and are configured to be in contact with the premix. The power supply is electrically connected with the electrode, forms a discharge path with the conductive material, and is configured to apply current to the electrode, so that the discharge path is short-circuited to generate heat. A reaction container for accommodating a waste insulator core rod and a conductive material is arranged, and current is applied to the reaction container. Through the high thermal effect of the resistor, high temperature is generated in the reaction container at the moment of current application, and silicon carbide can be synthesized in an extremely short time.

Description

Technical Field

[0001] This application relates to the technical field of waste material recycling, and particularly to a recycling system and method for waste insulator mandrels. Background Art

[0002] With the gradual retirement of composite insulators used in the power grid, how to achieve their efficient and environmentally friendly recycling has become a key problem to be solved urgently. The mandrel is one of the main components of the composite insulator, which is mainly composed of a glass fiber reinforced composite material based on epoxy resin, and its main component is silicon dioxide. In recent years, silicon dioxide has attracted attention due to its raw material status in the preparation of silicon carbide. As a semiconductor material, silicon carbide has various crystal structures.

[0003] However, currently, the preparation method of silicon carbide mainly uses the Acheson furnace method, but the Acheson furnace method has the following problems, such as high cost of synthetic precursors, complex reaction devices, large demand for carrier gas supply, and long reaction time, etc. Summary of the Invention

[0004] To solve at least one of the above technical problems, an embodiment of this application provides a waste insulator mandrel recycling system with a short reaction time and a simple reaction device.

[0005] In addition, an embodiment of this application also provides a recycling method using the waste insulator mandrel recycling system.

[0006] An embodiment of this application provides a waste insulator mandrel recycling system, including a reaction vessel, electrodes, and a power supply. The reaction vessel is used to accommodate a premix containing waste insulator mandrels and a conductive material. There are two electrodes, which are arranged opposite to each other in the reaction vessel and are configured to contact the premix. The power supply is electrically connected to the electrodes and is configured to form a discharge path with the conductive material. The power supply is configured to apply a current to the electrodes to cause the discharge path to short-circuit and generate heat.

[0007] In some embodiments of this application, the conductive material includes conductive graphite.

[0008] In some embodiments of this application, the recycling system further includes a vacuum device. The vacuum device includes a vacuum pump and a cavity. The reaction vessel is placed in the cavity, and the vacuum pump is configured to adjust the cavity to a vacuum state.

[0009] In some embodiments of this application, the vacuum device further includes conductive columns. The conductive columns are arranged on opposite sides of the cavity, and both ends of the conductive columns are respectively connected to the power supply and the electrodes.

[0010] In some embodiments of the present application, the reaction vessel includes a first end and a second end. Two electrodes are respectively disposed on the first end and the second end. The reaction vessel and the two electrodes together form a placement cavity, and the placement cavity is configured to place the premix.

[0011] In some embodiments of the present application, the reaction vessel is a quartz tube.

[0012] In some embodiments of the present application, the electrode is a graphite felt.

[0013] The embodiments of the present application also provide a method for recycling waste insulator core rods, which is applied to the aforementioned waste insulator core rod recycling system. The recycling method includes the following steps: mixing waste insulator core rods and a conductive material to obtain a premix. Under a vacuum state, applying a current to the premix to cause a reduction reaction between the waste insulator core rods and the conductive material to obtain a first mixture. Purifying the first mixture to obtain silicon carbide.

[0014] In some embodiments of the present application, the current value of the applied current is 5 A to 9 A. The time for applying the current is 40 s to 90 s.

[0015] In some embodiments of the present application, the pretreatment includes the following steps: sequentially cutting, crushing, and sieving the waste insulator core rods. Calcining the sieved waste insulator core rods and mixing the calcined waste insulator core rods with the conductive material to obtain a premix.

[0016] Compared with the prior art, the waste insulator core rod recycling system provided by the embodiments of the present application is provided with a reaction vessel for accommodating waste insulator core rods and a conductive material, and a current is applied to the reaction vessel. Through the high thermal effect of the resistance, a high temperature is generated in the reaction vessel instantaneously when the current is applied, and silicon carbide can be synthesized in a very short time. The waste insulator core rod recycling system provided by the present application has low cost and wide use, realizing the recycling of glass fiber materials and the rapid preparation of silicon carbide. Description of the Drawings

[0017] Figure 1 is a schematic diagram of a waste insulator core rod recycling system according to an embodiment of the present application.

[0018] Figure 2 is a process flow diagram of a waste insulator core rod recycling method according to an embodiment of the present application.

[0019] Figure 3 is an XRD pattern of Example 1 of the present application.

[0020] Figure 4 is an XRD pattern of Example 2 of the present application.

[0021] Description of Main Component Symbols: Reaction vessel 100, electrode 200, power supply 300, vacuum device 400, cavity 401, conductive column 402, first end 101, second end 102, placement cavity 103, gas cylinder 403, placement plate 404, vacuum pump 405. Detailed implementation manners

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0023] In order to solve the problems existing in the existing silicon carbide preparation methods, such as high cost of synthetic precursors, complex reaction devices, large demand for carrier gas supply, long reaction time, high energy consumption, many impurities in the products, and difficulty in controlling the morphology, etc. The inventors of the present application have found that rapid preparation of silicon carbide can be achieved through the resistance heating effect.

[0024] In view of this, please refer to Figure 1 , the embodiment of the present application aims to provide a recycling system for waste insulator core rods, including a reaction vessel 100, an electrode 200, and a power supply 300. The reaction vessel 100 is used to accommodate a premix containing waste insulator core rods and a conductive material. There are two electrodes 200, and the two electrodes 200 are oppositely arranged in the reaction vessel 100 and are configured to contact the premix. The power supply 300 is electrically connected to the electrode 200 and is configured to form a discharge path with the conductive material. The power supply 300 is configured to apply a current to the electrode 200 to cause the discharge path to short-circuit and generate heat. By providing a reaction vessel 100 for accommodating waste insulator core rods and a conductive material, and applying a current to the reaction vessel 100. Through the high heat effect of the resistance, a high temperature can be generated in the reaction vessel 100 at the moment when the current is applied, and silicon carbide can be synthesized in an extremely short time. There is no need for a heating device, and the gas supply demand is low, which further improves the utilization rate of the power supply 300, simplifies the reaction device, and thus reduces the preparation cost of silicon carbide. At the same time, it has the value of application and promotion in the field of recycling and reuse of waste insulator core rods.

[0025] In an embodiment of the present application, the conductive material is conductive graphite. In some embodiments, the conductive material is graphite powder. The particle size of the graphite powder is from 2000 mesh to 5000 mesh. For example, the particle size can be 2000 mesh, 3000 mesh, 4000 mesh, 5000 mesh or any value within the range formed by any two of the above values. The ash content of the graphite powder < 0.2. The expansion degree of the graphite powder is 150 to 400. For example, the expansion degree can be 150, 180, 200, 250, 300, 350, 400 or any value within the range formed by any two of the above values. By setting the conductive material as conductive graphite, it can be mixed with the waste insulator core rod and synthesize silicon carbide through the resistance heating effect.

[0026] Please refer to Figure 1 , in an embodiment of the present application, the recovery system further includes a vacuum device 400. The vacuum device 400 includes a vacuum pump 405 and a cavity 401. The reaction vessel 100 is placed in the cavity 401. The vacuum pump 405 is configured to adjust the cavity 401 to a vacuum state. By setting the vacuum device 400, the air pressure in the cavity 401 can be effectively adjusted, and the cavity 401 is placed in a vacuum state. In a vacuum environment, the reaction process is more stable, and impurities introduced during the reaction can also be excluded, which affects the purity and performance of silicon carbide. In some embodiments, the air pressure in the cavity 401 can be 0.1 atm. Specifically, the vacuum device 400 further includes a gas cylinder 403, and the gas cylinder 403 is used to control the air pressure in the cavity 401 to be 0.1 atm. A placement plate 404 is further provided in the cavity 401 for placing the reaction vessel 100 to prevent high temperature from damaging the vacuum device 400. The placement plate 404 can be an alumina plate.

[0027] Please refer to Figure 1 , in an embodiment of the present application, the vacuum device 400 further includes conductive columns 402. The conductive columns 402 are arranged on opposite sides of the cavity 401. Two ends of the conductive columns 402 are respectively connected to a power supply 300 and an electrode 200. By providing the conductive columns 402 in the vacuum device 400, the electrical connection between the cavity 401 and the outside can be realized, ensuring that the power supply 300 can stably supply power to the reaction vessel 100. The connection mode of the conductive columns 402 and the cavity 401 can effectively isolate the interference of the external environment on the reaction vessel 100. The setting of the conductive columns 402 can also facilitate the connection between the power supply 300 and the reaction vessel 100, simplify the operation process, and improve the overall efficiency of the recovery system.

[0028] Please refer to Figure 1, in an embodiment of the present application, the reaction vessel 100 includes a first end 101 and a second end 102, and two electrodes 200 are respectively disposed on the first end 101 and the second end 102. The reaction vessel 100 and the two electrodes 200 together form a placement cavity 103, and the placement cavity 103 is configured to place the premix. The setting of the electrode 200 can efficiently convert electrical energy into heat energy by means of short-circuit heating through a discharge path, thereby heating the waste insulator core rod and the conductive material and promoting the formation of silicon carbide.

[0029] In an embodiment of the present application, the reaction vessel 100 is a quartz tube. In some embodiments, the inner diameter of the quartz tube is 8 mm, the outer diameter is 12 mm, and the length is 3.5 mm. The high temperature resistance of the quartz tube can ensure that it will not decompose under high temperature conditions and avoid interfering with the reaction process.

[0030] In an embodiment of the present application, the electrode 200 is a graphite felt. In some embodiments, the graphite felt is a flexible graphite felt with rich internal pores. By using a graphite felt with rich internal pores, it is beneficial to the discharge of gas in the reaction vessel 100. By using graphite felt as the electrode 200 material, the excellent electrical conductivity and high temperature stability of graphite can be utilized to ensure the stability of the electrode 200 under high temperature conditions.

[0031] Compared with the prior art, the waste insulator core rod recovery system provided by the embodiments of the present application has the following beneficial effects: 1. By using the waste insulator core rod as a raw material, the use of high-cost precursors in the traditional method is reduced, and the raw material cost of preparing silicon carbide is significantly reduced.

[0032] 2. By providing a reaction vessel 100 for accommodating the waste insulator core rod and the conductive material and applying an electric current to the reaction vessel 100. Through the high heat effect of the resistance, a high temperature is generated in the reaction vessel 100 at the moment when the current is applied, and silicon carbide can be synthesized in a very short time. The problem of low thermal energy conversion efficiency in the traditional Acheson furnace method is improved.

[0033] 3. The waste insulator core rod recovery system provided by the present application is low-cost and widely used, realizing the recycling of glass fiber materials and the rapid preparation of silicon carbide.

[0034] Please refer to Figure 2 As shown, the waste insulator core rod recovery system provided by the embodiments of the present application specifically includes the following steps: Step 1: Mix the waste insulator core rod and the conductive material to obtain a premix.

[0035] In some embodiments, the pretreatment includes the following steps: successively cutting, pulverizing, and sieving the waste insulator core rods. The sieved waste insulator core rods are calcined, and the calcined waste insulator core rods are mixed with a conductive material to obtain a premix.

[0036] In some embodiments, the waste insulator core rods are cut into thin slices with a thickness ≤ 3 mm, and the thin slices are put into a pulverizer and pulverized into a powder with a micron-sized particle size and sieved three times. The sieved powder is calcined at a temperature of 600 °C to 700 °C for 5 h to 6 h. By calcining the powder, the epoxy resin matrix therein can be decomposed to obtain glass fiber powder.

[0037] In some embodiments, the thickness of the thin slices can be 1 mm, 2 mm, 3 mm, or any value within the range formed by any two of the above values. The particle size of the pulverized powder is 100 μm to 200 μm. For example, the particle size can be 100 μm, 150 μm, 200 μm, or any value within the range formed by any two of the above values. The mesh number of the sieve for sieving is 80 mesh to 100 mesh. For example, the mesh number of the sieve can be 80 mesh, 90 mesh, 100 mesh, or any value within the range formed by any two of the above values.

[0038] In some embodiments, the weight ratio of the pretreated waste insulator core rods to the conductive material is 1.25:1. In some embodiments, the conductive material is graphite powder with a mesh number of 5000.

[0039] In some embodiments, mixing the pretreated waste insulator core rods and the conductive material specifically means mixing the pretreated powder and the conductive material according to the mass ratio and fully stirring evenly at a rotation speed of 400 r / min to 500 r / min, and heating to 60 °C to 70 °C and maintaining for 6 h to 8 h to obtain a premix. For example, the rotation speed can be 400 r / min, 450 r / min, 500 r / min, or any value within the range formed by any two of the above values. The heating temperature can be 60 °C, 65 °C, 70 °C, or any value within the range formed by any two of the above values. The heating time can be 6 h, 7 h, 8 h, or any value within the range formed by any two of the above values. Specifically, the stirring is ball milling. By heating to this temperature range, the alcohol in the powder can be removed to obtain a glass fiber material with higher purity.

[0040] Step Two: Under a vacuum state, an electric current is applied to the premix to cause a reduction reaction between the waste insulator core rods and the conductive material to obtain a first mixture.

[0041] In some embodiments, the current value of the applied current is 5 A to 9 A. The time for applying the current is 40 s to 90 s.

[0042] In some embodiments, the current value can be 5 A, 6 A, 7 A, 8 A, 9 A, or any value within the range formed by any two of the above values. The time for applying the current can be 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, or any value within the range formed by any two of the above values. When the current value is 5 A and the time for applying the current is 90 s, cubic phase 3C-silicon carbide with a single crystal phase can be prepared. When the current value is 9 A and the time for applying the current is 40 s, hexagonal phase 6H-silicon carbide with a single crystal phase can be prepared. By controlling the applied current and the time for applying the current, the synthetic crystal phase of silicon carbide can be controlled.

[0043] In some embodiments, the premix is loaded into the reaction vessel 100, and the premix is pressed tightly within the reaction vessel 100 through the electrode 200 sheets. In some embodiments, the reaction vessel 100 is a quartz tube. The inner diameter of the quartz tube is 8 mm, the outer diameter is 12 mm, and the length is 3.5 mm. The high temperature resistance of the quartz tube can ensure that it will not decompose under high temperature conditions, avoiding interference with the reaction process.

[0044] In some embodiments, the resistance at both ends of the premix is 10 Ω to 15 Ω. For example, the resistance value can be 10 Ω, 11 Ω, 12 Ω, 13 Ω, 14 Ω, 15 Ω, or any value within the range formed by any two of the above values.

[0045] In some embodiments, the vacuum state is adjusted to 0.1 atm.

[0046] Step 3: Purify the first mixture to obtain silicon carbide.

[0047] In some embodiments, the purification treatment specifically includes the following steps: calcine the first mixture at a temperature of 600 °C to 700 °C for 6 h to 7 h. Add the calcined powder to an alkaline solution and stir evenly. The stirring temperature is 60 °C to 70 °C, and keep the temperature constant for reaction for 5 h to 6 h, and then carry out water washing, filtration, and drying in sequence to obtain silicon carbide powder. Excess graphite powder can be removed by high-temperature calcination, and excess impurities can be removed by alkali washing to obtain pure silicon carbide powder.

[0048] In some embodiments, the calcination temperature can be 600 °C, 650 °C, 700 °C, or any value within the range formed by any two of the above values. The stirring temperature can be 60 °C, 65 °C, 70 °C, or any value within the range formed by any two of the above values. The time for keeping the temperature constant for reaction can be 5 h, 5.5 h, 6 h, or any value within the range formed by any two of the above values.

[0049] In some embodiments, the drying temperature is 60 °C to 70 °C, and the drying time is 5 h to 6 h. For example, the drying temperature can be 60 °C, 65 °C, 70 °C, or any value within the range formed by any two of the above values. The drying time can be 5 h, 5.5 h, 6 h, or any value within the range formed by any two of the above values.

[0050] The foregoing waste insulator core rod recycling system is further described below through specific embodiments.

[0051] Example 1 Step 1: Cut the waste insulator core rod into thin slices with a thickness ≤ 3 mm, then put the thin slices into a pulverizer and pulverize them into fine powder with a particle size of 150 μm. Pass through an 80-mesh sieve three times. After the first two sievings, grind the unsieved powder for 5 min and sieve again to reduce raw material loss. Put the sieved core rod powder into a muffle furnace and calcine it at 700 °C for 6 h to decompose the epoxy resin matrix therein, obtaining glass fiber powder. Mix the glass fiber powder and graphite powder according to a weight ratio of 1.25:1 and ball-mill them at a speed of 450 r / min for 10 h to fully mix them, and then heat them to 60 °C in air and keep it for 6 h to remove alcohol, obtaining a premix.

[0052] Step 2: Put the premix into a quartz tube with an inner diameter of 8 mm, an outer diameter of 12 mm, and a length of 3.5 mm. Place the porous graphite felt as electrode 200 symmetrically on both sides of the sample, insert wires at both ends to press the premix tightly, and use a multimeter to measure the resistance at both ends as 10 Ω. Place the reaction vessel 100 on an alumina plate and put it into the vacuum device 400, and connect it to the DC high-voltage power supply 300 through the conductive columns 402 at both ends of the vacuum chamber.

[0053] Step 3: Turn on the vacuum pump 405 to pump away 90% of the gas in the cavity 401, and adjust the atmosphere in the cavity 401 to 0.1 atm.

[0054] Step 4: Set the current magnitude to 5 A, turn on the power supply 300, the reactants instantly turn red-hot, the insulator core rod powder reacts with graphite by reduction, and after maintaining for 90 s, cut off the power supply 300 to obtain silicon carbide powder containing impurities, and take out the sample after the product cools down to room temperature.

[0055] Step 5: Put the sample into a crucible and calcine it in a muffle furnace at 700 °C for 6 h to remove the excess graphite powder. Subsequently, adopt the method of chemical alkali washing. Put the sample into a three-necked flask, add 5 mL of 3.5 mol / L NaOH solution, start the heating magnetic stirrer to stir the powder and the NaOH solution evenly, make it react at a constant temperature of 60 °C for 5 h, wash it with water until neutral and then filter. Take down the silicon carbide powder on the filter paper and the filter paper together, and put them into a drying oven, dry them in the air at 60 °C for 6 h to obtain pure silicon carbide powder.

[0056] Example 2 Step 1: Cut the waste insulator core rod into thin slices with a thickness ≤ 3 mm, then put the thin slices into a pulverizer and pulverize them into fine powder with a particle size of 150 μm. Pass through an 80-mesh sieve in three times. After the first two sievings, grind the un-sieved powder for 5 min respectively and then sieve again to reduce the raw material loss. Put the sieved core rod powder into a muffle furnace and calcine it at 700 °C for 6 h to decompose the epoxy resin matrix therein to obtain glass fiber powder. Mix the glass fiber powder and graphite powder according to a weight ratio of 1.25:1 and ball-mill them at a speed of 450 r / min for 10 h to mix them evenly. Then heat it to 60 °C in the air and keep it for 6 h to remove the alcohol to obtain a premix.

[0057] Step 2: Put the premix into a quartz tube with an inner diameter of 8 mm, an outer diameter of 12 mm and a length of 3.5 mm. Place the loose and porous graphite felt symmetrically on both sides of the sample as electrode 200, insert wires at both ends to press the premix tightly, and use a multimeter to measure the resistance at both ends as 10 Ω. Place the reaction vessel 100 on an alumina plate and put it into a vacuum device 400, and connect it to a DC high-voltage power supply 300 through the conductive columns 402 at both ends of the vacuum chamber.

[0058] Step 3: Turn on the vacuum pump 405 to pump away 90% of the gas in the cavity 401 and adjust the atmosphere in the cavity 401 to 0.1 atm.

[0059] Step 4: Set the current size to 9 A, turn on the power supply 300, the reactants turn red-hot instantly, the insulator core rod powder and graphite undergo a reduction reaction. After maintaining for 40 s, cut off the power supply 300 to obtain silicon carbide powder containing impurities, and take out the sample after the product cools down to room temperature.

[0060] Step 5: Place the sample into a crucible and calcine it in a muffle furnace at 700 °C for 6 h to remove the excess graphite powder. Subsequently, adopt the method of chemical alkali washing. Put the sample into a three-necked flask, add 5 mL of 3.5 mol / L NaOH solution, start the heating magnetic stirrer to stir the powder and the NaOH solution evenly, make it react at a constant temperature of 60 °C for 5 h, wash it with water until neutral and then filter. Take down the silicon carbide powder on the filter paper and the filter paper together, and put them into a drying oven, dry them in the air at 60 °C for 6 h to obtain pure silicon carbide powder.

[0061] Perform the following tests on the silicon carbide powders obtained in Examples 1-2.

[0062] 1. Perform XRD tests on the silicon carbide powders obtained in Examples 1-2. Exemplarily, the XRD pattern of the silicon carbide powder in Example 1 is as Figure 3 shown. The XRD pattern of the silicon carbide powder in Example 2 is as Figure 4 shown. From Figure 3 and Figure 4 it can be seen that when the current value is 5 A and the current application time is 90 s, a single-crystalline-phase cubic-phase 3C-SiC can be prepared. When the current value is 9 A and the current application time is 40 s, a single-crystalline-phase hexagonal-phase 6H-SiC can be prepared. By controlling the applied current and the current application time, the synthetic crystal phase of silicon carbide can be controlled.

[0063] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A recycling system for waste insulator cores, characterized in that, Comprising: A reaction vessel for containing a premix comprising the waste insulator core rod and the conductive material; Electrodes, two of which are provided, and the two electrodes are oppositely arranged in the reaction vessel and configured to contact the premix; And A power supply, electrically connected to the electrodes and configured to form a discharge path with the conductive material, and the power supply is configured to apply a current to the electrodes to cause the discharge path to short-circuit and generate heat.

2. The recycling system for the waste insulator core rod according to claim 1, wherein, The conductive material includes conductive graphite.

3. The recycling system for waste insulator core rods according to claim 1, wherein It further includes a vacuum device, the vacuum device includes a vacuum pump and a cavity, the reaction vessel is placed in the cavity, and the vacuum pump is configured to adjust the cavity to a vacuum state.

4. The recycling system for waste insulator cores according to claim 3, wherein The vacuum device further includes conductive columns, the conductive columns are arranged on opposite sides of the cavity, and both ends of the conductive columns are respectively connected to the power supply and the electrodes.

5. The recycling system for waste insulator cores according to claim 1, characterized in that, The reaction vessel includes a first end and a second end, and the two electrodes are respectively arranged on the first end and the second end. The reaction vessel and the two electrodes together form a placement cavity, and the placement cavity is configured to place the premix.

6. The recycling system for waste insulator core rods according to claim 5, characterized in that, The reaction vessel is a quartz tube.

7. The recycling system for the used insulator core rod according to claim 1, wherein The electrodes are graphite felts.

8. A method for recycling waste insulator core rods, characterized in that, Applied to the recycling system of the waste insulator core rod according to any one of claims 1-7, the recycling method includes the following steps: Mix the waste insulator core rod and the conductive material to obtain a premix; Under a vacuum state, apply a current to the premix to cause a reduction reaction between the waste insulator core rod and the conductive material to obtain a first mixture; Purify the first mixture to obtain silicon carbide.

9. The recycling method of the waste insulator core rod according to claim 8, characterized in that, The current value of the applied current is 5 A to 9 A; The time for applying the current is 40 s to 90 s.

10. The recycling method of the waste insulator core rod according to claim 8, characterized in that, The pretreatment includes the following steps: Cut, crush and screen the waste insulator core rod in sequence; Calcine the sieved waste insulator core rod and mix the calcined waste insulator core rod with the conductive material to obtain the premix.

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