Carbon anode plate for preparing fluorine as well as preparation method and application of carbon anode plate

Abstract

The invention provides a carbon anode plate for fluorine preparation and a preparation method and application thereof, and belongs to the technical field of carbon anode plates. Eutectic prepared from aluminum fluoride, calcium fluoride and lithium fluoride is mixed with carbon nanotube / carbon black aggregate particles, needle coke and medium-temperature coal pitch, a carbon anode plate is prepared through a conventional carbon plate manufacturing process, carbon chemical vapor deposition and copper electroplating are performed on the surface, and the carbon anode plate for fluorine preparation is prepared. The preparation method of the carbon anode plate for fluorine preparation is simple, the generation of polarization of the carbon anode plate is prevented, and the carbon anode plate has the advantages of low porosity, low ash content, high mechanical strength, high volume density, obviously prolonged service life, low resistivity and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of carbon anode plates, and in particular to a carbon anode plate for fluorine production and a preparation method and application thereof. Background Art

[0002] Elemental fluorine is an indispensable main raw material in the field of semiconductor manufacturing. The production of fluorine gas generally adopts the medium-temperature electrolysis method. The anode plate material used in the medium-temperature electrolytic cell is an important electrode product for fluoride electrolysis. Since elemental fluorine is extremely active, the fluorine production technology and safety devices are difficult and demanding. The characteristics of electrodes used for electrolytic fluorine production are: good resistance to fluorine and hydrogen fluoride corrosion, low resistivity, good electrolyte wettability, low overvoltage, high mechanical strength, long-term use at high current density, high specific gravity, partial crushing into fragments that can sink to the bottom of the electrolytic cell to avoid inter-electrode short circuit, easy manufacturing, low price, etc.

[0003] The manufacturing method of the carbon anode material of the medium-temperature electrolytic fluorine electrolyzer is to mix ground calcined petroleum coke and coal tar pitch in a certain proportion, and then form and roast them (there are also secondary or multi-cold impregnation and roasting). The disadvantage of this manufacturing method is that due to the insufficient strength of the carbon anode, when the electrolytic cell is running for a long time, a CF polymer layer is formed on the surface of the carbon anode, causing the resistance to increase, and it is easy to produce anode polarization, carbon anode fracture and other phenomena, and produce a large amount of impurity gas, which reduces the use time of the carbon anode, prolongs the production cycle, and increases the production cost; and in the process of processing the carbon anode plate, tail gas is generated, causing production environmental pollution. Or it is the anode effect or polarization of the carbon anode. The so-called polarization refers to the reaction of the fluorine gas generated in the electrolytic cell with the graphitized components in the carbon anode during the electrolytic fluorine production, and the formation of a fluorinated carbon compound (CF) x film layer with poor insulation or conductivity on the surface of the carbon anode, which hinders the movement of electrons and significantly reduces the wetting performance of the KF-2HF electrolyte on the anode.

[0004] Chinese invention patent CN102502574B discloses a method for preparing a carbon anode plate, but the strength is not high, with a bending strength of 20-30 MPa. In order to further improve the ability to resist the internal stress caused by intercalation, the strength needs to be further improved. Summary of the invention

[0005] The purpose of the present invention is to propose a carbon anode plate for fluorine production and its preparation method and application. The preparation method is simple, prevents the polarization of the carbon anode plate, has the advantages of low porosity, low ash content, high mechanical strength, high volume density, etc., significantly improved service life, low resistivity, etc., and has broad application prospects.

[0006] The technical solution of the present invention is achieved in this way: The present invention provides a method for preparing a carbon anode plate for fluorine production. Aluminum fluoride, calcium fluoride and lithium fluoride are prepared to obtain a eutectic, which is mixed with carbon nanotube / carbon black aggregate particles, needle coke and medium-temperature coal tar pitch. A conventional carbon plate manufacturing process is used to prepare a carbon anode plate. Carbon chemical vapor deposition and copper electroplating are performed on the surface to obtain a carbon anode plate for fluorine production.

[0007] As a further improvement of the present invention, the following steps are included: S1. Preparation of eutectic: Aluminum fluoride, calcium fluoride and lithium fluoride are heated to melt, cooled and crystallized to obtain a eutectic; S2. Treatment of carbon nanotubes: adding multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid, heating to reflux with stirring, centrifuging, washing, and drying to obtain pretreated multi-walled carbon nanotubes; S3. Preparation of aggregated particles: adding pretreated multi-walled carbon nanotubes to water, spraying them into carbon black by powder injection technology, heating and stirring the reaction, and cooling to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: The needle coke, aggregated particles, and eutectic are uniformly mixed, and medium-temperature coal tar pitch is added, and the carbon anode plate is prepared by a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting; S5. Chemical vapor deposition: placing the obtained carbon anode plate in a chemical vapor deposition furnace, heating and pressurizing the mixed gas for deposition to obtain a deposited carbon anode plate; S6. Preparation of carbon anode plate for fluorine production: soaking the deposited carbon anode plate in a copper nitrate solution, electroplating, pyrolyzing, washing and drying to obtain the carbon anode plate for fluorine production.

[0008] As a further improvement of the present invention, in step S1, the mass ratio of aluminum fluoride, calcium fluoride and lithium fluoride is 3-5:2-3:1-2, the heating temperature is 1450-1550° C., and the heating time is 0.5-1 h.

[0009] As a further improvement of the present invention, the volume ratio of concentrated nitric acid to concentrated sulfuric acid in step S2 is 1:3-5, the solid-liquid ratio of the multi-walled carbon nanotubes to the mixed solution is 1:3-5 g / mL, and the heating reflux stirring reaction time is 3-5 h.

[0010] As a further improvement of the present invention, the mass ratio of the pretreated multi-walled carbon nanotubes and carbon black in step S3 is 3-4:7, the temperature of the heating and stirring reaction is 350-450° C., and the time is 0.5-1.5 h.

[0011] As a further improvement of the present invention, the mass ratio of the needle coke, aggregated particles, eutectic and medium-temperature coal tar pitch in step S4 is 60-80:5-10:3-5:20-30.

[0012] As a further improvement of the present invention, the mixed gas in step S5 is a mixture of propane and nitrogen, with a volume ratio of 3-6:3-6, a ventilation volume of 10-20 mL / min, and the temperature of the heated and pressurized deposition is 800-1200°C, the pressure is 2-4 kPa, and the time is 5-10 h.

[0013] As a further improvement of the present invention, the concentration of the copper nitrate solution in step S6 is 1-2 mol / L, and the current density of the electroplating is 0.5-1 mA / cm 2 , time is 5-15min, the pyrolysis temperature is 1050-1100°C, the pressure is <10Pa, and the time is 8-12h.

[0014] The present invention further protects a carbon anode plate for fluorine production obtained by the above-mentioned preparation method.

[0015] The present invention further protects the use of the above-mentioned carbon anode plate for fluorine production in the electrolytic preparation of fluorine gas.

[0016] The present invention has the following beneficial effects: The present invention prepares a carbon anode plate for fluorine production. Aluminum fluoride, calcium fluoride and lithium fluoride are used to prepare eutectic, carbon nanotube / carbon black aggregated particles and needle coke as raw materials, and medium-temperature coal tar pitch is used as a binder. The eutectic prepared by aluminum fluoride, calcium fluoride and lithium fluoride can inhibit the polarization of carbon electrodes. The surfaces of multi-walled carbon nanotubes are subjected to acidification treatment to form a large number of carboxyl groups, which form hydrogen bonds or other van der Waals forces with groups on the surface of carbon black. Aggregated particles are prepared by powder injection technology. The electrical conductivity of the carbon anode material is effectively improved without increasing the graphitization degree of the components of the carbon anode material, and the mechanical strength of the plate is improved. The prepared carbon anode plate has the advantages of uniform pores, high mechanical strength, low resistivity and the like.

[0017] The surface of the carbon anode is chemically vapor deposited to form a polarization-resistant coating, which has uniform thickness and is tightly bonded to the carbon anode substrate. The low-graphitization, difficult-to-polarize chemical vapor deposition pyrolytic carbon coating seals the surface gaps of the carbon plate to prevent the electrolyte from penetrating into the interior of the electrode, protects the internal structure of the electrode, and improves the anti-polarization performance of the carbon anode. Copper metal is introduced by electroplating, and a metal particle doping layer is formed on its surface, which is conducive to the formation of conductive ionic or semi-ionic graphite intercalation compounds during electrolytic fluorine production to prevent the formation of non-conductive fluorinated graphite, improve the surface conductivity, and effectively prevent the polarization of the carbon anode plate. It has the advantages of low porosity, low ash content, high mechanical strength, high volume density, etc., and its service life is significantly improved.

[0018] The carbon anode plate for fluorine production prepared by the present invention has a simple preparation method, prevents the occurrence of polarization of the carbon anode plate, has the advantages of low porosity, low ash content, high mechanical strength, high volume density, significantly improved service life, low resistivity, etc., and has broad application prospects. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Multi-walled carbon nanotubes, with a purity of >95%, a length of 0.5-2 μm, and a diameter of 50 nm, were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0021] Example 1 This embodiment provides a method for preparing a carbon anode plate for fluorine production, comprising the following steps: S1. Preparation of eutectic: 3 g aluminum fluoride, 2 g calcium fluoride, and 1 g lithium fluoride were heated to 1450°C, melt-stirred for 0.5 h, cooled to room temperature and crystallized to obtain eutectic; S2. Treatment of carbon nanotubes: 10 g of multi-walled carbon nanotubes was added to a mixture of 30 mL of concentrated nitric acid and concentrated sulfuric acid, heated under reflux with stirring for 3 h, centrifuged, washed, and dried to obtain pretreated multi-walled carbon nanotubes; The volume ratio of the concentrated nitric acid to the concentrated sulfuric acid is 1:3; S3. Preparation of aggregated particles: 3 g of pretreated multi-walled carbon nanotubes were added to 100 mL of water, sprayed into a furnace containing 7 g of carbon black by powder injection technology, heated to 350 ° C, stirred for 0.5 h, and cooled to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: 60g of needle coke, 5g of aggregated particles, and 3g of eutectic are mixed evenly, and 20g of medium-temperature coal tar pitch (the softening point of medium-temperature tar pitch is between 80-95°C) is added, and a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting, is used to prepare a carbon anode plate; S5. Chemical vapor deposition: placing the prepared carbon anode plate in a chemical vapor deposition furnace, passing a mixed gas with a flow rate of 10 mL / min, a temperature of 800°C, a pressure of 2 kPa, heating and pressurizing for 5 hours, wherein the mixed gas is a mixture of propane and nitrogen with a volume ratio of 6:3, to obtain a deposited carbon anode plate; S6. Preparation of carbon anode plate for fluorine production: The deposited carbon anode plate was immersed in 1 mol / L copper nitrate solution at a current density of 0.5 mA / cm 2Electroplating for 5 minutes, 1050°C, pressure <10Pa, pyrolysis for 8 hours, washing, drying, to obtain a carbon anode plate for fluorine production.

[0022] Example 2 This embodiment provides a method for preparing a carbon anode plate for fluorine production, comprising the following steps: S1. Preparation of eutectic: 5 g aluminum fluoride, 3 g calcium fluoride, and 2 g lithium fluoride were heated to 1550°C, melted and stirred for 1 h, cooled to room temperature and crystallized to obtain eutectic; S2. Treatment of carbon nanotubes: 10 g of multi-walled carbon nanotubes was added to a mixture of 50 mL of concentrated nitric acid and concentrated sulfuric acid, heated under reflux with stirring for 5 h, centrifuged, washed, and dried to obtain pretreated multi-walled carbon nanotubes; The volume ratio of the concentrated nitric acid to the concentrated sulfuric acid is 1:5; S3. Preparation of aggregated particles: 4 g of pretreated multi-walled carbon nanotubes were added to 100 mL of water, sprayed into a furnace containing 7 g of carbon black by powder injection technology, heated to 450°C, stirred for reaction for 1.5 h, and cooled to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: 80g of needle coke, 10g of aggregated particles, and 5g of eutectic are mixed evenly, and 30g of medium-temperature coal tar pitch (the softening point of medium-temperature tar pitch is between 95°C) is added, and a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting, is used to prepare a carbon anode plate; S5. Chemical vapor deposition: placing the prepared carbon anode plate in a chemical vapor deposition furnace, passing a mixed gas with a flow rate of 20 mL / min, a temperature of 1200°C, a pressure of 4 kPa, heating and pressurizing for 10 hours, wherein the mixed gas is a mixture of propane and nitrogen with a volume ratio of 3:6, to obtain a deposited carbon anode plate; S6. Preparation of carbon anode plate for fluorine production: The deposited carbon anode plate was immersed in 2 mol / L copper nitrate solution at a current density of 1 mA / cm 2 Electroplating for 15 minutes, 1100°C, pressure <10Pa, pyrolysis for 12 hours, washing, drying, to obtain a carbon anode plate for fluorine production.

[0023] Example 3 This embodiment provides a method for preparing a carbon anode plate for fluorine production, comprising the following steps: S1. Preparation of eutectic: 4 g aluminum fluoride, 2.5 g calcium fluoride, and 1.5 g lithium fluoride were heated to 1500°C, melted and stirred for 1 h, cooled to room temperature and crystallized to obtain eutectic; S2. Treatment of carbon nanotubes: 10 g of multi-walled carbon nanotubes was added to a mixture of 40 mL of concentrated nitric acid and concentrated sulfuric acid, heated under reflux with stirring for 4 h, centrifuged, washed, and dried to obtain pretreated multi-walled carbon nanotubes; The volume ratio of the concentrated nitric acid to the concentrated sulfuric acid is 1:4; S3. Preparation of aggregated particles: 3.5 g of pretreated multi-walled carbon nanotubes were added to 100 mL of water, sprayed into a furnace containing 7 g of carbon black by powder injection technology, heated to 400 ° C, stirred for 1 h, and cooled to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: 70g of needle coke, 7g of aggregated particles, and 4g of eutectic are mixed evenly, and 25g of medium-temperature coal tar pitch (the softening point of medium-temperature tar pitch is between 80-95°C) is added, and a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting, is used to prepare a carbon anode plate; S5. Chemical vapor deposition: placing the prepared carbon anode plate in a chemical vapor deposition furnace, passing a mixed gas with a flow rate of 15 mL / min, a temperature of 1000°C, a pressure of 3 kPa, heating and pressurizing for 7 hours, wherein the mixed gas is a mixture of propane and nitrogen with a volume ratio of 5:5, to obtain a deposited carbon anode plate; S6. Preparation of carbon anode plate for fluorine production: The deposited carbon anode plate was immersed in 1.5 mol / L copper nitrate solution at a current density of 0.7 mA / cm 2 Electroplating for 10 minutes, 1070°C, pressure <10Pa, pyrolysis for 10 hours, washing, drying, to obtain a carbon anode plate for fluorine production.

[0024] Comparative Example 1 Compared with Example 3, the difference is that aluminum fluoride is not added in step S1.

[0025] The details are as follows: S1. Preparation of eutectic: Heat 2.5 g of calcium fluoride and 1.5 g of lithium fluoride to 1500°C, melt and stir for 1 hour, cool to room temperature and crystallize to obtain eutectic.

[0026] Comparative Example 2 Compared with Example 3, the difference is that calcium fluoride is not added in step S1.

[0027] The details are as follows: S1. Preparation of eutectic: Heat 4 g aluminum fluoride and 1.5 g lithium fluoride to 1500°C, melt and stir for 1 hour, cool to room temperature for crystallization, and obtain eutectic.

[0028] Comparative Example 3 Compared with Example 3, the difference is that lithium fluoride is not added in step S1.

[0029] The details are as follows: S1. Preparation of eutectic: Heat 4 g aluminum fluoride and 2.5 g calcium fluoride to 1500°C, melt and stir for 1 hour, cool to room temperature for crystallization, and obtain eutectic.

[0030] Comparative Example 4 Compared with Example 3, the difference is that no eutectic is added in step S4.

[0031] The details are as follows: S4. Preparation of carbon anode plate: 70g of needle coke and 11g of aggregated particles were mixed evenly, and 25g of medium-temperature coal tar pitch (medium-temperature tar pitch softening point is between 80-95°C) was added, and the carbon anode plate was prepared through conventional carbon plate manufacturing processes, including crushing, kneading, molding, and roasting.

[0032] Comparative Example 5 Compared with Example 3, the difference is that the aggregated particles in step S4 are replaced by carbon black.

[0033] The details are as follows: S4. Preparation of carbon anode plate: 70g needle coke, 7g carbon black and 4g eutectic are mixed evenly, and 25g medium-temperature coal tar pitch (medium-temperature tar pitch softening point is between 80-95°C) is added, and the carbon anode plate is prepared through conventional carbon plate manufacturing process, including crushing, kneading, molding and roasting.

[0034] Comparative Example 6 Compared with Embodiment 3, the difference is that step S5 is not performed.

[0035] The details are as follows: S1. Preparation of eutectic: 4 g aluminum fluoride, 2.5 g calcium fluoride, and 1.5 g lithium fluoride were heated to 1500°C, melted and stirred for 1 h, cooled to room temperature and crystallized to obtain eutectic; S2. Treatment of carbon nanotubes: 10 g of multi-walled carbon nanotubes was added to a mixture of 40 mL of concentrated nitric acid and concentrated sulfuric acid, heated under reflux with stirring for 4 h, centrifuged, washed, and dried to obtain pretreated multi-walled carbon nanotubes; The volume ratio of the concentrated nitric acid to the concentrated sulfuric acid is 1:4; S3. Preparation of aggregated particles: 3.5 g of pretreated multi-walled carbon nanotubes were added to 100 mL of water, sprayed into a furnace containing 7 g of carbon black by powder injection technology, heated to 400 ° C, stirred for 1 h, and cooled to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: 70g of needle coke, 7g of aggregated particles, and 4g of eutectic are mixed evenly, and 25g of medium-temperature coal tar pitch (the softening point of medium-temperature tar pitch is between 80-95°C) is added, and a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting, is used to prepare a carbon anode plate; S5. Preparation of carbon anode plate for fluorine production: The carbon anode plate was immersed in 1.5 mol / L copper nitrate solution with a current density of 0.7 mA / cm 2Electroplating for 10 minutes, 1070°C, pressure <10Pa, pyrolysis for 10 hours, washing, drying, to obtain a carbon anode plate for fluorine production.

[0036] Comparative Example 7 Compared with the embodiment 3, the difference is that step S6 is not performed.

[0037] The details are as follows: S1. Preparation of eutectic: 4 g aluminum fluoride, 2.5 g calcium fluoride, and 1.5 g lithium fluoride were heated to 1500°C, melted and stirred for 1 h, cooled to room temperature and crystallized to obtain eutectic; S2. Treatment of carbon nanotubes: 10 g of multi-walled carbon nanotubes was added to a mixture of 40 mL of concentrated nitric acid and concentrated sulfuric acid, heated under reflux with stirring for 4 h, centrifuged, washed, and dried to obtain pretreated multi-walled carbon nanotubes; The volume ratio of the concentrated nitric acid to the concentrated sulfuric acid is 1:4; S3. Preparation of aggregated particles: 3.5 g of pretreated multi-walled carbon nanotubes were added to 100 mL of water, sprayed into a furnace containing 7 g of carbon black by powder injection technology, heated to 400 ° C, stirred for 1 h, and cooled to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: 70g of needle coke, 7g of aggregated particles, and 4g of eutectic are mixed evenly, and 25g of medium-temperature coal tar pitch (the softening point of medium-temperature tar pitch is between 80-95°C) is added, and a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting, is used to prepare a carbon anode plate; S5. Chemical vapor deposition: The prepared carbon anode plate is placed in a chemical vapor deposition furnace, and a mixed gas is passed through, with a flow rate of 15 mL / min, a temperature of 1000°C, a pressure of 3 kPa, and heated and pressurized deposition for 7 hours. The mixed gas is a mixture of propane and nitrogen in a volume ratio of 5:5, to obtain a carbon anode plate for fluorine production.

[0038] Test Example 1 The fluorine-using carbon anode plates prepared in Examples 1-3 of the present invention and Comparative Examples 1-7 were subjected to performance tests. The results are shown in Table 1.

[0039] The tensile strength, bending strength and shear strength of the prepared fluorine carbon anode plate were tested on a DSS-10T-S electronic universal testing machine; the compression strength was tested according to GB1994-88. The tensile specimen size is 104mm×6mm×6mm; the bending specimen size is 55mm×10mm×6mm; the shear specimen size is 50 / 10.5mm×4mm; the compression specimen size is 10mm×10mm×10mm Table 1

[0040] It can be seen from the above table that the carbon anode plates for fluorine prepared in Examples 1-3 of the present invention have good mechanical properties.

[0041] Test Example 2 The resistivity of the carbon anode plates for fluorine prepared in Examples 1-3 and Comparative Examples 1-7 of the present invention was tested using the JB / T8133.2-1999 standard. The sample size was 4 mm×8 mm×32 mm. The results are shown in Table 2.

[0042] Table 2

[0043] It can be seen from the above table that the carbon anode plates for fluorine prepared in Examples 1-3 of the present invention have lower resistivity.

[0044] Test Example 3 The porosity of the carbon anode plates for fluorine prepared in Examples 1-3 of the present invention and Comparative Examples 1-7 was tested, and the results are shown in Table 3.

[0045] Table 3

[0046] It can be seen from the above table that the carbon anode plates for fluorine prepared in Examples 1-3 of the present invention have lower porosity.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a carbon anode plate for fluorine production, characterized in that: Aluminum fluoride, calcium fluoride and lithium fluoride are used to prepare a eutectic, which is mixed with carbon nanotube / carbon black aggregate particles, needle coke and medium-temperature coal tar pitch. A carbon anode plate is prepared through a conventional carbon plate manufacturing process, and carbon chemical vapor deposition and copper electroplating are performed on the surface to obtain a carbon anode plate for fluorine production.

2. The preparation method according to claim 1, characterized in that: The following steps are involved: S1. Preparation of eutectic: Aluminum fluoride, calcium fluoride and lithium fluoride are heated to melt, cooled and crystallized to obtain a eutectic; S2. Treatment of carbon nanotubes: adding multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid, heating to reflux with stirring, centrifuging, washing, and drying to obtain pretreated multi-walled carbon nanotubes; S3. Preparation of aggregated particles: adding pretreated multi-walled carbon nanotubes to water, spraying them into carbon black by powder injection technology, heating and stirring the reaction, and cooling to room temperature to obtain aggregated particles; S4. Preparation of carbon anode plate: The needle coke, aggregated particles, and eutectic are uniformly mixed, and medium-temperature coal tar pitch is added, and the carbon anode plate is prepared by a conventional carbon plate manufacturing process, including crushing, kneading, molding, and roasting; S5. Chemical vapor deposition: placing the obtained carbon anode plate in a chemical vapor deposition furnace, heating and pressurizing the mixed gas for deposition to obtain a deposited carbon anode plate; S6. Preparation of carbon anode plate for fluorine production: soaking the deposited carbon anode plate in a copper nitrate solution, electroplating, pyrolyzing, washing and drying to obtain the carbon anode plate for fluorine production.

3. The preparation method according to claim 2, characterized in that: In step S1, the mass ratio of aluminum fluoride, calcium fluoride and lithium fluoride is 3-5:2-3:1-2, the heating temperature is 1450-1550° C., and the heating time is 0.5-1 h.

4. The preparation method according to claim 2, characterized in that: In step S2, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:3-5, the solid-liquid ratio of the multi-walled carbon nanotubes to the mixed solution is 1:3-5 g / mL, and the heating reflux stirring reaction time is 3-5 h.

5. The preparation method according to claim 2, characterized in that: In step S3, the mass ratio of the pretreated multi-walled carbon nanotubes to carbon black is 3-4:7, the temperature of the heating and stirring reaction is 350-450° C., and the time is 0.5-1.5 h.

6. The preparation method according to claim 2, characterized in that: The mass ratio of the needle coke, aggregated particles, eutectic and medium-temperature coal tar pitch in step S4 is 60-80:5-10:3-5:20-30.

7. The preparation method according to claim 2, characterized in that: The mixed gas in step S5 is a mixed gas of propane and nitrogen, with a volume ratio of 3-6:3-6, a ventilation volume of 10-20 mL / min, a temperature of 800-1200° C., a pressure of 2-4 kPa, and a time of 5-10 h.

8. The preparation method according to claim 2, characterized in that: The concentration of the copper nitrate solution in step S6 is 1-2 mol / L, and the current density of the electroplating is 0.5-1 mA / cm 2 , time is 5-15min, the pyrolysis temperature is 1050-1100°C, the pressure is <10Pa, and the time is 8-12h.

9. A carbon anode plate for fluorine production obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the carbon anode plate for fluorine production as claimed in claim 9 in preparing fluorine gas by electrolysis.

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