A method and device for efficiently preparing ultrafine anhydrous ferric phosphate

Abstract

The invention provides a method and equipment for efficiently preparing anhydrous ferric phosphate ultrafine powder. The method comprises the following steps: reacting an iron block with phosphoric acid to generate a Fe(H2PO4)2 solution, then adding hydrogen peroxide and a dispersant to carry out an oxidation reaction, and then carrying out a crystallization reaction to obtain a ferric phosphate crystal liquid. The crystal liquid is then subjected to filter pressing separation and flash drying to obtain FePO4·2H2O. Finally, the obtained FePO4·2H2O is introduced into a rapid thermal shock device for high-temperature electric explosion in an inert atmosphere. The current is 10-20A, the voltage is 20kV, and the duration of the current is 10-20s. Thus, anhydrous ferric phosphate ultrafine powder with a water content of less than 0.5% and a particle size of less than 500nm is obtained, which greatly saves the energy consumption and time loss of subsequent grinding. In addition, the high-temperature electric explosion method and the rapid thermal shock device in the invention combine the calcination and pulverization processes, which greatly reduces the total time and total energy consumption required for the entire process, and realizes the economical, energy-saving, efficient and rapid preparation of anhydrous ferric phosphate ultrafine powder.

Description

Technical Field

[0001] The present application relates to the technical field of iron phosphate production, and more specifically, to a method and equipment for preparing anhydrous iron phosphate. Background Art

[0002] As a positive electrode material for lithium batteries, lithium iron phosphate has the advantages of high safety, long life and environmental protection. The performance of lithium iron phosphate positive electrode materials is inseparable from its precursor iron phosphate. For the synthesis of iron phosphate, the current mainstream processes for iron phosphate precursors are "iron method" and "ammonium method", that is, "iron block and phosphoric acid" process or "ferrous sulfate and ammonium phosphate" process. The iron phosphate prepared by them generally has some crystal water and has larger particles. When used in lithium iron phosphate production, it needs to be dehydrated and ground to achieve anhydrous and smaller particle size. It is generally calcined at high temperature to remove the bound water in the synthesized hydrated iron phosphate crystals and use a mechanical mill or air flow mill to crush the calcined anhydrous iron phosphate.

[0003] For example, Chinese patent CN110562946A discloses a method for preparing anhydrous iron phosphate with a battery-grade flaky structure, which comprises the following steps: reacting reduced iron powder with a phosphoric acid solution at 0-40°C to generate a Fe(H2PO4)2 solution; adding an oxidant to the Fe(H2PO4)2 solution for an oxidation reaction, and then crystallizing, the crystallization being performed at 85-95°C for 1-3 hours to generate an iron phosphate precipitate; then performing solid-liquid separation, collecting the solid precipitate and washing it, and recycling the waste liquid obtained from the separation and washing; then drying the washed solid precipitate by air flow flash evaporation at a temperature of 180-200°C, and calcining the dried product at 500-700°C to obtain anhydrous iron phosphate in a flaky structure; the oxidant is a mixture of one or more of a hydrogen peroxide solution, ozone, and oxygen-enriched air; the obtained product has high purity, high tap density, and a good flaky structure, and can be used as a good precursor raw material for preparing lithium iron phosphate, a positive electrode material for lithium-ion batteries.

[0004] For another example, Chinese patent CN111377426A discloses a method for preparing anhydrous iron phosphate nanoparticles, comprising the following steps: adding iron powder to a phosphoric acid solution, heating to 40°C~50°C, keeping warm for 0.5h~1h, then adding an oxidant, and continuing to keep warm for 0.5h~1h; then filtering to obtain a filtrate, adding deionized water to the filtrate to adjust the iron ion concentration in the solution to 0.1mol / L~0.8mol / L, adding an oxidant, and stirring at room temperature for 1h~2h; filtering again, washing the filter cake until the filtrate is neutral, and drying; finally heating the powder, heating to 500°C~700°C, and keeping warm for 6~10h to obtain anhydrous nano-scale iron phosphate; the oxidant is hydrogen peroxide.

[0005] For another example, Chinese patent CN116902944A discloses a method for preparing layered nano-scale iron phosphate, which comprises the following steps: using battery-grade iron phosphate as a seed crystal and mixing it with a phosphoric acid solution to obtain an iron-phosphorus solution after filtering; sequentially adding hydrogen peroxide and elemental iron to the iron-phosphorus solution, mixing and reacting the mixture, and filtering to obtain an iron phosphate solution; then adding a dispersant to the iron phosphate solution, sequentially performing evaporation concentration and spray drying to obtain a granular material; then adding the granular material to pure water for aging and washing, filtering and collecting the filter residue, which is dihydrated iron phosphate; washing the dihydrated phosphoric acid, flash drying it, and then roasting it to obtain anhydrous iron phosphate; and finally pulverizing the anhydrous iron phosphate to obtain the layered nano-scale iron phosphate.

[0006] The above-mentioned methods for removing crystal water from ferric phosphate all adopt calcining the dry ferric phosphate powder to obtain it. In the prior art, other methods are also used to obtain anhydrous ferric phosphate, such as spray drying to obtain anhydrous nano-ferric phosphate.

[0007] For example, Chinese patent CN108046230A discloses a one-step method for preparing anhydrous nano iron phosphate, which comprises placing red iron oxide waste generated by a steel mill into a sealed reactor, introducing CO, reacting at a temperature of 300-350° C. and a pressure of 5-6 atmospheres for 5-6 hours, then reducing the temperature to 200° C., increasing the pressure to 150-200 atm, continuing to introduce CO for 2-3 hours, slowly releasing the pressure, and cooling the released gas to obtain carbonyl iron; keeping the phosphoric acid at a constant temperature of 70-95° C., and then spraying the carbonyl iron and phosphoric acid into the reactor simultaneously, the gas used for the spraying is air, the reactor is connected to a cyclone dust collector, and then collecting the materials in the cyclone dust collector, and vacuum packaging to obtain anhydrous nano iron phosphate.

[0008] In the above methods, the mainstream process generally removes the bound water present in the synthesized hydrated iron phosphate crystals by high-temperature calcination. This method is time-consuming, and the crystals will inevitably grow and agglomerate during the heating process. In addition, in order to obtain the required particle size of iron phosphate particles, further pulverization is required, and the energy consumption of the two steps of calcination and pulverization accounts for more than 80% of the total energy consumption of the entire iron phosphate preparation; the spray drying method requires the iron source to be converted into a liquid substance that is easily reduced to iron powder, which complicates the process and only obtains anhydrous iron phosphate. Like high-temperature calcination, it also requires additional pulverization; in addition, spray drying generally has a high-speed centrifugal disk or a high-pressure air atomization disk, which requires a large amount of energy to support the operation, and the iron phosphate is broken into 2~15μm. Generally, an airflow superfine pulverizer is used. This method requires the introduction of an airflow source of 6~8 atmospheres, which requires a large amount of energy and gas source. Therefore, a new method and device are needed to improve the problem of long time and high energy consumption in the calcination and pulverization steps. Summary of the invention

[0009] In order to overcome the shortcomings and deficiencies in the prior art, the present invention provides a method and equipment for efficiently preparing ultrafine anhydrous ferric phosphate powder, wherein the method for preparing ultrafine anhydrous ferric phosphate powder is carried out by subjecting an ferric phosphate precursor to high-temperature electric explosion, and the high-temperature electric explosion process and equipment combine the calcination and crushing processes to obtain anhydrous particles of ultrafine powder in one step, which reduces a large amount of energy and gas consumption, greatly reduces the total time required for the entire process, and realizes economical, energy-saving, efficient and rapid preparation of ultrafine anhydrous ferric phosphate powder.

[0010] The present invention provides a method for efficiently preparing ultrafine anhydrous ferric phosphate powder, comprising the steps of iron dissolving, oxidation, crystallization, drying and calcining, and the specific steps are as follows:

[0011] (1) Add the iron block to a 25% by mass phosphoric acid solution and heat to 90°C to perform a molten iron reaction. After 8 hours of reaction, measure the Fe(H2PO4)2 content in the solution. When the mass fraction of Fe(H2PO4)2 in the solution is 18-20%, filter the reaction solution to obtain a Fe(H2PO4)2 solution.

[0012] (2) Heat the Fe(H2PO4)2 solution to 35°C, start stirring, add hydrogen peroxide, react for 60 minutes, continue stirring, add dispersant, and continue until the reaction is complete to obtain an oxidized solution;

[0013] (3) adding distilled water to the oxidized solution, stirring for 5 to 10 minutes, heating to 70 to 90°C, and keeping the temperature for 50 to 70 minutes to obtain a ferric phosphate crystal solution;

[0014] (4) separating the hydrolyzed ferric phosphate crystal liquid by filter pressing, washing the filtered solid phase by centrifugation, collecting the washed liquid and measuring its pH value, and completing the centrifugal washing when the pH value of the washed liquid is between 5.9 and 6.1, and flash drying the solid ferric phosphate after centrifugation to obtain FePO4·2H2O;

[0015] (5) Under an inert atmosphere, the prepared FePO4·2H2O was introduced into a rapid thermal shock device for high-temperature electric explosion at a current of 10-20A, a voltage of 20kV, and a duration of 10-20s to obtain ultrafine anhydrous iron phosphate powder.

[0016] In the method of the present invention, the reaction is terminated when the mass fraction of Fe(H2PO4)2 in the solution is 18-20% in order to avoid further reaction to produce other impurities.

[0017] The molar ratio of iron block to phosphoric acid is 0.975:1.

[0018] The molar ratio of hydrogen peroxide to iron block is 0.5:1.

[0019] The dispersant is a polyethylene glycol solution with a mass fraction of 30-55%, and the molar ratio of its addition to the iron block is 0.08:1. Polyethylene glycol is a good surfactant that can improve the interface problem of the material, and can also prevent the sedimentation and agglomeration of particles to form more uniform particles.

[0020] The flash drying temperature is 180~200℃ and the time is 1~2h.

[0021] The obtained ultrafine anhydrous ferric phosphate powder has a water content of less than 0.5% and a particle size of less than 500 nm, which is much smaller than that of conventional ultrafine anhydrous ferric phosphate.

[0022] The inert gas used in the high-temperature electric explosion is argon or nitrogen.

[0023] The instantaneous temperature of the high-temperature electric explosion reaches 1800°C. Through instant high temperature and high pressure, the bound water in the hydrated iron phosphate is quickly released in the form of electric explosion, and while removing the water, ultrafine anhydrous iron phosphate particles are prepared.

[0024] In addition, the equipment used in the method of the present invention includes a rapid thermal shock device and a post-processing device used for high-temperature electric explosion: the rapid thermal shock device is composed of a raw material storage tank, a discharge port, a heating zone, a sinking zone, and a discharge port from top to bottom; the post-processing device is connected to a blower, a classifier, a screen and a product storage tank in sequence at the discharge port of the rapid thermal shock device.

[0025] The outer shells of the heating zone and the sinking zone are high-temperature heat-insulating outer cylinders, and a heat-conducting explosion-proof cavity wall is arranged inside the high-temperature heat-insulating outer cylinder.

[0026] The heating zone is provided with dispersing blades, an inert gas inlet and an electrified screen, wherein the dispersing blades and the inert gas inlet are connected to the discharge port, and the electrified screen is laid flat at a position 1 / 3 from the top of the heating zone, and the height is 1 / 8 of the total height of the heating zone.

[0027] A heating ring and a constant temperature insulation layer are arranged between the heat-conducting explosion-proof cavity wall and the high-temperature insulation outer cylinder in the sinking area, wherein the heating ring is arranged close to the side of the high-temperature insulation outer cylinder, and the constant temperature insulation layer is arranged close to the side of the heat-conducting explosion-proof cavity wall.

[0028] The sinking area is also provided with an air filter valve, which connects the sinking area with the external environment through the heat-conducting explosion-proof cavity wall, the constant temperature insulation layer, the heating ring and the high-temperature insulation outer cylinder.

[0029] The dispersing blade raw materials are kept in a dispersed state in the heating chamber, and the electrified screen is the reaction area, which contacts with the dispersed solid powder, so that the raw materials are dehydrated under high temperature and high pressure, and ultra-fine solid particles are produced at the same time.

[0030] The heat-conducting explosion-proof cavity wall ensures that the heating cavity is not affected by the impact of high-temperature electric explosions, while withstanding instantaneous high temperatures of up to 1800°C; the high-temperature insulating outer cylinder isolates the high-temperature inner wall from the natural environment, keeping the equipment in a safe state.

[0031] The air filter valve ensures the partial pressure inside and outside the container and discharges the generated water vapor naturally.

[0032] The heating ring and the constant temperature insulation layer are used to keep the sedimentation area stably at 80~90℃, to keep the moisture produced by the reaction in the form of water vapor for easy discharge through the air filter valve, and to keep the solid particles after the reaction in a dry state.

[0033] In the rapid thermal shock device of the present invention, solid powder is fed into the raw material storage tank from the top feed port, and the solid powder is dispersed at the top of the heating zone by the dispersing blades, falling in the form of dust, and completing the decomposition process under the high temperature and high pressure conditions of the energized screen. After being crushed, it falls freely under the blowing of inert gas and accumulates at the bottom of the sedimentation area, and is transmitted to the product storage tank through the pipeline in sequence through the blower, the classifier, and the screen. At the same time, the air filter valve equipped in the sedimentation area ensures the partial pressure inside and outside the container, and the generated water vapor is naturally discharged.

[0034] The energized screen has an aperture of 500nm. The solid powder is crushed and dried on the energized screen. It can fall from the energized screen only after the particle size meets the requirements. The falling speed is determined by the flow rate of inert gas. This not only completes the particle size screening, but also allows the product to fully react. The powder that does not meet the requirements continues to react until it falls after meeting the requirements.

[0035] The method of the present invention prepares ultrafine anhydrous iron phosphate powder by combining precipitation method with high-temperature electric explosion, which can shorten the calcination time required for more than 8 hours to 10-20 seconds, and combines sintering and crushing processes to obtain iron phosphate with extremely low moisture content and extremely small particle size in one step, and the reaction is sufficient, and one screening can be completed during the reaction, which greatly reduces the total time and total energy consumption required for the entire process; the preparation process and device are simple, which reduces the industrial production cost of FePO4, a precursor of the positive electrode material, so that it can be more widely used; in addition, the FePO4 synthesized by the present invention is an ultrafine anhydrous iron phosphate powder with a moisture content of less than 0.5% and a particle size of less than 500nm, and its particle size is much smaller than that of conventional ultrafine anhydrous iron phosphate powder, and has very good processing performance, which provides a new method for the preparation of a precursor of the positive electrode material of a lithium iron phosphate battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a process flow chart for efficiently preparing ultrafine powder anhydrous ferric phosphate.

[0037] Figure 2 It is an equipment used in the method for efficiently preparing ultrafine powder anhydrous ferric phosphate.

[0038] Markings in the figure are: 1-raw material storage tank, 2-feeding port, 3-dispersion blade, 4-powered screen, 5-heat-conducting explosion-proof cavity wall, 6-high-temperature insulation outer cylinder, 7-constant temperature insulation layer, 8-heating ring, 9-discharge port, 10-air filter valve, 11-blower, 12-classifier, 13-screen, 14-product storage tank, 15-heating area, 16-sinking area, 17-inert gas inlet. DETAILED DESCRIPTION

[0039] The embodiments of the present application will be described in more detail below. The application can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein, but rather these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0040] The equipment used in the method for efficiently preparing ultrafine anhydrous ferric phosphate powder of the present invention comprises a rapid thermal shock device and a post-processing device: wherein the rapid thermal shock device comprises, from top to bottom, a raw material storage tank 1, a discharge port 2, a heating zone 15, a settling zone 16, and a discharge port 9; wherein the post-processing device is connected to a blower 11, a classifier 12, a screen 13 and a product storage tank 14 in sequence at the discharge port 9 of the rapid thermal shock device.

[0041] The outer shells of the heating area 15 and the sinking area 16 are high-temperature heat-insulating outer cylinders 6 , and a heat-conducting explosion-proof cavity wall 5 is arranged inside the high-temperature heat-insulating outer cylinders 6 .

[0042] The heating zone 15 is provided with a dispersion blade 3, an inert gas inlet 17 and an electrified screen 4, wherein the dispersion blade 3 and the inert gas inlet 17 are connected to the discharge port 2, and the electrified screen 4 is laid in a layer at a position 1 / 3 from the top of the heating zone, and the height is 1 / 8 of the total height of the heating zone.

[0043] A heating coil 8 and a constant temperature insulation layer 7 are arranged between the heat-conducting explosion-proof cavity wall 5 and the high-temperature insulation outer tube 6 of the sinking area 16, wherein the heating coil 8 is arranged close to the side of the high-temperature insulation outer tube 6, and the constant temperature insulation layer 7 is arranged close to the side of the heat-conducting explosion-proof cavity wall 5.

[0044] The settling area 16 is also provided with an air filter valve 10 , wherein the air filter valve 10 is connected with the settling area 16 and the external environment through the heat-conducting explosion-proof cavity wall 5 , the constant temperature insulation layer 7 , the heating coil 8 and the high-temperature insulation outer cylinder 6 in sequence.

[0045] The embodiment of the present invention is implemented with the following technical solution, and the specific steps include:

[0046] (1) Add the iron block to a 25% by mass phosphoric acid solution and heat to 90°C to perform a melting reaction. After 8 hours of reaction, measure the Fe(H2PO4)2 content in the solution. When the Fe(H2PO4)2 content in the solution is 18%, filter the reaction solution to obtain a Fe(H2PO4)2 solution in which the molar ratio of the iron block to the phosphoric acid is 0.975:1.

[0047] (2) The Fe(H2PO4)2 solution was heated to 35°C, stirring was started, hydrogen peroxide was added, and the reaction lasted for 60 minutes. Then, stirring was continued, and a 30% by mass fraction polyethylene glycol solution was added until the reaction was complete to obtain an oxidized solution, wherein the molar ratio of hydrogen peroxide to iron block was 0.5:1, and the molar ratio of polyethylene glycol solution to iron block was 0.08:1;

[0048] (3) adding distilled water to the oxidized solution, stirring for 10 minutes, heating to 90°C, and keeping the temperature for 50 minutes to obtain a ferric phosphate crystal solution;

[0049] (4) The hydrolyzed iron phosphate crystal liquid is filtered and separated, and the filtered solid phase is washed by centrifugation. The washed liquid is collected and its pH value is measured until the pH value of the washed liquid reaches 6.0, and the centrifugal washing is terminated. The solid iron phosphate after centrifugation is flash dried at a temperature of 180°C for 2 hours to obtain FePO4•2H2O;

[0050] (5) The prepared FePO4•2H2O is placed in a rapid thermal shock device and a post-treatment device for high-temperature electric explosion and post-treatment. First, the FePO4•2H2O is placed in a raw material storage tank 1, the dispersion blade 3 is turned on, nitrogen is introduced from the inert gas inlet 17, and the current of the electrified screen 4 is set to 10A, the voltage is 20kV, and the electrification duration is 20s; then the feed port 2 is opened to pass the FePO4•2H2O into the heating zone 15, and the power switch is turned on at the same time to allow the FePO4•2H2O to be subjected to high-temperature electric explosion and post-treatment. After the high-temperature electric explosion reaction, the FePO4 with qualified particle size falls through the electrified screen 4 and accumulates at the bottom of the sedimentation area 16. At the same time, the temperature of the sedimentation area is maintained at 90°C by the heating ring 8 and the constant temperature insulation layer 7. The air filter valve 10 equipped in the sedimentation area 16 ensures the partial pressure inside and outside the container, and the generated water vapor is naturally discharged. The reacted FePO4 is transmitted to the product storage tank 14 through the pipeline in sequence through the blower 11, the classifier 12, and the screen 13, and finally anhydrous iron phosphate with a particle size of less than 500nm is obtained.

[0051] The water content of FePO4 in the embodiment is 0.33% and the particle size is 450nm.

[0052] It can be seen that the method of the present invention can not only obtain FePO4 with extremely low moisture content and extremely small particle size, but also the high-temperature electric explosion process only takes 20 seconds to complete, and anhydrous iron phosphate with smaller particle size than conventional ultrafine anhydrous iron phosphate is obtained, which takes less time and energy; in addition, when the preparation conditions are: when the mass fraction of Fe(H2PO4)2 in the solution is 18-20%, distilled water is added to the oxidized solution and stirred for 5-10 minutes, heated to 70-90°C and kept warm for 50-70 minutes to obtain iron phosphate crystal liquid, the pH value of the hydrolyzed iron phosphate crystal liquid after washing is 5.9-6 .1, and the solid ferric phosphate after centrifugation is flash dried at 180-200°C for 1-2h to obtain FePO4·2H2O. Finally, under an inert atmosphere, the obtained FePO4·2H2O is passed into a rapid thermal shock device for high-temperature electric explosion, with a current of 10-20A, a voltage of 20kV, and a power-on duration of 10-20s. Within the above conditions, ultrafine powder anhydrous ferric phosphate with a water content of less than 0.5% and a particle size of less than 500nm can be obtained, which greatly reduces the total time and total energy consumption required for the entire process, saves production costs, and has good application prospects.

[0053] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. For example, any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this application, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for efficiently preparing ultrafine anhydrous ferric phosphate powder, comprising the steps of dissolving iron, oxidizing, crystallizing, drying and calcining, characterized in that: (1) Add the iron block to a 25% by mass phosphoric acid solution and heat to 90°C to perform a molten iron reaction. After 8 hours of reaction, measure the Fe(H2PO4)2 content in the solution. When the mass fraction of Fe(H2PO4)2 in the solution is 18-20%, filter the reaction solution to obtain a Fe(H2PO4)2 solution. (2) Heat the Fe(H2PO4)2 solution to 35°C, start stirring, add hydrogen peroxide, react for 60 minutes, continue stirring, add dispersant, and continue until the reaction is complete to obtain an oxidized solution; (3) adding distilled water to the oxidized solution, stirring for 5 to 10 minutes, heating to 70 to 90°C, and keeping the temperature for 50 to 70 minutes to obtain a ferric phosphate crystal solution; (4) The hydrolyzed iron phosphate crystal liquid is subjected to filter pressing to separate, the filtered solid phase is centrifuged and washed, the washed liquid is collected and its pH value is measured, and the centrifugal washing is terminated when the pH value of the washed liquid is 5.9-6.1, and the solid iron phosphate after centrifugation is flash dried to obtain FePO4·2H2O; (5) Under an inert atmosphere, the prepared FePO4·2H2O is introduced into a rapid thermal shock device for high-temperature electric explosion, with a current of 10-20A, a voltage of 20kV, and a duration of 10-20s to obtain ultrafine anhydrous iron phosphate; wherein in the rapid thermal shock device, the prepared FePO4·2H2O is fed into the top feed port of the raw material storage tank, and the solid material is dispersed at the top of the heating zone by a dispersing blade, and falls in the form of dust, and is dehydrated and crushed under the high temperature and high pressure conditions of the electrified screen, i.e., high-temperature electric explosion, and then, under the blowing of the inert gas, particles with qualified particle sizes fall freely from the electrified screen and accumulate at the bottom of the rapid thermal shock device to obtain ultrafine anhydrous iron phosphate.

2. The method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The molar ratio of iron block to phosphoric acid is 0.975:

1.

3. The method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The molar ratio of hydrogen peroxide to iron block is 0.5:

1.

4. The method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The molar ratio of the dispersant to the iron block is 0.08:1, wherein the dispersant is a polyethylene glycol solution with a mass fraction of 30-55%.

5. The method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The temperature of flash drying is 180~200℃ and the time is 1~2h.

6. The method for efficiently preparing ultrafine anhydrous ferric phosphate according to claim 1, characterized in that: The obtained ultrafine powder anhydrous ferric phosphate has a water content of less than 0.5% and a particle size of less than 500nm.

7. The method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The inert gas used in high temperature electric explosion is argon or nitrogen.

8. The method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The instantaneous temperature of high voltage electric explosion reaches 1800℃.

9. The equipment used in the method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 1, characterized in that: The equipment comprises a rapid thermal shock device and a post-processing device: wherein the rapid thermal shock device comprises, from top to bottom, a raw material storage tank (1), a feed outlet (2), a heating zone (15), a sedimentation zone (16), and a discharge port (9); wherein the post-processing device is connected to the discharge port (9) of the rapid thermal shock device in sequence with a blower (11), a classifier (12), a screen (13), and a product storage tank (14); wherein the heating zone (15) is provided with a dispersion blade (3), an inert gas inlet (17), and an electrified screen (4), wherein the dispersion blade (3) and the inert gas inlet (17) are connected to the feed outlet (2).

10. The device used in the method for efficiently preparing ultrafine anhydrous ferric phosphate powder according to claim 9, characterized in that: The outer shells of the heating zone (15) and the sinking zone (16) are high-temperature heat-insulating outer cylinders (6), and a heat-conducting explosion-proof cavity wall (5) is arranged inside the high-temperature heat-insulating outer cylinder (6).

11. The device used in the method for efficiently preparing ultrafine anhydrous ferric phosphate according to claim 9, characterized in that: The energized screen (4) is laid flat in a layer at a position 1 / 3 from the top of the heating zone, and the height is 1 / 8 of the total height of the heating zone.

12. The device used in the method for efficiently preparing ultrafine anhydrous ferric phosphate according to claim 10, characterized in that: A heating coil (8) and a constant temperature insulation layer (7) are arranged between the heat-conducting explosion-proof cavity wall (5) and the high-temperature heat-insulating outer cylinder (6) of the sinking area (16), wherein the heating coil (8) is arranged on a side close to the high-temperature heat-insulating outer cylinder (6), and the constant temperature insulation layer (7) is arranged on a side close to the heat-conducting explosion-proof cavity wall (5).

13. The equipment used in the method for efficiently preparing ultrafine anhydrous ferric phosphate according to claim 12, characterized in that: The sedimentation area (16) is also provided with an air filter valve (10), wherein the air filter valve (10) is connected to the sedimentation area (16) and the external environment through the heat-conducting explosion-proof cavity wall (5), the constant temperature insulation layer (7), the heating coil (8) and the high-temperature insulation outer cylinder (6) in sequence.

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