A continuous crushing, mixing and screening production process for sodium ferric sulfate, a sodium battery cathode material

Abstract

The invention discloses a continuous crushing, mixing and screening production process for sodium ferric sulfate, a sodium battery positive electrode material, and relates to the technical field of sodium ion battery materials. The invention comprises the following steps: fluidizing raw materials with a compressed nitrogen gas flow, controlling the material flow rate and pressure to pass the materials into a mixing and separation device, separating materials that do not meet target particle size requirements through mixing and separation, conveying the materials to a fluidized bed air flow pulverizer, cooling the pulverized materials to room temperature, returning the feed stream, and re-supplying the materials into the mixing and separation device for cyclic operation; and collecting the materials that meet the target particle size requirements separated in the mixing and separation device as products. The mixing and separation device plays the dual role of material mixing and particle separation, and the fluidized bed air flow pulverizer plays the dual role of material crushing and mixing. The invention organically combines material crushing, mixing and screening to achieve cyclic continuous production, and the obtained powder material has uniform crushing, high morphological consistency and excellent performance.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery materials, and in particular to a continuous crushing, mixing and screening production process of sodium ferric sulfate, a sodium battery positive electrode material. Background Art

[0002] Compared with lithium-ion batteries, the main advantage of sodium-ion batteries is that sodium is abundant in the earth's crust (accounting for 2.75%), which is more than 400 times that of lithium (accounting for 0.0065%). It is evenly distributed around the world and is relatively simple to refine. In addition, sodium-ion batteries have a wider operating temperature range (from -40°C to 80°C) and are suitable for various extreme climatic conditions. Sodium-ion batteries also have excellent fast charging capabilities and can be fully charged in about 10 minutes under extreme conditions. Therefore, the development of efficient and low-cost sodium-ion battery technology and its key materials is of great significance.

[0003] Sodium ferric sulfate (Na2Fe(SO4)2) is a new type of sodium cathode material with good application prospects. Its raw materials do not contain expensive non-ferrous metals and are low in cost, making it very suitable for large-scale production. In the preparation process of sodium ferric sulfate, a key link is to crush and screen the sodium ferric sulfate particles after high-temperature calcination, and fully mix them with conductive carbon powder until the treated mixture reaches the mixing uniformity, particle size distribution and average particle size required by the product indicators. In this process, how to complete the crushing, mixing and screening of product particles efficiently and at low cost has become the core and technical focus of this process; the invention patent application with publication number CN115020681A, entitled "A Carbon-coated Sodium Ferric Sulfate Cathode Material and Its Preparation Method", and the invention patent application with publication number CN116936769A, entitled "A Sodium Ion Battery Cathode Material and Its Preparation Method", both disclose ball milling treatment methods. However, traditional ball milling or sand milling methods are prone to introduce impurities, and the equipment has high energy consumption, which cannot meet the needs of process improvement. Summary of the Invention

[0004] The object of the present invention is to provide a continuous crushing, mixing and screening production process for sodium ferric sulfate, a sodium battery positive electrode material, to solve the problems mentioned in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a continuous crushing, mixing and screening production process for sodium ferric sulfate, a sodium positive electrode material, comprising the following specific contents: after fluidizing the raw materials with a compressed nitrogen gas flow, controlling the material flow rate and pressure to pass them into a mixing and separation device, separating the materials that do not meet the target particle size requirements through mixing and separation and conveying them to a fluidized bed air flow mill, cooling the crushed materials to room temperature and returning them to the feed stream, and then supplying them to the mixing and separation device again for circulation, collecting the materials that meet the target particle size requirements separated in the mixing and separation device as products; wherein the mixing and separation device plays the dual role of material mixing and particle separation, and the fluidized bed air flow mill plays the dual role of material crushing and mixing.

[0006] Preferably, the raw material is sodium ferric sulfate, or sodium ferric sulfate and conductive carbon powder, and the carbon content in the product is 0-5wt%.

[0007] In the preferred embodiment above, the conductive carbon powder is preferably SuperP conductive carbon black or graphene.

[0008] Preferably, the material flow rate range controlled when entering the mixing and separation equipment is 0.1-1.0m 3 / s, pressure is 1-10kPa.

[0009] Preferably, the crushing power of the fluidized bed air flow mill is 10-80kW. During the air flow crushing process, the powder particles are subjected to violent collision, friction and shearing, causing the material flow to heat up to 60-90°C.

[0010] Preferably, the crushed material is cooled to room temperature using an indirect contact heat exchanger.

[0011] Preferably, the particle size of the product is controllable between 5-25 μm, and the average particle size deviation is ≤±5.0 μm.

[0012] Preferably, the raw material is preliminarily crushed to a D50 of 10-100 μm before fluidization.

[0013] Preferably, the system used in the above process includes a feeding device, a mixing and separation device, a fluidized bed air flow mill, a product collection point and a heat exchange cooler. The discharge end of the feeding device is connected to the feed end of the mixing and separation device. The mixing and separation device is provided with two discharge ends. The discharge end with particles that meet the standards is connected to the product collection point, and the discharge end with particles that do not meet the standards is connected to the feed end of the fluidized bed air flow mill. The discharge end of the fluidized bed air flow mill is connected to the feed end of the heat exchange cooler, and the discharge end of the heat exchange cooler is connected to the feed end of the feeding device.

[0014] Preferably, the feeding device includes a flow control valve and a pressure buffer tank; the mixing and separation equipment adopts a cyclone separator; and a bag is provided at the product collection point to collect the powder and pack it.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The continuous crushing, mixing and screening production process of sodium ferric sulfate, a positive electrode material of sodium battery, combines a mixing separation device with a fluidized bed airflow mill, not only utilizing the separation and crushing functions of the two, but also completing the mixing of the returned recycled material and new material after crushing and the mixing of sodium ferric sulfate and conductive carbon powder in the separation device, and further mixing of sodium ferric sulfate and conductive carbon powder in the crushing device. Both devices are used with high efficiency, organically combining the crushing, mixing and screening of materials to realize cyclic continuous production, and benefiting from the combination of multiple unit operations, this production process optimizes the process flow on the original basis, which is conducive to improving energy efficiency and shortening the processing time. Compared with the past intermittent multi-stage operation, it is easier to achieve automated production.

[0017] 2. Compared with the conventional sand milling and ball milling schemes, the continuous crushing, mixing and screening production process of sodium ferric sulfate, a sodium battery positive electrode material, adopts fluidized bed airflow crushing, which reduces the introduction of impurities, has lower energy consumption, and the equipment has no moving parts and better reliability. The equipment required by the present invention has a simple structure and is easy to maintain, with strong practicality and outstanding cost reduction and efficiency improvement effects.

[0018] 3. The continuous crushing, mixing and screening production process of the sodium ferric sulfate positive electrode material can produce a powder material with uniform crushing, high morphology consistency and excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow diagram of the present invention.

[0020] Figure 2 3 is a scanning electron microscope (SEM) image of the sodium ferric sulfate raw material powder before treatment in Example 3 of the present invention.

[0021] Figure 3 This is a scanning electron microscope (SEM) image of the sodium ferric sulfate product powder after the crushing, mixing, and screening processes in Example 3 of the present invention.

[0022] Figure 4 This is a scanning electron microscope (SEM) image of a sodium ferric sulfate / graphene-5 wt% carbon-coated composite product obtained by coating graphene on the surface of sodium ferric sulfate particles using this process system in Example 4 of the present invention.

[0023] Figure 5 This is the sodium electrical performance of the sodium ferric sulfate / graphene-5wt% carbon-coated composite positive electrode material obtained by coating graphene on the surface of sodium ferric sulfate particles through this process system in Example 4 of the present invention.

[0024] Figure 1 In: 1. Feeding device; 2. Mixing and separation equipment; 3. Fluidized bed airflow mill; 4. Product collection area; 5. Heat exchange cooler. DETAILED DESCRIPTION

[0025] A continuous crushing, mixing and screening production process for sodium ferric sulfate, a sodium battery positive electrode material, includes the following specific contents: after fluidizing the raw materials with a compressed nitrogen gas flow, the material flow rate and pressure are controlled to pass into a mixing and separation device, the materials that do not meet the target particle size requirements are separated through mixing and separation and conveyed to a fluidized bed air flow mill, the crushed materials are cooled to room temperature and returned to the feed stream, and are again fed into the mixing and separation device for circulation, and the materials that meet the target particle size requirements separated in the mixing and separation device are collected as products; the mixing and separation device plays the dual role of material mixing and particle separation, and the fluidized bed air flow mill plays the dual role of material crushing and mixing.

[0026] The above is the core idea of ​​the present invention, wherein the raw material can be sodium ferric sulfate. If the product performance is to be improved, sodium ferric sulfate and conductive carbon powder can be used. The carbon content in the product is 0-5wt%, and the conductive carbon powder is preferably SuperP conductive carbon black or graphene. When sodium ferric sulfate and conductive carbon powder are mixed, the mixing process in the mixing and separation equipment and the mixing process in the fluidized bed airflow mill can both simultaneously perform the carbon coating effect.

[0027] In a preferred embodiment, see Figure 1 The system used in the above process includes a feeding device 1, a mixing and separation device 2, a fluidized bed airflow mill 3, a product collection point 4 and a heat exchange cooler 5. The discharge end of the feeding device 1 is connected to the feed end of the mixing and separation device 2. The mixing and separation device 2 is provided with two discharge ends. The discharge end with particles that meet the standards is connected to the product collection point 4, and the discharge end with particles that do not meet the standards is connected to the feed end of the fluidized bed airflow mill 3. The discharge end of the fluidized bed airflow mill 3 is connected to the feed end of the heat exchange cooler 5, and the discharge end of the heat exchange cooler 5 is connected to the feed end of the feeding device 1.

[0028] The above-mentioned feeding device 1 may include a flow control valve and a pressure buffer tank for adjusting the pressure and flow of the material; the mixing and separation equipment 2 should preferably adopt a cyclone separator, specifically a chemical standard equipment with a cylindrical part diameter of 20-150 cm; in addition, since the product is a powder, the product collection point 4 can be provided with a bag to collect the powder and pack it.

[0029] When entering the mixing and separation equipment, the material flow rate can be further controlled to a range of 0.1-1.0m 3 / s, pressure is 1-10kPa.

[0030] In addition, the crushing power of the fluidized bed air flow mill should be selected to be 10-80kW. During the air flow crushing process, the powder particles will have violent collisions, friction, and shearing effects, causing the material flow to heat up to 60-90℃, which can strengthen the bonding degree between sodium ferric sulfate and conductive carbon black and effectively improve the uniformity of the mixing of the two materials. Since the material heats up during the crushing process, the crushed material generally needs to be cooled to room temperature. An indirect contact heat exchanger can be used for cooling, such as Figure 1 The elbow shown in FIG passes through a container containing a circulating cooling medium.

[0031] The particle size of the product obtained by the process of the present invention is controllable between 5-25 μm, and the average deviation of the particle size is ≤±5.0 μm, that is, the maximum and minimum values ​​of the size are within the range of D50±5, and the uniformity is good.

[0032] Based on the equipment principle and energy consumption of the fluidized bed jet mill, it is best to perform preliminary crushing treatment on the raw materials to a D50 of 10-100μm before fluidization. If the material initially meets the requirements, no treatment is required.

[0033] The technical solutions in the present invention will be further described below in conjunction with the embodiments. Obviously, the embodiments described are only a very small part of the embodiments formed during the exploration process of the present invention, and cannot be all the embodiments.

[0034] Example 1:

[0035] The sodium ferric sulfate raw material was post-processed using the continuous crushing, mixing, and screening process described in this patent. The feed stream contained sodium ferric sulfate particles at a concentration of 0.5 g / L and was maintained at room temperature (20°C). The initial particle size distribution of the material particles was D10 = 7 μm, D50 = 38 μm, and D90 = 105 μm. In this embodiment, no carbon powder was added for compounding (the carbon content of the output product was 0 wt%). After crushing and screening, the product particle size distribution was required to be D10 = 2 μm, D50 = 8 μm, and D90 = 12 μm.

[0036] See Figure 1 The sodium ferric sulfate fluid material first passes through the feeding device, and after being adjusted by the valve and buffer tank, the flow rate is adjusted to 0.4m 3 / s, the gas pressure is adjusted to 8kPa. Then the flow enters the cyclone separator, the cylinder diameter is 40cm, the inlet gas velocity is 20m / s, and the gas density is 1.2kg / m 3 , the gas viscosity is 1.8*10 -5 Pa*s, solid density of sodium ferric sulfate is 1100 kg / m 3 , the minimum sieveable particle size d of this centrifugal separation device can be calculated c=4.5um (<cutting particle size D50=8um), which meets the product requirements. The air flow pressure drop of the coarse particles falling from the cyclone separation device is about 1.9kPa. After being pressurized, they enter the fluidized bed air flow crushing device, and the crushing peak power is 45kW. After the violent collision, friction and shearing of the powder particles during the air flow crushing process, the coarse sodium ferric sulfate material is further broken and refined, the particle size is significantly reduced, and the material flow is significantly heated up (about 80°C after discharge). After the hot stream of the material is cooled to room temperature (about 25°C) through the heat exchange cooler, it is re-introduced into the feeding device, mixed with the feed stream, and then re-entered the cyclone separation device for screening. This operation is continued until all the materials reach the particle size distribution required by the product, and high-quality pure sodium ferric sulfate product powder is collected.

[0037] Example 2:

[0038] The continuous crushing, mixing and screening process in this patent is adopted. In this embodiment, the sodium ferric sulfate raw material is post-processed and carbon-coated. The conductive carbon black raw material used is SuperP (specific surface area 62m 2 / g, D50 = 2 μm), and is fed together with sodium ferric sulfate. The feed stream contains 0.25 g / L of sodium ferric sulfate particles and 1.26 mg / L of conductive carbon black particles. The composite has a carbon content of 0.5 wt% and is maintained at room temperature (20°C). The initial particle size distribution of the material particles is D10 = 12 μm, D50 = 38 μm, and D90 = 105 μm. After crushing and screening, the product particle size distribution is required to be D10 = 12 μm, D50 = 16 μm, and D90 = 18 μm.

[0039] See Figure 1 The sodium ferric sulfate fluid material first passes through the feeding device and is adjusted through the valve and buffer tank to adjust the flow rate to 1.0m 3 / s, the gas pressure is adjusted to 7kPa. Then the flow enters the cyclone separator, the cylinder diameter is 120cm, the inlet gas velocity is 5.6m / s, and the gas density is 1.2kg / m 3 , the gas viscosity is 1.8*10 -5 Pa*s, solid density of sodium ferric sulfate is 1100 kg / m 3 , the minimum sieveable particle size d of this centrifugal separation device can be calculated c=14.9um (<cutting particle size D50=16um), which meets the product requirements. The pressure drop of the coarse particles falling from the cyclone separation device is about 0.15kPa. After being pressurized, they enter the fluidized bed air flow crushing device with a crushing peak power of 80kW. After the intense collision, friction and shearing of the powder particles during the air flow crushing process, the coarse sodium ferric sulfate material is further crushed and refined, the particle size is significantly reduced, and the material flow is significantly heated up (about 70°C after discharge), and is closely combined with the SuperP conductive carbon powder. After the hot flow of the composite material is cooled to room temperature (about 25°C) by the heat exchange cooler, it is re-introduced into the feeding device, mixed with the feed flow, and then re-entered the cyclone separation device for screening. This operation is continued until all the materials reach the particle size distribution required by the product, and high-quality sodium ferric sulfate / SuperP-0.5wt% carbon-coated product powder is collected.

[0040] Example 3:

[0041] The continuous crushing, mixing and screening process in this patent is used to post-process the sodium ferric sulfate positive electrode. The feed stream contains sodium ferric sulfate particles at a concentration of 1.2g / L and the temperature is room temperature (20°C). In this embodiment, no carbon powder is added for compounding (the carbon content of the output product is 0wt%). The initial particle size distribution of the material particles is D10 = 2um, D50 = 14um, D90 = 57um. The particle size distribution of the material is as follows: Figure 2 As shown in the SEM image, it can be seen that the particles of sodium ferric sulfate before treatment are large and the particle size distribution is very uneven. It is required that after crushing and screening, the particle size distribution of the product material particles falls within D10 = 2μm, D50 = 6μm, and D90 = 10μm.

[0042] During the entire continuous crushing and screening process, the sodium ferric sulfate fluid material first passes through the feeding device and is adjusted by the valve and buffer tank inside the controller to adjust the flow rate to 0.1m 3 / s, the gas pressure is adjusted to 3.2kPa. Then the flow enters the cyclone separator, the cylinder diameter is 20cm, the inlet gas velocity is 20m / s, and the gas density is 1.2kg / m 3 , the gas viscosity is 1.8*10 -5 Pa*s, solid density of sodium ferric sulfate is 1100 kg / m 3 , the minimum sieveable particle size d of this centrifugal separation device can be calculated c=3.2um (<cutting particle size D50=6um), which meets the product requirements. The air flow pressure drop of the coarse particles falling from the cyclone separation device is about 1.9kPa. After being pressurized, they enter the fluidized bed air flow crushing device, and the crushing peak power is 10kW. After the violent collision, friction and shearing of the powder particles in the air flow crushing process, the coarse sodium ferric sulfate material is further broken and refined, the particle size is significantly reduced, and the material flow is significantly heated up (about 60°C after discharge). After the hot stream of the material is cooled to room temperature (about 25°C) through the heat exchange cooler, it is re-introduced into the feeding device, mixed with the feed stream, and then re-entered into the cyclone separation device for screening. This operation is continued until all the materials reach the particle size distribution required by the product, and high-quality pure sodium ferric sulfate product powder is collected.

[0043] The particle micromorphology of sodium iron sulfate powder after continuous crushing and screening is as follows: Figure 3 As shown in the SEM image in , it can be seen that the particle size of sodium iron sulfate after treatment is significantly reduced, and the uniformity of particle size distribution is effectively improved.

[0044] Example 4:

[0045] The continuous crushing, mixing and screening process in this patent is adopted. In this embodiment, the sodium ferric sulfate raw material is post-processed and carbon-coated. The conductive carbon black raw material used is the company's own high-quality graphene (specific surface area 45m 2 / g, D50 = 0.8μm), and is co-fed with sodium ferric sulfate. The feed stream contains 1.2g / L of sodium ferric sulfate particles and 0.063g / L of graphene. The composite has a carbon content of 5wt% and is maintained at room temperature (20°C). The initial particle size distribution of the material particles is D10 = 2μm, D50 = 14μm, and D90 = 57μm. After processing, the product particle size distribution is required to be D10 = 2μm, D50 = 6μm, and D90 = 10μm.

[0046] During the entire continuous crushing, mixing and screening process, the sodium ferric sulfate fluid material first passes through the feeding device and is adjusted by the valve and buffer tank inside the controller to adjust the flow rate to 0.1m 3 / s, the gas pressure is adjusted to 3.2kPa. Then the flow enters the cyclone separator, the cylinder diameter is 20cm, the inlet gas velocity is 20m / s. The gas density is 1.2kg / m 3 , the gas viscosity is 1.8*10 -5 Pa*s, solid density of sodium ferric sulfate is 1100 kg / m 3 , the minimum sieveable particle size d of this centrifugal separation device can be calculated c=3.2um (<cutting particle size D50=6um), which meets the product requirements. The air flow pressure drop of the coarse particles falling from the cyclone separation device is about 1.9kPa. After being pressurized, it enters the fluidized bed air flow crushing device, and the crushing peak power is 10kW. After the violent collision, friction and shearing of the powder particles in the air flow crushing process, the sodium ferric sulfate coarse material is further crushed and refined, the particle size is significantly reduced, and the material flow is significantly heated up (about 60°C after discharge), and is closely combined with the graphene conductive agent. After the hot stream of the material is cooled to room temperature (about 25°C) through the heat exchange cooler, it is re-introduced into the feeding device, mixed with the feed stream, and then re-entered into the cyclone separation device for screening. This operation is continued until all the materials reach the particle size distribution required by the product, and high-quality sodium ferric sulfate / graphene-5wt% carbon-coated product powder is collected. The particle micromorphology of the sodium ferric sulfate / graphene composite powder after continuous crushing and screening is as follows Figure 4 As shown in the SEM image, it can be seen that the particle size of the sodium iron sulfate after treatment is significantly reduced, and the uniformity of the particle size distribution is effectively improved. By using the product powder as the positive electrode material for sodium battery assembly, Figure 5 As shown in the figure, after testing, at a discharge current of 0.1C, the battery capacity can reach 83.4mAh g -1 , showing excellent product performance.

[0047] Comparative Example 1:

[0048] The same sodium ferric sulfate and conductive carbon black raw materials as in Example 2 were used, mixed evenly at a ratio of 0.5 wt% carbon content in the composite, and ground using a horizontal ball mill to a D50 of 16 μm to obtain a sodium ferric sulfate / SuperP-0.5 wt% carbon-coated product powder, which was used as a sodium battery positive electrode material for battery assembly testing under the same assembly conditions as in Example 2.

[0049] Table 1 Performance test of products in Examples and Comparative Examples and assembled batteries

[0050]

[0051] The test data in Table 1 show that the rate performance of the battery obtained by carbon coating with this process is significantly improved (Example 2 and Example 4), and compared with the comparative example using ball milling, all battery products obtained by this process have excellent specific capacity (>80 mAh g -1 , 0.1C), comparing Example 2 with the comparative example, it is obvious that the product prepared by the method of the present invention has better performance. These results fully reflect the advantages and effectiveness of the method proposed in the present invention.

[0052] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

[0053] Any matters not described in detail in the present invention are well-known technologies to those skilled in the art.

Claims

1. A continuous crushing, mixing and screening production process for sodium ferric sulfate, a sodium cathode material, characterized in that: The method includes the following specific contents: after fluidizing the raw materials with compressed nitrogen gas, the material flow rate and pressure are controlled to be passed into a mixing and separation device; the material that does not meet the target particle size requirements is separated by the mixing and separation device and conveyed to a fluidized bed air flow mill; the crushed material is cooled to room temperature and then returned to the feed stream, and then fed back into the mixing and separation device for a cycle; the material that meets the target particle size requirements separated by the mixing and separation device is collected as the product; the mixing and separation device performs the dual functions of material mixing and particle separation, and the fluidized bed air flow mill performs the dual functions of material crushing and mixing; The raw materials are sodium ferric sulfate and conductive carbon powder, the carbon content in the product is 0-5wt%, and the conductive carbon powder uses SuperP conductive carbon black or graphene; The system adopted in the process includes a feeding device (1), a mixing and separating device (2), a fluidized bed air flow mill (3), a product collection point (4) and a heat exchange cooler (5), wherein the discharge end of the feeding device (1) is connected to the feed end of the mixing and separating device (2), the mixing and separating device (2) is provided with two discharge ends, the discharge end for particles meeting the standards is connected to the product collection point (4), and the discharge end for particles not meeting the standards is connected to the feed end of the fluidized bed air flow mill (3), the discharge end of the fluidized bed air flow mill (3) is connected to the feed end of the heat exchange cooler (5), and the discharge end of the heat exchange cooler (5) is connected to the feed end of the feeding device (1); the feeding device (1) includes a flow control valve and a pressure buffer tank; the mixing and separating device (2) adopts a cyclone separator; and the product collection point (4) is provided with a bag for collecting powder for packaging.

2. The continuous crushing, mixing and screening production process of sodium ferric sulfate, a sodium cathode material, according to claim 1, is characterized in that: The material flow rate range controlled when entering the mixing and separation equipment is 0.1-1.0m 3 / s, pressure is 1-10kPa.

3. The continuous crushing, mixing and screening production process of sodium ferric sulfate, a sodium cathode material, according to claim 1, is characterized in that: The crushing power of the fluidized bed air flow mill is 10-80kW. During the air flow crushing process, the powder particles are subjected to violent collision, friction and shearing, causing the material flow to heat up to 60-90°C.

4. The continuous crushing, mixing and screening production process of sodium ferric sulfate, a sodium cathode material, according to claim 1, is characterized in that: The crushed material is cooled to room temperature using an indirect contact heat exchanger.

5. The continuous crushing, mixing and screening production process of sodium ferric sulfate as a sodium cathode material according to claim 1, characterized in that: The particle size of the product is controllable between 5-25 μm, and the average deviation of the particle size is ≤±5.0 μm.

6. The continuous crushing, mixing and screening production process of sodium ferric sulfate as a sodium cathode material according to claim 5, characterized in that: The raw materials are preliminarily crushed to a D50 of 10-100 μm before fluidization.

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